I have a heavily modified Taz Workhorse that I purchased secondhand. It has a duet motherboard and BLTouch installed. I am using the BLTouch to create a mesh compensation grid, however I am seeing some strangeness in the bed when it is printed. The BLTouch has a quite sensitive trigger, yet I am seeing the bed assembly flex when it is probed by the BLTouch. Had anyone seen this before? Is there a way for me to shore up the bed assembly and make it more rigid? Thanks!
The BLTouch should not be touching the bed with any force beyond the minuscule weight of the sliding plastic probe assembly that is used for measurement. If you’re seeing bed deflection them something is way wrong. Are you sure your BLTouch is working correctly?
Aside from obvious mechanical issues knowable only by you, the one guess that comes to mind is maybe the modular build plate? On the WH, a PEI-coated glass plate sits on top of a stainless steel sheet adhered to a standard heating element below. This makes it easy to swap the glass/build surface, since it pops right out. The glass is held in place in each corner with a large steel washer and TPU corner feet. Stock lulzbots can’t level if all four corner washers aren’t screwed down tightly and making good electrical contact (and sometimes not even then 
). This corner assembly also keeps the glass plate tight against the bed surface. If your corner washers are even slightly loose, the glass build plate could have play that somehow allows it to tip or move in some fashion. I would make sure the four corner washers are screwed in, and that glass build plate has no play vertically or horizontally. Love to hear what you figure out.
So I’ve switched to an EZABL Pro from TH3D Studio, so I know it’s not the BLtouch poking the bed that is the problem. I’ve also tightened the leveling washers down. I am still seeing the same problem. I’m curious if it’s possible for the toolhead to somehow be mounted crooked? Or maybe the right z stepper is worn out and not working as well as the left? In running mesh compensation, it just seems that the printer should be accounting for this, but I for the life of me cannot figure this out. Any help would be appreciated. At this point I don’t even know where to look to identify the issue.
Maybe take a video? You say that the probe is not poking the bed, but you also say that the bed assembly flexes when it is probed. These seem mutually exclusive. so a video might be worth a thousand words in this case.
Closing the loop on this. Thank you for the guidance y’all. In the end, the final piece was finding that my right z axis belt was off center and grinding hard on the sides of the top bearing guides. I can see significant wear on the belt and will need to replace it soon, but after a morning of balancing the set screws, the printer is now operating the best I’ve ever seen it. Took y’alls confusion and reading the assembly manual for the workhorse to find the issue, so much appreciated.
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It’s always sweetest victory when you solve the riddle on your own.