Heatbed Heater Options I'm in the process of doing some much needed upgrades to my printer's heatbed, and I'm trying to workout my best option. The existing heated bed was done with 4 x 4.7R power resistors (aluclad type) and the temperature maxed out around 70C. I have just mounted 4 x 2.2R power resistors, but I haven't tested them yet. They're 8W as opposed to the 15W ones that were there, and although they have a max temp rating of 300C, I'm a little apprehensive about them, and the wire that connects them. It's really thick, but by my calculations, there's going to be something like 21A through the wire, and I'm not sure if it (or my RUMBA board) will take that. The power supply DEFINITELY will, as it's rated for 58A at 12V. Pics of the current bed and wires (I put in a normal single core wire beside it for comparison): [img]http://i58.tinypic.com/1192ly1.jpg[/img] [img]http://i57.tinypic.com/6qwlqv.jpg[/img] Anyway, this all has me considering some other heater solutions, but there's a few issues involved, and I'm trying to do this as cheap as possible really. So, PCB. I'd be looking at a 300x300mm one, but because of the existing gantry, the corner mounting holes wont work. The one in the middle is fine, but I'd need to drill new holes in a PCB heat bed, and I don't know if i can do that. I have a vague recollection of some site saying it was fine provided it was outside the white outline of the text/border on the top surface of the heatbed. Confirmation of this would be great The other two options are Polyimide or a silicon heater mat. With the polyimide, same principle of having to drill it applies. The silicone mat, same thing. I think i'd prefer the PCB option so i can keep the weight down, but I'm a bit stuck on this one. As you can see on the image of the bed, the mounting holes are the problem with the options, but it would be less so if I could drill a PCB heater. Anyone able to shed some light on the situation? https://reprap.org/forum/read.php?13,437051,437051#msg-437051 Sun, 08 Mar 2026 20:31:31 -0400 Phorum 5.2.23 https://reprap.org/forum/read.php?13,437051,459452#msg-459452 Re: Heatbed Heater Options https://reprap.org/forum/read.php?13,437051,459452#msg-459452


I'm still not sure about the wires coming from the heatbed. Should I replace them with something thicker?
]]> twicx Controllers Fri, 23 Jan 2015 07:17:15 -0500 https://reprap.org/forum/read.php?13,437051,457216#msg-457216 Re: Heatbed Heater Options https://reprap.org/forum/read.php?13,437051,457216#msg-457216


So that means I'm going to need resistors across Ground and 1 x Red Wire (+5V), 1 x Orange Wire (+3.3V) and 1 x Purple Wire (5V StandBy), so that they reach minimum loads, am I correct?

If so, then by my calculations, these power resistors should do it:
27R @ 1W across the 3.3V (122mA)
47R @ 1W across the 5V (106mA)
47R @ 1W across the 5V (106mA)

1W resistors I should be able to get this week easily and cheaply, but before I do, I just thought I'd check to make sure that I'm correct in my calculations!
]]> twicx Controllers Sun, 18 Jan 2015 19:15:51 -0500 https://reprap.org/forum/read.php?13,437051,457014#msg-457014 Re: Heatbed Heater Options https://reprap.org/forum/read.php?13,437051,457014#msg-457014
The fans I have are 0.96W, and I don't have any power resistors remotely large enough. According to this site (http://makezine.com/projects/computer-power-supply-to-bench-power-supply-adapter/), a 10R resistor at 10W across the +5V and Ground is enough for most PSUs. But it looks like I can also test it with the fan in there first to see if it does generate enough of a load. If it shuts off, at least I wont be damaging the PSU, right??

