Locktite the Screws?  

Re: Locktite the Screws?

I don't foresee a reason why it would be a bad idea to use blue Loctite to help keep the frame screws from vibrating loose. I was planning on using it on my build so I'll pay attention here to see if someone has a logical reason why it shouldn't be used.

Re: Locktite the Screws?

A couple of screws have fallen out of my two machines in around six months. It's not poor assembly either, the same screw on the front of the heat bed has fallen out of one of the printers a couple of times now. It's just inherent in bolting together something that vibrates quite a bit.

I've bought myself some blue (weak) Loctite ready for when my MK3 kits arrive in the New Year and I spend a couple of weekends striping them and rebuilding.

Re: Locktite the Screws?

I too plan using Loctite Blue on my MK3 when it arrives. Later, if I have to remove a Loctited screw I could put a hot soldering iron on the bolt head or nut for a few seconds and that should allow me to remove the fastener.

Re: Locktite the Screws?

I used blue loctite stick on most of the metal to metal connections, such as frame, steppers, bed, and some of the extruder parts. Also used it on the Y-axis idler, as the bolt didn't seem to completely engage the nyloc insert before it began deformity the part.

Felt like cheap insurance to avoid trouble down the road.

Re: Locktite the Screws?

Be careful. Loctite is known to degrade most plastics. I'm not sure what it's effect on PETG is.

Re: Locktite the Screws?

"Be careful. Loctite is known to degrade most plastics. I'm not sure what it's effect on PETG is."
I only use it on metal screws or bolts and their associated nuts or threaded metal parts I do not use it on plastic..

Re: Locktite the Screws?

As long as you just use it where it belongs, i bet you won´t get in trouble with the plastic parts.
And if you use loctite blue, theres is (normaly) no need to heat the screw to become loose again.
The blue type is just there to eleminate vibrations between e.g. the screw and thes crew nut.
And of course to glue it together, but just ab bit.

Re: Locktite the Screws?

I too plan using Loctite Blue on my MK3 when it arrives. Later, if I have to remove a Loctited screw I could put a hot soldering iron on the bolt head or nut for a few seconds and that should allow me to remove the fastener.

You shouldn't need heat to remove blue loctite. It will be a little harder to unscrew, but not enough to be worth mentioning. It's the red loctite that requires heat to unscrew.

Just be careful. Some manufacturers sell red threadlocker in a blue bottle and blue threadlocker in a red bottle. I'm convinced they do this to confuse you and buy another one. Just be sure the actual liquid is blue.

Loctite makes a better product for small screws like this. Blue threadlocker is really intended for larger screws.

Purple loctite:
https://www.amazon.com/Loctite-38653-Purple-Strength-6-milliliter/dp/B0002KKTT0/

Re: Locktite the Screws?

You need to make sure you do not get a high temp threadlock which is blue also. It only softens around 140C and above, below that you would break the parts trying to get them apart. I have ripped aluminum nozzles in half before trying. 😳

Re: Locktite the Screws?

I too plan using Loctite Blue on my MK3 when it arrives. Later, if I have to remove a Loctited screw I could put a hot soldering iron on the bolt head or nut for a few seconds and that should allow me to remove the fastener.

You shouldn't need heat to remove blue loctite. It will be a little harder to unscrew, but not enough to be worth mentioning. It's the red loctite that requires heat to unscrew.

Just be careful. Some manufacturers sell red threadlocker in a blue bottle and blue threadlocker in a red bottle. I'm convinced they do this to confuse you and buy another one. Just be sure the actual liquid is blue.

Loctite makes a better product for small screws like this. Blue threadlocker is really intended for larger screws.

Purple loctite:
https://www.amazon.com/Loctite-38653-Purple-Strength-6-milliliter/dp/B0002KKTT0/

Isn't that one of the silliest things about locktight products!

Does anyone know of other brands that are equivalent to locktight?

I like the "glue stick" packaging, works perfect to dip a screw in and not have it drip out or get squeezed. Those sticks sure are expensive for such a small item despite the lifespan. Would really rather find a inexpensive equivalent product if there is one avalible?

Re: Locktite the Screws?

I just lost a Print because the 2 screws spring tensioning the idler gear against the extruder gear got loose and it stoped driving the filament.
Filament sensor caught it and paused the print. Sadly is was to stupid to realise what happened and stopped the print because i thought it jammed up.

Well i endet up modifying the idler part and change it from the normal nuts to nylon lock nuts. Print it out and done. so no more loosening from those. not sure if i screwed up something during assembly and tightening of the srews or if they just rattled loose.

Edit: This is the changed Idler:
https://grabcad.com/library/prusa-mk3-idler-with-nyloc-nuts-1

Re: Locktite the Screws?

I just lost a Print because the 2 screws spring tensioning the idler gear against the extruder gear got loose and it stoped driving the filament.
Filament sensor caught it and paused the print. Sadly is was to stupid to realise what happened and stopped the print because i thought it jammed up.

Well i endet up modifying the idler part and change it from the normal nuts to nylon lock nuts. Print it out and done. so no more loosening from those. not sure if i screwed up something during assembly and tightening of the srews or if they just rattled loose.

I had to go back and check that was not how they did not use nylock nuts! They used captured square nuts...

I suspect that is the correct way to make those parts!

I recall my screws not giving any resistance against the Spring pressure, so while the threads are formed well, they sure don't assist the assembly in this part from wandering and undesirably changing tension.

You should share that file, seems like a easy clearly obvious improvement!

Re: Locktite the Screws?

Edit: This is the changed Idler:
https://grabcad.com/library/prusa-mk3-idler-with-nyloc-nuts-1

Could you please put it somewhere not requiring a sign up?

Re: Locktite the Screws?

Edit: This is the changed Idler:
https://grabcad.com/library/prusa-mk3-idler-with-nyloc-nuts-1

Could you please put it somewhere not requiring a sign up?

I put it up on Thingiverse but it takes 24H for new users util it gets published.
https://www.thingiverse.com/thing:2717948
https://grabcad.com/library/prusa-mk3-idler-with-nyloc-nuts-1

If you need it sooner. Pm me.
I printed it with 5,5mm space for the nuts but it was little bit too tight. But i made it work without reprinting. Still changed the design to 5,6mm bevor upload. Should be smoother now.

Cheers

Re: Locktite the Screws?

Excellent Mod!

I made the same mod in Fusion 360. Here is the file (a .zip file with both the .step and .stl file). Let me know if you want me to make any changes.
http://www.pervinco.com/Prusa_MK3/extruder-idler-hexnuts.zip

Re: Locktite the Screws?

I used blue thread locker on my MK2S kit with no issues for over a year now - no loose screws, no degraded ABS. I used the same in my MK3 kit. We'll see how it affects PETG. So far, no issues.