Printable x and y carriage replacements (Level 2 - Techie Consumer) (Page 10 of 11)

Haha don't just obey - it's a valid question, and deserves an answer I think.

It's about alignment - the tradeoff (in pretty much any motion system) for making something really rigid is it also has to be really accurate to not bind up (think CNC machines and ballscrews). By leaving a little room for the bearings to move (less, but still just a tiny bit flexible with a layer or two of tape), it will self-align by itself. Epoxy is pretty fixed and rigid, so if you get it even a smidge out of line initially it will run really rough...

The flexibility even with the tape will be very low compared to the bed and frame movement - this and the cost probably being the main reasons there aren't a whole bunch of "metal carriage" mods for the solidoodles.

If on an SD3 or 4 they are 334mm long and 8mm diameter.

50mm M3 is the only hard to find size you will need. Make sure they are threaded all the way through. Might as well pick up 16mm M3s if you don't have any, they're cheap and I feel like this one box i bought will never run out. 20mm M3s come in handy for certain parts like the extruder, which I think requires that 4 extra mm to reach the motor.

If you're cutting the belts yourself, some 30mm M3s are good to have around in case you cut too short.

Or do they not need to be socket head?

I have never found fully-threaded 50mm socket cap M3s, I'm not sure they are really a thing, I've searched pretty extensively. Get a pan head phillips, it will work just fine. I wouldn't use a button head, remember you have to turn a 50mm bolt all the way through. Not exactly fun with a tiny allen key, especially if you end up needing some torque. They also strip really easily in my experience. I had to take a drill to some button heads on an SD2 I just got--stripped the head trying to remove some bolts held in with red loctite. Probably wouldn't have stripped them if they were normal socket caps.

Not a chance. This is solidoodle. The bolt was just smothered in red loctite and thrown in place. Fire didn't work, but I did try that first! A combination of the tiny Allen key making it hard to get torque, and slipping easily, made that one pesky bolt.

Point being, I avoid button heads and get a socket cap or Phillips when possible The worst possible bolt choice though is the flat head, in my opinion. Not recommended if your bolt is even slightly difficult to reach or see.

It is an SD4

I should ask about Y then as well, as that is 14mm shorter than I had seen elsewhere. :-/

Is it worth converting to GT2 belts at the same time for the X axis?

What parts are different?

FYI both Amazon and McMaster Carr seem to have 50mm, full thread socket head. I ordered them. I may have a couple of extra sets of bolts to trade when things finally show up.

Just a word of caution about re-using the stock SD smooth rods... I re-used the Y rods initially and am now paying a price for it. They are NOT hardened and the bearings have worn some nasty little gouges in them causing issues with my prints.

We did replace the X rods right off the bat, not wanting to destroy the stock carriages to get those rods out. Purchased a nice 8mm case hardened, chrome plated rod  that was 30 in long & we cut to appropriate length ourselves.

the X rods show absolutely NO wear. The Y rods (original SD rods), however, are in bad shape.

Luckily, I had purchased another 30in length of the good rod for use on a 2nd SD4 - that one will have to wait until I can get more ordered as the current piece is being appropriated for the 1st printer to get it back up and running.

for anyone interested, this is the rod we ordered: http://www.amazon.com/Linear-Motion-Len … ds=8mm+rod

That design is pretty similar to what the Lawsy carriages actually do. If you upgrade to Lawsy's carriages you will have to cut your belts, punch holes in them and replace the front idlers. Those front idlers are a source of slop because as you speculate the design is terrible. The Lawsy design is very precise and you should be able to get both belts perfectly tensioned without worrying about the rod being dragged by an uneven pulley. I printed on belts for almost a year (at speeds >150mm/s) before I switched to fishing line and you have nothing to worry about, they won't break under Lawsy's design.

EDIT: I almost forgot, pirvan did a belt tensioner design for SD carriages:
http://www.soliforum.com/topic/8977/alt … ng-method/

Is this the correct bearings to get? Just want to make sure.http://www.amazon.com/Sprite-Science-Li … ords=LM8UU