Welcome to the SeeMeCNC Community

So, I just bought the "PCB Heated Bed Rev B Blue" (Phebe I?) from the website a few days ago... lurking through the forums here has given me more questions than answers though.

I noticed a lot of you are using tempered glass and springs and such on your beds? The website says in addition to the board I need: Thermistor, Electronics, Wire (4 conductor 18AWG), screws, and high temp silicone glue... -- I'd just assumed you printed directly to the circuit board -- glad I didn't try that!

Any guides on how to put the thing together, and what all parts are that I'll need?

Further stupid question: can I solder the wire directly to the terminals or do I have to worry about it reflowing due to the heat?

Here are some pictures of how I assembled the Phebe I to my printer. So far, this has held and I have had no problems with it. Height adjustments are easy and simple, when needed.
http://forum.seemecnc.com/viewtopic.php ... hebe#p2708

Nice. I'd peeked at that thread before, but not all the way down to page 17!

So, it's tempered glass, right -- not just regular glass? (Any good suppliers? Size is 6.5" x 7" ?)

Is the air gap required?

Also, it doesn't make sense to me that you're using printed clamps for the heated glass -- shouldn't those "melt" ... or at least become soft and not hold the glass in place anymore? (Wikipedia says ABS "melts" at 105 °C -- how hot do you run your bed?)

I read on the reprap wiki that some people have gotten okay results with kapton tape in lieu of glass -- I think I'll try to start with that... and some wood underneath -- Also, if I do get glass... I can just leave the tape on there between the glass and the heated bed, right?

Honestly I don't know what type of glass this is. I was able to get 3mm glass from an old scanner that I took apart and cut to size.
So far it has not had any issues. I have heated/cooled this glass many times. The one thing I avoid is temp shock, no sudden changes in temp (specially when cooling).

Also, the bed runs at something like 125-135C, the ABS clamps are holding, no real problems. I do however plan on replacing them with something metallic and shorter/thinner because it is becoming difficult for my extruder carriage to move around them.

The air gap is required (in my case) because I don't have any other sort of insulation between the plastic bed and Phebe. If you place Phebe on the plastic bed it will warp the H-1 plastic bed.

Kapton tape is a good starting point for printing, but I am using ABS 'juice' (search for that on the reprap forum) and have had great success with it. Kapton tape is ok, but it is expensive to get anything larger than 2" in width, causes air bubbles and joint lines in the prints. If you get glass, remove the kapton tape from Phebe and put the glass directly on Phebe. Direct contact is best for heat transfer. Then you can place kapton tape on the glass.

Honestly I don't know what type of glass this is. I was able to get 3mm glass from an old scanner that I took apart and cut to size.

Whoa, nice reuse...! ...but, how did you cut it? I'm no expert, but doesn't glass just break? I had a hard enough time cutting plexi-glass with a jigsaw.

The one thing I avoid is temp shock, no sudden changes in temp (specially when cooling).

How slowly, in general, should one change the temperature of random bits of repurposed glass?

The air gap is required (in my case) because I don't have any other sort of insulation between the plastic bed and Phebe. If you place Phebe on the plastic bed it will warp the H-1 plastic bed.

So the wood block doesn't work as an insulator then? Or is it just not adequate enough on it's own?

Kapton tape is a good starting point for printing, but I am using ABS 'juice' (search for that on the reprap forum) and have had great success with it. Kapton tape is ok, but it is expensive to get anything larger than 2" in width, causes air bubbles and joint lines in the prints. If you get glass, remove the kapton tape from Phebe and put the glass directly on Phebe. Direct contact is best for heat transfer. Then you can place kapton tape on the glass.

So, no kapton tape between board and glass -- but, really? -- I should put kapton tape on top of the glass?

ABS 'juice' (search for that on the reprap forum)

Found this: "10mm of abs filament dissolved in 10ml acetone" -- sounds like the same thing as "ABS glue" -- You guys are putting this stuff on your print beds to avoid warping? I never would have thought of that.

