Anet A8 Printer and Loctite - Page 1
Forum section: electronics / general

author: bostonman
author_rank: Super Contributor
timestamp: January 19, 2021, 12:20:51 am
content: I have a question.In order to make my Anet A8 printer more mechanically stable, I used Loctite on the screws/nuts to prevent them from loosening. Sometime ago I overtightened some and the pieces cracked, so this time I was extra careful and only made the screws relatively snug.Today (after one day) I looked and basically every single piece around the nuts is cracked. It doesn't look like the pieces chemically disintegrated, but, the pieces that cracked and broke off also had many tiny pieces falling off too. It was so bad, it looks like I used a breaker bar to tighten the screws.Is the material for the printer 100% acrylic and does Loctite eat away at this material?

author: Whales
author_rank: Super Contributor
timestamp: January 19, 2021, 12:29:38 am
content: I've had a loctite product do something similar to the plastic threads inside a laptop lid. The plastic didn't "look" chemically damaged, but it became very fragile and broke into many tiny pieces.What model of Loctite? They probably list plastic compatibility in their datasheets/product info.

author: thm_w
author_rank: Super Contributor
timestamp: January 19, 2021, 12:40:45 am
content: From here it sounds like you should not use normal loctite:https://www.rctech.net/forum/electric-off-road/500972-loctite-ok-screw-screws-into-plastic.htmlAlthough the loctite shouldn't actually come in direct contact with the acrylic unless you really poured it on.

author: bostonman
author_rank: Super Contributor
timestamp: January 19, 2021, 12:46:54 am
content: I should have included that:It's Loctite 222 (red) part number: 21464I planned to look on their website and/or contact them, but wanted to start off by confirming it's 100% acrylic.

author: bostonman
author_rank: Super Contributor
timestamp: January 19, 2021, 02:54:56 pm
content: I stated the stuff I have is 'red' but apparently this is the color for the high strength stuff.Looking at the 'threadlocker' label on the bottle, it looks red (or pink), but it's labeled 'low strength'. Hopefully I didn't confuse anyone.

author: mikerj
author_rank: Super Contributor
timestamp: January 19, 2021, 03:24:32 pm
content: Loctite can absolutely cause cracking of plastics. The datasheet for Loctite 222 states "This product is not normally recommended for use on plastics (particularly thermoplastic materials where stress cracking of the plastic could result)."Acrylic is a thermoplastic...

author: bostonman
author_rank: Super Contributor
timestamp: January 19, 2021, 03:35:21 pm
content: Is acrylic the material used for the printer frame? From my research, it is, but wasn't sure if it's a percentage of acrylic.A few weeks ago i tested the acrylic by pouring some on the flat surface and letting it sit a day or two. As expected, it didn't dry (my understanding: it dries in the absence of air), it didn't crack the acrylic, but it also didn't go through its normal curing process.The big question to help me understand is what happens in the case of it curing around screws/nuts to cause the cracking? Does it become hot, expand, etc....?

author: thm_w
author_rank: Super Contributor
timestamp: January 19, 2021, 10:31:26 pm
content: Manufacturer says its acrylic, I would believe them. Its going to have some dye in it to make it black but I would expect that is about it.Its possible most of the cracking is just from stress. Since they cut the edges with the laser perfectly square that contributes to stress concentration:https://www.ponoko.com/blog/how-to-make/how-to-make-snug-joints-in-acrylic/

author: bostonman
author_rank: Super Contributor
timestamp: January 20, 2021, 02:28:58 am
content: It's possible they cracked from stress, but I didn't seem to over tighten them.All I did was turn the screw until it was snug and then stopped.Years ago I remember reading something about Threadlocker causing less friction and throwing off a torque wrench. Maybe the Threadlocker caused the screw to feel loose when in actuality I was over tightening.Besides the fact I may be unable to find replacement parts, I'm hoping to figure out what I did wrong before I (hopefully) get new ones. Today I took two broken pieces (although basically everything is broken at this point) and tightened the screw to what felt like the same torque, but only I didn't use Threadlocker. If tomorrow it's not cracked, I may add Threadlocker and see if it cracks.Upon getting this printer, I didn't realize the parts were acrylic and tightened the screws quite tight without anything cracking. After I decided to spend the extra time and use Threadlocker, that's when the pieces cracked. Thinking it was from over tightening, I bought new pieces, used Threadlocker, and didn't tighten them as tight (as I mentioned above).But as a few pointed out, the Threadlocker isn't safe for acrylic (or plastics). So maybe it really wasn't from over tightening - or so I hope.

