Indexable Dovetail Cutter

[Hawkeye]

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.

 

[OakRidgeGuy]

Have you tried it yet?

 

[Hawkeye]

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:

 

[swatson144]

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

 

[DMS]

Looks great. What style insert are you using?

 

[Hawkeye]

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.

 

[swatson144]

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

 

[Hawkeye]

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.

 

[oldgoaly]

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:

 

[Hawkeye]

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.