The next thing I've just noticed is that the wires coming off the new heatbed are quite thin. I measured the resistance, and it's a solid 1.5R, so by my calculations, that's 8A. Based on my earlier diagram of using the SSR, I'm wondering if those thin wires from the head bed will be thick enough to take 8A. This is them compared to some of the ones I've trimmed from the PSU:


The black/yellow are the PCB, the purple/grey were cut from the PSU.
]]> twicx Controllers Sun, 18 Jan 2015 10:31:02 -0500 https://reprap.org/forum/read.php?13,437051,457005#msg-457005 Re: Heatbed Heater Options https://reprap.org/forum/read.php?13,437051,457005#msg-457005
One easy solution would be to connect a 12V rear light auto bulb across the 12V supply (AFAIR these bulbs are about 5W), and another across the 5V output.]]> dc42 Controllers Sun, 18 Jan 2015 10:16:16 -0500 https://reprap.org/forum/read.php?13,437051,456977#msg-456977 Re: Heatbed Heater Options https://reprap.org/forum/read.php?13,437051,456977#msg-456977
]]> twicx Controllers Sun, 18 Jan 2015 08:57:53 -0500 https://reprap.org/forum/read.php?13,437051,456936#msg-456936 Re: Heatbed Heater Options https://reprap.org/forum/read.php?13,437051,456936#msg-456936
I'm now making a start on the long journey to doing all the upgrades. The first thing to tackle is the ATX power supply. I'm making a start now on tidying up all the wiring, removing excess wires etc. I know there is a chance that I'm going to have to put a load across the +5V, so I've a few questions with wiring this up:

1. IF I test it and I find that I do need a load resistor, could I use a 12V DC fan? I know that at 5V, it wont be running at full power, but it's ok, I'll find a use for it. If not, I've a tonne of 0.25W resistors. Would they suffice, and if so, what value should I be looking at?

2. I'm going to have to use my old heatbed to print a bunch of new parts for mounting the new heatbed. Thing is, it's currently mounted with 4 x 2R2 8W aluminium clad power resistors. The datasheet for them is here: http://uk.farnell.com/te-connectivity-cgs/ths152r2j/resistor-al-clad-15w-2r2-5/dp/1259346 I can't seem to find a Maximum Temperature for them. Originally, the heatbed had 4 x 4R7 15W aluminium clad power resistors, and I still have those somewhere. I'm trying to establish if I can get away with the 2R2 resistors for a short while to get the parts printed. I know they only heat in spots, but it's only a very temporary solution.]]> twicx Controllers Sun, 18 Jan 2015 07:29:36 -0500 https://reprap.org/forum/read.php?13,437051,448001#msg-448001 Re: Heatbed Heater Options https://reprap.org/forum/read.php?13,437051,448001#msg-448001 twicx Controllers Sat, 27 Dec 2014 09:54:04 -0500 https://reprap.org/forum/read.php?13,437051,447933#msg-447933 Re: Heatbed Heater Options https://reprap.org/forum/read.php?13,437051,447933#msg-447933
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twicx
So this looks like a good option, right?
ebay ssr

Yes, and the supplied heatsink will likely be adequate at 15A. Mount the heatsink with the fins vertically so that convection draws air over them, or else use a fan to blow air between the fins. The datasheet will tell you the maximum surface temperature of the SSR permitted as a function of current.]]> dc42 Controllers Sat, 27 Dec 2014 03:44:28 -0500 https://reprap.org/forum/read.php?13,437051,447886#msg-447886 Re: Heatbed Heater Options https://reprap.org/forum/read.php?13,437051,447886#msg-447886 ebay ssr]]> twicx Controllers Fri, 26 Dec 2014 20:12:43 -0500 https://reprap.org/forum/read.php?13,437051,447298#msg-447298 Re: Heatbed Heater Options https://reprap.org/forum/read.php?13,437051,447298#msg-447298
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dc42
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dougal1957
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dc42
The 100 degC or so that you need on the hot bed for printing ABS is too hot for cooling the SSR.

Thought that may be the case If I was to use one it would go under my Bottom plate underneath the printer along with the rest of the Electronics PSU's and motors but as my heatpad is a 400mm x 400mm 230V AC Silicon heater it shouldn't be anywhere near the same issues (I will be using a SSR to switch it). It has an inbuilt thermocouple that I would like to use just not sure how to yet more research is needed I think! ;)

The current drawn by your mains-voltage heatbed should be very low (I am guessing 1 to 2A), so the heat generated by your SSR will be much lower than the heat generated by twicx's DC SSR carrying 15A. You can use an inexpensive zero-crossing AC SSR.

