# Indexable Dovetail Cutter



## Hawkeye (Dec 24, 2012)

When I found out that the dovetails on Chinese ways aren't always 60o, I needed a larger dovetail cutter to recut the Y-axis ways on my X2 CNC conversion. I had picked up a couple of 3/8 inserts and mounting screws, so I just had to make the body of the cutter.

I turned the shaft to 7/8" so I can use it in the collet holder on the Victoria and in the R8 collets on the ZX-25 mill.



The holder spun nice and true when I reversed it in the collet to face the cut end.



The trickiest part of the build is setting the height and angle to cut the recess for the carbide cutter. The table on the Victoria is big enough to leave the two vises attached and bolt the indexing head on the free end. A little tight to access the working area, but it's nice not to have to re-true a vise weighing over a hundred pounds. The surface gauge I made was the only way to transfer the recess height to the end mill, then set the DRO to zero. you have to add the thickness of the carbide so the cutting surface ends up at the centre line.




Cutting the recess. You have to love the mystery metal that got magnetized at the scrappers.



The finished product. I'll try it out tomorrow.


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## OakRidgeGuy (Dec 24, 2012)

Have you tried it yet?


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## Hawkeye (Dec 24, 2012)

Not yet. So far, I've taken the X2 apart and mounted the base on the Victoria. I have a bit of Christmas running around to do, then I'll true the end of the base to take the extension block square. After that, mounting of the block. If I can do all the finish work on the extension and mount it permanently, there won't be any shifting after I touch up the dovetails.

I could be a couple of days off in testing the cutter. :biggrin:


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## swatson144 (Dec 24, 2012)

It'll work fine. The one I made works like a champ. High speed and slow feeds. You'll like it much better than HSS. 

Nicely done!

Steve


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## DMS (Dec 24, 2012)

Looks great. What style insert are you using?


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## Hawkeye (Dec 24, 2012)

I don't know what designation this insert would carry in the industrial world. My supplier is geared mostly to hobby-level interests, so a catalogue number is all you see.

It is a 3/8" incised circle, with screw hole and chip groove. I don't know the grade. I'm planning to take light cuts. The cast iron in the mill ways is much friendlier than the stuff I had on hand for the extension block, so it should go well.


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## swatson144 (Dec 24, 2012)

Looks like the TCMT 32.52 you get with a china made 1/2" indexible turning tool set. Exactly what mine is also. Mine was leftover from replacing some of the ones on the turning tool set with a better pedigree.




Steve


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## Hawkeye (Dec 27, 2012)

I finally got the extension made and mounted on the base for my X2 mill, so it was time to try out the dovetail cutter. It did a nice job of reshaping the dovetails on the mill to the normal 60[SUP]o[/SUP]. No idea why they used an apparently arbitrary angle.



The copper tube is for the air jet to clear chips away from the cutter.



The finish turned out quite smooth. I used the slowest feed rate the Victoria could do, so each pass took quite a long time. The only problem was with the mystery cast iron I was using. It was a lot harder than the material in the base of the mill, so it ended up a bit higher at the join line, even after several spring passes.



All in all, it was well worth the time to make the cutter. Especially when you consider that a commercially available one is over $200.


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## oldgoaly (Dec 28, 2012)

Thanks for sharing your build! it has me very interested in making one for a project. I need to make some dovetails for power hammer dies. I do believe they are 45 degree, and the die material will be 4140 steel (truck axle blanks)  Here is a pic, not the best angle but it is the best I could find, and it is snowing like heck!!! 




Could one make a cutter similar? would you recommend a positive or negative rake insert?  Thank you for your time and knowledge!!! tt:thumbzup:


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## Hawkeye (Dec 29, 2012)

Those actually look like more than 45[SUP]o[/SUP]. I'd measure them to be sure. 60[SUP]o[/SUP] is easiest to make, since you can use triangular carbide inserts. 

If it's less than 60[SUP]o[/SUP] you'll need a diamond-shaped insert with the narrow ends at 35[SUP]o[/SUP]. Your cutter will hold the insert with the rising edge at the required angle. The tip will cut the flat surface as it turns.

I used the only inserts that were available locally. They have the edges tapered back, so clearance was built in. The mounting surface is parallel to the axis of the shaft.


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## DMS (Dec 29, 2012)

Those look like 60 deg to me OldGoaly. Could be the camera angle, buy you might want to double check.


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## oldgoaly (Dec 29, 2012)

yep it's a 60!!!! worth the trip in the snow to figure it out. now to read up on what cuts 4140/truck axles best, I've only got about 8 of these, not real sure if they a p or n rake (dang tag is off the little package). I've got about 6 dies to make with dovetails. Thanks for the help guys!  looks like my poor old B/P will get a work out ...again!


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## Hawkeye (Dec 29, 2012)

Those inserts are similar to the one I used. I'd cut the holder straight. The grooves give it plenty of positive and the sides should already be angled back for relief.

I set mine up so that the cutting face of the insert was on the centre line of the shaft. Above centre gives negative rake; below centre gives positive.


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## ScrapMetal (Feb 13, 2013)

If I may ask, where did you find the dimensions for the inserts?  I know 60° is 60° :biggrin: for these triangular inserts but having the size and thickness would be helpful.

Thanks much,

-Ron

P.S. Crud!  Posted this to the wrong thread and couldn't delete.


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## Hawkeye (Feb 13, 2013)

Ron, I started by buying a couple of inserts at my local tool store, then building the holder around that. The step is offset to put the top of the insert on the centre line.


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## DMS (Feb 14, 2013)

You probably want something like this

http://www.use-enco.com/CGI/INSRIT?PMAKA=422-2863&PMPXNO=7908808&PARTPG=INLMK32

It's a TCMT 1/4" IC. If you want a slightly bigger one, grab the 3/8" IC. The thing you want is the clearance (second letter something other than N).


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## ScrapMetal (Feb 14, 2013)

Thanks guys.

-Ron


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