Is anyone doing EDM chambers? I have been reading a bit about this and it seems like the best way to do it. Are any of the shops set up for this? I haven't heard of anyone doing it on this site. Any opinions?
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Gunsmithing EDM chambering
- Thread starter Shortdraw
- Start date
Re: EDM chambering
Filthy expensive for any appreciable gain in accuracy over a competent smith with a reamer...
Josh
Filthy expensive for any appreciable gain in accuracy over a competent smith with a reamer...
Josh
Re: EDM chambering
i don't see there being much, if any potential for accuracy improvement over the current method.
i don't work with edm but i wonder how common a sinker edm is that can handle a barrel length part plus the electrode?
i don't see there being much, if any potential for accuracy improvement over the current method.
i don't work with edm but i wonder how common a sinker edm is that can handle a barrel length part plus the electrode?
Re: EDM chambering
Their was a complany doing TC Encore barrel with EDM chambering a while back , never heard any complaints about accuracy.
Like Glen said its a solution to a problem that dosen't exist
Their was a complany doing TC Encore barrel with EDM chambering a while back , never heard any complaints about accuracy.
Like Glen said its a solution to a problem that dosen't exist
Re: EDM chambering
EDM chambering would also take WAY more time for almost no gain in accuracy. Also the surface finish that it leaves wouldn't be very good for case extraction unless you polished it afterwards.
EDM chambering would also take WAY more time for almost no gain in accuracy. Also the surface finish that it leaves wouldn't be very good for case extraction unless you polished it afterwards.
Re: EDM chambering
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: JJones75</div><div class="ubbcode-body">Their was a complany doing TC Encore barrel with EDM chambering a while back , never heard any complaints about accuracy.
Like Glen said its a solution to a problem that dosen't exist </div></div>
The company is OTT, located in Dover, New Hampshire.
OTT EDM chambering
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: JJones75</div><div class="ubbcode-body">Their was a complany doing TC Encore barrel with EDM chambering a while back , never heard any complaints about accuracy.
Like Glen said its a solution to a problem that dosen't exist </div></div>
The company is OTT, located in Dover, New Hampshire.
OTT EDM chambering
Re: EDM chambering
Not sold on it yet. where I could see an application for it is chamber lined barrels
Not sold on it yet. where I could see an application for it is chamber lined barrels
Re: EDM chambering
Stellite chamber liners? From what I understand, Sabre Defense lines the chambers of their 50s with this stuff, though I doubt that they would be sinking these chambers.
Stellite chamber liners? From what I understand, Sabre Defense lines the chambers of their 50s with this stuff, though I doubt that they would be sinking these chambers.
Re: EDM chambering
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: tnwill</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: JJones75</div><div class="ubbcode-body">Their was a complany doing TC Encore barrel with EDM chambering a while back , never heard any complaints about accuracy.
Like Glen said its a solution to a problem that dosen't exist </div></div>
The company is OTT, located in Dover, New Hampshire.
OTT EDM chambering
</div></div> Yes, that is the place. The barrels are very expensive, and they have like a year and a half wait on them. Supposed to be top grade. Seems like a good way to do it, although not neccesary. Cost prohibitive I guess.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: tnwill</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: JJones75</div><div class="ubbcode-body">Their was a complany doing TC Encore barrel with EDM chambering a while back , never heard any complaints about accuracy.
Like Glen said its a solution to a problem that dosen't exist </div></div>
The company is OTT, located in Dover, New Hampshire.
OTT EDM chambering
</div></div> Yes, that is the place. The barrels are very expensive, and they have like a year and a half wait on them. Supposed to be top grade. Seems like a good way to do it, although not neccesary. Cost prohibitive I guess.
Re: EDM chambering
About 5 or 6 years ago, a customer came to me to re-chamber a TC Encore barrel from 17 HMR to a wildcat based on a 357 Maximum case necked down to 17. I do not fool with TC barrels. He sent the barrel somewhere and had the chamber EDM'd. When he got it back he brought it back for me to borescope. We were both concerned about the "frosty" look of the chamber walls. After fireforming some brass we were both amazed at how the fired brass looked. You could not see any difference between this brass and other fired brass from other chambers. He has been shooting this Encore ever since with excellent results. I don't remember how much it cost but he has been happy.
About 5 or 6 years ago, a customer came to me to re-chamber a TC Encore barrel from 17 HMR to a wildcat based on a 357 Maximum case necked down to 17. I do not fool with TC barrels. He sent the barrel somewhere and had the chamber EDM'd. When he got it back he brought it back for me to borescope. We were both concerned about the "frosty" look of the chamber walls. After fireforming some brass we were both amazed at how the fired brass looked. You could not see any difference between this brass and other fired brass from other chambers. He has been shooting this Encore ever since with excellent results. I don't remember how much it cost but he has been happy.
