Help: Using copper pipe cap as heat sink

[BrianMc]

Thanks for all the input. :thanks: :buddies: lovecpf

My pipe cap solutions for the two Marwi/ Viewpoint Bullet shaped housings are shown here:

http://www.candlepowerforums.com/vb/showthread.php?p=3217270#post3217270postcount=27

When the lenses and LED's arrive, I will post the completed units with beamshots. I'll use the MTB settings.

Google works well so no need to post all links to pipe caps here. So I guess we could close this thread.

 

[rufusbduck]

[long quote removed - DM51]

I think the easiest solution is to cut another disk of copper, lap that, and drop it into the cap and solder it. Then, drill it for your wires( being careful to dremel the burrs around the holes.

 

[rufusbduck]

[long quote removed - DM51]

I have tried cutting notches to follow the interior shape and it works but I have found that for me a better way is to heatpipe with copper nails to a copper band on the outside of the housing works even better and is much less work. I use ordinary metal epoxy with the lens, cap, and star in place to exactly locate the copper cap. Then, after it has cured, I remove the lens and star and drill through the band, housing, and copper cap, solder in a few copper nails and dremel off the excess. I also create a separate copper slug heatsink with a separate path to ambient for the driver in the same manner. This method ensures perfect alignment for the optic as well as even pressure on the star for optimal heat transfer. In still air the copper gets warm well before the aluminum housing. This is important for me as I use the old Vistalite housings with a plastic part that houses the switch. When in motion the copper conducts well enough that niether my triple cree q5 at 1A nor my quad xpg at 1.3A is more than luke warm. The quad is using a Maxflex 5 ( Kudos to Georges at Taskled for building great drivers) and it has yet to cutoff with the thermal set at 60 C. The triple cree(actually, two of them) uses one of the $12 kd p7 super output drivers which are supposed to also have a thermal cutoff but I don't know at what temperature they are set. The quad has only been finished for two weeks but I have been using the other two for the last year and can say (imho) they have been a great success and have not failed yet. My earlier attempts with closely fitted copper, a common heatsink for driver and led(mce) were less than satisfying as it resulted in a toasted led which while it lasted produced a beam not nearly as smooth as the multiple leds I am currently using. I admit I am going against common practise by running the q5s in parallel but even now I haven't been able to locate a driver anywhere close to as inexpensive capable of running 3 crees in series that I could simply pop into the vistalite using the same switch and no pot to achieve dimming. In any case, I can heartily attest to the ability of a cheap copper pipe cap as a means for those of us without access to a lathe to make more light. Mod-on

 

[BrianMc]

I think the easiest solution is to cut another disk of copper, lap that, and drop it into the cap and solder it. Then, drill it for your wires( being careful to dremel the burrs around the holes.

Good idea.

I am not sure that the 4-6% gain in thermal resistance at the interface is worth the effort I put in to that as both lights run cool enough. But for those wanting to have the copper pipe cap work at its very best, I add the following:

I solved the issue of polishing inside the caps by just using the caps reversed so I could lap their bottoms. One was made into a pill like in flashlights held in a copper liner by a ridge and valley keyway system shown here at the top of the post:

http://www.candlepowerforums.com/vb/showpost.php?p=3217270&postcount=27

The other was a pipe cap fit into the back of the body shown in the botttom of the same post.

I melted a pool of silver solder in the back of the last version to increase the radial thermal path to the light body and the solder obligingly made a negative miniscus thinnest in the center. Nice surprise. (The pill has a thick copper insert, (heavy and overkill), but it slows warm up.)

I used a hot plate to melt the solder in the cap. Worked like a charm. So I might suggest that the hole in the cap be made before the polished copper plate is soldered so excess solder can exit and not well up at the edges. Put a spiral of solder wire under the plateand place the plate/solder/cap on a hot plate. With the hole between the heating element courses. Any leaked solder will lift off the pan underneath when you are done.

If you need to enlarge the copper cap to get a good interference fit in the Marwi Bullet housing, I'd add the copper wire and solder wire around the outside of the cap to do this at the same time in one step, (if you aren't goin to use the flower petal method to expand the cap as used to shrink the backside of both my heat sinks). Drill the hole through the new added bottom from its side to reduce burrs. Then file and sand the enlarged cap cicumverence to get a nice snug fit. Some Arctic Alumina, and all will be well.

Or for the Marwi Bullet light, just cut a 5 mm thick slab of aluminum bar a bit bigger than the ID about 32 mm for a slug. Drill a hole for wiring and any screws then sand to fit and polish as much as you want. Arctic Epoxy it at the depth you need it up to 20 mm. Done.

 

[DM51]

rufusbduck, it is unnecessary to quote entire posts, especially where they are lengthy ones. A brief extract is usually sufficient.

 

[BrianMc]

I have found that for me a better way is to heatpipe with copper nails to a copper band on the outside of the housing ... less work. I use ordinary metal epoxy with the lens, cap, and star in place to exactly locate the copper cap. Then, after it has cured, I remove the lens and star and drill through the band, housing, and copper cap, solder in a few copper nails and dremel off the excess. I also create a separate copper slug heatsink with a separate path to ambient for the driver in the same manner. In any case, I can heartily attest to the ability of a cheap copper pipe cap as a means for those of us without access to a lathe to make more light. Mod-on

Great addition to this thread for others building lights.

