My custom D-Bot
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I've flat spotted some Delrin wheels. Swapped all 20 to the polycarbonate 'tyres' when I bought a further eight to add a second set of z-axis guides to the front of the machine. Had no problems that I am aware of since.
This was on a core-xy using four wheel guides as per standard build instructions. I think I'd pinched one pair up too tight against the rail.
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That would certainly do it (having them too tight). I have to say that before I started printing my own gantry plates, I bought a couple of OpenBuilds ones and found that even with the eccentric spacers backed fully off, the wheels were too tight on the rails. I got around it by opening up the smaller hole in the gantry plate which gave me a bit more adjustment.
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I think I've isolated the source of my micro vibration patterns showing most visibly on lower layer heights. It's hard to get a good picture of it, but it looks almost like ringing patterns, except that it doesn't follow the same edge pattern, it's more distributed and random looking.
Normal ringing pattern:
Vibration ringing pattern:
I have been trying to use the formula provided by @dc42 here to eliminate the ringing. I was able to clear up the X axis, but wasn't able to remove it from the Y axis direction.
Then I started to hear a rather loud cracking sound. What's that sound?
In the video you'll hear what sounds like intermittent snapping plastic. When this started I stopped trying to fix the vibrations and started to find out where the awful sound was coming from. I couldn't see anything broken in the carriage. The wire loom wasn't the source (I took it off).
Then I disconnected the belts and moved the carriage by hand. Movement on the X axis was definitely not smooth. I tested rolling each wheel and discovered that the top wheel was very stiff and when I moved the carriage quickly I could reproduce the sound. I swapped out the top wheel with one of the spares and the sound went away and movement feels smooth again. The bearing of the wheel had exploded and leaked black lubricant
However, the Y axis still has some vibration and I think one or more of the polycarbonate wheel bearings are also failing. I bought a few extra expecting some failures, but didn't expect them this soon.
X before:
X After:
But the Y side always looked something like this:
I'm now torn over whether I should just go back to the delrin wheels and let them deteriorate or get something like the openbuilds delrin wheels. https://openbuildspartstore.com/delrin-mini-v-wheel-kit/ If only they weren't so expensive! 7USD per wheel. The polycarbonate wheels on ali express were 40 for 16$!! Get what you pay for though I suppose.
At least now I know the source of the problem and can fix it.
EDIT: Found a couple more bad bearings. At least it was only one per wheel so I was able to combine the good bearings and reinstall. Who knows how long they will last. Also surprised by the wear on the wheel. The failed wheels were all directly on the tensioner side. I suppose it's possible I had them over tensioned, but it's just an M3 screw finger tightened.
Now to see if the vibrations are gone in the print. The movement definitely feels smoother.
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Oooh, nasty. If it's any help, I've never had any probs like that with the genuine OpenBuilds ones (full size, not the mini). No bearing failures nor any signs of excessive wear. They are expensive though. I think I worked out that with two spaces (some eccentric and some plain) as well as shims, bearings nuts and bolts, they works out on average at about £9.00 a kit. My two X gantries each have 6 wheels (3 per rail but two rails) so that's 12 wheel kits. My Y gantries have 4 each and their are two pairs of Y gantries so that's another 16. Then I have 3 linear guides for the Z axis with 4 wheels per guide so that's another 12 kits making 40 kits in total. So over time, I've spent about £360 on wheels - more than a lot of people spend on a complete printer.
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@deckingman yeah you can definitely blow the bank at the openbuilds store but it does look like good quality kit.
I've replaced all the y axis wheels with delrin now and it's back to smooth. Almost half the wheels feel a little rough and some were very rough and no doubt on their way to the same loud failure.
Quite disappointed by this particular "upgrade". Too good to be true at that price obviously. At least I have the wheels and can replace the bearings. So not a total loss.
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Looks great. I have a heavily modified C-Bot (D-Bot wasn't around when I made it) and I really dig your z-axis leadscrew setup. Nicely done!
My stepper motor website:skysmotor.com
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Oh wow, just catching up. Those came with your PC wheels? Yikes. There are some on Amazon too, but I'm not sure how much better they'd be except probably easier to return if they're a mess, amazon pc wheels 20 pack. $3 and change per wheel might be worth checking out. I almost picked them up, but I'm still interested in the potential to use some of these guide rails I have laying around.
