Gunsmithing Contouring from a blank

[lw8]

Most smiths seem to prefer barrels that are contoured from the maker. From what I understand, contouring a blank isn't super hard and it seems like the smith would have more control over the final finish, dimensions, etc by contouring himself.

Why is this not more common?

Is there a downside?

 

[Mark Housel]

Re: Contouring from a blank

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: lw8</div><div class="ubbcode-body">Most smiths seem to prefer barrels that are contoured from the maker. From what I understand, contouring a blank isn't super hard and it seems like the smith would have more control over the final finish, dimensions, etc by contouring himself.

Why is this not more common?

<span style="font-weight: bold">Is there a downside?</span> </div></div>
The downside is mostly the additional labor and cost that that imposes I imagine.
Yes you have greater control at the expense of the hours needed to profile.
The makers have big CNC lathes that crank these things out in no time.

For me, just looking at a small drawing and some numbers doesn't give me any <span style="font-weight: bold">feel for, or real understanding</span> of that the barrel actually looks like.

The projects I've completed so far sort of required that I profile a barrel anyway.
One to fit an existing barrel channel (wood stock already inlet and bedded), a barrel for my custom 10-22 action, the duplication of a barrel for a savage 99, in an other caliber, etc.

Not having a tracing lathe or billion dollar CNC shop didn't help me in the time department either.

 

[yote_slayer31]

Re: Contouring from a blank

Lathe set up and time to profile a barrel it would be cheeper to buy 2 Name brand premium barrels.

 

[sinarms]

Re: Contouring from a blank

It is a P.I.A. if you are doing it on a manual lathe with no taper attachment. I have done it. Will I do it again? probably on my own only. I'll gladly pay Brux to contour my barrels for me.

 

[Mark Housel]

Re: Contouring from a blank

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sinarms</div><div class="ubbcode-body"><span style="font-weight: bold">It is a P.I.A. if you are doing it on a manual lathe with no taper attachment.</span> I have done it. Will I do it again? probably on my own only. I'll gladly pay Brux to contour my barrels for me. </div></div>

Yeah, yeah, that's what I meant to say.

 

[customshooter]

Re: Contouring from a blank

i contour barrels...but it is a pain in the ass... the cutter will skip around alll over when you get about 1/3 from either end using a dead center just cut in the chuck, a dog, and a live center at the end. i use leather gloves and support the back of the barrel during cutting...and only do this if i have to....ick...

 

[gszeto99]

Re: Contouring from a blank

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: customshooter</div><div class="ubbcode-body">i contour barrels...but it is a pain in the ass... the cutter will skip around alll over when you get about 1/3 from either end using a dead center just cut in the chuck, a dog, and a live center at the end. <span style="font-weight: bold"> i use leather gloves and support the back of the barrel during cutting</span>...and only do this if i have to....ick... </div></div>


That sounds dangerous....be careful with your hands.

 

[Mark Housel]

Re: Contouring from a blank

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: customshooter</div><div class="ubbcode-body">i contour barrels...but it is a pain in the ass... <span style="font-weight: bold">the cutter will skip around alll over when you get about 1/3 from either end using a dead center</span> just cut in the chuck, a dog, and a live center at the end. i use leather gloves and support the back of the barrel during cutting...and only do this if i have to....ick... </div></div>
Sounds like your tool is set too low maybe?

I bulk off most of the material in the chuck and a live center and set 1" steps for my taper at maybe .050 oversize.
I cut .050 to .100 long steps for the "swoop" up to the cylinder.

This way I'm always cutting as close to the chuck as I can before going between centers.

Leaving things oversize takes care of any non-concentricity between the bore and the outside when I go between centers and cut to size.

Then I offset the tailstock for tapering cuts between centers. I do as little as I can get away with between centers as this is the least stable configuration and the most chatter prone.

Finish up the swoop with a file, then spin it.

Seems to work OK for me without what you are describing although there are most always better ways that I haven't learned yet.

