Glass Bed Attachment.

So I decided to switch my acrylic bed out to a glass one. Mainly because:

1. It was really hard to get the PLA off the acrylic bed. Next time I'll just use painter tape.
2. Sagging on the sides. I had a few ideas but none that would work with those L-Channels.

I choose 1/8" glass (also known as DS glass) from True Value Hardware. Definitely a better choice than single strength and weighs noticeably less than 3/16". I also switched out the L-channel with C-channel from Home Depot. I feel like the sides of the C-channel makes them more sturdy. I used 18" lengths for the bottom railings as well as the glass framing.

I like the result. I think it looks clean, although that won't matter once the heat bed is installed. To connect the C-channels, I got some smaller M4 bolts and also used hex nuts and washers to tighten them onto the C-channel so I wouldn't have issues when calibrating. I left everything else the same, except took a plastic pipe cutter to the butterfly ends of the nut to turn Mickey Mouse into a sleeping Batman. Those butterfly ears made it impossible to calibrate. But now it's not a problem and with the hex nuts holding the bolts in place. It doesn't move on me like it used to.

To keep the glass in place I used some picture frame spring clips. That kept the glass away from the end bolt, and pressed it to the top of the C-channel. I did 3 on each side just to be safe.

Because this is glass, I don't need to put a frame on the sides. No sagging with glass. My future plan is to take an 18x18 Monster Board heat bed and place it below the glass. I'll use the spring clips below the heat bed on the frame to sandwich it to the glass. And I'll add four spring clips on the railings, to add pressure spaced evenly around the center of the board. I placed those in the top photos to give an idea of where they would be located.

I hope this helps someone else with their mods!



Looks beautiful. Added benefit is that if I do this, I'll probably have a messy cut edge of the glass and it won't be visible to the eye because it'll be inside one of the channels!

It took a little bit of re-reading and scrutiny to understand how you handled locking the bolts into the C channel and leveling the bed, but now that I understand, nice work.

Glass definitely allows you to print at higher temperatures, and if you print the first layer above 200 degrees the print won't be bonded to the bed almost permanently, but glass is very fickle when it comes to adhesion and a heated bed definitely will help.
Great design. Looks good.

Did you make the tension spring ribbons yourself or purchase them? If the latter, what are they called?

Nearest match I can find online are half moon tension springs but they'll require enough tweaking that I'm not sure they're worth buying.
Justin already answered these questions for me so I'll pass on the info:

The full name would be something like "picture frame spring clip" or "metal frame spring clip". I went to Michaels and asked an associate at the framing desk and she gave me a few.

Or some sites if you want to buy online:

The C Channel is .5" x .5" etc... It comes in an 8ft length from homedepot for roughly $10. The 8ft is enough for all 4 lengths.
]Don's glass bed modification inspired me to make the change as well though I did mine a bit differently. I wanted to accomplish a few things:

- Avoid wrestling with the printer while trying to scrape off PLA prints.
- Eliminate bed sag.
- Print with ABS or high temp PLA without worrying about first layer fusing to bed.
- Ability to easily remove the bed so I could detach prints without molesting the printer.
- Reduction in total bed weight to ease skipping issues and allow weight for an eventual heated bed.
- Stop my print head from melting holes in the acrylic bed time I homed the Z access.

I used an old piece of broken glass I already had so my initial result looks much less living-room-worthy than Don's but my printer is in the garage so I'm OK. I can easily change out the bed to another piece of glass, the original acrylic or anything else without effecting bed level. This allows me to set a stuck print aside to deal with later while I print anew on a fresh piece of glass.

For PLA, instead of painters tape I use a very thin piece of acrylic taped on the glass. That way I can easily remove the print without any tape sticking to the bottom. I also use less tape and don't have to spend the time to make the tape flat against the glass. The bend of the acrylic helps pop off the print without having to wrestle with the bed while it is attached to the printer.
[attachment=0]New Glass Bed.jpg[/attachment


This test bed is smaller than the gMAX build size but right now I not printing anything that large. Using the smaller glass saves weight and a larger bed can be swapped in about 15 second. I used the double strength glass that Don mentioned (3.5 mm thick) but have a full sized bed that I will try with single strength glass (2.5 mm thick) to save even more weight. An 18" x 18" square of single strength is about $7 and Lowe's or Home Depot. Lowes cuts the glass for free.

I considered using aluminum C rails like Don but ended up using L rails like the type that came with my printer, though mine are slightly longer on one end of the L ($9 at Lowe's). You could make this change using the top two L rails that currently hold up the acrylic bed though they are a little narrow.

I drilled holes in the glass using a Dremel tool and a diamond tipped bit so that the glass fits snuggly over the spring bolts. I never drilled glass before but it worked. 3D printing is taking me to all kinds of unexpected places. You could also just clamp the glass (or anything else) to the top of the L rails but then would need to make the bed slightly shorter. I have a clamp shown in the picture but with my drilled holes I don't need it. I can just pull off the glass and replace it with anything else that has holes drilled in the same place.


