Automation Direct Steppers

[justCNCit]

http://web4.automationdirect.com/adc...ives_-z-_Power

and 3 of these

http://web4.automationdirect.com/adc.../STP-MTR-23079

Anybody have any experience with them. The plan is to use that setup to control my steel 3 axis CNC router to mill wood and if possible soft aluminum. They can handle this, yes?

[andy_ck87028]

I would ensure you get a solid answer before you go ahead with these motors.

I also am building a steel 3 axis ( cutting footprint 800 * 1200 * 200) and I was recommended minimum 400oz/in stepper by this forum.

Since then I have gained an impression that the advice was good.

My gantry is quite heavy and missed steps would cause me a constant headache.

I am not an engineer and so I hope my feedback does not mis-lead.

Andy

[eman5oh]

It will dpend on the type of drive system (ball screw , belt, ect) and the lead of the screw or the pitch of the belt. Those motors should drive a decent sized machine, if the mtion is smooth and a reasonable pitch is used for the drive. For the money I would buy Gecko G202 drives, as they can handle more voltage and current as well as cost less money. Eric

[justCNCit]

hehe. . went ahead and ordered them yesterday, anyways.

I hope these motors work out. Wasn't aware of exactly what setup would be best and most cost effective, was aware that Automation Direct has fairly cheap prices though and that the motors should be able to power the setup.

While the motors are on the way, why don't you all make me feel bad about my purchase. Setup:

64" Y axis
33" X axis
7" Z axis

Gantry and frame are bolted from 1.5" square tube 1/8" wall. The works are built to be bolt adjusted using a dial indicator and magnetic base.

The reason I was confident about these motors working wasn't because I'm an engineer, but because in the popular book 'How to build your own shop robot' with the big yellow machine, the author used 166 oz in motors to power a setup larger and bulkier than mine.

While his setup was a few feet bigger in each direction, mine is smaller and will run 283 oz in motors with a 2.8A drive whereas his motors were driven by a custom made 1.5A drive.

edit: oh, and for the time being the plan is to run regular ACME type hardware store screws with either a regular tapped hole on the gantry or possibly anti backlash nuts depending on what CNC zone says about them.

[justCNCit]

Maybe I was a bit hasty. I didn't read the tech sheets properly and thus didn't realize that their drivers don't operate in full step mode.

Now, for some machine specs:

- Gantry: +/- 50 lbs, + Router (probably about 30 lbs)

Still looking at the 200 oz in steppers and a 2.5amp drive. The lead screw will probably be 10 TPI. The machine length, from Y0 to Y max is 67 inches, and 33 inches of x travel. Z travel is roughly a foot. So what do you guys say, will the 200 oz in ones do the job.

This time I'm looking at purchasing the 3 axis combo from xylotex.

ps. until I can afford ball screws acme will be used with an anti backlash nut.

[jeffs555]

With a 1/2 inch 10tpi screw and plastic nuts, 200oz-in of torque will generate about 320 lbs of force. The problem is that the 200oz-in is static torque. According to the torque curves for that motor, at 450 rpm (ie 45 inches per minute) the torque will be only 100oz-in, and at 750rpm it is down to 50oz-in.

As long as you have good slides, it will take little force to move even a heavy gantry. The problem is that a heaver gantry has more inertia, so it takes more force to accelerate and decelerate it. Those motors should work, but will probably take a long time to accelerate and decelerate, and the maximum speed will probably be rather slow.

[justCNCit]

Thanks, it is a relief to know that. I'm not expecting to have a crazy servo like performance out of it, because less than 1% of the time it will be rapiding anyways with the g-code I have for it.

These plastic nuts you speak of, are they some sort of anti backlash nut? I had in mind a hand crafted type I was about to make in the shop, with two threaded holes and a tensioner.

I know the crosslides are decent on it also, free movement shouldn't be a problem. Looks like I'll be ordereing that xylotex setup soon.

But would you recommend using a 400 oz motor instead?

[jeffs555]

I said plastic, because unless you use ballscrews, there will be friction. Different materials for the nuts have differing coefficients of friction. Without looking at all the parameters, it would be hard to say what motor to use. Here is a link to a free motor sizing program that takes all the parameters into consideration. http://www.compumotor.com/scripts/su...s.asp#SIZINGCD
Look for "sizing and selection tools".

As far as speed goes, rapids are not the only thing to consider. Any time an axis changes speed or direction, it has to accelerate or decelerate. Also, tools need to be run at a certain cutting rate, and if your axes can't move fast enough when cutting, you will have to slow you router speed greatly to prevent burning.