# Dual Shaft Nema 34 Coolant Protection



## TomS (Jul 29, 2015)

Anyone have any experience or tips on sealing the outboard shaft on a Nema 34 stepper motor?  As delivered the outboard bearing is visible and open to coolant and swarf contamination.  I've measured the motor end cap bore at 28 mm and the shaft is 14 mm.  I was thinking of using a lip seal but can't tell if the bore is machined or is "as cast" so I don't know if the bore is concentric to the shaft.  I'm building a coolant shield but I'm not comfortable that it will provide enough protection given the anticipated volume of coolant and swarf. 

Thanks,


Tom S


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## JimDawson (Jul 30, 2015)

I don't know if the hole is concentric, but it might be worth a try.  I'm guessing it's pretty close.  Worst case is it doesn't work and you're out about $5 for a seal.

You could build a cap that fits over the shaft and tight to the housing.  Attach with screws or some epoxy.


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## TomS (Jul 30, 2015)

JimDawson said:


> I don't know if the hole is concentric, but it might be worth a try.  I'm guessing it's pretty close.  Worst case is it doesn't work and you're out about $5 for a seal.
> 
> You could build a cap that fits over the shaft and tight to the housing.  Attach with screws or some epoxy.



Thanks Jim.  I'll call around to the local bearing houses and see if they can get me a couple of 14 x 28 mm seals.

I did some more web searching and found a company that makes plastic Nema motor covers.  A little pricey at $21 each but if the seals don't work out this may be an alternative.  They are also IP rated.

BTW - the company name is DY Engineering.  They sell direct and also thru CNC4PC.

Tom S


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## jbolt (Jul 30, 2015)

FYI - based on my year and a half of using flood coolant I would setup your shields to keep coolant completely off the motors. Coolant is very tenacious at getting into spaces you would not think possible and it is very good at defeating a lot of adhesives and sealants. Removes paint and makes some plastics brittle. This may be dependent on the coolant. I started with Premier 600 Synthetic but switched to Rustlik 50/50 due to the other being irritating to my respiratory system. Coolant would also wick up the wires into the motor.

RTV silicone's did not hold up. Gasket sealers do well. I used Prematex "Right Stuff" gasket maker on my coolant tray and shield joints. It has held up well.

Jay


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## TomS (Jul 30, 2015)

jbolt said:


> FYI - based on my year and a half of using flood coolant I would setup your shields to keep coolant completely off the motors. Coolant is very tenacious at getting into spaces you would not think possible and it is very good at defeating a lot of adhesives and sealants. Removes paint and makes some plastics brittle. This may be dependent on the coolant. I started with Premier 600 Synthetic but switched to Rustlik 50/50 due to the other being irritating to my respiratory system. Coolant would also wick up the wires into the motor.
> 
> RTV silicone's did not hold up. Gasket sealers do well. I used Prematex "Right Stuff" gasket maker on my coolant tray and shield joints. It has held up well.
> 
> Jay



Jay - thanks for the advice.  My motor shield is a copy of yours.  It wraps around both ends of the table to cover the X axis motor and the floating bearing block on the other end.  It also extends from the front of the table to cover the Y axis motor.  The edges of the shield hang down about 7-1/2 inches.  I'll post some pictures in a day or so After I finish it up.  

You made a good choice with using Permatex Right Stuff.  I've used it on several cars I've built and will use it on my enclosure as well.  It has never failed me.

Tom S


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