It <span style="font-weight: bold">is</span> difficult to remove chatter once it is there, but this process and keeping the tool high seems to prevent it from starting.
One guy in class bent his barrel badly from chatter and leaning on it with something to try to minimize the chatter.

 

[bohem]

Re: Contouring from a blank

A follower rest is an extremely cheap solution to keeping your hands away from that rotating barrel and cutter ESPECIALLY with leather gloves on.

I've seen what happens when those kinds of things go wrong, using hands as a support and wrapping them up in a material that can bind is very dangerous.

 

[Mark Housel]

Re: Contouring from a blank

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bohem</div><div class="ubbcode-body">A follower rest is an extremely cheap solution to keeping your hands away from that rotating barrel and cutter ESPECIALLY with leather gloves on.

I've seen what happens when those kinds of things go wrong, using hands as a support and wrapping them up in a material that can bind is very dangerous. </div></div>

A follow rest only works for parallel turning.

For tapering it would require something different that could follow the contour of the barrel.
I've seen an air powered device that kept pressure on the part opposite the tool but it was pretty bulky and complex to get set up.

 

[STR]

Re: Contouring from a blank

Guys, it's too inexpensive to send a barrel back to a manufacturer to have it profiled to your specs, to risk messing it up in your shop which may not be properly equipped to do so. Not to mention again the risk of getting caught up in rotating equipment that won't even know you're there. You want to see what that's like, just google lathe accidents and click on images. That will make you keep your hands where they belong, off the work. As mentioned above, the follow rest is the way to go if you feel you must try this task on your manual lathe, plus a taper attachment. Just don't want to see or hear about any of my brothers getting hurt or killed on a lathe. Good luck.

 

[Brutas]

Re: Contouring from a blank

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: STR</div><div class="ubbcode-body">Guys, it's too inexpensive to send a barrel back to a manufacturer to have it profiled to your specs </div></div>

We will re-contour on of OUR barrels usually for $40 plus return S&H. Usually in 2-3 weeks.

We designed and built our following steady rest for our CNC lathes. But for 600 barrels a month whats a couple grand!

 

[STR]

Re: Contouring from a blank

Guys, Brian just did one for one of my customers and it's just perfect. Thank you Brian for the work and your comment on the matter.

 

[colchester]

Re: Contouring from a blank

I can cut about 15" in length with my lathes taper att. Until recently I would have avoided turning a barrel on my lathe. I saw antoher guy turn a barrel with ease and asked him how he did it. He used a HS steel tool ground with positive rake, he turned the barrel about 120 rpm and fed the tool fairly quickly. Taking light cuts the barrel remained cool to the touch and the finish resembled a very fine shallow thread. I tried it out on a old blank cut it along the entire length in 2 passes breach end held in a chuck live center in the muzzle end, no follow or steady were used. I was amazed it cut without chatter

 

[Country]

Re: Contouring from a blank

Tool angle into the cut is also important. If the leading edge is more towards square across the work then the cutting pressure is more towards the chuck and less towards the back of the lathe so less deflection of the barrel.

 

[msalm]

Re: Contouring from a blank

I've contoured a couple barrels for my own use, and it is a PITA, not to mention if it is a button rifled barrel it will likely need to be lapped afterwards. The button is pulled through a full-sized blank, contoured and THEN lapped as the muzzle dimensions get a tad larger when the metal is removed for a smaller profiled barrel. It must be lapped out at the breech end to open up the bore so the muzzle is the same or preferrably tighter in bore dia. I'd rather leave that up to the barrelmaker. That said, the first barrel I ever worked on was an un-turned Shilen select match 7mm I chambered for 280 Ackley Improved. I wanted to 'do it all' for the experience. That was a good shooting SOB after I was done turning it down to about a #4 sporter contour finished at 26" even with my inexperience. I've since switched to mostly cut-rifled tubes and they're a little more forgiving if they need a diet but I still let the maker do it.