Folgertech Prusa i3 prints leaning tiny bit, and new hot end question

Good afternoon, and thanks in advance for your time. I am relatively new to the world of 3D printing, but I love to tinker with things. I am very mechanically inclined, and I love RC flight, so building a printer to make my own parts sounded like a win-win. I went with the FolgerTech acrylic Prusa i3, and it has been a lot of fun so far. I have had minor problems with it here and there, and I've been throwing upgrades at it to try and chase things down. I have solved everything except one: as things get taller, they start to lean forward ever so slightly. Every 30 or so mm in height equals about 1-2mm of forward lean, always in the direction of Y home. Because the lean is so slight, it is definitely not the belt skipping, nor the Y drive pulley slipping, and certainly not adhesion. Sometimes the lean is so minimal, I have to use a carpenter's square to confirm the part is leaning. The bed is dead level, and I can print single layer sheets that are smooth as glass and thin as window tint.

So far I have replaced the acrylic bed with a solid aluminum bed, new RAMPS board (old one literally smoked and the heated bed stopped working), replaced all the printed pulleys with aluminum GT2 pulleys, replaced all the zip-tied slide bearings with screwed-down-metal-housed bearings, and swapped out the extruder / hot end for an all metal MK8 unit. At this point, my next step (unless someone here has a better idea) is to swap out the bed motor and stepper driver. I honestly don't know what else it could be. I have replaced every other related moving part, and tried many different designs and slicers. If you guys do think it is the motor, I know it is a Nema 17 4.8kg motor, but is it 1.8 dps, or .9 dps? I'm assuming 1.8, but I've seen both used on other machines.

Second question, and I apologize if it has been asked before. A friend of mine gave me an E3D V6 hot end with Bowden fitting that he wasn't using anymore. I know there are advantages to both direct drive and Bowden, and plenty of reasons to go in either direction. Just for the sake of me playing with things and experimentation, can I simply remove the hot end from my MK8, insert a tube attachment where the hot end should be, and then use that to feed filament to the E3D? All of my firmware and settings are currently configured for direct drive and the gears / feeding assembly I already have, so in theory, do I have to change anything else? If it is as easy as making this mount (http://www.thingiverse.com/thing:547706), and buying a piece of tube and one Bowden fitting, I'm in!

Thanks for any and all help you can provide for both questions!

Hi,

I am probably the worst to give advices. I don't have my first print yet and I still in components acquisition stage.... but here is my opinion (or what I would do) regarding the Y axis issue:

I would do a stress test moving the only the Y axis and keeping the Z-X in the same position to be sure that the issue is only in the Y axis. For example moving 10cm forward and going back in Y direction 100 times and see if there is any difference between the star and the end position.
If it works right, you can check if the structure is properly assembled and the screws fixed.
I you can see the issue then I would check the next:
- Check the voltage reference in Y-driver. (To avoid skipped steps)
- Check that the Y-pulley is properly fixed to the Y-motor axis. (tolerance in the movement)
- Check that your Y-belt is in good conditions and it moves smoothly in both directions.

May be you already did those things. Anyway good luck!

Thanks for the advice, I'll check the voltage on the stepper driver before I replace it. I was going to do a similar Y axis torture test last night, but I ended up having to work late... going to try tonight. Plan is to print a 100Lx10Wx40H "wall". I want to print it perpendicular to the Y axis the first time, so Y barely moves, and see how bad the lean is. Then I'll print it again turned 90 degrees, so Y is working like crazy, and compare the lean again. I expect the wall that prints in line with the Y axis to be worse, and hopefully that will verify that it is the motor or driver. Forgot to mention in the last post that I'm only printing at 40mm/s, so it's not like I'm slamming the poor thing around expecting miracles lol.

As for the rest, the pulley on the Y motor is totally solid with zero wiggle, the belt is brand new, the idler pulley is a brand new all aluminum piece with fresh bearings, and the whole bed glides smooth from end to end.

**if anyone has any input regarding using my existing MK8 to push filament through a Bowden tube, I'm all ears!

my guess would be that you have a structural problem somewhere, which is the best type of problem because structural problems are easy to find and fix. check that your frame is square, and sitting on a level surface. Make sure that your smooth rods are straight, and held in their slots firmly. And make sure that you threaded-rods/leadscrews aren't so bent up or otherwise screwy that they are interfering with something else.

I have also heard of people having issues with end-stop sensors being triggered by interference/noise on the lines. This manifests its self much as you have described, but your going to have to google to figure out how to fix it/determine that it is actually the problem. I have never seen this issue my self.

Good call, thanks, I'll check all corners side to side and top to bottom. The printer is sitting on a slab of granite, so I know it is mechanically level, but I suppose that doesn't mean the acrylic frame is actually square. Just because it doesn't wiggle or wobble doesn't necessarily mean it isn't out of whack somewhere.

PS, I went to my local stone cutter shop where they make granite countertops, and I picked up a sink cutout for $5. This is a scrap piece that they consider a throwaway, and they were glad to sell it to me. The surface is dead smooth, it'll never warp, and it is plenty heavy enough to absorb vibrations from the machine. I stuck a fistful of little silicone feet on the bottom, and now it doesn't matter where I put my printer, it'll always be solid.