Whoa, nice reuse...! ...but, how did you cut it? I'm no expert, but doesn't glass just break? I had a hard enough time cutting plexi-glass with a jigsaw.

I use a standard glass cutter, similar to the one I linked below. Since this glass is not tempered, it cut like any standard glass you would get from a LHS. I think the only benefit I get from a scanner/printer glass window is that I think its meant to handle more 'stress'. Meaning it can take more abuse then standard glass.

http://www.amazon.com/Red-Devil-106370- ... ass+cutter

How slowly, in general, should one change the temperature of random bits of repurposed glass?

I just let the bed heat it up as fast as it can and allow it to cool enough to be able to touch without any interference.
Normally it takes Phebe I about 5-7 minutes to heat up the bed to 125C and it takes about the same to cool to safe temps (I can touch without burning myself).

So the wood block doesn't work as an insulator then? Or is it just not adequate enough on it's own?

It does a bit, but not enough. Others have used the following item from McMaster-Carr for insulating the heated bed from the plastic bed and I hear they are getting good results.
http://www.mcmaster.com/#catalog/118/3522/=j2acoa

So, no kapton tape between board and glass -- but, really? -- I should put kapton tape on top of the glass?

Yep, no tape between the board and glass. What you put on top of the glass depends on what method you are going to use to get the ABS material to stick. You can use Kaptop tape, blue painters tape, ABS glue or other methods.

Found this: "10mm of abs filament dissolved in 10ml acetone" -- sounds like the same thing as "ABS glue" -- You guys are putting this stuff on your print beds to avoid warping? I never would have thought of that.

I am putting this on the glass surface to help keep the print stuck to the glass surface and the added benefit of helping keep edges from warping (sometimes warping happens and can't be avoided). My rough approximate mix of acetone and ABS is a 3:1 mix. I make batches in small plastic bottles that I get at a local beauty store that can handle acetone. They make for easy dispensing and cleanup. I usually fill the bottle 3/4 of the way with acetone and then the rest of the bottle with ABS chunks I have recycled from failed prints. Let the acetone dissolve the ABS and its ready for use. I usually try to get a milk like appearance to the mix.

I use a standard glass cutter, similar to the one I linked below.

Holy crap, that's AMAZING! I never knew there was such a thing! Found some instructions and a neat video: WikiHow - How To Cut Glass.

Can't remember, where I read it on here, but while lurking, I read that somebody had gone to the dollar store and just bought picture frames. Thought that sounded like a great idea so I bought a couple of 8x10s last night -- got my Phebe in the mail today -- so I'll head to Harbor Freight or the craft's store tonight and give that glass cutting a go.

I had asked if there was any special instructions I needed to make the Phebe work (considering the page doesn't mention glass or kapton tape or insulation or anything...), Steve wrote "The heated bed is two circuits. Wire 12V DC in parallel. RTV silicon thermistor using temperature RTV. " -- perhaps I asked the question badly. lol

Normally it takes Phebe I about 5-7 minutes to heat up the bed to 125C and it takes about the same to cool to safe temps (I can touch without burning myself).

So... essentially, just let it heat and cool about as fast as it can, on it's own (without outside interference, such as fans, etc...) then?

Yep, that wiki provides basically 100% of what you will need to know about cutting glass. One thing to keep in mind with dollar store glass is that it maybe 2mm or 2.8mm not 3mm, not that it matters, but I have had bad experiences cutting and heating 2mm glass (2.8mm was ok and works as well as 3mm). It just can't handle it, IMO.

As for heating/cooling, basically let it heat and cool on its own and it will be fine. Just remember to be safe with the glass. It wouldn't hurt to heat and cool the bed a few times while standing at a safe distance to make sure nothing gives .

