# Motor for PM-45 Hand Crank?



## Ray C (Dec 13, 2012)

All,

Can someone recommend a motor to replace the manual hand-crank on a PM-45 mill? BTW: Not interested in converting to CNC -just adding this as a convenience. 


Thanks

Ray

EDIT:  BTW: I'm talking about the head/column crank -not the table cranks.


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## GaryK (Dec 13, 2012)

Ray C said:


> All,
> 
> Can someone recommend a motor to replace the manual hand-crank on a PM-45 mill? BTW: Not interested in converting to CNC -just adding this as a convenience.
> 
> ...



Look for a gear head motor. With a direct connect that's the only way you can get the torque required not to mention the slower speed. Find something with the RPM you want and then worry about torque.
To find the torque you need, use a torque wrench to see how much is required to crank it up, and I would then double it just to be safe. I have a PM-45M on order so I might be interested in doing the same thing.

Here's a place that has some. This Looks like it can do the job. Check the torque on your machine though.

Gary


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## sanddan (Dec 13, 2012)

I added a gear motor to my mill using a 1/4 hp motor at I think 170 rpm. I used timing sprockets and belt to connect the motor to the crank shaft and a DC motor control card mounted in a box to the back of the column. I also use 2 gas springs to counter balance the head. At 70 in-lbs torque it will move the head without the springs but you get better control with them. The controller has adjustable speed but for some reason mine isn't working correctly.







200 to 250 RPM would be about right using the springs and having the speed adjust. For large movements use top speed and for fine movements you could slow it down. It is way better than cranking that handle.


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## jgedde (Dec 13, 2012)

What do you mean "better control" with the gas springs?  Can you elaborate?  I've been wondering if I should add them.

I'm currently making a new Z axis gib for my PM-45 (the fit of the original isn't great) from G2 Pearlitic Dura-Bar cast iron.  My mill has always suffered from some amount of stick-slip and droop when trying to use the Z axis crank as a replacement for the knee.  

What are the pertinent specs on the gas springs you used?

Thanks,
John


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## sanddan (Dec 13, 2012)

John,

Without springs the motor could move the head but seemed to work harder going up than down which makes sense. With one spring the motor runs up and down similarly but going down will tend to coast somewhat. This is only an issue when trying to move the head a small distance. With 2 springs, the up and down movement is the same and the head stops as soon as the motor switch is stopped. The springs are 100 lbs each and are SPD p/n GSNI-3610-100. I made two brackets to mount the spring and installed it at the full head height so it matched the springs full stroke. The "stick-slip" you refer to, was that when going down? Mine did that until adding the second spring.

Dan


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## bvd1940 (Dec 14, 2012)

Ray C said:


> All,
> 
> Can someone recommend a motor to replace the manual hand-crank on a PM-45 mill? BTW: Not interested in converting to CNC -just adding this as a convenience.
> 
> ...


:thinking:
Find a battery drill or a AC drill that is cheap, make a permanent mount to fit around the stub in the column wire in a two way switch and mount in a convenient place & your good to go.:thinking:
Battery drills are a dime a dozen with no battery, power supplys are easy and cheap to make or just get one off Fleabay)


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## outsider347 (May 14, 2013)

bvd1940

Do you use the the drill motor alone, or with the planetary gear reduction?
tks


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## bvd1940 (May 14, 2013)

You could use a low geared bat. drill complete if you want, also if you wanted faster or slower you could add timing pulley or sprockets & chain.
Ifin I was doing it I would just make a bracket with a saddle and straps for the drill, a power supply & a 2 way switch.


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## gotmax59 (May 15, 2013)

I just put one on my pm45. I used a wheel chair motor on 12 volts, with a 10 amp cheap H F battery charger for a battery. I mounted the charger on the side of the stand in the back. I used timing pulleys and a belt. It works very well . I will try to get some time and post some pics. I have about 160.00 in the hole set up.


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## gotmax59 (May 19, 2013)




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## gotmax59 (May 20, 2013)

That is the setup i did on my pm-45. I got the wheelchair motor from e-bay for 50.00, its a 24 volt motor running on 12 volts and it runs about 100 RPM. I put a switch box on the front of the the mill to turn the charger on and off and a momentary three way switch for the power up & down. I fabicated the mount from 3/16 steel. I got the timming belt and pulleys from mcmaster carr. I have had it on the machine for about a month and it works great.


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## skeeter355 (May 23, 2013)

Gotmax59

Nice setup. Can you give me some more information on which wheelchair motor you ordered and also the parts you ordered from mcmaster, HF and the control box? 

Thanks Skeeter


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## gotmax59 (May 28, 2013)

The charger i used was a #66738 H F on sale for 34.99 and i'm running it on the 55 amp start side. The wheel chair motor is a 24 volt but you can run it 12 volts, that way it runs slower. I will get you a number on the motor. I looked  on e-bay but i did not see any like the one i used. The timing pulley numbers are. 6495K16 for two and the belt was 6484K111 ( 13.5 O C ). As for the control box i used a steel power box from home depot and made a cover for it and the two switches. One switch turns on the charger and other is a three way momentary for the up and down. I also put a power on light in the circuit so i would not forget to turn the charger off. I got the switches form NAPA. Hope this helps.


                                                The motor is a Permobil 313934-99-1


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