Making momentary pushbutton tailcaps

[BC0311]

Daniel, I just got back from dropping my twisty in priority mail to you. No hurry on getting it back, though. I'll send you a Paypal shortly.

The twisty is one of J.S. Burley's that still has the anodizing on the innards and threads I think. So it don't work yet.

I'm really looking forward to this kewl number, much thanks to you and unnerv.

/ubbthreads/images/graemlins/clap.gif

Britt

 

[gadget_lover]

The good part is that the annodizing will be removed from the inside when I drill through. /ubbthreads/images/graemlins/smile.gif

The other good part is that I won't need to strip the annodizing to make sure that it fits.

Daniel

 

[gadget_lover]

OK. Key learnings from my first few mods;

First, let me say that I post these things to share with others ideas that they may want to implement. Sharing information is a great way to get new features in general use, and to improve the usefullness of existing lights.

The picture below is the same mod done to a head that has deeper milling around the lanyard connection point. Notice the very small button. It works, but is not as usable as the 1/2 inch wide one. It has to be adjusted to just 1/4 turn from the on position to allow you to use the ball of your thumb. Anymore than that and you have to use your thumb nail to press it down far enough.

I do not recommend that you use such a small button.

I also struggled a bit with the o-ring. I tried making a groove for the o-ring and having it ride in the same hole as the rest of the stem. That produced too much friction and thus a stronger spring under the button to push it back when you release thumb pressure. This required even more thumb presure, making it unusable.

So I settled on using an o-ring that rides between the inside of the tailcap and the flange of the button. I machined a slight recess in the tailcap for the ring to seat in. It should be reasonably water resistant, but I would not go swimming with it in my pocket.

The other thing that should be noted is that I'm using the hole through the tailcap as an electrical contact. Every once in a while it flickers when you push the button. Screwing in 1/8th turn usually fixes it. As a friend said, it might frustrate someone using it for morse code, but was acceptable for normal use. The other trick is to simply push the button off center to make sure it touches the side of the bore. Polishing the bore and the button helps.

Springs and things; The spring that presses against the battery will determine how much force is needed to press the button. It's not easy to balance the requirements of (1) easy to press and (2) won't turn on from casual contact with pocket contents and (3) will return the button to it's normal position after pressing it.

I'm spraying the button and cap with Caig Progold G5 to maximize the electrical connection.

Daniel

 

[PEU]

Hi Daniel,

do you have some raw schematics of the tailcap button?

I want to try it for my work in progress flashlight.

Thanks in advance


Pablo

 

[gadget_lover]

The dimensions are not critical. Here's the measurements from one of my prototypes. The tailcap has a .501 inch hole drilled in the exact center.

The little nub in the middle is simply a piece of plastic or wood turned down to about .005 smaller than the hole that it's in. The spring came from a ballpoint pen. The little nub is glued to the spring with contact cement. The spring is also held in the hole by a very light application of contact cement. In this case, the hole is .165 inch diameter and the little plastic part is .160. The hole is about .250 inches deep.

The first step (.035 by .385) is the contact that presses against the battery's negative terminal.

The second (.035 by .582) is to keep the button from falling out and to provide a stop for the button so it stays on when tightened down all the way just like a normal twistie.

The third section (.235 by .499) is the same length as the thickness of the tailcaps' end. It's .002 smaller than the hole in the tailcap. The length has to match the thickness of the tailcap to get that flush fit.

Does that help?

Daniel

 

[PEU]

after reading the last post about 5 times, I re readed the whole thread and now I GET the concept /ubbthreads/images/graemlins/smile.gif

The 1st 4 times I did not understood the whole plastic nub thing /ubbthreads/images/graemlins/jpshakehead.gif

Thanks Daniel, very clever.


Pablo

 

[gadget_lover]

Yeah, the plastic "nub on a spring" is the key. It keeps the battery from making contact until you press the button. The spring has to be strong enough to hold the weight of the battery, but that doesn't take much.

Daniel

 

[jtice]

Thanks alot for posting more info Daniel,

Im gonna have to try this very soon /ubbthreads/images/graemlins/smile.gif /ubbthreads/images/graemlins/thumbsup.gif

-John

 

[gadget_lover]

I guess I should point out why I came up with the sizes I did.

let's call the left hand side the battery contact. The middle is the collar and the right is the button post. The little plastic or wooden nub will be called the standoff.

The battery contact has to be at least .030 deep to fit within the depression on the end of a CR123A battery. The duracell data sheet shows the maximaum depth of the depression as .09mm (.035 in) so I went with .035 inches.

The thickness of the collar (shown as .035 x .582 in the drawing) will effect how far the tailcap will screw in. The distance from the end of the battery to the inside surface of the tailcap is .070 in this example. If you make it thinner, make it thinner on the right side. I've one that's only .010 thick to fit a light where the ARC's circuit board is a little taller than most. The collar is pushed against the tailcap when you twist it all the way in.

