Re: [CAD_CAM_EDM_DRO] Couplings

as andrew mentioned, it's probably a good idea to get a flexible
zero-backlash coupling. we prefer the helical type or the type with the
wavy spring in between both halves. either way, the point is to allow
you to have some error in your positioning of the motor/shaft.

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Andrew Werby wrote:

>
> "Alfredo Sola" alfredo@... <mailto:alfredo%40sola.es> alfredosola
> wrote: Good day Johann et
> al, Following your advice on couplings, I found this. It's Chinese but
> looks pretty decent:
> <http://cgi.ebay.de/3x-Kupplung-Drehstarre-fuer-Schrittmotor-1-4-NEU_W0QQitemZ160382401978QQcmdZViewItemQQptZMotoren_Getriebe?hash=item2557893dba#ht_3281wt_912
> <http://cgi.ebay.de/3x-Kupplung-Drehstarre-fuer-Schrittmotor-1-4-NEU_W0QQitemZ160382401978QQcmdZViewItemQQptZMotoren_Getriebe?hash=item2557893dba#ht_3281wt_912>>
>
> Also the price can't be beaten at 9,90 euros for 3 units! what do you
> think?
>
> Hi Alfredo;
>
> If those are meant to couple a motor to a leadscrew, I don't think much
> of them. Unless your alignment is absolutely perfect, a solid coupling
> like that can break the end off your motor, or the stem off your
> leadscrew. What you want for a situation like that is some kind of
> flexible coupling, which will allow for some imprecision in the
> positioning of the two shafts being joined. There are several basic
> designs for this sort of thing; such as the "Lovejoy" type, which has a
> pronged head for each shaft and a rubber "spider" that fits in between
> them, or one that has a helical slot cut in the middle, which acts like
> a spring, or one that has metal ends but a solid rubber center portion.
> The Taig mills I sell have metal cylinders on the end of the motors and
> leadscrews, which are bored with four facing holes with stiff nylon
> tubes making the connection. Any of these solutions would be better
> than what you're looking at on Ebay.
>
> Also, the simple set-screw attachment will tend to give you problems
> over time. A better design is the clamp-type connection, which uses a
> screw to compress the split end of the coupling over the shaft. This is
> less likely to loosen, and if it does, it won't make a gouge in your
> shaft that makes the coupling very difficult to remove. Yes, you can
> save some money going with those cheap solid couplings, but you'd be
> setting yourself up for losing a lot more down the line, not to mention
> the frustration factor of ruining parts and having to tear your machine
> apart to repair it and wait for parts to arrive before you can get back
> to work. I'm not sure who sells couplings in Europe, but I'm sure you
> can find some like this:
>
> http://www.anaheimautomation.com/products/coupling/flexible-coupling.php?tID=114&pt=t&cID=32
> <http://www.anaheimautomation.com/products/coupling/flexible-coupling.php?tID=114&pt=t&cID=32>
>
> Good luck;
>
> Andrew Werby
> www.computersculpture.com
>
>
>
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