Will these motors be overkill?

[CPierce18]

I need some assistance determining if this stepper motor package will work, or if it is overkill.

My table dimensions are 96” x 52” with the primary function of plasma cutting. I’m not interested in outstanding resolution or off the chart rapid speeds.
My X-Axis will use (2) 640oz-in motors (dual drive), direct drive with a 1.75”DP spur gear, spring loaded to the gear rack. Driving weight will be 50-60lbs

My Y-Axis will use (1) 640oz-in motor with 1.75”DP spur gear, spring loaded to the gear rack. That motor will be driving 15-20lbs.

My Z-Axis will be WAY over kill if I use this package. It’s screw drive (5/16”-18) only 5 lbs or so.
www.kelinginc.net/CNCNEMA34Package.html
Package #4… $899.00
(4) KL-5056, 24-50VDC, 5.6A Driver
(4) NEMA 34 – 640oz-in Stepper Motors
(1) 48/ 12.5A Power Supply, 110V/220V
(1) C10 Breakout Board
(1) 5V power Supply, 110V/220V

I’d LOVE to break the package up and buy a smaller motor for the Z-Axis, but I don’t have any clue what is driver is compatible with what motor and power supply. Fabrication on my table has been on hold for 6 months now because I’ve been lost with what motors, drivers and power supply to buy. Any help would brighten my day!

Could someone maybe give me hint at what drivers are compatible with what motors, and what size power supply I would need and break-out board

[Torchhead]

Originally Posted by CPierce18 I need some assistance determining if this stepper motor package will work, or if it is overkill. My table dimensions are 96” x 52” with the primary function of plasma cutting. I’m not interested in outstanding resolution or off the chart rapid speeds. My X-Axis will use (2) 640oz-in motors (dual drive), direct drive with a 1.75”DP spur gear, spring loaded to the gear rack. Driving weight will be 50-60lbs My Y-Axis will use (1) 640oz-in motor with 1.75”DP spur gear, spring loaded to the gear rack. That motor will be driving 15-20lbs. My Z-Axis will be WAY over kill if I use this package. It’s screw drive (5/16”-18) only 5 lbs or so. www.kelinginc.net/CNCNEMA34Package.html Package #4… $899.00 (4) KL-5056, 24-50VDC, 5.6A Driver (4) NEMA 34 – 640oz-in Stepper Motors (1) 48/ 12.5A Power Supply, 110V/220V (1) C10 Breakout Board (1) 5V power Supply, 110V/220V I’d LOVE to break the package up and buy a smaller motor for the Z-Axis, but I don’t have any clue what is driver is compatible with what motor and power supply. Fabrication on my table has been on hold for 6 months now because I’ve been lost with what motors, drivers and power supply to buy. Any help would brighten my day! Could someone maybe give me hint at what drivers are compatible with what motors, and what size power supply I would need and break-out board

Well, This does not answer your direct question about motors and drives but have you done the math on the drive mechanics on your table?

DUDE! That set of pinions and motors will launch your table at close to earth's escape velocity. At 48 V (which is actually too low) you will get about 650 RPM out of the drives. The rapids could be as high as 3500 IPM! (60 IPS) so you run your gantry all the way down the table in about 2 secs. Now, you don't have to set your velocity that high but for that blinding potential you have given up a big chunk of torque and (worse) resolution. The BEST average resolution you can hope for is .025 per step (microstepping is not TRUE resolution and changes with RPM). If you have any other inaccuracies they get added to the number. The torque (which is now about 20% of the raw motor) is used for acceleration. Acceleration gives you sharp corners and quick speed changes.

There are a couple of suggestions.

Get some belt reduction between the motors and pinion. You need at least 4:1 to get back your torque and help the accuracy.

Consider a smaller pinion gear. You have one now that has a 5.49 inch per rev factor (PI times the DP). Going down to a 1" drops that to 3.14 inches of linear motion per rev (still too high for direct drive). You can get by with a 3:1 belt reduction. Then you get full torque from the motors to the load and still have about 600 IPM rapids. Well over double the speeds you will need for even thin material.

Buy something more than a box-o-parts; something that has support for the control software you plan to use and the type cutting you want to do. If you are doing plasma cutting you will quickly want a Torch Height Control. Make sure your electronics can handle that upgrade without costing more than you spent on the whole table!

TOM Caudle
www.CandCNC.com
Totally Modular CNC Electronics
Low cost Digital Torch Height Controls
http://www.CandCNC.com/BladeRunner_Dragon-Cut.htm