For connecting the Phebe, you have four pads for connecting the bed to power to heat. I connected them in parallel, ran two wires (from the vellman or whatever controls the power for the heated bed) to the first set of + and - pads and then two more from those to the next set. This gives about 3 Ohms resistance with both loops in parallel. The other three pads are for the thermistor, if you are using the thermistor provided by the SeeMeCNC folks, you will just connect two wires (again from the vellman or to whatever controls the heated bed) to the board (pick any of the two pads, doesn't matter) and then connect the thermistor to the similarly marked pads. Place the thermistor in the square area and use RTV to glue in place. That's all!

Yep, that wiki provides basically 100% of what you will need to know about cutting glass. One thing to keep in mind with dollar store glass is that it maybe 2mm or 2.8mm not 3mm, not that it matters, but I have had bad experiences cutting and heating 2mm glass (2.8mm was ok and works as well as 3mm). It just can't handle it, IMO.

As for heating/cooling, basically let it heat and cool on its own and it will be fine. Just remember to be safe with the glass. It wouldn't hurt to heat and cool the bed a few times while standing at a safe distance to make sure nothing gives .

Huh, I'm having a hell of a time cutting it -- getting a little better -- glad I bought two of the suckers...
[img]https://p.twimg.com/A1mZwZ4CMAAuuyk.jpg:large[/img]

... as for the glass itself, my crappy-ass calipers say it's only 1.5 mm thick. Oh joy, it's going to explode on me when I heat it! -- Guess I'll have to buy some good stuff at the hardware shop, after I have some fun exploding this crap!

For connecting the Phebe, you have four pads for connecting the bed to power to heat. I connected them in parallel...

For sure... like, I get all the electronicsy-stuff -- 12 v (in parallel) @ 3 ohms == 4A == ~48 watts of raw manly heating power! -- ...[blah de blah boring details and stuff here]... -- the thing that I have no idea about is stuff like hardware -- the wood -- heat insulation -- that I even needed kapton tape or ABS juice -- none of those fun facts were mentioned anywhere -- question was basically "Is there anything I need to know before I start using this thing?" -- and the answer was what's already silk-screened on the board to begin with! -- If I hadn't discovered these forums I probably would have tried printing directly on the circuit board eventually.

... by the way! Thanks for all your help so far, Michael!

Another dumb question -- when I go to mount the circuit board -- if I use screws/bolts -- the screw/bolt heads create a gap between the top of the Phebe and the glass -- a gap between the Phebe and the glass is bad, right? Should I make the glass smaller than the circuit board so that the screw/bolt heads don't touch it?

Edit: I went back and looked at your pictures for reference -- I see -- it looks like you cut the glass to match the silk-screened white outline on the Phebe. Makes sense.

Ouch! 1.5mm?? That could be a problem! I would be careful with that thin of a glass. You did see correctly, I cut the glass to just the size of the silk screen.

As for why these instructions are not on the Phebe? My only guess is that there are so many and vary so much that it would be impossible to have them on there. We can print directly on the Phebe, but its not the best solution and you can use many forms of tape/coverings to get a better print.

A tip for cutting the glass, make sure that you put a little bit of pressure when scoring the glass. Then over a table edge gently push down on one side of the glass. It will help make the cut clean. But with 1.5mm glass you may not get clean cuts regardless. Also, don't try to cut anything less then 1/2 to 1/4 inch off, I have always had problems cutting that small of an amount off.

Ouch! 1.5mm?? That could be a problem! I would be careful with that thin of a glass. You did see correctly, I cut the glass to just the size of the silk screen.

Yeah, I kept crapping it up, for now I took an aproximately sized shard, and clamped it down with bulldog clamps -- for the long term, I ordered a piece of tempered glass, cut to size, from Elite Custom Glass. I went for a 6" x 7.5" x 3/16" (3/16" = ~ 4.8 mm) clear seamed rectangle. The glass itself was only $20, but shipping was another ~$13.50 -- still that's not too bad, assuming it shows up in one piece.