Re: EDM chambering
i could very well be wrong, but don't the contenders have a lug welded to the od of the barrel in the chamber area? if that is true, due to the haz, there is the potential for differing hardness in the chamber area. that <span style="font-style: italic">could</span> cause a chamber reamer to push away from the centerline of the bore. i could see in this case having a theoretical reason to edm the chamber.
i could very well be wrong, but don't the contenders have a lug welded to the od of the barrel in the chamber area? if that is true, due to the haz, there is the potential for differing hardness in the chamber area. that <span style="font-style: italic">could</span> cause a chamber reamer to push away from the centerline of the bore. i could see in this case having a theoretical reason to edm the chamber.
Re: EDM chambering
That thought never entered my mind. Don't have a clue. I don't like rechambering them because there is no room for even the slightest error. If the reamer drags a chip or chatters, the barrel is lost.
That thought never entered my mind. Don't have a clue. I don't like rechambering them because there is no room for even the slightest error. If the reamer drags a chip or chatters, the barrel is lost.
Re: EDM chambering
Stellite liners have been around for quite awhile. A very old friend of mine named Bo Clerke helped develop the manufacturing process.
It's a material tolerant of all the nasties associative with chamber erosion. Commonly used on the bigger crew served machine guns and other wiz bang automatics used to kill people in quantity.
Carbide tooling is a beautiful thing used in the right application.
Stellite liners have been around for quite awhile. A very old friend of mine named Bo Clerke helped develop the manufacturing process.
It's a material tolerant of all the nasties associative with chamber erosion. Commonly used on the bigger crew served machine guns and other wiz bang automatics used to kill people in quantity.
Carbide tooling is a beautiful thing used in the right application.
Re: EDM chambering
Chad, I didn't know you knew Bo. What a great guy. 30 min. with him is like a semester of school. I stop to see him everytime I go to Raton.
Chad, I didn't know you knew Bo. What a great guy. 30 min. with him is like a semester of school. I stop to see him everytime I go to Raton.
Re: EDM chambering
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 300sniper</div><div class="ubbcode-body">i could very well be wrong, but don't the contenders have a lug welded to the od of the barrel in the chamber area? if that is true, due to the haz, there is the potential for differing hardness in the chamber area. that <span style="font-style: italic">could</span> cause a chamber reamer to push away from the centerline of the bore. i could see in this case having a theoretical reason to edm the chamber. </div></div>
Sounds like a good theory. Seems like T/C can't seem to chamber their own barrels very well themselves. Maybe they should invest in a EDM setup.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 300sniper</div><div class="ubbcode-body">i could very well be wrong, but don't the contenders have a lug welded to the od of the barrel in the chamber area? if that is true, due to the haz, there is the potential for differing hardness in the chamber area. that <span style="font-style: italic">could</span> cause a chamber reamer to push away from the centerline of the bore. i could see in this case having a theoretical reason to edm the chamber. </div></div>
Sounds like a good theory. Seems like T/C can't seem to chamber their own barrels very well themselves. Maybe they should invest in a EDM setup.
Re: EDM chambering
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 300sniper</div><div class="ubbcode-body">i could very well be wrong, but don't the contenders have a lug welded to the od of the barrel in the chamber area? if that is true, due to the haz, there is the potential for differing hardness in the chamber area. that <span style="font-style: italic">could</span> cause a chamber reamer to push away from the centerline of the bore. i could see in this case having a theoretical reason to edm the chamber. </div></div>
If the HAZ is big enough to extend into the chamber area, they are welding it wrong.....
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 300sniper</div><div class="ubbcode-body">i could very well be wrong, but don't the contenders have a lug welded to the od of the barrel in the chamber area? if that is true, due to the haz, there is the potential for differing hardness in the chamber area. that <span style="font-style: italic">could</span> cause a chamber reamer to push away from the centerline of the bore. i could see in this case having a theoretical reason to edm the chamber. </div></div>
If the HAZ is big enough to extend into the chamber area, they are welding it wrong.....
Re: EDM chambering
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: chpprguy</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 300sniper</div><div class="ubbcode-body">i could very well be wrong, but don't the contenders have a lug welded to the od of the barrel in the chamber area? if that is true, due to the haz, there is the potential for differing hardness in the chamber area. that <span style="font-style: italic">could</span> cause a chamber reamer to push away from the centerline of the bore. i could see in this case having a theoretical reason to edm the chamber. </div></div>
If the HAZ is big enough to extend into the chamber area, they are welding it wrong..... </div></div>
i have not even seen a contender in a few years and i really didn't pay much attention to the one i did see. i really don't know the barrel diameter at the chamber or what kind of weld process is used to attach the lug. i don't work with contenders or edm so it was just a theory of why some people are using edm to chamber contender barrels.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: chpprguy</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 300sniper</div><div class="ubbcode-body">i could very well be wrong, but don't the contenders have a lug welded to the od of the barrel in the chamber area? if that is true, due to the haz, there is the potential for differing hardness in the chamber area. that <span style="font-style: italic">could</span> cause a chamber reamer to push away from the centerline of the bore. i could see in this case having a theoretical reason to edm the chamber. </div></div>
If the HAZ is big enough to extend into the chamber area, they are welding it wrong..... </div></div>
i have not even seen a contender in a few years and i really didn't pay much attention to the one i did see. i really don't know the barrel diameter at the chamber or what kind of weld process is used to attach the lug. i don't work with contenders or edm so it was just a theory of why some people are using edm to chamber contender barrels.
