Looking at dovetail cutters and would like to get opinions...

Hi Ron

I see many have had better success than I had. I made my own single flute cutter that was found on Bob Warfield,s site. I run it through its paces during testing, and I gave up with the single flute design. I found it would cut aluminum pretty good, but steel was a different story. Finding the sweet spot for speeds and feeds was a challenge to say the least. The 3-flute would probably do a better job, and with less hammering effect on the spindle. I havnt attempted to make one of those, maybe one of these days.

For the few jobs I used my home made cutter, I ended up throwing it in the scrap bin, and buying the HSS dovetail cutter instead. First reason was the hammering on the spindle. That sound just makes me cringe. The second thing was the inserts seemed to chip really easy. Being a single flute cutter, that was no real surprize to me, I expected it. The store bought cutter has fragile tips, and getting the feeds and speeds was key to keeping the tips where they should be. The HSS cutter with multiple flutes was much nicer to the spindle.

That 3 flute cutter might be worth a try, I would be interested to hear how that works. I havnt wanted to put my spindle through the pounding since the last go. But , If I do need a few tool holders the next time around, I have been toying with the thought of making them with bolt on dovetails to the block. I figure it should cut down on time standing at the machine, and should be able to be made plenty ridged, but this has yet to be tried by me.
 
8ntsane said:
Hi Ron

I see many have had better success than I had. I made my own single flute cutter that was found on Bob Warfield,s site. I run it through its paces during testing, and I gave up with the single flute design. I found it would cut aluminum pretty good, but steel was a different story. Finding the sweet spot for speeds and feeds was a challenge to say the least. The 3-flute would probably do a better job, and with less hammering effect on the spindle. I havnt attempted to make one of those, maybe one of these days.

For the few jobs I used my home made cutter, I ended up throwing it in the scrap bin, and buying the HSS dovetail cutter instead. First reason was the hammering on the spindle. That sound just makes me cringe. The second thing was the inserts seemed to chip really easy. Being a single flute cutter, that was no real surprize to me, I expected it. The store bought cutter has fragile tips, and getting the feeds and speeds was key to keeping the tips where they should be. The HSS cutter with multiple flutes was much nicer to the spindle.

That 3 flute cutter might be worth a try, I would be interested to hear how that works. I havnt wanted to put my spindle through the pounding since the last go. But , If I do need a few tool holders the next time around, I have been toying with the thought of making them with bolt on dovetails to the block. I figure it should cut down on time standing at the machine, and should be able to be made plenty ridged, but this has yet to be tried by me.
Click to expand...

Thanks Paul, that gives me a number of things to consider. I like Hawkeye's cutter but I was wondering how the single cutter would work on steel. As I understand it, inserts don't do well on interrupted cuts. A single insert cutter (not that three inserts makes it much better) would be one humdinger of an interrupted cut.

I do like the idea of replaceable cutters though so I guess I have to try and follow up on the idea of making one. :rolleyes: Yeah, it's a sickness. :biggrin: If I can figure out how I can do some hillbilly indexing I'll certainly try for a 3-insert cutter.

With that in mind, another thought crossed my mind last night (what a lonely walk that would be :headscratch:) concerning the cutting edge of the inserts. Granted, I am completely ignorant about the design of cutting inserts so this observation/question might be wallowing in ignorance but...

I've seen seen a number of lathe turning tools where it appears that the inserts are held so that the bodies of the inserts have a negative rake in relation to the work piece. The edge of the insert, that actually does the cutting, is formed as a very acute angle though which would put the cutting edge in a positive rake where the work piece is concerned. Hopefully that made sense. Now, the question is, is that what I'm seeing or am I out to lunch? If that's the case then not only do I need to determine the dimensions of the insert but also the angle that the insert needs to be held at to get the proper rake before one starts to make the tool.

Just another question from the "village idiot".

