Gunsmithing Help using PTG Range rods

S

SSC

Sergeant
Commercial Supporter
Full Member
Minuteman
Mar 4, 2008
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0
La Grange, TX
www.scoutsupplycompany.com
#1
Okay so I am trying to start using the PTG rods, so I wanted to try it out on a factory barrel to see how it comes out.
After I get everything dialed just right, i pull the rod and re-install to see if everything reads the same. I pulled and re-installed 15-20 and only got the same reading one time. My question is how do you know when the rod is seated corrected?

my setup is a grizzly g4003g, 4 jaw chuck with copper wire wrapped around the jaws, spider on the back.

also when the lathe is under power the front indicator reads .001 off of where I had it zeroed.
 
#2
Re: Help using PTG Range rods

this is one of the main reasons that i am going away from the tapered range rod method and starting to use the grizzly rod method.

chances are that the crown isn't perfectly perpendicular to the bore and the rod is being bent when the taper hits.
 
#3
Re: Help using PTG Range rods

Call me wreckless/crazy:

Try sticking a long stylus indicator up the breech. Time it up and make some chips.

If you cut it on size I bet it shoots. Test TIR by sticking your reamer in the finished chamber. Seat it to full depth. Stick an indicator on the shank and see what you end up with.

Good luck regardless.

C.
 
#5
Re: Help using PTG Range rods

BIG OL PLUS 1 on what Chad Said...... Also on a taper pilot you are not locating or obtaining your reading from very much and are still not near the throat are of where the Chamber will be....

Same issue on Race Engine here....On a Serdi Valve machine it has a long carbide shank that goes all the way through the guide then floats on air to obtain its alignment
Thes you have the Sunnen Valve machine it uses a tapered pilot to locate on a portion of the valve guide to center and located and axial alignment...

You can recut the seats behind a Sunnen machine and will always see the runout and seal the same after a Serdi machine runs them.
 
#6
Re: Help using PTG Range rods

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: GLOWWORM</div><div class="ubbcode-body">Also on a taper pilot you are not locating or obtaining your reading from very much and are still not near the throat are of where the Chamber will be....</div></div>

i disagree with this if you are indicating in two places on the rod.
 
#8
Re: Help using PTG Range rods

1/8 carbide ball works great.

You want the long stylus to get up past the bellmouth of the breech end from lapping. So long as you have an inch of reach your golden as you'll be in qualified material.

Also remember the spring tension on a test indicator is quite small. Unless your buzzing that barrel hard in the spindle it should never catch. You NEVER run an indicator on a part with it running. The vibration caused by surface finish can damage the tool.

Always run the chuck by hand. Even on a CNC.

Coaxial indicators are able to run this way, but that's a whole different kind of tool.
 
#9
Re: Help using PTG Range rods

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: SSC</div><div class="ubbcode-body">when you stick the indicator in the breech it won't be able to reach the rifling. but if I take a reading off the chamber it will only be as on it was at the factory, right? </div></div>

If your barrel has already been chambered you stuck with what the guy ahead of you did.

A reamer is a form tool. It, like a drill, will take the path of least resistance. If your chamber is goofed, it's going to continue goofing it.

If it's right, then it should follow what is there and come out Jonny on the spot.

In ONE instance in 10 years I have been able to fix a goof. I had a woops on a barrel once by sticking a bad wear offset in my CnC control. It put the reamer off center by about .01". I began chambering and noticed weird chit going on almost right away once the shoulder started cutting. The reamer was trying to act like a boring bar for all purposes.

They suck at it btw.

I got my poop in a group and decided to continue. I mean the barrel was already toast so what's to lose at this point right?

Well, it worked. The ass end of the case was big enough to swallow up the runout and the chamber came out awesome. Less than a couple 10ths runout.

I got lucky. I base my "luck" on a 40+lb custom reamer holder than I made from scratch for my CNC. I also base it on a tool turret that weighs more than most of the manual machines being used by smiths on this site.

My lathe is over 9000lbs when its gassed up with coolant.

MASS helps.

Good luck.

C.

BTW, the gun hammered.
 
#10
Re: Help using PTG Range rods

Thanks. I have always been afraid of the ball catching a land and showing me how fast $200 can fly out the window. You need to re cal the indicator more often with all the groove hopping?
 
#11
Re: Help using PTG Range rods

ditto on Chads setup.

I've chambered so many barrels that way I've worn out an Interapid long stem indicator and had it rebuilt once and planning on wearing it out again. In 28 years I've never come across a better way to set a barrel up and I've tried.

No need for rods and they will give you false readings.
 
#13
Re: Help using PTG Range rods

Not me. I use a four screw spider on the out board and inboard of the headstock. I use a snug fitting bushing in the muzzle to indicate on and about 2.750" in on the chamber end. If the barrel is too short I have precision made bushings and a few tricks for alignment inside the headstock.

