Countersink

Hi everyone,

I wanted to ask what people were using, I guess what fastener and the size of the countersink they were using, when fastening power resistors to aluminum beds and if you getting a really flush surface. Any tips or hints would be great.

Thanks for the info.

bdc
~stay calm out there

I did not countersink any bolts but here are some pics of how I make the resistor heated bed.

[www.flickr.com]

I use very small screws (#4-40 in my case). First I positioned the resistors, then I drilled and tapped the holes. On mine I use heatsink compound but I am not sure it is necessary.

I hit 130c with these beds with no issue.

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www.Robosprout.com RepRap Mendel parts and accessories.
Message if there is anything you need...I have more than what is listed on my site.
Located in the Spokane, WA / Coeur d'Alene, ID area.
Contact: Robosprout@gmail.com Flickr: [www.flickr.com]

i just use a bigger drill bit, i set the depth on my drill press. then go slow.
take away any ridges. its covered with kapton tape anyway.

i really like cecil,s setup i may try to emulate on the next one.

I over countersink mine as I put glass on my heated bed so as long as the bolt heads are below the surface all is good. I use M3 10mm countersunk bolts and heat sink compound to make sure I get a good connection

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Experimenting in 3D in New Zealand

Dang Cecil. That's a hell of a setup. I think it might be simpler just to tap the holes, like you did Cecil.

Thanks for the input guys. One more thing, what power resistors do you guys like to use? A particular manufacturer? Definitely going to have to new a new head bed build.

bdc
~Stay Calm Out There

I use these Here

I only use 4 of them as they easily get up to the 55C I need for PLA and the temp is nice and even across the bed which is 5mm Aluminium with 3mm glass on top

Edited 1 time(s). Last edit at 02/29/2012 06:39PM by NelsonRap.

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Experimenting in 3D in New Zealand

The bed I use is basically a copy of Arcol's heated bed ( [blog.arcol.hu] No pics right now for some reason).

I use the Vishay/Dale 10ohm 10w aluminum body resistors.

[search.digikey.com]

My old bed uses 9 of them and hits 130c in 10-15min (with 5mm aluminum bed with 3mm of glass) I use natural wool felt on the bottom as an insulator.

My new bed has 10 resistors...I hope it will get just a touch hotter. The only problem is it draws 12A of current which means it is over what RAMPS can draw so I am running it with a relay off the RAMPS bed output. 9 resistor version draws 10.8A which is right below the fuse point.

Also, with a resistor type heated bed you can rewire it in series and run AC through it. Just be sure to add a ground to the bed.

Edited 2 time(s). Last edit at 02/29/2012 08:28PM by C. Cecil.

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----------------------------------------------------------------------------------------------------------------------------
www.Robosprout.com RepRap Mendel parts and accessories.
Message if there is anything you need...I have more than what is listed on my site.
Located in the Spokane, WA / Coeur d'Alene, ID area.
Contact: Robosprout@gmail.com Flickr: [www.flickr.com]