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Help with conversion
« on: February 17, 2007, 10:10:43 PM »
 Has anyone had experience with lowcostcncretrofits?

The correspondence I've had with them seems fruitful in that their controller is a 'plug and play'....or so I've been told. Output from XP and Quantum via printer port to their printer port as an import. The controller receives from the encoders and then feeds the motors for movement.

I have a couple bumps in the road....this is what I have

The motors need be DC and with brushes...ok
The encoders need be 5 volt...ok
The X, Y axis has encoders on the motors and also on the table....Should I try to incorporate both to the controller? Would it be more repeatable or increase accuracy?

Output from the transformer is 0 volts, 26 volts, 52 volts.....the motors are 60 volt.

A special capacitor who has 100 volt and 10000uf is connected to the xyz pc boards of the old system either direct or via a Motorola 8649W microprocessor. It has been suggested that I put capacitors to 'smooth' out the motors. Where do I put them? At what value? Do they need cooling?

Anyone with electronic experience to bail me out is appreciated....anyone who has had a positive experience with lowcostcncretrofits is also appreciated. Thanks in advance!!



Offline Graham Waterworth

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Re: Help with conversion
« Reply #1 on: February 18, 2007, 03:06:26 AM »
Hi FranH,

I bought a servo system from them including there motors for a lathe project, all I can say about that system is, It dose what it says on the tin.

its been running about 8 months and not a single problem, its accurate and faster than the old stepper system.

Without engineers the world stops
Re: Help with conversion
« Reply #2 on: February 18, 2007, 06:47:17 AM »
Thanks for the info from cncretro.

 Now that I'm an EE (Hey I got 2 hours of reading under my belt), /....I think the better plan is to go to an electric motor repair shop to see if he has 10000uf 100volt capacitors...1 to each 60 volt motor...maybe a bit overkill but I wish to not stain my shorts.   ;D

Since the original equipment had the capacitor downstream from the transformer and upstream a kazillion electronics from the motors...would placement at the motor leads be a logical place?

Thanks again


Offline chad

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Re: Help with conversion
« Reply #3 on: February 19, 2007, 08:57:09 AM »

You do not want to put caps across the motor leads. That would be very bad. DC servo motors rotation is dependent on polarity, if you give it juice one way it will turn forward if you give it juice the other way it will turn backwards this is all done in the servo controller. If you put a big cap on the motor leads it could lead to an exploding cap and a fried servo drive. Most big caps like the one you are talking about are also polarization sensitive if you hook them up backwards they can explode, sometimes violently.

The cap should be after the bridge rectifier on the power supply, the smoothing that you are talking about is for the ac to dc process.

A motor repair shop is most likely only going to have ac start or run caps they won't have what you are looking for.
You need something like this http://www.mouser.com/search/ProductDetail.aspx?R=36DY103F100CB2Avirtualkey61320000virtualkey75-36DY103F100CB2A

When you measured the output of the transformer was that straight from the transformer or after rectifying (ac or dc)? If it is ac straight from the transformer then after it is rectified it will give you about 73vdc (52 V * sqrt(2) = 73.5391052 volts) and that would be just fine for your motors.

As for the encoders, you should use the ones on the motors.


« Last Edit: February 19, 2007, 09:37:23 AM by chad »