dovetail cutter

[balibalistic]

Hey guy's,

Quick question regarding dovetail cutters: what kind of speeds should i be running them at? i'm using them to dovetail in 6al4v titanium. i baught a couple cobalt cutters which are 3/4". i ran my mill very slow 200 rpm because any faster just did'nt feel right. but i wore both out very fast.

Any reccomendations of which to buy and how to run them??

 

[Nathan the Machinist]

I have found that carbide doesn't last much longer in this application, and 200 RPM sounds okay for 3/4" in titanium. The only thing I can think to recommend is be sure to feed hard enough and keep it cool and don't try to take it all off in one pass.

A 3/4" cutter in titanium should be fed at least .003" per flute, and preferably more. Otherwise the titanium (which is strong, but flexible) will move, but not cut - leading to high cutter wear. Also, titanium conducts heat poorly, and the shape of a dovetail cutter is such that the tips can get overheated easily. If so, use flood coolant.

 

[David Wesner]

Were you just milling an "undercut" on one edge of a bolster or were you trying to create an actual dovetail ? The reason I ask is that if the latter is the case (a dovetail), standard procedure is to first buzz an endmill through. I use the dovetail cutter to remove only the undercut area of the dovetails geometry.
Your RPM sounds ok. When I'm running one in Ti or SS I can almost count the flutes as the tool spins .............. almost, but not quite
So much of the machining I do now is done intuitively, including speeds & feeds,.......... gauged only by the experience I've acquired over the last 30 years. Sorry I can't be of more help

If you want formulas, code or high tech-"state of art"-"cutting edge" advice & help, Nathan the Machinist is THE MAN :thumbup: :thumbup:

Edited to add : See ............. at my age I even type too slow. Nathan beat me to the punch

 

[balibalistic]

Ok, thank you guys!!

Yes, i'm only doing an undercut of the bolster area's. i remove the bulk of the TI with either a 1/2" or 3/4" endmill. i was using cobalt but they dont last long in the TI so i just picked up a carbide hanita to try out. so i should probably just use standard HSS dovetail cutters with slow speeds?? where do you guys buy your dovetail cutters?

 

[Nathan the Machinist]

In an industrial mill that weighs four tons, and with engineered speed, feed and DOC, the carbide will outlast the HSS 5:1 and increase productivity. But in a home shop they're probably going to give similar service, and the HSS costs a lot less.

You got a 3/4" carbide Hanita? That is good quality industrial production tooling. What did that set you back?

I buy tooling at a lot of different places, but one that you would have heard of is MSC. My shop has a 30% discount there, but they frequently give that discount (or better) as a "daily special" if you look at the site in the mornings.

Perhaps a dumb comment, but..

If you're milling the undercut for your bolster - why not simply hold the loose bolster at an angle and mill it with a standard end mill? I must be missing something

 

[balibalistic]

Nathan, the Hanita is only a 1/2". i got it off e-bay for $16

I machine the whole handle.., i start with 3/16 TI and machine out approx 1/8 in several passes. i was using cobalt roughing endmills and they were burnt out after machining maybe 6 handles. so i figure carbide gotta last a bit longer?