22LR chamber work Boring bar!

[skeetlee]

I am pretty close to convincing myself that in order to cut the very best possible 22LR chamber one must use a boring bar. Dont get me wrong here. I have cut some pretty amazing shooting barrels with reamers. several in fact. Reamers work well! The issue with a reamer is tool marks, and the process one must use to deal with the tooling marks. takes a lot of time to deal with the tooling marks properly.
I need to find a few tools before i start practicing with the boring bar and i may need a little help setting up my compound. I think i need a protractor that reads in minutes? I also need a boring bar thats capable of doing what i need it to do. little but ridged.. I know those two things dont go together real well, but there has to be a tool out there. I know some of the cnc guys use boring bars to cut their rimfire chambers, so this is absolutely doable. I just need some advise on first, what protractor i should purchase and then what boring bar, I was hoping someone here might have some info? Im all ears if so, please! Thanks a bunch Lee

 

[Alan Warner]

Work your compound slide till it moves without flaw.
May need scraping etc.
Next, build a sine bar system into your compound swivel for exact and repeatable angular settings.

 

[Dusty Stevens]

I have a carbide bar with indexable bits. It may be a micro100. Whatever it is it should be rigid enough over steel

 

[El Matador]

You can set up your compound with nothing but a good indicator and possibly a piece of drill rod. Check out the video by Joe Pie on cutting precision angles. He uses the tailstock quill as a baseline but if yours isn't perfectly straight you can indicate a drill rod or just turn a straight section on any piece of stock. Then use the indicator along with your cross slide dial and compound dial to make sure you have the correct angle.

 

[Walt Krafft]

Kennametal makes small enough bars. Get solid carbide bar with positive rake inserts.

 

[tac284]

Might look into ph Horn supermini and mini. I would go for the sine bar method like Alan said.

 

[Dusty Stevens]

I cant imagine a boring bar turning a better finished or more accurate chamber than a reamer.

 

[linekin]

Lee, you may have already seen this but Stiller talks a little about what he uses in the thread.
http://www.rimfireaccuracy.com/Forums/showthread.php/11510-Barrel-chambering?highlight=boring
Initially when I wanted to start doing my own chambers I wanted to bore them. I used Micro 100 bars & while the finish inside was decent I was never able to take a cleaning pass without f-ing it up.
Thats when I switched to reamers & the holder I sent you to try a few years ago.
I'm happier with the results from my reamer.

Keith

 

[Will Henry]

I have never seen any significant toolmarks in a 22LR chamber from the reamer. I have bored a lot of small holes (in hydraulic valve bodies) and if I wanted a good finish, honing was a required part of the operation. The best way to produce an accurate hole, with multiple diameters and smooth transitions, in hydraulic valve bodies, turned out to be to use a reamer. Go figure. WH

 

[Roeder]

My simple way to get a close angle on the compound is to just make 2 marks on the side of the compound and set my indicator so I can move the apron while sweeping the side of the compound from mark to mark. About .070 for a 2o angle is pretty close.
I know of at least one top rimfire smith that does chambers with a boring bar and a manual lathe and a couple that use a CNC. I tried it and was able to make a serviceable chamber but I would need to practice a lot to feel like I could get it right without going oversize every time. So I ordered a spiral flute reamer and have been pretty happy with the results. If I get to where I have a CNC lathe available I'll probably never ream a rimfire chamber again.

 

[Kookie]

Lee, there is a lot of good info on pages 2&3 of this thread on rimfireaccuracy.com.
http://www.rimfireaccuracy.com/Foru...-reamer-for-new-build/page2?highlight=Reamers

 

[skeetlee]

thank you gentlemen most people who use reamers for 22lr chambers have no idea there are tool marks. You have to polish to see them. once you do this you will never sleep sound again.. LOL the lapping compound really brings the tool marks to life. a 22 cant hardly shoot a burr or smooth out a spot from a reamer that might not have been 100% all your top rimfire smith lap their chambers for this very reason. I know there are fellas using boring bars to cut these chambers and that just makes more sense to me. the skill set involved in doing so is gonna be the issue. If i decide to go this route ill have to practice a crap load. As far as bars go i just cant imagine a boring bar small enough yet ridged enough not to sing a song while cutting I guess i just haven't used such a tool yet to know? kennametal is my preferred choice in tooling, so ill take a look

 

[ridgeway]

Quite a few small carbide shanked boring bars out there. I got a grizzly that will fit inside a .236 bore. There are smaller ones out there widia, circle, micro 100. Make sure shank is carbide.

Have you tried reaming with an oil muzzle flush. If the reamer is finely ground, hard to believe you will have issues with tool marks.

 

[skeetlee]

chuck
you would be surprised at the tool marks. Once you start the polish they pop out like a sore thumb The idea is to just lay any possible problem down so its not a problem At least in my mind. Lee

 

[Tucker65]

Are you using HSS reamers or are they solid carbide. I would think with a solid carbide reamer and rigid lathe you'd be able to get a really nice finish, especially with the surface speed you're able to run with carbide.

 

[skeetlee]

I’ve given the carbide Reamers some pretty serious though. I’ve had a couple conversations over the last couple days that pretty much has me convinced. I am also gonna play around with how I hold the Reamers as well. I’m thinking a floating holder isn’t the best idea here. A dialed in tailstock with a running true chuck might be the better idea. After all we are only cutting a tad over half an inch. So carbide with a ridged reamer hold/ feed might be the trick? I’ll soon find out.

 

[tobnpr]

I don't know a damn thing about rimfire chambers...never cut a single one.

But the mere idea, of trying to hold one tenth, with any boring bar, seems crazy to me on a manual machine even with an accurate DRO for either chamber length or diameter. I sure as hell couldn't do it, nor do I know anyone that could.

Then, how could you possibly measure the chamber to that level of accuracy?

Pipe dream.

 

[STS]

Boring a rimfire chamber is like treating the symptom rather than treating the disease. Examine your reamer under magnification and you'll clearly see where the tooling marks come from in the leade. Get the reamer REALLY sharp and there's no need for a boring bar.

 

[Will Henry]

Finding a chuck which will hole the reamer co-axial with the machine would be the challenge. A modified tailstock which would hold the reamer in a collet would have a chance. I just cut a new chamber on my Model 52 and, try as I might, I couldn't see any toolmarks or any need for polishing; this looking with the old Hawkeye scope. I held the reamer on the tailstock center as I usually do. WH

 

[skeetlee]

Will
I will guarantee you if you were to polish that chamber of yours the tool marks will pop right out at out. Try it on a stub if you don’t think so. I didn’t see any tool marks either but I trusted my Counsil and did as he suggested. After all Jerry has built national winners so I listen.
All my barrels are shooting really well but I’m always looking for a better way!!