The button post on the right hand part is the same length as the thickness of the tailcap's end. The tailcap was originally milled, and the raised center was left at a precise depth. The center is drilled out as a side effect of this this mod, leaving the rougher milling around it.

Electrically, the side of the button post touches the sides of the hole, providing a path for electricity. Pushing the button causes the battery contact to touch the battery while the button post touches teh inside of the hole. As an alternative, a thin spring can go between the collar and the end cap. It has to be very weak and as thin as you can manage. I had several testers try the button without the spring and no-one thought that it needed a contact spring.

The size of the standoff's hole was determined by the size of the spring I had available. The size of the standoff itself was made just a touch smaller than the hole so it can be pressed all the way onto the hole without binding.

Well, that's all. Oh, I talk about this as a "Tactical Twisty".

Daniel

 

[bwaites]

Daniel,

Would you consider just selling the buttons? I think someone asked, but I was confused by your yes answer.

I think I can handle everything but the machining/lathe work of the button itself.

If so, how much for the 1/2 inch version?

Bill

 

[gadget_lover]

Hi Bill.

There's a problem with just selling the buttons. The thickness of the tailcap's end varies from unit to unit. That makes it difficult to have the top of the button flush with the top of the tailcap without having both parts in hand at the same time. A 10/1000 inch difference is easy to see and feel.

I'd rather not sell just the button because of the possible problems. Unless you can make a very round hole it won't fit well. If you can't adjust the thickness of the tailcap's end you will probably end up with the button being slightly recessed or too high.

I hate saying no to people who want to try mods like these, but the lack of a source of new ARC tailcaps means that if it's screwed up there's no way to replace it. I HATE screwing up other people's stuff. That's why I posted all the details.

I can be persuaded to make and sell just the buttons made to spec, but I can't gaurantee the usability. Let me know if you are still interested after all those disclaimers and cautions. /ubbthreads/images/graemlins/smile.gif

Daniel

 

[bwaites]

I can machine down the height, I can drill very round holes, I just dont have a lathe.

Second, I'm actually planning on using them in non Arc tailcaps that are easily available.

Bill

 

[gadget_lover]

E-mail sent to Bill offering to build to spec.


Daniel

 

[Mrd 74]

Daniel
Is there any possibility that your button mod could be adapted as a screw-in replacement for the kroll switch on my Arc.That would cut 1/2" off the overall length.
Mike

 

[gadget_lover]

Hi Mr D.

yes, you can replace the kroll with a threaded adapter and install a similar button in the adapter. The Kroll uses 5/8 inch hole, so a threaded sleeve that's 3/32 inch thick will still allow a button just under 1/2 inch. It's centered by default.

I've dummied this up in delrin just for fun. The principles should work. You lose the clickie switch when doing that. The adapter has to be adjusted to just the right length.

Daniel

 

[PEU]

Daniel, can you post a photo of the tube viewed from the top with and without the push button placed?

I'm having some concerns about the electrical path, since this pushbutton needs to fit like a glove or you lose contact with the body.

What do you think its going to happen with use?

And what you think on using a poron (arc aaa ring material) nub instead of the coil+wood/delrin? less volume, less problems.

Thanks

Pablo

 

[gadget_lover]

Hi Pablo.

The use of a closed cell foam should work well enough. The problem with foam in general is that it does tend to shrink and compress with age and use. Open cell foam does not always spring back all the way.

Yes, the button has to fit like a glove in order to work properly. I think I mentioned that somewhere. I'm turning them to within a few thousandths of an inch. A spring between the collar and teh tailcap should ensure consistant contact at all times. I haven't needed that so far.

I don't know how much wear you get with aluminium against aluminium. I would guess that pressing the button a few times a day would mean it's used 1000 to or so times per year. I imagine there would be some wear.

What do you mean by "post a photo of the tube viewed from the top with and without the push button placed"? Do you mean the tailcap?

Daniel
(I've been out of town, sorry about the slow reply).

 

[PEU]

yes Daniel, the tailcap /ubbthreads/images/graemlins/smile.gif

Thanks

Pablo

 

[andrewwynn]

Any chance you could make one small enough to fit in an AAA body? I have a couple AAA bodies that have extra material on the back you could actually cut off to make the button from.. the design and implementation is a work of art. They are made of brass.. the tail now has a post sticking out with a hole for a ring.. i'd rather find a different mounting solution.. even if it's a micro screw like a triple aught threaded in the side or something so i could stand it on the bottom.

I have two.. maybe a trade could be had?

I have had at least one request for a momentary tailcap button for the peak aaa mod i'm working on.

-awr

 

[gadget_lover]

I'll post the tailcap pictures in a bit, Pablo.

I'm not sure how it would work in such a small space as an AAA body. The contact area would be rather small. The clearances would be rather tight. The resulting button would be very small.


I'm planning to make a 2 AAA light soon styled sort of like the Dorcy AAA with removable head and tailcap. The tailcap will be threaded into the battery tube, sort of like a minimag, so it will have smooth lines from end to end. I should see if I can manage a momentary button cleanly in a tailcap that small.

Daniel