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

Brownells gunsmithing supplies in the USA.

PDW

Originally Posted by Anorak Bob

Any other recommendations will be appreciated.
Bob.

What about an upgrade... The Noga FA1500 http://www.noga.com/nogaProducts.php?prdID=FA1500

http://www.ebay.com/itm/Noga-Fine-Ad...item2ed7b9cc77

Ray

BT,
How could you mention using a file in the same sentence as as a shaper. As a mates father said "a shaper is just a lazy mans file"
I use any excuse I can so the shaper can "pay" for its space. lol
How many are you going to make?
I'd be thinking about machining the dovetail first in the a piece of stock say 100mm long. I assume you'll want to cut the slot last so I'd make the blank twice as long and "double ended" so you've got something to hold onto. Though 16ish sound like a lot.

Stuart

Hi Bob. What Stuart said. That job sounds like its sceaming out for a shaper!

Cheers.

Simon

Bob what size is the dovetail you need to make? I'll scratch around here to see what I have. Also what material are you intending to make the holder out of?

Other possible solutions would be making a single point fly cutter, or even a conventional cutter if you're keen enough! The latter not as crazy as it may sound, especially if you were to choose aluminium. I'm about to make a miniature threading bar and a similar process could be used to make a dovetail cutter. I'll put up the process here if you're interested? I'll grind mine from HSS but a similar process could be used by turning some silver steel and hardening it after turning.

The final solution would be to suggest that instead of making a one off tool just to do this one job, triangular inserts are 60 degrees

I'd make the clamp in two halves, this would make cutting the vee very simple.

Ken

Thank you all for the replies.

Peter, I checked out the Bownell's site, the cutters are either the correct 60 degree angle but too wide or the correct width and the wrong angle. That led me to a gunsmithing site where there was a discussion about a DIY option - http://www.homegunsmith.com/archive/T550.htm

Ray, I "upgraded" to a Noga a few years back but the adjuster struggles with the weight of a Compac 58mm DI. https://www.woodworkforums.com/showth...03#post1305203

Stu and Simon, if my Douglas doesn't start paying for its keep it might well be out the door. It is probably two years since it's been used. And I would only be making one of these clamps.
I take your point Stu about oversizing the piece to have something to hold on to.

Pete, the clamp's dovetail is only 6mm wide at its widest point. I'd probably use 1045 or 4140 because I have both and neither rust as suddenly as that gumby 1214.

And Ken, while a two piece clamp would be the easiest solution, dovetail cutting wise, the other end of the one piece clamp on the original incorporates an 8mm diameter hole for attachment of lugless back dial indicators of which I have a few. A clamp that pinches the stem is a bit simpler than a two piece affair that has to both clamp via the dovetail or by the hole.

BT

G'day Bob,
As the dovetail is only to hold an indicator is there any reason the bottom angle really needs to be 60⁰?

Given this, you could cut your dovetail in a couple of passes with just a normal end-mill similar to the following:
Cut 1: Tilt head to cut first 60⁰ slot.
Cut 2: Tilt head to cut opposite 60⁰ slot.
Cut 2.5 (Not drawn) Drill relief hole for the spring slot
Cut 3: Use slitting saw to cut spring slot.

A bit fiddly but job done.
Cheers,
Greg.

Neat Greg.

Thinking the bottom needed to be flat steered me away from using a slitting saw or bitty endmill to cut the dovetail. Makes sense that only the sides and back corners could do the clamping.
Some of the Mitutoyo DTIs I have have integral cast dovetails. It will be interesting to see through a scope how much actual engagement there is.

Bob.

Bob, I buy dovetails from AB tools in the US but I think they only go down to 1/4"

Harvey have smaller:

http://www.harveytool.com/prod/Dovet...utters_84.aspx

Costly for a 1 off at US$60 or so.

Neil

Originally Posted by Neil317

Bob, I buy dovetails from AB tools in the US but I think they only go down to 1/4"

Harvey have smaller:

http://www.harveytool.com/prod/Dovet...utters_84.aspx

Costly for a 1 off at US$60 or so.

Neil

Certainly not stuff for the heavy handed! A 1/16" dovetail cutter!

Thank you Neil.

I like Greg's method but while not a 100% sure, suspect that the dovetail may be one of the type that requires a flat back (is there a clean metal surface for the points of the clamp to sit or are the surfaces the back and sides of the dovetail).
I needed to do a similar thing for the indicator holder I made and ended up milling a straight section for depth (around 2 or 3mm) and then using a needle file to make the undercuts. Did not take long at all.

Michael

Hi Bob,

Are you handy with files? I honestly believe one can file this small dovetail in less time than it takes to do it in a mill. A trinagular file just happens to have 60 degrees angles. Instead of spending money for a rarely used, tiny, fragile and expensive dovetail cutter, you could buy yourself a set of fine and coarse swiss needle files. You do not even have to do a precision job - its only to clamp a very lightweight measuring instrument, and if you end up with either a 58 or 62 degree dovetail will not matter one iota.

Originally Posted by Neil317

Bob, I buy dovetails from AB tools in the US but I think they only go down to 1/4"

Harvey have smaller:

http://www.harveytool.com/prod/Dovet...utters_84.aspx

Costly for a 1 off at US$60 or so.

Neil

Not necessarily for a one of job, other people may wish for one also!!!
Kryn