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itsme
06-29-2005, 01:57 PM
Hi there,

Today I managed to wire up 2 of my steppers and I have attached one to my machine (Sieg Super X1). I machined new bearing blocks with angular contact ball bearings and I'm using a toothed belt with 1:1 ratio. My control board is a Unipolar 4-axis Xylotex unit and the motors are rated at 254ozin at 2.5A and 4.5V. I'm using the standard acme leadscrews and the motors are running at 2.1A.

According to what TurboCNC is saying, I'm getting 1500mm/min max speed at 10000Hz, without losing any steps. How does this speed compare to other desktop mills? I can take it up to 12000Hz without losing steps, but the machine seems happier at 10000. At about 14000Hz, it starts to lose steps. I haven't played too much with the acceleration yet.

I was quite relieved to actually see these motors working. The y-axis, which is the axis that is connected up, is probably the heaviest axis (ie. needs the most force) , as the gibs need to be quite tight to keep the accuracy. I reckon that the x-axis will be capable of higher speeds than the y-axis.

I now have a few questions (since I've never used any stepper motors before).

Is it normal for the stepper motors to get hot? I ran it for about 10 minutes and after this time the motors were hot, but I could still hold them with my hands without getting uncomfortable.

Is it normal for a motor to get hot when plugged in, but not being used?

How hot should the driver chips get on the board? Mine were quite hot (hotter than the motors). The board is in a PC case and has got 1 fan blowing air in and basically 2 fans sucking air out (all normal 80mm 12V PC fans). The board isn't directly in the path of either of these fans. I'm thinking about getting another PC fan tomorrow that will be directed over the driver chips.

I can't wait to finish the rest of this machine and start making some useful things - like fancy, 3D paperweights!!! The x-axis should be running by the end of tonight and the Z should hopefully be done in the next week. Once the x-axis is done, I'll start off with some simple 2D shapes. Yippee!!!

Regards
Warren

CNCgr
06-29-2005, 02:15 PM
Is it normal for the stepper motors to get hot?

Is it normal for a motor to get hot when plugged in, but not being used?
Yes, it's normal. As long as you don't exceed the current rating, they'll be ok. When a stepper isn't moving, it has holding torque, there's current running through it.


How hot should the driver chips get on the board?

You should read the chips datasheet. Most chips can handle up to 100°C. You should put heatsinks on them, they are more efficient than just a fan.

itsme
06-29-2005, 02:31 PM
Hi,

Thanks for the reply. The max temperature rating is 85 deg C. What exactly does a heatsink involve? Can I just machine some nice aluminium blocks with a...umm...heatsink, and then somehow stick it onto the chips? What can I stick the aluminium blocks on with?

Thanks
Warren

ger21
06-29-2005, 02:58 PM
You should have a fan blowing directly on the chips, or on heatsinks if you add them.

itsme
06-29-2005, 04:58 PM
Hi,

I'll get a fan first thing tomorrow morning for the driver chips. I'll try and get the biggest 12V PC fan I can find...

I now have 2 axes. It's great! All I've done so far is draw a few circles and squares with a pencil in the chuck. The only problem that I have, is that the x-axis is reversed. I'm not sure if I can reverse it using software (TurboCNC) or if I will have to change the wiring on my board.

I think I'll also add heatsinks at some stage, but not right now.

Thanks
Warren

CNCgr
06-29-2005, 05:52 PM
What exactly does a heatsink involve? Can I just machine some nice aluminium blocks with a...umm...heatsink, and then somehow stick it onto the chips? What can I stick the aluminium blocks on with?

Sure you can. I just used a U-shaped piece of aluminum. It touches the 3 chips (I used heat transfer compound) and is bolted on the PCB on both ends. If you have space you can use a fancier heatsink. You could use Pentium heatsinks from an old PC.

Not much of a photo but you'll get the point:

buscht
06-29-2005, 06:00 PM
You can reverse the motor direction in TurboCNC. I can't remember exactly how to do it, but I know it can be done.

abasir
06-29-2005, 08:36 PM
In TurboCNC port configuration, under X-Axis direction pin setup just reverse the entry (i.e. if active low, change to active high :))

itsme
06-30-2005, 02:44 AM
Hi,

I'd rather change the direction in the software, because I'm a bit nervous to tamper with the board when it is working so well.

Can anyone tell me what sort of maximum table speed they are getting? I'd just like to know how my 1500mm/min compares. What I do know is that when you only have about 180mm travel, it gets eaten up quike quickly...much more pleasing than standing there winding handles all day!

Thanks
Warren