Re: EDM chambering
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: chpprguy</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 300sniper</div><div class="ubbcode-body">i could very well be wrong, but don't the contenders have a lug welded to the od of the barrel in the chamber area? if that is true, due to the haz, there is the potential for differing hardness in the chamber area. that <span style="font-style: italic">could</span> cause a chamber reamer to push away from the centerline of the bore. i could see in this case having a theoretical reason to edm the chamber. </div></div>
If the HAZ is big enough to extend into the chamber area, they are welding it wrong..... </div></div>
...or they are not stress relieving them.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: chpprguy</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 300sniper</div><div class="ubbcode-body">i could very well be wrong, but don't the contenders have a lug welded to the od of the barrel in the chamber area? if that is true, due to the haz, there is the potential for differing hardness in the chamber area. that <span style="font-style: italic">could</span> cause a chamber reamer to push away from the centerline of the bore. i could see in this case having a theoretical reason to edm the chamber. </div></div>
If the HAZ is big enough to extend into the chamber area, they are welding it wrong..... </div></div>
...or they are not stress relieving them.
Re: EDM chambering
TC weld their lugs on and when done properly with preheating and long cool donw its not hard to keep from irregular hardness in the chamber area.
I've checked my Bullberry barrel and the chamber in it is cut as strait as can be.
I also have several factory TC barrel that are all pretty damn close
TC weld their lugs on and when done properly with preheating and long cool donw its not hard to keep from irregular hardness in the chamber area.
I've checked my Bullberry barrel and the chamber in it is cut as strait as can be.
I also have several factory TC barrel that are all pretty damn close
Re: EDM chambering
I think that cutting chambers with either EDMs or reamers both have inherent problems, the most notable one being the necessity to align either tool with the bore.
Try drilling a deep, high quality hole in a lathe and you will quickly understand how difficult it is to align a drill or a reamer with an existing hole, which presumably, is not, or should not be, running out. Since everyone is always after the perfectly concentric chamber, why isn't anyone using boring bars to cut the chamber?
If you present anyone highly skilled in manufacturing with a part having an existing bore and you ask them to cut another internal feature perfectly concentric with the bore, I guarantee that their first choice will not be an attempt to stuff some custom reamer down and existing hole. Within the firearms business, at least within the higher end or custom sector, this has become common practice largely because most gunsmiths that chamber barrels do not have the CNC lathe required to bore a chamber efficiently.
I would not be surprised to see a push towards bored chambers in the future. The advantages are significant, those being inherent concentricity and design flexibility. Nowadays, with indexable drills and carbide boring bars being common place, there is no reason not to bore chambers. A small investment in the process and some tooling by someone who already has a lathe is all that would be required to offer this service at a competitive price. Hmmm, maybe I ought to do it?
Is there anyone out there who currently bores chambers and is willing to share his experience with us?
I think that cutting chambers with either EDMs or reamers both have inherent problems, the most notable one being the necessity to align either tool with the bore.
Try drilling a deep, high quality hole in a lathe and you will quickly understand how difficult it is to align a drill or a reamer with an existing hole, which presumably, is not, or should not be, running out. Since everyone is always after the perfectly concentric chamber, why isn't anyone using boring bars to cut the chamber?
If you present anyone highly skilled in manufacturing with a part having an existing bore and you ask them to cut another internal feature perfectly concentric with the bore, I guarantee that their first choice will not be an attempt to stuff some custom reamer down and existing hole. Within the firearms business, at least within the higher end or custom sector, this has become common practice largely because most gunsmiths that chamber barrels do not have the CNC lathe required to bore a chamber efficiently.
I would not be surprised to see a push towards bored chambers in the future. The advantages are significant, those being inherent concentricity and design flexibility. Nowadays, with indexable drills and carbide boring bars being common place, there is no reason not to bore chambers. A small investment in the process and some tooling by someone who already has a lathe is all that would be required to offer this service at a competitive price. Hmmm, maybe I ought to do it?
Is there anyone out there who currently bores chambers and is willing to share his experience with us?
Re: EDM chambering
machine time for a EDM is usually a lot more expensive then a CNC Lathe........
machine time for a EDM is usually a lot more expensive then a CNC Lathe........
Re: EDM chambering
Many of the top accuracy riflesmiths are boring their chambers.
I bore to within .030" and then finish with the reamer.
Many of the top accuracy riflesmiths are boring their chambers.
I bore to within .030" and then finish with the reamer.
Re: EDM chambering
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: DocEd</div><div class="ubbcode-body">Many of the top accuracy riflesmiths are boring their chambers.
