Heatspreader multiple layers

[Micael]

Hi, I'm going to place an aluminium heatspreader on my onyx (between onyx and the 3mm boro glass), however the best price I can get on this is to just simply buy a 2000mm X 1000mm aluminium sheet and cut it myself, so I'm going to have enough material to basically do 18 discs, so my question is this:

1) Would I see a significant difference in the heatspreader effectiveness if I used 2 or 3 discs on top of one another, instead of just using a single solid disc with the same thickness of the combined discs?
2) I see tricklaser sells discs that have about 1.6mm, I can only get it in 1mm, 1.5mm, 2mm, or 3mm (or more ofc), and I'm wondering what is the overall best thickness for a bed heatspreader, taking into account that I have an FSR system, and as such weight and rigidity end up affecting readings.

I'm sorry if this is not the right place in the forum to place this question, if it isn't please indicate me the correct one so I can close the topic and open it somewhere else.

Thank you.

[Jimustanguitar]

TrickLaser makes one. I've got two of them, they're just the right size.
http://tricklaser.com/Heat-Spreader-for ... R-ONYX.htm

I like having mine, it does help even out the temperature across the bed. The other advantage is that it keeps the print head from influencing the bed temp while it's printing the first layer right above where the bed's thermistor is.

[Micael]

Oh yes my bad, I should have mentioned the reason why I'm not buying directly from tricklaser is because I live in Portugal (Europe) so I would be paying 76$ for it, I can get the 2 meters by 1 meter with 1.5mm thickness aluminium plate for roughly 30€, so I can do more than 36 discs for the price of a single one from tricklaser, this assuming I wouldn't pay custom duties and vat, which I probably would have to.
Goes without saying my version won't be anywhere near as nice as the tricklaser one.

EDITED: BTW do you use an FSR system, if so did you notice any difference after you placed the heatspreader?

[Jimustanguitar]

You might reach out to Brian (TrickLaser) directly. Very few automated systems calculate international shipping accurately. If you want one of his, I'm sure he can get you an exact quote that's more reasonable.

[Doug68]

I think that 1.6mm is just a convenient size to get in the USA, I don't think there's anything more to it than that.
I you can get a bunch cut nicely then use one and sell the rest on eBay.

[Xenocrates]

to answer the questions

1). Yes. Multiple layers which are not thermally bonded (IE, lapped, thermal paste, ETC,) will degrade performance and coupling the the heater and sensor. Think of it as the difference between using a string of Christmas lights versus an extension cord to plug stuff in. It might work, but sometimes it will be really funky and sometimes it just doesn't work.

2) Given what I've heard, the heat spreading effectiveness is present even in a few mills (fractional imperial unit) of aluminum foil. The other property I find useful, thermal mass, is very much dependent on thickness, as the thermal mass is proportional to the weight. Thermal mass is both positive and negative, in that it takes more energy (power over time) to heat it, but it also serves to damp oscilations. If you find the wait bad, but not enough to justify a higher wattage bed, go for thin. If you plan to use a higher watt bed (24V or AC), I might pick a thicker one to damp the oscillations due to control somewhat.

[Micael]

Hi, thanks for the reply, yeah I figured it would make a difference, had also considered that the 2 discs would be thermally expanding at different rates, which might make a difference, and ofc thermally bonding the sheets is just going to be more expensive than buying a single sheet with the correct thickness.
Was mostly wondering the option because since I am basically going to be paying by the kg, and regardless of the thickness I go for I will end up buying enough material for 18 discs, if there wasn't an issue with multiple layers I could just buy it in a smaller thickness and use the extra material to make the thickness difference, basically saving money in the process.

I'm assuming the oscillation issues are diminished when using the printer in a closed chamber?

My main issue right now with deciding the thickness is mostly related to what difference it might make on my fsr setup, since it seems to me that the more weight is put upon the FSRs the more force needs to be exerted to trigger them (could be wrong), and I'm wondering if thats going to be an issue or not, I'm pretty sure I'm just overthinking things and 1.5mm or 3mm won't make a difference, since there are plenty of people with the 1.6mm tricklaser and I believe mhackney had a 3mm one (could be wrong).

I'm definitely going for a 24v setup, in fact I hope to have sometime in the next couple of weeks to make the conversation and hopefully make a post about how to source the parts in Europe on the "cheap", also hopefully highlight and fix some safety issues that I have seen in people usual setups.

I think that 1.6mm is just a convenient size to get in the USA, I don't think there's anything more to it than that.
I you can get a bunch cut nicely then use one and sell the rest on eBay.

Had considered it, but honestly doubt the rostock max v2 market in Europe is all that big (hence why I couldn't find a disc at 310mm), there is also the issue of shipping, the discs aren't too big, but its probably going to be easy enough damaged them during transportation, more importantly for buyers I don't really have the proper tools like tricklaser does to do a proper job.
Will probably end up using the rest of the material to make shelves inside the printer steel cabinet or something, since aluminium "low" melting point won't really be a problem inside of it.

[enggmaug]

I live in France, and own a V1.
How much would you charge for selling me a couple ?

[Micael]

Considering you would be paying shippings costs, I would just buy from ebay it will be cheaper and you will get a much better product, also since I haven't done it yet I don't truly know how much work it would be, but genuinely doubt it will be worth it for you, especially when you have dirt cheap discs like these:

http://www.ebay.ie/itm/1-5mm-Round-Disc ... Sw8w1X2chG sure its just 300, not 310, but honestly would be surprised if anyone was printing on those last 5mm on each side of the glass, you also have a few people in the UK that seem to cut to size, but its probably cheaper to just buy a plate of aluminium in France and cut it yourself, just avoid the general hardware stores and go for specialists, since they will be a whole lot cheaper, I know in my country they charge like 36€ for a 0.6m by 1m, 1.5mm thick in a general hardware store, while I can get a 2m by 1m, 1.5mm thick for 26€ in a specialized store.

Oh yeah since you have a V1 you need to check if your onyx isn't still one of those that has the contacts on the top, because if it is you will need to cut space for them, for obvious reasons.

[enggmaug]

Thanks, I'll look into that.

[Micael]

So I decided to follow Doug68 advice to have them properly cut, so I ended up doing a laser cut run on the plate (with single led whole, not the double led of rev8), so I should have 17 of them to sell by next week.

[enggmaug]

How did it go ? Did you sell them yet ?