[NIC 77]

I took the liberty of drawing up a couple ideas real fast. Nothing polished about it, it's just easier to draw it than to try and explain it. Please use all, some, or none of the concepts here, it's up to you .

I used the same 80x80 and 80x120 extrusions. Those are Rexroth size 25 rails and a 25mm ballscrew....simply because that's what I had some drawings of to modify.

To assemble this there would be many countersunk socket head cap screws throughout.

Attachment 446306
Attachment 446308
Attachment 446310

Yellow: Countersunk socket head cap screws bolt this into the T-Slot, leaving the rest of the plate to be drilled and tapped as desired.

Blue: The 80x80 and 80x120 extrusions

Orange: Chip guard....the idea is that any flying chips that can get over this will most likely have enough energy to miss the linear rails and ballscrew....I would be more concerned about getting chips in the ballscrew as the wipers on the linear rails are usually pretty good.

Red: Rest for your Cat Track / Drag Chain....

Hope this helps with your concept design....I really like the concept from LinuxFan of bolting aluminum plate together and filling with epoxy concrete...but I tried to go with the same extrusions you want to use.

Like I said, not trying to steal your thunder, I won't be offended in the least if you go a different direction. Just some ideas.

How long are your ballscrews in your design?

[NIC 77]

redding,

I should have read your post more carefully before I made mine.

So you already bought your motors? The reason I asked what the lengths of your ballscrews are is because I was thinking of doing some math to show you some theoretical differences that gantry weight would have on your design using a few different motors.

So what motors did you buy? I would need a torque vs speed graph for them (preferably a table of RPM vs Torque in Nm with 14 points) and the rotor inertia in kg*m^2 as well as the ballscrew lengths if you want me to do this.

[redding]

So you already bought your motors? The reason I asked what the lengths of your ballscrews are is because I was thinking of doing some math to show you some theoretical differences that gantry weight would have on your design using a few different motors.

So what motors did you buy? I would need a torque vs speed graph for them (preferably a table of RPM vs Torque in Nm with 14 points) and the rotor inertia in kg*m^2 as well as the ballscrew lengths if you want me to do this.

This would be very very useful - I'd love to learn how todo do this also. Yes I have got these NEMA34 Motors "86HS11860A4" driven by DMA860 controllers (same as MA860).

Ball Screw Length (between Floating/Fixed ends - inner distance):
Y: 628mm (700mm total length)
X: 528mm (600mm total length)
Z: 185mm (250mm total length)
Rotor Inertia: 1800g/cm^2 which I converted to 0.00000018 kg/m^2
RPM v Torque: Attached - Similar motor (in RPM vs Nm @ 48V), but also attached this motor PPS with 60VAC. I think just refer to the similar motor graph will be fine.

[NIC 77]

This would be very very useful - I'd love to learn how todo do this also. Yes I have got these NEMA34 Motors "86HS11860A4" driven by DMA860 controllers (same as MA860).

Ball Screw Length (between Floating/Fixed ends - inner distance):
Y: 628mm (700mm total length)
X: 528mm (600mm total length)
Z: 185mm (250mm total length)
Rotor Inertia: 1800g/cm^2 which I converted to 0.00000018 kg/m^2
RPM v Torque: Attached - Similar motor (in RPM vs Nm @ 48V), but also attached this motor PPS with 60VAC. I think just refer to the similar motor graph will be fine.

OK....that's 0.00018 Kg*m^2 no worries.

I think you got the X and Y reversed? I'm only interested in the total length of the ballscrews for this calculation....so I will use 700mm x 2motors for the long axis and 600mm x 1motor for the gantry.

The motors you posted, there are definitely two different motors there, One weighs 3.8 Kg, and the CNCRP 960 weighs 3Kg. Both seem to have about the same inductance of around 2 mH (CNCRP 960 of 2mH and 86HS11860A4 of 2.1 mH). One has a body length of 100mm and the other of 118mm. More holding torque on the ones you bought, but more torque at low RPM can't help you.

Looking at the torque chart for the 86HS11860A4 @ 60V, I am assuming that the pulse per second is the same as steps per second with no microstepping. So at 4000 PPS, that would be 4000 / (200 Steps per rev) = 20 Revs per second or 20x60 = 1200 RPM. That's about 1.75 Nm of torque on that chart, while the Avid CNC 960 Oz In (I call it that, because it's the Nema 34 they use and that's where the chart came from) is at 1Nm at 1200 RPM and 48V.

Yeah, it's probably fair to use the second graph at 48V as a comparison, and I assume the 2000 pulse in that chart means that it was tested at 10x microstepping. Good news, because I have several of these motors and I've already inputted the torque chart.

It's not really going to matter though. I can tell you right now that for a dual driven gantry using these motors, a gantry weight of several hundred pounds is no big deal with a lead of 10mm. We'll see if your Y axis can keep up at 5mm lead, and what the effects of weight and lead have on performance when I do up some graphs.

Once I've done up those graphs, I'll take a back seat for a while and stop crowding your thread.