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View Full Version : brownells crowning tool pissin me off


vicvic
October 29, 2006, 08:03 PM
no matter what i do the crown gets chatter marks on it. i cannot get a smooth surface. i ve tried going light, going heavy. what am i doing wrong?

badbob
October 29, 2006, 08:21 PM
Generally chatter is caused by too many RPM and too light a cut. Since you already have chatter marks, slow your speed WAY down until the marks clean up. Use cutting oil.

badbob

vicvic
October 29, 2006, 08:31 PM
does anyone have a pic of theyre brownells tool crowned barrel?

guncrank
October 29, 2006, 09:06 PM
Go slow and light pressure. Any chatter marks can be removed with a swiss file and polished out with sand paper.

vicvic
October 29, 2006, 09:16 PM
how deep is deep enough?

VaFisher
October 30, 2006, 08:21 AM
If you would put heavy ( Lots ) pressure and turn slow it will give you what you are looking for. Put a little oil on it when you do this. If you have chatter in it now it may take some doing to get rid of it depending on how deep it is now. Once chatter starts it hard to get rid of it so don't get to frustated just work with it until you get the results you are looking for.

saands
October 30, 2006, 10:27 AM
The tool that I got from brownells has a pilot on it ... RPM's :confused: :confused: Mine works great just turning it by hand!!!

Chatter is the result of exiting the workpiece at its resonant frequency. That frequency is a function of the mass (higher mass gives lower freq) and the stiffness (higher stiffness gives higher freq) of the workpiece. If you are getting chatter, and you MUST stick with the lathe, then you can either change the resonant freq of the workpiece (support it differently ... chuck it deeper in the chuck??) or change the forcing frequency (adjust the RPMs) ... make smallish corrections here ... +/- 10% ... if you double or half the RPM, you might just end up on a harmonic of the natural frequency. Chatter and I go WAAAAAY back, so I've learned some of this the really hard way ;)

Saands

dfaugh
October 30, 2006, 01:24 PM
I've used mine (w/ different pilots/calibers) on several guns.

To eliminate chatter --- USE CUTTING OIL
WD-40 works just fine, but there are also oils made just for this purpose (even gun oil works well).

I had the same problem, but since my dad was a machinist, I figured out right quick that the oil was inportant.

P.S. I've done all mine by hand...Don't trust a power tool to cut at an even speed. Tedious to do by hand, but better results.

vicvic
October 30, 2006, 04:49 PM
all of my attemps have been by hand. i have no access to a lathe. i didnt think you could put the brownells tool in a lathe. so i should push as hard as i can spinning it slowly?

Tom2
October 30, 2006, 05:49 PM
I got one with several pilots for rifles. Pretty much same results even with some cutting oil. Maybe we should call their tech line at Brownells and ask about it. Mostly I used it on milsurps to clean up the end of the rifling. Went a little deeper on an old Swede rifle but it had the screw on muzzle cap so it covered the uglies. They make a brass lapping tool that is the same angle of the cutter, and you are supposed to put grinding compound on that brass bit and polish out the rough spots, but that never worked very well for me either. So I stuck with just doing minimal cutting just enough to clean up the rifling at the end, and touched it up with cold blue. On a milsurp, who cares. But on a fine sporter, I might farm the work out. They used hand tool cutters like that to crown M1 carbines at arsenal, and maybe Rifles too. They look hand cut but I guess it works for them. Best crowning job would be on a lathe, but I have not had access to a lathe to do a neat job of it for some time. Good luck.

Unclenick
October 30, 2006, 06:26 PM
I had this problem. I solved it by getting one of the flexible shaft extensions for an electric screwdriver and tapping a rod for the cutter that I could chuck into one of those small 1/4" hex adapter chucks inserted into the flex adapter. It would run smoothly and not chatter at all in that rig, and would even clean up chatter marks I'd left by hand. I concluded part of the reason was it regulated applied pressure with its spring. The other is that, under pressure of taking a cut, the spring in the shaft winds up a little which causes it to scoot forward after the chip breaks. This causes the cutter to skip over the deep grooves of chatter marks, so it doesn't cut them any deeper, but rather only works on the high spots around it.

Nick

Harry Bonar
November 5, 2006, 04:03 PM
Dear Sir:
Cut some denim and put a small slit in it and slide the pilot through and the denim on the face of the cutters with oil (one or two thickneses) and turn slow - should work!
Harry B.