I bore to within .030" and then finish with the reamer. </div></div>
Correct me if I'm wrong, but I think that TK is saying cut the chamber entirely with carbide tooled boring operations, skip the reamer entirely.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: DocEd</div><div class="ubbcode-body">Many of the top accuracy riflesmiths are boring their chambers.
I bore to within .030" and then finish with the reamer. </div></div>
Correct me if I'm wrong, but I think that TK is saying cut the chamber entirely with carbide tooled boring operations, skip the reamer entirely.
Re: EDM chambering
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: TheodoreKaragias</div><div class="ubbcode-body">
-Why isn't anyone using boring bars to cut the chamber?
If you present anyone highly skilled in manufacturing with a part having an existing bore and you ask them to cut another internal feature perfectly concentric with the bore, I guarantee that their first choice will not be an attempt to stuff some custom reamer down and existing hole. Within the firearms business, at least within the higher end or custom sector, this has become common practice largely because most gunsmiths that chamber barrels do not have the CNC lathe required to bore a chamber efficiently.
I would not be surprised to see a push towards bored chambers in the future. The advantages are significant, those being inherent concentricity and design flexibility. Nowadays, with indexable drills and carbide boring bars being common place, there is no reason not to bore chambers. A small investment in the process and some tooling by someone who already has a lathe is all that would be required to offer this service at a competitive price. Hmmm, maybe I ought to do it?
Is there anyone out there who currently bores chambers and is willing to share his experience with us?
</div></div>
I own a Doosan Mecatec 280N production slant bed turning center that I use exclusively for barrel work.
I can promise anyone here the idea of single pointing a chamber with a boring bar in any modern centerfire rifle cartridge is a daunting task. I'd rather have invasive dentistry minus the anesthesia. Solid carbide is pretty hard/tough stuff. Imagine a 300 Rem Ultra and how long it is. That's how long your boring bar has to be. Now you have to make it small enough to fit up in the throat. That means it's swept arc cannot exceed .297" on a 30 cal bore. The challenges only exponentially increase as the bullets (bore) gets smaller. Now ask where are the chips going to go? Chip evacuation is EVERYTHING in deep hole machining. Without it your burning visa cards on barrels, more boring bars, and Vicoden from India mail order. Nevermind that to get that boring bar to cut anything that resembles a decent finish its going to require significant depth of cut. Now your chip evacuation problem just got really intense. If you try making "squealer" cuts (there's a reason for the name) your going to end up with a boring bar that acts more like a stylus on a record player than a cutting tool.
PROPERLY set up there is NOTHING wrong with using a form tool to cut chambers. (which is all a chamber reamer really is)
The trick is the set up. I can promise anyone here or in the world that I can cut a chamber to a TIR (total indicated Runout) of .00025" or better. The best ones to date have been to .00005" according to my indicator. Bear in mind that "good" gunsmithing has traditionally held this tolerance to .001". The point being it's plenty good. It's a solution to a problem that doesn't exist.
All the "nasties" associated with a poor chamber can be traced back to 4 fundamental topics:
1. Work holding
2. Tool rigidity
3. Spindle speed
4. Feed rate
Botch any of these and chambers come out like crap. If you took a plate of steel to any job shop machine shop worth anything and asked them to drill and ream 100 holes (or one hole for that matter) I can promise you no one is going to use a tap wrench or pair of vise grips to cram the reamer down the hole. It'll be in a collet, a tool holder, or some other rigid means of grabbing a tool. The work holding will be rock solid and the operation will be drama free.
Chambering a barrel is no different.
Reamers follow the existing hole. SO indicate where the bullet enters the bore for the first time (BIG HINT) and bore a concentric feature as close to that point from behind as reasonably possible. If the OD of the tool is engaging a concentric hole for about 1/3rd of its effective length it will continue to do so all the way to the zero point. Do that while securely grabbing that barrel and securely grabbing your reamer and chambers will suddenly become very simple operations to perform. You'll also find that 80 rpm is suddenly a bit silly as the tool wants to work somewhere between 40-85 surface feet when using medium carbon steels. 400 series stainless steels heat treated to around 25-28 rockwell operate in essentially the same range. (55-85)
That's somewhere between 400 and 475 rpm on a case with a .480 bolt face. I've done HUNDREDS of chambers like this with the same tool and it still cuts just fine. You won't burn it up, it's where the tool is designed to run.
Cutting oils:
They lubricate the cutting surface and mitigate chip weld. They are not snake oils that solve any of the 4 fundementals.
Tool chatter:
You go back to the 4 fundamentals. Solve the problem, don't put band-aids on it. I'm about as open minded as they come when it pertains to trying new stuff or doing the same thing differently to see if there's an improvement. Maybe I'm completely off base standing firm on the reamer principle. I certainly wish there was a way to accurately bore a chamber to finish dimensions as it would greatly lower my tooling overhead. (David Kiff makes a lot of money off me) I tried it once and it didn't work well at all.
