Hi all,
the two screws that hold the P1s/X1c hotend must be used only once? Or can I always use the same two by switching from a 0.2mm nozzle to a 0.4mm one?
Thanks
Screws, by definition in mechanical design, are multi-use fasteners, so yes, you can use them again.
However, if the screw you’re removing has blue at the end, you’re seeing thread adhesive, which is generally used to secure a screw in place and prevent it from backing out due to vibration or thermal expansion and contraction. Some manufacturers suggest reapplying thread adhesive, but in my experience, it’s unnecessary in this use case. The adhesive—if used—is typically applied so liberally at the factory, that enough remains for repeated removals and insertions.
Still, if you want to use another screw that doesn’t already have adhesive, you can apply it yourself. It’s readily available at any hardware store that sells nuts and bolts. Use the blue kind; the red kind is for high-heat applications like engine bolts and is semi-permanent, requiring a torch to remove.
Unfortunately, Loctite—the main maker and inventor of thread adhesive—adds confusion by putting the blue adhesive in a red bottle. As if we needed that.
Heres’ what I mean. M243 is the blue and is intended for removable use.
But it also comes in a medium-hold red bottle too as 222 even though the actual glue is blue/purple, so be mindful.
Personally I keep a bottle of 242 on hand in my shop because it’s generic enough to work in almost all cases.
Here’s a handy table of Loctite products but there are now plenty of competitors in the “Thread Adhesive” category, it’s just that Loctite was the first in that category but don’t get hung up on brand names. Buy on price.
| Loctite Product | Color | Strength | Typical Uses | Removability | Temp Resistance (°F) | Cure Time |
|---|---|---|---|---|---|---|
| 222 | Purple | Low | Small screws, soft metals | Easy with hand tools | up to 300°F | 10 min (fixture) |
| 242 | Blue | Medium | General-purpose, removable bolts | Hand tools | up to 300°F | 10 min (fixture) |
| 243 | Blue | Medium | Oil-tolerant version of 242 | Hand tools | up to 360°F | 10 min (fixture) |
| 248 | Blue | Medium | Stick version of 242 | Hand tools | up to 300°F | 10 min (fixture) |
| 271 | Red | High | Permanent, heavy-duty bolts | Requires heat & tools | up to 300°F | 10 min (fixture) |
| 272 | Red | High | High-temp version of 271 | Requires heat & tools | up to 450°F | 60 min (fixture) |
| 277 | Red | Very High | Large bolts and studs | Heat + tools required | up to 300°F | 60 min (fixture) |
| 290 | Green | Medium-High | Wicking grade for preassembled | Heat + tools recommended | up to 300°F | 20 min (fixture) |
BTW: One item I strongly recommend that everyone have in their kit is the Bambulab spare scew kit. For $15, it’s worth it. And this coming from a person who has a well equipped shop with various metric screws on hand. However, Bambu makes generous use of hard to find and one-off custom shoulder screws and springs that cannot be easily found on the Internet.
3 Likes
Didn’t even know that kit existed. Definitely would be worth having since I’m prone to lose screws while working on stuff 
First of all, thank you for the quick, precise and detailed answer…
Given my laziness and taking note of the convenience/usefulness of having the kit of assorted screws from bambulab, I just ordered it…
Thanks