Yep that's what I reckoned as well the heater will be under a piece of Ally that by the time it is all put together will be 9mm thick (Weigh's a ton but as it will only be moving in the vertical plane it should be fine) top plate is 6mm ECOCAST machined flat and that is mounted to a larger piece of 3mm sheet for mounting/levelling purposes (Top is 400x400 lower piece 450x450 mm) this will all be on a CoreXY Machine using NEMA23's for all motion motors and 17's on the extruder's E3D Kraken hotend.

Will start a new thread re the Thermocouple and see what other's say about it.]]> dougal1957 Controllers Wed, 24 Dec 2014 09:20:11 -0500 https://reprap.org/forum/read.php?13,437051,447286#msg-447286 Re: Heatbed Heater Options https://reprap.org/forum/read.php?13,437051,447286#msg-447286
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dougal1957
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dc42
The 100 degC or so that you need on the hot bed for printing ABS is too hot for cooling the SSR.

Thought that may be the case If I was to use one it would go under my Bottom plate underneath the printer along with the rest of the Electronics PSU's and motors but as my heatpad is a 400mm x 400mm 230V AC Silicon heater it shouldn't be anywhere near the same issues (I will be using a SSR to switch it). It has an inbuilt thermocouple that I would like to use just not sure how to yet more research is needed I think! ;)

The current drawn by your mains-voltage heatbed should be very low (I am guessing 1 to 2A), so the heat generated by your SSR will be much lower than the heat generated by twicx's DC SSR carrying 15A. You can use an inexpensive zero-crossing AC SSR.]]> dc42 Controllers Wed, 24 Dec 2014 08:37:06 -0500 https://reprap.org/forum/read.php?13,437051,447246#msg-447246 Re: Heatbed Heater Options https://reprap.org/forum/read.php?13,437051,447246#msg-447246
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dc42
The 100 degC or so that you need on the hot bed for printing ABS is too hot for cooling the SSR.

I am tempted to design a heat bed switch that has a much lower voltage drop than an SSR but still provides isolation. But I suspect that the demand would be too low to make it worth my while having some built.

Thought that may be the case If I was to use one it would go under my Bottom plate underneath the printer along with the rest of the Electronics PSU's and motors but as my heatpad is a 400mm x 400mm 230V AC Silicon heater it shouldn't be anywhere near the same issues (I will be using a SSR to switch it). It has an inbuilt thermocouple that I would like to use just not sure how to yet more research is needed I think! ;)]]> dougal1957 Controllers Wed, 24 Dec 2014 06:20:42 -0500 https://reprap.org/forum/read.php?13,437051,447187#msg-447187 Re: Heatbed Heater Options https://reprap.org/forum/read.php?13,437051,447187#msg-447187
I am tempted to design a heat bed switch that has a much lower voltage drop than an SSR but still provides isolation. But I suspect that the demand would be too low to make it worth my while having some built.]]> dc42 Controllers Wed, 24 Dec 2014 03:00:20 -0500 https://reprap.org/forum/read.php?13,437051,447177#msg-447177 Re: Heatbed Heater Options https://reprap.org/forum/read.php?13,437051,447177#msg-447177
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dc42
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dougal1957
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twicx
That's a damn sight cheaper. I might go for that, or, at the very least, use it as a reference for finding what i need.

Thanks again!

I quoted this earlier in the thread and DC42 did say that they have a high Voltsdrop across them so you may have to increase your supply Volts to it or use a slightly lower resistance on your bed to compensate for it (I am no expert on SSR's and I plan on using a AC Fed silicon heater on my large build).

Doug

Yes it does quote a relatively high voltage drop on the datasheet (1V maximum), but so does the 40A one from RS. Either of them is likely to need a heatsink to carry 15A.

yeah think so could always mount it on the Alloy bed to help with heating it though not sure if that kind of heat would affect it operation at all?]]> dougal1957 Controllers Wed, 24 Dec 2014 01:35:48 -0500 https://reprap.org/forum/read.php?13,437051,447128#msg-447128 Re: Heatbed Heater Options https://reprap.org/forum/read.php?13,437051,447128#msg-447128
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dougal1957
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twicx
That's a damn sight cheaper. I might go for that, or, at the very least, use it as a reference for finding what i need.

Thanks again!

