Chamber heater plan

oryhara

@zemlin
did you have it running constantly in the chamber?

Maybe i should rethink my plan and use a different heat source...

zemlin

@oryhara - no, I had it on a stand-alone controller. It heated the space nice and quick, but it didn't last long before it smoked. I would STRONGLY discourage you from taking that route - even with a higher quality heat gun.

This is the temperature controller I've used on my heated enclosure projects.
https://www.amazon.com/Inkbird-Temperature-Controller-Fahrenheit-Thermostat/dp/B019I3YCFS
I hook the cooling circuit up to exhaust fans and have it vented to draw outside are when the fans are running.

oryhara

So it seems the heat gun is out. A number of other heat source options have been put forward in this thread. They are as follows.

$65 500W Bolt-Mount Heater from mcmaster who also sells a
$30 500W ceramic lamp heater which are also at amazon as
$16 200W ceramic lamp heaters(suggested to use 2) and I also found
$20 500W PTC heating element, available in many wattages, i just list the 500W for comparison sake

all of these will require a fan to circulate the heat generated, so I'm not factoring that into the comparison.

I'd rather use the maestro to control the heater so it turns on and off with the print than a standalone controller i'd have to manually turn on and off for printing.

And of course all this work is to print ABS(without warping) which I've largely migrated away from in favor of PETG. But I've got a pretty big stockpile of ABS and it would be nice to not have it go to waste. also i like acetone smoothed ABS. its so shiny.

oh and a side note, I just did some quickmafs on my enclosure. It is about 350 liters in volume.

mrehorstdmd

@oryhara My printer's 420 liter volume takes about 20 minutes to heat up to 50C with a 500W chamber heater and 750W bed heater setting the bed to 105C.

You can get a coffee maker for $5 at a second hand store and it pull a 500-1500W heater out of it, with a TCO to guard against excessive temperature rise.

oryhara

@mrehorstdmd what temperature would you recommend getting a TCO at?

I've seen them all the way down to 60C but they were all non-resettable temperature fuses.

I'm not overly concerned with the cost. I was just summing up the various things mentioned. I'm actually leaning towards the most expensive of the listed options because its the one that is intended for this use. "The right tool for the right job" and all that. Or maybe the heat lamp but I'm not sure I can fit that into my enclosure without compromising build volume or gantry travel.

mrehorstdmd

@oryhara Heat lamps use a high temperature filament to radiate heat to whatever they are shining on (like keeping a plate of food warm in a restaurant). I think a convective heater similar to the one I used would be better for the 3D printer application.

I think the TCO temperature you use will depend on how the heater works and how it's installed in your printer. IRIC, the heater I used can get up to about 400C if there's no fan blowing on it, so I think putting a 100C TCO maybe 10 cm directly above the heater will protect against fan failure. It would also protect against SSR failure by allowing the enclosure temp to get up to about 80C and then shut the heater down. I don't think anything in the printer will be damaged by short term exposure to 80C.

The last thing you want is a self resetting TCO that keeps cycling power on and off to an unsafe, uncontrolled heater.

macguyver

From my research the "proper" way would be an enclosure heater from a manufacturer like Stego. They are specifically meant to heat things like electronics enclosures so they should last longer than most cobbled together options. They can also be had second hand on Ebay.

As it happens, I just bought one that should be arriving friday. It's a 250watt 24v option that I am going to try to run off the bed heater circuit since my bed is A/C. We'll see it it gives me that extra little bit I need. They have a lot more powerful options if this doesn't work though. https://www.stego-usa.com/products/heating/

mrehorstdmd

@macguyver Those look pretty good!

macguyver

@mrehorstdmd I like the options, though you have to be careful with them all. There are however the ultra-cheap options I toyed with such as THIS . In the end I eventually stumbled upon the Stego and snagged one up off Ebay for $50. About the same price as anything I would have put together, but much simpler to install and get back to printing in the winter. Though I have a feeling I might need a little more power, like THIS

oryhara

So my new plan is to use the bolt-mount heater and 220V fan like @mrehorstdmd setup. I ordered them yesterday before @macguyver 's post about stego heaters, which I agree would be the 'proper' way to heat my enclosure.

I'm curious now how to place them.
it's a delta, so the bottom is always where the print starts. I know heat rises, so bottom is the best placement.
My question is fan placement. Should it aim at the print, the 0,0,0 coordinate, center of the build area?
or I could point it along the side of the enclosure, basically perpendicular to being aimed at 0,0,0, and hope that the air will circulate around without directly blowing on my part.

