Clough42 (On YouTube) recently uploaded a new video of his recently acquired PM-940M. He indicated he is installing a DROPro DRO. To provide a few ideas, I am attaching two screen shots of the mount and DRO on a model of the PM-940V I've created in SolidWorks. There are about 10 individual parts needed as well as fastening hardware. All of the parts are simple parts that can be made on a mill or lathe. I am in the process of making the parts and will attach the DRO when the parts are finished. When I am satisfied the design works, I will provide .pdf's of the part drawings and drawing showing the tapped holes in the mill castings as well as some annotated photos showing how I mounted the DRO.
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Adding a DROPro DRO to my new PM-940V
- Thread starter RodSME
- Start date
- Joined
- Jan 18, 2020
- Messages
- 3
I'm actually in the process of designing my own 4-axis DRO installation on the '940.
I'm looking at what you've posted here, and it looks like we're headed in the same direction for the X axis. I'm planning to build a bridge all the way across over the way cover, and you're supporting from one side. Either should work fine. For Z, I'm planning to mount the scale flat on the right side of the column and still debating whether to try to reach all the way around the shield, or just leave it off. For Y, I see that you opted to mount the scale flat against the casting and angle the read head. I was planning to mount the scale and read head vertical and take up the 20'ish degree angle in the mount. It's this angle mount that's giving me the most trouble. I can make pivoting brackets, but it's a lot of little parts. I was looking at a weldment, but that also gets complex.
How are you planning to deal with adjustability? I don't see anything in the images in your post. I was planning on using slotted holes and jacking set screws for alignment, but haven't started making any parts yet.
Two options for Z:
Bent sheet metal reach-around bracket
Machined from solid mount, no shield:
X Axis, shield removed for clarity:
Y Axis:
I haven't added all of the fasteners to the model because I'm lazy.
The thing I don't like about the Y axis is all of the little angle brackets. With two setups each, it'll just be a grind. It would be easy to do something with bent tabs, but the front bolt pocket is in an awkward place.
James
I'm looking at what you've posted here, and it looks like we're headed in the same direction for the X axis. I'm planning to build a bridge all the way across over the way cover, and you're supporting from one side. Either should work fine. For Z, I'm planning to mount the scale flat on the right side of the column and still debating whether to try to reach all the way around the shield, or just leave it off. For Y, I see that you opted to mount the scale flat against the casting and angle the read head. I was planning to mount the scale and read head vertical and take up the 20'ish degree angle in the mount. It's this angle mount that's giving me the most trouble. I can make pivoting brackets, but it's a lot of little parts. I was looking at a weldment, but that also gets complex.
How are you planning to deal with adjustability? I don't see anything in the images in your post. I was planning on using slotted holes and jacking set screws for alignment, but haven't started making any parts yet.
Two options for Z:
Bent sheet metal reach-around bracket
Machined from solid mount, no shield:
X Axis, shield removed for clarity:
Y Axis:
I haven't added all of the fasteners to the model because I'm lazy.
The thing I don't like about the Y axis is all of the little angle brackets. With two setups each, it'll just be a grind. It would be easy to do something with bent tabs, but the front bolt pocket is in an awkward place.
James
- Joined
- Jan 18, 2020
- Messages
- 3
I finally figured out something I like better for mounting the Y axis. I'll just weld a couple of tabs onto a piece of aluminum angle trimmed to the right angle.
I should be able to just clamp the angle down to the mill bed and slice it off with a slitting saw to the correct height to establish the angle. Jacking set screws can finish the job of truing it up.
I should be able to just clamp the angle down to the mill bed and slice it off with a slitting saw to the correct height to establish the angle. Jacking set screws can finish the job of truing it up.
Just a few observations. I see what you've done for the X axis reader. Should work, however mounting the reader near the center of the saddle may not be necessary. I think it will work with the reader on the left side of the saddle. That way, supporting the reader from the one side would be all that's needed. I've positioned the X axis scale near the left end of the table.
As for the Y and Z axes, be careful. I don't see the gib locks on your model. If they are in the same place as mine, I think you may have an interference. The Y and Z axis gib locks are on the right side of the saddle and the column of my 940V.
