Testing shop made dovetail cutter

[Chuck K]

I've made several tool holders for my lathe. I've always used HSS dovetail cutters and it seemed to take way too long. I've seen tutorials on YouTube where they make indexable carbide cutters. I have a bunch of inserts that I had no use for, so it seemed like a good project. After I finished it, I made a holder and was impressed with the way it cut. I didn't push it real hard. I was advancing 0.025 per pass. That was more aggressive than I do with a HSS cutter. Today I decided to see what it could do. I finished the holder in three passes. 0.100, 0.100, and 0.037. It seemed to handle it fine. I'm impressed. The material is 4140.

 

[Winegrower]

Nice work. I made a couple of dovetail cutters but with only one insert each...fearing I would never get the tracking correct.
The only issue I encountered is that the inserts I used were on the small side, and made it a bit more difficult to cut deeper dovetails.
I will just have to make more.

 

[Chuck K]

I made one a few years ago that had three inserts. I didn't locate the screws well and the inserts kept working loose. It was a failure.

 

[silverhawk]

So how did you align the screws this time for success? What made the difference on this iteration?

joe

 

[Chuck K]

I took a short piece of 3/16 round and turned the end down to 0.128. That fit tight in the insert hole. I put a 30 degree taper above it so it sat in the insert perfectly. Then I mounted it in a collet in my mill and positioned my insert with it. When I had my position, I spotted, drilled, and tapped it. Rotated 180 and repeated.

 

[Jim F]

How much does the insert extend out and down ?

 

[Chuck K]

I couldn't tell you without measuring it. I just eyeballed it. I could measure it when I get a chance.

 

[Jim F]

I couldn't tell you without measuring it. I just eyeballed it. I could measure it when I get a chance.

No hurry, climate prevents shop time right now.
Would like to make one of those, though.

 

[rwm]

Remarkable how your inserts meet perfectly at the center! Nice work. I made a single cuter insert that just worked OK. I guess I need to revisit that.
Robert

 

[Chuck K]

No hurry, climate prevents shop time right now.
Would like to make one of those, though.

I was in the shop today and was going to get measurements for you. Short of taking the time to set it up to measure it with a height gauge, I don't know how I would do it. I basically just positioned the insert a little proud of both the side and bottom. The edges have an 11 degree relief anyway so I didn't think I needed much. (That was my assumption anyway). Having said that, I maybe should have a little more on the side. When I rough out the slot with a mill there tends to be jagged chips hanging on the edges. That stuff scratches on the tool on the first pass. It has clearance when it's cutting though. I took pictures showing the bottom and side. I don't know if it will help. It's kind of hard to see.