ACME threads and QTC pill

manoloco

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Curt, a couple of topics regarding durability and operation of the pocket line of lights:

-Would it be too difficult/elevate costs too much to machine ACME threads in the pocket lights? (Eiger, Logan, Etc) they are more resistant and might make operation smoother.
-Like you wrote and DUMDUM posted in another thread, the main problem of the QTC pill to operate smoothly is that the discs dont keep parallel and touch bypassing the QTC material too soon. after some use it becomes noticeable, according to your tests the compression is the same, but i could be related to a lot of things not necessarily only to elasticity/compression, might be how the material repositions after use.

I have found that the pill of a Gen 2 Eiger QTC works really good after a lot of use if i replace the QTC material circle with one i make with enough diameter to almost fill the little hole/identation in the disc, this helps as the wider the QTC material the more stable against tilting the disc is, also filling the hole more helps stability.

I dont know if the bigger QTC circle solution will be long lasting until the QTC material holds (which would be ideal), but in the case it doesnt maybe you already have plans to make a smaller diameter/width top disc on the Eiger but with the same size hole for QTC material, i know the reasons you havent changed those is because the size availability and the bigger the material is, its a lot harder to compress, making the operation uncomfortable and impractical.

Have you found a solution for the Logan?, i think the pill needs resizing to its internal parts to work smoothly over time and use, maybe same measurements of the top disc as the Eiger and the rest be like current gen2 Logan pills?

Back to the Eiger : If the bigger diameter QTC material solution holds great i will post pics for other users, specially the tool to make them which is easy to get, i just use the opening of the tip on a parker pen (i think its the garden variety Jotter model, but the old ones with a plastic half, the all steel ones have a hole too small), the only drawback with this method is that the leftover cannot be used for the Logan pill as current size circle allows.

So far i have been using it a LOT both twisty and momentary (the fact that i like to play with the lights during the day like having a tic helps the testing) and its holding up really good.
 

PCC

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ACME threads are coarse compared to threads normally used on these lights. Peaks are cut at 30TPI and the finest ACME threads are usually fairly coarse at about 20 TPI, I think.

On my first generation Peak QTC pills I've actually placed a thin piece of tape onto the side with the impression on it to prevent the light from bypassing the QTC material and results in a smooth ramping.
 

manoloco

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thanks for the info on threading, sure ACME are less threads per inch as the trapezoidal section would take a lot more space than a triangular section, however its a lot less prone to deformation and should take abrasion with less effect on twisting.

The tape solution surely works for smooth ramping, but i like the pill to have the max output failsafe. The tape should take some compression off, at least minimal and that could prevent the light from going full output (but it might not be noticeable at all).
 

manoloco

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I am going to try the tape too, so far the bigger circle has been doing fine, some jitter a couple of times and then back to normal, opened it and some debris of the QTC material was on the disc making contact too, your tape solution definitely prevents this too.

The bigger circle of QTC on the Eiger seems to prevent the bypass of the QTC material, the only problem i see with that now is the residue of QTC material also making contact, maybe its the tool i used to cut the QTC square leaving a rougher edge which lends to the material more prone to leaving residue.
 

peakfreak

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its true that the key to smooth ramping seems to be fine threads. With coarse ones the parts travel farther with less twist. Recently got a quantum DD from steve KU which has flawless qtc opperation and the threads are a big part of the reason. When I look down into it the qtc material is totally exposed within a washer of some sort. The thread stack is also very long so the barrel travels far and slow. Im convinced that the pill will ramp much better the thinner the threads. not sure what the tpi comparison i but I'm pretty sure peaks lights have fewer.
 

PCC

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There's two reasons that the Quantum DD ramps smoother and I'm not sure which one is responsible for that: it's using 0.5M threading (50.8TPI) vs 30TPI on Peaks; the Quantum DD is direct drive and this means there's no electronics to get in the way. This last point is probably why the QDD can turn on so low so easily as the boost driver in the Peaks requires a certain amount of voltage before it will start working then it wants to ramp up quickly from there (yes, this is an over simplification, but, you get the idea).
 

mhs

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From my experience I totally agree that both thread type and presence of boost driver can affect ramping smoothness. After lot of experimenting I can say the best are tight threads that require more turning action to get to max output(like in Quantum DD) - it makes ramping more accurate. If ramping is smooth but too quick, there's a trick to improve this: if there's enough space to work at the bottom of battery compartment, you can try inserting spring that will absorb part of force and will make ramping more precise, but I'm afraid in any peak flashlight it will cause exposed o-ring issue.
Once I've made direct-drive light with spring-equipped momentary QTC switch that required ~5mm piston travel to get from 0 to 100% and it was so precise, it was ridiculously easy to set and keep any desired brightness level just by thumb pressure. Unfortunately, it's very hard to find a spring that will have faultless dimmensions/stiffness ratio to work properly in such setup.
 
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