• Scam Alert. Members are reminded to NOT send money to buy anything. Don't buy things remote and have it shipped - go get it yourself, pay in person, and take your equipment with you. Scammers have burned people on this forum. Urgency, secrecy, excuses, selling for friend, newish members, FUD, are RED FLAGS. A video conference call is not adequate assurance. Face to face interactions are required. Please report suspicions to the forum admins. Stay Safe - anyone can get scammed.

Weiss VM32 CNC Conversion

gerritv said:
it's just a G20 or G21 away from being one or the other on the UI regardless of what your ball screws are. Those should always be part of your generated G code regardess.
Click to expand...
For those who aren't CNC savvy the G20 and G21 just mean that a move like
G1 X1.0 Y1.0 F20 moves
1mm at 20mm/min if a G21 is at the start of the G-Code file and
1" at 20in/min if G20 is in play.
 
After feeling good about the state of affairs on the conversion I ran into a snag today.
I’ve been having issues with the X axis binding at the ends of the travel. I thought it was because the gib was too tight. Slacked it off and it helped a bit. Removed it completely and presto, full travel with no binding. But I noticed that the table was not parallel to the edge of the Y carriage.

I believe the ball screw is not running parallel to the X axis ways because the slot where it mounts in the Y saddle is not perpendicular to the X axis ways so the whole ball screw is at a slight angle.
I ran the table to X+ to the point where the servo errors out and then undid the servo mount. It shifted over about a 1/16”
I’m going to try shimming where the ball screw mounts to the Y saddle and see if I can get it parallel.
Will only have to take the table off. Again. Sigh.
 
David said:
I’m going to try shimming where the ball screw mounts to the Y saddle and see if I can get it parallel.
Will only have to take the table off. Again. Sigh.
Click to expand...

Can't help with your CNC stuff, but I've seen this exact problem on manual mills before. The fix is to let the end caps float until you reach an extreme, then tighten down the end cap while the table is all the way at that end. Ie, let the end caps tell you where they want to be. Oddly, I just had this exact problem with my new Power X a few days ago. I fixed it the same way. Problem gone.
 
After morning chores were done I escaped to the shop.
Tore the table off and did a bunch of measuring. At first I thought the screw was not parallel so I put a 123 block in the slot and another up against the X axis dovetail. Using an engineers square I could not slide even a .001 feeler gauge in between the blocks.
I ran the table down to the full extent of the positive X axis and put the servo mounting bearing block on so I could spin the screw with a drill.
Ran the table to the full X negative and the put on the mounting block.
Ran it back and forth maybe 20 times and could detect no binding. The ball screw can easily be turned by hand at both ends of the travel.
The only thing I can think of is that the last time I reassembled it, the slots in the mount may have allowed too much droop in the ball screw which made it bind when the mount was near the ball nut and the was no flex possible.
So problem solved I hope.

X travel is 405 mm
Y travel is 180 mm
Z travel is 338 mm
 
Last edited:
David said:
After morning chores were done I escaped to the shop.
Tore the table off and did a bunch of measuring. At first I thought the screw was not parallel so I put a 123 block in the slot and another up against the X axis dovetail. Using an engineers square I could not slide even a .001 feeler gauge in between the blocks.
I ran the table down to the full extent of the positive X axis and put the servo mounting bearing block on so I could spin the screw with a drill.
Ran the table to the full X negative and the put on the mounting block.
Ran it back and forth maybe 20 times and could detect no binding. The ball screw can easily be turned by hand at both ends of the travel.
The only thing I can think of is that the last time I reassembled it, the slots in the mount may have allowed too much droop in the ball screw which made it bind when the mount was near the ball nut and the was no flex possible.
So problem solved I hope.

X travel is 405 mm
Y travel is 180 mm
Z travel is 338 mm
Click to expand...
Have you tried placing a bit of weight on the table and driving the X axis full travel from left to right? The weight will cause the ball screw to have more of a load on it. The same thing happens if the gibs are too tight. There might be some flex in the mount you made on the left side of the table. I would think it would only get stiff on the one end of the travel, not both.


Edit: read back to post #71
 
Perry said:
Have you tried placing a bit of weight on the table and driving the X axis full travel from left to right? The weight will cause the ball screw to have more of a load on it. The same thing happens if the gibs are too tight. There might be some flex in the mount you made on the left side of the table. I would think it would only get stiff on the one end of the travel, not both.


Edit: read back to post #71
Click to expand...
There definitely was flex in the mount I made when the gib was too tight. I just "plopped" my 8" rotary table on the table and everything still moves well to the full extent of the travel.
I am going to weld some braces to the mount though as it does flex a little bit.
 
That’s much stiffer now.
image.jpg
 
You must log in or register to reply here.
Back
Top