+1 on Pipecaps. Also search CuLite on MTBR for making the entire light of copper pipe fittings.

I can attest to the hours spent dremeling and grinding copper heat sinks for a tight fit with Arctic Alumina to fill voids. Definitely a drawback of the tight fit method, but it too made cool running MR11 lights (about 7 square inches of air interface) with minimal air interface.

The radial distance the heat has to go has an effect. More smaller sources of heat closer to the outer part of the light are going to move heat better than one hotter on at the center. Taskled recommends the LED and MAxflex not share a common thermal path. Based on my lights you could have stuck with the tight fitting pipe caps and been succesful, but less work is a very nice benefit.

Is the Vistalight an MR11 or is it larger? Any pics to help others do this too? How many copper nails? Did you concentrate them in line with the LEDs? What was the total cross section of copper heat pipes/nails? Did you do an entire ring for the Maxflex heat sink or just the one point? The list goes on. Please, we want some more!

For those reading this thread for ideas on using pipe caps, a blend of the two would also be possible, though the nails alone can make for successful heat management. You could solder segments of straightened copper pipe straps (Mueller makes them about $1 for five) outside the pipe cap running axially at the points where the LEDs will be radially. Then you only need sand these wider heat pipes to fit the case, not an entire enlarged pipe cap. Much easier. Much less work. The nails could be used as rivets/heat pipes to an outside copper ring and/or an aluminum motor heatsink for some mods. Use silver solder, it conducts heat better.

 

[rufusbduck]

I use Vistalite housings for a few reasons which I will cover as they come up.
For a quad xp-g mod I used one 1" cap and several sections of 3/4" copper pipe. I cut around the cap~ 5/16" up the wall and soldered inside a smooth piece of copper flashing cut a little undersized as a disc to fit inside the cap. Then I cut the remaining section up one side and opened it into a u - shape and soldered slugs cut from female thread copper fittings(the curve of the threads already fits the housing shape) inside the ends of the 'u'. I set these parts aside and make the heatsink for the driver next(Maxflex 5A in this case).
Using a small copper pipe cutter, I cut several 3/16" sections of 3/4" pipe(six or so) and a couple more of 1/2" pipe. Then I remove sections of the pipe so that I can reduce the radius and make two nests of copper rings( one goes inside the housing, one outside). If you heat the copper with a torch it looses its temper and gets more pliable. With the torch again I heat the slugs and solder them up. for this I use plumbing solder as it's cheaper than electrical solder and easier to apply in somewhat larger quantities.The Vistalites have a ring in the bottom which helps center the exterior slug if you allow on of the rings to protrude from the nest. Next I grind away as much of the interior aluminum ribbing as I can with a dremel leaving enough to secure the interior base nut and the switch support. I again use the dremel to fit the interior slug over the base nut and remaining aluminum. I epoxy the two slugs in place with jb-weld and drill two 1/8" holes all the way through both slugs and the housing and solder in two copper nails and cut the excess of inside and out. A small copper tab sized to fit the Maxflex soldered in completes this part( and raises the pcb to clear the pcb solder connections.
Back to the led heatsink. With the interior slug in place, I grind enough of a bite shape out of the pipe so the sink, star (quad xp-g r5 32mm from cutter) and focusing fit loosely behind the lens retaining ring. I drill a 5/16" hole in the center of this part along with two 1/8" holes that line up with the screw holoes in the housing and smooth this with the flat surface of the dremel grinding disc (I keep an assortment with various states of ware to fit in small places) and some wet/dry paper. Butter up the outside edge of this part with jb-weld and drop into place, add star, lens, and retaining ring and apply pressure frome the inside out(toward the retaining ring) until its set. Fit and epoxy the u-shaped hoop to the indents on the outside of the housing (looks like it's wearing earmuffs). Then drill a 1/8" hole through each 'ear' and solder in a nail. The jb-weld conducts heat less well than the copper nails thus somewhat isolating the two heatsinks and by allowing the led sink to fit loosely there should be a small space between the two.
The switch is another reason I like the Vistalites. The stock switch will work with most of the dx and kd drivers to change modes and power on/off and digikey has an exact fit replacement for a momentary n/o switch to operate Taskleds UI Uni software. The wiring is difficult in such a small case but possible if you cut away the mr-11 plug base part of the switch module.
Before assembly I throw on some undercoat and flat black paint and start cramming. The switch wired to the maxflex goes first with some aa to that tab I mentioned before. After that sets, preload the screws in the case and reattach the back of the case using the two 1/8" holes drilled for this purpose. With some thermal grease on the sink(not the star or it could foul the led leads) carefully slip the leads and star into place(twist the star back and forth to spread the grease thin). Solder, add lens, cover and power and you're ready to rock.
I use the original 6v nightsticks for the kd drivers but for the maxflex I made up a pack of nimh cells in an 8s 2p arrangement for 9.6 v to get as close to the minimum voltage for 4 xp-gs as possible. Level 1 is ~ 40-50 ma which corresponds to a forward voltage of 2.5-2.6 v. So, 4 x 2.5 is 10v so even at the lowest setting the maxflex should regulate(and does) and still keep me ~ 2a to the driver on high running at 1.3a to the leds.
I am 50 and my night vision ain't so good anymore and these lights make all the difference. I wanted to do this to see if I could make something pretty nifty for not much $ without having access to a lathe. Don't get me wrong, I drool with the rest over some of the awsome work that shows up on this site but I couldn't help myself. Does this make me a flashaholic?
If you're curious there are some pics on the mtbr site in the homemade lights database and I'll be posting some here soon if there's a need.

