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What's the best way to inlet a barrel channel in the mill?

NewGunPlumber

Aluminum
Joined
Dec 18, 2019
As the title suggests how are you guys going about setting up and milling barrel channels for profiled barrels?

The barrel is essentially conical so the channel needs tapered sides and bottom.

And photos of setup or how you indicate centre and start of taper would be appreciated!
 
What Clarkmag said will get you approximately there. Radius will not be perfect. I wrapped the old barrel with one layer of 240 wet or dry paper and sanded till I do the fit I needed. No idea how a gunsmith that knows what he is doing would go about it. But it got me to a satisfactory end the one time I did it.

On any barrel the wet or dry paper will cut to a larger radius than the barrel. Just work with a smaller part of the tapered barrel on any given spot.
 
In the latest issue of Machinist's Workshop there was an article on making and using a pantograph attachment for Bridgeport type mills. Basically a plate that clamps to the quill and has an interchangeable stylus a fixed distance from the spindle centerline.

He used this setup to profile the underside of an express sight to fit a tapered octagonal barrel and I don't see why this idea wouldn't work for inletting a stock as well.

The fixture had 2 V-blocks mounted precisely parallel to the work piece to hold the barrel while casting a pattern. He made the pattern using epoxy after coating the barrel with release agent. Very similar to glass bedding except to an aluminum rough pattern.

There would still be hand work but especially with round barrels a rig like that would get pretty close.
 
Clarkmag are you taking a cut the adjusting the angle of the vice to get the correct taper.

Scott. Interesting idea. Sounds a bit time consuming but could be a good trick to have up the sleeve
 
I don't mean to be negative, and indeed I would like to be constructive.
But why?
First of all, the barrels are not conical, and a machine process is likely to be far more labor intensive than the traditional methods.
Make some inletting screws, make some inletting black, use scrapers and rasps to bring the barrel channel into shape. Paint the metal and mark the high spots on the wood. Wrap your deep well sockets with fine sand paper, and take off the contact points. Glass bed and check for free float clearance.
I am troubled by so many posts that don't give full details of what one wants and why.
What rifle and barrel are you asking about?
Do you just want to finish a custom project, or are you trying to create a process for production?
It is hard to help if I don't know what you are doing.
 
Clarkmag are you taking a cut the adjusting the angle of the vice to get the correct taper.
No. I fiddle with all 3 axis as I go along.

My Rockwell 21-100 mill is gone. I now have Bridgeport with 3 axis DRO and a 4th on the quill.

I only build a couple rifles a year and shoot a couple deer a year.
 
If barrels weren't conical then why would you even bother using hand tools? Just plough a ball mill of the appropriate size down the forend and call it done hey?

Tapered / conical whatever you like to call it the majority of barrels are a different size at one end to the other.

What I'm asking is "is there a better process to inlet barrels into stocks that is more uniform, consistent and quicker that doing the job by hand as you have described above?"

This applies to solid timber, laminate and synthetic stock of barrel profiles from 1.25" parallel (simple) down to a no3. This is not for production but my time is valuable and I like doing things in an efficient way that can be accurate and repeatable and that's what I thought this site was about.
 
No. I fiddle with all 3 axis as I go along.

My Rockwell 21-100 mill is gone. I now have Bridgeport with 3 axis DRO and a 4th on the quill.

I only build a couple rifles a year and shoot a couple deer a year.

Ok makes sense. Do you mark a line to give yourself something to visibly follow or have a few measurements worked out and wind into those at various points along the way?
 
...

What I'm asking is "is there a better process to inlet barrels into stocks that is more uniform, consistent and quicker that doing the job by hand as you have described above?"

This applies to solid timber, laminate and synthetic stock of barrel profiles from 1.25" parallel (simple) down to a no3. This is not for production but my time is valuable and I like doing things in an efficient way that can be accurate and repeatable and that's what I thought this site was about.

What you're saying about time, applies to the time spent in setting up the job as well: in most of the one off jobs, "slow" manual methods at the end of the day are faster, more reliable, and less error-prone than setting up a job on a machine.

Perhaps, if you have a CNC wood cutting router with enough Z travel/room to accommodate the stock, and you are good in pulling out something at the first trial, using it to inlet the stock could be your most efficient option...
but, again, be objective in evaluating the time spent in writing the code and testing, before you feel confident enough to run it on your stock with minimal risk of scrapping it.

Paolo
 
REGUARDS TO YOUR RESPONSE: What I'm asking is "is there a better process to inlet barrels into stocks that is more uniform, consistent and quicker that doing the job by hand as you have described above?"

The answer is no. At least no one, after 500 years, has found a better way to do things. This is why a true craftsman can command a high price for his labors.

