Heated bed

I'm looking to add a heated bed to my delta printer and I've already read the wiki article on them at reprap.org.

I also see lots of red heating elements on Amazon like this one: [www.amazon.com]

But the descriptions are irritatingly vague, leaving me with lots of questions: How big is it? What temperatures can it handle? How do I mount it?

So, does anyone know a reliable source for heated bed parts that can actually fill in some of the questions above? Right now I am looking at a print bed size of about 6"x6", but in a few months I plan on building a new printer with a larger build volume with perhaps a 12"x12" bed.

Edit: Also, what kind of support does it need underneath? If I decide to go with a metal printbed, do I need some other support plate underneath the heater to hold it flat against the bed? Can it also be metal. or should it be nonconductive (if so, then what material)? Does the heater impact the ability to level your bed?

Edited 3 time(s). Last edit at 11/09/2014 05:41PM by mk3a.

The normal size of this is usually 214mm x 214mm

To heat is usually 180 C in my experience

You can put some kind of wood part under it , this is usually done on the regular printers like the Prusa i3

Hope this helps

What do people with larger printers do?

Custom silicon or kapton heaters from china...

Hi,
I have an unusually large printer with a large heated build plate. Some pics on my link below.

In order to make sure the bed remains flat I used 5/16" cast aluminum tooling plate which will not warp when heated like regular aluminum plate. I got this material from a metal supply store as a remnant.

I used 12 aluminum power resistors rated at 50w each, wired in parallel - if any one fails the rest will continue to function.
I got these from China in two lots. One appears to be good quality, the other not nearly so! I recommend getting them from a reputable distributor instead.
I will not use these at over 40W apiece since they are operating at high temperature, and perhaps quite a bit less.

This large heated bed can be heated with just 200W to over 100C, but that takes 30 minutes. I'm building a custom controller and power supply for higher voltage (60v), for faster heatup. About 100C is the right temp for a heated bed for ABS, not 180C.

I attached the resistors to the build plate using blind-tapped holes, and screws with lock washers, and heat sink compound.

The build plate itself is attached securely to the bottom of the printer using stainless all-thread. This doesn't conduct heat well, a good thing. I insulated under the bed (with a 1/4" gap) using R-matte Plus 3 (Home Depot) 1/2 x 4x8 sheet insulation (and also the rest of the chamber). This is a foil covered foam that can take the heat in my build chamber, but perhaps not the max heatbed temp.

After initially roughly calibrating the endstops I only use the tower offsets in Repetier to calibrate for bed leveling. The firmware will do this automatically with a bed leveling sensor.

If you are going to attach a flat heater under the bed using some kind of clamping mechanism, perhaps you could do it with a metal plate - insulated with a layer of fiberglass perhaps so the support would not be heat conducting. I hesitate to recommend clamping a heater on with wood.

Hope your build goes well.

---

My printer: Raptosaur - Large Format Delta - [www.paulwanamaker.wordpress.com]
Can you answer questions about Calibration, Printing issues, Mechanics? Write it up and improve the Wiki!

There is bigger sizes but i believe 214 x 214 is the most popular. I have also been able to print PLA without a heatbed , so like that you can make a huge glass plate to print on

Paul,

Awesome printer. That's a lot like I was imagining I'd like to build. Is there any way I could get specifics on your build?

Thanks


Edit:
For a metal bed, is it better to go with a highly polished surface, or not?

Edited 1 time(s). Last edit at 11/17/2014 12:38AM by mk3a.

Thanks Mk3a,
I don't know that a shiny surface is necessary for a build plate, haven't experience with one. I took some fairly fine sandpaper to mine with a random orbit sander actually. I did that partly because I got some scratch marks on it while machining it, but also I figured it couldn't hurt with things sticking to it. It works fine with glue stick.

I can give you an idea of the dimensions. I will make a full write up on my site after I have finished building... I'm working on the heatbed power supply at the moment. Should be ready to test that soon, as the board is now made.

I used 1 meter Makerslide, so it's a few inches taller than that inside - 43.3 inches.
The entire printer is over 5' tall with the legs. I just upgraded the casters, so I can move it very easily now.

The shape of the top and bottom are a Reuleaux Triangle. This worked perfectly to accommodate the shape of the enlarged bed.

The build plate is over 17" wide across the widest. The largest diameter circle I can print (and get out) is 14", but I can print up to 17" long, and as tall as 24" at the center.

Because of the high heat I used Gorilla Glue (polyurethane) everywhere, it can take the heat unlike most other glues.

All of the cabinet top, bottom, sides, and door was made using 3/4" MDO plywood. This was chosen because of it's stability and nice finish.
The top and bottom use two layers of this, glued and vacuum bagged. These are over 26" across.

The three towers are made using a T shape, with one piece dado'd into the other, and glued with Gorilla Glue and a few screws.
I used Barrel Nuts (From Ebay) to hold the towers very securely to the top and bottom.

The Maker Slide was secured to the towers using eight #10 carriage bolts (1 inch long). These fit well in the back grooves of the track. The center bolts were made fairly secure, but the end ones were looser. The expansion coefficient of plywood is very similar to aluminum - but not exactly the same! I sometimes hear a pop when it is heating or cooling.

The inside is sealed with high temp paint, and then covered in the 1/2" R-matte Plus 3 from (Home Depot) I used a 4x8 sheet, with a bit of Gorilla Glue and 1/4" furniture staples to hold it.

I used Lexan for the double-pane window, as it can take the heat also. I made a nichrome-wire plastic bender for this (which I saw on Youtube).

The segmented / curved sides and door were made using the same plywood, the edges of each segment were beveled on my table saw. I used biscuits and pocket screws (from the inside) to hold them while the glue dried (no clamps required that way). The pocket screws don't show since the inside is all covered with the insulation.

I have to say that I could not have built this except for three things:
- I have quite a bit of woodworking experience.
- I had a good CAD program (Geomagic Design) that allowed me to constrain each moving part, and then grab the effector and move it around. Then I knew how everything would fit. I just had to make it exactly to plan, and everything worked just like the model.
- I have my office at the Vocademy Maker Space. I used their 3'x4' laser cutter to cut templates for every piece. Then I used my router table with a bearing flush-trim bit to finish all the curved pieces to the exact size. Even the build plate. No fiddling!

I still have quite a bit of tweaking to do before I can print the really large models I am planning on.

I also want to lower the mass of some of the moving parts - I can get aluminum bolts to hold the v-bearings and a lighter blower hose. I want to double the magnets in the arms - they stay secure under almost all circumstances, but not under very high accelerations.

I can get 3KG rolls of filament now from Push Plastic, so that will be handy!

Regards
Paul

---

My printer: Raptosaur - Large Format Delta - [www.paulwanamaker.wordpress.com]
Can you answer questions about Calibration, Printing issues, Mechanics? Write it up and improve the Wiki!