Thank you, David,
Thing is, it only does it at abrupt starts/stop, quick direction changes (like cutting holes with a pocketing toolpath), and when running at very slow speeds, e.g., 5 ipm on a Ref All. There is practically nothing when running at normal speeds. Not saying it's not the steppers, R&P drives or stepper drives, but if they have something wrong with them, wouldn't you expect some symptoms at 100-300 ipm?
The drives are Gecko 203Vs mounted to a huge heat sink which is exposed to ambient air, and with a fan in the control box. The 203Vs have a great reputation for reliability. I'm not sure what I would do to check the the Gecko drives.
FWIW, I was using all of these drive line parts on my previous machine, and all worked perfectly right up until I dismantled it last October. What supports bracing as a possible cause is the compete lack of resonance/chatter/vibration/shaking on my old 4 x 4, which used light weight 1530 extrusions (vs the 3030 full weight I'm using now). For the first machine, I built the base out of two 60" long x 24" deep cabinets. I made them out of torsion boxes for the sides, center divider and top. The torsion boxes, and the other cabinet elements were all made from plywood - no MDF anywhere. Each cabinet had 6 adjustable feet, and I made the feet out of carriage bolts and hockey pucks. It's a great combination, which helps dampen vibration. Nothing on the old machine moved (or vibrated, etc.) that wan't suppose to. So, while it makes sense to check the drive line, my recent experience with the running gear suggests it should all be A-OK.
Also, when I started this build I went over the R&P drives and looked for any looseness or play anywhere. None I could find. I removed the steppers from the drives and tuned them again to the Geckos. Frankly, i couldn't get much noise out of them through the full trim range. I adjusted to as quiet as I could and moved on. The steppers are the NEMA 34s CNCRP/Avid CNC sells. 960 oz-in, 7 amp and only 2mh inductance. Never a problem with them. I'm not sure what more to check, or how to check it.
And yes, I'm starting to wish I stayed with the tried and true and reused the cabinets. It would have saved the cost of all the leg parts, 80/20 milling charges, and the time I spent milling the extrusion ends on all the base parts. It was a considerable amount of time. As much to the point, staying with the cabinets might have prevented this problem from occurring. If I could bear the thought of breaking down the machine and going through another full assembly, I'd just change back over to the cabinets and call it a day. Depending upon how it goes, I may end up there anyway. I sure hope not.
Why break down the machine, you might ask? Because the process of lifting it would probablyl tweak the flat/square/level I worked so hard to achieve, and would require disassembly and reassembly anyway. There is a lot of weight, and it's just bolted together. Even a couple of thousands off would mean a teardown. Yikes!!! Just mentioning it makes my head hurt. :drowning:
Gary