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phil-t

Warped Glass Bed UM2

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After getting to grips with the UM2 (thanks to this forum), I've just found a bit of an issue.

I noticed that larger prints had a really uneven first layer, I've been experimenting with 0.3/0.2/0.1 bottom layers and levelling the bed. After a while I've noticed that while I can level the bed using the manual tweak of the screws to just dial in a perfect perimeter thickness, I'd get odd patches of infill on the first layer that looked like the head is miles away from the surface.

On inspection, I've noticed that

A. The levelling screws are slightly proud of the aluminium heated plate, for example, the best one is:

DSC08648

So I guess a bit of additional countersinking is in order, and the aim would be to be slightly under the surface?

 

B. The glass is warped! - I was shocked to see it's actually so obviously bowed by a mm or more, for example, if I take a ruler, and take a picture of the glass with the ruler on it, then turn the glass over and take another image (to rule out any issues with the ruler not being straight), I get:

DSC08656 Small

DSC08652 Small

 

I've already phoned some local glass places, but they all want £30-£50 for a one off ground edge toughened glass which shocked me, then I wondered why I was just faced with spending £10 for a decent countersink bit, and up to £50 on glass which may well have sagged in the middle due to being supported on the proud bed levelling screw heads, so would anyone think this is a case of pleading with UM support to see if they can help out?

 

 

 

 

 

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Thanks, I know support are snowed under reading other threads, so I usually ask here first since you lot are very knowledgeable! But as it seems like the answer to my issue is going to cost a bit of money I've raised a support ticket to see what can be done.

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I would say ask here before support (you'll get faster answers).

The counterSink screws should be lower can you screw them back?

bvU9j91.png

As for the glass plate, if your machine is still under warranty you should probably contact support to get a new one.

If the warranty is off then you can buy it directly from the store:

https://www.ultimaker.com/products/um2-parts-print-table-glass

 

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I've wound up the spring tension (which is effectively pulling that screw head down) quite high, and it's clear the countersunk hole diameter is a shade too small, or the screw heads are a shade too large!

I work next door to a company who sell fixings amongst other stuff, I'll see if they have some M3 x 20mm countersunk bolts in to try, if not I have found a countersink bit in work, which I could try.

I think I'm correct in saying I need to address the proud screw heads before thinking about new glass, since that is more than likely the reason it has bowed in the middle?

 

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Yes i think it would be better to resolve that before risking to damage a new plate, it's odd though that it would bend that much...

Maybe try to unscrew the countersunk bolts and see if something is preventing them to be tightly screwed? (maybe there's some kind of residue?). Or try to unscrew the leveling screw to a maximum (you'll need to re-level the bed). And see if it's not due to to much tension?

 

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Unfortunately this is a known issue lately, the countersinks simply aren't deep enough. Besides causing the glass to possibly be slightly bowed when clamped (not like your glass Phil that seems to be permanently bowed) it also leads to the bed heat not being uniform across the bed.

If you're able to get the holes countersunk yourself I'd go with that as it's faster and easier than disassembling the bed. But for the glass, yeah, I'd have Ultimaker send you a new plate because that's just weird...

I'll also echo Didier on the part of posting on the forum first. There are A LOT of helpful people on here. The forums have a lot more man power than the Ultimaker office and will respond quicker in most cases (timezones can be a thing though :) ).

 

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Your glass plate should be replaced by Ultimaker straight away, they won't have any problems to send you one I believe but it might take some time (technical support is pretty slow)

Regarding screws, just take a dremel and grind them down

IMG 0461

IMG 0498

 

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Buy the countersink. You will use it for other things. Maybe not this year but I found mine to be incredibly useful for many projects. And it deburrs holes also. It's just a handy, cheap, light weight tool.

I suspect it's impossible to permanently bend the glass due to the screws. Of course you could flip it over and see if it corrects, lol.

Like someone else said you need to countersink those holes or the air gap will cause other more serious problems (bed at wrong temp).

UM Support can send you a new bed but it will probably take a few weeks. It's easy to open a ticket. There are probably large profit margins - just do it. Don't worry about it.

As far as buying tempered glass, what is the price for ordinary glass? I hear that works fine.

 

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People say that really old glass windows are thicker at the bottom because glass is a liquid. Supposedly when you go through the math you would have to leave that glass vertical for thousands of years so I don't think it got bent inside your machine.

 

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Thanks again for all the great advice..

I found a countersink bit in work that I borrowed, I removed the levelling screws, and the heated bed cable retaining clamp and use the countersink in a screwdriver handle (it has a hex shank) and did all the screw holes by hand.. It took 2 hours to do the glass retaining screws and bed levelling screws, but all is nice and flush now!!

Just for a laugh, I have indeed turned the glass over so the bow is topmost and am doing some test prints and I'll keep an eye on it whilst UM support get back to me! At least I'm OK for small jobs in the centre of the glass! you never know, the heat/head pressure on the first row might magically bend it back over time!!

I'll phone around some more places tomorrow to see if I can get any cheap deals on glass, it's the rounded corners (needed for clearance with the front clips) and polished edge (to stop any cuts) that seem to add that bit more cost, but I'll see what I can find!

 

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In London I had 2 pieces of picture glass cut and ground for £3 - the edge grinding is normal. I guess a quick chat with the grinding guy would easily round them if needed (mine was for a UM1) or go back to clips :) (just while you wait)

Mine is not on a hb so I would heat them up slowly, and possibly not use the fridge - though you don't hear much about cracking. (get 2 :))

James

 

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I also have a warped glass bed and warped heated bed, I had been wondering why some prints were underextruding on certain sections of the bed and not others, then I had the idea of checking if the bed was flat and it wasn't, the photos below show the glass bed one way up and then flipped and also the heated bed warping

The stats counter has never been reset, had my machine since Aug 2014

Very annoying, out of warranty but hoping Ultimaker will sort this problem out for me.

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p><p> <img src=[/img]

p><p> <img src=[/img]

p><p> <img src=[/img]

img]<img src=[/img]<a href=IMG_9285_zpsz8a1claf.jpg' alt='IMG_9285_

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Also just to add, I don't think the screws have anything to do with it as my glass bed warped up wards not down. I have some tiny scratches on one side and that side always faces down, the smooth side has warped upwards.

Edited by Guest

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Ultimaker won't replace my bed! I think that's really bad considering the amount of time I've used the printer, so I would advise other people to check their beds, or be prepared for them to possibly warp!!!

Just received a brand new glass bed replacement from 3DGDIRE (uk ultimaker support) and that also has slight warp already, straight out of the packaing, I can upload photos to show.

Edited by Guest

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