What materials for 3D printer enclosure?

[Ranayna]

I am in the process of building an enclosure for my 3D printer. The framework is made from 20mm extruded aluminium profiles, and is already finished.
The bottom and back plate were going to be 18mm coated plywood. I have the cut plates, but have not prepared them further, since currently i am a bit unsure about them.

My next question was: Polycarbonate or Acrylic for the transparent parts?

Acrylic looks nicer and is a bit cheaper, polycarbonate is more robust and can withstand higher temperatures, while being a bit less transparent.
But when comparing these two, i noticed a difference in ignition resistance: Acrylic is classified to be easier to ignite than polycarbonate.
So the answer seems to be obvious, polycarbonate wins out, even if it is a bit more expensive.

But that then got me thinking further: Regarding fire safety, the plywood plates seem to be bad. They offer little protection, and if properly ignited will contribute to a fire.
So should i use them, or should i look for a different material?
I do not really have the facilities to process a metal plate to make cutouts or even drill clean holes, whereas the plywood can be easily drilled. The plywood is also very rigid and heavy, contributing to the stability of the printer.

Finally, a last consideration came up: Are there small smoke detectors that i could integrate into the enclosure, that provide me with an interface to cut power to the printer when smoke is detected?

Maybe i am a bit too concerned? I have reasonable confidence in the safety of the printer, an original Prusa that i assembled myself from the kit, but i am still uncomfortable letting it print unsupervised. Also I will need to modify the cabling if i want to move the powersupply to the outside of the enclosure.

[Lindley]

No, do not think you can be too safe with such devices, though think they are a bit better made than the earlier ones, but do check your model has had any hardware or firmware updates that address such fire risks.

To that end we do not have ours in the main house, but in a work area of the separate garage and we us Octoprint with a  Raps Pi camera to monitor its progress.

We looked around and found that some of the cheap house smoke detectors do have an  output signal point on the pcb  that could be used via the micro to power off the printer and send out and alarm signal to the main house should it start smoking.

We also have it connected to a temperature sensor fitted at the top of the enclosure along with a little display with can view in Octoprint.

When the print ends it pushes the print table fully forwards, but remains powered on, so we used a microswitch to sense that fully forwards position , which after a 5 minute cool down period , cuts all the power off.

As for your enclosure, if metal is not an option for the panels, then can only suggest things like Glass , Plasterboard or Fibre Cement Boards  though both will be very heavy .

[EPAIII]

I have an enclosure in mind and partially designed. Plywood base, 3/4" (19mm), aluminum extrusion frame, and clear plastic sides. Not sure about the top as I want to be able to have one or two reels of filament there.

I had not thought about fire safety. Is there that much of a threat? I have heard of concern about fumes and wanted a vent to outside of the house. My printer is presently in my office. But it would seem easy to add a temperature sensor and/or smoke detector and a single board computer (Arduino, Raspberry Pi, etc.) to monitor them.

Power shut off relay:

https://www.google.com/search?q=power+shutoff+relay&client=firefox-b-1-d&sxsrf=AJOqlzU3PtIStohy_xB6-7NO21yP3Pq6RQ%3A1676958444210&ei=7Fr0Y9e5DO-3qtsPxoSGGA&ved=0ahUKEwjX3_qC9aX9AhXvm2oFHUaCAQMQ4dUDCA8&uact=5&oq=power+shutoff+relay&gs_lcp=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&sclient=gws-wiz-serp

[Ranayna]

So your enclosure will be very similar to mine.
The top of my enclosure will be clear, i decided to make a hinged top door as well, to give me easy access to the printer and the filament, which will be inside the enclosure

I think i will keep with the plywood base for now, at least to finally get the thing finished.
The relay search term helps a lot, i was looking for just such a thing but had no idea what that was called. Now on to find such a thing from a reputable seller.

[Ranayna]

Ok, i think i need to ask another question about these relays.

For example this one:
https://www.ebay.com/itm/DC-24v-Multifunction-Delay-Timing-on-off-Relay-Control-Module-30A-Switch-Timer-/192179077166

While the printer is on, the module is supplied from the printers 24v power supply. A signal on the trigger input can turn the relay off, also powering off the relay module.
So how do i turn the printer on?

The one idea i have would be to use a 220v capable pushbutton in parallel to the relay module. Push and hold until the relay powers up and activates. Then i can release, and the printer stays on.
Manual turning off would be another pushbutton wired to the trigger input, or just throwing the main switch on the powersupply as it is now.

Am i misunderstanding something here? Are there any modules available that auto start and stay on until triggered?
The linked one can only autostart with enabled timer if i understand the listing correctly.

[Lindley]

Ok, i think i need to ask another question about these relays.

For example this one:
https://www.ebay.com/itm/DC-24v-Multifunction-Delay-Timing-on-off-Relay-Control-Module-30A-Switch-Timer-/192179077166

While the printer is on, the module is supplied from the printers 24v power supply. A signal on the trigger input can turn the relay off, also powering off the relay module.
So how do i turn the printer on?

The one idea i have would be to use a 220v capable pushbutton in parallel to the relay module. Push and hold until the relay powers up and activates. Then i can release, and the printer stays on.
Manual turning off would be another pushbutton wired to the trigger input, or just throwing the main switch on the powersupply as it is now.

Am i misunderstanding something here? Are there any modules available that auto start and stay on until triggered?
The linked one can only autostart with enabled timer if i understand the listing correctly.

Cannot see how that particular relay module would work on its own.
Some methods / circuits shown here   -


However we did our own as shown above,which also allows temperature monitoring and the camera etc.
After turning on the wall power socket we have to press the red button to power up the whole system.
Apart from the mains supply, there is no direct connection to any other part of the printers electronics, just a microswitch activated by the bed movement at the end of the print, though no idea if other printers 'eject'  the bed in a similar way to the Ender3.

