My printer is now printing..

Hi every one

I have now crossed a big milestone in my 3d printer project. I have started making the first prints on it. I began just over 10 months ago with no experience in 3D printers, and a Prusa style design I posted here on this forum. However, I quickly became convinced that a coreXY printer had much more potential. The idea of my design is that I should easily be able to change things, and that's obviously also needed

I would like to share my design here on the forum, even though it still has some challenges. I'm still proud of it, and I've invested a lot in it (not only time and money. thats the least).

The drawing:


My first and second print:


The printer as it stands right now:

The frame is not bad at all, but the idler pulleys would be much better aligned when supported from top and bottom.

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o_lampe
The frame is not bad at all, but the idler pulleys would be much better aligned when supported from top and bottom.

That is definitely my primary concern. However, I have not yet found the perfect way to solve it. Of course, I could easily make it with a square, hollow aluminum profile, but I'd really like a better way to tighten the belts when I'm already redesigning this part.

I'm considering designing something in plastic, even though I didn't want to use plastic for the vital parts of the printer.

It's hard to tell from the photo, but it looks like the belt segment that attaches to the extruder carriage on the lower left side isn't parallel to the X axis guide rail.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

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the_digital_dentist
It's hard to tell from the photo, but it looks like the belt segment that attaches to the extruder carriage on the lower left side isn't parallel to the X axis guide rail.

You're right. When I put it on, I did not place it right. However, I will take all the belts of this afternoon to tighten them, and I will put them back on the right way.

Are those steel core belts?

I tried putting steel core belts on my corexy mechanism and found that they require a lot of force to bend the belt around the pulleys (and I used 22 mm diameter pulleys). I didn't even mount the second belt and went back to the glass core belts I had bought for it, eventually replacing those with glass core belts made by Gates.

I have seen claims that there are some minimum pulley diameter requirements you have to meet for steel core belts to prevent core failure due to over flexing, but I haven't been able to find any manufacturer's design literature that spells it out for steel core GT2 belts.

I did use steel core belts in the Z axis, with a 22 mm top pulleys and 36 tooth drive pulleys. I'm not too worried about it as the Z axis motion is slow and the belt only bends one way.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

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the_digital_dentist
Are those steel core belts?

Yes, they are steel belts and they are terrible. They must be stretched with so much force that my fingertips hurt for hours afterwards. I can not recommend them for this purpose.

Unfortunately they were the only ones I had when I put the belts on, but I have already ordered 5 meters of fiberglass belts.

It looks like you're getting pretty good print quality, so they can't be that bad. I think you'll find the glass core belts a lot easier to work with.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

No, not bad like that, but even though they are quite tight, you can still see a bit of flexing when moving. I can also hear some audible clicks from the belt as it moves around the pulleys of the motors, after I tighten them. Most likely, the steel core is broken somewhere inside the belt. But I have to say that the quality came to an entirely new level as the belts were completely tightened.

How do you tighten the belts? I used sliding motor mounts and it's pretty easy to adjust/set the tension.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Right now, I tighten it by first loosening the front pulley mount, on the right side. Then I cut the strips on the right side of the extruder carriage and tighten the belts. It's a bit difficult, but it works for now. However, as I said, I'm looking for a better method. Can you link to a picture of your solution. It sounds interesting.

Both A and B motors are mounted this way.





Extruder carriage belt clamp (yellow):





I cut the belts to approximate length, attach one end of each at the extruder carriage and loop them through the motors and pulleys, then attach the other ends at the extruder carriage. Tensioning the belts is done by pulling the motors and screwing the motor mounts down tightly. The motors can slide 10mm so I can take up to 20 mm of slack out of the belts. I considered fancier mechanisms to tighten the belts but it is something that should only have to be done a few times during the life of the printer. There's not much point in putting too much effort there.

One could tighten the belts by using long screws to hold the belt clamps at the extruder carriage, but as the clamps are designed, you'd be tightening both belts at the same time- not always desirable. You'd also have to get a tool in between the belts to access the screws, not very convenient...

Edited 3 time(s). Last edit at 11/19/2017 11:40AM by the_digital_dentist.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Just a little update on my printer.

My pulleys on the gantry had already begun to bend, so I've reinforced them. It has not yet happened on the front pulleys, but they are still on my to-do list.

Right now, I'm concentrating on designing a new mount for my hotend. I had discovered that there is a very small amount of play in my linear rails on the x-axis. There is also some play on the y-axis rails, but this completely disappears because of the rigid gantry. I'm not so lucky with the x-axis. My experience is that the cheap mgn12 clones from China are somewhat shabby. On the other hand, I am positively surprised by the openbuild wheels on my z axis, and I want to use this system on my x-axis. They are very smooth and I have great control over how much load there should be on them. But I can not recommend the cheap Chinese clones here either. I have tested wheels from two places and they are poorly manufactured. However, I had already decided to use openbuld because I have a local retailer that has very reasonable prices and there is not much to save on the chinese compared to the originals, so that's not a problem.

I have also ordered two trinamic drivers for my x and y axis, which hopefully will reduce the motor's "talk".

Right now I can print between 60 and 80 mm/sec if it has to be high quality. If I go up to 100 to 120 mm/sec I can start to notice a slight deterioration in quality. But I'm happy with so far.