A Little Experimenting

I had a little time (but not enough to do everything I want to) to test some of my machines,to compare their performance. I pretty much knew that the Gecko stepper drives are better than most everything else in terms of ability to accelerate and perform well at high speeds. My test prove this. The Gecko G203V can produce much faster acceleration and high speed operation than the generic Chinese drives. Of course it costs twice as much and most people can get by without high acceleration rates but if you want the best machine possible you should spend the extra money on the Gecko drive. The G201X is every bit as good and a little cheaper but it is a little easier to destroy than the virtually indestructible G203V. I also determined that the best power supply voltage is about 67 volts and that 300 VA is more than adequate. This can be had with a power supply made with a 45 volt transformer.

If you really want the fastest accelerating  machine I would recommend a NEMA 23 motor instead of a NEMA 34. Unfortunately these have smaller diameter shafts and will require shaft end bearings to support the load on the drive wheel. The difference is not that great and most people would never need the increased acceleration. Another possibility is to use a Servo motor instead of a stepper which has advantages especially if you want to slave two or more machines and not have then drift out of sync but there are disadvantages as well.  Not going to go in to those here because I decided that steppers are the best for most applications. Also the NEMA 34 servo motors are pretty sluggish so a NEMA23 is recommended with a shaft end bearing.

I also figured out a very easy way to set the proper drive wheel load. I never felt good about the way I was doing it before. Getting it just right was a bitch. To set the ideal load, use a 7/8″ OD tube or dowel instead of the 1″ OD tube that is used for the machine. Place the tube where the regular tube would go and adjust the idler wheels to just contact the tube while the drive wheel is also in contact. Adjust for a slip fit. When the 1″ tube is in place it will have just the right amount of pressure from the drive wheel assuming that you use the recommended one. Three quarter inch copper plumbing tube is 7/8″ OD but a piece of 7/8″ wooden dowel is cheaper if you can find it.

I have a new stand (actually an old one that I revised) that I will be testing and will post pictures soon.

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1 Response to A Little Experimenting

  1. AZ_Kinkerer says:

    Good info!! I’m hoping to have my enclosure ready for paint sometime today, although in the afternoons, it gets to about 130f in my garage… (Not an exaggeration!!)
    Anxious to see your new/rehashed stand, as I’m still trying to decide on how I want to do mine.
    You’re timing on setting roller pressure was perfect, as I was going to email you about the method you use.
    I’ll update the Eroshare page when my box is done.

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