 

[rdl]

Instead of plywood, go to a home improvement store and look at rigid foam insulation. Other than being not as structurally strong it's better in many ways for projects like this. It's sold in sheets like plywood but weighs very little. It's easy to cut. It has a fairly high service temperature and is more fire resistant. There are several types, so check the specs. I've only used the polyiso kind.

[sokoloff]

Interconnect-capable smoke detectors will put a 9V signal on the interconnect wire to trigger the other detectors to alarm.

You could make use of that signal to cut the power.

[EPAIII]

That relay module does not appear to be suited to use with a 3D printer. It has a pair of contacts for a start/on button, but nothing for a stop/off switch. Interrupting the 24 VDC supply to the board would probably turn things off, but that is not a good way to do so. And it appears to have a timer which, I guess, will shut it down after a delay that is fixed by some solder jumpers on the back of the PCB. I don't think you want that.

A simple relay would be better. I am attaching a concept schematic for a control box that I made for a lathe in my shop. It is simpler as it has no timer. But it does have an stop/off button. This is not the complete schematic, just a concept one from early in the design process. I fear the final schematic might be somewhat confusing.



The ON push button applies 24 V to the relay coil which turns it on. Then the holding contacts on the relay, which are in parallel with that switch, take over and keep the relay coil powered. When the Off button is pressed, it opens that circuit and the relay turns off. This is a very standard and widely used way of activating a relay to control power to a circuit.

While there are relays with 115 or 230 VAC coils and industrial control systems that use them, I do not like controls that use line Voltage. I just don't like having line Voltage in places in a circuit where a lower and therefore safer Voltage will work just as well. So I included a control transformer in that schematic to supply 24 VAC for the relay coil.

And in that final version I also added an overall power switch, power on light, and LED illuminated ON and OFF indicators to show the ON/OFF state of the control. The LED state indicators would be a nice touch for a 3D printer power control. Here is a photo of my complete control.



And one of it's construction in progress:



My apologies but I seem to be having trouble with attachments. I wanted to have them in the text, but they only seem to attach at the bottom.

Ok, i think i need to ask another question about these relays.

For example this one:
https://www.ebay.com/itm/DC-24v-Multifunction-Delay-Timing-on-off-Relay-Control-Module-30A-Switch-Timer-/192179077166

While the printer is on, the module is supplied from the printers 24v power supply. A signal on the trigger input can turn the relay off, also powering off the relay module.
So how do i turn the printer on?

The one idea i have would be to use a 220v capable pushbutton in parallel to the relay module. Push and hold until the relay powers up and activates. Then i can release, and the printer stays on.
Manual turning off would be another pushbutton wired to the trigger input, or just throwing the main switch on the powersupply as it is now.

Am i misunderstanding something here? Are there any modules available that auto start and stay on until triggered?
The linked one can only autostart with enabled timer if i understand the listing correctly.

[EPAIII]

One more point, perhaps too late, I should have added it earlier. You say you can not use metal parts, like side panels. Aluminum can be cut and drilled with the exact same tools as wood. I have cut many aluminum parts with hack saws and my inexpensive (<$99 USD) table saw. Holes can be drilled with standard twist drill bits in a drill press, hand held powered drill, or even an egg-beater style, manually powered drill.

[wilfred]

I've been thinking about making an enclosure too and have the same questions and concerns. I first thought about making a really lightweight one out of big sheets of heavy cardboard covered in aluminium foil and maybe sandwich it with some flat sheets of polystyrene foam use in flat screen TV packaging or  flatpak furniture. The advantage is it will be really lightweight and I can just lift it off easily and the materials are free.  The downside is it is obviously flammable hence the token effort of aluminium foil covering on the inside. It would have been big with fairly large clearance,  hence lightness was a bonus.  I just wanted to stop draughts really and cut down on noise. I am also a bit nervous about leaving it unattended. A smoke detector whether or not it cuts power seems sensible and I do have a fire extinguisher nearby anyway.

Another idea I have toyed with is a skeleton of metal or wood and cover it with a sort of tent made from fire blankets. And still another is to get a discarded washing machine, dryer or similar and gut the contents and use the chassis as the basis of an enclosure. It would need some work making a door but some I've seen are a pretty good fit. Also pretty cheap.

[bonifacio]

I'd say just go for cost. These sheets were expensive last time I check. Started building mine and stopped at the panels.

Acrylic is harder and stronger. But more likely to crack. More scratch resistance.

Polycarbonate is more flexible. Can withstand more of on impact than acrylic.

You could also add a lower powered CPU fan. Add a sensor to maintain an ambient sensor, triggering the fan when it reaches a certain temperature.

For sensors I'd imagine you could just make them yourself or go the easy smart devices route. Grab a smart smoke detector and wall plugs.
Set conditions and automate it. Now that got me thinking, I should do this... Way too simple. How did I not think of this before?



Fire alarm ideas.

https://www.pandapi3d.com/product-page/smoke-alarm-for-3d-printer
https://reprap.org/forum/read.php?339,416260
https://grahamjessup.com/smoke-alarm-shutdown/

[Lindley]

No matter what you build your enclosure of , you most likley still need some form of ventilation to keep the temperature down on long prints ? so any fire could still get out.

Using a smoke alarm, temp sensor with  some device to cut off the mains power to the whole printer would seem to be the best approach , plus you can buy automatic temperature controlled Fire extinguishers.

https://www.fireprotectiononline.co.uk/fire-extinguishers/automatic-fire-extinguishers/