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So I have pretty good first layer adhesion, but this is ridiculous...

Left a print over night (6 hour print) - looks absolutely beautiful.

Lifted the print up - didn't need any scraper, it just lifted right off - and a chunk of the boro glass was stuck to the part.

120 bed temp with some juice.

Seems like this shouldn't happen...

Thoughts?

Looks to me like the result of a defect in the glass. That may happen with regular annealed glass, but shouldn't happen with borosilicate glass.

g.

I would be curious if anyone else runs their bed temperature that hot and have experienced failure of the glass.
The glass should be able to withstand 120 Centigrade but this failure makes me wonder, is this just an isolated
case or not?

I put it at 120 because only the very center of the glass is at 120.

Even 1 inch away from the center and it drops to 112-115. A few inches from the center and it drops to 100 or lower.

Also, the safe working temp of boro glass is well above 200C...

I use plain 1/4" glass with hairspray.
I have had pieces of glass come up with print IF I use to much hairspray. Normally no problems.
I use 75c

I don't think it was high temp, just to good of a bond with the abs juice.

give hairspray or white glue stick a try.


hopefully you can use the other side of that expensive piece of glass!
that's why I use the cheap 1/4" glass from the glass shop... no big deal if it breaks.
I don't even bother getting it cut round, a 10-1/2" square works just fine for me.

I don't think the glass is going to work anymore. The crack goes all the way through, so I have a feeling it will break completely if it's heated up again, or has any sort of pressure on it. I may be able to use it for PLA, but I don't print much other than ABS.

John just said they would replace it, so that's excellent.

I normally use PET tape with juice, but I wanted to print last night and didn't want to wait for the PET to cure... I guess I will continue my PET using ways.

I've tried hairspray, but for the 2 prints I make that we sell to customers, it's not strong enough to prevent warping/curling.

Haven't tried glue, but haven't really felt the need to use anything else.

In related news, I just came across some 3/16" and 1/8" glass refrigerator shelves. They're labeled as "tempered", but that could really mean a lot of different things.

They are large and flat, and if I can properly cut them, they would seem to be excellent build plates.

Anyone know how to test if they're able to handle thermal expansion without heating them up?

Tempered glass should be ok thermally but you can't cut it. As soon as the surface is broken by cutting or chipping it, the whole piece will "explode" into small pieces. It's manufactured under high stress for safety. Any break will release all the stress catastrophically reducing it to small bits. The small bits will not be very sharp and it will not produce long shards that could stab someone. I found that out the hard way while sandblasting a design into a piece of tempered shower door glass. Everything was going great until I got just a little too deep with the etch and BANG! Buckets full of small glass confetti. That was fun.

That sounds almost like a magic trick.

There are a few things you can do to improve your print quality. I noticed you're selling printed parts to customers, so what I say will have that in mind.

You may want to do some sort of enclosure mod. It will keep the temperature stable and conserve electricity, since your heating elements won't have to work as hard.

Another good mod would be an effector-mounted fan duct. The idea is to have something that evenly radiates air over your part, which will improve print quality. I recently started trying to print vases, and I've found it impossible due to any sharp edge curling up and ruining the print. However, I found that pointing a small fan at one side of a vase results in that side NOT curling, so I'm designing a fan duct to go with my Budaschnozzle. I expect great things from it.

Finally, give PLA a shot. The bad news with PLA is that it has a learning curve, especially when it comes to extrusion. I had bad luck with the SeeMe hotend, OK luck with a J-head from hot-ends.com, and really good luck with a Budaschnozzle. I use the settings in the KISSlicer subforum and get good retract performance. As for good news - bed and hot end temps are both significantly lower (and you can do without a heated bed - lots less electricity still), it pretty much never delaminates, parts don't die in the middle of a print because of heat issues, it's less prone to curling up at the edges, etc. It's also tougher stuff than ABS. I've been working on some tower brace clamps recently, and I found PLA is much better for anything that has to bear any kind of load. At 20% infill, my clamps were both strong and lightweight. They flex in the way they're supposed to, and they hold up to the forces they're supposed to. With the same exact part printed in ABS, I had to use 50% infill or it would make awful cracking noises any time I flexed it. Even then, it flexed more (in the worst place) and just didn't seem as strong. If you're printing gears and other things like that, the increased stiffness is definitely worth looking into.

Thanks for the reply. I actually used to use PLA. I had an airwolf 3d and printed the gears in PLA, but they're too brittle and our product generates too much heat. The PLA got too warm.

Also, we lightly sand the parts, then apply BJB infiltrant epoxy with a vacuum bag, and then bake in an oven.

The result is an incredibly strong gear (we use them in our electric skateboards, www.alteredusa.com) that looks as clean and smooth as an injection molded part.

I bought the Max so I could print 7-8 parts at a time. So far, the most I've printed at one time is 4, but I'll be trying a full plate here soon as I'm really getting it dialed in with the new .35 nozzle.

I've seen glass plates do that, especially with ABS juice. But it's likely a result of a small defect in the glass. What probably happens is that as the part cools and shrinks, the weaker glass breaks rather than releasing the print.

That's fascinating. How do you get the epoxy on without changing the gear tolerance?