Is there conventional wisdom on direct vs indirect hot air blowing on a print? or does the low CFM from using a 220V fan at half its rated voltage mean where it aims is moot?

macguyver

@oryhara I think blowing across the part would be counter productive. The air is still going to be colder than the part so I would think it would still cool it down faster and risk warping/cracking.

You may need a more powerful fan depending on how low the CFM is on what you have. My enclosure is almost air tight. The heatbed heats the air ABOVE the heatbed 20+ degrees over ambient, but does next to nothing for the air below it. With the heater above you may only heat the enclosure as far down as the fan can push it down, before it starts rising. You may want to do some tests moving a thermistor to various spots in the enclosure to see if it heats evenly.

theruttmeister

@oryhara said in Chamber heater plan:

Is there conventional wisdom on direct vs indirect hot air blowing on a print? or does the low CFM from using a 220V fan at half its rated voltage mean where it aims is moot?

As @macguyver says, moving air will cool the part faster than stationary air (and its a proportional relationship, move the air twice as fast, cool twice as much).

Given the large vertical dead space in a delta your concern seems reasonable though. The goal is to keep the polymer at or close to its glass transition temp.
Your choices are probably:

Pure convection, but run hotter, so the dead space is actually hotter than you want, but the build volume is at the target temp. (With the risk that the top of the space could get really really hot.
Fan. But run hotter so that the air is at or close to the target temp of the polymer. The fan should give you a more uniform temp, and you might not need to run that much hotter.

Direct is going to be more of a problem, as it will require the highest temp, and unless it heats up the whole enclosure doesn't really solve the problem (non-uniform rate of cooling).

And as others have said (and I have built and tested) IR heaters are not the right solution. The primary heat loss from the part is convection, so you need to heat the air.
You can use IR, but it takes a lot more power!

oryhara

I've got the heater and fan mounted in my enclosure. The effector just misses the brackets there at the edge of its travel.

Now I just need to wire them up.

A Former User

@oryhara said in Chamber heater plan:

I've got the heater and fan mounted in my enclosure. The effector just misses the brackets there at the edge of its travel.

Now I just need to wire them up.

Ever heard of a file ?

mrehorstdmd

@oryhara I can't figure out what I'm looking at. What kind of fan/duct is that? It looks like the heater is very close to the side wall (if that's clear PC sheet there).

oryhara

@CaLviNx
I'll make it pretty after i make it work. if it don't work it doesn't matter how pretty it looks.

@mrehorstdmd It's not that close. about 50 or 60 mm away. The picture isn't at the best angle. and the fan duct is just to try and keep the fan from blowing right on the part.

Update: I've got it wired up. now trying to get the heater tuned. The problem is the temp rise is so slow that m303 fails to detect any rise at all. I set the dead time to 60 seconds but i think i need to change the gain so the m303 will work.

A Former User

@oryhara said in Chamber heater plan:

@CaLviNx
I'll make it pretty after i make it work. if it don't work it doesn't matter how pretty it looks.

@mrehorstdmd It's not that close. about 50 or 60 mm away. The picture isn't at the best angle. and the fan duct is just to try and keep the fan from blowing right on the part.

Update: I've got it wired up. now trying to get the heater tuned. The problem is the temp rise is so slow that m303 fails to detect any rise at all. I set the dead time to 60 seconds but i think i need to change the gain so the m303 will work.

The old saying goes: if it looks right, it usually is right.

Pride in your work and doing the best you can even for prototyping is just good practice.

oryhara

@CaLviNx form follows function

like i said I'll make it pretty when it works.
which it doesn't at the moment. I can't get M303 to run because it heats so slowly, even with the bed at 100 degrees.

@mrehorstdmd I'm curious how you got your chamber heater model to work, given you said it takes 20 minutes to get to 50C

oryhara

still no joy with M303 but with a gain set nice and low M141 seems to be working ok. I set the model parameters manually per the instructions:
https://duet3d.dozuki.com/Wiki/Tuning_the_heater_temperature_control#Section_Setting_the_model_parameters_manually

so now I get to make it pretty.
@CaLviNx you said something about a file? what needs filing?
you want I should round off the corners of the mounting bracket?

mrehorstdmd

@oryhara I'm pretty sure I've got the chamber heater running in bang-bang mode. I'll check the config file when I get home.