Thanks guys,

-Ron
 
What you are describing is a "neutral" insert. This means the cutter has no built in relief (IE, the edges and the top are at 90 dgrees). They require the relief to be built into the cutter. It's the most common type as far as I can tell. I don't think that type will work for a fly cutter, because when you angle them, you are going to screw up that nice 60 degree angle. Most of the designs I have seen us a positive rake insert. I purchased some a while back to make a dovetail cutter, but haven't gotten to it yet (as well as a million other things).
 
I've done several cuts with mine in AL, and several in 1018. It works fine but does hammer a bit, much like a fly cutter. I use TCMT 3/8" IC held with flat and square with the axis. The TCMT inserts have a 5° - 7° rake and are made to be presented to the work flat. i have yet to break an insert in it.

Steve
 
I just cannot see how this insert type of cutter will cut a "perfect" 60 deg. angle. Any angle 60.25 deg or greater I can see. For this cutter to cut a perfect 60 deg. it would have to scrape on the end of the insert, which on a light duty mill would create lots of chatter. I would be courious if someone could measure the angle cut to see how close to 60 deg it will cut. 60-1/2 deg. is not close enough for me, 60.0625 deg would work.

Anyone out there using these cutters can offer feedback on accuracy of the 60 deg angle cut?
 
Why don't one of you guys that knows what they're doing, do a simple build thread on a 3 tip dovetail cutter? That way us novices could learn to maybe make our own. I actually researched the process and made a couple of single tip dovetail cutters and destroyed both roughing out dovetails for Howard Halls delux grinder rest. That project lies withering in a box on the shelf because of other problems. It's on my warmer weather list to redo and dovetails are part of it.
At least explain what metal to make the tool out of, what size(s), and what insert(s) to use. Requirements would be commonly available affordable materials and inserts.

Chuck
 
I occasionaly use conventional dovetail cutters for recutting dovetails on slides and they work just fine. As for the 60 deg angle being correct or not? I have not had any issues with scraping and fitting them on rebuilds and new slides.
 
Hi Ron

The pic you show at the start of this post clearly shows the insert to have rake. At what angle, and what insert, I really don't know. Im assuming its a Dorian cutter, maybe they could answer that for you. 4GSR made a good point about making a true 60 degree cut. When I was try my home made cutter, I personally thought it was cutting a tad more than 60o , but I didn't go through any trouble to se exactly what it was. All I knew was the mill was trammed before the job started. The thought of making a 3-flute could prove to have its own challenges. Getting the screws indexed the same height so all 3 cutters sit the same, and do equal amount of work would be one thing. The thought of cutting a certain degree of rake into the cutter shouldn't be to hard to do. Then again, that would depend on what equipment your working with.

When I did use mine, I did notice thatit didn't cut as clean, as the HSS cutter did. So to that extent, the home brew was a roughing tool, and the store bought was to finish the job. I cant recall off hand, but when I did switch to the HSS, the cutter seemed to be removing more on one end or the other. Cant remember if it was favoring more in the root of the cut, or at the top. I did notice a difference though. I should have sprayed a bit a dykem blue to check. The multi flute insert cutter would be interesting to build and test out. If mad accurately, it should prove to be better than the single flute I had built.

What price range is the Dorian cutter worth? Probably more than one would want to pay. I have enough projects on my plat now, but if I do get bored and find time, I just might give the 3-flute a go. I will be trying the bolt on dovetails as I mentioned. Just to see how well they would work for tool holders for the QCTP.
 
I started out on mine by picking up a couple of carbide inserts at my local tool store, then building the tool around that. For my purposes, if it isn't exactly 60[SUP]o[/SUP], it's not a problem as long as I use the same cutter for both halves of the fitted dovetail. The Chinese ways were actually closer to 55[SUP]o[/SUP]. I was reworking both sides anyway.

I haven't tried mine on steel yet. The ways were cast iron, but the extension I built turned out to be white cast iron. Really tough to machine. The cutter held up pretty well, but did cut that part a lot slower.
 
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