I have always used a lathe with a foot brake when turning threads. On a lathe Without a foot brake running at low speed of say 60 rpm, how quickly will spindle stop turning using say an 8" chuck. Any guesstimates? If I am going to be threading to a shoulder do I need to up the ante and get the G0709 with foot brake? Thread in reverse? Opinions?
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Gunsmithing New Lathe
- Thread starter x ring accuracy
- Start date
I thread up to a shoulder without a brake, dont worry about when the spindle will stop, you just have to be quick and crank out the crosslide and disengage the half nut at the same time. I dont think I would use a brake if I had one for threading, however I do want a brake on my next lathe just because it can get annoying to wait for the spindle to stop in other circumstances.
And just to note, the spindle takes just as long or sometimes it seems like longer to stop when running at a low speed. However, if you slip the gear selector in between into neutral it will stop pretty quickly, just the inertia from all the gears and everything keeps it spinning for awhile when in gear.
ETA. I should note I usually thread at either 190 or 300rpm for 24/28 tpi
And just to note, the spindle takes just as long or sometimes it seems like longer to stop when running at a low speed. However, if you slip the gear selector in between into neutral it will stop pretty quickly, just the inertia from all the gears and everything keeps it spinning for awhile when in gear.
ETA. I should note I usually thread at either 190 or 300rpm for 24/28 tpi
The last time I threaded a muzzle with 24 TPI threads, I was running at 500 RPM, and did not use a footbrake (admittedly, I did "cheat" and leave myself a 0.050" undercut at the shoulder). As Jon says, it's just a matter of coordinating two relatively simple actions... and paying close attention to what the f*** you are doing! I emphasize this latter point because failure to do so is what usually causes me to lose a threading insert.
And probably .600" of barrel length too.
A DRO does help here, I place the tool with the compound zeroed about .01 from the shoulder and zero the dro. I try not to let the dro get to zero when I back out, usually in the .02 and under range that way it's safe, and still plenty close to the shoulder with no relief.
Galaxy S3 on tapatalk
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Thank you GR for your comments. My businesses, specially Grizzly, are like my babies and someone makes unfair comments about them - I respond like an upset parent. If there is truth to stuff, we try and fix it because we do not like bad reputation.
By the way, I have lived here in Bellingham for 30 years and don't know of a place that would be better. Mountains on one side, salt water, boating and fishing within a few minutes, and lots of land in the county for shooting. Not too hot in the summer, not too cold in the winter and the rain keeps the city clean
Thanks for the business.
Thanks everyone for your input. I couldn't agree with you more PapaGriz having to sell my business was VERY difficult, like letting go of your kids when they out grow you. There is a lot of misinformation on the Internet and you have every right to, and should, set people straight.
500 RPM threading?.....good god man, that takes nerves of steel
Okay, this makes me handicap. I thread at 90 RPM to avoid any mistakes. Then I heard someone say 250 RPM, and thought, wow!!! F**king badass there!! Now I hear 500 RPM. Please, please, let's see a short video of this. I'll have something to rub one off to in the shower to tonight. My nerves wouldn't allow for that unless I had 2 inches of relief after the cut ends. Holy crap!
You guys know damn well what would happen if I tried to film this - about two seconds after the camera is turned on, I'd massively crash the insert (as a side note, a friend once attempted to take a video of me jumping a mountain bike off the roof of my house with approximately the same results).
Regardless, it's not that tough to do with my machine as long as my head is focused on the task. Obviously, with a 0.800" 24 TPI tenon taking a bit less than two seconds from start to finish, it does require some attention, and as I stated previously, I usually cut a 0.050" undercut which yields a surprisingly large margin for error.
Regardless, it's not that tough to do with my machine as long as my head is focused on the task. Obviously, with a 0.800" 24 TPI tenon taking a bit less than two seconds from start to finish, it does require some attention, and as I stated previously, I usually cut a 0.050" undercut which yields a surprisingly large margin for error.
STR Im with you I heard people talking about threading at high speeds so I thought I would try it. I couldnt even reliably engage the halfnut at 500 rpm let alone think about disengaging the threading tool anywhere near a shoulder or critical dimension. Ainjest made a high speed threading attachment for the colchesters but I have read it had problems with repeatability and was big bucks. The HLVH Hardinge has a quick release threading setup which would probably allow for higher RPM threading I have also seen sliders that people have fabricated to allow a quick tool withdrawal without cranking the crosslide. I have though about fabbing one up but my threads look good with slower speeds and HS steel tooling so if it aint broke
I've been running threads at 250 rpm and it seems easy enough. I decided to get cocky and try 500. Not too bad, but everything happens twice as fast--so fast, I'm not exactly sure what happened here, but I'm thinking I ran the cross slide the wrong way. Luckily the lathe stalled and the toolpost rotated/slid in its mount and I didn't break the half-nuts. This was a practice tenon with 4140 bar stock and a modified cutoff tool doing the threading.
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I've been running threads at 250 rpm and it seems easy enough. I decided to get cocky and try 500. Not too bad, but everything happens twice as fast--so fast, I'm not exactly sure what happened here, but I'm thinking I ran the cross slide the wrong way. Luckily the lathe stalled and the toolpost rotated/slid in its mount and I didn't break the half-nuts. This was a practice tenon with 4140 bar stock and a modified cutoff tool doing the threading.
Yikes! Crash n burn. Glad you and the lathe are ok.
Im a chicken and relatively new to this but I use 70rpm and occasionally step it up to 200rpm when im feeling ballsy or using a large relief.
