Mini-Mag modification to eliminate head wobble

Have any of you done this, or toyed with the idea?

The idea is to machine a second o-ring channel in the barrel of a Mini-Mag, just aft of the head seal o-ring, such that, the two o-rings together might stop the notorious Mini-Mag head wobble by stabilizing the head in the longitudinal axis.
I was thinking of this as a fix for the focusing mis-alignment/wobble while using a high dome luxeon on a MadMax+ sandwich, with NX05 colimator.

I think if the o-rings are lubed, it would still turn fairly easily.

I always peel out that o-ring, and clean the o-ring, the channel, and inside of the head with alcohol. This is how I leave Mini-Mags that have the NX05 in them. There is no need for focus, but I do remove the head occasionally for candle mode, so not much of a problem there.

Now for a Mini-Mag that will be used to focus, this is a bit much, but it gets me to a starting point to re-lube, very meagerly, until the head turns easily enough for use, but not so much that I think I might lose it, or have to re-focus it for each use.

The C & D cell Mags have that finer thread, and it seems, closer tolerance of manufacturing that keeps them at the focus you left them with, but the Mini-Mags are much looser.



The other complaint I have with the Mini-Mag/LED mod combination is the head screwing down too far, and turning the light off.
This might fix that as well, if left unlubed. It might have enough tension to keep the head from moving.

On one of my MadMax+s, I am going to use the 2 AA series brass collar & button as a stop for the head, in addition to being a mode of carry for the light.
If a small dimple is made in the barrel of the light, where the set screw touches it, the collar will neither rotate nor slide, and will make an excellent stop.

I use two wraps of teflon plumbers tape around the head threads. Makes all my Mag heads rock solid and also makes the screwing down smooth and firm.

Wilkey

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Ginseng said:
I use two wraps of teflon plumbers tape around the head threads. Makes all my Mag heads rock solid and also makes the screwing down smooth and firm.

Wilkey

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That's exactly what I do. Works great.

Hey, that's a cheap fix. I'm trying it.

Thanks for the tip.

Hold on a minute with the teflon tape here. How well does it transfer heat? Remember that most mods rely on the Mini-Mag head to be a part of the heat sink, and by adding teflon tape (or anything else) you may be making the heat path more difficult.

Just my $0.02. If you do try it, please report your results here.

Yes, that is a good point, especially since I'm looking for a relief from head wobble with an R2H on a MadMax+.
It gets quite hot due to the low forward voltage.

I think I may try to cut this groove into the barrel myself.

a thicker oring is really your best bet...

Yes, Rothrandir, I think you're right. I'm going to try that first.

/ubbthreads/images/graemlins/grin.gif

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shankus said:
Yes, that is a good point, especially since I'm looking for a relief from head wobble with an R2H on a MadMax+.
It gets quite hot due to the low forward voltage.

I think I may try to cut this groove into the barrel myself.

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I thought that a low forward voltage LS in a constant current circuit would mean that it heats up less?

not really, because it's being overdriven harder than a higher vf would be...

My mistake - MaxMax is actually a voltage regulated circuit.

Well, first of all, the teflon tape is pretty thin. Like super thin. When you take the head off, the tape usually comes off like pieces of thread rather than a thin film. Second, since the LED is mounted inside the body tube, most of the heat will transfer down that path and into your hand. I agree that it would be nice to have heat go into the head...and it does. I found that I can't tell the difference by sensing temperature with hand whether there's Loctite, teflon tape or nothing on the threads.

A thicker O-ring? Another good idea that's cheaper and faster than any machining. Good suggestion Glow-Boy! /ubbthreads/images/graemlins/grin.gif

Wilkey

I epoxy all of mine, which also have Krolls installed. No wobble plus good heat transfer. There's no longer a need to focus.

Teflon is a well known electrical insulator, and there seems to be a relationship between electrical and thermal insulation.

Teflon is a great insulator and there is a relationship between thermal and electrical conductivity. However, the tape I use mics out to 0.09mm/3.54 thousandths. The thermal conductivty of 0.25 W/mK is of course much lower than that of metals (about 1/1000th of Al), but about midrange for polymers. High Tc epoxy has a thermal conductivity of about 1.9 W/mK, about 7.6 times teflon so still far below that of metals.

The key considerations are 1) teflon tape increases the contact area over poorly intermeshing threads 2) in the absence of any filler material, epoxy or teflon, the gap will be air, a decent insulator. All in all, the thermal barrier of teflon or any plastic in such a thin layer is probably close to being offset by the more intimate contact made. Do I have data? Sure don't but this makes sense to me.

Wilkey

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Otokoyama said:
There's no longer a need to focus.

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Actually, with a high dome & the NX05, it focuses nicely.

That's the main reason I was interested in stabilizing the head on the Mag.

The wobble of the head can toss the beam around, and contort the beam quite a bit.



The idea that the teflon would conduct the heat better than air seems right to me. I hadn't thought of that.

I guess it is easy to try it both ways.

There have been many good comments in this thread. It is helpful to have you guys to bounce ideas off of, and to have suggestions made that didn't occur to me. What a great forum, huh?
Thanks guys...

The double o-ring trick worked very well for my first L/S mod I called the X Oracle. The focusing optics would really get messed up if the lenses were not aligned and the extra o-ring fit the bill because there was a grove I was able to use to seat the o-ring. I think Elektrolumens is doing this or was with the Oracles he was moding.

shankus: I see. I've been using only LDs with the NX05, and once I find the tightest focus at ten feet, I epoxy.

Though it requires machining, I'd opt for Wylie's double O-ring. Some of my C and D Mag head threads are so loose that the single Mag O-ring seems to only provide a fulcrum for the wobbling, making it difficult to get a clean, circular beam. Teflon tape is a great idea, but on mine many wraps do not cure this. A tight, lubed, double O-ring should be able to return the head to center after focusing.