These pics are from my Haas TL-1
indicatechamber.jpg


indicatemuzzle.jpg
 
#14
Re: Help using PTG Range rods

I use 16C collets and a hydraulic chuck.

up 1000lbs of clamping pressure if I want it. Rarely exceed 200lbs though.

I also hold onto both ends. My muzzle end setup is quite simple.
my CNC lathe goes to 7000rpm. When running this high (never do btw) you can lay your hand on the machine and hardly tell its even running.

That suggests to me the spindle bore is pretty dead nuts.

With that in mind I have a sleeve arrangement that I made with 5C collets to hold onto the muzzle end of the barrel. The whole contraption gets shoved up the ass end of the spindle and I'm done. Indicate the breech/muzzle (whatever it is I'm working on) and go for broke.

Works awesome. Quick, precise, repeatable, and best of all, the buggers sure seem to shoot nice once they are all done.

Just took me the better part of 6 figures to get it. . .

DSC_0003.jpg


DSC_0001-1.jpg


DSC_0040.jpg
 
#15
Re: Help using PTG Range rods

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">With that in mind I have a sleeve arrangement that I made with 5C collets to hold onto the muzzle end of the barrel. The whole contraption gets shoved up the ass end of the spindle and I'm done. Indicate the breech/muzzle (whatever it is I'm working on) and go for broke.</div></div>

Chad - one quick question - with a setup like that, (on the 5C collet end) you simply run true to whatever the OD is regardless of the concentricity of the bore in relationship to the OD - is that correct or am I not following you?
 
#16
Re: Help using PTG Range rods

Your 100% correct!

Crazy huh?

If you bore the chamber prior and KNOW your reamer has concentric engagement and tangent feed then I fail to see how it affects anything. It kicked the door open the first year or so as it was pretty different from the norm. I took quite a bit of crap for it actually. Still do at times. Everything from halfassin to production grade work.

Garret was even pretty skeptical the first few times he ran them.

-till he started measuring TIR, looking a surface finish, and shooting them.

He's pretty convinced now and we often chuckle at the over engineered/complicated practices we had to use at Nesika/Dakota.

I was nervous the first few times. Now it'd kill me to do it any other way. We don't even use pilots anymore! Sucks cause I spent almost a thousand dollars on the dern things. Got every size from 17 to 338.

Guns are hammerin pretty well these days.

C.

 
#17
Re: Help using PTG Range rods

Wait...I am sure that I'm misunderstanding here...

How does the process account for the potential lack of concentricity between the OD of the barrel and the actual center of the bore?
 
#18
Re: Help using PTG Range rods

Pretty much the same thing here. I indicate the throat and don't use pilots. The reamer will follow the bored hole to the point that you indicated. I have done it every way, between centers, range rods, gordy rods, ect. I have never been able to tell that the more complicated ways shoot any better. Try it. You'll see. Chad and Dave know what there doing.
 
#19
Re: Help using PTG Range rods

It doesn't. Because the bullet doesn't care what the barrel is doing 24,25,26,27. . . Inches later.

if concentricity is really that bad then no barrel should shoot anyway.

Your splitting hairs one way by trying to make a banana straight while chambering. Prolly works, but you give up something that I'm not willing to. Work holding, surface area, clamp force, and rigidity during machining.

I'm splitting my hairs a different way. I focus on concentricity to where the bullet engages the throat. A collet offers almost 100% part captivation. Three/four brass tipped screws don't. That's workholding power I don't want to give up.

Can you build an accurate gun this way? Sure you can. Id be an idiot to suggest otherwise. Is it more accurate/predictable/reliable than what I'm doing? I've yet to see it and I build on very broad variety of calibers.

What I'm doing is unconventional. 90% of my practices aren't mainstream.
Still works and in some ways far exceeds what competitors can deliver. Call it better,worse, or crazy. I call it an awakening that I wished id of figured out 10 years ago.

Happy turkey day. I think were goin archery shootin in the morning. Got the bratty daughter a bow tech razor tonight. She's lovin it!

C.
 
#23
Re: Help using PTG Range rods

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">Your 100% correct!

Crazy huh?</div></div>

Not at all Chad - I've been doing a similar thing in a Hardinge Cobra for about 2 years now but didn't know anyone else using the technique. I didn't worry about the other end either but that's considered "unconventional" - that's why I asked.
 
#24
Re: Help using PTG Range rods

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: C. Dixon</div><div class="ubbcode-body">Flip around, indicate, and run.

I guess I neglected to mention that I have a collet chuck that acts like a 4 jaw.

I can indicate with this chuck just like a spider/buck chuck.

C.</div></div>

So, with your process for threading the muzzle, the suppressor mount would end up being concentric to the bore and not the OD of the barrel?
 
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