Instruments

 Another side task, mounting the instruments. As mentioned before I'm reusing the speedo, rev counter, oil pressure gauge and temperature gauge. These used to be in a nice self contained unit, but as always I want to make things a bit more awkward for myself!!

They do split up quite nicely, I just needed some way of mounting them on the dashboard. First step was to fix them to a back panel, similar to how they're done on the MX5. In may case I just wanted a flat panel, preferably plastic as I don't want wood anywhere and metal would be conductive. So I managed to find a chopping board that worked out quite nicely!!

I'll trim it down a bit, but at least this is the four gauges fixed together in the positions they are going to be on the car. Next step will be to cut corresponding holes in the dashboard, trim them with the 3D printed bezels that I had designed a few weeks back, then put some clear plastic in front. Then with the aid of some aluminium brackets, this panel will be mounted directly behind the openings, then wired up.

As a precursor experiment, I also 3D printed some round sleeves to go round the dials. I wanted to know the minimum thickness of plastic that would be rigid enough. I printed three sleeves between 1mm and 3mm wall thickness. 1mm is too flimsy, it'll just distort and fail. 3mm is really solid and possibly overkill for this. 2mm is good though, sufficiently rigid without being excessive. I'll build a suitable sleeve to go from the bezel to the gauge. 

I also need to mount some illumination for the gauges. At several points there are openings for filament bulbs to sit and light up the gauges. The MX5 cluster had them in the right places, I just need to replicate the process then power them along with the side lights. Or at least I think it's the side lights, it might be the headlights. Basically those dash lights will be the lights-on 'telltale' required by IVA. 

I also need to make some stand offs. To give the speedo enough room, the other dials are raised by 11mm. In most cases this is covered by the standard mounting hardware, but the rev counter doesn't have anything comparable so I need to make some small sleeves to go round the bolts. I suspect more 3D printed options will be fine. 

The other indicators (fog, hazard and main beam) will just be individual panel mounted lights, I'll see what's for sale at the kit car show for those. 

Oh yes, the kit car show, a little over two weeks now. I need to get my shopping list sorted. 

(Update). As with the wheel arches entry I've decided to continue adding to existing posts rather than jump back and forth, it might be easier to read. 

The board is now cut with everything in the correct position;

I also 3D printed the bezels that will sit behind the glass and body;

To box it in behind the dashboard I have some old aluminium that is big enough;

That will be cut and folded to box in the instruments. In the above picture you can see some X's on the board, that's the bulb positioning. The MX5 use this type of bulb;

But they twist into a panel and connect to the conductive sheet that is on the back of an MX5 dash. My panel is thicker and doesn't have the circuit behind it, so I've ordered some rubber equivalents that do the same job but just push fit into the panel. They also have flyleads which will make it easier. Hopefully with the dials boxed and bezelled I can add a decent amount of illumination and it won't leak through anywhere it's not supposed to. I might even add a few extras to make it a bit brighter. 

Next bit will be the glass face and the decorative edge on the bezel. Perspex for the former, 3D printing for the latter. Then Tigerseal/rivnut into place, and job done. 

(Edit 03/06/24). Well, things are never straightforward are they?! Silly me forgot that I'd braced the bodywork with a steel bar, just inside the edge of the dashboard. As the gauges and the brace can't occupy the same space, it means that I need to rethink the mounting. I still want it to be boxed in, but it now needs to be slightly lower. And because it's slightly lower, the two smaller gauges no longer fit. I'd have one poking out the bottom of the dash.

However, the dash illumination thingies have come;

I think they're going to be perfect. They're cheap and nasty, and have a really weird internal structure, but when the bulb is inserted they do exactly what I need them to do. I have ten leads total, but only six bulbs for now. I intend to fit them all to the back board, hopefully they will look decently bright. As they will be enclosed, the light will only come out through the gauges themselves. 

Back to the gauges. I have an extra board to mount things on, or I could go for two separate enclosures. I have all the material required, it would just be not as tidy as having them all as one. 

I've also remembered something else about the dashboard, the two switches I need. Again the kit car show failed to provide, only one vendor selling parts so I ended up not getting any switches. I'll have to see what I can find online.