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It spins pretty fast. I engage the half-nuts with about an inch or more of lead before the work piece, but I've never missed a mark. I don't have but 2 lathes to compare: a 1966 SB13 and a Chinese mini lathe, but the SB is very precise and solid in its engagement compared to the mini.
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FYI - when lathes are new, the levers to engage the half nuts are usually tight, so that slows your response down a bit.
For those guys wishing to run threading at high speeds, you need a well maintained machine and good concentration. A phone ring or a dog bark or someone calling you can distract you enough to make it an expensive experience! There are well accomplished guys out there that do this all the time, but remember that a crash into the chuck will do all kinds of little damage that you sometimes cannot see. For example, a crash could affect the spindle bearings which could affect accuracy.
For those guys wishing to run threading at high speeds, you need a well maintained machine and good concentration. A phone ring or a dog bark or someone calling you can distract you enough to make it an expensive experience! There are well accomplished guys out there that do this all the time, but remember that a crash into the chuck will do all kinds of little damage that you sometimes cannot see. For example, a crash could affect the spindle bearings which could affect accuracy.
The fun part is when you get your rhythm on external threads, then you go to true an action and have to force your brain to remember to turn the cross slide the other direction, that's an even more expensive mistake, luckily knock on wood, haven't made that yet
Galaxy S3 on tapatalk
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220 is comfortable to me, but every once in a while i will go upwards of 300ish. I see no difference in thread finish though. Lee
Use left handed tool and cut them in reverse then you don't have to worry about any of that mess. You have the entire length of the bed to disengage it
A relief is REQUIRED for this method though, I prefer no relief, just my preference though.
My mentor beat into my head "OLD MAN SLOW" when threading so I am comfy at 40 rpm. Some guys I know use 125 or so. I cringe but wish them well. As Papagrizz said, crashes are bad news. My mentor also would cut a tennon major diameter at 40 rpm and the slowest feed rate on the machine......I would go read war and peace and have time to see it come close to the shoulder. GAWD! As we all do, we learn from others, pick and choose what we take from them. But threading at high speed is more than my heart can take
I possess one of these HLVH Hardinge units. You don't pull the tool until the carriage stops, there is no thread dial you set the carriage stop to bump it out of gear at the shoulder, and it is very precise. Once it stops, you reverse the carriage after pulling back the compound. When you clear the work, stop the carriage, go forward with the compound, feed in the new amount and re-engage the carriage. It is very quick you can cut a whole tenon in five minutes or less. Only drawback is you cannot take huge deep cuts like the big grizzly can. The upside of the faster speeds is that I can use a preform carbide tool, at speeds that give a good finish. The downside is, Bad Shit happens Real Quick if you move the wrong lever at the wrong time. Ask me how I know that !!!
I'll video the tenon next time I'm cutting and post it.
My thread dial is just a tad off, but I like it that way. I can lightly tug up on the half-nut lever right at the line and it engages just a little past the line. I don't know if this is by design (I had to get the thread dial off ebay when I purchased the lathe).
Here's the dial at 500 rpm spindle speed with the change gears set to 16tpi:
Thread dial at 500 rpm set for 16 tpi. - YouTube
Here's the dial at 500 rpm spindle speed with the change gears set to 16tpi:
Thread dial at 500 rpm set for 16 tpi. - YouTube
Shattering cut off tool
You really have to watch out for those exploding cutoff tools. I had one take a good little chunk of ear off in the past.
You really have to watch out for those exploding cutoff tools. I had one take a good little chunk of ear off in the past.
I've been running threads at 250 rpm and it seems easy enough. I decided to get cocky and try 500. Not too bad, but everything happens twice as fast--so fast, I'm not exactly sure what happened here, but I'm thinking I ran the cross slide the wrong way. Luckily the lathe stalled and the toolpost rotated/slid in its mount and I didn't break the half-nuts. This was a practice tenon with 4140 bar stock and a modified cutoff tool doing the threading.
Anyone interested in a 15 x 50 lathe in great condition?
This one came out my CNC lab downstairs and was used gently for a few years, a few hours a week for prototyping only. Excellent condition and has a Fagor DRO on it that has less than 5 hours of use on it before we switched out lathes. Made in Taiwan and sold for around $14K + $1500 for DRO before the factory raised the price 20% and we discontinued. Will sell for $9.5K. Not the best for through-the headstock gunsmithing as the headstock is long, but nice lathe with all the accessories.
This one came out my CNC lab downstairs and was used gently for a few years, a few hours a week for prototyping only. Excellent condition and has a Fagor DRO on it that has less than 5 hours of use on it before we switched out lathes. Made in Taiwan and sold for around $14K + $1500 for DRO before the factory raised the price 20% and we discontinued. Will sell for $9.5K. Not the best for through-the headstock gunsmithing as the headstock is long, but nice lathe with all the accessories.
The Z series are top notch, I have one and it runs true. Bump for a smokin' deal. If I only had the room......Anyone interested in a 15 x 50 lathe in great condition?
This one came out my CNC lab downstairs and was used gently for a few years, a few hours a week for prototyping only. Excellent condition and has a Fagor DRO on it that has less than 5 hours of use on it before we switched out lathes. Made in Taiwan and sold for around $14K + $1500 for DRO before the factory raised the price 20% and we discontinued. Will sell for $9.5K. Not the best for through-the headstock gunsmithing as the headstock is long, but nice lathe with all the accessories.
