View Full Version : Conect 121 DC spindle motor help!

04-02-2015, 01:05 PM

I have just purchased one of these little machines with the intentions of converting it to run Mach3. The first concern is the large DC motor controlling the spindle. I don't have the control box for the lathe and I am assuming that's where the power supply was. I need to figure out a fairly low cost method of wiring up the spindle motor to a speed controller and either having an external speed control or having it work from the new BOB.

If anyone has had to do this before and has some recommendations please let me know. I haven't received the machine yet but i will have it by the weekend hopefully, can get some specs on the motor then unless someone knows exactly what it is.


04-02-2015, 01:19 PM
There's no link to anything so can't see what you mean.

04-02-2015, 01:42 PM
Hi, Eddie.

Sorry but I don't have any information on the motor yet to link.

I was hoping someone may know the model of motor and have already solved this problem.

This is the type of lathe

http://www.google.co.uk/imgres?imgurl=http://www.machsupport.com/forum/index.php%253Faction%253Ddlattach%253Btopic%253D19 342.0%253Battach%253D27558&imgrefurl=http://www.machsupport.com/forum/index.php?topic%3D19342.0&h=487&w=634&tbnid=C4kFIob_17he7M:&zoom=1&docid=EqO7YWSmR6eLwM&ei=FR_SVNPzK-uw7AbDu4CYCw&tbm=isch&ved=0CCMQMygCMAI



04-02-2015, 01:48 PM
Okay, I've just seen the model number was in your post title, It catches me out every time :stupid:

Did you read this lot ?


04-02-2015, 05:37 PM
Okay, I've just seen the model number was in your post title, It catches me out every time :stupid:

Did you read this lot ?


Yea, hood ditched the dc motor unfortunate and used servos on everything. I really want to use the dc motor and the stepper motors.

Thanks for the info tho!

04-02-2015, 11:11 PM
I bought a small Connect mill which came with a problematic DC spindle motor, it turned out to be the DC drive causing the problems. Decent DC drives were silly money so I ended up with a new 1hp 3phase compact frame motor and new old stock Siemens drive for about half what I'd been quoted for a DC drive

04-02-2015, 11:34 PM
I've looked it's not going to be cheap going down the Ac vfd route, nothing cheap in ebay anyway. Not ruling it out tho, may just take time to find a cheap setup.

I have made some progress and have found a reasonably priced kb dc controller box.


I think someone on here used a kb board but linked it to the bob. more reading required!

05-02-2015, 07:17 AM
Hi, I use exactly that controller on my Novamill for a similar motor and it works very well. HOWEVER if you are going to link it to a BoB it needs an isolating circuit as the KB controller electronics are not isolated from the mains. There has been some discussion here to which I contributed a circuit which I haven't yet tested. I will have a poke around and try to send a link.

Found it! Look for a thread called

One day soon I need to build that circuit for my own use!

05-02-2015, 08:13 AM
Thanks for the info!Was it fairly simple to.hook the controller up? If the box can be linked to the bob in future I may just go for it and deal with the bob feature later. Does the box have options to set the min and max rpm?


05-02-2015, 01:59 PM
As I said, I haven't tried it yet. It would be pretty easy to hook up, it would replace the speed control pot, but you would need to take care to respect the mains voltages on the KB controller.

The KB box certainly has max speed setting, I can't remember about min. If you go to the KB Electronics website you can download the manual which has all the details.

05-02-2015, 02:31 PM
Sorry I meant easy to hook up to the motor. I Idid see in that thread you posted that there are off the shelf options.

As long as I can set the speed accurately via the box I should b
be able to do threading etc.. I will download the manual and read it, thanks again!