Zer0 Posted February 20, 2011 Share Posted February 20, 2011 If i wanted to make an acrylic housing setup for a 10x10 heatsink, would the dimensions need to be this for all of the pieces to fit perfectly flush with the heatsink? 1/2" thick, black acrylic. 2 pieces 11" x 4" and 2 pieces 10" x 4" Would that make a perfect fit around the 10x10 heatsink? Only reason i want it to be 4" tall is because i need to mount a fan on there, and i don't want anything sticking out of the fixture. The heatsink is about 1.5" thick, including the fins. Thanks for reading. Link to comment
RK_tek Posted February 20, 2011 Share Posted February 20, 2011 Those dimensions would be correct until the temperature changes. Acrylic's coefficient of expansion is about 10 times that of glass. It's possible that if you made it when the acrylic was warm, it wouldn't even fit when cool. Link to comment
Zer0 Posted February 20, 2011 Author Share Posted February 20, 2011 Those dimensions would be correct until the temperature changes. Acrylic's coefficient of expansion is about 10 times that of glass. It's possible that if you made it when the acrylic was warm, it wouldn't even fit when cool. It's 1/2" thick acrylic... i doubt it would expand and contract considering LED's give off very little heat. Right? Plus.. why would i build the housing when the acrylic is warm? I'm buying it pre-cut from a website, cut to those exact dimensions. Link to comment
blibo Posted February 20, 2011 Share Posted February 20, 2011 contract considering LED's give off very little heat. Right? Wrong. Try touching one after an hour or so... Link to comment
LPS-Crazy Posted February 20, 2011 Share Posted February 20, 2011 Wrong. Try touching one after an hour or so... ^^^^^ Why do you think LED's need a heatsink in the first place ? You may be thinking about the light produced which does not generate radiation, which does not put heat in your tank. Link to comment
Zer0 Posted February 20, 2011 Author Share Posted February 20, 2011 So... 1/2" thick? Or thicker? Or should i ditch the acrylic idea all together and go with something like sheet metal or aluminum? Link to comment
LPS-Crazy Posted February 20, 2011 Share Posted February 20, 2011 Not saying it wont work, just commented on the heat thing....But why take the chance of making this baby and having it fail right ? Aluminum would be the best option, but then how do you assemble if you dont have a drill press and equipment to thread it for set screws ? Maybe you do... If you end up going aluminun, make sure it gets painted...Saltwater likes to pit aluminum. Link to comment
Zer0 Posted February 20, 2011 Author Share Posted February 20, 2011 I don't have a drill press or access to one. What should i use to make the housing? Link to comment
TheWAND Posted February 20, 2011 Share Posted February 20, 2011 I don't have a drill press or access to one. What should i use to make the housing? Wood will work at the temperatures LEDs run at. You will just have to vent it well at the top. Link to comment
LPS-Crazy Posted February 20, 2011 Share Posted February 20, 2011 I don't have a drill press or access to one. What should i use to make the housing? Check out PVC sheet....You can use pvc for hot water aps and never have a problem so I dont think it has the same properties as acrylic when it comes to expanding. There are several places you can buy PVC sheet online. Look into it first though, this is only a idea. Link to comment
LPS-Crazy Posted February 20, 2011 Share Posted February 20, 2011 Check out PVC sheet....You can use pvc for hot water aps and never have a problem so I dont think it has the same properties as acrylic when it comes to expanding. There are several places you can buy PVC sheet online. Look into it first though, this is only a idea. But yeah, nice sanded wood with carfully applied coats of high gloss black paint or stain could look sexy also. Easy to built, easy to find the materials...Everyone knows someone with a table saw (even the #######s that wont let you cut it on "THEIR" tool") wll due for this project. Link to comment
glazer Posted February 20, 2011 Share Posted February 20, 2011 Personally, I think you are being overly concerned about the acrylic. True, it can expand and contract with temperature but there is hardly a material made that doesn't. Depending on the wood, it can expand/contract a 100x + that of acrylic. I don't know what you're design is so wondering why "exact" measurements is so critical... I'm thinking it's more about since you are ordering the pieces pre-cut. The biggest worries would be how accurate the person cutting the acrylic is. If you need a piece exactly 10" who's to say the guy cutting it isn't going to be off by a 1/16". How do you plan on mounting the box to the heatsink? Strictly by friction? It's open-topped and you're just framing the heatsink so to speak? What would be the problem with just oversizing your requested cuts by a 1/4" ? Why do you need to use 1/2" thick? Quarter inch is probably way more than adequate... well, I think. Just not enough info on this project of yours. Got a drawing? Steve Link to comment
