Gunsmithing CNC Barrel Channel Inletting Question

[tstevens]

When inletting a barrel channel what do you guys prefer for an end mill size and configuration? I fear that the 3/4" 2fl ball mill I have is going to be hard on the top edges of the stock and chip out gelcoat. If I had the software, i'd think a 3/16 or 1/4 would be ideal where you could have it surface machine with a smaller step over. However, that would be a damn lot of lines to long hand and do the math on.
The barrel is a MTU contour, so straight lines on this one with no radii and the shank. I'm thinking I can rough it out pretty close and not have so much to sand and scrape to smooth it out.

Thanks guys.

 

[300sniper]

i thought i was the only one that hand writes programs these days,lol

 

[gregt]

I've used a 1/2" 3 flute ballnose cutter on a manners stock with no dramas, video below. That was using a pretty huge stepover roughing out the channel. You can get cutters with a reverse helix if you're worried about chipping the gelcoat, they push the chips down instead.

None - YouTube

 

[MikeeBooshay]

I use a 1 1/4" or 1 1/2" ball router bit - they are ten bucks! Use the smallest bit that your barrel needs at the muzzle end of the stock and figure your step overs/ups/downs from there. Spin it at warp speed ( 2000 + ) for best finish. I assume you are doing this on a Bridgeport, hence the question?

This was done with that bit, then a small 4 flute to make the pockets for the action.:

 

[LRI]

A 3/16 3F em is what I use for finish work on a channel. I start w/a 3/4 lollypop and leave .1 for the little guy. We run a .035 stepover in composites and .01 with wood. Climb cut, start inside and work out in a ccw direction and you'll be in good shape.

Avoid coated carbide. Thr resins have a tendency to try and bond to the tool. Uncoated works better as the resin buildup induces thermal shock and wears out the tool prematuraly.

Good luck.

C.