I quoted this earlier in the thread and DC42 did say that they have a high Voltsdrop across them so you may have to increase your supply Volts to it or use a slightly lower resistance on your bed to compensate for it (I am no expert on SSR's and I plan on using a AC Fed silicon heater on my large build).

Doug

Yes it does quote a relatively high voltage drop on the datasheet (1V maximum), but so does the 40A one from RS. Either of them is likely to need a heatsink to carry 15A.]]> dc42 Controllers Tue, 23 Dec 2014 18:16:50 -0500 https://reprap.org/forum/read.php?13,437051,447020#msg-447020 Re: Heatbed Heater Options https://reprap.org/forum/read.php?13,437051,447020#msg-447020
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twicx
That's a damn sight cheaper. I might go for that, or, at the very least, use it as a reference for finding what i need.

Thanks again!

I quoted this earlier in the thread and DC42 did say that they have a high Voltsdrop across them so you may have to increase your supply Volts to it or use a slightly lower resistance on your bed to compensate for it (I am no expert on SSR's and I plan on using a AC Fed silicon heater on my large build).

Doug]]> dougal1957 Controllers Tue, 23 Dec 2014 13:21:35 -0500 https://reprap.org/forum/read.php?13,437051,447017#msg-447017 Re: Heatbed Heater Options https://reprap.org/forum/read.php?13,437051,447017#msg-447017
Thanks again!]]> twicx Controllers Tue, 23 Dec 2014 13:18:11 -0500 https://reprap.org/forum/read.php?13,437051,447016#msg-447016 Re: Heatbed Heater Options https://reprap.org/forum/read.php?13,437051,447016#msg-447016
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twicx
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dc42
No, not for the heated bed/relay section. But you will probably need a load on the 5V output from the ATX supply to keep it happy. If you will be using an LCD display, the backlight of that display may be enough load for the 5V output, and by connecting the backlight there instead of to the Rumba 5V output, you will keep the 5V regulator on the Rumba cooler.

Ok grand. My instinct is to run one of the always-on fans off this, as I'm not using an LCD display, or maybe something like an LED. Something simple.

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dc42
Zero-crossing and random-fire only refer to SSRs used for switching AC loads. You cannot use an AC SSR to switch DC. This rules out most SSRs. In the parametric selector on the RS Solid State Relay page, under "Output device" deselect "triac" and "paired SCR". Of the ones left, this one [uk.rs-online.com] is the cheapest I found that can handle 20A. Check the datasheet for heat sinking requirements - the 20A rating is with a heatsink. You may be better off using an SSR rated at e.g. 40A, because at 20A it will need little or no heatsinking.

Ah ok, well at least now I'm clear on what I'm looking for. I would be inclined to pay that bit more for the 40A one to avoid the heatsink. I think the heatbed is going to end up with a current draw of something between 10 and 15A, but i'll have to wait till it arrives to measure it exactly. At least now it's a bit clearer.

Thanks again for the help. Its top of my to-do list after my exams on the 6th.

try something like this 40A DC-DC SSR]]> dougal1957 Controllers Tue, 23 Dec 2014 13:16:32 -0500 https://reprap.org/forum/read.php?13,437051,447001#msg-447001 Re: Heatbed Heater Options https://reprap.org/forum/read.php?13,437051,447001#msg-447001
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dc42
No, not for the heated bed/relay section. But you will probably need a load on the 5V output from the ATX supply to keep it happy. If you will be using an LCD display, the backlight of that display may be enough load for the 5V output, and by connecting the backlight there instead of to the Rumba 5V output, you will keep the 5V regulator on the Rumba cooler.

Ok grand. My instinct is to run one of the always-on fans off this, as I'm not using an LCD display, or maybe something like an LED. Something simple.

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dc42
Zero-crossing and random-fire only refer to SSRs used for switching AC loads. You cannot use an AC SSR to switch DC. This rules out most SSRs. In the parametric selector on the RS Solid State Relay page, under "Output device" deselect "triac" and "paired SCR". Of the ones left, this one [uk.rs-online.com] is the cheapest I found that can handle 20A. Check the datasheet for heat sinking requirements - the 20A rating is with a heatsink. You may be better off using an SSR rated at e.g. 40A, because at 20A it will need little or no heatsinking.

