wfrancis
Aluminum
- Joined
- Apr 18, 2012
- Location
- San Francisco, USA
I mostly use HSS on my 10EE but I have a project coming up where I will need to remove a lot of steel so I purchased a Dorian MCLNR08-3A 1/2" shank tool holder and some CNMG 322-PM inserts. The holder is negative rake which is new to me.
I did some test cuts on 1" to 1.75" mild steel of a couple different varieties and while I got fairly satisfactory results at ~1500RPM at ~.030 DOC (shiny, reasonably smooth cuts) but the whole lathe rung like a bell. You could actually put your hand on it anywhere and feel the whole 3200 lbs vibrating a deep ringing that didn't change much with RPM.
I have a 5HP VFD driven motor that did not slow down or complain in the least. I don't think it noticed.
I did everything I could think of to reduce potential chatter. The 8" chuck was tight everywhere with the work close, I checked all the gibs, there's no unnecessary overhang on the tool, etc. Like mentioned above it wasn't at only one RPM so it doesn't appear to be a limited harmonics issue. It only did seem to ring when the RPMs were fast enough for the SFM to be in the range where the carbide "worked" correctly and it would go from rough finish to shiny only with RPM change.
I know the insert gave effectively a small amount of positive rake but I'm wondering if it's a little too blunt. I know carbide isn't as sharp as HSS but this particular kind of insert seems bit dull even for carbide.
I'd love to hear the experiences of anyone using negative rake tooling successfully on the 10EE especially if it's an insert that will work in my tooling
Thanks,
Will
I did some test cuts on 1" to 1.75" mild steel of a couple different varieties and while I got fairly satisfactory results at ~1500RPM at ~.030 DOC (shiny, reasonably smooth cuts) but the whole lathe rung like a bell. You could actually put your hand on it anywhere and feel the whole 3200 lbs vibrating a deep ringing that didn't change much with RPM.
I have a 5HP VFD driven motor that did not slow down or complain in the least. I don't think it noticed.
I did everything I could think of to reduce potential chatter. The 8" chuck was tight everywhere with the work close, I checked all the gibs, there's no unnecessary overhang on the tool, etc. Like mentioned above it wasn't at only one RPM so it doesn't appear to be a limited harmonics issue. It only did seem to ring when the RPMs were fast enough for the SFM to be in the range where the carbide "worked" correctly and it would go from rough finish to shiny only with RPM change.
I know the insert gave effectively a small amount of positive rake but I'm wondering if it's a little too blunt. I know carbide isn't as sharp as HSS but this particular kind of insert seems bit dull even for carbide.
I'd love to hear the experiences of anyone using negative rake tooling successfully on the 10EE especially if it's an insert that will work in my tooling
Thanks,
Will