If money were no object I'd opt for the extreme solution: A multi axis mill with a mile of feed range. I'd surface model the chamber and use an endmill to surface machine the chamber with a .00025" step. The code would be a mile long and the tool cycle times would be in the hours (days?) but it'd be bad ass as I could literlly use one tool to do the job.
Cost?
Around 3/4 of a million dollars is a conservative estimate. Tough to find a CNC with a 40-50 inch Z axis. I suppose you could do it with a horizontal but then you'd have to split the hairs over gravity causing the barrel to sag.
Hope this helped and none of my comments are offensive to anyone with differing opinion. It wasn't meant that way.
C
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: TheodoreKaragias</div><div class="ubbcode-body">
-Why isn't anyone using boring bars to cut the chamber?
If you present anyone highly skilled in manufacturing with a part having an existing bore and you ask them to cut another internal feature perfectly concentric with the bore, I guarantee that their first choice will not be an attempt to stuff some custom reamer down and existing hole. Within the firearms business, at least within the higher end or custom sector, this has become common practice largely because most gunsmiths that chamber barrels do not have the CNC lathe required to bore a chamber efficiently.
I would not be surprised to see a push towards bored chambers in the future. The advantages are significant, those being inherent concentricity and design flexibility. Nowadays, with indexable drills and carbide boring bars being common place, there is no reason not to bore chambers. A small investment in the process and some tooling by someone who already has a lathe is all that would be required to offer this service at a competitive price. Hmmm, maybe I ought to do it?
Is there anyone out there who currently bores chambers and is willing to share his experience with us?
</div></div>
I own a Doosan Mecatec 280N production slant bed turning center that I use exclusively for barrel work.
I can promise anyone here the idea of single pointing a chamber with a boring bar in any modern centerfire rifle cartridge is a daunting task. I'd rather have invasive dentistry minus the anesthesia. Solid carbide is pretty hard/tough stuff. Imagine a 300 Rem Ultra and how long it is. That's how long your boring bar has to be. Now you have to make it small enough to fit up in the throat. That means it's swept arc cannot exceed .297" on a 30 cal bore. The challenges only exponentially increase as the bullets (bore) gets smaller. Now ask where are the chips going to go? Chip evacuation is EVERYTHING in deep hole machining. Without it your burning visa cards on barrels, more boring bars, and Vicoden from India mail order. Nevermind that to get that boring bar to cut anything that resembles a decent finish its going to require significant depth of cut. Now your chip evacuation problem just got really intense. If you try making "squealer" cuts (there's a reason for the name) your going to end up with a boring bar that acts more like a stylus on a record player than a cutting tool.
PROPERLY set up there is NOTHING wrong with using a form tool to cut chambers. (which is all a chamber reamer really is)
The trick is the set up. I can promise anyone here or in the world that I can cut a chamber to a TIR (total indicated Runout) of .00025" or better. The best ones to date have been to .00005" according to my indicator. Bear in mind that "good" gunsmithing has traditionally held this tolerance to .001". The point being it's plenty good. It's a solution to a problem that doesn't exist.
All the "nasties" associated with a poor chamber can be traced back to 4 fundamental topics:
1. Work holding
2. Tool rigidity
3. Spindle speed
4. Feed rate
Botch any of these and chambers come out like crap. If you took a plate of steel to any job shop machine shop worth anything and asked them to drill and ream 100 holes (or one hole for that matter) I can promise you no one is going to use a tap wrench or pair of vise grips to cram the reamer down the hole. It'll be in a collet, a tool holder, or some other rigid means of grabbing a tool. The work holding will be rock solid and the operation will be drama free.
Chambering a barrel is no different.
Reamers follow the existing hole. SO indicate where the bullet enters the bore for the first time (BIG HINT) and bore a concentric feature as close to that point from behind as reasonably possible. If the OD of the tool is engaging a concentric hole for about 1/3rd of its effective length it will continue to do so all the way to the zero point. Do that while securely grabbing that barrel and securely grabbing your reamer and chambers will suddenly become very simple operations to perform. You'll also find that 80 rpm is suddenly a bit silly as the tool wants to work somewhere between 40-85 surface feet when using medium carbon steels. 400 series stainless steels heat treated to around 25-28 rockwell operate in essentially the same range. (55-85)
That's somewhere between 400 and 475 rpm on a case with a .480 bolt face. I've done HUNDREDS of chambers like this with the same tool and it still cuts just fine. You won't burn it up, it's where the tool is designed to run.
Cutting oils:
They lubricate the cutting surface and mitigate chip weld. They are not snake oils that solve any of the 4 fundementals.
Tool chatter:
You go back to the 4 fundamentals. Solve the problem, don't put band-aids on it. I'm about as open minded as they come when it pertains to trying new stuff or doing the same thing differently to see if there's an improvement. Maybe I'm completely off base standing firm on the reamer principle. I certainly wish there was a way to accurately bore a chamber to finish dimensions as it would greatly lower my tooling overhead. (David Kiff makes a lot of money off me) I tried it once and it didn't work well at all.
