Stylus conductivity question

[Richard Dooling]

Not really a turning question but it's turners generally making styluses (yes I looked up the plural) for tablets.

I'm not a pen turner but want to make a tablet stylus for my wife. In my ignorance I simply turned a pen shape and mounted a stylus pad to the end. Of course this didn't work well because there is no metal completing the circuit with the hand. Doesn't work with a capacitive screen. Doh!

I have noticed though that some simple actions do work. Large swiping actions generally work while non-swiping point and touch actions do not.

So is there some way to have the stylus work without your hand touching metal attached to the stylus pad?

As an experiment I held the stylus tip with a paper towel insulator and it failed at most tasks. Then I held the tip with paper towel wrapped tweezers and this seems to produce better, but not spectacular, results. I have some guesses but don't know why.:confused:

Thanks Richard

[Bill Boehme]

Are you talking about a Wacom type tablet or an iPad type tablet?

I have a Wacom Intuos Pro graphics tablet and the pens are plastic ... It might be conducive plastic, but I haven't checked to see if that's the case. It also has a little switch on the side.

I had assumed that there there might be a passive circuit in the pen similar to the passive circuits used for tracking shipments or for chipping Fido and Fluffy.

I have a couple of the soft tip pens that are used with mobile devices like iPhones and iPads. You van get kits for them from Craft Supplies. I assume that the brass barrel is needed to provide capacitive coupling to the users hand. Here is information on How To Geek (http://www.howtogeek.com/115328/from-the-tips-box-diy-styluses-recycling-old-discs-into-a-game-and-searching-flickr-for-kindle-screensavers/) to make your own stylus.

[Richard Dooling]

Thanks Bill,

Should have been more specific. I'm talking about the iPad type screen.

I have seen the kits and the online videos but I was hoping I might be able to imbed something in the pen barrel to have the only exposed part be the tip.

Ah well.

[Walter Mooney]

PSI and CS both sell the stylus tips as a separate item, I think to possibly convert a pen to a stylus (or to replace them if they wear out). Do you think that might work?

[John K Jordan]

So is there some way to have the stylus work without your hand touching metal attached to the stylus pad?


The stylus for a capacitive touch screen needs to induce a charge at the surface. This is best done with the finger or with the hand in contact with a conductive material connected to a conductive pad. The conductive material is often metal but doesn't need to be - there are other conductive materials. I haven't made one with a pen kit but I suspect they rely on the hand touching the pen clip, since the stylus pad is often installed on the clip end of a writing pen.

You could paint it with a conductive paint (ugly), keep the whole thing wet (not a chance), wrap a spiral of gold wire around the shaft (stylish stylus). You can even turn an entire shaft from scratch from aluminum or brass. I've turned a bunch of both metals on the wood lathe with Thompson spindle gouges. It's slow but works well. Maybe make one with the bottom 3rd or so metal and the top wood, relying on the fingers to touch near the bottom? You might even laminate a bit of thin metal between layers of wood (glued with epoxy?) and turn so the user touches the edges of the metal strips. Thin metal could be cast in a resin and turned. You could glue conductive plastic foam around the outside with a thin wire or foil inside for a conductive path to the tip. (We used to get conductive foam from the sheets the integrated circuit chips were shipped and stored on.) I don't know of any wood that is naturally conductive once dry.

Just some wild brain-storming. Right now, however, my brain is affected by a stationary front.

Turning a shaft from some kind of conductive plastic should work or a soft conductive "rubber" - there is a bit under almost every computer key and switch these days. There are many types of conductive plastic, often used for antistatic handling and storage in industry. For example, look at the list at the bottom of this page: http://www.boedeker.com/esdmatls.htm
I have no idea where to get small pieces. I could ask my friend Joe. He knows everything.

JKJ

[Richard Dooling]

Walter, I think these are replacement tips for their kits. I bought something like this thinking the tip was all that is required. Thus my use of the ancient and honored term "Doh!"

John, thanks for a list of possible solutions. I was trying to keep the pen as an almost all wood item but I now see the error of my ways. Short of finding a clear, conductive finish (are you listening General?) I'll have to come up with some way of incorporating metal into the pen body.

Your idea of metal laminate is interesting. Maybe figure out how to cut a nice spiral and use wire as an inlay. I'll also look into the the materials you provided in your link.

Thanks guys