Motor Coupler's

[SSfab]

Just wondering if you absolutley need those $16-$20 motor couplers? I seen on hoss's site, it appears he just made his own. Do i NEED them?

[Oldmanandhistoy]

Hi,

Would depend on your application but could be cheaper than having to replace stepper motors due to damaged bearings or shaft.

Do a search for more info here on the zone for more details

John

[escott76]

They make up for errors in alignment while allowing the motor to spin without excessive friction. Unless you can be sure that :
a) motor and driven shaft are perfectly parallel.
b) motor and shaft are aligned about the center
c) whatever you use to couple fits both shafts without slop and it's bores are aligned as above
you will really want to use a coupler.
Or you could waste a bunch of time "making your own", having problems which you can't be sure might be the fault of the couplers, or might be something else. Sometimes $20 (or $60 for three of em) is cheap compared to the headache and frustration they save.

[HimyKabibble]

Originally Posted by SSfab Just wondering if you absolutley need those $16-$20 motor couplers? I seen on hoss's site, it appears he just made his own. Do i NEED them?

If you're going to direct-couple the motors to any other shaft, you NEED them. If you don't, and you don't get the shafts PERFECTLY aligned, you will eventually break one shaft or the other.

You can make your own Old-style couplings very easily, using aluminum round stock, and a slab of 1/2" UHMW. Just mill a 1/4" wide by 1/4" deep slot on each side of the UHMW, with the slots 90 degrees to each other, then mill the round stock with a single 1/4" wide by 1/4" high "rib" across one face. Make the rib a snug sliding fit in the slots in the UHMW. Drill the round stock down the middle for the shafts, and drill and tap for a set screw. I made a set years ago, and they were zero backlash, and worked flawlessly. Making them larger diameter (mine were 1-1/2") makes the dimension less fussy.

Regards,
Ray L.

[hoss2006]

Well, it's been nearly 3 years with the solid couplers and no damaged bearings or broken shafts
Simple to make, dirt cheap and zero backlash.
I wasn't worried about my skills to make sure everything was parallel but the
hobbyist might want to go with the flexible couplers instead.
One of the reasons I give a link on my website.
Keling sells a couple of nice looking coupler types.
Hoss

[SSfab]

Enough said. I will purchase some. I was unaware of the reasons for using them.

Good info as usual.

Thanks, Scott

[HimyKabibble]

Originally Posted by hoss2006 Well, it's been nearly 3 years with the solid couplers and no damaged bearings or broken shafts Simple to make, dirt cheap and zero backlash. I wasn't worried about my skills to make sure everything was parallel but the hobbyist might want to go with the flexible couplers instead. One of the reasons I give a link on my website. Keling sells a couple of nice looking coupler types. Hoss

Hoss,

Three years? That's just about how long mine lasted before the first motor shaft snapped. You may have just jinxed yourself! :-)
Solid couplings will work, *if* everything is lined up really well. But that is hard to achieve (and even harder to prove you've achieved it), and the couplings I described are cheap and easy to make. Cheap insurance, if you ask me.

Regards,
Ray L.

[steve323]

A cheaper alternative is the Lovejoy connectors from Enco at about $8 for 2 hubs and a spider. This option also allows you to easily join 1/4" stepper motor shafts with 3/8" or 1/2" screws.

Steve

[Crevice Reamer]

Originally Posted by steve323 A cheaper alternative is the Lovejoy connectors from Enco at about $8 for 2 hubs and a spider. This option also allows you to easily join 1/4" stepper motor shafts with 3/8" or 1/2" screws. Steve

But Lovejoy types may not start out Zero backlash, and will add backlash as the spiders wear. Helical couplings are the best of both worlds: Solid, so zero backlash, and yet flexible. Flexible couplings still need to be REASONABLY close to alignment though.

CR.

[SSfab]

I don't like the whole nylon/plastic spider idea, simply because it will wear, thus become a headache.

[HimyKabibble]

Originally Posted by SSfab I don't like the whole nylon/plastic spider idea, simply because it will wear, thus become a headache.

Obviously you've never tried it. I used mine for years, and they are backlash-free to this day. It's a tight sliding fit, using essentially self-lubricating plastic on a smoth aluminum surface. There is no measurable wear. And they will tolerate significant misalignment with near zero stress on the shafts.

Regards,
Ray L.

[Al_The_Man]

One of the oldest and most efficient (zero backlash) is the Oldham coupling http://www.mechanisms101.com/oldham.shtml
They start at about $8 in the Misumi catalogue.
I have found that applications that use aluminum Helical with in any kind of medium/high torque servo, they usually end up fracturing due to metal fatigue, and end up putting on a Stainless version.
Al.