PSA -- Tool change issues over time -- docks easily loosen
After having the XL 5 tool for a couple of months, I started having tool change issues on large prints, and it turns out that the docks can easily come loose after any significant use. When I installed them, I used the Prusa provided $0.15 2.5mm allen key and tightened them as much as I could with that tool. Let's cut to the chase, it wasn't enough. I am now recommending the following for all XL owners: 1) get a real allen key like this one for less than $5 Amazon Klein Tool 2.5mm Allen Key, 2) get a low strength thread locker like this one for less than $10 which is hand tool removable (55 in/lbs) Amazon Permatex 24024 Low Strength Threadlocker Purple, 6 ml Tube. No affiliate links.
Maybe some of you folks have a stronger wrist than I do. In any event, so far this seems like the weakest link in the design, I hope Prusa can come up with an improvement on our next tool upgrade. It's kind of painful to have multiple $30 print failures on a $5k printer over less than $15 of tools/parts (at retail prices).
Happy printing everyone!
RE: PSA -- Tool change issues over time -- docks easily loosen
I used Loctite 243 and used the included universal wrench as a cheater bar. Mine haven't come loose.
I also removed the honeycomb screen on the back to get better access.
RE: PSA -- Tool change issues over time -- docks easily loosen
Apart from the honeycomb I recommend to also disassemble (2*M3 T10) the dock cable router from the dock so that you get proper access to dock and its the single M3 with a (good quality!) 2.5mm allen key.
RE: PSA -- Tool change issues over time -- docks easily loosen
Hi @Tad,
I had the same problem.
I talked about it on the French forum.
You can take a look at the solution that I adopted and which has been working well for several months.
Sincerely
Prusa i3 MK3S Prusa XL 5 heads Dagoma Disco Ultimate bicolor Creality Ender 3
RE: PSA -- Tool change issues over time -- docks easily loosen
My thanks to @brian-12, @blauzahn and @rgb!
@rgb I used Google Translate for your article, my French is extremely rusty (haven't used French since 1986). In your picture, is that a new part you designed, like a standoff? Have you posted that on Printables? I love the idea of providing that support to the structure versus merely tightening the 3mm bolt.
Best,
Tad.
RE: PSA -- Tool change issues over time -- docks easily loosen
It's simply a small parallelepiped wedge made of PLA 😊 😊 😊
Prusa i3 MK3S Prusa XL 5 heads Dagoma Disco Ultimate bicolor Creality Ender 3
RE: PSA -- Tool change issues over time -- docks easily loosen
I'd also like to add, the combination of all three techniques, thread locker which also acts a lubricant, a stronger hex tool and taking off the back proved too much and I was a little over zealous and managed to strip at least one of the threaded holes in the aluminum insert. Very frustrating!
RE: PSA -- Tool change issues over time -- docks easily loosen
The bar with the 5 M3 threads is of the same 3mm thin cheap steel strip material with low yield strength like the inserts with M4 that keep the frame together. I do not like the fact that the non-centering M3 threads are supposed to position the heads at distance. Due to the meaningful press fit it is not easy to align them exactly at the precise distance, say, +/-0.1mm. I also do not like the fact that the axial positioning of the bar depends on the height of the head of the M4-screw connecting the horizontal profiles of the core-xy at the left side. The connection via the groove of the profile also has the tendency to pull out the lips of the profile slightly, even when the docks are fully inserted. I could slip in a 0.03mm strip into the formed gap. btw: The connections of the frame do have the same weakness.
Granted, on my machine this works so far. But the heads are supposed to do many thousands of tool changes on the XL whose key selling point is the tool changer.
RE: PSA -- Tool change issues over time -- docks easily loosen
I've heard of many issues with Loctite damaging plastics, specifically including 3D printed PETG, even with minor or indirect exposure. I'd be very careful.
I was never sure I got my docks in all the way, though they're lined up (after going back and tightening one of them up a bit more) and they haven't caused problems yet. This really seems like an undercooked part of the design.
RE:
I've heard of many issues with Loctite damaging plastics, specifically including 3D printed PETG, even with minor or indirect exposure. I'd be very careful.
I was never sure I got my docks in all the way, though they're lined up (after going back and tightening one of them up a bit more) and they haven't caused problems yet. This really seems like an undercooked part of the design.
The Loctite doesn't go on any plastic. It goes on the screw and threaded metal insert. You only need a small drop on a screw that small.
RE: PSA -- Tool change issues over time -- docks easily loosen
I've heard of many issues with Loctite damaging plastics, specifically including 3D printed PETG, even with minor or indirect exposure. I'd be very careful.
