DT2 vs SMini: Accuracy vs Speed?

I'm planning on adding another machine for the stamps I make later this year. Right now I run the roughing and all the design stamps on my TM2P and the production (300-400 a day) fonts on the OM2A. I've found that for these 15,000 rpm is actually the sweet spot even though it has a 30K spindle. I suspect it just can't handle the accel decel on the micro machining (0.0005" tip tool moving 3D @ 0.0004 step over) at higher feed rates. Mind you it will spend 5 minutes in a 1/4 x 1/4 x 1/32" cube at 6ipm... 1mb files all 3D paths no filter no arcs. If I speed the spindle the tools go south fast regardless of feed. At 15K I get a few hundred parts out of a set of tooling vs realizing the tool broke 40 minutes into a 7 hour run.

New machine options are DT2 with 15K spindle, or a SMini with 15K spindle. Optioned out as I need them it's the same price. Here's my question... concern: 2400 ipm rapids on the DT2. Are they sacrificing long term accuracy for blazing speeds? I couldn't care less about rapids or tool change speeds, they are completely irrelevant for my parts as the tool is in cut 90% of the time, 99% of the rapids won't get up to the speed in the distance anyways, and there are only 6 tool changes per hour at most. The OM2A is 1200 I think and i have it locked at 50% just so it doesn't jerk trying to rapid 0.029" all day and I ran two programs back to back and it lost 2min per hour while not jerking every 45 seconds trying to get to speed and failing. The DT has an extra 8" in X which is nice... but not a deal maker if the SUPER FAST rapids which will be turned down anyways are going to sacrifice even a tenth or two accuracy over 2 hours from tool to tool on the same part.

I'm thinking maybe it's just faster pitched screws but maybe i'm wrong??? Any other advantages you see from one to the other? Chip control, Rapids, TC time, HP, and CAT40/BT30 are all irrelevant. Honestly I'd prefer the BT30 less mass to spin up and down 24/7 on the spindle bearings. Floor space, accuracy and repeat-ability over 2 hours is all that really matter (with a 15K spindle)

**ADDED: by 'sacrificing accuracy' I mean I can adjust a 56TPI screw a heck of a lot easier than a 16TPI adjustment screw. I am wondering if the slower pitch would be better for micro moves in the long run.

I believe you are cprrect regarding the high pitch ballscrews of the DT2. We have one DT1 and one DM1. We don't run the type of work you do, but if we would, we would use our standard VF2 before the VF2SS.
I also think the spindle of an DT2 wouldn't last very long running 15K rpm 24/7. It's made for drilling and tapping, where the spindle is hardly running 50% of the time.

Regarding jerky rapids, can you change your CAM to output G1 moves with a high feedrate?

dallack said:

I believe you are cprrect regarding the high pitch ballscrews of the DT2. We have one DT1 and one DM1. We don't run the type of work you do, but if we would, we would use our standard VF2 before the VF2SS.
I also think the spindle of an DT2 wouldn't last very long running 15K rpm 24/7. It's made for drilling and tapping, where the spindle is hardly running 50% of the time. Not to mention I have the door open while it does the finishing ops measuring with a graduated eye loupe and prefer to get hit by a 600ipm table to a 1200ipm table if I brain fart.

Regarding jerky rapids, can you change your CAM to output G1 moves with a high feedrate?

Click to expand...

Yeah it would be 'faster' overall to change the rapids to G1s but I don't know how to get it to only use rapids at tool change, plus I share programs from the OM to the TM (40% feed override) and the TMs rapids are slow enough it works out. At 50% locked it works out well and doesn't scare the living hell out of me every time it slams the way covers at rapids. The things only 12" in X and the perceived decrease in wear in my mind is worth the few minutes a day it slows the machine.

Now the spindle is something I hadn't even thought about. The DT is a direct drive and the SMM is belt right? That means to make the 15K spindle it's likely just a different gear ratio and maybe spindle cartridge? Wondering how that would hold up at 15K rpm 22 hours a day. Anyone run their spindle full speed on one of the Super Mini's a couple shifts a day?