Thread: Mars Lathe DC motor conversion.

Wow Ewan, CBC ripped you off.

I paid $11each for my resistors and they came from Sydney. I got a 1.5 and 2 HP just in case of problems. I picked them up from the Regency Park branch.

This 2 HP motor problem is most puzzling. I tried it on two controllers (I have plenty and exactly the same issue - motor crackling and no power and then either the AC or DC fuse blows.

Hooked up the 1.5 HP motor and all is sweet - no issue. Everything works just like it should . It does whine a bit though. Might just be the fan.

So took the 2 HP motor out in the sun to try and see if any blackness was evident on the armature - couldn't really see, so I pulled it apart and everything looks OK.

I'm wondering if the motor rating is wrong and it"s actually more than 2 HP. It's a big unit.

I can't see any signs of arcing, yet you can clearly hear the motor fizzing before the fuse pops.

Really really odd situation.

I suppose the armature could be gone internally. but it seems unlikely. Looks like brand new. I will run the multimeter over it tomorrow.

Good to see you got yours going OK.

Cheers

Rob

Hi all,

I'm continually looking looking for options when it comes to using a 3 HP 220V DC motor I have. I have attached pic of it before. Anyway I have been looking for a cost effective way of running it at or close to it's rating or at least 2000W. Trouble is there is not a lot out there. I was wondering if you could use two of these:
AC110/220V Input 2A/3A/4A/5A 1000W SCR DC Motor Speed Controller Driver Adjuster | eBay

and just parallel them with some inline high powered rectifying diodes so that they will not interfere with each other. The pots could be combined using a a double gang pot.

Is this a viable alternative?

Simon

Originally Posted by Ueee

I have found in the past (the hard way) that the only way to makes sure a crimp fitting doesnt come loose is heatshrink, so thats why it is everywhere.....

Your crimps shouldn't be pulling off. Are you using good quality ratchet crimpers Ueee?

Originally Posted by simonl

Hi all,

I'm continually looking looking for options when it comes to using a 3 HP 220V DC motor I have. I have attached pic of it before. Anyway I have been looking for a cost effective way of running it at or close to it's rating or at least 2000W. Trouble is there is not a lot out there. I was wondering if you could use two of these:
AC110/220V Input 2A/3A/4A/5A 1000W SCR DC Motor Speed Controller Driver Adjuster | eBay

and just parallel them with some inline high powered rectifying diodes so that they will not interfere with each other. The pots could be combined using a a double gang pot.

Is this a viable alternative?

Simon

Hi Simon,
Personally thats not how i would do it . I don't know enough about SCR's but shouldn't you just be able to add extra's to the circuit to bring the power rating up? Thats what you do with MOSFETs and PWM circuits anyway, which brings me to what i would do (short of making a controller from scratch, whick would be my first choice, using an ATmega, just cause i know the arduino code) Get a PWM controller kit (like this 12/24VDC 20A Motor Speed Controller Kit - Jaycar Electronics), replace the MOSFETS with bigger ones (you will have to check the trigger voltages etc), and use the treadmill (i'm guessing its from a treadmill) power supply to drive it.

Originally Posted by Sterob

Your crimps shouldn't be pulling off. Are you using good quality ratchet crimpers Ueee?

Hi Sterob
I find it doesn't matter what i crimp with, so long as the hard plastic cover is on the terminal i don't get a good crimp. If you slip it off onto the wire and then crimp, the plastic is too hard to fit back on the terminal. So i just chuck the plastic and use heatshrink.

Originally Posted by simonl

Hi all,

I'm continually looking looking for options when it comes to using a 3 HP 220V DC motor I have. I have attached pic of it before. Anyway I have been looking for a cost effective way of running it at or close to it's rating or at least 2000W. Trouble is there is not a lot out there. I was wondering if you could use two of these:
AC110/220V Input 2A/3A/4A/5A 1000W SCR DC Motor Speed Controller Driver Adjuster | eBay

and just parallel them with some inline high powered rectifying diodes so that they will not interfere with each other. The pots could be combined using a a double gang pot.

Is this a viable alternative?

Simon

Hi Simon, have also ordered one of them myself, should be here in the next week or so, will be interesting to see how good they are for the price.

Well I have some good news. Mounting the 1.5 HP motor onto the cradle I made for the 2 HP motor will be dead easy.

Just requires a bit of additional metal and some arc welding.

So with a bit of luck I will be up and running tomorrow once the paint drys.

Here's an interesting observation I made about these treadmill motors. I ran the tape measure over the two I have and both have similar motor housing diameters (the larger is slightly fatter).

But here's the interesting bit - if you divide the length of the steel motor housing/barrel (exclude the alloy end /bearing holders) it works out at 40 mm length for every 0.5 HP.

So if you're not sure what HP motor you have got coz the label is missing, this might help.

So it looks like the 2 HP motor is indeed a 2 HP - and it's stuffed somewhere.

I did get it sort of running very slowly late last night and the fluro lights in the shed were flickering, so I recon there's a short in the armature somewhere.

Anyway, things are looking good at the moment.

Ewan have you seen this write up on DC motor torque/power characteristics ?

D.C. Motor Torque/Speed Curve Tutorial::nderstanding Motor Characteristics

After reading this, it was the reason I changed the motor pulley gearing to run at 60% RPM as maximum speed rather than up to 100%.

