Broke Beamer
I have just had a interesting development with the HB2 router. Most of my readers realize I push my inventions to the limit, actually breaking things from time to time. The Proxxon lathe is but one example. Not saying that I plan to break things but how else do I know where the break points are?
This one is a bit curious as what I broke this time was one, actually both of the helical beam clamp-on shaft couplings for the dual drive Y axis. One of the couplings totally failed (broke in two pieces) so that really caught my attention. The other had a clicking sound. Actually both had the clicking sound but I was not sure what the reason was. Now I know.
The dual drive was the hardest to get fine tuned (alignment and sticking spots) and suffered some abuse. No not the large mallet I joked about in another report. There were many times when I stalled the steppers trying to go too fast. It is pretty hard on the works when one motor stops and the other keeps going. I was also getting aggressive with short ramp times and was certainly slamming the couplings on several other occasions. Top speed at 4000 SPI on 5 TPI screws is 150 IPM. I’ll probably run my rapids at 100-125.
But Hey! That’s what it is all about when you make your own. No manufacturer to blame. I love it!
The HB2 is much larger and heavier than the Taig mill I have been playing with for years. There is more mass in motion. Therefore I have to pay more attention to Newton’s laws of physics. The hard Part is the MACH3 stepper tune up instructions say to set the motor speed and ramp times until they sound right. That’s a big help. They always sound right to me.
The X and Z couplings are still fine. Those axis run sweet as can be. I am the guilty party for the Y failure. I removed the preload on the Y shafts at one point and actually created some temporary end play. I bet it was at that point the couplers were streached and cracked. In fact I have replaced both the Y couplings with smaller diameter couplings. The clicking is now gone and the screws run very sweet in tandem under slight preload.
The Kerk screws are wonderfully smooth. Turning them by hand reveals a very low friction with the Teflon coating. I’ll bet the Z axis would turn by gravity if the stepper wasn’t connected. I found an interesting way to find the tight spots on the X and Y screws. I ran the axis back and forth then used the back of my hand to sense warm areas (radiation) from the screws. Yes it works. From the warm area I could check the track or screw for alignment problems. Now it runs like a dream. Only cost me one set of couplings… oops.