26/24/22mm ring-style contact board MK2: dremel mandrel filing support

“~~**v13 - https://oshpark.com/shared_projects/VI4y6Ihm**~~”
EDIT: See post #14 or later for current version.

This is the latest major revision of my multi size contact board. The contact boards we traditionally used waste a lot of space and typically do not allow you to make what I consider a clean install. It also affects your ability to properly cool anything which heatsinks onto the ground ring.

As an alternative I suggested an adapter ring style board, like this:

26mm to 20mm

From there I fleshed the board out with tabs to allow (relatively) easily filing the inside to accommodate a 17mm driver or a 20mm driver. I also added guide rings to allow filing down the board from the outside for 26mm, 24mm, or 22mm. If you want 23mm you’ll still have to eyeball it :wink:

26mm to 17mm

The current revision, v013, has a four-spoked center area which is attached to the the actual ring with [my attempt at] break-routing tabs. I used two 0.7mm vias to create the break areas. The center of this section has a 1.6mm (~1/16in) hole for use with a dremel mandrel. You can easily use it with a larger mandrel by drilling the hole out to your desired size. At that point you just press your file against the board and go!

A friend of mine suggested this change after I showed him the design, I think it’s a good idea. The implementation may not yet be perfect.

The thread to check about earlier versions of this board is Cereal_killer’s 26mm board request thread. Pics of a MK1 22mm to 17mm board are here.

Seems pretty versatile. Thanks.

The thought of all that filing made me cringe. This version only makes me cringe a little less, but we’ll see how it goes.

I certainly wouldn’t want to see a hobo coming at me wielding one of these things.

Its got four heads on it. Not sure what sort though. Thanks wight. My first order from Oshpark.

Cant figure out if that is a squished mickey mouse or a pissed off cow


Still way cool, makes it much more versatile when you can pop out the part you don’t want

I was thinking more along the lines of a puppy dog face or maybe a gang sign.

The sad puppy adapter


Looks like Mickey and Minnie had a cow. Should I add this board to the others in the Oshpark thread?

That’s fine, please mark it as untested for now. Thanks!


Hmm, oops. I made a mistake, anyone who orders v13 will not receive a center drill. No refunds :wink:

I’ll post up a v14 w/ the correction.


Why didn’t it have the center drill? It shows just fine on the render

Because it’s just a hole [drawn in the milling layer and rendered to the board outline layer, IIRC], and the hole is smaller than the minimum router bit they use for cutting holes. A slot/hole/etc is different from a drill hit. Holes are done with a router, drill hits are done with a drill.

If you wondered why I changed the inner edge of the board so much for this version, or wondered in general why the puppy-dog/cow/sheep/etc face was present, it was to accommodate the 100mil thick router bit.

They have a ton of drill sizes on that production line, from ~13mil up whatever.

Ah ok, if you use the wrong size milling layer (for the center cutout) it won’t actually be done due to it being the wrong size?

Did you have to change that circle in OSHPark from a circle milling layer to a hole layer?

we actually like the puppy-dog/cow/sheep/etc face, don’t get us wrong…it makes for a much more versatile adapter plate, we weren’t picking fun at you (other than a good friendly little ribbing)

  1. It’s a little complicated. I think the OSHPark support site goes into some detail on the matter, no time right this moment to discuss - sorry! Basically results can be unpredictable if what you specify is not possible. Better to keep your layout 100% possible for the equipment they use.
  2. here’s the fixed version - v14 - https://oshpark.com/shared_projects/O6Mj1CBD I used a 1.6mm drill hit, which is just a hair over 1/16in.
  3. Don’t worry, I took it as such! I only brought it up to point out that my design would probably have looked a little different if I had been able to use a smaller router bit.

I’ve updated the Oshpark thread with this edition(v14).