Hi guys (and gals), I have a Workbee 1510 and have managed to destroy a couple of really nice pieces I was working on due to one side of my gantry binding and pulling the machine out of square while cutting. It has seemed random at times, but it does tend to happen near the center of the y-axis travel, almost always when moving in the positive Y direction. I initially thought it might be a problem with the wheels, as they seemed very tight, so I loosened them and adjusted the eccentrics a little looser and tried again with the same results. I'm beginning to think now that the problem is more of a sagging issue in the y-axis c-beam causing the carriage to bind. As for potential fixes, I'm wondering if anyone has done the "quenbe" upgrade on a 1500mm axis and how viable a solution that is. I've also considered cutting the c-beams from 1500 to 1000mm to alleviate issues with sag/flex. If anyone can speak to either of these, or something else, please do! I've reworked my x and z axes already, and don't really have any perceivable issues there. Any help would be greatly appreciated. Thanks in advance.
Is it binding or is it the stepper is loosing steps? If you slow down your feeds, does it not bind? I’d run a job with the system in open air and see if it still happens. Slow down your feed a bit and allow for more torque from the steppers. as for the quenbe upgrade. It uses linear rails which helps a lot with the rigidity of the system. Always a good thing. But there are a lot of people using the wheels with out issue. Same with shortening the axis. There are many with the longer axis, so could help but probably not needed. what steppers are you using now?
Thanks for replying. I'm running high-torque nema 23 motors (2.45nM). I ran this particular job in a piece of foam prior to running it on wood, but also ran it to completion without any issues on a test piece of wood with no problems. I slowed down the feed after the first incident. It was still recoverable at that point, but happened again and that was the end of it. I don't know if the motor is losing steps or not. I replaced the stepper drivers that came with the kit, as I thought I was losing steps a while back, but haven't had those type issues since upgrading them. What's the easiest way to determine if that's the issue? Edit: I don't think it's just missing steps. The motor goes "brrrrtt" when it binds up. Like it's turning but clicking over because it doesn't have the torque. Maybe the motor is bad? But if that were the case, would the problem manifest itself more consistently?
I've had this happen & I think it's mostly from vibration causing the nut blocks to bind on the lead screws. I dealt with it when I first built my machine, then got it working fairly well for a while but as things started to wear it eventually happened again. I had to lower my max feedrate permanently. & I think why it's not consistent has to do with the 'frequency' of the vibration, which depends on what the machine is doing.
Thanks for the replies. I'll take a look at the nut blocks and check the wiring connex also. I haven't used it that much, so it would be a little disappointing for the nut blocks to have worn enough to be a problem already.
A little follow-up. Disassembled the right side of the gantry and checked things out. Wheels seemed sluggish, so removed them and cleaned and lubed them with silicone. Removing the gantry plates, they seemed a little bit tight as well, as if the spacers didn't have quite enough of a span to begin with. I didn't remember noticing this when putting the machine together. Putting it back together, I was conscious of this and made sure not to overtighten anything. The nylock nuts seem to do a good job, so I'm not too worried about it. Also, the nut blocks seemed to have some odd wear a little bit of plastic fuzz on the outside of the holes that I was able to just brush away. I loosened the screws that held the nut blocks to the plates and didn't tighten them until I got the cart back in place with the lead screw threaded, again making sure not to overtighten. Then I ran across this on RE: the quenbe upgrade: "The original design spaced the nut blocks using the bolt and standard metric spacers. While this worked, the nut blocks were very easy to misalign and adverse movement of the nut blocks resulted in the feed rate being limited. The quenbe PRO overcomes this issue by securing the nut blocks in place using a specialised spacer block. With our new specialised secure spacer block there is no unwanted movement in the nut blocks due to the extended standoff." So brrian, looks like you were correct about the nut blocks. Things seem to be moving better when jogging, so I'm going to try running some stuff with reduced feedrates and see how it goes, but I think I am going to go the quenbe upgrade route. Thanks to those that responded. CTH
Did this fix your issue long-term? I'm having the same problem now, and I'm wondering if the change in temperature has had something to do with it.
I fixed my issue! I removed the leadscrew thinking it was an issue with the nut blocks. Nope! It was the thrust bearing by a y stepper motor. I think some debris got inside the brass bearing cage and started tearing the brass apart slowly. Totally makes sense with the leadscrew binding intermittently. Next step is to print some enclosures for the bearings to prevent this in the future.