TheWAND Posted February 20, 2011 Share Posted February 20, 2011 Personally, I think you are being overly concerned about the acrylic. True, it can expand and contract with temperature but there is hardly a material made that doesn't. Depending on the wood, it can expand/contract a 100x + that of acrylic.I don't know what you're design is so wondering why "exact" measurements is so critical... I'm thinking it's more about since you are ordering the pieces pre-cut. The biggest worries would be how accurate the person cutting the acrylic is. If you need a piece exactly 10" who's to say the guy cutting it isn't going to be off by a 1/16". How do you plan on mounting the box to the heatsink? Strictly by friction? It's open-topped and you're just framing the heatsink so to speak? What would be the problem with just oversizing your requested cuts by a 1/4" ? Why do you need to use 1/2" thick? Quarter inch is probably way more than adequate... well, I think. Just not enough info on this project of yours. Got a drawing? Steve All that acrylic flexing can lead to ugly cracks. Link to comment
Zer0 Posted February 20, 2011 Author Share Posted February 20, 2011 Personally, I think you are being overly concerned about the acrylic. True, it can expand and contract with temperature but there is hardly a material made that doesn't. Depending on the wood, it can expand/contract a 100x + that of acrylic.I don't know what you're design is so wondering why "exact" measurements is so critical... I'm thinking it's more about since you are ordering the pieces pre-cut. The biggest worries would be how accurate the person cutting the acrylic is. If you need a piece exactly 10" who's to say the guy cutting it isn't going to be off by a 1/16". How do you plan on mounting the box to the heatsink? Strictly by friction? It's open-topped and you're just framing the heatsink so to speak? What would be the problem with just oversizing your requested cuts by a 1/4" ? Why do you need to use 1/2" thick? Quarter inch is probably way more than adequate... well, I think. Just not enough info on this project of yours. Got a drawing? Steve Well, i've ordered acrylic sheets from this place before and they were always cut to exact measurements. I think they cut with the blade thickness in mind to get exact measurements. And no, i planned to drill the acrylic in to the sides of the heatsink. It wouldn't just be mounted by friction.The reason i saw exact measurements, is because i think it would look nice to have the acrylic sit flush with the heatsink, and it would also be easier to put a screw through the acrylic and in to the heatsink if it sat right up against the heatsink. I want to use 1/2" thick because that's pretty thick stuff, and i doubt the heatsink would get hot enough to warp 1/2" thick acrylic. Especially if it had two fans mounted on it. All of the extra circuits and drivers will be in a separate control box so it's not like i'm going to have a ton of things running on it. And yeah, i was thinking it would be open top. I don't want to cut out pieces of the acrylic for the fans, so i'll leave it open. But their will be a clear acrylic splash guard on the bottom of the fixture. No drawings, sorry. Does this clarify enough? Link to comment
glazer Posted February 20, 2011 Share Posted February 20, 2011 No drawings, sorry. Does this clarify enough? Yup, got it. I went digging through my pictures to see if I could find one of a similar housing I built and no luck. I framed out a heatsink with 1/4" black acrylic like you intend to do. Difference being I oversized the frame by a quarter inch and used spacers in between the acrylic and the heatsink. I enclosed the top but had a fan mounted in it blowing out.. the quarter inch gap around the heatsink served as the air inlets to cool the thing. Splash guard also mounted with spacers.. but whatever, just a thought and I understand what it is you want to do. Personally if it were me I would oversize the acrylic frame by a few hairs (hairs of your choice) just to make sure when you glue up the frame it will indeed fit around the heatsink. Remember you have to figure in exact cuts, their tape measure versus yours. Another thing to consider is just because they say 1/2" acrylic doesn't mean it's exactly 1/2". Thickness can vary across the sheet. Granted we're not talking a lot but it all plays into "exact". Anyway.. for what it matters, you have my blessing to proceed with the acrylic. haha Steve Link to comment
Rabidgerbil38 Posted March 13, 2011 Share Posted March 13, 2011 If you dont mind me asking, where did you find a 10x10 heatsink? I've been looking for one for a while now, an am about to give up and make my own.. Link to comment
herranton Posted March 13, 2011 Share Posted March 13, 2011 If you dont mind me asking, where did you find a 10x10 heatsink? I've been looking for one for a while now, an am about to give up and make my own.. http://www.heatsinkusa.com/products/10.000...g-Heatsink.html Link to comment
thewire Posted March 15, 2011 Share Posted March 15, 2011 Some people are just giving the wrong info....look at the acrylic shield that used on T5HO lighting and those PC lighting...did they expand? You can buy the plexi UV treated too.... Link to comment
disaster999 Posted March 16, 2011 Share Posted March 16, 2011 if you are using a fan, i dont think you have to worry about the heat issue at all. i have a 12"x4.5" heatsink with 17LEDs running at 650mah each on it cooled by a 12v 80mm fan running at 5v. the fan cools it down so much its only slightly higher than ambient temperature. i tried unplugging the heatsink and let the fixture fun for a few hours. it got pretty warm but not hot enough to cook anything. turned the fan back on and within a min or 2, it was right back down at room temps again. i'd say 1/2" acrylic is overkill, you can get by with 1/4" or thinner. your just framing the heatsink, not building anything structural with it. just make sure theres enough ventilation holes for the air to flow through and your good Link to comment
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