[JeffsInventions]

I have a g0704. I recently picked up a DMM Tech 3 axis 400 W AC servo kit to convert it to CNC.

Unfortunately, before I got a chance to install it, the motor died. It seems like I'm not alone in having a dead g0704 motor. I thought I would take the opportunity to add control to the spindle of the mill. Fortunately, the breakout board that came with the kit has spindle control (see page 7 of the manual).

My question is which motor and drive folks recommend. On Hoss's website, he recommended a GS2-11P0 1 HP 115VAC drive and a MTR-001-3BD36 1 HP 3600 RPM 3 phase motor. As he points out thought, the motor is huge and relatively low RPM.

Is there a motor-drive combination that would deliver as good or better performance as the g0704 stock 1 HP motor for less than $500 (preferably substantially less than $500)?

Thanks.

[JeffsInventions]

I've done some more research and found that the MTR-001-3BD36 has a face diameter of about 7". I measured the space for a motor on top of the g0704 and found that the clearance between the spindle and the column could fit a motor with a face diameter no larger than 6.5".



Any suggestions on a 1 HP, 220V, 3 phase (the drive takes in 115V 1 phase and puts out 220V 3 phase) with a face diameter less than 6.5" (preferably substantially less so that I can put a cover on the spindle)?

Thanks.

[Fastest1]

Why not use the treadmill motor as Hoss does?

[hoss2006]

Might think about one of the 3.8hp treadmill motors with a kbmm-225.
I just ordered a 3.8 on ebay to test out.
Hoss

[mrcodewiz]

The 3.8s work great. Much better than the 2.5s. I have been running one for quite a while with no problems. I don't have the PDB on in the photo but it fits fine.

http://i457.photobucket.com/albums/q...4/6275c771.jpg

[JeffsInventions]

Thanks for the suggestions. Your motor mount turned out well, mrcodewiz.

I picked up a 3.8 HP treadmill motor from ebay. My concern with the KBMM-225 is that it is only rated for 2 HP at 220V. Is there a way to be able to tap into the extra 1.8 HP? I know it would mean a big amp draw (3.8 HP * 750 W / HP / 220 V = 13 A)...

[TiagoSantos]

"In addition, the rating of the control can be extended to 11/2 Hp at 115V and 3 Hp at 230V by the use of KB’s auxiliary heatsink."

The extra 0.8HP I think you'd be out of luck for

[mrcodewiz]

I am using a KBMM125 since that was what I bought to go with the 2.5HP motor I used to have. Even so, with the 1.5 HP resistor and heatsink it seems to be way more than adequate.

If you want, I can upload the Alibre files for the bracket that goes around the motor and the uprights. Mine is sort of hacky since I just tweaked the ones I originally made for the 2.5HP motor but maybe the measurements would be helpful.

[TiagoSantos]

Not that I've researched that much, but none of the eBay ads I found had an rpm spec for these 3.8hp motors.. Any ideas?

[mrcodewiz]

It's slower than the 2.5s. I want to say about 5k RPM but since I have the kbmm125, I'm only passing about 110 volts I believe.

[mrcodewiz]

Here are my Alibre files

[JeffsInventions]

I ended up with a KBWT-112 given that the treadmill motor only goes up to 130V. Continuous 1.5 HP with an intermittent 2.5 HP isn't bad.

mrcodewiz, thanks for the drawings. It's nice not having to start from scratch on figuring out how to mount the motor.

[fretsman]

mrcodewiz, any chance these files can be converted to Solidworks type files?

Possibly IGS or STL?

Thanks for looking-
Dave

[mrcodewiz]

I have never exported from Alibre to STL so hopefully these work

[fretsman]

Thank you sir, they look like they came through just fine-

Dave

[wizard]

I have a g0704. I recently picked up a DMM Tech 3 axis 400 W AC servo kit to convert it to CNC.

Unfortunately, before I got a chance to install it, the motor died. It seems like I'm not alone in having a dead g0704 motor. I thought I would take the opportunity to add control to the spindle of the mill. Fortunately, the breakout board that came with the kit has spindle control (see page 7 of the manual).

The failure rate for these motors is pretty massive. You almost have to plan on an update right off the bat.

My question is which motor and drive folks recommend. On Hoss's website, he recommended a GS2-11P0 1 HP 115VAC drive

We use a bunch of these drives at work with almost zero problems. They are a very good value.

and a MTR-001-3BD36 1 HP 3600 RPM 3 phase motor. As he points out thought, the motor is huge and relatively low RPM.

There are other frame sizes you could look into. Don't forget that metric frame motors are fairly easy to get these days too.

Is there a motor-drive combination that would deliver as good or better performance as the g0704 stock 1 HP motor for less than $500 (preferably substantially less than $500)?

Thanks.

DC motors and drives are relatively cheap but frankly I'd prefer an AC drive. Mainly because you don't have to deal with brushes and the price is more of a toss up these days. Your first goal should be a motor that mechanically fits on the mill and then buy a controller suitable for that motor.

Frankly I'm not convinced that the motors on these Chinese machines are actually capable of producing their rated horse power for any period of time. It ought to be fairly straight forward to improve on the motor as almost anything you buy domestically will be of sounder construction and far better quality. Even used hardware will be better.

Baldor has a nice motor size chart here: http://www.baldor.com/pdf/501_Catalog/BackCover.pdf

[Fastest1]

codewiz, thanks for the file. I had never opened an STL in CamBam. That was cool.

[jeazor]

I also am looking to upgrade my motor fo rmy G0704. I would like the most HP and RPM for my 120V wiring where my mill is located. What motor and board options do I have. Thanks