I am working on designing a new larger print bed holder for a larger printer that I'm working on from scratch. Dimensions should come out to be about 18"x18"x18"/20".

Currently printing out pieces for the gantry controls on it. Have to finish up the bed holder itself and reprint it, seen a few things I did not like in the print.

If you look on McMaster you can see the tolerance of an 8mm drill rod is +/- 0.013 or +/- 0.025mm depending on type while the tolerance of a hardened steel shaft is -0.009 to +0.000mm.

Thank you, I did not notice that. I wasn't looking at tolerances, just thinking of other stuff around the shop that comes in 8mm and is pretty hard and straight. Stupid me!

If you're having trouble getting 8mm rod, try searching for "drill rods". They're the hardened steel rods that people make custom drill bits with so the tolerances are pretty tight. a 36" rod should be in the $10-12 range.

This is not good advice.  A "drill rod" is typically of a looser tolerance than a "hardened steel shaft".  There is a reason drill rods are a lot cheaper.  If you look on McMaster you can see the tolerance of an 8mm drill rod is +/- 0.013 or +/- 0.025mm depending on type while the tolerance of a hardened steel shaft is -0.009 to +0.000mm.  Any + deviation is going to cause grinding, hard motion or binding on your bearings and therefore print errors.

I do not recommend ordering drill rod instead of hardened steel shaft just because it is cheaper.  I have bought hardened steel shafts from McMaster and Folger tech with good results.

It's a work in progress but trying to think of a way to add the slop nut to it. It's a 15:35hr print so it's a pain....Also it will have to be printed in pieces since it's going to be so large, even if it's a print for an sd3.

I'm looking to do this upgrade very soon as soon as I get my e3d sorted out. I live in Australia and I'm fairly sure that mcmaster don't deliver here. I've already got my LM8UU's and some spare m3 screws.

I've replaced one of my rods in the past after I realised that my glass bed wasn't warped but the stock shaft was severely bent. I went to a local stainless steel shop and got them to cut me a rod there. Probably not the most reliable place for a precision shaft haha.

Anyway I'm wondering if anyone knows any other place that I could get some high quality shafts like the ones that mcmaster sells. Any help would be great.

Thanks,  Matt

I'm in the same situation, in that mcmaster is not an option. In ebay there's some 8mm shafts available, and these are for RepRap Prusa. Can't link directly for some reason, but you'll find them on ebay with a search like "Prusa i3 Rework Single Sheet Frame T8 Rod 8mm Smooth Rods Rail Bar Linear Shaft".

There's 6 usable shafts (i.e. long enough, need to be cut in length) for around $35,- Seems reasonable, wonder if anybody has any experiences?

veehoo

I've replaced one of my rods in the past after I realised that my glass bed wasn't warped but the stock shaft was severely bent. I went to a local stainless steel shop and got them to cut me a rod there. Probably not the most reliable place for a precision shaft haha.

Anyway I'm wondering if anyone knows any other place that I could get some high quality shafts like the ones that mcmaster sells. Any help would be great.

Thanks,  Matt

280mm but tbey don't have to be precise. That measurement comes from Lawsy's instructions so I take no responsibility if it's wrong.

That sounds right but they are the same length as the stock rods so just measure those.

I thought old rods/shafts could be re-used if you can cut old carriages loose from them clean?

sure, but the ones on the printer are junk compared to what you can buy 3rd party. right now im using my bent-as-hell stock x rods on my x axis. I broke away the old carriages pretty easily with just one whack of a hammer. They're printed at like... 30% infill, so obviously the carriages didn't survive.

If you're referring to length, get something longer than you need and cut it.