Pulleys and Belts
My previous printer didn’t have any way to tension the belts once they were installed. This was inconvenient and didn’t allow for easy maintenance. The new design includes screw tensioning on both the X and Y axes. The X axis includes a screw tensioner that pivots the motor to add tension to the GT2 belt. The Y axis relies on the idler pulley mounts to tension the belt. Before screwing the idler mount on fully the belt is tensioned as much as possible. The idler mount is then tightened down to tension the belt. Tight belts are critical for good print quality.
I decided to go with 10mm rails as they were a good quality/cost compromise. My previous printer used 12mm rails. 12mm rails are overkill, they don’t add any real print quality benefits to the printer. The increase in rail size and bearing size simply results in an unnecessarily expensive printer. 10mm rails don’t have any significant flex to them while still being affordable. If price is an issue, 8mm rails would suffice. The difference in quality would be minimal.
Initially I wanted to buy IGUS bearings. I had hoped that they would produce less noise than steel bearings. I ended up buying some cheap IGUS bearings from eBay. This was a mistake, the bearings I received produced far too much friction to be usable. I don’t know if this is a problem with all IGUS bearings or just my cheap Chinese ones. I ended up switching to some steel bearings. The sound produced by the steel bearings is noticeable but not unbearable. The cost of the genuine IGUS bushings, and the difficulty of buying them in Australia, made steel ball bearings the best option.
I would love to see some IGUS printers made. I would love even more to see some good IGUS, steel comparisons. That being said, do your own research, there are various advantages and disadvantages to both options.
Check out this video by Thomas Sanladerer: (https://www.youtube.com/watchv=ZGBipbgwgME&list=LLMFYmOZqnvSH77--DmoYhCQ&index=1112)
Couplers + Lead Screws
When building my previous printer, I learnt my lesson about buying cheap couplers and lead screws. When choosing lead screws and couplers don’t be tempted to go to cheap. You want straight lead screws or else you get Z-Banding. Cheap Chinese lead screws aren’t always straight. It’s a major headache and isn’t worth a few dollars savings.
Couplers can also cause problems. I found the “double locking” type to work well. These have a split in them which clamps to the shafts along with set screws. The “set screw only” types tend to be cheaper and nastier. I bought some that didn’t have centred holes. The locking type centre the shafts better and are generally made better.
I have had bad experiences with cheap screws and couplers, learn from my mistakes.