Simple adjustable slider clamp for He3D K200, K280 and similar kossel deltas by Nanocube

Last crawled date: 3 years, 1 month ago

Replaces the stock injection moulded slider clamps of my He3D K280 kossel delta; the stock item is actually fine, but this version has a simple adjuster mechanism, and is sized for a 9mm belt upgrade I made.
Updated with 4 new Models (March 2020) - This is a updated design with thicker pin supports and 4mm more adjustment travel.
Models are provided for 40 and 42mm pins, plus 6 and 9mm belts: A stock K280 has 6mm belts and 40mm pins.
The stock He3D 4 roller carriage backplate design is actually quite good, and I think the 20x20mm spacing for the mount bolts is common to a whole bunch of Kossel designs.
Printing:
Use support for the pin arms and slider bracket. I originally printed these in PLA and they worked fine for a year, But I re-made them in PC-ABS (horrible material to print with, but very strong and stable) when I updated the design.
Fitting;
fit both pieces but only fully tighten the upper bolts, leave the lower loose enough so the slider can slide. Then fit the belt, making it tight'ish on the clamp. Finally tension the two pieces with a thumb and finger on the ends to a firm tension on the belt, don't go mad.. but it's OK to squeeze reasonably hard, the belt should thrumm like a double base when plucked.. Finally tighten the lower bolts while maintaining the tension; and after a few hours of printing and settling in it's a good idea to re-tighten and check everything.
Good:
8mm of tensioning adjustment possible via slider, allowing final tension to be set after the belt is fitted.
Standard 4 mounting holes on 20x20 grid, uses original bolts
Arm pin width is 40mm; matching the stock k280 part, this is parameterized in the scadfile and I have also uploaded 42mm wide versions.
Up to 9mm belt, also parameterized, I have uploaded 6mm versions of the model, these are probably lighter; but not printed or tested
Extends to the top of the carriage plate to hit the standard K280 endstop
(is is important that you check this before the first homing move!)
IR blade cutout at the top, I, however, use it to mount a magnet and have magnetic reedswitch endstops.
Simple and strong shell, none of the detail is random; there are elements of the wall layout etc designed to help the resultant print be strong where needed.
I tap the hols for the arm bolts, there is no nut recess, the hex-shaped hole will grip the original bolt very firmly and my experience of using an identical fitting on the effector end of the arms for the last few months has been good.
Arm clearance appears to be as good as, if not better than, the original
Ungood
The lower mount bolts really need a washer to allow you to tighten them enough, make sure it is 1mm or less in thickness or you may foul the belts.
Approx 5g heavier than the original, I think this isn't tooo bad considering this also has adjustment. ymmv.
The slider part will need support to print.I played with a supportless design but it was heavier and fouled the rods more easily.
Finally; The scad file is also there if you want to remix, laugh at my mistakes, etc. OpenScad 2016.11 or later is needed for the clamp to render properly.