I'm not sure though quite how this works as the motor is actually running with less current/volts than it's capable of ????? And that seems a bit counter productive to me.

Cheers

Rob

Thanks for the link Rob.
I've got mine set to 3K max, but will probably bring that down a bit.
I Mounted my motor today, easy as pie. Straight replacement for the AC motor, hole centers are identical!
With the belts set to a 3-1 reduction i started her up. Min speed as set was 60rpm, max 1000rpm. Nice! The motor arcs a little when accelerating, i may turn the ramp up time up a bit. I then Changed the belts up to 3-2. Turned on, started winding up the speed and.....fzzzt fuse blew. tried again, another fuse. I put the belts back to 3-1 and tried again, all good. So i tested the load. Once running the motor is only using 2 amps....but as she accelerates she hit 14a (not sure how the multimeter fuse didn't blow) So i guess the acceleration time will have to be wound right up to 4 sec.

I also started on a pendant style holder for the switch box. Now lets see what i can use....oh yeah, look at all that steel from the treadmill frames, perfect! I am making it so it can be swung from over the headstock to over the TS.

How is the DC motor power compared to the old AC unit ?

Does it seem like 1.5 HP ?

Cheers

Rob

Short answer......not sure!
Long answer...well i only had a 1/2hp (3a max) ac motor, so i would expect to have plenty of power. I just went out (to take the bins out) and had a play. A 2" dia piece of mild, HSS tool, 200rpm, geared 6-1. Started a 1mm DOC .12mm feed, cut about 4 or 5mm then the 10a AC line fuse blew..... I think i need a bigger fuse, even though the controller is set to 150% of base power, so that should be 9a. I never blew the 10a fuse on the ac motor. I *think* i have more power, but i think i need to do some more test cuts to be sure(with a 15a fuse). The strangest thing is the IR compensation, once you take the load off the motor it over revs and then settles back down.

Hi Ewan,

Now I have a 1.5 HP motor as well, it's going to be interesting to see how my modern Chinese unit compares with your older (being very kind here) unit.

I will probably get it all running on Wednesday, once the paint drys and I silicon the fan onto the new unit.

This is all good stuff.

But then this is what tinkering with lathes is all about.

Cheers

Rob

Originally Posted by Ueee

Hi Simon,
Personally thats not how i would do it . I don't know enough about SCR's but shouldn't you just be able to add extra's to the circuit to bring the power rating up? Thats what you do with MOSFETs and PWM circuits anyway, which brings me to what i would do (short of making a controller from scratch, whick would be my first choice, using an ATmega, just cause i know the arduino code) Get a PWM controller kit (like this 12/24VDC 20A Motor Speed Controller Kit - Jaycar Electronics), replace the MOSFETS with bigger ones (you will have to check the trigger voltages etc), and use the treadmill (i'm guessing its from a treadmill) power supply to drive it.



Hi Sterob
I find it doesn't matter what i crimp with, so long as the hard plastic cover is on the terminal i don't get a good crimp. If you slip it off onto the wire and then crimp, the plastic is too hard to fit back on the terminal. So i just chuck the plastic and use heatshrink.

Hi Ewan,

The reason I scored the treadmill for free was because it was buggered. So the motor is good but power supply for motor is NBG! Anyway, I have now given up on this particular motor (actually it's on ebay now with 1 bid Yay!) because 3 HP is probably 1/2 - 1 HP too much and adds complexity due to it's current requirements. It was also rated at 220V and not 180V. I must say, the ease of control wiring, cost and setup parameters has now won me over with 3 phase and VFD. I do reserve the right to change my mind at any time on this and still acknowledge the huge benifits of DC motors!

In any case, I'll keep looking for a 2 HP DC 180 V motor. I have a 2 HP DC motor from another treadmill but unfortunately it's buggered. I think Rob's motor and mine are from the same treadmill!

Hey Auskart, Let us know how that controller goes when you get it!

Simon

Will do Simon.

Originally Posted by nearnexus

Hi Ewan,

Now I have a 1.5 HP motor as well, it's going to be interesting to see how my modern Chinese unit compares with your older (being very kind here) unit.

I will probably get it all running on Wednesday, once the paint drys and I silicon the fan onto the new unit.

This is all good stuff.

But then this is what tinkering with lathes is all about.

Cheers

Rob

Well i can tell you now.......Its bloody fantastic! I finished my control box pendant today and hooked the motor up again for another play. 15a fuse on the AC, 10a on the DC. I fiddled with the IR compensation a bit too. I ended up with the trim pot at 12 o'clock. I took a 2.2mm DOC .12mm feed/rev cut on a piece of 20mm dia MS at 500rpm with HSS...To start the motor slows then the IR kicks in and it runs at a steady speed. I took a video of the cut hoping you would be able to hear the motor load up and compensate but you can't really tell.

Pics of the pendant at its extreme positions





And a vid of it all working, except for the brake, i'm still waiting on the braking resister and a linear pot. I also need to put in longer wires to the motor and clean up all the wiring.

<a href="http://www.youtube.com/watch?v=xEXmd-OrJec" target="_blank">

Goodness me Ewan. Fantastic. My head exploded (I struggle with electronics).
Make sure you turn the drip feeders on next time though lol

Phil