Stepper requirement for 4'x3' steel/alu build

[leaveme]

I'm going to build a new 4'x3' router. Base will be in steel, gantry and others will be mostly in aluminium. It will be used equally for aluminium/wood/mdf routing.

Now I need to identify the stepper requirement for the build. I found a local source of used steppers in very good shape and damn cheap. They are all Nema 34 (8 cables). The highest I found is (picture attached):

Model: Step Syn
Volt: 2.5
Current: 4.6

I would like to know whether this stepper is sufficient for my build.
Any idea about its torque profile...?

Thanks in advance.

[CarveOne]

You should be able to find some information about them on the Sanyo Denki site. Scroll down to the bottom of the page to find the list of motors and click on Nema34.

CarveOne

[leaveme]

Originally Posted by CarveOne You should be able to find some information about them on the Sanyo Denki site. Scroll down to the bottom of the page to find the list of motors and click on Nema34. CarveOne

I actually checked there before and couldn't locate anything. Seems it is a custom build.

Posted here, hoping that someone may have seen or used it. :-)
I can buy them about $30-$40 each.

[CarveOne]

The way they structure their stock number leads me to think they are 815 oz-in motors. and would be more than enough torque. They are 1.8 deqree, which is also good. Most folks use Nema23 size motors for a 4' x 3' size machine. You will need a driver that can drive 4.5 amps. Gecko G203V is a good choice. Use a 48vdc or 65vdc linear power supply.

CarveOne

[CarveOne]

Originally Posted by CarveOne You should be able to find some information about them on the Sanyo Denki site. Scroll down to the bottom of the page to find the list of motors and click on Nema34. CarveOne

8 wire motors have a lot of wiring options but most I see available now are four or six wire. DIY'ers tend to use bi-polar four wire nowadays. Lower cost to build them without all those internal wire connections.

CarveOne

[Crevice Reamer]

Avoid these! They are NOT a good bargain.

Because of the type of magnets used, round steppers lose their magnetism over time. They haven't been manufactured in so long, chances are very high that they have already lost enough power to be unreliable.

This is what I recommend:
http://crevicereamer.com/Page__57.html

This commercial router uses slightly slower motors than the above:
YouTube - IronMan CNC Router 4 Axis
CR.

[leaveme]

Originally Posted by Crevice Reamer Avoid these! They are NOT a good bargain. Because of the type of magnets used, round steppers lose their magnetism over time. They haven't been manufactured in so long, chances are very high that they have already lost enough power to be unreliable. This is what I recommend: http://crevicereamer.com/Page__57.html This commercial router uses slightly slower motors than the above: YouTube - IronMan CNC Router 4 Axis CR.

Really interesting info! I never heard that round motors loosing its magnetism by time.
Is it worth if I get them $20-25?

[Crevice Reamer]

Originally Posted by leaveme Really interesting info! I never heard that round motors loosing its magnetism by time. Is it worth if I get them $20-25?

No. If they haven't already lost most of their power, they will continue to lose it.

Do you want good performance or just to see it move once?

CR.

[CarveOne]

I have seen these warnings, but also see machines using them. Personally, I wouldn't spend my money on these older motors in unknown condition. I don't fault people for bargain hunting though. Taking a chance on them is your choice. You pay your money and roll the dice to see what you get.

CarveOne

[Crevice Reamer]

To help you with your decision:

Q.) Why do you recommend not using round steppers? A.) Round steppers use rare earth magnets, and lose their magnetization over time. Because most of these were made in the 1980’s and before, they have already lost a substantial amount of magnetization. Square steppers use permanent magnets however, and provide much higher torque than their round brethren. Mariss.

http://geckodrive.com/upload/Gecko%20FAQ.pdf

CR.

[arizonavideo]

I've taken apart about 10 steppers so far just to see how they are made and the magnets are the same in the ones I have had. The NEMA 34 and 23 both were the round kinds.

Their is a lot of difference in the motor structures so I have no doubt that the square motors are a better unit but I have not heard of de magnetizing being a big problem for all round steppers and not the square ones. Many servos can become de magnetized too but I have no seen suggestions not to buy a good looking used servo.

Either way the old round steppers are just less efficient and are more prone to resonance peaks and always have a higher inductance for the same torque so are slower than a new motor of the same power.

Less efficient steppers might make you get larger drivers and then the savings would be gone.

The little Gecko drives and some KL23H2100-50-4B 570 OZ steppers really work well and would blow away the round steppers unless you get the G203 drivers and still the smaller rotors in the KL23 will reverse a lot faster.

[CarveOne]

Originally Posted by Crevice Reamer To help you with your decision: http://geckodrive.com/upload/Gecko%20FAQ.pdf CR.

If the motors were made in the 80's and are pulled from well used salvaged equipment I would assume that what Mariss says is true. If the motors have been in storage and are never run, NIB condition it could go either way. It's still a crap-shoot situation.

In either case, the newer generation of motors are well worth the cost difference to me.

CarveOne