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Author Topic: I need HELP !!  (Read 3396 times)

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Re: I need HELP !!
« Reply #10 on: December 22, 2019, 12:40:19 PM »
This is the instructions for the BOB.

I don't have the info anymore about the purchase of the motors
Re: I need HELP !!
« Reply #11 on: December 22, 2019, 01:07:07 PM »
Re: I need HELP !!
« Reply #12 on: December 22, 2019, 02:36:48 PM »
Hi,
those steppers have 3.8mH inductance, its too high for reliable operation at speed, look for steppers with half, or less if poss,
inductance.

Craig
'I enjoy sex at 73.....I live at 71 so its not too far to walk.'
Re: I need HELP !!
« Reply #13 on: December 22, 2019, 05:13:12 PM »
Do you have a suggestion for motors that are similar but fit the need on inductance.
Re: I need HELP !!
« Reply #14 on: December 22, 2019, 05:36:05 PM »
Hi,
there are many manufacturers most of whom will have very similar steppers....all you have to do is select the low
inductance ones.

Typically low inductance steppers have a high current rating for the torque they produce because they use fewer turns but a larger diameter wire.
This tends to result in high current but comensurately low inductance.

First time buyers look for the highest holding torque but overlook inductance, manufacturers know this and produce high torque motors
but have high inductance and consequently lose steps or stall above a few hundred rpm.

Its common to have from one manufacturer a 570 oz.in stepper say, and a 450 oz.in one say, both the same size. The stronger one is better right?
Well maybe not...the lower torque unit has low inductance and will still be producing useful torque at 1000 rpm whereas the high torque unit
will have stalled at 400-500 rpm.

The main way to counteract the adverse effects of inductance is to have the highest possible voltage drivers and power supply. At the current time the
highest voltage drivers readily available are 80V. I would recommend them. You need to match it to an 80V power supply, a transformer type is
preferred over cheaper switch mode supplies.

Craig
'I enjoy sex at 73.....I live at 71 so its not too far to walk.'
Re: I need HELP !!
« Reply #15 on: December 22, 2019, 05:42:32 PM »
Hi,
this is an example:

http://www.leadshine.com/productdetail.aspx?type=products&category=stepper-products&producttype=stepper-motors&series=CM&model=D57CM31

439 oz.in at 6A but only 1.18mH. This will produce good torque right out to 1000 rpm or higher.

You might look at Leadshine's AM882 driver while your'e there, 80V and up to 8.2A

Craig
'I enjoy sex at 73.....I live at 71 so its not too far to walk.'
Re: I need HELP !!
« Reply #16 on: December 22, 2019, 10:20:41 PM »
I finally got it working.  I went from 1/2 step to 1/8 step and slowed down the speed to 500. No more issues !!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Offline RICH

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Re: I need HELP !!
« Reply #17 on: December 23, 2019, 06:37:30 AM »
Happy you got it working. :)

If as is, the machine provides the quality of machining for whatever work you will do with it, then that is what matters.

For a test do a simple square and triangle with the sides equal to 0.7 mm in length running at F500 and see what happens.

RICH