heated build chamber

So i want to make a heated build chamber, I just saw this, basically 400w of heater cartridges for 29 bucks is not a bad deal at all. they would be mounted to some over sized pc heatsinks with fans on them to blow hot air into the build chamber.

My question is, could I use 10 of these wired in series and run it off of a solid state relay connected to 120v AC, or perhaps some sort of electronically controlled dimmer switch.

this is the link they are just 40w heater cartridges [gadgets3d.com]

They are for DC?
You will most likely need a diode that will change it to a direct current, but hmm not a good way of doing it.

How about using them in parallel running off a power supply rated for 12 volts with plenty of wattage...

Why not use something like a hairdryer? Seems like it would be very cheap and very high wattage, and it comes built in with a powerful fan...

yeah actually a hot air gun could work pretty well, just have it at the bottom of the build plate blasting hot air into the chamber. thats a good idea.

Have you seen how the "big boys" (all sarcasm intended...) do it? Google Patent is so much better than the USPO site.

[www.google.com]

Here's an excerpt of the patent, emphasis mine...

Quote

The build chamber 24 of the oven 12 is accessible through an insulated oven door 25. As shown in FIG. 2, the build chamber 24 has a floor and right and left sides which are surrounded by a heating duct 26. The heating duct 26 is formed of sheet metal and opens to the build chamber 24 at the top right and top left sides of the chamber 24. A pair of blowers 28 (one shown), located underneath the oven 12 on the right hand side, create a clockwise air flow path through the heating duct 26. Thus, the opening at the top right side of the chamber 24 is an air intake vent 30 and the opening at the top left side of the chamber 24 is an air exhaust vent 32. Two identical banks of six 750 Watt fin-strip heaters 34 are mounted in the heating duct 26 on the air intake side thereof. A venturi 36 is positioned in the heating duct 26 to create a straight flow pattern of air returning to the build chamber 24 through the air exhaust vent 32. The build chamber 24 is heated by convection as air is pulled through the heaters 34, circulated through the duct 26, and returned to the chamber. A sheaf of insulation 37 surrounds the right and left side, the bottom, and a back side of the oven 12 to keep in the heat (insulation 37 is removed in FIG. 1 for purposes of illustration). The build chamber 24 is designed to reach temperatures of at least 200° C. Preferably, a thermocouple and a thermal fuse are placed over the air intake vent 30 so that the temperature in the chamber 24 may be monitored, and, if the chamber 24 becomes too hot, the heaters 34 can be shut off.

Your link goes to a Mendel kit, did you mean this cartridge? [gadgets3d.com]

I'm just starting to test those same ceramic cartridges in my Aluhotend. They do heat but I think the heatgun/hair dryer idea has more legs though you may want to diffuse it a bit. You could wire the cartridges in series and control them with a relay. There are 24vdc units as well which might be better for using that many. And you'd still need fans if you used cartridges. The idea of some sort of temp monitor (K thermocouple?) is a good idea to montior the temps. I use a similar setup from Rocket Scream and Adafruit for a n Arduino controlled reflow oven I'm bulding. You could adapt the relevant part of the control from the reflow oven. It reads the thermocouple and turns a relay off and on to control the heating element. [www.adafruit.com]

It should work, but you should check insulation strength and overall quality, 12V heater cartridge may not be certified to operate with 120V. Operating them at 120V may be life threatening, especially if not galvanically separated from mains.

I took a cheap electric heater and separated the control circuit for the fan and the heater to be separate. The fan got it's own cord so that is could be constantly on to re-circulate the air in the chamber. The heating element remains wired up to the controls and original cord for manual on/off.

Operation is straight-forward. Plug the fan cord into the power-strip so that it's always on for safety. Plug the heater element cord into an outlet that is controlled by an SSR that's hooked up to a PID controller. You need a thermocouple to monitor the temp inside the chamber but that's it.

You may be able to control the chamber with an SSR and RAMPS and avoid the extra expense.

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- akhlut

Just remember - Iterate, Iterate, Iterate!

[myhomelessmind.blogspot.com]

Remember that the heatbed provides a good deal of heat, depending on the size of the chamber.

I have boxed my printer, and without any additional heating I reach approx 35 degrees C, even with a fan running at low speed extracting fumes via a carbon filter in the bottom.

A pic of my setup: [forums.reprap.org]

my build volume is 19^3 so the little dinky heatbed is not going to be enough. the only issue i have with the hot air gun is, they arent meant to run that long, it may be a good way to get the chamber to temperature though.

What is the ideal temp inside the build chamber?

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Waitaki 3D Printer

the idea is that you anneal the platic so it stops warping, I think abs starts melting at 100c, so somewhere below that, stratasys run abs at 80c.

I am totally with Ralf here. My chamber reaches ~45°C although it is rather large. I don't have built-in ventilation, though, and the walls are insulated with aluminium coated styrofoam (originally intended to be installed on the walls behind radiators as additional insulation).
The Mendel layout works quite well, but I think we should move forwards a bit. If we were to implement Ultimaker-style or H-Bot mechanics, a chamber barely larger than the build volume might be possible to build and thus, a heated bed might be sufficient to drive chamber temperatures higher than now. If this isn't sufficient, an additional heater (probably doesn't need much power) might do the trick.

I keep my chamber @50°C for ABS, works quite well
Cheers
Björn

+1 for 45C

I don't have any insulation, but the box is pretty air-tight. It's hot in the summer, but in the winter my office is nice and cozy.

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- akhlut

Just remember - Iterate, Iterate, Iterate!