I was never sure I got my docks in all the way, though they're lined up (after going back and tightening one of them up a bit more) and they haven't caused problems yet. This really seems like an undercooked part of the design.
The Loctite doesn't go on any plastic. It goes on the screw and threaded metal insert. You only need a small drop on a screw that small.
And that screw goes through plastic parts, into metal parts that are near other plastic parts. Parts that are put under great stress by the installation process, making them even more sensitive to stress cracking and embrittlement by accidental contact or vapors.
RE: PSA -- Tool change issues over time -- docks easily loosen
I've heard of many issues with Loctite damaging plastics, specifically including 3D printed PETG, even with minor or indirect exposure. I'd be very careful.
I was never sure I got my docks in all the way, though they're lined up (after going back and tightening one of them up a bit more) and they haven't caused problems yet. This really seems like an undercooked part of the design.
The Loctite doesn't go on any plastic. It goes on the screw and threaded metal insert. You only need a small drop on a screw that small.
And that screw goes through plastic parts, into metal parts that are near other plastic parts. Parts that are put under great stress by the installation process, making them even more sensitive to stress cracking and embrittlement by accidental contact or vapors.
So don't get it on them. The amount of "vapors" from a drop of Loctite is of no danger to your plastic part.
If your worried then don't use it. To those who don't want the chance of them vibrating loose add a drop of 243 Loctite to the screw.
RE: PSA -- Tool change issues over time -- docks easily loosen
I've heard of many issues with Loctite damaging plastics, specifically including 3D printed PETG, even with minor or indirect exposure. I'd be very careful.
I was never sure I got my docks in all the way, though they're lined up (after going back and tightening one of them up a bit more) and they haven't caused problems yet. This really seems like an undercooked part of the design.
The Loctite doesn't go on any plastic. It goes on the screw and threaded metal insert. You only need a small drop on a screw that small.
And that screw goes through plastic parts, into metal parts that are near other plastic parts. Parts that are put under great stress by the installation process, making them even more sensitive to stress cracking and embrittlement by accidental contact or vapors.
So don't get it on them. The amount of "vapors" from a drop of Loctite is of no danger to your plastic part.
If your worried then don't use it. To those who don't want the chance of them vibrating loose add a drop of 243 Loctite to the screw.
"Just be perfect" is in general not good advice for working with a multi thousand dollar piece of machinery, and there are numerous people who disagree with you about the vapor, which would make even perfection not good enough. There are locking compounds designed specifically for use on and around plastics, there is no reason to use a product which the manufacturer specifically warns isn't compatible with them.
RE: PSA -- Tool change issues over time -- docks easily loosen
Rather than just say Loctite 243 (red or even blue) will damage plastics (which it can make brittle) and claim other things won't. Let the forum know the other options that do work.
Some are:
ProTek RC Blue Thread Lock
Team Associated Blue ThreadLock
Both made for RC,drones etc.. Designed for plastics and metal with great resistance to vibrations (Used on Nitro powered RC cars etc..)
I am not trying to upset anyone, just quell the dispute a bit with options that would work :))
I am not affiliated with any of the above.
RE: PSA -- Tool change issues over time -- docks easily loosen
There are people who argue everything, including that the earth is flat, so it's pointless as usual to have any debate on a forum. A bunch of anecdotal evidence from people with no actual experience.
Those warnings you read about are for using it on plastic threads, not metal.
Anyways enjoy and carry on.
RE:
Rather than just say Loctite 243 (red or even blue) will damage plastics (which it can make brittle) and claim other things won't. Let the forum know the other options that do work.
Loctite 425 is also apparently a safe option, but I'm not going to recommend anything without testing it, and people need to be warned of bad advice that could result in damage to their very expensive Prusa XLs. If you plan to use anything like this, I'll suggest testing it on some printed PETG parts first.
Or you could just check them periodically to make sure they haven't come loose. You can do a visual inspection of dock alignment by just looking at them from one side, check for looseness by feel, and take a few minutes to check the actual screws if you're concerned. Honestly, I doubt locking the threads is even useful, it seems more likely that you'll need to adjust things due to the plastic creeping under the attachment forces.
RE: PSA -- Tool change issues over time -- docks easily loosen
Umm, there are no plastic parts that would affect the dock alingment.
The dock is made from metal that is screwed directly to the metal frame extrusion, plastic is used only in the cable/PTFE tube holder part, which is screwed to the dock with different screws.
RE: PSA -- Tool change issues over time -- docks easily loosen
The issue people mentioned with plastic parts was never where it screws in only near by. Some people were just being cautious and my comment was address that issue as well as the possible losseng