Encoder Installation on PM-25MV Mill

[carbuthn]

Now that I have mostly finished my lathe conversion I am starting to work on a Precision Matthews PM-25MV mill.

I have the ClearPath servos installed and tested, working on the limit switches and spindle encoder, I am having some issues with the encoder.

Does anyone know of someone that is making encoder mounts for sale, drawing for making the mount or pictures of a mount that they have made?

I am planning on mounting a timing pulley on top of the spindle drive pulley, but have not been able to find a pulley with a large enough Id (45mm), I can make an adapter that will fit over the drawbar assembly if I have to (about 28mm) and screw it to the top of the drive pulley.

Any help or information / pictures would be appreciated, thanks,
Chuck

[carbuthn]

I didn't get much response or find someone that has added an encoder to a PM25MV so I have started to design a method myself and will document it here to try and give some ideas to others who may be converting a Precision Mathews PM25 mill.

I started by turning a jig to align and hold the drive pulley and timing pulley. The bottom diameter is just shy of 45mm, the upper portion is 20mm to fit a Aluminum XL 40 Teeth 20mm Bore Timing Idler Pulley.

I centered the jig in the bridgeport mill and set the DRO, with the set screws aligned to 45°. Moved off center with the X axis 26.25mm, Y Axis at 0.00mm. Spot drilled for 8-32 screw. Repeated for other 3 spots on the opposite side, front and back.

Then I drilled down to the base of the jig with #29 drill.

Drilled to bottom of the timing pulley / top of the drive pulley with a #18 clearance drill.

Removed the timing pulley and tapped the four holes for 8-32.

I will post additional pictures when I finish the encoder mount.
Chuck

[martyscncgarage]

Chuck, your method looks good. Sorry, I missed your first post, but I would have suggested exactly what you did. Just be sure to use the same tooth count on the encoder pulley and use a quality encoder and you should be good. Keep us posted on your progress.
Marty

[carbuthn]

Thanks Marty, Amazon has 40 tooth pulleys with 6, 8 and 20mm holes(I have the 8mm and 20mm hubs).

I will use the pulley with an 8mm hub mounted on an 8mm shaft between two pillow blocks bearings, with a small 8mm to 6mm coupling to drive the encoder (2500 ppr Koyo).

Still need to modify the belt cover before I can get the size of the mounting bracket and determine the belt length that I need to buy.
Chuck

[martyscncgarage]

You only need a 1000cpr encoder for the spindle.

[carbuthn]

I purchased the encoder back in February of last year when I got the mill. I believe that I had read that 2000 ppr was recommended somewhere (not sure, old age maybe?). Got the 2500 ppr from Automation Direct.

[martyscncgarage]

Should be fine....

[carbuthn]

Finally back working on the mill Again.

Made mounts for the X, Y, & Z limit switches.

Made mount for the encoder, but need to order timing belt to fit before installing the encoder. It will attach to a 3/8" bar the replaces the spacer to hold the original control box to the side of the mill, and allow for about a 1/2" of adjustment to tension the belt.

Still waiting on CNC4PC to send a replacement board to upgrade to the current version, Arturo said he would send the new one about a month ago. He mailed a package and sent me the tracking number, after about 10 days I got a delivery notice, it went to Porter, Co. (I live in Crystal River, Fl. about 3 hours drive from Port St. Lucie, Fl.). I sent him an email, and got a new tracking number 5/28/20, as of today it is showing that a label has been created, but not shipped (6/9/20). I have called three times since Monday, left messages, no response.

Guess I will scrap the Clearpath to Acorn born and use a PLC instead (already have an extra one).

Making the control cabinet from a sheet of PVC, thanks for the idea Franco.
Chuck

[martyscncgarage]

Very nice work!

[TCandee]

Just thought I would share my encoder install on a pm25 and pm833tv. I incorporated it into my power drawbar.

The pm833tv power drawbar didn’t have the air cylinder installed when I took the picture but you get the idea.