[myhomelessmind.blogspot.com]

My build cabinet is similar it seems, to UGen's and the temp inside gets to around 38C ( only starting Spring here so cool days). It hasn't made a blind bit of difference yet regarding cracking and warping of taller parts though - obviously more heat needed!

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_______________________________________
Waitaki 3D Printer

I also have my build area only heated by my heat bed.

With a clear garbage bag wrapped around my Prusa I2 I can reach 40C while printing ABS. The advantage of using a clear garbage bag is that I still have a pretty clear view of what is going on inside the chamber while printing.

I think the best way to do this would be to have a box with a hinged door constructed entirely out of 1/8" (~3mm) clear acrylic with all of the gaps sealed with silicone. The clear acrylic would allow you to see what is going on inside the chamber while retaining the heat produced by the heat bed. The door would also allow you to easily remove prints without lifting the box off your printer and thus would retain most of the heat between prints. Unfortunately, my laser cutter is too small to cut out the walls required for this box to fit around my Prusa

Eric

Can confirm that a design with a door or hatch retains a lot of heat...I built my hatch oven-style, which, in hindsight, was not the best idea since when opened, the hatch takes up about half a meter in front of the printer. So side-opening designs might be better for larger chambers.
Sliding doors might be even better since they should not cause as much air turbulence as swinging ones.

By the way, how about printed insulation tiles? I thought about boxes with very sparse infill, preferably multi-chambered (solid layer every x layers in skeinforge) along the heat-gradient so that diffusion doesn't transport the heat that much. Add a layer of IR-reflective material like aluminium foil on one side and you should have a very effective DIY insulator.
The advantage over premade products like styrofoam might be additional features like built-in cable channels and other structures. Maybe this can even be integrated in a box-like printer chassis similar to the Tantillus/Ultimaker.

Edited 1 time(s). Last edit at 09/27/2013 08:40PM by uGen.

In my previous post, I stated that my cabinet didn't see to make much difference. Well, it seems it may have been the black ABS (which can be difficult at the best of times). My orange ABS is significantly better when the cabinet is popped on and that is just with the printer heaters keeping it warm. The cabinet is lined with some kitchen foil so hopefully that's helping. My next move will be to try a tubular 100W halogen lamp inside (and maybe paint the thing!).

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Waitaki 3D Printer

That cabinet looks great!

The only problem with having a wooden cabinet with foil lining is that you can't see through the walls However, you seem to have a viewing window at the front and if you put a lamp inside then visibility should not be a problem. Also, wood has slightly lower thermal conductivity than PMMA so that may positively contribute to heat retention.

Eric

An idea that I have been working on for a while, but have only done some quick checks, is to use a chamber that is open at the top, but use a gas that is is heavier than air even if it is heated - it would only be necessary to form walls and a floor around the heated area. Heat from the build stage would be enough to keep the heavy gas up to a good temperature.

There are many gasses that are heavier than air even when 80 degrees C above the surrounding air, but the heaviest* have some problems so I propose using good old carbon dioxide. As it is not that heavy, there will be some slosh caused by the movement of the platform and/or carriages, but initial trials seem to show that it is not too bad.

I use an extruder with an annular orifice for cooling air around the nozzzle, if ths was supplied from a bottle of dry ice, it could serve the dual function of rapidly cooling the freshly laid filament, while keeping the carbon dioxide topped up.

Mike

* Heavier than air at room temperature include uranium hexafloride, but sadly this is improctical.

p.s., As the heated build chamber is patented and an open enclosure is not a chamber, this would be a work around. If not already patented I believe that this entry in the forum would constitute prior art and stop it being patented

That is a very interesting idea and if the "slosh" caused by the carriage/platform moving through the CO2 gas does not result in too much heat loss then it could be very promising. Have you actually tested this in practice? If so, I would be very interested to hear the detailed results of your experiment

As for the patent issue. I believe the "heated build chamber" is patented by Stratasys, but I do not think an enclosure heated solely by the printer's heat bed violates this patent. I heard that the Stratasys patent covers "actively heated enclosures" so this does not qualify. In fact, before Makerbot merged with Stratasys, they released the Replicator 2X which had a "draft blocking enclosure" which essentially retained the heat produced by the heat bed.

Also, unfortunately I am not sure that your entry on this forum protects this idea from being patented. Supposedly, RepRappers had been talking about an "automated build platform" years before Makerbot implemented it in one of their printers, yet Makerbot still ended up receiving a patent for it

Eric

Edited 1 time(s). Last edit at 09/28/2013 02:54PM by RP Iron Man.

Tests were limited, but I used a glass pot (ca 200mm dia by 200mm tall) from Ikea that I use for acetone vapour polishing on the same Prusa heated build platform that I use for polishing - I did these tests immediately after the acetone had boiled away, so they may be a large ammount of experimental error.

I put two thermocouples in the air about 50mm and 100mm from the bottom and got the tailings of CO2 from a sparklet cartridge. This was enough to give a fairly steady 60C on the lower thermocouple and 50 on the higher one. Stiring with a bunch of pencils to simulate the mechanism on my delta printer caused the temperature to drop about 5 degrees a minute but recovered by 2 degrees after stopping then dropped about 2 degrees a minute without stiring. sinc there was only a little CO2 there I came to the following conclusions

a) Patent it and make vast profits - women, power and all that good stuff.

or

b) It may be a neat idea but needs some work - tell people about it and use any feedback or improvements the
at they come up with when I can get round to it.

Mike

p.s., on patents: you are right, but something in publically accessible records is better than nothing. I understand that somebody was granted a patent for the common wheelbarrow in 1982. I understand that it was an accident, they were trying to patent a new handle for a wheelbarrow, but had they fought for it they had the bit of paper which they could monatarise in one way or another.