My kit was supposed to show up today, but I got off work today late today, and my wife decided she had somewhere else to be besides at home waiting to sign for my package(joking, of course)... so until tomorrow. I think just about everything else has shown up. I got my delta back up and running, so I'm starting to print parts tonight. I probably won't get to start actually building until this weekend though. -
@rosethia thanks. The z axis definitely took the longest to figure out. Pretty happy with it so far. One thing I might change is getting the idler tensioner plate milled out of metal. It can flex a bit as it is now. It was stiffer in PLA originally but the bolts had a tendency to migrate through and deform it. In PETG it's tougher but has more flex. I'm going to try ASA next. It that doesn't do it, polycarbonate.
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@ntgorilla sadly those wheels won't ship to me in Canada.
Good luck with your build. Let me know if you run into anything.
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@phaedrux I'm sure it's more a matter of when and not 'if'. I've already made one silly mistake from ordering parts at like 2 in the morning... forgetting about the v-wheels, I ordered some Misumi extrusions to make I a bit taller, and replace some of the 2020 with 2040... totally forgetting they're not v-slot. Oh well, just more of a reason to try out these rails. I've only really had time to clean up the extrusions that came in the kit and sort everything out... will get there eventually.
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@ntgorilla ouch. I think there are some DBot mods for misumi rails.
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Phaedrux, I have basically the same printer as you and I recently printed your remix of Sparreau's print carriage. I've been attempting to set up the BL touch and have seen some posts on the forum where you are helping people get theirs going. Could you help me out? Thanks
No such thing as spare time. No such thing as free time No such thing as down time. All you got is lifetime. Go!
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@phaedrux said in My custom D-Bot:
@ntgorilla ouch. I think there are some DBot mods for misumi rails.
I built a D-Bot once.
It lasted about a week after I completed the build.
I was not a happy camper, so I took it all apart and re-built into something quite different.
But I least I got to re-use some of the frame pieces.
Good luck.
Frederick
Printers: A FT-5 with the 713 upgrade bits, a custom MarkForged style, a small Utilmaker style, a small CoreXY from kit and a E3D MS/TC setup. Various hotends. Using Duets (2 and 3) running 3.4.6
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@gbusy24 said in My custom D-Bot:
Phaedrux, I have basically the same printer as you and I recently printed your remix of Sparreau's print carriage. I've been attempting to set up the BL touch and have seen some posts on the forum where you are helping people get theirs going. Could you help me out? Thanks
Feel free to start a new thread. The BLTouch comes down to wiring for the most part and config for the rest. If you start a new thread, show your wiring (and check it with a mutlimeter) and show your config.
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@fcwilt The Dbot in it's stock form is a product of the era. It makes for a solid base for modding.
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@phaedrux said in My custom D-Bot:
@fcwilt The Dbot in it's stock form is a product of the era. It makes for a solid base for modding.
Yes it did.
I had a great time deciding what form the new printer would take. I went through four major design revisions before I settled on what I have now.
It would be hard to tell it started life as a D-Bot.
This is my "D-Bot" today:
Mark Forged Kinematics with Triple Z-Axis Belt Drive, Remote Drive Zesty Nimble Extruder and Slice Eng Hotend.
Do you have any long term plans for yours?
I hope you keep us informed of your journey.
Thanks.
Frederick
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@fcwilt said in My custom D-Bot:
Do you have any long term plans for yours?
Not really. I think it's reached its final form. Mostly. I've added a volcano hotend and updated the Z axis belt arrangement and Z motor mount to add some rigidity there. But as it is it meets most of my needs. I do have a Voron kit I need to get around to building once things settle down a bit more.
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@phaedrux said in My custom D-Bot:
@fcwilt said in My custom D-Bot:
Do you have any long term plans for yours?
Not really. I think it's reached its final form. Mostly. I've added a volcano hotend and updated the Z axis belt arrangement and Z motor mount to add some rigidity there. But as it is it meets most of my needs. I do have a Voron kit I need to get around to building once things settle down a bit more.
Is that the Voron machine with the fixed bed? I find that to be an very interesting design.
Frederick
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@fcwilt Yes it is. Voron 2.4.
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@phaedrux said in My custom D-Bot:
@fcwilt Yes it is. Voron 2.4.
I hope you keep us apprised of your progress with that machine.
Frederick
