Belt tension

[kissandra79 0]

I am a first time assembler of ultimaker. and i have thoroughly enjoyed the build process all the way till the part where i have to put in the X, Y axes rods and their associated belts. The problem is.. I am really not sure how freely or rigidly the extruder head must be able to move... right now.. i have assembled it in such a way that that the extruder head moves.. but the movement is a little tight for a typical human. Me in this case.

Can someone please give me some rule of thumb, as to how freely the extruder head must be able to move over the X and Y axis rods..when the machine is unpowered. The thing is.. I still haven't assembled my ultimaker entirely yet. I'm just waiting to get this part right before I proceed. .. just in case I make a mistake in this part..

Thank You.

PS: Thanks for the ultimaker : )

[IRobertI 520]

My head is quite stiff when moving it manually but it works great while printing. If you've made sure your rods are nice and square and you can move the head around without using excessive force you should just go ahead with the rest of the assembly (do make sure that the short belts are real tight though, push down hard on the motors and then tighten the screws). It is most likely fine.

You can tweak belt tension later when you start printing, it'll be obvious if it needs to be done or not.

[kissandra79 0]

Could you please tell me what you mean when you say "make sure your rods are nice and square". By "square" do you mean that the X and Y rods must be absolutely perpendicular to each other?

[IRobertI 520]

Exactly, everything should be as close to 90 degrees to each other as you can get it. Check the instructions here under point #10 and onwards. It shows how to use one of the wooden pieces as a crude measuring tool to help with alignment. Of course it doesn't have to be down to the micron but make it as close as you can, no reason to not do it when you've put so much effort into the rest of the machine

http://wiki.ultimaker.com/Ultimaker_rev ... e_XY-frame

Oh and there's a vid on that page about belt tension where you can see him moving the print head around very very easily by hand. My head is quite a bit stiffer than that video shows. IIRC the video shows an early machine where it was easier to move the head by hand, they stiffened it up for later versions.

[jcosmo 5]

My print head is stiff to move by hand but works well when printing.

It produces an interesting set of sounds whilst printing, almost tunelike when printing rapidly - esp on curves like those on some belt tensioners I've printed. I presume this is normal, but have not got round to recording it and asking someone to compare it to theirs.

[IRobertI 520]

That is very normal jcosmo, that's a sound pretty much all machines of this type makes. Some even use CNC-machines to play music.