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View Full Version : What angle dovetail cutters do I want?



Your Old Dog
08-30-2005, 07:07 AM
The change jar is full so maybe I'll get some dovetail cutters!

I expect to work 6061 mostly making brackets and adjustable fixtures for cameras. I'm trying to weigh the pros/cons of 45degree vs. 60 degree.

I'm thinking that the 45 degree bit might be more durable for a rookie mill operator. Is that a factor?

Does the 60 degree bit offer greater wear resistance to manufactured parts as more metal surface?

With my limited math background, would layout work be simpler with the 45 degree? ( I can damn near work out all problems on a sketch pad without need of calculus/trig )

These cutters are expensive and I'd like to get what will work for me, not simply the best out there. If it's the best and I can't use it then it won't help much http://bbs.homeshopmachinist.net//biggrin.gif

I have no dovetails now, will be fitting a R-8 adapters on a geared head mill/drill. What would be good for me to start with?

thanks.

[This message has been edited by Your Old Dog (edited 08-30-2005).]

Mcgyver
08-30-2005, 09:16 AM
I've only done 60's, don't know if I've seen 45 - are the a camera thing? Dovetails are not difficult to cut, esp in AL. If anything the 45 cutter would wear more quickly because its removing more metal, but the usual culprits are going to determine wear. chip clearance etc might be a PITA as it is a'less open' cut and 45's would be a real PITA to scrape!

Someone here will know what the 45's are for, but pending a revelation, go with the 60

ammcoman2
08-30-2005, 09:27 AM
Hi there.

I have cut both and there is no real difference in the method or ease thereof. I just go real slow and cut only one surface at a time.

One thing however, is that 60 degree cutters are cheaper for a given height since the diameter is smaller.

Good luck.

Regards,

Geoff

Paul Alciatore
08-30-2005, 09:47 AM
60 is more commom. But the 45 has a larger face so would wear better - not a lot.

I use a CAD program to design the dovetail and then add circles to represent measurement pins to the drawing. I dimension the distance between these circles and have a measurable dimension that I can cut to.

Paul A.

Dick Plasencia
08-30-2005, 12:38 PM
In the optics business, cameras, telescopes, etc. the usual dovetail is a 60 degree. I have not seen 45 degree dovetails except on some machines.

Dick

Forrest Addy
08-30-2005, 12:57 PM
Go with 60 degrees. These are straight flute form cutters and they have a tiny neck that's easy to break. In aluminum they clog easy unless you use plenty of coolant.

Since they are a form cutter they're a pain to sharpen. Usually the cheap ones are shipped straight from the heat treat without a final sharpening. Examine them carefully and stone away roughness on the face of the flutes and the cutting edges while maintaining the clearances etc.

Move right along with the feed rate. These cutters do not like to dwell even in aluminum. Since you have propably 3 cuts to take for each dovetail angled surface and a final clean-up cut on the flat face one cutter will last about long enough to cut about 3 sets of dovetails. It's a sad fact of life that DT cutters soon dull.

Hint. Sharpen up your math and learn to figure pin sizes for mating dovetails. In the end cutting to pin sizes saves a lot of time and gets better fits.

Another hint: Use a different grade of aluminum on each mating dovetailed part: 6000 series on one and 7000 on the other for example. The different alloys will wear better and be less likely to gall.

webbch
08-30-2005, 02:54 PM
<font face="Verdana, Arial" size="2">Hint. Sharpen up your math and learn to figure pin sizes for mating dovetails. In the end cutting to pin sizes saves a lot of time and gets better fits.</font>

What is "cutting to pin size"? Is it cutting the dovetail and inserting a certain diameter pin into the groove and measuring the distace between pins on opposing sides of the DT grooves?

Chad

Nick Carter
08-30-2005, 03:57 PM
Talking to the folks at Taig they said they wished they'd gone with 60 instead of 45 when they started making the lathes because the tips of the 45 deg. cutters are more fragile than the 60 deg. cutters. But once you start you're stuck with the design (just ask Sherline with their odd angle dovetail)...
So if 60 will work then I'd go with that.

Your Old Dog
08-30-2005, 08:58 PM
Thanks for all your help. I confess I was confused by much of what I read here until I went to MSC and looked at each cutter. Here I had mistaken the 45 degree for the 60 degree. So if my earlier observations look out of whack they are because I had identified them incorrectly. I can see where the 60 degree would have the stronger tip. I always liked firm strong tips http://bbs.homeshopmachinist.net//biggrin.gif I will go with the 60 degree set to start with.

Thanks again for all the help.

egpace
08-30-2005, 11:27 PM
If the dovetails are far enough apart, you can rough them out by fly cutting using a boring bar with the toolbit ground to suit. Your cutters will stick around a lot longer if you just use them for finishing.

http://www1.mscdirect.com/CGI/NNSRIT?PMPXNO=1761280&PMT4NO=0