author: bostonman
author_rank: Super Contributor
timestamp: January 21, 2021, 04:33:54 am
content: I got the following directly from the company:This product is an anaerobic and they will attack many plastics including acrylic. If you want a removable grade product, Loctite 425 is a better solution and this is compatible with both metals and most plastics including acrylic.Has anyone reading this thread assembled the Anet A8? I've attached a picture of what happened around the nuts and screws. Looking at it, the cracks looks stress related, but I was careful when tightening the screws. Basically once the screw stopped turning with gently turning the screwdriver, I went slightly more and stopped. I'm uncertain how the Threadlock could have done this because I'd imagine the chemical would eat the acrylic instead of cracking it in a way that looks stress related.Anyway, if anyone has assembled this printer, I'd appreciate feedback on how tight to make them. I haven't found replacement pieces, so I'd appreciate any input on finding replacement acrylic pieces too.Any help locating a full set of acrylic would be appreciated.Thanks

author: mikerj
author_rank: Super Contributor
timestamp: January 21, 2021, 12:51:46 pm
content: In this case the stress cracking has nothing to do with how tight the screws were done up, the Loctite embrittles the plastic and introduces stress in the material which causes the cracking. Loctite know all about this which is why they explicitly say not to use anaerobic curing threadlockers on thermoplastics.

author: bostonman
author_rank: Super Contributor
timestamp: January 21, 2021, 03:17:05 pm
content: QuoteThis gives me a little satisfaction knowing it wasn't overtightening because I was quite gentle.If the Loctite would make the surrounding area brittle, how come the acrylic wouldn't just break off where the stress is (around the nut)? The way I'm visualizing it: the Loctite makes the acrylic brittle, the two little pieces that hold the nut in place break off, and the screw/nut is left dangling. This almost looks like the Loctite caused screw contraction.Anyway, I appreciate the input from everyone as this was bothering me. Now I need to locate replacement pieces.

author: wraper
author_rank: Unknown
timestamp: January 21, 2021, 03:30:51 pm
content: Quote from: mikerj on January 21, 2021, 12:51:46 pmIt will not harden when used on thermoplastics. Extruded acrylic is prone to cracking in the slightest presence of mechanical stress FWIW.

author: bostonman
author_rank: Super Contributor
timestamp: January 24, 2021, 03:24:28 pm
content: I'm uncertain if I should ask this question by continuing this thread or start a new one, but I'll start by asking here.Has anyone assembled this printer? As you can see from the picture, the nut is in a spot that places lots of stress on the acrylic.If I leave the screws loose, then the frame isn't sturdy, if I tighten them, I'm afraid of cracking. So I'm uncertain how snug to make these screws and wondering if anyone has assembled this and can provide feedback.The pieces fit into each other and it looks like the screws are just to hold the pieces together, not to add strength, but leaving them loose doesn't seem to make much sense as they'll just fall out over time.

author: wraper
author_rank: Unknown
timestamp: January 24, 2021, 03:58:31 pm
content: Maybe use a little bit of adhesive like RTV silicone between surfaces for strength and tighten the screws just a little bit.

author: bostonman
author_rank: Super Contributor
timestamp: January 24, 2021, 04:03:15 pm
content: I considered, but I think it would cause a lack of flexing ability and crack the frame.It's not a durable frame.

author: wraper
author_rank: Unknown
timestamp: January 24, 2021, 04:55:35 pm
content: It will not cause concentrated stress on small points like Screws. Not to say silicone is elastic.

author: mikerj
author_rank: Super Contributor
timestamp: January 25, 2021, 04:59:06 pm
content: Quote from: wraper on January 21, 2021, 03:30:51 pmNot sure how this is relevant. Yes acrylic is quite a brittle material, but that doesn't mean that it cannot be fastened with screws provided care if taken. When screws are overtightened acrylic tends to crack right then, not days later. OTOH the material changes introduced by anaerobic threadlockers causes cracking some time after the screws have been tightened.This is not a new problem, a quick search even showsother peoplediscovering why anaerobic thread lock should not be used on this printer frame.

