Hey Guys
My first post. I’m building a LR4, and today I bought my rail pipes and had them cut to size. They where sold to me as 32mm diameter, 3mm wall thickness (a little thick, but hopefully thats ok). When i got home and measured them, i found they are actually 32.5mm. Do you think that will still work, If i scale the core and bits up a little in the slicer? Or does anyone know of someone else in the community who’s built a machine with that size pipes?
Hey Leonard, 0.5mm is quite a lot. It might work like this, but scaling does not work since holes etc. would be in the wrong spots etc.
I’d return the rails, they sold you the wrong product. Arguments like “it’s already cut” or “it’s a custom order, no returns” etc. only count if the product isn’t wrong in the first place.
As for the thickness: mine were 3mm as well.
Agreed. Scaling is always the wrong answer, this is an engineered system and you can’t cheat it into compliance.
Your seller needs to supply the correct product or provide a refund.
You might take a look at their product spec sheets, and see what their advertised tolerances were. If it’s something like 32mm +/- .5mm, then they do have a reason to consider the sale final.
That would be shocking to me, tubing isn’t normally supplied with such lax tolerances.
Thanks for the advice. Perhaps I’ll print the core, and a X bracket as is, and see if it fits. If not, I’ll look for new pipes.
Ok, so the core fits on the rails, and has a little drag/friction, so that if I flick it accross the rails it will come to a stop after 20cmvof travel. It will slide accross the rails by itself when i tilt the rails to about 30-45 degrees. I havnt snugged any bolts down yet, but does that sound loose/free enough to continue, or should there be basically zero friction?
Welcome @Leonard_Long !
Ideally, Core should like a well lubed linear rail block with a balance of zero friction, and zero rocking/slop.
Hopefully some electrical engineer type will chime in to confirm/correct my understanding… Don’t slide the Core along the X axis too quickly/aggressively when steppers are wired up to the controller, since the motion will generate voltage back fed to the controller, and I’m personally not clear what protection the JackPot (or whatever controller you’re using) has for this scenario.
Personally like the tilt test idea… Just tried with my belted wired lubed 29.4mm EMT Core slides when the gantry is tilted ~15-20 degrees. But, I don’t know what good/normal/acceptable range is.
hope that helps!
Which has much more friction than if the belt wasn’t attached.
You’ve gone this far with rails that are oversize. You might (MIGHT) just get away with it. If it were me, I’d get the correct size rails.
It’s your build, and you’ve surprised at least me that it isn’t binding or breaking braces. At this point you might as well finish assembly.
The worst that can happen is you end up regularly breaking braces or you find that your X axis is hard to move when fully assembled and adjusted. At that point you’d be rebuilding the beam with new tube anyway. The good news is that you’ll be good at LowRider assembly after all that, so it won’t be the worst job ever.