My 9 x 20 Lathe Page (Grizzly G0516)

G0516 Variable speed mod (DC motor and controller)


Choosing a Controller

Basically I stumbled upon the Boston Gear Beta II while looking for DC motor controllers on eBay. There was a link to the manual on the add so I downloaded it and started digging into the details. Everything I read just reassured me that this was the controller for this project. It would accept either single phase 110 or 220 and would drive motors from 1/16th HP to 2 HP. This is a true PWM (pulse width modulated) logic controlled device. It has high and low speed pots, a current limit pot, ramp-up and ramp-down pots and it's made by a well know company (Boston Gear) and it's still sold and supported.

I had considered making my own controller but quickly decided that it wasn't worth my time and effort. I ordered the controller from 1st Bid Wins on eBay. You can look him up. He still has many of these in stock and the price is 169.00. (since that time...I have found a few for less money....but it's hit and miss....

Feel free to download the manual from the link to the left and take a look for yourself.


Choosing a motor

I set out looking for a treadmill motor like most of the people in the forums had experience using. Every time I found one there was something I just didn't like about it. I searched the web and ran upon They had many DC motors and decent prices. The motor had to be:

continuous duty, permanent magnet, reversible, 5/8" shaft at least 2 1/2" long in the 1 to 2 HP range. The fact that this motor met all those requirements was just shocking.

Keep in mind that this motor is rated at 3200 RPM. That's nearly twice the speed of the factory AC motor on the G0516.......BUT.....if you consider that the controller is only going to make 90VDC strapped for 110VAC input you'll only be able to get about 2200 RPM out of it. But that should be ok as you probably don't want to run your main pulley and timing belt at those speeds anyway. The real advantage here is the variation of speed below that of the original motor.

From looking at some engineering data on these type of motors I've concluded that running the motor from the mid range down to 25% puts you in the sweet spot for HP and torque performance anyway.


More on the Motor

The shafts on this motor are both 2.5" long so you could mount it in either direction...though you'll probably choose to mount it with the pulley on the end closest to the label. This for several reasons. 1. the motor mount is closest to this end thus providing more stability. 2. the wiring harness enters from the end with the blue wrap. (this is a protective cover that hides the brushes)

The motor mount on this version is connected to the chassis with two bolts. I would have preferred something a little more robust here....but so good.

The shaft must be drilled and tapped to support the retainer washer and bolt that is on the OEM motor. My lathe was disassembled so I did this the old fashion way. I marked the punched it, and then drilled it by hand....with a little trick.....I ran the motor in the opposite direction while drilling. This gave me a really good feel of how centered the operations was.....worked pretty good.

If you measure this motor....base to shaft it's only about 5/16" taller than the original. The mount could be replaced with your own design or bend this mount to make up the difference. (but......I simply mounted the motor using two of the original 4 tapped holes on the base of the lathe, drilled and tapped two more {because this base is more narrow} and mounted the motor a little higher than the original. This allowed the v-belt to fit...and the timing belt can simply be tightened up with the normal mechanism) Even the shaft protrusion and motor face was in the right place or dang close enough to allow the pulleys and belts to line up.

You'll want to keep the C-ring that came with the motor on the shaft to keep the timing gear inside guide from pushing up against the motor face. The OEM motor has a slight lip that keeps this from happening. If I was going to do it right. I would have grooved the shaft to insure this ring doesn't creep.


Modifications to the Controller

First thing I had to do to the controller was add a toggle switch to reverse the polarity of the armature. This was done by adding a dual pole dual throw (DPDT) On-Off-On switch to the controller. Other models come with this switch installed. It's a simple thing to add and I can provide you with details if needed. Notice the picture at the top of this page shows two switches installed. The center one is the FWD-REV switch. There is a knock-out all ready for your use on the face of the controller.





Modifications continued

After wiring in the switch and putting the original speed potentiometer and run switch back in I ran the AC input wiring and DC output wires....along with a safety ground. There are two available 1" knockouts on the base. One at the top of the unit and one at the bottom.

My plans are to relocate all these controls to the front of the lathe by replacing the OEM front panel with one of my own design. That project is underway and you'll be able to read about it further down on this page.





Completed Controller

I choose to run both the AC and DC wires out the top as my original, less ambitious intent was just to mount this controller somewhere accessible and be done with it.

I quickly decided that just wasn't going to started the front panel replacement and motor control relocation project. Dang...If I ever get done modifying this lathe....I might actually make something useful.

If you choose to use this controller for your sure to check the jumper settings as it comes strapped for 220. If you're planning to use 220....good for you. I just didn't have an easy way of getting 220 over to my bench.....and as you read's just going to buy you allot of speed....and you'll have to limit your output of the controller as so you do not exceed the armature voltage of you motor. At 220 are going to make 180 out and the motor is only rated at 130 max.


Moving the Controls


Started work on removing the old controls and getting ready for the new faceplate and variable speed controls. Since the G0516 manual doesn't have any electrical schematics...I took time to document where all the little wires go just in case I ever want to return this thing to OEM. (don't know why I would ever do that). The cool thing about this is that there are three entrances into this space.

One is a plastic tube that comes from the rear of the lathe. (perfect for routing the control wires.

One from the spindle cover. This will allow me to hook up the spindle safety switch and the leads from the Tachulator sending unit.

And one from the lower cover that houses the AC line fuse and the Lathe/Mill selector switch.



Moving the controls continued...

Here's a shot of all the switches removed. The remaining black wires are the original AC line and the spindle safety switch. (plastic cover interlock)

The colored wires to the left are the signal wires from my Tachulator sensor.












Blank panel installed

Here's a shot of the blank panel installed. There are more shots of the milled plate later in this segment.







Installing the Tachulator

I'll skip the details on how I laid out the design. There is a pdf of the concept on the links to the left. You may be asking why I used such a thick plate and then had to mill out segments to place the components.

WELL....I didn't have any 3/16" aluminum plate and I like making aluminum chips...;-)

Anyway...It's going to be nice and stout.




more on test mounting the Tachulator

This is just a test of how the components fit before I move onto the mounting of the Run and Speed controls.

Fit like a dream.

Note to self. Get a 20 TPI leadscrew for the mill.






View from the front

This is going to be pretty dang slick when I get it finished. The Tachulator mount looks great and I can't wait to get the run switches and speed pot installed.

So what do you think....should I prime it and paint it Grizzly green?

Does anyone know how to make the polished aluminum swirl patterns? Do you think that would look better?

Done for tonight.....more later.






Panel 95% complete and installed


Well here it is. The new controls for my G0516. I decided against painting or buffing the panel.

The electronics store was out of boots for the bat switches but I'll get them soon.

I'll make my own knurled knob for the speed control in the next few days but first I have to get all the wiring completed and test the controls. After that I'll be working on some labels for the switches. Anybody have a CNC and want to make me some nice ones? ;-)


You've got to admit......this is going to be pretty dang nice!!! not to mention functional.


Drop me a line and give me your thoughts. Shawn





2/11/2006...all the wiring is complete and everything works as planned. This is so nice to have everything attached directly to the lathe. I don't think I'm going to paint the panel yet. I have added the boots and put a different knob on the speed control. I'll post a picture in the next day or so.


Last really important thing to take care of is to build a chip shield for the motor. Don't want any of that stuff getting inside and shorting things out.



All completed and working well