- Joined
- Jan 20, 2016
- Messages
- 602
I have wanted to try negative rake inserts on my PM1030v lathe for a while. I found a pack of 10 WNMG inserts for $12 recently and decided to give it a go. I ordered some 12L14 steel to make the holder with, but its taking forever to ship, and I got antsy. I went ahead and made one out of aluminum I had on hand.
The holder will use a clamp and a 6x32 screw to hold it in place and it will have a -5 degree rake. The particular inserts I bought were Eurocut WNMG-433 IPK inserts and I couldn't find any information on them anywhere. No matter though, I don't need specifics to experiment.
Cutting the body was pretty simple with the CNC. I just modeled it up and cut it out. Cutting the insert pocket was a little bit more difficult. I had to hold the holder itself at a 45 degree angle, then tilt the entire body up at 5 degrees. I couldn't think of any easy way to do that besides making a fixture. I cut a little 3"x3" plate with .250 pin holes and 1/4x20 threaded holes on a .5" alternating grid. Then I used 3 pins to position it and 2 small clamps to hold it down.
Here is the fixture with the part sitting on it:
Then with the clamps in place.
The fixture was put in the vise and a simple cell phone level was used to angle it at 5 degrees. Then the pocket was cut and the hole was drilled and tapped. The finished product ended up being a bit too big for my lathe and I couldn't get the tool point low enough in the tool holder. That was fixed by sticking it back on the mill and just facing off the bottom a few times. Here is the finished product.
I didn't bother making the clamp for the aluminum one. I doubt it will be used much before I make the steel one. I tested it out and was pleased with the results. I had low expectations as I have read "small lathes can't use negative rake inserts" more times than I can count and its in an aluminum holder with a screw holding it down (not designed to be held with a screw).
With a piece of 12L14 round, I could cut .08" deep (.16" off diameter) and it made an excellent chip with a great surface finish. In 1018 steel, I could do about .05" deep (.1" off diameter) again with a good chip but crappy surface (I have yet to get a decent surface finish with this material anyway).
All in all, I would call it a win to get a negative rake insert with 10 cutters (60 cutting edges) that works well on a small machine for about $14 and 3 hours of my time.
The holder will use a clamp and a 6x32 screw to hold it in place and it will have a -5 degree rake. The particular inserts I bought were Eurocut WNMG-433 IPK inserts and I couldn't find any information on them anywhere. No matter though, I don't need specifics to experiment.
Cutting the body was pretty simple with the CNC. I just modeled it up and cut it out. Cutting the insert pocket was a little bit more difficult. I had to hold the holder itself at a 45 degree angle, then tilt the entire body up at 5 degrees. I couldn't think of any easy way to do that besides making a fixture. I cut a little 3"x3" plate with .250 pin holes and 1/4x20 threaded holes on a .5" alternating grid. Then I used 3 pins to position it and 2 small clamps to hold it down.
Here is the fixture with the part sitting on it:
Then with the clamps in place.
The fixture was put in the vise and a simple cell phone level was used to angle it at 5 degrees. Then the pocket was cut and the hole was drilled and tapped. The finished product ended up being a bit too big for my lathe and I couldn't get the tool point low enough in the tool holder. That was fixed by sticking it back on the mill and just facing off the bottom a few times. Here is the finished product.
I didn't bother making the clamp for the aluminum one. I doubt it will be used much before I make the steel one. I tested it out and was pleased with the results. I had low expectations as I have read "small lathes can't use negative rake inserts" more times than I can count and its in an aluminum holder with a screw holding it down (not designed to be held with a screw).
With a piece of 12L14 round, I could cut .08" deep (.16" off diameter) and it made an excellent chip with a great surface finish. In 1018 steel, I could do about .05" deep (.1" off diameter) again with a good chip but crappy surface (I have yet to get a decent surface finish with this material anyway).
All in all, I would call it a win to get a negative rake insert with 10 cutters (60 cutting edges) that works well on a small machine for about $14 and 3 hours of my time.