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Thread: Straight hole boring
08-15-2009, 06:50 AM #1
Straight hole boring
Let me start by saying yes I have all of the legal paper work for my form 1 silencer. That said, I am doing a mono core .22 silencer for my Ruger Mark III that was professionally threaded. My question is how do I bore a straight hole in my 1" round bar 303ss and have it be straight? I have an Enco 12X36 lathe and have been experimenting. Here are my issues. I start by chucking up a 12" bar and use the steady rest to get runout as close as possible. I use a center drill to start my hole then use a standard 1/4" cobalt bit to peck drill in as far as it will go. I then switched to a 12" cobalt 1/4" bit that I got from MSC to finish off my hole, I went about 9" so I would have enough to put between centers. Here's the problem: my hole walks. So when I switch to the 17/64" and ream, it is really off. So my fix is to over bore the last 2 inches of the core to keep from getting a baffle strike but in doing so I lose a good amount of suppression.
I know the obvious answer is gun drill but short of spending a lot of $$ on buying a used one or $200 I was quoted to do 2-12" pieces is there another solution? I plan on doing some other form 1's not just .22. Has anyone adapted a gun drill to be used in a lathe. What about spade drills? Any help or am I just
08-15-2009, 07:25 AM #2
Has anyone adapted a gun drill to be used in a lathe. What about spade drills? Any help or am I just
Yes they make gun drills for manual lathes, but you'll start out with about a grand in the setup. Then the drills, but they're not to bad. I've got a Sterling Gun Drill that is extremely accurate. For example a 1/2" hole 18" deep is no more than .005 out at the other end. You do need .0005 or less feed rate with some materials requiring .0001 per rev. I spin the workpiece around 1600 RPM with .0005 per rev. on 1045 steel. Stainless would be less feed I think.
Call Doug Holley at Sterling G D. Maybe he can help you out. 888 338 1049
08-15-2009, 07:27 AM #3
Try your hand at making your owngun drill. From the pics I have seen they have one cutting edge and one flute that runs lengthwise. Mill a 90* flute lengthwise on a suitable size piece of drill rod and braze a piece of carbide to the end, grind relief like a standard twist drill, sharpen and give it a try. An old carbide insert might work.
08-15-2009, 08:27 AM #4
Viktor Astakhov's website has a download "primer" on deep hole drilling. as the guys say, it's not just the drill, you also need about 1,000psi chlorinated cutting oil flush, and the capabilities to sharpen the drill if you chip the cutting edges.
If it is a one off, and you are doing it as a hobby, you could use a d bit, started in an accurately bored hole 3 diameters or more long, and gently pecked, it will give you a truer hole than a conventional twist drill but at the cost of time.
That said, the holes in the baffles of a parker hale .22 silencer are about .25 so you have plenty of clearence for run out in the middle of the tube, and it is easy enough to get the exterior true and clock it in to bore either end true for the connection to the barrel and a tight clearence on the end cap.
08-15-2009, 08:33 AM #5
Why not start with stock that already has a straight hole in it? Such as a 22 or 6mm barrel.
08-15-2009, 09:31 AM #6
Cheechako, that is so b****y obvious, I wish I'd thought of it
if there is a smith near by who does barrelling, he might have some offcuts of lovely stress relieved...
08-15-2009, 01:55 PM #7
You may want to try aluminum for weight. drill a piece of 1.25 then turn it between centers to make it concentric.
08-15-2009, 09:05 PM #8
Barrel liners would work also and they are readily available in many calibers .
08-16-2009, 05:23 AM #9
Cheechako probably has the best idea, but you don't have to spend a lot of money to gun drill on a lathe, buy a gun drill bit from ebay, there is always a pile of them on there cheep. Thread the hole in the chuck end to accept a 1/2-13 bolt thread tape it and plug the end. Drill a 1/4 inch hole in the side of the chuck end of the bit and braze in a 1/4" tube. Get a tool oiler from an air compressor filter set and put it line and then blow mist oil through your bit at about 80psi and drill away. It works quite well, just hold the bit in a regular 3/4" drill chuck in the tail stock.
