Hi!

Recently, I've got envolved into CNC Router project ... Everything goes fine, but the problem is the selection of steppers ... The question is how can I measure the required torque for my motors to turn the lead screws?

I'd preffer to work with bipolars. Also, one more thing is where can I buy required motors with nice prices? Meaning, surplus shops are not really common in Finland, so, maybe anyone could give me an advice on that.

PS!

What are the reasonable ranges in prices for bipolars with required torque? (new & used)

Thanx!

 

Are you familiar with this CNC forum.

Mike.

 

Buy the biggest stepper motors you can afford. You might want to upgrade the machine in the future and this will save you buying another set of steppers.

To give you an idea on price I paid around 10 euros (£6) each for some rather nice Sonceboz 185 (ish) Oz In bipolar stepper motors from someone who had hundreds of them but obviously didn't know how good they were.

 

Yep, just got an idea from there ... Found two xerox machines being sold on local ebay-like thing. I'll check their motors ...


Well, I'd love to ... But it's really problematic (budget ... budget ... budget ...) ... Actually, I just want those guys with CNC project to be happy and see some drawings, done by their mill ... Should I be doing it for my own interest, I'd follow your advice.

Well, in Finland, 10EUR means a poor man's DC motor ... (even used).

 

Even for the UK the money I paid for the motor was a lot less than it was worth. The seller had a load of brand new surplus motors in and was just selling them at 10 euros to get rid of them.

Suprisingly they weren't that popular - if he had listed less of them and charged 3 times the price I'm sure they would have been snapped up.

185 oz in motors will happily drive a piece of 10mm threaded rod with a 10kg payload at a relatively slow speed and will crush your fingers against the side of the machine if you don't keep an eye on what you're doing.

At slow speed my machine can easily rip itself apart.

 

I've got three of these motors, free. They were going to throw away some huge, old IBM printers when they upgraded to laser. Always thought it would be cool to build a CNC router to etch and drill PCBs, but figured these would be a little bigger then needed. I'm more interested in a milling machine. I know my construction skills are much too weak to pull off something that needs to be precise.

I spent a lot of time on the CNCZONE forum, they build these things, like we do circuit boards. It's amazing what they come up with. Definately the place to go for anything CNC.

Attached Images

	Stepper01.jpg (362.4 KB, 9 views)
	Stepper02.jpg (358.4 KB, 8 views)
	Stepper03.jpg (335.4 KB, 7 views)
	Stepper04.jpg (357.3 KB, 8 views)
	Stepper05.jpg (179.6 KB, 10 views)

 

A few thoughts:

A. If you have enough done so that you can actually turn the lead screws in a situation that represents actual use - you might put together a test fixture consisting of a wheel with string where a pull on the string would result in rotation of the screw. Known weights, a fish scale or similar crude measuring might give an approximation. A torque wrench could be useful but low torque models are not common items in most toolboxes.

B. You might just take a guess or use what you can afford - but leave room for a timing belt or gear reduction drive to increase torque. You'll sacrifice speed but once you have a sense of what works you can retrofit more powerful motors in the future.

__________________
stevez

 

Well, I hope that I will find smth usable in those xeroxes, which I'm going to buy today perhaps (if the price will fit the sanity). I have one bipolar stepper, which I've got for free, but it's not enough, I need two more. That one I'm currently using for drive building/testing purposes. Hopefully, it will do some job inside our CNC as well, but however I've got a drive ready/tested.

 

Was it something like this you had in mind??

http://www.instructables.com/id/Easy...lling-Machine/

__________________
Simplicity rules

Good enought - its perfect ??

2 Gig of free online backup space

Are you a Chemist?

 

almost 100%, except that I don't like his water-pipe chasis ... Well, it's cool, simplicity rulez, of cause, but ... We need smth more ... But the idea is 100% the same.

 

Well change the chassie to some thing else like square pipeing or something eles like it.

__________________
Simplicity rules

Good enought - its perfect ??

2 Gig of free online backup space

Are you a Chemist?

 

If you're going to do it, build a big one lol. Heres the one I'm currently working on. I was just about to go out and build a nice 1Kw linear power supply for it (well 6 power supplies in one case) and I had a phonecall offering me more work so there goes the next couple of days lmao.

 

Well, looks cool ... But, we've got a small problem ... we live in Finland, so, it's not that easy to get the "REAL" motors ... Getting from other countries is also complicated due to the weight of those motors ... So, trying to do our best ...