 

[BrianMc]

I use Vistalite housings for a few reasons which I will cover as they come up....I am 50 and my night vision ain't so good anymore .... I wanted to ...make something pretty nifty for not much $ without ...a lathe. Don't get me wrong, I drool ..over ...the awsome work ...on this site but I couldn't help myself. Does this make me a flashaholic?
If you're curious there are some pics on the mtbr site in the homemade lights database and I'll be posting some here soon if there's a need.

Closer to 60 than 50 here, I'm afraid. Legally blind without glasses. I also need more light!

Many of us are tool deprived or challenged yet want something in alight tht no one is making. Or recycle a faithful friend which has lighted the way. Copper plumbing parts are a very viable route.:twothumbs

You can just copy the shortcut(s) of your post(s) in MTBR to your edited post above to add pictures, if that would be easier for you. (Right click the post number in the thread and copy shortcut and past it where you want it in case you did not know).

 

[pe2er]

I Think this is the RufusBDuck posting: http://forums.mtbr.com/showpost.php?p=6359844&postcount=60

Except that this is a triple, not a quad...

 

[rufusbduck]

Yeah, that's one of the earlier models but it 's still going strong and kicks butt on even a 20 w halogen bulb that tends to cook the plastic in these lamp heads. The quad xp-g is only just finished and I wanted to test it on a ride or two before I showed pics. The copper tabs that you can see above notched through the pcb are where the copper nails are drilled and soldered all the way through from the outside. This one was modified without epoxying the inside copper before soldering and this made it very difficult to achieve good pressure on the pcb with the lens and holder.
I am a fan of medium beam lenses and the old halogen bulbs lit up just too small of an area with the spot and flood bulbs were too dim. I was running one of these vistalite mods on the bars with a ledil cute-3 med and one on my helmet with a cute-3 ss but now I have both of these on the bars with medium lenses and the quad xpg on my head. I figure 6 xr-e q5 at ~ 200 lumens each plus 4 xp-g r5 ~ 420 lumens each at 1.3 A means I'm in th vicinity of 2800 -2900 lumens with some pretty inexpensive lights.
Here are some numbers on the cost:

Q5 Triple
kd driver $12
3 q5 from dx ~$17( I bought 5 packs)
pcb from Cutter $3-4(price has gone up)
1 " copper cap $4
3/4 " copper pipe $free for me but only $1-2 for a foot
awg 20 Teflon wire $5 will get you plenty
solder ~$5

Total $46

For the quad xpg I purchased the leds preloaded from cutter with a gt4-xp lens ~$45 with shipping and a momentary switch from digikey for ~$2 and a Maxflex 5A from Taskled for $35 so the cost for the quad was a bit more at around $85-90 as I already had the solder and wire.

One thing I should mention about those inexpensive kd drivers is that I am unable to run them using a remote switch as interference causes the lamp to cycle between high and low every few seconds. I solved this problem by separating the driver from the lamp head but the idea was to minimize the crap on the bars while making it easy to switch levels without taking my hands off the grips to reach the lamp. Georges at Taskled mentions a pullup resistor on his flex drivers to allow for longer switch wires but his switches don't control main power. I have a Hipflex that I can use to drive both lamps if it comes to that but was hoping to avoid gutting the drivers from the lamps. Ideas anyone? I have two nightstick batteries from which I removed the five 2200 mahr sub-c cells and replaced with seven 2000 mahr 4/5 sub-c cells so I have the power for the hipflex already.
It should be pretty obvious that the copper is an insignificant part of the price but as far as I'm concerned makes this particular mod work. Would love to hear any suggestions for improvement as I these sets still show up frequently on ebay.

 

[rufusbduck]

One thing I should mention about those inexpensive kd drivers is that I am unable to run them using a remote switch as interference causes the lamp to cycle between high and low every few seconds. I solved this problem by separating the driver from the lamp head but the idea was to minimize the crap on the bars while making it easy to switch levels without taking my hands off the grips to reach the lamp.

I have found a solution to the problem with remote switches. I had been using the stock Nightstick 6V batteries but I believe these KD drivers work better with SIX or more nimh cells. I went ahead and tried the KD driver with the seven cell sticks I put together for the hipflex and it worked just fine even with two feet of cable between the switch and the lamphead with the driver inside. Tried it again with just six cells and still no problem.