Re: removing fluting tool marks?
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bohem</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 300sniper</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bohem</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 300sniper</div><div class="ubbcode-body">
i'm no machinist, just a garage hack but i think that is chatter marks left by a convex cutter, not ball end mill. i have fluted barrels with a ball end mill and ramped in and out of the cut with no marks like that. the first one i did had a slightly rough finish on the sides due to insufficient flood coolant evacuating chips and getting re-cut. </div></div>
Did you use a roughing reamer when you ramped in and out of the cut? The serrated looking flutes look like what did it.
Granted that picture is a standard REM not a ball, but you get the idea. </div></div>
i didn't bother using a roughing endmill to flute barrels and i don't think i will be using an endmill anymore period. i think a convex cutter on the side of the barrel (if i had a horizontal mill, it would be on the top) is a better way to go about it. you will get better chip evacuation with a convex cutter and you will get a better finish. a full cutter width groove with an endmill doesn't leave the best finish on the walls. most real machinists (again, i'm not one) will also argue that a ball mill has a "zero feed rate" at the very center. i agree with that in theory but in practice, i have found it to be at least partially not true.
by looking at that picture, if they did use a ball endmill they ramped it in and out of the cut. there is no way a roughing endmill would leave those marks. in my opinion, there is no way a ball endmill would leave those marks either as it is ramping in our out of the cut. </div></div>
I don't think they ramped it in/out of the thing, I think they used a terraced roughing pass profile, then finished it with a BEM and didn't run the finish the right depth.
I agree, the best way to do this on a vertical mill is a convex cutter down the size with a flood coolant washing it away.
Bottom line on the whole deal is I don't think after shelling out the kind of money that a 50 cal barrel costs, the OP should be dealing with this issue from a top line custom barrel maker. No questions about it.
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if they ran a terraced roughing profile they would have had to ramp in and out the finish profile. they would have also had to ramp or plunge into the roughing cuts somewhere. ramping it in at the end would make the most sense, even on the roughing pass. the marks just don't look like they were from a bem to me. definatly not a square em because there would be a flat bottom of the groove.
