We're stuck on calibration and pulleys

[LePaul 312]

We made really good progress tonight, my co-worker took over on the mounting of the print head to the XY axes We have them in but we watched the video over and over again on the wiki and not sure what's "tight" or not

We also haven't tightened the pulleys into place yet (set screws) as we aren't entirely sure how far they should be from the caps

So, we are at this point (step 9 ) http://wiki.ultimaker.com/Ultimaker_rev.4_assembly:_Extrusion_head

Any tips you can share?

Thank you!

 

[gr5 2,004]

You can just move on and it will work even if things are out of alignment or too loose or too tight.

Anyway, did you listen to the pitch in the video - you don't need the exact pitch on the long belt tightness - just it shouldn't flop like there's no tension and it shouldn't be so tight it has a mid range pitch. It should be a low pitch - they should seem on the loose side of things. If they are too loose you will have play and you will see a pattern like this when you print solid layers:

http://umforum.ultimaker.com/index.php?/topic/1872-some-calibration-photographs/?p=14474

 

So don't worry about it too much as you can adjust later.

The slider blocks should be clamping on the rods to the print head as tight as possible. You probably knew that.

The pulleys should line up with the belts. In other words, slide the print head into each corner and as you do the belt will either go straight into the pulley or crooked. If crooked slide it along the rod until things are straight. If it isn't perfect you will probably hear a clicking sound when you print - not a big deal. You can always adjust it later. The clicking sound is the belt riding up onto the pulley a little and then snapping back into place. It will print fine but make this noise to let you know that you should fix it eventually.

Just slide the head around and make sure things are all aligned nicely. Don't worry too much about it.

 

[gr5 2,004]

I mean when you get to the platform - that's where I had to do the most sanding and fudging to get it all to fit.

 

[LePaul 312]

You're 200 miles away...so don't be surprised if we get frustrated and offer to meet at Fenway LOL

Our belts sound fine...I guess we're being over cautious.

We are also finding that the comments at the bottom of the Wiki are very helpful too. Other builders have observed directions that were in reverse, etc. Hopefully the Ultimaker guys will review those spots for clarity

The platform went together pretty well for me..asides having oily hands from the bearing packaging...then trying to work those wood pieces around...but, it seems to be OK. We shall see

 

[gr5 2,004]

You're 200 miles away...so don't be surprised if we get frustrated and offer to meet at Fenway LOL

 

You are welcome to come visit!

I'm going to Maker Faire in NYC on September 21,22. Interested?

http://makerfaire.com/

Ultimaker will have a booth or something. If you break something maybe they'll give you a spare part, lol.

 

[LePaul 312]

Tonight we are reviewing the info here http://wiki.ultimaker.com/Calibrate

How "flush" should the pulleys be to the sides/caps? Or should they?

As we read through this, that's the one question we still have

 

[illuminarti 18]

The short belts need to not catch on the frame... so just inset them slightly, so they don't. Then the pulleys for the long belts need to be positioned as noted above, so that the upper and lower lengths of belt are directly in line with each other, and where the belt goes through the sliding block.

The short and long belt pulleys on the axes can touch one another if needed, as they will never rotate independently of one another.

 

[LePaul 312]

Thank you for your reply

So the short belts ,which would mean the shorter rods...the ones that are on the back and front (as viewed from the front of the machine)....should have some spacing away from the caps. So, about the same as what the coupler on the z-motor has?

 

[illuminarti 18]

I don't understand what you mean about shorter rods? The front and back rods form a drive pair, and the left and right rods form a pair. Each pair has one short belt attaching it to a motor, and two long belts attaching the rods to each other (and to one sliding block on each long belt).

The X axis (left-right) motor sits on the back wall, to the right of the printer, and is connected to the right hand axis rod.

The Y axis (front-back) motor sits on the left wall, towards the back of the printer, and connects to the back axis rod.

The belts need to pass over the pulleys without any twisting... the flat outer surface of the belt needs to be parallel to the surface of the pulley (and hence the rod). This means that in practice the pulley on the motor and the pulley on the axis rod need to be perfectly in line, so that the edge of the short belt remains parallel to the wall of the printer - but not touching it.

 

[gr5 2,004]

Just to clarify. Your UM came with 4 long belts and 2 short belts. The 2 short belts connect to the stepper motors. These short belts have twice the torque on them and twice the possibility for errors and are twice as hard to get to and twice as hard to see (dark back there) and twice as easy to forget about.

Get those short belts away from the plywood. Even .5mm is plenty but if they touch the plywood it's trouble. And make sure the belt is straight between the pulleys (pulleys are aligned so belt isn't crooked).