Oh look another stripped grub screw post
Got my Mk3 in the mail today. Assembly has been going fine if not a bit tedious. But like a bunch of people before me, when going to align the extruder I've found the stupid grub screw is stripped. So now instead of finishing my printer like I'd hoped I'm going to have to wait for stores to reopen so I can go by a dremel cutting disc or some other implement to remove this cheese-grade screw.
Seriously, if theres already a bunch of threads about this issue its time to either switch to a different extruder or tell whoever makes it to get their crap together. This is hardly acceptable for a product that costs this much.
Re: Oh look another stripped grub screw post
A big screw requires a lot of power, a small screw a small force.
Bear MK3 with Bondtech extruder
Re: Oh look another stripped grub screw post
Torque - your best friend and worst enemy. That's why mother nature made torque wrenches. Fine precision equipment usually requires a little finesse. And even though stainless is tough, it is one of the weaker steels used for fasteners. Thus, use less force with stainless.
And, if a set screw is used in aluminum, that finesse requirement gets doubled because aluminum is even softer than stainless.
Re: Oh look another stripped grub screw post
10 inch pounds is about right for this bondtech grub screw (or about 0.8 newtons) with the supplied allan wrench use the short arm to apply the tightening have the long arm in the grub screw and just use finger pressure to tighten on the short arm. I use blue locktite on all metal to metal fasteners on the printer.
Re: Oh look another stripped grub screw post
I use blue locktite on all metal to metal fasteners on the printer.
This is key. I almost wish Prusa would include a small tube with the kit when it is shipped.
Re: Oh look another stripped grub screw post
I use blue locktite on all metal to metal fasteners on the printer.
Technically, a shaft part locked with a set screw on a detent and another set screw 90 degrees away is pretty much like a double nut on a bolt. You shouldn't need Loctite.
Someone else posted that the most common reason for the set screws stripping is the user isn't inserting the Hex key into the screw far enough, so all the torque gets applied to the thinnest part of the screw, and crunch it goes.
Re: Oh look another stripped grub screw post
I managed to mangle the heads of both extruder set screws that came with the kit. I ordered some of BondTech's own m3x2 set screws ( https://www.bondtech.se/en/product/setscrews/ ) and the seem to be much easier to work with. No problems torquing them down. And now I have many spares.
In the US, they can be ordered from here: https://www.partsbuilt.com/bondtech/set-screws-for-bondtech-extruders/
Re: Oh look another stripped grub screw post
I use blue locktite on all metal to metal fasteners on the printer.
This is key. I almost wish Prusa would include a small tube with the kit when it is shipped.
nothing but grub screw issues since i got the printer, read one time dont use it, and regretting every bit if that "opinion" of not using loctite, now i have an mk3s to assemble where the last few layers are...iffy. stopping by store for some tonight. this need to be in the build manual. period. its a step they use in house isnt it.
but wait, it states it in the mk3s upgrade manual this time.
"Don't use any glue to fix the screw in place, you won't be able to release it, in such case you might have to replace the entire motor."
oh come on?!?
and we’ll be saying a big hello to all intelligent life forms everywhere … and to everyone else out there, the secret is to bang the rocks together, guys.
Re: Oh look another stripped grub screw post
I use blue locktite on all metal to metal fasteners on the printer.
This is key. I almost wish Prusa would include a small tube with the kit when it is shipped.
nothing but grub screw issues since i got the printer, read one time dont use it, and regretting every bit if that "opinion" of not using loctite, now i have an mk3s to assemble where the last few layers are...iffy. stopping by store for some tonight. this need to be in the build manual. period. its a step they use in house isnt it.
but wait, it states it in the mk3s upgrade manual this time.
"Don't use any glue to fix the screw in place, you won't be able to release it, in such case you might have to replace the entire motor."
oh come on?!?
lucky for us locktite isn't a glue
I have a Prusa,therefore I research.
Re: Oh look another stripped grub screw post
lucky for us locktite isn't a glue
Pretty sure it's a cyanoacrylate, just like superglue. Maybe not a permanent one, but a rose by any other name...
Re: Oh look another stripped grub screw post
lucky for us locktite isn't a glue
Pretty sure it's a cyanoacrylate, just like superglue. Maybe not a permanent one, but a rose by any other name...
maybe loktite's superglue. I'm talking loktite 221/222/242
I have yet to "loctite" my fingers, now superglued fingers.. countless
I have a Prusa,therefore I research.
Re: Oh look another stripped grub screw post
lucky for us locktite isn't a glue
Pretty sure it's a cyanoacrylate, just like superglue. Maybe not a permanent one, but a rose by any other name...
There are many different types for different applications. Green is generally permanent and penetrates down threads.
In this instance I'd go for a blue if you are using loctite branded product.
Typical colours
Low strength- Purple
Medium strength- Blue
High strength or temperature- Red
Penetrating- Green
Edit, heres the manufacturers instructions, blue would still be my preference.
http://henkeladhesivesna.com/blog/the-difference-between-red-blue-green-and-purple-threadlockers/
Re: Oh look another stripped grub screw post
to top it off, bondtech recommends some loctite on the gear, so, i will go with the core of that recommendation, B242 on my shopping list.
page 8 : https://www.bondtech.se/wp-content/uploads/2019/01/Assembly-manual-Bondtech_Prusa_i3_V1.01.pdf
and we’ll be saying a big hello to all intelligent life forms everywhere … and to everyone else out there, the secret is to bang the rocks together, guys.
Re: Oh look another stripped grub screw post
to top it off, bondtech recommends some loctite on the gear, so, i will go with the core of that recommendation, B242 on my shopping list.
page 8 : https://www.bondtech.se/wp-content/uploads/2019/01/Assembly-manual-Bondtech_Prusa_i3_V1.01.pdf
"Insert a push fit clip between the HotEnd and the collet." at least bondtech knows what's up.
as for Loctite kinda common practice for set screws.
I have a Prusa,therefore I research.
Re: Oh look another stripped grub screw post
As an option for those without Loctite or similar thread glues, in the old school, a quick dab of fingernail polish or enamel paint will also hold the screw and be easy to remove should the need arise. But the best way to keep a set screw in place is the proper torque.