upside-down dovetail cutter? is there such a thing?

[akula169]

I need to cut some slots that are essentially upside-down dovetails (the top width is .50" and the bottom of the channel is .25").

Is there anything out there like that? I've been searching all over the place and can't figure out how I'd cut such a slot or if I could find a cutter like that - or, as a last resort: how I'd even go about making one).

???

[jcurrell]

There are angled end mills that start at 1 or 2 degees and go on from there for mold clearance angle. I have 45 degee chanfering mills something inbeteen .

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[ERBenoit]

Chamfering mills would probably work. You will have to mill the .250" wide slot first, regardless of what cutter you use. You could try "mill-drills", an endmill with a 90* included angle. Mill your .250" wide slot, then using the mill-drill chamfer the sides of the slot. They will produce a 45* angle.

[akula169]

Ah yes, thanks for the answers.

Did I mention that I love this forum?

[Allan Waterfall]

Is it possible to mount it on an adjustable angle plate after cutting the .25" slot first?

Allan

[akula169]

Not sure... I'm trying to replicate a part that looks like this:

http://www.inoperative.net/vanes.jpg

So, the cut has to be repeatable accurately.

I have a rotary table, but am having a hard time figuring out how to hold the piece. If I center it in a chuck, the mill does not have enough clearance to get to the part.

[Paul Alciatore]

They are called single angle chamfering cutters. Here's one, they have about 88 different types/sizes.

http://www1.mscdirect.com/CGI/NNSRIT...PMPXNO=1709181

Paul A.

[akula169]

More info:

the bottom angle of the channel needs to be 131 degrees, and I'm sure that finding a 82 degree mill/drill bit isn't going to be easy

45 degrees is just too much... unfortunately.

Maybe the best bet is to put the work in a tilting vise, rough out the central channel with a .250 bit, then tilt work 41 degrees? But then I'm at a loss of how to calculate a height change so that I don't overshoot the depth of the initial cut to maintain a clean inside edge... I guess I could eyeball it.

I was really hoping I could get something that would do this in one (albeit slow) pass. The original part certainly looks like it was done that way.

Sorry if I sound clueless - I've only been machining for 3 months now.

TIA for more suggestions

[akula169]

Paul,

Excellent. Now I know what they are called

[akula169]

And wouldn't ya know it, they have 82 degree cutters! go figure...

Thanks again for the help folks!