LP12 next step

[andyr]

So this is the part I'm having trouble visualizing. I understand about drilling a larger hole and putting in some tubing. What I'm not visualizing is how the bolt head is going to secure against the armboard or what the tubing is doing.

OK, perhaps I can explain it this way:
* the normal way is to drill holes through the armboard to match the spacing of the holes in the Cetech.
* then you put bolts through the holes in the armboard & the Cetech - so you have:
- on the top: bolt head then washer (to spread the load) then armboard
- on the bottom: Cetech then washer (to spread the load) then lock-nut.
* so the washer under the bolt head is resting on the laminate top-skin of the armboard ... and as you tighten up the nuts underneath, if you go too tight then the bolt heads/washers will be stressing the laminate top-skin of the armboard.

What I am recommending is:
* find some thick-walled metal tubing. It needs to have:
- an ID sufficient to pass the bolt through
- an OD which is just a bit wider than the bolt heads.
* so the bolt heads will sit on top of these 'collars'.
* then drill out the holes in the armboard sufficient to take the thick-walled metal tubing.
* cut the thick-walled metal tubing into lengths which are just a tiny bit shorter than the thickness of the armboard.
* so when these metal 'collars' are epoxied into the armboard:
- the top of these collars is flush with the top of the armboard, but
- the bottom of each collar is just shy of the bottom of the armboard (so they don't interfere with the armboard contacting the Cetech).

I can see how one could easily damage either the armboard or the sub-chassis. The sub-chassis may be rigid, but it's just honeycombed aluminum and is easily mangled. I'd think that I'd want to tighten the bolt down snug and possibly have a lock washer on the underside of the sub-chassis. And perhaps some lock-tite on the bolt/nut connection, so that once it's secure, it stays that way.

I think the Cetech is more fragile than an armboard! 🙂
Yes, have a lock-washer under the nut ... or use those lock-nuts which have a nylon insert which stops the nut unwinding.

If you don't want to bother with the thick-walled metal collars then just make sure you don't wind the nuts up too tight. You want them tight enough for the armboard to make a rigid connection with the Cetech ... but you don't want it to stress the top of the armboard.


Andy