Thread: Cutting A 6MM Wide 60 Degree Dovetail - Any Suggestions

Bob, everyone has the skill, it's up to them to realise it, in other words you can do it.
Kryn

You could always drill your 8mm hole, slot it, then heat and bend one of the sides off at 90 deg. Then use a normal cutter, heat again and bend back. It will probably never go back 100% but it should be close.

Seeing the noga one i think it could be made from a length with half the dovetail on each end and a thin part in the middle and then bent around an 8mm rod.

Ew

Originally Posted by Ueee

You could always drill your 8mm hole, slot it, then heat and bend one of the sides off at 90 deg. Then use a normal cutter, heat again and bend back. It will probably never go back 100% but it should be close.

Seeing the noga one i think it could be made from a length with half the dovetail on each end and a thin part in the middle and then bent around an 8mm rod.

Ew

Instead of an 8mm hole, you could drill it at 6mm say, then as Ewan has said, heat and bend one side off at 90 degrees, machine the dovetail with a normal cutter, heat again, bend back and clamp up on an appropriately sized male dovetail before redrilling to 6.5 to 6.8mm and finish by reaming to size. Finally polish and black to the usual BT standard.
Rob.

I slipped up to the shed and had a look at the fit of the Interapid clamp on both the Interapid DTI and the cast dovetailed Mitutoyo. In both cases the 60 degree sides of the clamp make continuous contact with the indicator's dovetail. There is clearance between the rear face of the clamp and the corresponding face on the DTI. Same with the Mitutoyo clamp.

For such a piddly thing you blokes have come up with interesting suggestions. With the rear of the dovetail doing little, I'm leaning heavily towards the slitting saw. That way there's only one thing to make, the clamp.

Bill, the DIY cutter recipe is of interest. I need to make a cutter or two for a tiny boring head. Michael G generously procured some 4mm hardened and unhardened rod for me a while back. The recipe would help me to get to it.

Chris and Michael, I have needle files aplenty but the saw sounds easier.
Ew and Rob, the heat and wrap sounds like fun but I bet I'd end up with a bin full of rejects because the dovetails didn't line up!

And Kryn, thanks for the encouragement.

BT

Do you have a surface grinder?

Gene

http://www.maritool.com/Cutting-Tool...duct_info.html

or Brownells for a .245 x 60

http://www.brownells.com/gunsmith-to...prod20728.aspx

No surface grinder Gene. A nice T and C though.

Don't know how I missed the Brownell's cutter Richard. It or the Mari are a temptation if I change my mind about using a saw.

BT

Originally Posted by easymike29

Do you have a surface grinder?

Gene

I'm betting you are thinking the same as me... grind down a larger size.. should be just a straight cut? Provided the skinny bit of the shank is small enough.

Ray

Don't quote me on this, but I recall there was one of the Dremel cutters which was close to 60 degrees (maybe 70 degrees), and fairly small (around 5mm at the widest) - obviously it's only HSS and takes shallow cuts, but it might be of use.

what I don't know is how well it would last on your material

Des

Originally Posted by Anorak Bob

No surface grinder Gene. A nice T and C though.BT

Try this

Gene

Originally Posted by easymike29

Try this

Gene

Good suggestion, but what size wheel would you be using for that? How would you accurately dress the wheel to the appropriate angle without a sine dresser or radius and taper dresser (note: points lost for losing hand and/or having a wheel explode in your face when trying to bodge something up).

The thinnest surface grinder wheels I've seen are 1/4", and accurately dressing a wheel to specific angles isn't something to be taken lightly. Sine dressers can be picked up quite cheaply, but it's still a hundred bucks or so, and of course requires one to be purchased.

I like Ray's idea of shortening a larger cutter. They can be picked up reasonably cheaply used off ebay, and the chances are the top part of it you'll grind to will be perfectly sharp and unused.

A couple of other suggestions, for what they're worth. If you have a small t-slot cutter, step across in a series of descending steps, and then just file off the steps. I think Dremel make small cutters like this and they're likely to be cheap.

I'm a big fan of D-bit cutters, so for this one-off you could look at making up an equivalent cutter as a dovetail cutter in silver steel. Take some 6 mm silver steel, turn down a shank and leave an unturned section at the end. Turn a taper on that end so you now have a dovetail blank, section it to create a D-bit, then if it's to be used in steel harden and temper it, in aluminium I'd just leave it soft for a one-off. Note I've never made one of these, but I'm currently making a threading tool somewhat similar in HSS, so grinding instead of turning, I've just got side-tracked on something else.

Originally Posted by Pete F

I'm a big fan of D-bit cutters, so for this one-off you could look at making up an equivalent cutter as a dovetail cutter in silver steel. Take some 6 mm silver steel, turn down a shank and leave an unturned section at the end. Turn a taper on that end so you now have a dovetail blank, section it to create a D-bit, then if it's to be used in steel harden and temper it, in aluminium I'd just leave it soft for a one-off. Note I've never made one of these, but I'm currently making a threading tool somewhat similar in HSS, so grinding instead of turning, I've just got side-tracked on something else.

That'd work, but if I was only doing 1 or 2 I'd mill out the clearance slot then file to fit using a safe edge file. Easy to make one, buy a new triangular file & kiss 2 surfaces on a linisher.

I used to do dovetails all the time like this, for gun sights, back when I did a lot of hunting & gunsmithing. Then I bought a lathe, then a mill and it's all been downhill ever since.....

PDW

Originally Posted by easymike29

Try this

Gene

Hey - Could "this" be done with one of those really skinny wheels off a chain saw sharpener or alternatively 100 years ago would somebody simply knuckle down and do it with a hacksaw and a file ?

Bill

There are lots of good suggestions for making the dove tail which if it were larger would be great. This thing is small though. Draw it out on a piece of paper - 6mm across the widest part and between 1 to 2mm deep. As far as grinding goes this is really Dremel territory. Toothed cutters whether D, fly or dovetail similarly are going to have to be really small. To make up a cutter for a one off job like this will take more time than can probably be justified. Even grinding the tool and setting up a shaper will take some time.

Based on all that I still think the only way to do it is to straight mill out most of the material (say around 1.2 DOC with a 4 to 4.5mm cutter) and then take out the corners with a needle file.

Michael