[rcrabb]

I have been slacking for over a year now. I have a small home built machine with a 8" x 14" cutting area. I am currently using a FET3 board from Stepperworld controlled by Mach3. My motors are 230oz/in with 5tpi ballscrews. My top speed is about 30ipm with no load. After that I start loosing steps. I know I can increase my power supply from 12 to 24 volts. I choose not to do this because of the size of the supply needed with the current limiting resistors. If buy a Xylotex board with their 24volt supply will I see an increase in speed? What speeds have other people reached with Xylotex?

[ger21]

What are te current and voltage ratings of our motors?

There's no gaurantee, but I've read a lot of posts with claims of double the performance when switching from Stepperworld to Xylotex. The fact that you'll also be doubling the voltage makes it likely that you'll at least double your speed as well. But, if the current and/or voltage ratings of the motors are high, you may not see that big a difference.

[rcrabb]

The tag on the motors reads 4.5volt 1.5amp per phase. I am very pleased with my stepperworld board but I need more speed. I have calculated at one time I would need about a 12amp power supply if I upgrade to 24 volts with the stepperworld board. If I change to a Xylotex board I can use the 24 volt 4.2 amp supply I have in my junk pile.

[candle]

it seems you have unipolar driver, go bipolar - really...
it is not uncommon to see steppers running on very high voltage - 10-30 times of what they are rated
torque you're able to get on high speeds are directly dependand on voltages (thus current curves) that driver can produce for your stepper
30-40V drivers shouldn't be much more expensive compared to what you already have

[rcrabb]

Thank you Candle...... I will be purchasing the Xylotex board in a few days. It is a bipolar driver capable of 35 volts. The stepperworld board I have now is a unipolar driver. Thank you for the advice.

Anyone reading this thread that has a Xylotex board please post how you like the board and what speeds you can run with the board.

[project5k]

i dont know about the xylotex stuff, but if your looking for cheap powersupplies, may i suggest modified computer power supplies.. its what im going to run, and the modifications are really easy.. there are several articles on here and the net about how to do it.. im going with "AT" types cause there soo plentifull and dirt cheap, i mean cheap to the point that i got 4 this afternoon for free, well i did have to drive about 30 miles, but i was gonna go that way anyway, so it was nothing more than a stop along the way... im planning on running 7 of these in series for 35 volts at around 20 amps.. about all they will cost you is some time and a couple resistors (read the article about load biasing the 5v regulators) and the resistors are avialable at cellphoneshack (radio shack, but i cant go in there without them trying to sell me a new cell, even tho i have a treo 650 on my belt) and are something like 3 bucks a peice... way i figure it, if your at all low on funds, cant go wrong for a cheap well regulated powersupply...

one other thing, make sure about your motor wiring, i've seen some motors that just didnt wanna go bipolar... might be something to double check before you wire everything up and let out the majic smoke...

[candle]

thats real mistery to me..
no go for bipolar? it had to be operator fault

[project5k]

no actually they were really odd motors, and all the coils were wired common together, and came out as one... it was some kind of 4 phase unipolar, cause there were 5 wires, and you could get some sort of impedance reading between any 2 wires... so i just dont see how its possable to wire that one any other way than unipolar... but i know that the motor was good cause when hooked to the right driver, it would run just fine....

[candle]

oh
the 5 wire ones
one for power supply, rest for shortening to ground

[project5k]

something like that, but theres no bi operation, only uni....

[candle]

yeach, one need to cut internal connection between central taps of two windings to get them bipolar
usually they aren't worth of looking at them at first place - old, and not much of torqe

[project5k]

agreed, but in RCRABB's situation, its something to look at before just getting a new driver board... and making the move from uni to bi

[rcrabb]

I like the idea of the PC power suplies. I do have a pile of these also. But that still doesn't get me away from the big current limiting resistors. I will be ordering the Xylotex board. But please keep me posted on your power supply project.

[project5k]

can do... i have already modified 1 of the power supplies, and linking the 12v's i can get 24v @ 7a or linking the 5v's i can get 10.1v @ 20a... so so far its working well... i tried my driver board and one of my motors laying on the desk here and at 12v i got something like 375rpm before it went into cogging, and then i tried at 24v and got something like 600rpm.. now this is with just the motor and a 3lb disk i spun up on the lathe, just for inertial purposes... so i'm hoping that at 36v i can get maby 750 usable rpm, but we'll have to see what the torque is like at that fast...

[candle]

its all about how fast the current curve goes up in motor windings
faster it is, faster motor will go before loosing torque
i've seen drivers using 160V DC at reduced current (for a given motor) to a half
initial torque was lower, but torque/speed curve was linear - 30% drop on max rpm - thats somethin'!

[Den-Den]

I am using the Xylotex 269 oz motors and their board and am very happy with it so far. Not sure how fast it will go, now running 50 ipm rapids with 1/2 - 10 acme screws. It would problably go faster but I have not pushed it.

[project5k]

well thats 500rpm, how long is that travel on that screw?

[Den-Den]

The travel is 18" x 18" x 6", I would want more speed if it were larger.

[project5k]

i understand.. im in the process of building mine right now, and if things continue to go like it looks that they will my 3'x3' should be able to do something like 75 IPM

[rcrabb]

Today I have recieved my Xylotex board. WOW. Durring my initial tests I am able to get about 900 RPMs before the motors stall. This test was done with the motors uncoupled. With my Stepperworld board I was only able to get 200 RPMs. I figure I should safely get 100ipm cutting with 180ipm rapids. I'm sure alot has to do with the increase in voltage but the investment was worth it.