Pm932 Removing Worktable

[65Cobra427SC]

Before I move my PM932 from the garage I want to remove the worktable to reduce the weight and give me more clearance while it's being moved down the hall and into the workshop. It's still sitting on the pallet although the sides and top of the crate have been removed. It has both a DRO and Power Down Feed. Since this is my first mill, I only know the basics... so if any pictures are available they would certainly help... and be gentile

Some thoughts after taking a look...

Not sure how to disconnect the worktable from the DRO... I noticed the sensor attached to the back of the table but don't want to screw things up.

Not sure how the worktable is actually removed. Do I end up cranking it completely forward and pulling it out at the front? Or is it lifted off after certain bolts underneath are removed?

 

[RJSakowski]

I have not dealt with a PM 932 but it looks similar to the Grizzly G0755 we boought at work. Most DRO scales are connected with a cable with a DB9 connector at the readout. Disconnecting the DB9 connector and any retaining clips is probably the easiest way to separate.

If you are referring the the bed, it is held in place by the dovetail and lead screw nut. You would have to remove the dovetail adjustment gib and disconnect the leadscrew nut or unthread the leadscrew to separate. Also the power feed assembly and thrust bearing from one or both sides. The table should then slide out. It is a fairly complicated job for a novice as you will have to readjust your ways on reassembly but not impossible.

If moving the mill intact, the table can be moved around to get through doorways and around corners. At 1100 lbs. that is a formidable beast to move. It is also somewhat top heavy. We purchased a dolly to move the Grizzly and had one of the wheels collapse. The next two times it was moved, we had professionals do it.

 

[toddimus]

One possible word of caution on the DROs... I don't have DROs yet, but I'm almost positive this is how they work...

If they are glass DRO scales, the read head must stay connected to the scale. That means you can't just undo the DB9 connector at the display. You will have to unbolt either the read head or the whole DRO scale assembly from the machine's base. If you are removing the whole saddle (X and Y axis) together, then you presumably could remove the DB9 connector for the X axis but you would still need to deal with the Y axis DRO scale needing to stay connected to its read head.

I hope that makes sense. I don't want you to break your new scales before you get a chance to use them!

http://dropros.com/Digital_Readout_DRO_Installation.htm

Here's an install and cautions article from DROPROS.com. Scroll about 2/3 of the way down the page until you get to "DRO KIT INSTALLATION", after all of the customer install photos. They have laid out a seemingly good installation procedure. I plan to refer to this document heavily once I get my DRO components.

 

[RJSakowski]

One possible word of caution on the DROs... I don't have DROs yet, but I'm almost positive this is how they work...

If they are glass DRO scales, the read head must stay connected to the scale. That means you can't just undo the DB9 connector at the display. You will have to unbolt either the read head or the whole DRO scale assembly from the machine's base. If you are removing the whole saddle (X and Y axis) together, then you presumably could remove the DB9 connector for the X axis but you would still need to deal with the Y axis DRO scale needing to stay connected to its read head.

I hope that makes sense. I don't want you to break your new scales before you get a chance to use them!

http://dropros.com/Digital_Readout_DRO_Installation.htm

Here's an install and cautions article from DROPROS.com. Scroll about 2/3 of the way down the page until you get to "DRO KIT INSTALLATION", after all of the customer install photos. They have laid out a seemingly good installation procedure. I plan to refer to this document heavily once I get my DRO components.

My bad! Thanks, toddimus, for the catch.

Yes you do have to remove one or the other. Usually, it is easier to remove the pickup head as the mount has two or three fasteners. If you remover the scale, the realignment is more complicated and the is a greater danger of damaging the assembly.

On the scales that I installed, there was a blue plastic shim with a fork that slid between the scale and the pickup to set the proper alignment when installing. The shim also had four mounting holes to fix the pickup to the scale for shipping. The shim thickness is .050" but from what I have read, the clearance isn't all that critical. If the OP chooses to go that way, I would recommend making a shim and inserting it and then taping the pickup to the scale with the blue masking tape.

Cobra, I have three of the shims. I don't know if mine would fit your scale , but if it will, I would be happy to drop one in the mail for you.

