polymorph

Well, I feel like a fool. I bought a one pound can of the same green grease that came with my Ultimaker. I have applied it to the rotating rods (with the sintered brass bushings) and on the Acme thread Z axis. I have not printed in a few months, now I find that I can barely move the X and Y axis by hand. Touching the rods, the grease has become a sticky coating. I'm going to clean it off and put some dripless oil on it. I think it may have reacted with the oil in the sintered brass, because it has not done this on the Z axis threaded rod nor on the linear bearings, which I had very lightly greased.

Yeah, there are definitely better belts out there. Not my field of expertise. Anyone have a link to a good website or webinar or something similar where I can learn more about the differences?

I know I am not willing to give up the speed. I'm still in the process of tuning mine up and making improvements. I have Bertho's ball bearing pressure plate upgrade and have turned my speed up to 100mm/sec. It flies! Had some of OlyMEGA over last weekend, they are all familiar with the Prusa Mendel machines and were very impressed with the Ultimaker's speed. At some point I am going to make this mod, too, and get rid of the short belts. I can hear a ticking sound in the rear left top corner, I think it might be the short belt riding up on the gear pulley teeth and snapping back down.

That is a ballscrew and nut, all right!

Ah! Yes, that is precisely the problem. You may have been looking at Acme thread, also, not ballscrews. Usually just the nut for a ballscrew is $35 or more.

For speed, low pitch is better. A two-start 5tpi would be better than a 12tpi single-start, or worse allthread at 18 or 24tpi. Right now, a single revolution of the stepper moves it, what, a few inches? I don't have my Ultimaker in front of me so I can't measure diameter/circumference. So already a 5tpi ballscrew would require the stepper to move 5 to 10 times as fast for the same speed. Might have to upgrade the steppers, drivers, and power supply for that. Ballscrews are spendy... $35 is pretty cheap for that length of ballscrew and nut.

We could replace the long belts with something less stretchy. There are higher quality toothed belts with less give, I'm just not sure where to find them. Ballscrews or acme thread could replace the long belts, but it would take two for each axis. It would change things a bit in terms of the driver PCB, although it could be done as an add-on. I think it would be a rather significant change. Speed is an issue, so I don't see hardware store allthread being a solution, however I've not run the math.

The hobbed gear is now available from Portland, OR: http://store.trinitylabs.com/hobbed-pulley-by-blddk/ Hobbed bar shaft, may fit Ultimaker but ships from somewhere in Europe so shipping may kill me. He also makes Makerbot-style hobbed pulleys, with a variety of hole sizes: http://shop.arcol.hu/item/hyena

Hm... what the heck did I use, then? No sarcasm, I believe you. I don't recall what I used.

I bought TurboCAD 18 Deluxe 2D/3D last year, then I moved on short notice. I've finally gotten to play with it a bit with my Ultimaker in mind. I learned AutoCAD (aging student, went back to school about 4 years ago) but only 2D and have not had any opportunity to play with it after my one year free student licensed version ran out. So... there are some cool things missing from the <$100 Deluxe, but it does do a lot. I'm still trying to figure out the ins and outs. It can export as SketchUp SKP files, then from there I export as STL. The Pro version will export directly as STL but costs quite a lot more. But I'd be happy with that workflow, once I figure out what I'm doing in TurboCAD.

It looks like Makerbot is dropping all their parts for people building/upgrading their own 3D printers. Everything but a complete Mk7 head and one other item is out of stock, and is findable only via Google. So I'm hoping someone else starts making those drive pulleys. There was an IndieGoGo project that ended in June, he calls them "Hyena". Also sells a shaft threaded on both ends with the grooved drive area cut into it, looks made for Ultimaker. Haven't checked the sizes.

Regarding reversing the stepper - swap the wires between the A and B drive coils, it runs backwards. Or just reverse the two wires of one of the drive coils. Again, it reverses. http://www.nmbtc.com/step-motors/engine ... uence.html I see someone found that their RepRap feeder motor reversed just by reversing the plug. A bit risky if you don't check and confirm the wiring first. http://www.nmbtc.com/step-motors/engine ... uence.html

I have found that simply heating it up to 220 and leaving it there for a half hour or so, all the PLA runs out the end. Then it comes apart easily while hot, and PLA dissolves in Acetone, or as suggested wipes up with a Qtip while still hot.

What did you find out? Did you solve the problem? Have you been cleaning out the knurling on the drive bolt regularly? Get a stiff steel wire brush and scrub it out. I have found it is a very fine line between too tight and not tight enough on the feeder. Too tight, it grinds into the plastic pressure plate too hard and the teeth in the bolt grind a flat in the filament. Too loose, it also grinds a flat in the filament. Once it starts grinding, it fills the knurling and it is more likely to slip and grind in again. Unfortunately, as filament diameter changes, the screw settings must change. But it'll stay stuck on the flat part ground out unless you also push the filament in -really- hard while it is feeding, for long enough to get past the flat spot. I printed an upgrade that replaces the plastic pressure plate with one that includes a ball bearing. However, the same problem is there - no spring pressure, so even slight changes in filament diameter mess it up. The ball bearing just allows you to set the pressure even higher. But I'm an hour into a 2.5 hour print job, I don't want to quit and start over, so I'm riding herd on it. The "knurling" on the bolt is just too sharp. It tends to grind into the filament. Then if you don't immediately clean out the knurling, it begins slipping and grinding much more often. As far as variations, I'm still using the roll of white that shipped with my Ultimaker. I also think having only one point of contact with the drive to the filament is a problem. A lot of stress on the plastic right there. I like the half-round non-sharp feeder wheel someone was making. But I think rather than a non-drive wheel pressing the filament into it, I'd like to see -two- drive wheels pressed together. In fact, I'd like to see a drive with four wheels - two sets of two drive wheels. Perhaps the first drive wheels have a clutch and attempt to spin a little faster. Or just a DC drive motor, the amount of current regulated to set up a pre-tension pushing the filament into the stepper-driven drive wheels. Like what happens when I grab the filament and push it into the feeder mechanism.

My laptop is suffering from Windows rot. My netbook connected without problems (cross finger, knock on wood) and printed a new ball bearing pressure plate. Next I think I'll print both of the parts you mention so I can use the 6mm/4mm tubing I bought. I also discovered that my temp was far too low (210C) and now have it at 230C. I did find that I need to print the outline 6 times to prime it properly, as it tends to dribble when just sitting there hot before the print. I also bought a digital micrometer good down to one micrometer, it works better for this than my digital caliper to measure the filament. Also, the pressure on the feed bolt is somewhat sensitive, in that too much causes too much friction on the pressure plate, so there is a relatively narrow range of pressure that is just right. I have other ideas to talk about but I should not take this too far off topic.