author: wraper
author_rank: Unknown
timestamp: January 25, 2021, 05:03:33 pm
content: Quote from: mikerj on January 25, 2021, 04:59:06 pmSimply not true.QuoteIt can be tightened if the thing is designed that force is evenly applied around the hole without any bending at any point. Also there is a big difference between extruded and cast acrylic. Cast acrylic is an order of magnitude harder to crack and cracks tend to remains small, not extend over material length. The downside it's more expensive and thickness is not stable.

author: bostonman
author_rank: Super Contributor
timestamp: January 26, 2021, 12:26:38 am
content: QuoteI came across that the other day.As for tightening the screws, I posted a picture of the nut and screw area. YouTube has an assembly video where the guy used a drill to tighten the screws. I contacted him and he claims his frame hasn't cracked, and suggested I make the screws snug, but not too tight.I'm shocked the vibration and shock of the drill didn't cause cracking.

author: Ranayna
author_rank: Super Contributor
timestamp: January 26, 2021, 02:39:08 pm
content: With my A8 i had a bit of trouble at the beginning, because the nuts are too small for the slots, and turned when tightening the screw.What i did was to slide a small flatblade screwdriver, no wider than the nut is tall, into the hole, pressed sideways against the nut. With that flatblade in place i tightened the screws by hand. So not really all that tight.Sometimes, where i was able to pinch the slot for the nut with my fingers, i just did that. My skin squeezed into the slot on both sides was enough to keep the nut from spinning. After a bit of initial tightening, i was generally able to let go and tighen a bit more. But generally i was very careful to not overtighten, I stopped when i was not able to turn the screw with my finger.The printer is now about 2 years old, but rarely used. I neither saw any cracking, nor did i have to retighten the screws. But it is mounted to a sturdy baseplate, so the printer does not get any undue stresses when moved around.

author: bostonman
author_rank: Super Contributor
timestamp: January 26, 2021, 03:12:34 pm
content: QuoteSo you didn't use a screwdriver?A guy who posts Anet A8 videos (Daniel - he has an accent) stated some screws have the problem you're describing. I'm assuming they are cheap parts and not threaded well. He suggested just tossing whichever screws/nuts have that problem and using the spares and/or buying new ones. I may test them before inserting them to check for proper turning.In all videos, everyone uses a screwdriver, however, it's hard to determine has much force is being used. The one guy who used an electric drill shocked me. I've exchanged a few messages with him, and, to my surprise, he's stated nothing has cracked.Looking at the nut area, any amount of force causes a high lbs/inch because those nuts are tiny. Personally, when I saw how brittle the acrylic was after using Loctite, I lost all confidence in attempting to tighten the hardware.Unfortunately I haven't found a video or anything online that describes just how tight to make the screws. Your approach is safe for sure, but I imagine with more use, those would be coming out and the printer would wobble causing poorly printed parts.

author: Monkeh
author_rank: Super Contributor
timestamp: January 26, 2021, 03:35:36 pm
content: The whole frame wobbles and causes poor prints even if the screws are tight..

author: bostonman
author_rank: Super Contributor
timestamp: January 26, 2021, 03:40:53 pm
content: A few upgrades help that. The front and rear bracket along with the Hulk (although I haven't installed the Hulk yet, but I have it printed).The initial prints I did came out quite well. Sadly, I tried to improve too much with overtightening and then thought Loctite would be nice upgrade.Boy, was I wrong.

author: Monkeh
author_rank: Super Contributor
timestamp: January 26, 2021, 03:55:38 pm
content: This is now what, frame #3 with piles of upgrades bolted onto it?

author: bostonman
author_rank: Super Contributor
timestamp: January 26, 2021, 04:00:17 pm
content: This was my discussion upon getting this printer that you spend more time printing upgrades than using it.I could just toss the printer and get a better one, but for a few reasons, I'd prefer keeping this. Had I not messed with the frame, and left it as is, the printer would still be in great shape.

author: evac
author_rank: Contributor
timestamp: January 26, 2021, 04:53:49 pm
content: Why not just switch to an aluminum frame?Something like:https://www.thingiverse.com/thing:2263216All the hardware can be easily sourced and it's relatively cheap.In my case, I think total cost was around €50, all from eBay.You can find EU sellers where you can purchase cut-to-size pieces of aluminum extrusion, and all the other hardware is easy to find.I would highly recommend it as it is a world of difference from the crappy original frame.Edit: I didn't see properly and mistook your flag for UK, so never mind about the EU sellers, but I would guess it would easy to find also in US.