Bob

 

[65Cobra427SC]

Thank you both for the info and for keeping it simple enough for me to follow... and it all made sense, which is an accomplishment for me.

Not sure about the glass part but the read head is connected to the scale. Since I wanted to remove the display as well, I disconnected all the DB9 connectors and put it in a safe place. For the X-axis, I zip tied the wire coil to the table which should work fine since I plan to remove the entire saddle. The Y-axis made me nervous for a couple reasons... the brackets used to position the read head look like they could withstand a nuclear attack, and access to the 2 small Allen head bolts holding the read head is very limited, so I haven't done anything with it yet. I plan to take another look at it this weekend but I may need to sacrifice an Allen wrench on the grinder to gain access.

Thanks for the link toddimus. I haven't read it verbatim yet but did take some time to look it over and it looks to be exactly what I need. I was slightly disappointed that the pictures in that section you referred to, showing the read head and scale, couldn't be enlarged but that's a minor complaint. Otherwise I will read it carefully this weekend.

Thanks for the offer RJS. I did notice the blue shim in the link toddimus posted but checked the boxes and none came with my mill, so it looks like I could use one. I'm going to get a hold of Matt first because if he has any, I can pick up one from him (I only live 30 minutes from his business... one of the reasons I purchased from him). Otherwise, I'll PM you with my info so you can mail one to me.

Hopefully everything will go smoothly with removing the saddle, but either way I'll be posting in this thread. If you see anything like HELP!!! then you'll know I'm in trouble.

Thanks again.

 

[RJSakowski]

Thanks for the offer RJS. I did notice the blue shim in the link toddimus posted but checked the boxes and none came with my mill, so it looks like I could use one. I'm going to get a hold of Matt first because if he has any, I can pick up one from him (I only live 30 minutes from his business... one of the reasons I purchased from him). Otherwise, I'll PM you with my info so you can mail one to me.

Thanks again.

If you can get them locally, great. Try to get one for each axis and store them for future use. There should also be four small metric screws for each, maybe M3 x 6mm? They would normally be thrown out or into a possible bin once the DRO is installed. Your vendor should have them from your install.

Otherwise, the offer still stands.

Bob

 

[toddimus]

...
Not sure about the glass part but the read head is connected to the scale.
...

The glass is a thin strip mounted (probably laminated somehow) to the inside surface of the long scale part. That's why it's so fragile and they make me nervous.

There are little lines marked at even intervals on the surface of the glass that the read head picks up to measure the travel.

As a geeky aside, you might wonder how they can register 0.0002" resolution with lines marked on the surface of the glass. That's really, really small!! The lines are not spaced at 0.0002" on center, but rather 0.0008" on center (I think). Still, that's a lot of little lines marked on the glass and there's a good reason those scales are so expensive. Google "quadrature encoder" for an explanation on how they not only increase the resolution of the lines by four times, but also get direction information. It's pretty clever.
/geeky aside

I bet Matt has a pile of those shims at the shop and would be happy to hand a few of them over to you.

Good luck!

 

[coolidge]

We purchased a dolly to move the Grizzly and had one of the wheels collapse. The next two times it was moved, we had professionals do it.

 

[65Cobra427SC]

Matt responded to my email and preferred I remove both DRO scales completely. He said they are sturdy enough to remove and replace if I'm careful, but if I leave either of them on and accidently hit one while I'm removing the table, it's a goner. Since he feels removing them is a lot safer I'll carefully remove them both. Apparently if you take one of the end caps off the scale you can take the reader head out but don't get this wrong, he was NOT telling me to do this... and I have no intention on trying it either. And they are glass scales... said the reader rides on little ball bearings along the glass. He was okay with everything else I did so I'll remove both scales next.

 

[65Cobra427SC]

I ended up removing all three scales and brackets... removed the X and Y scales so I could remove the table... removed the Z scale so it won't get damaged while lifting the mill with a strap. Now that they're off, it's not that bad. In fact once the mill is in place it will make it easier to clean and I'll be able to do a more thorough job so that's a plus.

Going to take a look at the table now, along with the dovetail, lead screw and anything else that might get in the way to make sure I know how to get it out. When it comes time to lift it, I can always get the guy next door to give me a hand.