Borosilicate Glass Heatbed Mod

Share any mods you have made and the awesome results.

Moderator: Elijah

PrintMan
Posts: 53
Joined: Wed May 15, 2013 12:17 pm

Borosilicate Glass Heatbed Mod

Postby PrintMan » Thu Jun 20, 2013 2:54 pm

Hello all,

First, I just want to say this is a great board, and I am definitely going to use some of the stuff I have found on here.

Moving onto the subject of my post, I recently added a custom borosilicate heatbed to my TAM printer. The way I did it, I used the RAMPS 1.4 board to control the heatbed, upgraded the power supply, and put in a 10A fuse to the heatbed to protect RAMPS if heatbed goes bad.

In a nutshell, I did the following:

- replaced 12V @12.5A OEM power supply with a 12V @25A power supply that was able to fit in the TAM power supply bay. The 25A power supply does have a small integrated fan though where the 12.5A power supply did not need one.
- replaced TAM plastic bed with the following stack:
= borosilicate glass on top (very flat and low thermal expansion makes it resistant to temp changes)
= 1/16" thick aluminum plate same size as glass and below glass (helps conduct heat evenly from smaller heatbed PCB to larger glass
= Mk2a Heatbed PCB below aluminum plate
= Aerogel insulation between Heatbed PCB and Bed Woodframe on TAM (aerogel is an excellent thermal insulator)
= Millboard Frame ( holds Glass, aluminum plate, and Heatbed PCB and interfaces with TAM's bed locking screws, millboard is a pretty good thermal insulator )
- Mk2a Heatbed PCB wired in series with 3 in parallel 1 ohm resistors to bring the amperage down to 7.5 - 8 A instead of 10 A (read some accounts that RAMPS 1.4 may not handle a headbed as well at 10+A if it is supplying the curent)
- Above feature allows me to put in a 10 A fuse wired in series with the bed thus protecting the RAMPS board if something bad happens with the heatbed
- Heatbed controlled by the RAMPS board. I did not have to change anything in the firmware; I just had to connect the heatbed power and heatbed thermistor to the correct connections on the RAMP 1.4 board per the RAMPS 1.4 documentation. I did have to add Gcode to slic3r to heat the bed to 60 degrees C at the beginning and then turn off the bed.

This design heats to 60 degrees C in about 5 to 10 minutes. Due to my decision to reduce the amperage draw of my heatbed, if I try to heat to 110 degrees C for ABS, I am not sure if it would make it. It took 40 minutes to reach 96 degrees C. I doubt I will be printing with ABS, so this is okay for me at least.

Prints with this are awesome so far, no warp and I am guessing it will be easier to start 0.05mm layer thickness parts although I have not tried that yet. Also, the first layer of PLA sticks nicely to the glass.

It was probably overkill to use aerogel on the bottom. It is supposed to be an amazing thermal insulator, but it is not the most pleasant to handle. It dries the hands and is dusty.

Below are pics of:
- the 12V @ 25A power supply attached to the rear wood panel with the wood panel partly assembled
- composite of bed being assembled
- composite of assembled unit viewed from the top and bottom
= 12V / 10A fuse can be seen in the lower left of this image( the black rectangular rubber box with a wire on both sides, the box has a cap which can be opened to access the fuse)

If you have questions about something, just let me know.

13060013.jpg
12V @25A power supply attached to rear wood panel with panel partly assembled
13060013.jpg (927.29 KiB) Viewed 5925 times


bed_assembly_composite.jpg
Composite of Assembling Borosilicate Heatbed
bed_assembly_composite.jpg (670.33 KiB) Viewed 5925 times


heatbed top and bottom view.jpg
Borosilicate glass heatbed viewed from top and bottom in TAM
heatbed top and bottom view.jpg (812.56 KiB) Viewed 5925 times

watsonstudios
Posts: 143
Joined: Wed Dec 19, 2012 4:32 pm

Re: Borosilicate Glass Heatbed Mod

Postby watsonstudios » Thu Jun 20, 2013 4:37 pm

I wish you luck on your heated bed. I did not fair too well with mine. Everything worked great, just the prints did not print straight vertically because of the difference in temp. The PLA tended to shrink at different rates vertically because of the heated bed. The taller you print, the more you will see what I mean. Here's a link to my thread on my heated bed mod. I used 3/16" Borosilicate glass on mine.

viewtopic.php?f=7&t=417&start=20

PrintMan
Posts: 53
Joined: Wed May 15, 2013 12:17 pm

Re: Borosilicate Glass Heatbed Mod

Postby PrintMan » Thu Jun 20, 2013 8:26 pm

Hmm, that doesn't sound good. Thanks for pointing this out watsonstudios. I didn't notice that part of the thread. So far, I have seen all positive, but I have been printing smaller parts, no larger then 3.5" x 2" x 2". I was getting warping if I would print two of these parts at the same time without the heatbed, viewtopic.php?f=8&t=482 . Same thing with printing one of this part, http://www.thingiverse.com/thing:88407 , that my brother asked me to print. Once I used the heatbed, both parts were absolutely flat.

I have not printed any large parts though. I am going to do that and will post what happens here. I will be busy this weekend, so this will probably not happen until mid next week.

PrintMan
Posts: 53
Joined: Wed May 15, 2013 12:17 pm

Re: Borosilicate Glass Heatbed Mod

Postby PrintMan » Thu Jun 20, 2013 8:42 pm

Oh, and my borosilicate glass is 1/8" thick.

