Forum adverts like this one are shown to any user who is not logged in. Join us by filling out a tiny 3 field form and you will get your own, free, dakka user account which gives a good range of benefits to you: No adverts like this in the forums anymore. Times and dates in your local timezone. Full tracking of what you have read so you can skip to your first unread post, easily see what has changed since you last logged in, and easily see what is new at a glance. Email notifications for threads you want to watch closely. Being a part of the oldest wargaming community on the net. If you are already a member then feel free to login now.

This seems to be a common problem but I've not found a clear solution yet online and would be grateful for any advice.

I have an Elegoo Saturn with Water-Washable resin. The printer was 2nd-hand and had been heavily-used.
FEP is new.
LCD screen (4K) is old and worn with some loss of definition coming through into the prints.
The build-plate is gouged and battered, so I thought it would be a good idea to attach a magnetic/replaceable one from KOYOFEI: https://www.amazon.co.uk/gp/product/B091M86DGX/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

I bought it a year ago and didn't get round to attaching it until now
The printer already had a 2mm spacer. I increased this to 5mm
I read that the adhesive needs time to cure and gave it about 3 days zeroed up against the LCD screen

The test rook printed ok. A full plate of minis printed ok
And then the magnetic part starting coming unstuck from the build plate and drooped down. The thin steel sheet was already removed with the test miniatures, the problem's with the adhesion of the magnet to the original Elegoo build plate
Apparently the water-washable resin might have dissolved the 3M adhesive (if indeed the adhesive was genuine) - this seems like a dumb design flaw in a product designed to rectify a dumb design flaw

My question is should I re-attach with another adhesive - and if so what? Or since the original build plate is old anyway might it be better to cut some screw holes into it?
Or are these magnetic plates rubbish and should I revert to buying a replacement build plate from Elegoo?

Hm.... I had a magnetic plate on a Mars 2 Pro and was using water washable resin at the time, but I can't say that I had any problems with the glue. It being smaller I'm pretty sure the pressure was less, though.

In the end it didn't really work for me (I had to burn the initial layers longer and the prints only poppe right out on the biggest ones, so I ended up having to do just about the same) so I haven't really bothered from then on.

In my experience, if you dial in right the first layers, they pop off the plate easy enough.

 cattyandco wrote:

And then the magnetic part starting coming unstuck from the build plate and drooped down.

Hmm, that's interesting. I also experienced issues using a magnetic build plate on my Saturn 2, but it was the magnetic plate pulling away from the magnetic strip. It sounds like the cause might be the same though - I had a small chip/gouge in one edge of my magnetic strip that was allowing resin to seep in between the metal plate and the magnetic strip. Once it gets in there it tends to continue to infiltrate and cause the plate to slowly peel away, especially when printing stuff with large cross sections that produces a lot of suction/pull. I fixed the issue by carefully filling the gouge with a little pollyfilla intended for bathrooms and kitchens.

You mentioned your build plate was gouged and battered. If any of those gouges reach the edges of the plate/magnetic strip I imagine they could cause the same problem, but between the magnetic strip and build plate. Lots of gouges might also reduce the adhesion of the magnetic strip generally, but my money is on the resin infiltration being the main cause.

Sadly if my diagnosis is correct your best fix is probably to buy a new build plate, whether or not you want to continue using a magnetic plate with it.

I've found the magnetic plate handy when something is well and truly stuck on there because I can just remove and flex it, but generally I avoid taking it off whenever possible because it is necessarily to completely clean and dry both the magnetic strip and metal plate before re-attaching it. I've always found it a lot easier to remove stuff from the magnetic plate than I did directly from the build plate though, not sure why.

I love the magnetic plates. Build plates tend to be a weird shape. Having a super flat thing you can take off and lie totally flat on the work surface I find to be invaluable. Also it massively reduces the chance of you accidentally messing up your build plate orientation by accident when removing prints.

I have 2 of the things that I cycle, so that I can get a new plate printing while I process the one that has just finished.

The magnetic bit has just started to come away from my build plate as well, so I bought another one. compared to all the other consumables in this hobby, spending £10 every couple of years to freshen the build plat up seems reasonable

Mine (on a 6" printer, but same principle of course) got unstuck from a nigh-new when applied to build plate after less than six months. Personally I've just not replaced it, but either way it does seem to be a consumable.

Thanks all for your comments. I removed the magnetic sheet: the (3M?) adhesive had dissolved where it was in contact with the (water-washable) resin - but once it dried it returned to being sticky.

I replaced this with Gorilla Glue's 2-part clear epoxy - which is similar to Araldite.

A test print had issues with some models warping. So I'm going to re-try it when the weather is better.

What I don't want it to be is that the adhesive between the build-plate and the magnetic sheet didn't dry flat enough.

