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Posted · Fixing Pulley Innacuracy

@foehsturm Thanks.

I am just guessing that it might be cheaper to make them in the U.S. because from my past experience, stuff like this has always been significantly more expensive when it is made and shipped from Europe. Obviously, that might not be true in this case.

For anyone that is interested in my background related to machining...

Professionally I have been working as an applied physcist in bio-medical instrument development in the San Francisco Bay Area. I don't generally do very much machining myself, but have a fair amount of experience designing parts and getting them made.

 

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Posted · Fixing Pulley Innacuracy

I've worked with drawings and had parts made in the past. If you wish to share the drawings with me, I can certainly get some quotes. Or, if you prefer to manage this project on your own, I would suggest using a service like MFG.com. I've used them many times in getting machine quotes for many (aluminum) parts I have had custom made in the past. You can specify a country/region, etc. I was impressed with the 70 or so quotes I got on my most recent project. Hope that helps!

 

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Posted · Fixing Pulley Innacuracy

I had been watching this thread for some time till the last October, thinking I missed the second batch, thus for good.

Now I need to post this to get me in line whenever the next batch is possible. I've made numerous mods and the X-Y accuracy is less than 0.5% off, but there is reasonable friction when manually moving the carriage. In order to overcome that issue, I increased the current for the stepper motors, thus makes the machine louder. There are few problems such as visible Z-wobble even with the z-coupler replaced..

In short, put me on the list for the next batch. And I live in Korea, not north.

 

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Posted · Fixing Pulley Innacuracy

I haven't forgotten about this. I have just been too busy to think about it. If someone else wants to take up the cause of making them in the US, that is fine with me. Otherwise, I probably won't get around to doing anything about this until March. Currently we are in the middle of moving to and remodeling a new home, which is taking up all my attention.

 

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Posted · Fixing Pulley Innacuracy

I did notice that GT2 pulleys are available for about the same price as the custom pulleys foehnsturm is selling. They might not be quite as good quality, but at least they use a pair of set screws. I have seen some reports that they are good, but you would need to get GT2 belts to go with them.

 

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Posted · Fixing Pulley Innacuracy

@foehnsturm

 

Do you still sell those pulleys? Are there any available at the moment?

If no, do you plan to create another batch soon?

 

I like to order a DirectDrive - Set ... ;-)

 

Thanks for your reply.

 

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Posted · Fixing Pulley Innacuracy

For those of you that consider going for GT2. I just bought a set of 8 together with 5 m och belt for 64$ including shipment.

They were of high quality and the goods arrived in less than three days.. Just fantastic..

Here's the link...

http://www.ebay.ca/itm/8x-GT2-Pulley-and-5m-GT2-open-Belts-for-Rostock-reprap-prusa-mendel-cnc-/161203740567?ssPageName=ADME:L:OC:GB:3160

I also ordered material for new axis and plan to make a direct drive. I will mill down the rods to the dimension needed and then make a couple of details that can fit to the axis and still make use of the bearings in the original places.

The pulleys cannot be made to fit an 8 mm axis. However, I would consider contacting the guy and ask for pulleys that fit 8 mm axis. I think he can do it... and it will not be crap. These I recieved were high quaility machined ones. I'm very pleased.

I measured the pulleys I recieved and they were within +-0.01 in tolerance.. I'm happy.. :-)

Perhaps he has MXL ones as well.. Worth asking...

GT2 pulleys and belt

 

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Posted · Fixing Pulley Innacuracy

@foehsturm I would also like a set of pulleys.

Please let me know when the new set might be available, and the details.

I just love the all these options to make the printer better.

Well until the Ultimaker goes all skynet, and starts to auto-upgrade itself.

 

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Posted · Fixing Pulley Innacuracy

One source of a clicking belt noise is misaligned pulleys. The belt gradually runs up on the edge of the pulley and then snaps down again.

The second one that I have been trying to trace down is a pitch error between the belt and the pulleys. Gradually the belt and pulley gets out of alignment and then it snaps back into the grooves. For example if the belt pitch is 2.5mm and the pulley is 2.5mm. It would happen if the pulley is a little bit too large or too small.

Bertho

 

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Posted · Fixing Pulley Innacuracy

After I had a http://umforum.ultimaker.com/index.php?/topic/3828-nasty-displacement-solved/, I changed to direct drive and reasonable long belt adjustment. However, There are still sometimes appearances of backlash in my prints. I realised that the printhead cannot be moved with the same force at any position. Differences in the required force are actually quite high.

So I came along to disassemble all the x and y rods today and measured the pulley accuracy with callipers. Here is what I got:

Ultimaker Pulleys 8mm measured

The numbers show the wall thickness at the widest and the narrowest spot, e.g. '60' means 4.60mm. I assume the outer diameter is quite constant (I checked some and it seems reasonable to assume this). So the difference in wall thickness shows the off-center-distance of the 8mm bore.

Has anybody done something similar with his original Ultimaker pulleys? What do you think is a reasonable accuracy in therms of off-center-distance?

Next thing I'm going to test is the straightness of the rods.

 

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Posted · Fixing Pulley Innacuracy

Nope, not reasonable...

I have made the same observations but not in the same way. I put each pulley up in my lathe and watched them. On one hand I just clamped them into the chuck and looking at the center hole - how much it moved. Secondly, to really reveal the truth I put them up on a fitting shaft and then looked at the cogs moving. They are not well made. They are off center and the outer pieces that are pressed onto the center part (the cogs) are not centered either. However, the outer parts to not matter but the off center of the through hole matters. On top of this - the through hole is to big so the pulleys will be off center when attached to the shafts.

I have now bought new GT2 (5 mm) and drilled them to close to 8 mm and the last part I sanded to get the perfect fit.

 

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Posted · Fixing Pulley Innacuracy

I know, I didn't keep my promises :mellow:

I would have to let them manufacture at least 200 pieces to get a reasonable price.

So let's do a quick poll.

Who would order at set (approx. 80 € + tax for a set of 12)?

 

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Posted · Fixing Pulley Innacuracy

Hi I am interested too but only for a set of 8 since I have converted to direct drive.

Where will they be shipped from?

Bertho

 

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Posted · Fixing Pulley Innacuracy

Hi:

Are these pulleys only useful of UM original?

Doe UM2 suffer the same problem?

 

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Posted · Fixing Pulley Innacuracy

Are they supplied with belts, or do you need to buy those seperately? It seems an intersting upgrade. I understand why the pulleys cost what they do, bu the price is somewhat prohibitive.

 

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Posted · Fixing Pulley Innacuracy

If you use them to swap out bad pulleys on an original Ultimaker, you can keep your original belts. They are a direct deplacement, just on a hugely improved quality (and therefore cost) level.

You only need new belts if you get pulleys that have a different diameter (don't do that, it will most likely not fit into the Ultimaker...) or if they use a different geometry (for example GT2 instead of MXL).

Buying GT2 belts and pulleys can be a cheaper alternative. But there are good and bad GT2 pulleys just the same way it is with any other system...

 

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Posted · Fixing Pulley Innacuracy

As I look at GT2 pulleys the prices of the pulleys discussed here are not even that much higher, though I have not looked around extensively. With a concurrent direct drive upgrade the cost can be limited as only 8 pulleys are needed.

That just leaves that I find it hard to judge just how much of an impact this upgrade should make. I did notice soms nonlinear resistance when moving the printing head manually and I feel this could be caused by the pulleys. No clue how much of an impact this has on printing quality.

 

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