I've never seen design #4 offered in my short time here but I can see how it would be useful if you were designing a custom PCB or hard wiring a board together. Outside of those two options, I see no benefit over design #2 or #3 since most PCBs can only have switches soldered in one specific orientation.
OP, here is how your post looks on the Nostalgia (default) forum theme:Show Image(http://i.imgur.com/uEgCRNR.png)
There should be no difference between cutout #2 vs #3 in terms of stability. If you look at the sides of a cherry switch there is no plastic material positioned in a way that can utilize the metal "tab" that exists in design #3. Its just extra work for the laser cutter.
IMO, design #2 is the most optimal. The layout is such that almost every part of the switch housing that is designed to rest against the plate will be utilized while still remaining open on the sides to allow for switch modding. Of course design #1 covers the switch as completely as possible but the stability factor should be virtually identical between #1 and #2 due to the design of the switch housing.
#2 and #3 should allow 90 degree switch rotation, but you can't open it without desoldering, and (to my knowlege) have never been implemented in such a way.
* for those that allow modding, this means allow rotation and preserve ability to allow modding.
Lastly, shapes 2 and 3 are similar, but 2 seems like it may be cheaper to laser cut (less time) at the cost of a bit of stability. Comments?
If you look at the sides of a cherry switch there is no plastic material positioned in a way that can utilize the metal "tab" that exists in design #3. Its just extra work for the laser cutter.Yes there is. The side-tabs of #3 do touch the switch's sides, but the corners do it just as much. If the side-tabs were slightly wider than the norm, they would provide more stability than the corners.
Let me propose yet another shape: an H-shape without the tiny tabs in the corners would have just as many cuts as #2, be just as stable and provide not much more gaps than #3 but it would also allow rounder corners which could possibly make it even cheaper to CNC-mill.
Anyone want to make a plate and test it out?
Doing lots of modifications to switches without desoldering seems like a pretty niche use case to me (it’s not like desoldering is especially hard), so personally I’d just as soon stick with #1, unless making a keyboard aimed at geekhack folks.
This is Findecanor's suggestion:Show Image(http://i.imgur.com/iMuILbI.png)
Anyone want to make a plate and test it out?
I'm attaching a drawing file for anyone who is interested.
I still think though that if the plate is made with high tolerances the top and bottom edges by themselves should prevent all twisting and the side tabs should only prevent the switch from being rocked sideways.
I laser cut a few of these cutouts onto some cheap eight inch hardboard/masonite to test them out, including the new H-shaped one. They are pretty loose though since hardboard isn't a very precise material for laser cutting, the burning made the cuts wider than I wanted. With the loose holes the one with both corners and tabs is the most stable, with the H cutout being the least stable.Why can’t you just account for the width of the laser when you make your design? I don’t think “imprecise” is the right word here. Or did you make a bunch of test cuts sending the identical shape to the laser and find that the result was different each time?
Why can’t you just account for the width of the laser when you make your design? I don’t think “imprecise” is the right word here. Or did you make a bunch of test cuts sending the identical shape to the laser and find that the result was different each time?
I think the center portion on jdcarpe's model needs to be wider to create more contact area with the side of the switch.
I made some measurements and drew up the following. The left is the final dimensions. The right allows for 0.008 laser kerf in 1/8 acrylic (not sure if trishume's is same).
@trishume I am curious as to how the cuttings time compared for the three shapes you cut.
I just laser cut some test patterns in 6mm/0.2in acrylic. I tried them with varying dimensions so that I could test the fit of the switches. When I directly printed jdcarpe's cutouts they were too loose so I tightened the cutouts by varying amounts. It turns out insetting the edges by 0.2mm gave me results that fit the spec so that is the reference point. Here are the fit results:Can you measure the actual final dimensions with some calipers? Different laser cutters might have different kerf, so folks probably want to compensate for that.
0.551 ± .002 inches, with a 0.012" max corner radius
plate thickness 0.06 ± 0.004 inches
http://media.digikey.com/pdf/Data%20Sheets/Cherry%20PDFs/MX%20Series.pdf
I would like to ask out the various cutout shapes I've seen in the various custom plates that have appeared on GeekHack. Below is a drawing with the 4 cutout shapes I have seen.
(Attachment Link)
Here is my understanding of the differences:
Allows Switch Can Rotate Mounting
Modding Direction *
--- ----------------- -----------------------
1 No Yes
2 Yes No
3 Yes No
4 Yes Yes
Is this correct?
It seems like the reliefs added to allow for modding would reduce the stability of the mounting, as the lateral reinforcement of the switch decreases. I.e. the switch might be more prone to wobble. Is this true?
Lastly, shapes 2 and 3 are similar, but 2 seems like it may be cheaper to laser cut (less time) at the cost of a bit of stability. Comments?
* for those that allow modding, this means allow rotation and preserve ability to allow modding.