Charles Xavier
Posts: 82
Joined: Mon Apr 22, 2013 10:23 am

Re: Borosilicate Glass Heatbed Mod

Postby Charles Xavier » Fri Jun 21, 2013 6:39 am

Looks good! About how much did the whole thing run you? And where do you get your aerogel from? I've been looking for better sheet insulators.

PrintMan
Posts: 53
Joined: Wed May 15, 2013 12:17 pm

Re: Borosilicate Glass Heatbed Mod

Postby PrintMan » Fri Jun 21, 2013 9:21 am

Thanks Charles.

Yes, the whole thing was kind of expensive at $220 before shipping. If I could have gotten smaller quantities of millboard or aerogel, that would probably had decreased the cost by ~$30. Then instead of replacing the power supply, I could have gotten a second lower power one for maybe ~$45 saving another $40. It would not be as clean though. But then it would maybe be $145 before shipping. Anyway, the full BOM is below along with the URL link for the aerogel which I got off ebay.

Screenshot of BOM:
ScreenHunter_50 Jun. 24 21.25.jpg
ScreenHunter_50 Jun. 24 21.25.jpg (110.57 KiB) Viewed 5857 times


Untidy List of BOM:
Part Supplier P/N URL
Millboard -1/8" thick 39" square McMaster 9362K11 33 mcmaster.com
Borosilicate Glass 1/8" thick 260x230mm Torstenson Glass Company N/A 25 http://www.tglass.com/technical.htm
Aluminum Plate McMaster 5865T11 6.93 http://www.mcmaster.com/#5865t11/=nago1w
Silica Aerogel - .4" x 13"x57" ebay.com N/A 25 http://www.ebay.com/itm/Aspen-Aerogel-S ... 337d92e6d2
PCB Heatbed MK2a - no 4pin conn ebay.com N/A 24.95 http://www.ebay.com/itm/3D-Printer-PCB- ... 4ac497d9ff
Kapton tape 3/4" x 5yds McMaster 7648A714 8.14 mcmaster.com
Kapton tape 1/8" x 5yds McMaster 7361A11 5.3 mcmaster.com
100k thermistor - custom table for firmware http://reprap.org/wiki/Thermistor#EPCOS ... 0G1104F.29 Ultimachine UMTHR100 2.75 https://ultimachine.com/content/thermistor-100k
Power Supply 12V @ 25A TRC Electronics PLF300F-12 86 http://www.trcelectronics.com/Cosel/pla300f-12.shtml
2.54mm pitch 2 pin connector Ultimachine UM1X2CBCN 2.5 https://ultimachine.com/content/254mm-1 ... kit-6-pack
Total 219.57
Last edited by PrintMan on Mon Jun 24, 2013 7:27 pm, edited 1 time in total.

Charles Xavier
Posts: 82
Joined: Mon Apr 22, 2013 10:23 am

Re: Borosilicate Glass Heatbed Mod

Postby Charles Xavier » Fri Jun 21, 2013 11:27 am

Thanks for the BOM and the pricing info! That aerogel looks nice, but yeah I wish smaller cuts were available.

jbrisbin
Posts: 80
Joined: Fri Mar 15, 2013 12:37 pm

Re: Borosilicate Glass Heatbed Mod

Postby jbrisbin » Sat Jun 22, 2013 2:43 pm

Your text describes the replacement supply as 25A, the link reflects that, but the BOM shows 18A.

Nice setup.

PrintMan
Posts: 53
Joined: Wed May 15, 2013 12:17 pm

Re: Borosilicate Glass Heatbed Mod

Postby PrintMan » Mon Jun 24, 2013 7:33 pm

Thanks jbrisbin, I just edited my previous post so that it says 25A for the power supply which is correct.

Charles, also just FYI, I used J-B Weld epoxy to glue two sheets of the millboard together to form the bed frame.

watsonstudios, I am printing a larger object right now. Hopefully, all goes well, and it finishes successfully. Then I will post pics tomorrow if everything goes well, and we can see if the walls are straight or not....

PrintMan
Posts: 53
Joined: Wed May 15, 2013 12:17 pm

Re: Borosilicate Glass Heatbed Mod

Postby PrintMan » Tue Jun 25, 2013 9:22 pm

Okay, I successfully printed this Castle scaled by a factor of 1.4: http://www.thingiverse.com/thing:33310

At least to my eye, the walls do look pretty flat. The bottom layer protrudes a little, but I think that is because the bottom layer was squeezed. I used slic3r and had it print a 1 layer skirt. I printed with 0.25 mm layers, but the 1 layer skirt only measured 0.15mm. So, when the printer was depositing enough material for a 0.25mm layer in 0.15mm of height, the bead had to widen.

Pictures are below. Let me know if this looks flat to you, watsonstudios, or if I am biased to my mod. :)

13060028.jpg
Castle still on bed
13060028.jpg (771.71 KiB) Viewed 5846 times


13060033.jpg
Arial view of castle removed from bed
13060033.jpg (938.1 KiB) Viewed 5846 times


large-towers-composite.jpg
Upper left shows profile of left tower, Upper center shows almost profile of left tower, Right center shows profile of right tower, Lower shows profile of front of left tower. Note the widened layer at the base possibly caused by a squeezed first layer
large-towers-composite.jpg (731.25 KiB) Viewed 5846 times


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