Successful Bolt Mod - Ultra Classic

avivey

25 Dec 2021, 22:34

(Sorry - no photos, I wanted to be done quickly)

I finished a successful Bolt Mod today on my 2015 Unicomp Ultra Classic. Figured I'll share some thoughts...
  1. I counted a total of 58 plastic rivets. 8 are right on the bottom border of the plastic panel and I figured there's no way I can drill them or hold a bolt in them if I did.
  2. I Bought a ~$120 drill press for this job. Important notes:
    • To improve accuracy of the drill, increase the drill speed. Counter-intuitive, but it works. Also chuck the bit as far in the chuck as it will go, and google "how to remove wobble from drill press."
    • Line up the drill so that the bit is just a couple of millimeters from your plastic panel - as close to the work as you dare.
    • The drill bit will actually drift along the panel's plastic. If I could, I'd dig a cavity into each hole location to guide the drill to the right place. As it is, I pushed the drill faster then comfortable to make sure it dug in correctly.
    • I used a 2mm metal drill bit; A wood bit might be better at not drifting, but I couldn't find one this small.
  3. I ended up using 8mm M2 screws for all the holes. Some guides recommend 10 or 12mm screws for some parts, but I didn't feel the need.
  4. To line up the layers, I've realized I can add screws ahead of time to the front of the keyboard, and hold them in place with tape. I used 12mm screws for this in the center row.
    I then placed the rubber liner in place (without the springs yet), and checked for alignment; I've added another screw in any hole that seemed like it might not align properly. I was tempted to just add all the screws this way, but got lazy. Also, I drilled at least one hole so far from its intended location it was left unused, and if I'd pre-screw it I might have ended up with undue stress.
    Then I placed the steel plate on top of these screws to check the fit.
    The tape only really needs to hold the screws own weight. A chopstick is handy to rub the tape between the keys.
  5. After adding the springs, liner, membrane and still plate, I tightened these line-up screws temporarily - ending up with a mostly-put-together keyboard, so that adding more screws and flipping it over to tighten them was easy.
    I've used tape again to hold the final bolts in place before tightening.
    Once most/all the bolts were in place, I've replaced the temporary line-up bolts with shorter, final, ones.
  6. I've put all the (final) screws in from the back-place side, with the bolts on the plastic side. In most tutorials I saw people insert the screws from the plastic side, with the bolts on the back plate, but this way feels better to me:
    • The screw heads are not as tall as the bolts, at least on my stock (measured about 0.5mm difference). The back side is more-or-less flush against the case, so keeping it short is important. On the top-side, there's much more clearance for the bolts - even using longer bolts wouldn't be a problem.
    • The bigger bolt gets more surface area on the soft plastic then a screw-head. You could get that with another washer, but that gets tight w.r.t. mounting the nut on the remining bolt length.
  7. I overtightened all the bolts in the first assembly. Eventually, I've settled for tightening the nut with a driver without adding any counter-force on the bolt from the other side (the tape might provide some force); When I felt the bolt turn rather then tighten, that's it. It feels solid enough, but I guess time will tell.
Over-all, it was long but not insanely long. I'm not sure I could have drilled straight enough holes without the press (as it is, I'm not really happy about some of the holes).

I can feel a difference in sound and maybe feel from my unmodded keyboard, but I can't say one is any better then the other. The one I modded actually failed - The 2 rivets holding the membrane connectors together broke. I'm not likely to mod a working keyboard, but I'll be happy to do this again for a keyboard that needs one.

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