Hi all; I feel that I abuse this forum by always asking what seem to be stupid questions but since I'm a noob with no where else to go, I always end up back here. Additionally, this post is a bit of a vent as well as contains a lot of details so it's very long. Sorry about that
Milling on my X2 seems to be getting progressively worse - I really don't know how to describe it better than that. I swapped the gears out for a Steele belt drive and screwed up the spindle in the process so I replaced both it and the pair of bearings. The problems SEEM to have started right around there though I might be totally mistaken. The bearings certainly get much hotter than they used to but that might be due to the increased RPM.
As of right now, I'm using Mach 3 (vs EMC which I used to use and it might also be part of the trouble as it doesn't "feel" like it feeds quite as well as EMC does) and MasterCAM X4. I've gotten pretty good at MasterCAM and finally have it making everything as I'd expect it.
The problem is several fold - I get "screwed up edges" all over the place. This seems to occur near holding tabs the most but sometimes it's just on a flat. I assume this is due to some sort of deflection, I really don't know. This has been happening since the beginning and the deeper the cut the worse it gets.
Also, I've been breaking end mills CONSTANTLY. I've broken four 1/8" HSS end mills today alone. I've basically broken an end mill every other part. This seems to be getting SIGNIFICANTLY worse. To make it more frustrating I've not been able to tell why several of them broke. Usually I've made some stupid and obvious mistake, but these are breaking with no warning and no clear reason why.
Additionally, I now get "rough edges" on all the cuts - basically the swarf is often attached to the lip of the cut. Not sure it's true welding as it's not that severe but it's there none the less. This absolutely started with the upgrade to a belt drive. I'm assuming it has to do with no coolant and the higher RPM but I want to be sure.
Finally, there are occasionally "steps" in the cuts. Flat spots on a curve (does NOT appear to be backlash-style, most like just an odd missed step or something) as well as rough edges on a circle. This seems to have started getting much more noticeable around the switch to MasterCAM but I'm not positive of that either. I'm simply a lot more away of what to expect in general.
I almost always cut 6061 aluminum and I use WD-40 for lubricant and vacuum off the swarf several times per operation. MasterCAM is automatically calculating the speed at ~4 IPM while cutting and a plunge rate of ~2 IPM. The RPM is around ~4300 which is the max my spindle will do. I accidentally had the IPM running at ~6 for a while and to be honest, I broke no more bits than I do now and the cut quality was just as good. That's why it took me so long to notice I had it wrong. MasterCAM was using 4-flute HSS end mills to calculate while I use 2-flute. My depth of cut is always .025" when cutting, facing, or peck drilling. How you guys are able to get a 1/8" end mill to cut 0.125" in a pass is totally amazing to me. I'm breaking them on that 0.025" pass as the picture shown proves.
For clamping, I use a hold down set as well as some flange nuts to pin the piece in place. I used to clamp to wood but when I tightened the material tightly the wood compressed and caused the center of the material being cut to bow up. I now use scrap aluminum as the sacrificial material. Honestly, other than the bowing when I overtightened, I've not noticed any other difference between aluminum vs. wood as a sacrificial material. My end mill holders are all Tormach which I love when I'm not breaking bits and is MISERABLE when I am due to the time it takes to mount and measure a new bit.
As for backlash, I have ~0.003 in the Y axis, ~0.002 in the X axis, and ~0.001 in the Z. I've enabled compensation in both EMC and Mach 3 to address this and measured backlash is now less than 0.001. Some set of the problems has stemmed from things coming loose - the gib screws on the z axis were able to miraculously back themselves out and create a great deal of slop (and wasted parts) before I realized what happened and fixed it.
So after all this, I'm getting the problem is a combination of no flood coolant with higher RPM, possibly missing some steps due to Mach 3 being so damn finicky on some machines (very high end machine and it still doesn't give me nearly as smooth pulses as EMC - not even in the same league) , user error, and ...? I'm just not sure that those things really account for all the problems so that's why I'm here.
I hope this provides enough details for the experts to chime in. I'm pretty desperate here, I was planning on competing at the RoboGames competition in a few weeks but to be honest, I've struggled so much getting parts made that it's highly unlikely at this rate that I'll be ready. I literally planned on months to make the parts and it takes me hours to make a single part good enough. Hell, I bought the Tormach stuff to speed up tool changes - I was that desperate to try and get more productive. In reality, I'm running into MORE problems now than when I first started milling. Low quality, inaccurate cuts, breaking bits - it's enough to make me rip my hair out. My wife is about to make me sell this damn mill just to keep me from driving her up the wall with my own frustration. If someone is interested in buying it, I might be open to the idea to be honest. Any help would be greatly appreciated at this point. Thanks!