Replacing My Ac Motor With A 2.25 Hp 90vdc

Johnwright

Johnwright

Wannabe machinist
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image.jpg Ok, after trolling several Facebook (for sale or free) sites I have acquired 2 2.25 HP DC motors from treadmills to replace the AC motor on my Jet 9X20 lathe. I collected the wiring, controller boards, etc. from two treadmills but really like the idea of a stand alone controller that can (hopefully) vary the spindle speed and I can wire to have capability to reverse it as well. One of the motors (a Johnson brand) is considerably larger than the other, so in my mind it will be a more robust unit than the other. (See pics) my questions are: what controller would be best for my intended purposes, and what pulley system (either purchased or turned) would be best to get the horsepower to my lathe? I sorta like the idea of a linked belt system (like the Fenner system) but don't want to have a slipping problem. Can these belt systems be doubled up..kinda side by side..and are the pulley systems flat with a guide on the sides or do they use a v-belt type pulley? I know, a lot of questions but I'm pretty new to this machining game.
 
MC60 Controllers are cheap and common, excellent choice for running the 2.25hp motors.
commercially made pulleys are available, turning one may be more fun though!
a link belt is a fine idea, but you will have slippage issues in reverse as the link belt is most effective in the forward bias.
with some forethought, a double or triple gang pulley could be constructed to eliminate slippage in forward and decrease slippage in reverse.

slippage is not necessarily your enemy, especially in a ut-oh moment:eek:-

another consideration would be a timing belt arrangement, forward and reverse would have the same effective drive-
the pulleys are relatively cheap as are the belting- but engeneering of the drive itself would be the hurdle and a crash could be a little more serious.

a decision on your part as to which style to use would have to be made, but all things are possible :D
 
what about the pulley unwinding in reverse, I found a I think grainger controller at a garage sale that works perfect has reverse and can start where I left it no soft start. I did have mine fly off on quick reverse
 
the shaft is either keyed or tapered and the pulley is retained with a locknut.
loosening is a possibility, but if you were to add a secondary locknut the problem is minimized
 
Thanks for replying U-Dr.
Can you help me determine the approximate diameter the motor pulley should be, if used with the existing driven pulley (the one with the clutch attached). (I do think that the cog, or timing type belt is a better alternative, but I know that I can't fabricate one and haven't researched what sizes are available) Not being an engineer, I don't know what RPM range that the DC motor would be happiest when turning from extremely slow speeds up to a maximum of about 2000 RPM or so ( thinking that most of my turning is usually at 200-600 RPM). I would think that there would be an ideal range, but then, that's why I got to the pros like you! Thanks in advance.
 
Yeah, I have taken in consideration the possibility of the pulley loosening, so I ordered a LH 1/2"-13 tap. It seems to be close enough to the existing thread size, and I have already fabricated a nut for it out of round stick. (I probably just need to get some hex stock or somehow give it some flat sides to be able to tighten it up)
 
Johnwright said:
Thanks for replying U-Dr.
Can you help me determine the approximate diameter the motor pulley should be, if used with the existing driven pulley (the one with the clutch attached). (I do think that the cog, or timing type belt is a better alternative, but I know that I can't fabricate one and haven't researched what sizes are available) Not being an engineer, I don't know what RPM range that the DC motor would be happiest when turning from extremely slow speeds up to a maximum of about 2000 RPM or so ( thinking that most of my turning is usually at 200-600 RPM). I would think that there would be an ideal range, but then, that's why I got to the pros like you! Thanks in advance.
Click to expand...


Hi John
the pulley arrangement should mimic a normal drive system. with a small motor pulley and a larger driven pulley.
although the dc motor will have a greater operational envelope, you don't want to overspeed the lathe in a near 1:1 drive ratio.
you should measure the largest spindle pulley then divide that size by approximately 3 or 4 for the drive pulley
the 4:1 running slower than the 3:1
obviously you could go larger or smaller on the drive pulley.
a word of caution as the drive pulley increases in size, the effective spindle speed will increase
you don't want a 4" chuck spinning at 3000 rpm, unintentionally.

the dc motor is happy under a lot of conditions thanks to the controller

200-600 rpms is a good range to plan for for spindle speed, the motor will cover all ranges in between and more.

fabricating cog pulleys can be done, but may prove to be a challenge for a beginner.
but if you have the tooling and the will- Nothing is impossible!!!
 
Your locknut could have a set screw to lock it to the shaft. Let alone the pulley should have set screws in it. I think they used a threaded pulley , when reversed it would unscrew quickly .
 
Are you sure the motor is 90vDC? If so it might be hard to find a controller for it. Most of the cheaper controllers take AC mains in, rectify it do DC and then switch it to create a PWM signal. This means that the voltage is in the order of 150V if your mains is 110v.

A system that provides 90v is going to need a very beefy transformer or more expensive electronics.

Sent from my GT-I9505 using Tapatalk
 
the MC60 controller is common for treadmill motors as OEM equipment for the treadmill.
they are good up to 2.5 hp on 115v 60hz
 
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