Also bad would be if some resin between the magnetic sheet and the steel flexible sheet was enough to worsen the grip, and allowed the steel sheet to flex as it pulled away from the FEP.

But hopefully it was a 1-off.

 cattyandco wrote:

Also bad would be if some resin between the magnetic sheet and the steel flexible sheet was enough to worsen the grip, and allowed the steel sheet to flex as it pulled away from the FEP.

But hopefully it was a 1-off.

Good luck. I can confirm that this scenario could warp the print as it was what happened to me, but if it were happening it should be visually obvious as once the metal plate starts to flex and peel away the resin infiltrates and prevents it from re-attaching so the sheet or plate would be visibly peeling away at the end of the process.

After 2 prints, the magnetic sheet is still attached and the warping happened again but it seemed to develop after the print was finished so I think it's a problem with the ambient temperature changing between drying and curing. I'll keep trying.

EDIT: yes the magnetic sheet seems to be working okay now and isn't coming unstuck. The warping I had is intermittent and probably for other reasons

 cattyandco wrote:
After 2 prints, the magnetic sheet is still attached and the warping happened again but it seemed to develop after the print was finished so I think it's a problem with the ambient temperature changing between drying and curing. I'll keep trying.

EDIT: yes the magnetic sheet seems to be working okay now and isn't coming unstuck. The warping I had is intermittent and probably for other reasons

Are you printing large, thin objects like a plane? I print a lot of terrain, specifically at the moment buildings, and I often find the floors warp after printing if they aren't anchored in place by walls on 2 or more sides. I usually leave a heavy object (like the horus heresy rulebook) on top before and after curing them in my curing station to encourage them to stay flat. It is also possible to bend them back even after curing by immersing the print in hot water from a kettle for a short time, removing and bending it carefully back into position with slow, steady pressure, then cooling under tap water and then leaving with a heavy object on for a while. Don't try to bend back without the hot water as the brittle resin will just snap.

I'm not sure why this happens but I've seen a suggestion that when resin cures it shrinks a bit and if the object is a flat plane then that can cause it to warp.

If you do find a better reason and solution do let me know

 Unknown_Lifeform wrote:

 cattyandco wrote:
After 2 prints, the magnetic sheet is still attached and the warping happened again but it seemed to develop after the print was finished so I think it's a problem with the ambient temperature changing between drying and curing. I'll keep trying.

EDIT: yes the magnetic sheet seems to be working okay now and isn't coming unstuck. The warping I had is intermittent and probably for other reasons

Are you printing large, thin objects like a plane? I print a lot of terrain, specifically at the moment buildings, and I often find the floors warp after printing if they aren't anchored in place by walls on 2 or more sides. I usually leave a heavy object (like the horus heresy rulebook) on top before and after curing them in my curing station to encourage them to stay flat. It is also possible to bend them back even after curing by immersing the print in hot water from a kettle for a short time, removing and bending it carefully back into position with slow, steady pressure, then cooling under tap water and then leaving with a heavy object on for a while. Don't try to bend back without the hot water as the brittle resin will just snap.

I'm not sure why this happens but I've seen a suggestion that when resin cures it shrinks a bit and if the object is a flat plane then that can cause it to warp.

If you do find a better reason and solution do let me know

It's all ordinary miniatures and things like accessories for G.I. Joe figures - nothing heavy or difficult. The overall picture at the moment is that since moving to a magnetic build plate, around 10% of the items on a plate fail and these are usually localized to one area near the middle - but I don't think it's the same area. It's difficult to tell because each batch of models is arranged differently, the magnet and plate and FEP all align slightly differently for each print, and some of the successful prints might be affected but not noticeably. The failures are also inconsistent: sometimes nothing prints, sometimes the supports print and the model comes off, and other times there is delamination - all in an area around half the size of a playing card.

Last time I tried with a heat mat underneath. My ambient temperatures are normally well below the recommended range but normally on the warmer days when I print I'm getting the printer to 18-20 degrees, which used to be okay.
I've re-checked the levelling, and it might be worth improving for next time but it's within a couple of degrees of being perfect.
I'm worried the magnetic plate might flex during printing. Or that the adhesive I've used might bulge in places. I could watch the former (for ages, with my respirator on) but it might be too subtle to notice, and the latter... I guess I could check it with the laser level.

The LCD screen is generally damaged and worn so probably I'll try replacing that next and going back to a normal build plate

Replacing the LCD screen seems to have worked. I may try and go back to the magnetic sheet but the weather has gotten cold so probably it will be next year. Overall with these machines I think there is enough to go wrong with them anyway without the magnetic sheets. My particular one was a very badly-designed solution to a very badly-designed product.