As for why these instructions are not on the Phebe? My only guess is that there are so many and vary so much that it would be impossible to have them on there. We can print directly on the Phebe, but its not the best solution and you can use many forms of tape/coverings to get a better print.

Yeah, I mean, I'm not saying that they should provide a guide or hold my hand or anything -- but a simple "by the way, you need to insulate this from your plastic print bed, so that your printer doesn't melt (you dumbass)." would've been nice.

Anyway, I soldered, glued, taped, and heat shrinked it up today -- used 16 AWG for each of the four power terminals (had to drill the holes slightly wider for it to fit), and some random (~22 AWG) wire I had laying around for the thermistor.

Also, had to drill the mounting holes slightly wider, so I can mount it to 1/4" plywood (like what you did) but with some #6-32 screws and locknuts. And I cut out a small little notch underneath the solder pads, about 3/16" in from the edge (not shown), so that the wires wouldn't be smashed up against the plywood.

I might also glue down an acrylic sheet (or maybe some lexan) to the old print bed, similar to what you did (not sure what materials you used) -- mostly, I just don't like that the mounting screw holes are so close to the edge of the regular print bed. Anyway, wikipedia says acrylic should be good to 160 °C, and google says Lexan melts at 140 °C, considering there will be wood and an air gap, and those are probably my max temps anyway, I think either should be okay, don't you? Otherwise I might just go with a second piece of wood!

You can see it attached to the wood here, and the closest-to-correct-size shard of glass I could make:
[img]https://p.twimg.com/A1r-V2_CEAEtUU_.jpg:large[/img]

Here's the wiring, glue, and tape, and what not -- decided to go with a red LED to signify "danger":
[img]https://p.twimg.com/A1vv7KxCAAAMqjR.jpg:large[/img]

BrainSlugs83 wrote:I might also glue down an acrylic sheet (or maybe some lexan) to the old print bed, similar to what you did (not sure what materials you used) -- mostly, I just don't like that the mounting screw holes are so close to the edge of the regular print bed. Anyway, wikipedia says acrylic should be good to 160 °C, and google says Lexan melts at 140 °C, considering there will be wood and an air gap, and those are probably my max temps anyway, I think either should be okay, don't you? Otherwise I might just go with a second piece of wood!

I used a piece of Lexan 1/8" thick plastic to glue to the original bed, some PVC primer and glue. The origional bed was just not strong enough to attach the wood/Phebe/glass sandwich. One bit of advice, I did drill the screw holes for the mounting screws to the carriages through the added Lexan glass. That way I could use the same hardware and not have to get longer screws.

An extra piece of wood should also work. It might be a better first option then having to get Lexan glass and glue/primer. Give it a go. If the wood doesn't work, you can always get Lexan and glue, it seems to be holding well for me and the high temps are not bothering it.

BTW, the wiring looks really good! Nice work!

An extra piece of wood should also work. It might be a better first option then having to get Lexan glass and glue/primer. Give it a go. If the wood doesn't work, you can always get Lexan and glue, it seems to be holding well for me and the high temps are not bothering it.

Well, I have Acrylic and Lexan laying around, so I'll give the Lexan a shot then -- adding extra mass to the Y axis seems silly if it can be avoided. And, it looks like I'm treking it back to the hardware store tomorrow anyway... so I'll pick up some PVC primer and glue while I'm there too. Man, they're going to start recognizing me soon! (Which wouldn't be that bad -- the girl at home depot is kinda cute )

BTW, the wiring looks really good! Nice work!

Thanks, man. I'm actually not that proud of it, it looks kinda klunky to me, but I have faith that it will function... Electronics is kind of my thing, sort of, I got on Hack-a-Day earlier this year for soldering a PDIP chip (An ATMega8, from an Arcade Joystick I was building) back together (Right under "You wouldn't download a car", titled "Just be glad it’s not a QFN" on the above Hack-a-Day link. XD):
[img]http://farm8.staticflickr.com/7030/6753 ... e46a_b.jpg[/img]