How much boring to fit a protected 18650 in a 6P?

[Vermonter73]

How much material would I need to remove to fit a protected 18650 in a 6P? I don't have a 6P yet. Does the head and tail come off to allow straight-through access for sandpaper on a drill?

 

[mrartillery]

Yes head and tail both do come off. I think most people use a 19mm drill bit.

 

[precisionworks]

most people use a 19mm drill bit.

+1

The max diameter is 18.4 mm, so anything that's 18.5 mm or larger should be good. Either a 19 mm twist drill or a 19 mm reamer.

 

[Kestrel]

I'd recommend reading this thread, which includes the post below:
(The thread also includes a link to average-measured-diameters for specific brands of 18650's)

The OD for a typical SureFire 6P (measured at the thinnest point, the tail o-ring grooves), is ~0.771" (19.6 mm) with a wall thickness of ~ 0.042".

Taking the ID to 0.734" (18.6 mm) results in a wall thickness of 0.0185". IMO this is optimum for the AW 2600 mAH 18650's, providing a clearance of only ~0.006" (~0.003" on each side) for my particular cells.

Taking the ID to 0.741" (18.8 mm) results in a wall thickness of 0.015".

Taking the ID all the way up to 19.0 mm would result in a wall thickness of only 0.011", ~1/4 of the original wall thickness. This is the same thickness of a typical paper business card, which would concern me with regards to structural strength.


(regarding HKJ's cell measurements), The OP does need to consider what cells he will be using.

Does the head and tail come off to allow straight-through access for sandpaper on a drill?

Edit: Also, I wouldn't bore straight through the body, the drop-in functions best if a small lip is retained in the head end for the drop-in spring to reference off of. A friend of mine did a body straight-through and he has connection issues.

 

[precisionworks]

Taking the ID to 0.734" (18.6 mm) results in a wall thickness of 0.0185".

18.6 mm does sound like the perfect number. A 47/64" twist drill will make a hole .7344", or 18.65 mm.

 

[ejot]

18.6 mm does sound like the perfect number. A 47/64" twist drill will make a hole .7344", or 18.65 mm.

This is exactly what ElectronGuru ships, and it is perfect!

 

[darkzero]

This is exactly what ElectronGuru ships, and it is perfect!

Not always. 18.6mm may be a tight squeeze for some AW P18650-2600s (some may not even fit) & if one is using Pilas they might not even fit at all. With batteries a very tight fit is not ideal cause if one end is air tight causing a vacuum, the cell may not slide out easy which can be nuisance.

Remember they are 18650s, but add the thickness of the shrink wrap variances, contact strip for the protection circuit, labels (of course they can be removed) & you end up with cells that are very close to 19mm.

IMO 18.8mm is more ideal to be "universal" for fit but as the other's have pointed out since the OP is modifying a light, adequate wall thickness needs to be accounted for. If the ending wall thickness is that critical for this light I wouldn't mess with trying to drill it with a drill bit unless mounted in the tailstock of a lathe. But if the OP has access to that it would be best to just use a boring bar.

 

[wquiles]

Here is how I did them last time:

First used the boring bar to verify a centered body - just taking a very light cut:

Then I did a pass with a 23/32's (46/64") S&D drill and then a second pass with a 47/64" S&D drill (If I recall correctly done at 550RPM) using AccuLube LB2000 cutting fluid:

Fit is very nice, and not tight at all:

My notes and measurements (they do make sense in my head!):

 

[saltytri]

I must be missing a fine point here. Why use S&D bits at all? Why not do it exclusively with the boring bar? To maintain consistency from one unit to the next?

 

[precisionworks]

Why not do it exclusively with the boring bar?

A twist drill that has sharp lands can do a good job enlarging a hole, and takes almost no time. Same for a reamer except that the reamer is more accurate for final diameter & leaves a nicer finish.

 

[maglitesux]

This is the cheap, fast, and easy way to do it:

Use an electric drill, 3'' bit holder, and 1/4''- 3/4'' step drill bit ($6.99 at Harbor Freight) http://www.harborfreight.com/1-4-qu...r-inch-high-speed-steel-step-drill-44460.html

Use a vice to hold the 6P and bore straight through the body with the step bit. This is the way I did it and the 18650 fits great, and has the same space between the battery and tube as my MTE SF-23 and Ultra Fire WF-501B. A small lip will also remain to hold the drop-in spring at the head.

 

[bshanahan14rulz]

Just reminding OP about the 17670 option.

 

[lemlux]

magnetlitesux:

What a great, simple idea. I don't play with my tools very often, so I had never heard of a step drill. I went out and bought the drill today and successfully drilled out a 6P body, a3P body, and all 6 of my A19 extenders. The 11/16 level oriented the drill perfectly and the 3/4 level cut through evenly. I kept withdrawing the drill and saw that it kept centering perfectly.

I could only find a 2 7/8" extender and a 6" extender. The 2 7/8" extender went all the way up to the chuck on my 3/8" drill in the 6P and left a ledge that was about 1/2" long. The spring on my LA worked perfectly to reach the flat top 18650 I tried.

Tomorrow I may be brave enough to thry the 6" extender on the first of my 3@ P9 bodies. I won't take a chance with the thin flats on my D2, D3, and C3 bodies.

By my calculations 3/4" = 19.05 mm -- Close enough to 19mm when the thin tail threads are at risk only at the beginning of the drilling process.

 

[maglitesux]

Thanks,

I will post some pic's the next time a bore one out.

 

[Tekno_Cowboy]

18.6 mm does sound like the perfect number. A 47/64" twist drill will make a hole .7344", or 18.65 mm.

I use a 47/64" reamer, and it works very well. I found I get much better results running very slowly and using lots of cutting oil.

This size allows for most cells to fit, but even with this size, I would say that the walls are no more than 0.020" thick under the o-ring.