Ah ok, well at least now I'm clear on what I'm looking for. I would be inclined to pay that bit more for the 40A one to avoid the heatsink. I think the heatbed is going to end up with a current draw of something between 10 and 15A, but i'll have to wait till it arrives to measure it exactly. At least now it's a bit clearer.

Thanks again for the help. Its top of my to-do list after my exams on the 6th.]]> twicx Controllers Tue, 23 Dec 2014 12:36:34 -0500 https://reprap.org/forum/read.php?13,437051,446995#msg-446995 Re: Heatbed Heater Options https://reprap.org/forum/read.php?13,437051,446995#msg-446995
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twicx
1. On the RUMBA board, there's 2 terminals for HB-PWR, which normally connects to the PSU. They're right beside the HB-OUT. If I'm using a SSR Relay, what do these connect to?

To +12V and 12V ground as usual. You can link them across to the other 12V terminals - no need to run separate 12V power to them in this case.

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twicx
2. This was one of the diagrams I was looking at for working this out: RELAY CONFIG
The pinouts are a little confusing, as far as +/- on the board, +/- on the heat bed, and +/- on the relay. I would have thought that the +/- have to all line up. I know this sounds like a realy electrical noob question, but it's essentially just a loop from +12V on the ATX to the GND on the ATX (like in my diagram?) Is this correct?

The Load- terminal on the SSR connects to the + terminal on the heated bed, but otherwise the + and - should all line up.

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twicx
3. I've seen a few diagrams with things like lamps and resistors and diodes across things, and others without them. I know it was mentioned earlier that I will need to test my new PSU to see if it needs a load at the 5V to power on, and if so, there's a few options like a fan or a resistor, but I'm specifically talking about the head bed/relay section. Do I need all these extra diodes and lamps?

No, not for the heated bed/relay section. But you will probably need a load on the 5V output from the ATX supply to keep it happy. If you will be using an LCD display, the backlight of that display may be enough load for the 5V output, and by connecting the backlight there instead of to the Rumba 5V output, you will keep the 5V regulator on the Rumba cooler.

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twicx
4. As far as the relay itself goes, my preference is to order something from this site: http://ie.rs-online.com/web/
I'm going to be ordering some stuff from them in the new year for a completely un-related project (Guitar amps) and it would save me on shipping. The only problem is, they have about 2000 different SSRs, and I have no idea what the exact one I'm looking for. They have things like zero-cross over things and I'm a bit lost. What would be the most exact description of it?

Zero-crossing and random-fire only refer to SSRs used for switching AC loads. You cannot use an AC SSR to switch DC. This rules out most SSRs. In the parametric selector on the RS Solid State Relay page, under "Output device" deselect "triac" and "paired SCR". Of the ones left, this one [uk.rs-online.com] is the cheapest I found that can handle 20A. Check the datasheet for heat sinking requirements - the 20A rating is with a heatsink. You may be better off using an SSR rated at e.g. 40A, because at 20A it will need little or no heatsinking.

Unfortunately, DC SSRs are expensive. If the Rumba board made the HB drive signal available externally, then I would suggest using two SevenSwitch boards in parallel instead - but from what I can see, the Rumba doesn't provide that signal externally.]]> dc42 Controllers Tue, 23 Dec 2014 12:26:40 -0500 https://reprap.org/forum/read.php?13,437051,446964#msg-446964 Re: Heatbed Heater Options https://reprap.org/forum/read.php?13,437051,446964#msg-446964
From looking at this again, I think a solid state relay seems to be the easiest solution, but as there's always a risk of damaging something, I'm doing all the research I can. First and foremost, from looking around, it seems like my wiring diagram will be this:



There's a few questions I have on it though.
1. On the RUMBA board, there's 2 terminals for HB-PWR, which normally connects to the PSU. They're right beside the HB-OUT. If I'm using a SSR Relay, what do these connect to?

2. This was one of the diagrams I was looking at for working this out: RELAY CONFIG
The pinouts are a little confusing, as far as +/- on the board, +/- on the heat bed, and +/- on the relay. I would have thought that the +/- have to all line up. I know this sounds like a realy electrical noob question, but it's essentially just a loop from +12V on the ATX to the GND on the ATX (like in my diagram?) Is this correct?

