Gunsmithing Puttin wrinkles on the bolt. . .

[LRI]

Just thought if anyone was curious as to how helical fluting is done on a bolt, I'd take the opportunity to show one way of doing it.

This is a L/H Remmy, hence the "backwards" flutes.

The tool I use is a bit different than most. It's actually a chamfer tool, but works pretty dern good for this stuff too. I like this tool because I can get a deep wide gullet. Since the only purpose for doing this is to look cool and give the funk someplace to go I figure "go bold". The other reason is surface speed on the cutter. No matter how fast you spin a ball endmill the center of the tool is essentially motionless and this means it's not cutting so much as it is "bubble gummin" its way through the material.

Most are probably used to seeing the flutes reach further up under the receiver ring. I prefer to come a bit short as I think its better to keep as much bearing surface contact as you can behind the receiver and bolt lugs. Might be over thinking it a bit, but its not hurtin anything so I run it this way.

The key to this stuff is RIGID SETUP and a high quality cutting fluid/coolant. The part (the bolt) loooooves to chatter if you give it half a chance. It sounds like a router on crack when its running.

Enjoy.

Chad

 

[300sniper]

Re: Puttin wrinkles on the bolt. . .

i've had good luck slotting with ball mills even though i am apparently not supposed to. all the <span style="font-style: italic">real</span> machinists i know talk about the center of a ball mill having a "zero" feed rate due to the zero radial depth of cut. the way i see it, at the same time it actually gets to zero radial doc, you are at a zero axial doc.

the cutter you are using leaves a nice shape for flutes. i am sure you can feed faster and get the swarf out of the way better with that setup than with a ball mill also.

 

[LRI]

Re: Puttin wrinkles on the bolt. . .

Cool!

I still wanna know your secret then cuz half the time when I use a ball to whittle a gullet or channel it ends up lookin like chit in the middle. I typically end up just making a dead pass or two to get rid of it.

Either ways, if it's werkin, don't "fix" it.

C

 

[300sniper]

Re: Puttin wrinkles on the bolt. . .

me being just a hobbyist, i have time on my side. i'm probably quite a bit more conservative on my feeds and depth of cuts.

 

[Choeppner99]

Re: Puttin wrinkles on the bolt. . .

I really like the spacing and depth you did on those. When I get mine done eventually, I want something like that.

-Chris

 

[Cinch]

Re: Puttin wrinkles on the bolt. . .

Looks good, Chad! I'm gonna have to come see you again. And bring a few bolts with me.

 

[DAVETOOLEY]

Re: Puttin wrinkles on the bolt. . .

Chad

Looks great. You're 10 times the machinist I'll ever be. I wonder about the rigidity of the tool not the work in this setup.
Got a question/suggestion when using a ball end mill. I don't use one very often, mostly inletting stocks. If using one on a vertical mill why wouldn't rotating the head say 5 degrees right or left, towards the direction of feed help? That would hide the tip behind and above the cutting surface eliminating the dead zone.

 

[LRI]

Re: Puttin wrinkles on the bolt. . .

Dave,

Regarding the tool. It's actually intended for deep hole chamfering, thread milling, grooving, etc.

I'm guessing the shank is solid carbide. Whatever it is it weighs a bunch, more than some of my endmills that are bigger/longer. So I'm not really sure what it's made out of. It uses a separate insert that's replaceable. Little bastage cost almost $600.00!

I ordered it long thinking I'd need the stand off from the CAT40 tool holder in order to clear the bolt handle. In practice it could be quite a bit shorter. I may order another one a bit shorter and just keep this for other jobs. I have to say that I'm quite pleased with the surface finish it delivers. No chatter or burrs anywhere, even on the entry into the stock.

I hadn't fluted a bolt in a long time so I turned a stick of 4140HT to .700 and proofed out my program on that. Just an easy way to verify the code and speeds/feeds. Then I went for it.

Regarding the ball. My main reason for not using one is mostly because I like the geometry of this tool better. It's just different looking than the norm. I do quite a bit of surfacing work and there a ball is often the only option. When in conjunction with a 4th axis I do offset the tool to take advantage of the shear/surface speed on the side of the cutter whenever possible. It's only when I need to make a direct square/inline plunge/groove that I have issues with the surface finish. This is often with tool steels as I don't machine much from aluminum. Most the time if I have the room I'll hog out a roughing pass using a conventional endmill and then come back for a finish cycle.

I have CNC machines and the masts are rigid. They move in the Z axis only. Rotating the head isn't an option for me unfortunately.

When I inlet stocks I drive all my tool paths as surface models. Here is where the ball endmill really shines. It's taken me a long time but I've been able to figure out a process for modeling the exact receiver profile (even the tang!) so that I have a uniform film of bedding from one end of the action to the other. The idea being that since all epoxies shrink to some degree during curing I can at least ensure the shrinkage is uniform from one end of the bedding job to the other. Might be overkill but it doesn't seem to hurt anything. The ol fashioned indicator test typically gives me results at or under .0005". Usually the front screw will yield around .0003 to .0005 and middle/rear won't move at all.

Anyways, it seems to be werkin pretty good.

 

[T J]

Re: Puttin wrinkles on the bolt. . .

Looks great Chad, thanks for posting that... first time i've had a rifle on a forum. Look forward to putting that girl to work this hunting season!

 

[x ring accuracy]

Re: Puttin wrinkles on the bolt. . .

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 300sniper</div><div class="ubbcode-body">me being just a hobbyist, i have time on my side. i'm probably quite a bit more conservative on my feeds and depth of cuts. </div></div>
Hobbiest my ass, you know more than most.........PERIOD!