So, My workbee has more chatter than it should. I have removed the top brace and lowered the bed. I'm assuming this is the problem so I put the brace back in and built up the bed again. This is better but I've lost 60mm of travel in the z axis. I would like that back without pushing the problem elsewhere in the chain. Simple is better. I have some 1/2" (12.7mm) aluminum plate laying around. I was thinking of making new x axis plates. Just 2x as thick and with 100mm added between the wheels and the x axis extrusion. Is there any reason this would be a horrid idea?
You would still have the problem of deflection of the X C-beam which is probably a major cause of the chatter. Doing that and stiffening the X C-beam would be the way to go. Other mods extend the Y gantry plates, and I did a mod involving longer Y end plates (Rotary axis for Workbee). Basically though, the chatter is caused by the extension of the Z axis (increased leverage) and the C-beam deflection on the X axis. Alex
Also checkout High Z Mod for Lead CNC > post about repurposing it for Workbee use That second rail does a lot to increase rigidity
Hmmm..... I have most of the pieces for this already. I'd have all of the pieces if I didn't make a ridiculously overbuilt 3d printer with the rest of them.
Here's a question. I could back the X axis span with a piece of 8020 and got to linear rails on X and Z. That would stiffen things a bit and remove any flex in the 9,000 or so wheels in the gantry. I'd have to machine a couple of mounts and the two taller end plates but I think they would be straight forward to do.
So you went with taller Y end plates to reduce the leverage of stuff above the y axis? And this is, more or less, what the high z thing is trying to do. Well, we're heading into the time of ice and no sunlight so I'll have plenty of time to design whatever I want.
Actually I wasn't after more Z travel - I just wanted to make room to mount a rotary axis. I have taller (50 mm extra) Y gantry plates as part of an upgrade to linear rails (they increase the rigidity considerably) and I now have 140 mm of Z travel. I left the 20/80 bed supports (modified the layout a bit to accommodate the rotary axis) and they do help with the overall rigidity of the machine. Machined some aluminium recently - 3 mm single flute spiral upcut, 0.5m doc/woc, 13 K rpm, increased feedrate as I was running the job until I got to 2000 mm/min. I would in future increase the doc, but was my first job in aluminium since fitting the linear rails, so I started with the settings that worked with the V-wheels. Alex.
Stiffer z axis without wheels. That plate is too thick. I think 6mm would work and that is 12mm. The HGR20 could become HGR15 or MGN15. Not entirely certain how one would tram such a thing. I was trying to figure out how to jam a ball screw in there but that would be something of a monster and would make more sense if I was building an entirely new machine. I just want a bit more Z and the chatter gone.
Linear rails on the Z will help a bit, but flex in the X axis is a big cause of chatter. Swapping the V-wheels there for linear rails and adding some bracing to the X C-beam will help. Did you look at @Peter Van Der Walt 's suggestion of the high Z mod for the Lead? I've seen at least one post I think where someone fitted it to a workbee with a 1000 mm X axis. It will be interesting to see what you come up with and the results - more Z travel and less chatter is the challenge of course. Alex.
