RE: VFA Artifacts on X+Y Straight Edges
Plot twist! The spare PC-CF idler mounts that I printed ARE now strong enough to stop the nut from turning. I assembled one, but evidently didn't get the nut centred in the hole, and the screw bound up very quickly. I should have stopped, but thought dammit, it's only a spare, so I kept going. When I attempted to undo the bolt, it sheared off before the nut started spinning.
This is with the downloaded model that has the little voids either side of the nut slot, making it effectively 100% infill just there. Mt settings were 4 perimeters, 40% cubic, 0.15 Structural.
Maybe the best approach in the case of binding, if you've already fitted one of these downloadable mounts, is just to shear the bolt off - it'll be a lot easier to get apart after that!
RE: VFA Artifacts on X+Y Straight Edges
I plan to dab some anti-seize on the screw next time I have the belts loose in hopes of preventing a problem from developing.
Purple Loctite during assembly between the stainless nut and the stainless thread
I'm confused now -- lubricate the threads, or glue them in place? 🤔
I can see pros and cons with either approach. Lubrication (which I assume is what "anti-seize" is?) should prevent the nut & screw from seizing up permanently -- but may cause undesired loosening of the belts under vibration? Weak Loctite should stop undesired movement, maybe also helping against the threads seizing under friction -- but if you have to tighten the tensioners because the belt stretches over time, things will probably get messy after the second re-tensioning and re-Loctiting?
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Purple Loctite during assembly between the stainless nut and the stainless thread
That's a thread locker isn't it? Won't that make future adjustment more difficult, or is there something about the purple that stops it setting? I would have thought a smear of grease would be all that's needed.
RE: VFA Artifacts on X+Y Straight Edges
Purple Loctite during assembly between the stainless nut and the stainless thread
That's a thread locker isn't it? Won't that make future adjustment more difficult, or is there something about the purple that stops it setting? I would have thought a smear of grease would be all that's needed.
Purple Loctite is an anti-vibration non-thread locker. So it’s use is keeping things from seizing and keeping vibration from causing things to get loose.
RE: VFA Artifacts on X+Y Straight Edges
Ah ok - sounds ideal then.
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Proof of concept (in ABS) for a heat-set threaded insert. It seems to work ok. Tricky to get the insert in straight from the pulley side, but that's the better side to use as it's quite unlikely to pull through under tension. I left a shoulder on the screw side for the insert to rest against. I used a long screw to correct the alignment while the plastic was still soft. It pushes a bit of material up above the insert during insertion, and although there's still plenty of clearance for the belt I'll aim to push that down next time while it's still soft.
I'll tweak it a bit to make the insertion easier to get straight, and then blow a bit more PC-CF on a couple of them. Hopefully it'll mean I can then forget about the modified mount.
RE: VFA Artifacts on X+Y Straight Edges
Nice
RE: VFA Artifacts on X+Y Straight Edges
Purple Loctite is an anti-vibration non-thread locker. So it’s use is keeping things from seizing and keeping vibration from causing things to get loose.
We are talking about Loctite 222, right? That is a thread locker, just not a very strong one one, easily broken with hand tools.
You are supposed to apply it onto the threads right before assembly (so it penetrates the thread surface). Then you have 10 to 15 minutes of curing time, during which you have to set the belt tension. Once cured it should prevent the nut from shaking loose, and hopefully from eating into the screw threads and permanently seezing as well. All good that far.
But how would you proceed if you have to re-adjust the belt tension? Once you break the Loctite layer (which should be easy with the standard hex key), it will not re-cure. You would have to loosen the screw to the point where you can reach the thread to re-apply Loctite. And you probably want to try and clean the old stuff out of the threads since otherwise everything gunks up after the second or third cycle.
Maybe we can come up with a mechanical solution to lock the tensioner screws in place instead. How about a little stopper plug with a hex "pin" that you push into the screw head after setting the tension? But there is no obvious way how the plug could get a hold on the frame to stop it from rotating. And it would have to stay within a low profile so it does not interfere with the door. Hence I don't have a proper design idea yet.