Printing on a thin piece of acrylic will allow you to complete the sometimes messy work of print removal without jarring the printer and/or harming yourself with a sharp instrument. Adjust the Z axis for the height of the acrylic. Here I've use a small piece for a small print but this will work with any size. This piece was cut from the front cover on an old framed poster. The most expensive part of the whole project was hiring the hand-model to pose for this picture.

One final note, I had to add spacers to the spring bolts because the threads did not go down far enough. You can see these in one of the photos. After I completed my first print with the new bed last night I removed the acrylic piece, warped it a bit and the print popped right off.

Thank you for reviewing my nerdy adventure.


In the last posts I credited the Don for the glass bed upgrade. I just realized it was Justin. Sorry Justin, great design. Thanks for the inspiration.

Awww, thanks guys. Well yer making me feel bad cause I did more and didn't tell anyone.

I don't know about any of you, but after a while my bed goes off the v-slot track because that acrylic piece that is pulled by the y-axis starts to bend. That means the x-axis is not level, or the y-axis, because it's not sliding correctly. And I'm always trying to level the bed again or retighten parts to resolve it.

Well I got tired of it and decided there had to be a way to fix the acrylic piece. I was going to replace it. But I didn't know where to go or how to make sure I drilled the holes at exactly the right places. Then I decided rather than replace it, I could strengthen it.

I have a bunch of misumi 1515 t-slots all 240mm. I took two and screwed them in horizontally where the L-channel was for most of you (which I replaced with a c-channel). I then screwed the c-channel on top. This keeps the acrylic of being able to bend.

I'm sure there are easier or better ways to do this. But I was just using what I had around the house to resolve the issue. I hope it helps someone.



Ouch. Okay, I just saw the photos. What happened to the glass? Seriously, picture frame spring and c-channel. Replace that glass! I am using double strength. Lowes doesn't sell it but True Value hardware does and they cut as well. However 3/16 will be sure the glass won't bend. I just didn't want the weight. I'm reconsidering.

What happened to the glass? Seriously, picture frame spring and c-channel. Replace that glass!
If you are referring to my crooked glass, I just used an old piece I had laying around. Looks = 0 but functionality = 10. I bought a new, 18" X 18" piece that I'll put on when I get the chance. The picture frame springs seem like a great way to hold the glass in place but they make it cumbersome to remove the glass sheet. If I'm having trouble removing a print I like to take the glass off so I don't have to jostle the printer. Plus, I can easily swap in a smaller piece of glass for most prints that don't need the entire build space. The reduces bed weight. There are many ways to skin a cat. In this case it looks like we've both figured out a way to make a glass bed work.

Upgraded to glass bed and U-channel supports, then added aluminum support plate to fix the bed wobble as it reversed Y direction.

Now I'm having zero luck getting the first layer to stick. Gave it a try for a few days, then ordered the 18 x 18 Monster Heated bed. :)


Glue stick, my friend. A light coat and print the first layer at 210. The higher you go, the better the adhesion. I'm printing fairly well onto a cold bed at 230. 210 worked for me also, but the Z-height had to be fairly accurate.

And Don, I'm glad to see a printer that is living room-compatible. :)
For any of you fella's printing on glass, are you having any problems with the first layers warping? I'm using glue stick for adhesion, but if I try to print anything flat larger than about 3" it starts curling up and warping badly. Wasn't having the issue on sanded plexi so wondering if there is a trick I'm missing.

Are you printing with PLA or ABS? I converted to a glass bed a couple of months back but I still print on thin acrylic that I tape or clamp to the glass. This hybrid method takes advantage of the sticking power of the acrylic and the flatness of the glass. The acrylic I'm using is very thin, cut from the protective covering from an old framed poster. It's easy to take off so I can forcefully scrape off a print away from the printer. I can also bend it which helps pop off a print. If I break the acrylic, there are plenty of replacement frames sitting at the Goodwill.

Using PLA and a print above say 5", I really need to hold down this thin acrylic. The print sticks so well that it bends any lightly secured acrylic right off the glass. But if I clamp everything down, it works great. This doesn't directly answer your question but at least lets you know that you are not alone when I comes to removing prints from acrylic. My scarred fingers are testament. In one second you are forcing the razor blade under the print and in the next you've almost cut off your finger. That's why I switched to this hybrid system but I still have problems from time to time.


I'm printing purely PLA. No problems with warpage when I use the thin layer of plexi like you are doing, only when I print directly on the glass with using a thing layer from a gluestick.

No razor blade cuts for me yet, but I did get a nice burn from the glass when the heated nozzle sat on it for about 15 mins. I was doing some last minute adjustments when I stopped a failed print and startled over so the nozzle was right on the glass. I stepped away to take a phone call and forgot all about it. 15 mins later, thing was freaking HOT!!!

- Other Chris