If money were no object I'd opt for the extreme solution: A multi axis mill with a mile of feed range. I'd surface model the chamber and use an endmill to surface machine the chamber with a .00025" step. The code would be a mile long and the tool cycle times would be in the hours (days?) but it'd be bad ass as I could literlly use one tool to do the job.
Cost?
Around 3/4 of a million dollars is a conservative estimate. Tough to find a CNC with a 40-50 inch Z axis. I suppose you could do it with a horizontal but then you'd have to split the hairs over gravity causing the barrel to sag.
Hope this helped and none of my comments are offensive to anyone with differing opinion. It wasn't meant that way.
C
Re: EDM chambering
Afterthought-
Your boring idea could work. (sorta)
First, cram a drill in there to get stuff out of the way. Go in with a boring bar and get something that resembles a concentric "general shape" of the chamber.
Then ID grind the bore. Live tooling and pressurized coolant through the stone should make a nice finish. Just have to dance with it a bit to figure out your stone wear. With all the modern abrasives out there (something I'm not real educated on or experienced with) I'd be willing to bet there's something that would work well enough.
Now just to pony up the big coin for a turning center with live tooling. (I'd bet you could be 5 deep on every chamber reamer PTG makes for the cost of one turning center with live tooling) Now balance that with the increased cycle times, the filtration your going to have to use to ensure the abrasive soup coming off the stone doesn't get on your bedways and sitting down and programming every operation for every chamber/variant out there.
I'd still edge my bet that reamers are here to stay and THANK GOD (David) for it!
Afterthought-
Your boring idea could work. (sorta)
First, cram a drill in there to get stuff out of the way. Go in with a boring bar and get something that resembles a concentric "general shape" of the chamber.
Then ID grind the bore. Live tooling and pressurized coolant through the stone should make a nice finish. Just have to dance with it a bit to figure out your stone wear. With all the modern abrasives out there (something I'm not real educated on or experienced with) I'd be willing to bet there's something that would work well enough.
Now just to pony up the big coin for a turning center with live tooling. (I'd bet you could be 5 deep on every chamber reamer PTG makes for the cost of one turning center with live tooling) Now balance that with the increased cycle times, the filtration your going to have to use to ensure the abrasive soup coming off the stone doesn't get on your bedways and sitting down and programming every operation for every chamber/variant out there.
I'd still edge my bet that reamers are here to stay and THANK GOD (David) for it!
Re: EDM chambering
Thank you for sharing your experience with us C. Dixon. I must say that I was pleased to see that your second post showed deeper consideration of the topic than did your first post.
Roughing the chamber with one or more indexable drills should be considered standard procedure. Likewise, there is nothing to suggest that a constant cross section boring bar must be used. In fact, the bar should quite obviously have as much section as possible over as much of its length as possible, likely making it a custom tool while detracting as little as possible from its usefulness as a multi-chamber tool.
I think the the best point you made was in regards to chip evacuation. That is a HUGE issue. I would attempt to address this issue by potentially back boring the finish cut, in effect pushing the chip towards the breech and thus not dragging it over the finished chamber surface. What's more is that CNC offers the ability to custom tailor a cycle for chip clearing. I would not be too concerned about finishing with extremely light cuts simply because the tool, feed, speed, coolant, workholding, etc combinations definitely exist. More challenging boring applications are routinely performed in other industries, namely aerospace and medical, and with more difficult materials. Proper tool, coolant, and workholding could be quickly identified. Tool path (cycle) design, speed, and feed will likely be the bulk of the work.
A few years ago while developing a bolt action for use in classic hunting rifles, I was reaming chambers in a Nakamura Slant 1 CNC turning center. I found this to be unnecessarily difficult. Unfortunately, I did not pursue the boring process at that time. Months later, having sold the turning center, I hired and extremely qualified manufacturer to chamber some barrels for me. They had never done any firearms related work in the past but I knew that would not matter in this case as these guys were well equipped, both with machines and brains to support. When I handed both a roughing and finishing chamber reamer to them, they look at me and asked, "Do we really have to use this?" In the end, they used the reamers simply because they only chambered two or three barrels for me. Had the quantity been higher, or if this were to become a regular thing, I am quite certain these guys would have been motivated to develop a boring process. For me, this illustrated an interesting point. Contact manufactures often have an extremely diverse breath of knowledge and will often solve problems in non-conventional ways, bucking the conventional wisdom.
I will certainly explore this in the future.
Thank you for sharing your experience with us C. Dixon. I must say that I was pleased to see that your second post showed deeper consideration of the topic than did your first post.
Roughing the chamber with one or more indexable drills should be considered standard procedure. Likewise, there is nothing to suggest that a constant cross section boring bar must be used. In fact, the bar should quite obviously have as much section as possible over as much of its length as possible, likely making it a custom tool while detracting as little as possible from its usefulness as a multi-chamber tool.