RE: VFA Artifacts on X+Y Straight Edges
I've fitted a couple of the brass insert idler holders. With the tweaked design the insert now sits square in the mouth of the pocket, so just needs pushing in with heat. I printed them in PC-CF with 100% infill, and the inserts are surprisingly hard to push in, compared to ABS and PETG.
I was able to tension both sides very easily (the Gates Carbon app that people are recommending really does work rather well), and hopefully I can now forget about a seized tension adjuster.
RE: VFA Artifacts on X+Y Straight Edges
In case anyone else wants to go this route, I've published the model here. It's maybe a bit premature, since I don't have many prints under my belt with it yet, and I don't know for sure that it solves the galling issue, but it's there if you want to give it a go.
RE: VFA Artifacts on X+Y Straight Edges
My posts are all labeled *Awaiting moderation* for so long, my post becomes irrelevant, since the subject changes.
RE: VFA Artifacts on X+Y Straight Edges
Purple Loctite is an anti-vibration non-thread locker. So it’s use is keeping things from seizing and keeping vibration from causing things to get loose.
We are talking about Loctite 222, right? That is a thread locker, just not a very strong one one, easily broken with hand tools.
You are supposed to apply it onto the threads right before assembly (so it penetrates the thread surface). Then you have 10 to 15 minutes of curing time, during which you have to set the belt tension. Once cured it should prevent the nut from shaking loose, and hopefully from eating into the screw threads and permanently seezing as well. All good that far.
But how would you proceed if you have to re-adjust the belt tension? Once you break the Loctite layer (which should be easy with the standard hex key), it will not re-cure. You would have to loosen the screw to the point where you can reach the thread to re-apply Loctite. And you probably want to try and clean the old stuff out of the threads since otherwise everything gunks up after the second or third cycle.
Maybe we can come up with a mechanical solution to lock the tensioner screws in place instead. How about a little stopper plug with a hex "pin" that you push into the screw head after setting the tension? But there is no obvious way how the plug could get a hold on the frame to stop it from rotating. And it would have to stay within a low profile so it does not interfere with the door. Hence I don't have a proper design idea yet.
The other possibility is to use actual anti-seize…
But you are correct that is the Loctite that you should use…. And once it’s in the threads, even if you loosen it, it will remain in the threads. Which effectively means it’s going to prevent any sort of galling. Honestly, it’s a lot better of an idea than probably using anti-seize, which is quite messy stuff.
222: https://www.amazon.com/dp/B012A4USS2
verses:
https://www.amazon.com/dp/B000HBM8HU
https://www.amazon.com/WEICON-Anti-Seize-Ceramic-Paste-Metal-Free/dp/B0CZT8K2ZR
RE: VFA Artifacts on X+Y Straight Edges
I have some Locktite 222 on hand that I use on spoke nipple threads when building bicycle wheels. It would probably be fine here in a small quantity. I expect grease or anti-seize would be fine as well. I bet there is enough friction in there when tensioned to keep them from backing out during normal use. The need for locking in bike wheels is due to the possibility of the tension being removed momentarily during hard hits to the wheel. This tensioner is under consistent tension at all times, never going into a relaxed state.
The garage is fairly warm this afternoon, but since I actually have time now I may go dig into figuring out what's making the tick tick sound, and lube the tension screws while I'm at it.
-J
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My posts are all labeled *Awaiting moderation* for so long, my post becomes irrelevant, since the subject changes.
I feel your pain. Frustratingly, when quarantined posts are released they appear in sequence at the point they were submitted, and I don't think they flag up as new posts, so can get overlooked. For example, @DGT's post about the better square nuts has some good info, but passed me by until just now. The only solution is to keep posting regardless, until your quarantine threshold is reached.
