Necessary tooling for Indicating a barrel?

[shawnba67]

So i bought a lathe and ive been self teaching in my free time, thank goodness scrap is next to worthless so it hasnt cost me much yet. I bought a couple 22rf barrels of and id like to try my hand threading, crowning and cutting a chamber. I do not have any way of indicating that bore. what would the minimum tooling needed(i have 2. 0005 test indicators)
Am i correct in needing 2 range rods and 2 sets of bushings? One for chamber and one for muzzle end i will be using a spider at the muzzle end
I do not have a steady rest. Have room through spindle for a barrel thanks for any advice

 

[sloughfoot]

I would hope you have a dial indicator? At least?

 

[jcj54]

2 EA. .2150, .2160, .2170 pin gage, 2 .0005 dial indicators, spier and 4 jaw chuck.
use pin gages that are the closest fit to the bore. I have seen bores as small as .215 and as large as .218 on .22 rf barrels.

 

[1911ly]

The barrel need to be centered on the bore. Not on the out side of the barrel. A live center on the tail stock end works if you are profiling a barrel. The head stock end can be done many ways depending on the lathe you have. If you have a large enough chuck or backing plate they make a barrel holder that fits threw the tail stock and you indicate of the inside of your barrel or use a tight pin gauge in the bore to indicate off of. It looks like a length of pipe with 4 bolts on each end that you adjust for centering. It will allow the end of the barrel to be open for crowning and chambering.

Youtube some barrel threading videos and you will get the ideal. It's not a job for a novice right off the bat. But if you have some scrap and patience you can learn to do it.

If the barrel flex's you will have chatter or there will be a lot of spring in your cut. Spring cut = make a cut and make another pass at the same amount, if it is still removing metal your barrel is flexing. So a steady rest might be needed if you are getting chatter or springing in your cut.

Larry

 

[PGRChaplain]

What Larry said^^^^^^^^^! Get some black pipe and practice Threading on that, it's cheap and cuts easy.

 

[foxmustang]

You'll need something to undercut the threads as well. As your threading tool won't cut right to a square shoulder. A good carbide threading tool will go along way versus a high speed steel one. I'd also recommend getting a Machinery Handbook. It has just about everything you would need to know about thread tolerances for minor and major diameter, as well as class of fits plus ALOT more.

 

[AllenM]

Don't waste your money on range rods and bushings. You will need a fixture that will allow you to adjust adjust the bore concentricity, but you know that. Range rods were nothing but a source of frustration to me and I never really felt confident with them.
I have 3 ways I use to align a barrel to the bore, this is what I use the most. I have settle on this fixture and a special test indicator with a 2.5" needle.








Once you get this figured out the threading is pretty easy. But correct tooling is important there too

 

[shawnba67]

Thank you very much guys, with extra thanks to Allen for the pictures!
Am i correct in assuming that the needle jumps around alot going over the rifling and you would be watching for the edges of travel being the same? or do you bore it smooth(if its bored i have no idea how that can work)
Secondary question
I cant afford a 1/2x28 thread fit guage if i threaded a piece from say .510 and cut it with the threading tool to .498 max diameter assuming i threaded correctly would that basically be a good test guage? (I dont have the mating pieces to check fit with very often so wanted a near perfect tool to fit against. )

 

[AllenM]

no you do not bore the rifling out. the needle moves but you can measure between the rifling easy enough. Just use an old flash hider to test your threads. Start cutting your threads with the OD at .498 - .500

 

[CountryBoy19]

I would hope you have a dial indicator? At least?

He said he has 2 Dial test indicators, DTI > Dial indicator...

I cant afford a 1/2x28 thread fit guage if i threaded a piece from say .510 and cut it with the threading tool to .498 max diameter assuming i threaded correctly would that basically be a good test guage? (I dont have the mating pieces to check fit with very often so wanted a near perfect tool to fit against. )

The "dirty way" is to use a flash hider etc. The problem with that is most flash hiders are Class 2 threads, using a Class 2A thread (external) as a go or no-go gauge to check a male thread doesn't guarantee that it will fit any other device. To reliably ensure your threads are to spec get a set of thread measuring wires ($20) and use your mics to get the true pitch diameter. This way you can thread any spec and any size you want and you don't need a thread gauge for every size. Thread wires are pretty simple to use; the hardest part is holding 3 wires & the mics (especially hard if the part isn't held in a lathe/vice/etc) but watch a few youtube videos and you'll get it figured out. There is is a trick to it.

I measure EVERY barrel I thread with mics & wires because I don't want a barrel coming back. It's nearly impossible to pick back up on threads to take another .001" off the pitch to get it in spec, I'd much rather take the extra couple minutes to make darn sure it's right the first time.

 

[ruger1800]

Practice on some scrap steel.