Cost about 75.00 tops.
08-16-2009, 07:47 AM #10
08-17-2009, 03:08 AM #11
If it helps, the reason I want to use SS is that I can use a 50/50 mix of peroxide and vinegar to dissolve the lead that builds up on the core. So I really would like to stay with the 303 since it machines nice. I have considered the rifle blank option from the beginning, just thought it would save me $$ (I am a tight arse on some things) if I could diy. If a guy did get a bbl blank what grade SS would machine the best or better yet, what should I avoid. I guess I am a little out of my league here but I may keep trying until I can get the thing right. Keep kicking myself in the ass for not taking some machining classes when I was at auto school.
08-17-2009, 03:14 AM #12
Virtually all stainless barrels are made from 416 stainless, with a few exceptions of course.
How long are you needing and where in southern Indiana are you. I am in southern Illinois and might have a piece.
08-17-2009, 03:57 AM #13
The design I am wanting is 7-8" long. Since I am not a precision machinist and I do make mistakes galore 10" or so would be great. I am in Jasper. Thanks for any help
08-17-2009, 06:54 AM #14
There is no reason you should have to pay a penny for a chunk of used stainless barrel. Gunsmiths, both pros and ams, usually have pieces laying around the shop and would be happy to give you some for the price of postage. Old barrels are cut up and used to make a variety of shooting stuff, from muzzle brakes to loading dies.
What diameter do you need? If you can't find anything locally I can probably come up with a free one.
08-17-2009, 07:01 AM #15
Thanks for the offer. We have 0 gunsmiths in my area, closest one probably 60 miles away. If you can come up with some cutoffs I would gladly pay for them.
08-17-2009, 07:08 PM #16
I am doing the same thing. But I am using AL. I drilled a shorter piece, right at 7inches. I turned the piece between centers and then chucked it up in a 4 jaw and got it started with a very short bit and then drilled with a jobber length 1/4 inch bit to the hilt. I turned it around and trued it up and drilled the other side and they met in the middle. True.
I made the end caps out of steel but the tube and baffle are aluminum .
These are the parts. The baffle has not been milled yet. It will look like Swiss cheese Soon.
Here it is screwed on the 10/22
Good luck, have fun.
Last edited by crumpmd; 08-17-2009 at 07:10 PM. Reason: spellin
08-18-2009, 03:28 AM #17
Excellent work, can't wait to see the finished product.
08-18-2009, 05:48 PM #18
Not to be late in the game or anything, but why are you trying to drill/bore a piece of solid stock? 6061 AL or seamless SS tubing are both perfectly true enough to use for suppressor tubes as is. Simply true up both ends, thread, wa la...suppressor tube !
I'm a class II with a SOT and manufacture cans for a living. I can appreciate all the good ideas posted here but guys, they're way overkill.
For a .22 cal can, aluminum is the material of choice for most manufacturers, unless you want it full auto capable, or just prefer the ss option for cleaning. Another quickie, normally better actually, is to use good ole 4130 tubing. .065 wall for your .22 can. Then it can be parkerized, powder coated, blued, or whatever your finishing preference is. The center of the 4130 tube (where there's no threads can be turned down to a .040 wall and it will still out last you.
Hope this helps.
Most all of our "cans" have not been available to the public thus far, but we're now going to start selling to the general public using design technology that no one is currently using !!
Rick Our Muzzle brake webs site www.bp-tec.com
08-18-2009, 06:30 PM #19
08-18-2009, 06:43 PM #20
Sniper... you know your right. This has been a very long day and I probably had no biz squirtin like that. I'm laughin at myself now...I just read it quick and thought he was trying to bore the tube for a core.
I'll quietly sink into the night and use a can on myself.