PDA

View Full Version : bipolar series versus parallel wiring



deft
04-01-2004, 09:29 AM
Hello-

What are the trade offs between wiring a bipolar stepper motor series or parallel? Reason I ask is that I've noticed that most motors over 200 oz/in are greater than 3 amps. I'd like to find the stongest motors that work with the xylotex driver board and it's rated at 2.5 amp max. if the motors are wired series then (from my limited understanding) the necessary amps is divided in half. I'm assuming there is a tradeoff here somewhere I just haven't seen it described.

thanks in advance

deft

ger21
04-01-2004, 06:06 PM
I've got some PacSci 253 oz-in motors for my Xylotex. I've ran them, but I don't have my router built yet. They are rated 2.3a series. The trade off is parallel wiring will give you more top speed (actually more torque at high speeds, which translates to higher top speed). Series will still give you full torque at low speeds, but you won't be able to go as fast.

deft
04-01-2004, 06:15 PM
ahh... I figured there was a trade off somewhere.
Couldn't one simply use a lead/ball screw with fewer turns per inch to to get a relatively high feed rate while keeping one's motor in the better part of its torque band?

what is the intended size of your router? also material to be cut?

I'm thinking of a router about 18-24" y and 24-36" x, cutting wood, mdf, plastic, possibly some aluminum...

ger21
04-01-2004, 07:09 PM
Couldn't one simply use a lead/ball screw with fewer turns per inch to to get a relatively high feed rate while keeping one's motor in the better part of its torque band?

That's what I'm going to do. I've got 1/2-8 2-start acme leadscrews (4 turns per inch). But doing this involves another tradeoff. You need more torque to move a given load. But, the higher lead screws are more efficient, so you might get a little bit back.

Another option would be to build the EAS boards instead of the Xylotex. http://www.embeddedtronics.com/
These can handle up to 55V, which will raise your top speed. But then you'll spend more on the power supply. I'm assuming you're looking at the Xylotex for it's bang for the buck.

My router will be about 30"(y) x 48"(x). These are useable cutting area. The actual machine is more like 40x60. I'll be cutting wood most of the time. I've got a new PorterCable 2-1/4hp router for it.

ger21
04-01-2004, 07:11 PM
I've seen a lot of guys here and elswhere using Xylotex boards and 100-150oz motors getting anywhere from 30-60ipm rapids. I'm hoping for at least 80ipm rapids, And I'd like to cut at least 50 or 60ipm. Oh yeah, I have 2 of those motors on my X-axis, so 500-oz-in to move the gantry. I've got a Xylotex 3-axis + single axis board.

deft
04-01-2004, 11:17 PM
You are right about the xylotex=cheap thinking.

From what i've read the xylotex seem to be the best bang for the buck.

Iv'e been bouncing around between building the frame out of steel or aluminum,
and have been trying to factor in the cost versus mass (of a moving gantry) of steel versus aluminum
obviously I want to minimize cost but I want maximal performance.
I was considering 2 x axis motors but I was unsure about the added complexity, in terms of getting the machine square
and in locating the lead screws (design wise)

it's good to know that someone else is thinking in a similar way...


deft