3. I've seen a few diagrams with things like lamps and resistors and diodes across things, and others without them. I know it was mentioned earlier that I will need to test my new PSU to see if it needs a load at the 5V to power on, and if so, there's a few options like a fan or a resistor, but I'm specifically talking about the head bed/relay section. Do I need all these extra diodes and lamps?

4. As far as the relay itself goes, my preference is to order something from this site: http://ie.rs-online.com/web/
I'm going to be ordering some stuff from them in the new year for a completely un-related project (Guitar amps) and it would save me on shipping. The only problem is, they have about 2000 different SSRs, and I have no idea what the exact one I'm looking for. They have things like zero-cross over things and I'm a bit lost. What would be the most exact description of it?

Again, MASSIVE thanks for the help on this.
]]> twicx Controllers Tue, 23 Dec 2014 10:33:27 -0500 https://reprap.org/forum/read.php?13,437051,438521#msg-438521 Re: Heatbed Heater Options https://reprap.org/forum/read.php?13,437051,438521#msg-438521 twicx Controllers Mon, 01 Dec 2014 05:25:46 -0500 https://reprap.org/forum/read.php?13,437051,438114#msg-438114 Re: Heatbed Heater Options https://reprap.org/forum/read.php?13,437051,438114#msg-438114 dc42 Controllers Sat, 29 Nov 2014 13:04:12 -0500 https://reprap.org/forum/read.php?13,437051,437996#msg-437996 Re: Heatbed Heater Options https://reprap.org/forum/read.php?13,437051,437996#msg-437996
As far as the MOSFETs in parallel, I had a read through the SevenSwitch research pages, and had a little look at a few other sites and I'm just wondering if there's any reason why I couldn't just use a different MOSFET to handle the higher current? For example, IRF3708 is good for 62A Digikey]]> twicx Controllers Sat, 29 Nov 2014 07:17:14 -0500 https://reprap.org/forum/read.php?13,437051,437950#msg-437950 Re: Heatbed Heater Options https://reprap.org/forum/read.php?13,437051,437950#msg-437950 reprap.org] and follow the link to github for the schematic.]]> dc42 Controllers Sat, 29 Nov 2014 03:59:02 -0500 https://reprap.org/forum/read.php?13,437051,437890#msg-437890 Re: Heatbed Heater Options https://reprap.org/forum/read.php?13,437051,437890#msg-437890 twicx Controllers Fri, 28 Nov 2014 19:13:27 -0500 https://reprap.org/forum/read.php?13,437051,437401#msg-437401 Re: Heatbed Heater Options https://reprap.org/forum/read.php?13,437051,437401#msg-437401
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dc42
Although those Fotek DC-DC SSRs are easy to wire up, unfortunately they have quite a high maximum voltage drop (1.6V, see [www.fotek.com.hk]) and hence there will be a lot of heat to get rid off. You would be better off using 2 mosfets (chosen for very low Rds(on) @ 4.5V gate voltage) wired in parallel.

I still don't get how I would connect these up, or what kind of mosfets to go for.

But that aside, does that mean I could go for a big PCB board (assuming I solve the mounting issue) and just use the two mosfets between the board and the heater?]]> twicx Controllers Thu, 27 Nov 2014 11:09:16 -0500 https://reprap.org/forum/read.php?13,437051,437398#msg-437398 Re: Heatbed Heater Options https://reprap.org/forum/read.php?13,437051,437398#msg-437398 www.fotek.com.hk]) and hence there will be a lot of heat to get rid off. You would be better off using 2 mosfets (chosen for very low Rds(on) @ 4.5V gate voltage) wired in parallel.]]> dc42 Controllers Thu, 27 Nov 2014 11:03:48 -0500 https://reprap.org/forum/read.php?13,437051,437312#msg-437312 Re: Heatbed Heater Options https://reprap.org/forum/read.php?13,437051,437312#msg-437312
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dougal1957
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twicx
So by the sounds of it, I'm going to need something between the Rumba, the power supply and the heater(s). This makes it tricky.

