Making A Dovetail Cutter

[Ripthorn]

Hey guys, I am drawing up some plans for a couple parts I want to make, and they will require some small dovetails in 6061. Max width will be 1/4", 60 degree included angle. I have looked around online and found one at Brownell's for $30, but since I've never used a dovetail cutter before, I thought it might be a good exercise to make one out of O1 (which I have on hand) and try it out before potentially trashing a perfectly good cutter. I will need to cut a total of approximately 30 inches of dovetail. My plan is to use a hex block and put either 3 or 6 flutes on it. However, I haven't been able to find any tutorials on making a small dovetail cutter, only larger insert-based ones. My questions are as follows:

- How much relief should side and bottom edges get?
- How do I determine how far past center to cut the flutes?
- What is the best way to sharpen the small, triangular flutes after heat treating?
- Should the corner of the cutter be slightly rounded to reduce the risk or ruining the tool in use?

Yes, I'm a total noob in this area, so please, school me!

 

[Andre]

I've made them before, single flute out of HSS. They didn't work too well, so take my advise with a grain of....no wait a chip of aluminum?

You never plunge down with a dovetail cutter, so I would imagine simply dishing the bottom on the lathe would be sufficient for bottom relief angle.

The best way to sharpen would be on a TC or surface grinder, however using an oil stone should work.

The corners of the cutter should be deathly sharp, however if the make dovetail has a beveled corner you can get away with some corner radius on the corner.

 

[Chipper5783]

Hi Ripthorn, good topic you have started here.
I copied an approach that has been documented by several folks on their homepage web sites. Just bury a 60° insert in a small home built holder (the cutting edge needs to be on a line even with thee tool axis). When I got to the full depth, it would only allow a very small depth of cut. In otherwords, each dovetail took a quite a long time. The finished product turned out quite well, pretty good surface finish (I fussed over the measuring a lot).

David

 

[Ripthorn]

David, thanks for the response. However, the cutter I am thinking of making is so small that inserts won't work for it. I need it to cut a 1/4" major diameter dovetail, so the insert would have to be around 1/8" on a side.

 

[middle.road]

Dang. I checked my grab-bag in the shop and the smallest was Ø.375 Minor, (3) of 'em. I would have sworn I had some smaller ones...
I wonder if a carbide router bit would work, or even if they have them in 60°?

 

[Billh50]

you could try a gunsmithing supply house. Someof the dovetails are for sights are small.

 

[derf]

Buy the one from Brownells. That price is cheap compared to the frustration you'll have to make one. Dovetail cutters are fragile, don't take big cuts and don't run over 600 rpm.