The side plate on the Z axis reader support is separated from the headstock support casting by two standoffs. These standoffs are long enough to clear the Z axis drive limit switches.
I carefully measured the angle between the side and top of the base. The model has that angle incorporated in it. There are slots in the brackets where adjustments are needed. The grub screws in the end caps of the scales will allow for some adjustment of the scale position. In ...pic01, I show the washers under the screws transparent so the slots are visible. The size of the slots for the Y axis reader mount plate allow for minor angle adjustment of the reader. The slots also allow the reader to move up and down for position adjustments. The horizontal bar the X axis reader is is mounted to has slots that allow the reader to move toward and away from the X axis scale. There are standoffs to support the reader bracket on the left side of the saddle as well as standoffs under the X axis reader.
The grub screws in the scale end caps separate the scale from the rear of the table .125" so as to clear the oiler on the back surface.
As for the Y and Z axes, be careful. I don't see the gib locks on your model. If they are in the same place as mine, I think you may have an interference. The Y and Z axis gib locks are on the right side of the saddle and the column of my 940V.
The side plate on the Z axis reader support is separated from the headstock support casting by two standoffs. These standoffs are long enough to clear the Z axis drive limit switches.
I carefully measured the angle between the side and top of the base. The model has that angle incorporated in it. There are slots in the brackets where adjustments are needed. The grub screws in the end caps of the scales will allow for some adjustment of the scale position. In ...pic01, I show the washers under the screws transparent so the slots are visible. The size of the slots for the Y axis reader mount plate allow for minor angle adjustment of the reader. The slots also allow the reader to move up and down for position adjustments. The horizontal bar the X axis reader is is mounted to has slots that allow the reader to move toward and away from the X axis scale. There are standoffs to support the reader bracket on the left side of the saddle as well as standoffs under the X axis reader.
The grub screws in the scale end caps separate the scale from the rear of the table .125" so as to clear the oiler on the back surface.
- Joined
- Jan 18, 2020
- Messages
- 3
Okay, that makes sense. I didn't realize you were bridging all the way over the limit switches. My mill has the control panel mount on that side as well, right where you show the Z slide mounted. Maybe yours is set up differently. The column casting looks a little different in your model.
What are the two button head screws in the middle of the Z read head mount plate?
The hole shown in my image of the Z axis is the location of the top gib screw. The plate fits under the lever and the scale is mounted back a couple of inches on the column to avoid interference with the locks.
For the X axis, I was originally hoping to mount the read head far enough to the operator's left that it wouldn't hit the column and I could pull the scale cover if I wanted to go back further in Y. It turns out there really isn't room to do that and keep the full X travel and keep the X scale on the back edge of the table, as I'm sure you discovered when you measured. Given that it had to interfere with the column, I just opted to bridge all the way across for rigidity. You're right; it's not necessary.
I see you're also using nuts on the head mount screws instead of tapping M4, so you have some adjustability there as well.
I like the use of round standoffs. That should help keep oil seeping out of the ways from migrating down the mounts. Not that it matters, but it'll avoid some of the mess.
What are the two button head screws in the middle of the Z read head mount plate?
The hole shown in my image of the Z axis is the location of the top gib screw. The plate fits under the lever and the scale is mounted back a couple of inches on the column to avoid interference with the locks.
For the X axis, I was originally hoping to mount the read head far enough to the operator's left that it wouldn't hit the column and I could pull the scale cover if I wanted to go back further in Y. It turns out there really isn't room to do that and keep the full X travel and keep the X scale on the back edge of the table, as I'm sure you discovered when you measured. Given that it had to interfere with the column, I just opted to bridge all the way across for rigidity. You're right; it's not necessary.
I see you're also using nuts on the head mount screws instead of tapping M4, so you have some adjustability there as well.
I like the use of round standoffs. That should help keep oil seeping out of the ways from migrating down the mounts. Not that it matters, but it'll avoid some of the mess.
The 940V doesn't have a Z axis drive standard. I decided to design a drive unit using a 24v DC motor from Amazon that is advertised as an electric bicycle addition. It sits on the top of the column. (I also designed an X axis drive similar to the drive I designed for my G0619.) The two screws on the Z read head mount plate are to attach a cam for actuating limit switches.