RE: VFA Artifacts on X+Y Straight Edges
Anti-seize doesn't really lead to loosening - it requires adjusting torque settings (not applicable here) and helps prevent galling. I suspect it's the right solution, if miserably messy. There's enough tension I expect it to hold.
I just so happened to need to change spark plugs today so even know where my anti-seize is now. Soon as I have some time I'll give it a try. This weekend was spent patching drywall and chasing an elusive misfire rather than tinkering.
RE: VFA Artifacts on X+Y Straight Edges
This Anti-seize seems like a solid tip for new players. I'll be ordering my kit in the next couple of weeks and, now that I've learned this is a thing, will be sure to have some of this on hand for the assembly.
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Anti-seize doesn't really lead to loosening - it requires adjusting torque settings (not applicable here) and helps prevent galling. I suspect it's the right solution, if miserably messy. There's enough tension I expect it to hold.
I just so happened to need to change spark plugs today so even know where my anti-seize is now. Soon as I have some time I'll give it a try. This weekend was spent patching drywall and chasing an elusive misfire rather than tinkering.
I agree. The more I thought about it the more I didn't want to use the purple locktite for this. In this context I think the most important thing is to keep things moving smoothly and not deteriorating slowly with wear or corrosion. There is still friction in the bolt head that will keep it from backing out, but the threads will be far more protected by a touch of anti-seize. I ended up removing both tensioners, gently pushing the scratchy feeling square nut out of the pocket and installing a new smooth one into the OEM tensioner. I touched each screw with a bit of anti-seize and rubbed it down into the threads before wiping away all of the excess. They went in without any ugly transfer, and both of my tensioners feel consistently smooth with an appropriate amount of friction.
During the job, I pulled the RH motor out to check clearances on the pulley, thinking that something might be rubbing (causing the noise). Everything there looked good and while it was out I exchanged the OEM pulley for one of the Mellow pulleys linked earlier in this thread.
The tick tick sound is still there though, and I now believe it is likely noise from one of the idlers on the RH end of the X rail. I'll do some more experimenting to confirm this and if I'm able to, I'll reach out to support to ask if they'll send me some replacements.
Meanwhile, the printer is operating great, aside from the subtle belt ripple and tick ticking. I'm receiving some 3DXMax (real) PC this week for testing, and I'm looking forward to trying some test prints with yet another "new" material that was previously out of the question with my open Mk4S.
-J
RE: VFA Artifacts on X+Y Straight Edges
This Anti-seize seems like a solid tip for new players. I'll be ordering my kit in the next couple of weeks and, now that I've learned this is a thing, will be sure to have some of this on hand for the assembly.
Yeah, when I first started reading about the spinning nuts my first thought was 'oh, mine works fine, so you must be doing it wrong!'. But then it happened to me, on a previously smoothly functioning tensioner, and that changed my perspective of course 🤣
I guess the new belt tensioning advice, that puts the belt tension higher than it used to be (from 85Hz to somewhere over 100Hz if measured at the original position), may well contribute to an increased number of cases. That increase in frequency equates to about a 50% increase in the tension force on the adjuster (according to ChatGPT 😀 )
So lube those tension screws! If your belt tension is ok, don't touch them, but the next time you need to adjust belt tension, make it the first thing you do - gradually, and evenly, release the tension on both sides so that the tension screws can be removed and lubricated.
RE: VFA Artifacts on X+Y Straight Edges
May I suggest that we continue the "seizing tensioner screw" discussion in a new thread if there is more to be said? It's off-topic in the VFA/belt ripple thread.
RE: VFA Artifacts on X+Y Straight Edges
May I suggest that we continue the "seizing tensioner screw" discussion in a new thread if there is more to be said? It's off-topic in the VFA/belt ripple thread.
Completely agree - sorry! I'm done now! I was side-tracked - I didn't want to try any more compliant pulleys until I was happy that I wasn't going to have to get my Dremel out again to fix a seized adjuster.