Heat sink diy

[michäel2]

hi all,
im planing of making a set of heat sink and I'm looking around at the different design one could go with, and that raised the following questions.

first of, is the idea to have as much contact area as possible and as much brass in there, as in brass absorbs the heat and as such the more brass the more heat it can absorb ?
in that case i would go with two round halfs of brass like in the photo below:Screenshot 2015-08-16 19.06.16.jpg

or should i put a bitt more effort in and go with a design that has a few more cuts in its design and as such looks like it can radiate the heat better ?like the one's in this photo ?Screenshot 2015-08-16 19.15.11.jpg

what ever design i will go with it will have to be able to purge as well.

i don't quite know the nitty gritty about how these puppies do there job and i hope perhaps someone here can explain it to me, i have used the search function on heat sink but no price (-:

thanks, mick van aar

[roadrashdave]

I got some stuff from a company FOC recently to build my jig

He sent me these plans to make mine on a lathe.

http://bicyclemanufacturing.co.uk/wp...BML-HS-100.pdf these were downloaded from the link ,cut copy and paste it in your browser and it appears

Cheers

Dave

[Mark Kelly]

Further to Mike's lovely drawing:

There is no appreciable radiation or convection from the heatsink so, unlike most things called that, it is truly a heatsink. Accordingly you want to be able to conduct heat into it and for it to have a high thermal mass relative to the part being cooled. The first is a function of surface area in contact and materials, the second is a function of total volume and again material.

On the first, since steel and especially stainless have fairly poor heat conduction, area will trump material: as long as you use something with decent conduction like brass or bronze you'll be OK. Accordingly, any cutouts or other fancy engineering must serve to improve the contact area by allowing the heatsink to conform to the part being cooled, otherwise they're pointless at best.

On the second, thermal mass (more properly volumetric heat capacity) doesn't vary much between different solids*, again if you stick to brass or bronze you'll be right. As above, cutouts etc mostly serve to decrease the available volume so they need to have a very good reason to be included.


* the range of VHCs for solids is between about 1.2 and 3.6 and the very low ones are things you're not likely to use like bismuth and antimony. For things you are likely to use the range is about 2.4 to 3.6. Copper alloys are at the high end of the range so go with them.

[michäel2]

thanks Mark for the answer i was looking for !
and thanks dave and Alistair (i really like the use of spoke for the retaining rings, i was wondering what i was going to use for them ) for some excellent designs.
i know what ill be doing the next couple of weekends!
this forum has again proven to be an excellent resource !
mick van aar

[Jonathan]

i think you guys are missing one fundamental requirement for most of these commercial heat sinks, the ability to flow argon when welding.

[Mark Kelly]

That was taken as read from the OP:

what ever design i will go with it will have to be able to purge as well.

Argon is too expensive to use as a coolant.

[Alistair]

You may find this flickr set to be of some help,

https://www.flickr.com/photos/duncan...57632976565126


Alistair.

[VertigoCycles]

hi all,
im planing of making a set of heat sink and I'm looking around at the different design one could go with, and that raised the following questions.

first of, is the idea to have as much contact area as possible and as much brass in there, as in brass absorbs the heat and as such the more brass the more heat it can absorb ?
in that case i would go with two round halfs of brass like in the photo below:Screenshot 2015-08-16 19.06.16.jpg

or should i put a bitt more effort in and go with a design that has a few more cuts in its design and as such looks like it can radiate the heat better ?like the one's in this photo ?Screenshot 2015-08-16 19.15.11.jpg

what ever design i will go with it will have to be able to purge as well.

i don't quite know the nitty gritty about how these puppies do there job and i hope perhaps someone here can explain it to me, i have used the search function on heat sink but no price (-:

thanks, mick van aar

I realize that I haven't actually contributed anything to this thread before losing my patience with Mark.

Either one of the designs you posted (the bottom photo is mine) will work great. My photo only shows the actual heatsink portion and not the rest of the tool that makes it work. I would hope that was obvious but wanted to state it in case it's not.

From a fabrication standpoint, it would be much easier NOT to build them they way I have, and to just slit them into thirds or quarters and use a spring clip. This goes double if you're using the internally relieved Paragon head tubes. I'll add that make sure to leave a generous ID on the brass (or bronze) portion to allow the tool to contract enough to easily remove it after welding. The 510 bronze that Paragon uses is much springier than the 660 bronze (and lends itself better to making the spring type heatsink) that I usually use BUT it's very hard to machine with the machine tools most framebuilders have access to. If you go with the 510, make sure you have some serious power at your disposal and get your speeds and feeds dialed. 660 is much easier to machine but makes a huge mess since it essentially turns into powder. When I made mine years ago, I used a very clean mini shop-vac to suck up the chips as they were coming off the lathe tool.

You should be able to make exactly what you need using Alistairs link. IMO, he did a fantastic job putting his tools together as well as documenting the process.

[Amaro Bikes]

Just in case it's helpful, here is a picture of some of the nice ones made by Sebaudet, I'm pretty happy with them, thanks again Seb

They're cut in thirds as Sean said, have the purge fitting for plug easily with the argon tube (dedicated back purge bottle) and have some generous mm travel margin so you can make presure without risk of getting blocked after welding. Here are the BSA BB and 44mm HT ones, then there's another one for ST

Cheers

[Alistair]

You should be able to make exactly what you need using Alistairs link. IMO, he did a fantastic job putting his tools together as well as documenting the process.

Thanks Sean. For the sake of completeness, and because I'm fascinated when it comes to bike fabrication to know the history of who invented what, or came up with a particular method, I should say that I made those heat sinks after consulting with you via email on how you made yours. You made me aware of a couple of issues that I hadn't considered at the time (three years or so ago?), so thanks again for that info.

I also got some good insight from Kris Henry's Flickr page (44 Bikes), by looking at the process pic's he had posted of how he made his heatsinks.

Anyway, just wanted to mention that.


Alistair.