JohnW wrote:
mblaszkiewicz wrote: No it was actually the table lifting and moving. The machine was designed as a high speed drill tap. All forces down.
Very useful to know! So it is not going to be my general purpose milling machine! My revised plan now then, to just get going, is to use a Closed Loop 12nm NEMA 34 Stepper for the Z, and two open loop NEMA 23 Stepper motors I have already to move X and Y, and a parallel card. This should get me in to Linux CNC, at least engraving perspex, hopefully without getting crushed by the Z axis.
Is there any way I can get the original spindle motor, a Toshiba RA10M AC Servo motor, 1.5KW, 3K rpm 6K max running off 3 phase without a VFD? Can I just wire it up to the 3 phases and run it open loop at least for a short time, say 10 minutes? Will it be going at 6K then?
no, you can only run the spindle motor with a dedicated servo drive.
the machine is very much a heavy duty milling machine with very good spindle bearings that handle side loads well - the machine has milling cycles and is very much intended for face milling and slotting. when people call it light drill tap, they are comparing it to things like a huge mori or mazak 40 taper etc (which people who run 50 tape call light duty). the tc211 will be at least as much above things like tormachs and other hobby mills in rigidity as the 40 tapers are above it.
on my tc 225, with 410w xy servos and 3.1kw spindle i can plow through aluminium with a 1/2" zrn coated cutter at 196ipm 1/2" deep, 1/8" step over 6000rpm and it doesnt make a peep. the tc 211 wont do that, but it wont be that far off, the rigidity will be similar, just not the power.
if you have the drives, use the original motors. if you dont have the drives, try to find them on ebay for cheap. if you cant find them, buy new xyz servos from delta (asd-b2) for $1500 if you can afford it. steppers would be not ideal on this machine for a number of reasons besides just performance. 1st; physical size. the servos on the brother are somewhat odd metric sizes, not nema 23/34, and their shafts are also somewhat unusual diamtres. youd need to make adapters, and get couplings and hope they fit under the way covers. you also need a brake on the Z, which is inside the servo. otherwise the axis will fall when the power is cut. on a machine as heavy as the brother, with linear guides, the steppers internal detent torque will not hold up the head.
my brothers have 86mm (looks like nema34 but isnt) and 120mm servos with 16mm shafts.delta does make a 750w 86mm motor to fit. it think on your machine that would be the Z. i think your xy might be 60mm "standard" japanese spec, which delta (and everyone else) makes in 200w and 400w.
for the spindle motor, you can do 2 things (i am assuming your spindle has an encoder, not a resolver).
1: get a drive like the delta c2000. this will run a 3 phase servo like a regular analogue spindle. the drives cost alot. probably $600-$800.
2: get a drive that runs "any" servo. delta makes the asd-a2r for this, but its impossible to find. some people have used surplus allan bradley 3000 drives off ebay. they work just fine, and in the wattage you need, arent too expensive.
thinking about it, we should check if the AB 3000 drives run resolvers. if they do, you might be able to replace all 4 drives and use the stock motors for less than 1k. these drives are not ultra high performance, but they should work pretty good for the price and be a hell of alot better than any steppers. they have been used on a TC229 conversion with reasonable success (the machine got slower than its original 1400ipm).
