if it's not one thing it's another.
I got my replacement parts for my Huxley from RepRapPro a couple weeks back, and while I was on vacation last week set out to do a marathon build session....
The new printed parts are consistently printed 1-2mm thicker than they're supposed to be in certain dimensions. I checked using calipers. It was bad enough that some parts were utterly unusable, in that the holes for certain screws were deeper than the screw was long.
Of course, this didn't become apparent until I hit the Z-axis assembly stage, b/c the over-thickness was taken up in the rest of the assembly by using up every bit of spare thread on the threaded rods. Being too pissed off to bother going round the rosebush again with RepRapPro on this, I resorted to some creative milling and some use of the old poor-quality PLA parts (although if they ever get around to asking for the original parts in exchange, I'm giving them a big ol' raspberry. Spare parts in exchange for my frustration seems fair).
I actually think it was going okay, until I tried putting the X-axis parts onto the Z-axis rods. Now I've got a serious snag. You see, these printed parts accept some clip-in Igus bushings like this. The instructions say to ream out the holes that hold the bushings using a 7mm drill bit, which I've done. But even after removing enough material that I'm nervous, the bushings still grip the Z-axis smooth rods so tightly that gravity can't pull down X-axis assembly down (I'm confident it's not an alignment issue -- I feel the similar resistance with only one rod attached). Which means that when I try to drive the print head down, these "anti-backlash springs" aren't going to be able to do their jobs.
So, Googling about comes up with nothing. And pinging some of the RepRap discussion fora have generated silence. So I'm stuck trying to figure out, just how much stiction is enough/too much on these rails? And why reaming out the holes to the design diameter hasn't worked? And just how much more material can I ream out freehand before I compromise the stability of the axis?
I got my replacement parts for my Huxley from RepRapPro a couple weeks back, and while I was on vacation last week set out to do a marathon build session....
The new printed parts are consistently printed 1-2mm thicker than they're supposed to be in certain dimensions. I checked using calipers. It was bad enough that some parts were utterly unusable, in that the holes for certain screws were deeper than the screw was long.
Of course, this didn't become apparent until I hit the Z-axis assembly stage, b/c the over-thickness was taken up in the rest of the assembly by using up every bit of spare thread on the threaded rods. Being too pissed off to bother going round the rosebush again with RepRapPro on this, I resorted to some creative milling and some use of the old poor-quality PLA parts (although if they ever get around to asking for the original parts in exchange, I'm giving them a big ol' raspberry. Spare parts in exchange for my frustration seems fair).
I actually think it was going okay, until I tried putting the X-axis parts onto the Z-axis rods. Now I've got a serious snag. You see, these printed parts accept some clip-in Igus bushings like this. The instructions say to ream out the holes that hold the bushings using a 7mm drill bit, which I've done. But even after removing enough material that I'm nervous, the bushings still grip the Z-axis smooth rods so tightly that gravity can't pull down X-axis assembly down (I'm confident it's not an alignment issue -- I feel the similar resistance with only one rod attached). Which means that when I try to drive the print head down, these "anti-backlash springs" aren't going to be able to do their jobs.
So, Googling about comes up with nothing. And pinging some of the RepRap discussion fora have generated silence. So I'm stuck trying to figure out, just how much stiction is enough/too much on these rails? And why reaming out the holes to the design diameter hasn't worked? And just how much more material can I ream out freehand before I compromise the stability of the axis?