# 2.75C hotwire host for 2x26650 cells with AW switch



## wquiles (Mar 20, 2010)

I recently got a customer ask for something new to me, and since this is not a complete host/project but purely a flashlight machining project, I figured I would post it here.

- Cut 3C Mag to fit 2x 26650 batteries
- Internal boring to fit 26650 battery
- Head grooving
- Deep tailcap mod

Since the customer wanted the shortest host possible, I waited until I got the actual cells in hand before starting. Here you can see, from left to right, the large "F" cell, the new IMR 26650 cells, the AW 26500 cell, and the AW LiIon cell:







Close up pics:











I checked the diameter of the new cells with my micrometer to get an idea of the widest point, so I checked various cells at various places:


























These cells are a "tad" larger in Dia than the 26500 cells that I have:











So the size of the cells is fairly close to their "spec", diameter-wise:












Now to work on the body:












Here is the 3C host next to the with the two 26650 cells:






I checked their overall height:











and also checked each one on a "plastic" caliper (probably needless to say, but NEVER attempt this on a metal caliper!). These cells are definitely longer than their spec (calls for a max. of 2.57"):











So individually they came to 5.246" and on the height gauge they came up to 5.250", so I went with the 5.250":






These cells are too fat to fit inside the tailcap, so to make the overall even shorter, I will take off a "little" bit of the tailcap length (more on this later):






And the tailcap spring needs to be pushed inside fairly deep - the tailcap mod will take care of this:






So per my data, the overall length (tube only) needs to be 7.9":






which is about "here" (marked by the smaller ruler):






However, the parts that you sent me to use include the AW switch:






So I compared it to the stock switch, which is longer by about 0.2":












So I ended up cutting the tube even shorter since the AW switch was shorter (7.7"):






I measured the amount to bore internally (about 5.6" to the switch), and then setup the boring bar for this job. Due to the overhang I had to take light cuts, and extra "spring cuts":
















I first prepared the area to be threaded:






and then did the internal boring (very slow work):






Then came the threading part:











the o-ring bevel:






and here is the completed tube/host:











Here I am making the tailcap a tad shorter:






and then doing the deep tailcap mod - note the cell ends right in the thread area:






and we only need this small part of the spring to lightly compress the cells:






almost done:






Then I did the head grooving (note coolant drop on second pic!):











Completed host:











Will


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## 65535 (Mar 20, 2010)

Very nice work there Will. Getting some very nice finishes on these PM machines.


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## mrartillery (Mar 20, 2010)

Nice work! Makes a cleaner look than the deeper tailcap.


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## wquiles (Mar 20, 2010)

Thank you guys 

I attribute the good finish to a couple of factors:
- gibs are fairly nice and tight everywhere
- using Al-specific inserts
- 1200 RPM spindle speed
- except for the long inside boring operation, very little tool overhang on all other operations
- lubrication (Accu-Lube LB-3000) with approx. 90 PSI or compressed air keeping all debris away from cutting surface. I feel that this new lubricator alone is the main reason for the finish I can get now. It is giving me better finishes than the KoolMist mister system I used before, which is even more amazing given how little lubricant is being used, and since it is not water based, I no longer worry about short/long term rusting.


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## ramlanrafie (Mar 20, 2010)

Hi wquiles,

I always admire your work and enjoy your threads. Really awesome


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## flashfiend (Mar 20, 2010)

Will, that project was just ridiculous. I feel like I just won a prize. The funny part about calling it a Mag 2.75C is that this is going to mainly be a host for the Osram 64275 bulb. So maybe that makes it a Mag 275x2.75C. Thanks again for your willingness to do this project for me.


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## precisionworks (Mar 20, 2010)

> this new lubricator alone is the main reason for the finish I can get now.


The vegetable based lubes do a nice job. Any lube that slings off the work & hits the floor is a treat for the shop dog, who licks it up like it was fine wine :huh:


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## wquiles (Mar 20, 2010)

flashfiend said:


> Will, that project was just ridiculous. I feel like I just won a prize. The funny part about calling it a Mag 2.75C is that this is going to mainly be a host for the Osram 64275 bulb. So maybe that makes it a Mag 275x2.75C. Thanks again for your willingness to do this project for me.



You are welcome


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## flashfiend (Mar 25, 2010)

Hi Will,

Got my Mag2.75C. Here it is with the FM Chrome Deep reflector.






Not as nice as your pics but I though the host still looked pretty sweet.

Thanks again.


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## JimmyM (Mar 25, 2010)

Really nice work, Will.


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## wquiles (Mar 25, 2010)

Thank you guys


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## Tom Anderson (Mar 26, 2010)

JimmyM said:


> Really nice work, Will.



+1 :thumbsup:


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