Not all barrels are conical. In fact few are. Many have a cylindrical portion around the chamber area, a conical length on the muzzle end and a transition (Swoop) in between that could be either conical or radiused.

Assuming you were a rifle maker, you would have two choices. One is to use a vertical mill with a small cutter programmed to remove wood as required much as a pantograph does. The other choice is to make a solid cutter in the profile of the barrel and use it on a horizontal mill.

But to use ball cutter, would require a change of cutter every small length of the barrel channel. You have to consider both the width of cut and the depth.

I understand this may not be the answer you want, but I appreciate your inquiry. And if someone else has a better solution... I'm here to learn.

maddcoprofile_zps1a123b3d.jpg
 
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Unless your barrel is perfectly straight from the action to the muzzle a manual mill is not the way to do it. CNC mill yes, do you have a solid model of the barrel receiver and stock? If you don't buy a few gouges and a round scraper. I have all technologies available and chose to use chisel's and do it by hand. One can easily achieve a .005" gap along the barrel on your first try. The gouges and scrapers were less than $100.
 
What I'm asking is "is there a better process to inlet barrels into stocks that is more uniform, consistent and quicker that doing the job by hand as you have described above?"

This applies to solid timber, laminate and synthetic stock of barrel profiles from 1.25" parallel (simple) down to a no3. This is not for production but my time is valuable and I like doing things in an efficient way that can be accurate and repeatable and that's what I thought this site was about.

OK, as a guy who used to think that this could be automated to a large extent, but learned the hard way, here's a quick answer:

No.

Now, here's an explanation in three parts:

1. Good stock wood, especially maple or high-figure walnuts, will chip out if you come at them with a end mill (or ball mill) and think you're going to just run the mill up the side of the barrel channel. You can get a clean cut in low-figure walnuts (in my experience), but once you start paying $600 and up for a stock blank, and you start getting some nice figure in there, look out. If you do run a mill up the barrel channel, the safest bet is to just use it to rough out the barrel channel and leave anywhere from 0.050" to 0.125" on the sides of the channel to be cut off with hand tools.

Laminate wood stocks sometimes cut better.

Oh, and woods are abrasive, and will eat up HSS tooling. Use a good quality carbide ball mill.

2. Barrels only become true along their length with a bunch of work. Most people don't realize this, because they don't have well-developed eyes to judge these things. I cannot recount how many barrels for which I've paid extra money for the barrel manufacture to profile them that show up with dips, high spots and waves in the exterior profile of the barrel. If you are going to use these barrels as supplied, you will quickly find out that a barrel channel cut with a machine doesn't quiiiiiiite fit, or it leaves gaps. Not huge gaps, but gaps nonetheless, that aren't indicative of the highest quality work. When your customer is supplying you with a $600 to $1200 piece of walnut, they want perfection, not "close enough."

I have had to true up some barrels that were as much as 0.020 out of round with the bore. Some barrel outfits (I won't mention who) put some very junior employees on the job of polishing barrels on the belt grinder with the barrel spinner, and you sometimes get very junior-level results. I've had to take light finish cuts on a lathe and then strike some barrels for hours with a lathe bastard file, draw-filing it, to get it round and smooth again after someone who didn't know what they were doing "polished" it on a belt grinder.

3. A large part of your question is probably predicated upon you not having seen top-quality gun work. Most people have not. Modern mass manufacturing of guns has turned "free floated barrels" into an excuse to ship rifles with so much room between the stock and the barrel, you could fit a wad of currency around the barrel and run it up/down the length.

Last issue, which I forgot to mention:

I've used a mill to rough out barrel channels and receiver inlets. But I've only ever done that with a piece of wood that wasn't a rough-cut stock. I've done this only when I've had a pure slab of wood, with flat sides.

Most of what newbies don't understand about gunsmithing comes down to this: Gunsmithing looks easy on paper. Oh, you want to make XYZ? Put it on a five-axis CNC mill with the right software, and ta-da! Instant gun parts, made nice and cheap.

Well, that's a nice theory. I used to subscribe to this theory. Then I went to gunsmithing school, and started working on actual guns.

Here's what most people don't understand about using a machine tool (mill or lathe): You need to set up the part, and hold it, in a way that you can work on it, and you need to be able to indicate it in.

Sounds real obvious, right? OK, so let's talk about cutting the barrel channel on a stock blank and you don't have a truly flat slab of wood, or on a stock blank that doesn't have a flat side any more - because it's been rough duplicated.

When I mill a rough barrel channel with a carbide ball mill into a slab stock blank, I will use my Saf-T-Planer to mill at least one side of the stock blank (depending on how thick the blank is) to be as flat as I can make it, and after that, I'll put the stock blank into a joiner and make the top edge be as perpendicular as I can make it to the newly-flattened side. THEN I can put this into the vises on a mill and make a rough cut.
 
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