I think the the best point you made was in regards to chip evacuation. That is a HUGE issue. I would attempt to address this issue by potentially back boring the finish cut, in effect pushing the chip towards the breech and thus not dragging it over the finished chamber surface. What's more is that CNC offers the ability to custom tailor a cycle for chip clearing. I would not be too concerned about finishing with extremely light cuts simply because the tool, feed, speed, coolant, workholding, etc combinations definitely exist. More challenging boring applications are routinely performed in other industries, namely aerospace and medical, and with more difficult materials. Proper tool, coolant, and workholding could be quickly identified. Tool path (cycle) design, speed, and feed will likely be the bulk of the work.
A few years ago while developing a bolt action for use in classic hunting rifles, I was reaming chambers in a Nakamura Slant 1 CNC turning center. I found this to be unnecessarily difficult. Unfortunately, I did not pursue the boring process at that time. Months later, having sold the turning center, I hired and extremely qualified manufacturer to chamber some barrels for me. They had never done any firearms related work in the past but I knew that would not matter in this case as these guys were well equipped, both with machines and brains to support. When I handed both a roughing and finishing chamber reamer to them, they look at me and asked, "Do we really have to use this?" In the end, they used the reamers simply because they only chambered two or three barrels for me. Had the quantity been higher, or if this were to become a regular thing, I am quite certain these guys would have been motivated to develop a boring process. For me, this illustrated an interesting point. Contact manufactures often have an extremely diverse breath of knowledge and will often solve problems in non-conventional ways, bucking the conventional wisdom.
I will certainly explore this in the future.
Re: EDM chambering
That was a great read, thanks for all the discussion. While I don't have enough knowledge to fully understand all of the lingo, I am learning.
That was a great read, thanks for all the discussion. While I don't have enough knowledge to fully understand all of the lingo, I am learning.
Re: EDM chambering
Chad,
Boring such small diameter holes is going to save no time over piloted 3 flute roughers, by the time you pick up the chamber with the finisher I doubt you've gained anything precision or production wise..Grinding, unless it was some sort of CBN form grinding slug, haha..What I have been looking at is the ultra rapid pecking cycles of certain drilling operations which has resulted in better parts, and they cut just as quickly or quicker. I'll have to find the video..
Chad,
Boring such small diameter holes is going to save no time over piloted 3 flute roughers, by the time you pick up the chamber with the finisher I doubt you've gained anything precision or production wise..Grinding, unless it was some sort of CBN form grinding slug, haha..What I have been looking at is the ultra rapid pecking cycles of certain drilling operations which has resulted in better parts, and they cut just as quickly or quicker. I'll have to find the video..
Re: EDM chambering
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: __JR__</div><div class="ubbcode-body">Chad,
Boring such small diameter holes is going to save no time over piloted 3 flute roughers, by the time you pick up the chamber with the finisher I doubt you've gained anything precision or production wise..Grinding, unless it was some sort of CBN form grinding slug, haha..What I have been looking at is the ultra rapid pecking cycles of certain drilling operations which has resulted in better parts, and they cut just as quickly or quicker. I'll have to find the video.. </div></div>
The path this thread has taken with the proposal by TK to use a different technique than the norm is interesting. JR, is the doubt you've expressed above a result of practical observation after having tried the method TK has mentioned?
Given how crucial concentricity of chamber to bore is for extreme accuracy I would have thought someone would have already tried more modern techniques and machining practices to this issue.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: __JR__</div><div class="ubbcode-body">Chad,
Boring such small diameter holes is going to save no time over piloted 3 flute roughers, by the time you pick up the chamber with the finisher I doubt you've gained anything precision or production wise..Grinding, unless it was some sort of CBN form grinding slug, haha..What I have been looking at is the ultra rapid pecking cycles of certain drilling operations which has resulted in better parts, and they cut just as quickly or quicker. I'll have to find the video.. </div></div>
The path this thread has taken with the proposal by TK to use a different technique than the norm is interesting. JR, is the doubt you've expressed above a result of practical observation after having tried the method TK has mentioned?
Given how crucial concentricity of chamber to bore is for extreme accuracy I would have thought someone would have already tried more modern techniques and machining practices to this issue.
Re: EDM chambering
I've attempted to single point bore a chamber before. It was (to some degree) successful.
Concerns:
1. How does one know (really know) that the freebore and throat are machined to the desired specification?
2. How does a single point tool manage the interrupted cut when machining the throat? A reamer does a "so so" job. part of a barrel's break in is eroding the nicks off the throat by shooting it. Will this be reduced or increased?
3. I have concerns over the surface finish when its all done. Stepped diameter bars are fine, but I still suspect the tool is going to sing like a church choir.
4. How much time you going to invest into a complete unknown? (Be nice if you could get a govt grant to pay for the research.)
5. What happens when/if something goes wrong and you get someone hurt? The shark lawyers will eat your ass. Liability these days is a real biche. Especially with devices who's primary function is to kill people.