author: Ranayna
author_rank: Super Contributor
timestamp: January 26, 2021, 05:08:10 pm
content: Yes, i used a screwdriver.It's also not an issue with the threading of the screws, if so, then only with the start of the threading.The nuts in my kit were just too small and turned with the screw, so i had stop them spinning. Sometimes my fingers were enough, sometimes i needed that small screwdriver. Once i got the nut engaged, once there was enough friction on the nut i could let go. I then tightened a bit more, but only enough that when i put my finger on the screwhead i felt no movement, and turning my finger on the screhead did not loosen the screw again. I would *never* have imagined that the acrylic is sturdy enough to use a power tool.There are replacement frames on ebay. You can get an acrylic one like the one you have for less than 20 bucks, i was not able to find a metal frame for less than 70, but did not look all that long.

author: bostonman
author_rank: Super Contributor
timestamp: January 27, 2021, 02:27:19 am
content: I have seen the metal frame kit. Also, unfortunately the acrylic being sold is only a few pieces and doesn't include all the ones I need.The metal frame looks quite good, however, I see two problems: the first is the pieces to hold things together are 3D printed which implies they are weak points in the frame. Also, most of the prints I've printed with the printer have been more than suitable for my needs. Spending more money on trying to improve the design seems a waste and ideally it would make sense to buy a much better quality printer (>$2000) should I have the need to print more accurate parts.It's too bad the directions don't give better assembly instructions on their intentions of how tight to make the screws. Looking at how the pieces lock together, it seems the screws just need to be turned until they catch. If this is the case, I image extensive use would cause them to loosen. On the other hand, if I use safe (and I emphasize this word) Loctite (safe for plastic) on the screws, I need to assemble, align, remove the screws, and apply the Loctite. Using the Loctite as the frame is being assembled will cause issues trying to loosen them once the frame needs to be aligned with the threaded rod.

author: Ranayna
author_rank: Super Contributor
timestamp: January 27, 2021, 07:45:14 am
content: Do you already have mounted your printer on a base board?I think that has contributed a lot to the life of mine, since i can move it around without any flexing at all. And i am doing that regularly, since i do not have much bench space.In the beginning before i had the base board, every time i picked it up it went horribly out of alignment and needed a lot of readjusting.

author: bostonman
author_rank: Super Contributor
timestamp: January 27, 2021, 02:01:43 pm
content: Yes, it's mounted to a thick sheet of plexiglass that was enough, but I improved it by framing the bottom with 2x3s.Also, I printed the brackets to hold down the threaded rod along with the front and rear bracket brace. I've also printed the Hulk support, but hadn't installed them yet.

author: bostonman
author_rank: Super Contributor
timestamp: January 31, 2021, 03:58:28 pm
content: Just a quick update.I screwed two pieces together without using Loctite; these were sections of a broken piece that weren't subjected to Loctite prior; basically pieces I plan to throw away.First I tightened the screw to where it caught. Basically this was loose enough that it would probably unscrew with the slightest vibration.Next I tightened the screw with approximately the same amount of torque used when I applied Loctite the first time.After I went quite tight, and finally tighter than I would normally go to really stress the acrylic. In all cases I waited at least one day between tightening the screw more, and, although I haven't checked it today, as of yesterday, I didn't see any cracking. Also, I tried stressing the piece a bit by gently bending it and this also didn't cause any cracking.These tests was to check how tight to safely make the screws, and whether the acrylic is really brittle. It seems the Loctite does quite a bit of harm to the acrylic because before when using the Loctite, I hadn't tightened the screws tight, and I applied just a bit of pressure on the frame. The piece literally crumbled into tiny grains with the slightest force on the frame.Without using Loctite, I can tighten the screws tighter than before, apply bending force, and the acrylic holds up.

author: bostonman
author_rank: Super Contributor
timestamp: February 04, 2021, 02:36:58 pm
content: After many days, I tried making the screw tighter, and, after about three-days, the acrylic still looks good.At the moment, the screw is beyond a safe torque and the acrylic is still holding up. Thankfully this has given me more confidence in assembling the new pieces. Once I begin assembly, I plan to put much less torque than what is on the test pieces, so I should be safe; providing I don't use Loctite.

author: bostonman
author_rank: Super Contributor
timestamp: February 12, 2021, 02:28:35 am
content: Quick question about a base.I've seen others have mounted their printer to a base. I went to Home Depot and Lowes to look for wood, however, everything was warped just shy of being a pretzel.Does anyone who has mounted this have any advice on where to buy a nice flat surface piece of wood?