Posts made by LumberjackEngineering

The machine that has a AC heat bed on it is a Hypercube Evolution. The aluminum toolplate bed itself is grounded, and it's connected to the bed frame via plastic mounts (I.E there is no electrical continuity between the bed and the bed frame). IIRC, I grounded at least one piece of the bed frame, but relying on grounding aluminum extrusion always seem sketchy to me. The layer of anodization (at least the black Misumi extrusion) isn't conductive when tested with at multimeter continuity check voltage levels (3V ish?), so I'm not sure that grounding just one piece is really good enough. I think that they make special screws/washers for grounding extrusion that have teeth on them to dig through the anodization layer.

On the other hand, at higher voltage (I.E if you did have a mains fault) then maybe it's conductive enough that it'd arc to the ground connection through the anodized layer.

Hopefully others can chime in with their experience too!

@claustro That calculator does take into account the bed thickness - which is why it's quite handy! I was more so cautioning others about just using W/cm^2 without any regard to thickness of the bed.

Looks like you've found your answer (and that calculator that @mrehorstdmd linked sure is handy, haven't seen that before!) but I'll add for others that one thing to take into consideration when looking at the power calculations is not just the W/cm^2, but the W/cm^3 as well.

W/cm^2 will give you a good idea of your bed's maximum temperature, but it won't really give you a good idea of how long it's going to take to heat up. I inititally chose roughly 0.35 W/cm^2 for my heat bed, but I went with a 3/8" (~9.5mm) thick aluminum tool plate which meant my heat up times were quite long (10+ minutes for PETG temps). I had based my initial calculations off of a Prusa i3 clone that had a ~3.5mm thick aluminum bed and a heater that provided 0.3 W/cm^2. On that machine, the heat up times were great, so I figured that just matching (or even exceeding a little bit) the W/cm^2 for the Hypercube Evo build that I'd get similar performace. Obviously if I had sat and thought about it for a little bit I would have realized that my heat up times would be roughly 3 times longs, since my bed was roughly three times as thick!

That's why I switched to a 700 watt AC heater mat to give me 0.7 W/cm^2, or 0.073 W/cm^3 (instead of the 0.036 W/cm^3 of the initial DC heater mat). Now I can hit PETG temps in just a couple of minutes!

As others have mentioned though, certainly make sure you do your due diligence if you go the route of an AC heat bed. I used a proper, high quality SSR from a reputable manufacturer, electrical fuses in-line with the machine, and a thermal fused bolted to the aluminum bed itself just in case the SSR fails. The machine is well grounded and the cables are strain relieved. Mains voltage is certainly nothing to play around with, especially when it's a machine that you're not going to be watching all of the time!

I had a wonderful time this year! I'm still not sure what terrible thing I did to my Duet that made it corrupt the SD card a couple hours into Saturday morning, but I had it all back up and running pretty quickly. People passing by were all very impressed with the PanelDue and DWC interfaces, and I had a lot of good conversations with people about how much I love the Duet Wifi/RepRap firmware. I definitely can't wait for next year!

Also, here's a picture of my ridiculous Duet-powered machine at MRRF. To the extent of my knowledge, I'm the first person to put a infinity mirror into a printer (what a claim to fame, hah). So many infinite Z-axis jokes!

With regard to external light, the NIR wavelength this sensor is using will get blocked by essentially anything that blocks visible light.
The reflectivity gets a little bit weirder though - if I remember when I get home, I'll try to do some digging. I can say that black probably isn't going to be the best choice as a lot of black pigments can suddenly turn reflective once you get above visible wavelengths.

There's a few PanelDue 7i cases out there. I myself am partial to this one (https://www.thingiverse.com/thing:2799628), but that's because I designed it heehee. It's not as thin as it could be though, so if that's what you're looking for the one you linked is probably a better fit for you.

It was great to meet everyone! Can't wait for next year.

Whew, just got back from MRRF 2018 - what a great time! Cool to see other Duet's out in the wild and to get to talk to Tony/T3P3. One of the things that I brought up to him in one of the conversations we had is that currently, the Duet doesn't prevent you or throw an error if you try to home the machine before turning the ATX power on.
I realize that the number of people actually using a separate 5V supply is probably pretty slim, so this is probably more of a niche concern. Tony did suggest adding the M80 command + a delay at the beginning of a homing scripts as a method to fix this issue, so I'll give that a shot and see how it goes.

Hey guys,

I've got a TDK-Lamda SWS600L-24 powersupply that I want to control with the Duet Wifi's PS_ON pin (I also have a seperate 5V PSU powering the Duet). In order to achieve this, I think I need to add a pull-up resistor (say, something like 4.7K ohm) between 5V and PS_ON. It seems that when I gave DWC the "ATX Power Off" command the PS_ON pin just floats, which won't work for this particular power supply.

Will this be safe for the Duet? Or do I need to find a 3.3V terminal to attach the pull-up resistor to?

As always, thanks for the help.

Throwing in my $0.02 to say that I'd also buy a sensor that detected that movement was happening, but wasn't necessarily able to quantify exactly how much. Just last night I had a print fail due to a jam (still don't know why…), and would certainly love to be able to detect a situation like that.

Silly question, but why is the red power LED so incredibly bright? I'm running a Duet, so Vin is 3.3V. It's nearly impossible to see the blue trigger LED without covering the always-on power LED!

Alright, got around to snagging some photos. I realized that I really don't have an account on a photo hosting site that's still around, so Instagram will have to do for the moment hah! Click the arrows within the picture to scroll to the different steps. Let me know if something doesn't make sense!

https://www.instagram.com/p/BfMrAR3H8GU/?taken-by=lumberjackengineering

@SputnikOC3d:

Basically I use a pair of small needle nose to pinch the part of the connector that grips the insulation of the wire just enough that it won't fall off. Then I set it on the die of the crimper so that the insulation grabbing part is in the small side and the pin that holds it into the housing is on the outside of the die. Crimp, turn the connector around so that the part that bites into the exposed wire is now on the small side with the holding pin on the outside of the die and crimp again.

interesting - took me a couple reads to sort out your process … what Crimping tool do you have ? I have an IWISS SN-28B. Due to its thickness/width - where the connector goes into the tool - 2 crimps is rather difficult and NOT smashing the whole lot up as trash ... Im suspecting maybe you have a different tool that is not as wide in the crimp holding area

I've got that same crimper - and once you figure out which direction and orientation to insert the Dupont pins/sockets in, it actually makes some solid crimps. I'll snap a couple of pictures of the way I do it when I get home today. It definitely took me a couple dozens of attempts to get it down consistently.

Thanks!

Hi guys!

I'm currently building a Hypercube Evolution, and I've got a Duet Wifi (+ PanelDue 7i) on order from Filastruder. I've got a quick question that I couldn't find a direct answer to from searching the forums, so here it goes:

The HEVO has two carriage-mounted optical endstops, and in my configuration I'm also using a Precision Piezo sensor for bed compensation. Can I share +3.3V and ground connections between these three sensors to help minimize cable clutter? I read a forum post back in December of 2016 where it was stated that you probably shouldn't share the ground used for the thermistor (for temperature accuracy reasons), but is it fine to share the ground and +3.3V power for other (non-fan) things? I don't see why not, but I just wanted to make sure.

Thanks!