The first problem is the mounting points. Because of the design of how the bed is mounted to the z axis gantry, the mounting points for anything is going to be a tricky issue. My printer (Felix 1.5 Rev.E) uses 3 mounting points for the Heated bed. One is in the centre of the heated bed, and the other two are in the corners. However, if I move to a larger print bed, for example, 300mm x 300mm, Those two corner mounting points move up along the edge by about 1/3. So the centre mounting point would be the same, but the two other corner ones would still be on the edges, but about 40-60mm from the corner. Looking at the PCB option, I think I made an error in thinking that the holes in the middle of them are another mounting point. I think they're for the thermistor.

The next problem is the power supply. I've already gotten a new ATX power supply that puts out 58A at 12V, so I would like to try to stick with that one, rather than go to 24V.

This brings me back to the whole heater issue. By the sounds of it, I need something to manage the power (it's going to be >10A) in or around the Rumba/Heater/Powersupply. What would be my cheapest/best/easiest solution for that?

As for the heaters, I still like the convenience of the PCB one in that I can keep the weight of the heat bed down. It looks like I can drill outside of the white boundary line where the traces are, but then I still have the problem of that 3rd mounting point in the centre of the board, which I'm not so sure how to tackle. I'm still very reluctant to use the silicone ones, and I'd favor the kapton foil option over those, as they're cheaper, adhesive, and maybe 4 x foil heaters might be an option.

Edit:
[www.alibaba.com]

This is the kind of printbed I have in mind. The ideal (albeit optimistic) setup would be that, use the center hole as the 3rd mount point, drill two new mount points up from the corners (you can also see the white border), and then figure out how to manage the power supply bit. Is this possible?

Try looking at a Solid State Relay these can be driven by your Rumba board easily and still switch the high current dc that you need They are available in various Current rating's

Doug

Forgive my ignorance, but how are they connected up? is there somewhere that has a good guide on them?]]> twicx Controllers Thu, 27 Nov 2014 07:25:24 -0500 https://reprap.org/forum/read.php?13,437051,437311#msg-437311 Re: Heatbed Heater Options https://reprap.org/forum/read.php?13,437051,437311#msg-437311
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twicx
So by the sounds of it, I'm going to need something between the Rumba, the power supply and the heater(s). This makes it tricky.

The first problem is the mounting points. Because of the design of how the bed is mounted to the z axis gantry, the mounting points for anything is going to be a tricky issue. My printer (Felix 1.5 Rev.E) uses 3 mounting points for the Heated bed. One is in the centre of the heated bed, and the other two are in the corners. However, if I move to a larger print bed, for example, 300mm x 300mm, Those two corner mounting points move up along the edge by about 1/3. So the centre mounting point would be the same, but the two other corner ones would still be on the edges, but about 40-60mm from the corner. Looking at the PCB option, I think I made an error in thinking that the holes in the middle of them are another mounting point. I think they're for the thermistor.

The next problem is the power supply. I've already gotten a new ATX power supply that puts out 58A at 12V, so I would like to try to stick with that one, rather than go to 24V.

This brings me back to the whole heater issue. By the sounds of it, I need something to manage the power (it's going to be >10A) in or around the Rumba/Heater/Powersupply. What would be my cheapest/best/easiest solution for that?

As for the heaters, I still like the convenience of the PCB one in that I can keep the weight of the heat bed down. It looks like I can drill outside of the white boundary line where the traces are, but then I still have the problem of that 3rd mounting point in the centre of the board, which I'm not so sure how to tackle. I'm still very reluctant to use the silicone ones, and I'd favor the kapton foil option over those, as they're cheaper, adhesive, and maybe 4 x foil heaters might be an option.

Edit:
[www.alibaba.com]

This is the kind of printbed I have in mind. The ideal (albeit optimistic) setup would be that, use the center hole as the 3rd mount point, drill two new mount points up from the corners (you can also see the white border), and then figure out how to manage the power supply bit. Is this possible?

Try looking at a Solid State Relay these can be driven by your Rumba board easily and still switch the high current dc that you need They are available in various Current rating's

Doug]]> dougal1957 Controllers Thu, 27 Nov 2014 07:22:56 -0500