I apply about 15g of epoxy to each 50g raw part. after vacuum bagging for about 40minutes, almost all the epoxy is absorbed into the part, with a thin layer still on the surface.

When you bake the it, the epoxy becomes much less viscous and the abs expands a bit. Any excess epoxy either drips off into the drip plate, or is absorbed by the part. If I spot any excess on the gears, I brush it off. (Working time is about 2hours on the epoxy)

After epoxy, the parts weigh between 59-62g, and the outer coat is well within the tolerances of our boards' needs.

Rather than start my own thread...

Cope, that wasn't a chip. This is a chip.

[img]http://www.simonlockwood.net/linky/3dp/maxglass.png[/img]

90º on the bed. Part was 150 across, 50 deep, 25mm thick.

ABS print, abs juice on the glass. Normally I chisel the part straight off but this time I let it cool down first to see if it would make things easier. It sure did

Have pinged Support@seemecnc and will see what they say, hoping they'll play nice and take the hit on the shipping fee otherwise I'll be looking for a local glazier to cut me some new ones.

Captain Starfish wrote: Have pinged Support@seemecnc and will see what they say, hoping they'll play nice and take the hit on the shipping fee otherwise I'll be looking for a local glazier to cut me some new ones.

I got a local glass cutter to cut me a disc of 1/4" oven glass. It was twenty something dollars.

I think ABS juice is not a good idea...
It sticks to the glass very well and has a different contraction characteristic when it cools down. Over a larger area it puts tremendous stress on the glass and will find any flaw that might be in the glass.

I've only every used Elmers glue, but I routinely let it cool over night, even with very large parts. The parts will pop right off the glass as they are cooling down and I can simply pick them up in the morning. The glue gets pulled from the glass so I am confident there is no excessive stress on the glass itself.

Seems like ABS juice is trouble.....

wonderemporium wrote:Tempered glass should be ok thermally but you can't cut it. As soon as the surface is broken by cutting or chipping it, the whole piece will "explode" into small pieces. It's manufactured under high stress for safety. Any break will release all the stress catastrophically reducing it to small bits. The small bits will not be very sharp and it will not produce long shards that could stab someone. I found that out the hard way while sandblasting a design into a piece of tempered shower door glass. Everything was going great until I got just a little too deep with the etch and BANG! Buckets full of small glass confetti. That was fun.

Then SeeMe needs to put the screws to their borosilicate supplier, because my original glass bed had several chips break out of it - EXACTLY like the chip pics in this thread - before it finally cracked in three large pieces while cooling. I've never run it hotter than 95c, that's all my Onyx will get up to. I also remember several other posts where people have had pieces come off. I replaced it on my own dime because I figured I'd been playing too rough getting prints off, but it sounds more now like a bad source, or at least a source with a noticeable failure rate.

Bummer, was kinda hoping John would help me out with this but I guess tyranny of distance just makes it silly expensive so nothing forthcoming.

Never mind.

Local glaziers will sell me 4mm mirror glass or 6mm furnace glass for a million bucks a piece. Finding a replacement isn't going to be as easy as I thought, one of the joys of living in the world's most remote capital city I guess.

Or do I just give up on glass? I have an order going to the laser cutter for 3mm plate 6061 aluminium parts in a few weeks, I guess I could just flip the buggered glass plate in the meantime and slip a couple of 300mm circles with notches off the end into the order...

How are people finding aluminium as a build surface when it comes to getting parts to stick to and release from the plate?

The build plates are made from Borosilicate glass (Pyrex), not any form of tempered glass.

The "grip" strength of ABS juice in conjunction with asymmetric cooling will exploit invisible fracture lines in ANY glass material.

Use hairspray or glue stick if you're printing with ABS.

Here's a good source of 12", 1/4" mirror: http://www.dullesglassandmirror.com/sto ... aspx?ss=30

That took me all of 10 seconds to find. (Note, searching for "online glass shop" will give you VASTLY different results than "online glass sales". TIL! *laughs*)

g.

geneb wrote:The build plates are made from Borosilicate glass (Pyrex), not any form of tempered glass.

The "grip" strength of ABS juice in conjunction with asymmetric cooling will exploit invisible fracture lines in ANY glass material.

Use hairspray or glue stick if you're printing with ABS.

Here's a good source of 12", 1/4" mirror: http://www.dullesglassandmirror.com/sto ... aspx?ss=30

That took me all of 10 seconds to find. (Note, searching for "online glass shop" will give you VASTLY different results than "online glass sales". TIL! *laughs*)

g.

Those mirrors were a great find! Thanks!

You're welcome. Now search for "online glass shop". It's...educational.

g.

I was printing Nylon with a brim on a piece of 3/16" glass with scotch glue stick at 80C, and my plate shattered. The warpage of the nylon shattered it :O

Standard window and mirror glass was not engineered to handle thermal stresses. The borosilicate/high temple glasses are explicitly designed for this. Last year I posted in my build thread the shattered glass build plate that occurred on heating. A piece of glass the size of a matchbook hit the wall. If it had gone the other way, it would have hit me. Please be careful with glass that is not designated for hot applications.

Cheers,
Michael