I'm skeptical because from my chair there isn't anything wrong with a form tool. (chamber reamer) Surface finish is good. Accurate chambers can be machined in a time efficient manner, and the tooling is affordable.
In all honesty I've put myself in an awkward position. How do I describe what I'm doing while managing proprietary/intellectual property concerns, not sounding like a pompous A-hole, and still sound convincing enough to not be written off as full of crap?
I can tell you this. While at Nesika I didn't have many rules. I had probably the longest leash of anyone there. Believe me, I used it. In reflection, it ended up being my little test tube for various ideas. Glen Harris, Mike Allen, and Cyle Miller were all very, very supportive and open to breaking through boundaries in the interest of doing a better job.
A perfect example would be the bedding work I do on stocks. The lineage can be traced back to Nesika. Go to the website and see the similarities. As I've often said I'll never be guilty of having an original thought.
Nesika only builds actions now. I'd like to think I'm passing on at least a small portion of "the old days". (or maybe I'm just full of chit)
Figuring out a way to ensure barrel bores are concentric where the bullet enters and leaves was the first big step. Nesika had this wired before I ever got there. It made sense and I went on to make some small incremental improvements during my tenure there. From 2006-2009 I was in the middle east with plenty of nights to ponder this stuff. When I got home I began "chapter 2" in earnest. I explored my ideas and stumbled onto something rather novel (in my humble opinion anyway) I've done enough barrel jobs now to have some accurate feedback. It's working and I'm quite satisfied and customers certainly seem to have nice comments about it as well. The best solutions are often the least complex.
That being said I stand firm that there's nothing wrong with reamers- when used to potential. Besides, what the hell would we do without David Kiff?
I've attempted to single point bore a chamber before. It was (to some degree) successful.
Concerns:
1. How does one know (really know) that the freebore and throat are machined to the desired specification?
2. How does a single point tool manage the interrupted cut when machining the throat? A reamer does a "so so" job. part of a barrel's break in is eroding the nicks off the throat by shooting it. Will this be reduced or increased?
3. I have concerns over the surface finish when its all done. Stepped diameter bars are fine, but I still suspect the tool is going to sing like a church choir.
4. How much time you going to invest into a complete unknown? (Be nice if you could get a govt grant to pay for the research.)
5. What happens when/if something goes wrong and you get someone hurt? The shark lawyers will eat your ass. Liability these days is a real biche. Especially with devices who's primary function is to kill people.
I'm skeptical because from my chair there isn't anything wrong with a form tool. (chamber reamer) Surface finish is good. Accurate chambers can be machined in a time efficient manner, and the tooling is affordable.
In all honesty I've put myself in an awkward position. How do I describe what I'm doing while managing proprietary/intellectual property concerns, not sounding like a pompous A-hole, and still sound convincing enough to not be written off as full of crap?
I can tell you this. While at Nesika I didn't have many rules. I had probably the longest leash of anyone there. Believe me, I used it. In reflection, it ended up being my little test tube for various ideas. Glen Harris, Mike Allen, and Cyle Miller were all very, very supportive and open to breaking through boundaries in the interest of doing a better job.
A perfect example would be the bedding work I do on stocks. The lineage can be traced back to Nesika. Go to the website and see the similarities. As I've often said I'll never be guilty of having an original thought.
Figuring out a way to ensure barrel bores are concentric where the bullet enters and leaves was the first big step. Nesika had this wired before I ever got there. It made sense and I went on to make some small incremental improvements during my tenure there. From 2006-2009 I was in the middle east with plenty of nights to ponder this stuff. When I got home I began "chapter 2" in earnest. I explored my ideas and stumbled onto something rather novel (in my humble opinion anyway) I've done enough barrel jobs now to have some accurate feedback. It's working and I'm quite satisfied and customers certainly seem to have nice comments about it as well. The best solutions are often the least complex.
That being said I stand firm that there's nothing wrong with reamers- when used to potential. Besides, what the hell would we do without David Kiff?
Re: EDM chambering
C,
I could see a guy having to 100% every aspect of the chamber if done single point, not very productive..Like you the problems I don't see as much in body, shoulder, neck, but thereafter..You might be ok on larger bores, shotguns, but once you're under 30cal you're in new territory, dealing with tool deflection due to the tool being small and delicate, and at the end of the day the throat must be in relation to the bore concentricity at that junction. That's why I said CBN slug or hell if a guy could finish with a piloted hone rather. So until then I'll stick with Kiff and his outstanding form tools..
C,
I could see a guy having to 100% every aspect of the chamber if done single point, not very productive..Like you the problems I don't see as much in body, shoulder, neck, but thereafter..You might be ok on larger bores, shotguns, but once you're under 30cal you're in new territory, dealing with tool deflection due to the tool being small and delicate, and at the end of the day the throat must be in relation to the bore concentricity at that junction. That's why I said CBN slug or hell if a guy could finish with a piloted hone rather. So until then I'll stick with Kiff and his outstanding form tools..
