Metal/epoxy moulding and other things

 I'm sure I'm missing a few photos, but here's what happened...

Firstly I modelled a gas cap neck end in Onshape and printed it out;

Once I'd checked it worked ok with the cap, I printed a negative, basically a mould;

(The real thing would not have photographed very well, even this 3D model is difficult to visualise). . Then with nearly a full tube of JB weld I filled the mould;

I did try some release agent on the mould, hence the discoloured wood that it's sitting on. Unfortunately the release agent did very little as the epoxy had managed to get in between the plastic threads. At least I knew it was a good adhesive!!

Once it had cured, I set about removing the mould. It had to be done essentially one layer at a time, and in doing so I actually broke the thing I was moulding. That was a little disappointing, but more epoxy and I was able to get it back to it's final form. This is the original printed version alongside the new moulded version;

And... it does work surprisingly enough. It's certainly strong enough to cope with holding the cap on, it needs some fine sanding just on the edges to make the action smoother though. The epoxy worked so well that it duplicated the 3D print layers, which means the surfaces are rough.

Of course, in the meantime I did find a filler neck for a Royal Enfield bike that could actually do the job, so I have one of those on order. If that arrives and works I'll use that instead.

In other news, the gauges are progressing well. I'm adding paint on the bezels now;

A bit more sanding, painting, sanding and painting will get me some decently smooth surfaces. I've also cut and polished the acrylic faces;

I needed a lot of elbow grease and some watch face polish (polywatch is the name). It worked well to be honest, it got rid of most of the hazing. There's still a few tiny marks but hopefully they won't be seen once they're mounted in place. 

I've also added one layer of knifing putty to the hub caps, once they're dry I'll need to sand them;

By the way, knifing putty is really hard to work with. But on the good side it does mean it'll be quite tough. It needs a good sanding and shaping, and for some reason I'm missing one. I only had three when I came to do the putty work. 

And lastly, an update on wiring. It's horrible. That's the update. I can see why it's left until the end, and many builders opt for an aftermarket loom. However I do have most of it done, I've got maybe a dozen wires left. I've temporarily mounted the two fuse boxes in roughly the same position they will be in the car;

The spaghetti is what I need to get rid of. There's two main power feeds that go to most of the sensors and connectors, then there's fuses for a few extras (EG fuel pump). Many of the fuses aren't used anymore, if I put my mind to it I could have replaced both blocks with a smaller unit. But for now I'm staying standard with all the challenges that brings.

Oh, and Mr Insomnia kicked in last night with an interesting question... where did the dashboard connectors go? I've got the one for the ignition switch, but there's one required for the indicators and one for the lights. Oh, and the horn (why do I keep forgetting the horn?!). From my 'donor photos' I can see three connectors that look like they would have been at home on the column;

Two white connectors and one black. Hopefully they will match up with 'something' on the extracted loom!

Another fail (fuel tank filler)

 It was all going quite well so I was bound to trip up on something. The plan for the fuel filler neck was to weld a plate to the end of a tube, then cut it to shape. Actually, scratch that, the original plan was to buy a filler neck, but it turns out the ones I was watching on Ebay are the wrong size. So the alternative was to DIY it.

The job started ok, once I'd ground back the welds I could see some pinholes so that wasn't a surprise. Cutting the end hole to size got the cap on, but it wasn't tight enough. Regular fuel filler necks have a gentle slope to pull the cap tight so I had to replicate that. Not too bad, a few taps with the hammer and I got the right angle to pull it tight.

Problem is this is where it came unstuck. I'd effectively broken the welds to make the slope, so it was no longer one piece of metal. And of course, now everything was thin, welding just became a game of 'chase the blow through'. Unfortunately while other locations could tolerate blobs on the other side, as soon as I had one weld on the inside the end became useless. 

So it's back to the drawing board for this one. The issue is that I need to have a flat surface on the top for the cap to seal against, but then a sloping surface for it to tighten up against. And everything I can come up with either covers one or the other, not both. 

My next thought is some form of mouldable metal to make the shape, something like SteelStik or cold weld from JB weld. If I 3D print a mould I reckon I could get it quite accurate, but would it be strong enough? I'd add a flange to attach it to the body, and if it was strong enough I could attach the fuel pipe straight to it. I'll see how good my 3D skills are first! 

New toys

 First an update on the tank. It was another miserable welding job, I hate working on metal that thin. Loads of pinprick holes that needed rewelding. But I finally got it done and pressure tested. This is just before welding it up, showing the flexi pipe in it's proper home;

I think it looks perfect, and it's clear of the roll bar brace. After this picture was taken I welded it up, painted it and put it away ready for the other end.

Oh yeah, the other end. So this arrived;

£40 for an vented lockable gas cap and this cover that goes on top. I don't know whether this particular cap is IVA friendly, if not I'll just go with the standard gas cap. Not as pretty, but safe.

Now the problem was what to fit it to. I got this first because I wanted to see how wide the cap was. Turns out it's wider than all of the Ebay bookmarked pipes so none of them are any use! However it's a perfect fit for my 2 inch tube. So the plan is to weld a flat plate to the end of the tube, then drill and cut a suitably slotted hole in the tope for the cap. Once that's done it's another bit of welding to fix a mounting skirt to the tube for the bodywork. So definitely the locost version.

The only thing I do need to consider is keeping it fuel tight (again!) and also having it perfectly flat on the face. Thankfully I have access to both sides so I'll be able to tap and bend it where required. It needs to be flat to seal to the gas cap rubber, otherwise it's going to be an instant fail. I think in theory I can put the cap on the tube then fill it with water to see if it's tight.

Last thing is the switch gear. I finally found somewhere that sold bog standard toggle switches, or at least I thought they did. Turns out they were momentary flasher switches rather than on/off! A quick disassembly and remodel of the switch mechanism got me a pair of on/off toggle switches. Then it was back to the 3D printer for a mount;

The first one on the left was just way too small in every dimension, not sure what happened there. The second centre one was better, it had the front edge trim on and it looked ok on it's own. The switches fitted, but when it came to screwing on the collars it didn't work. So another couple of millimetres in every direction got me to the one on the right. Now that's just waiting for me to add a legend and the perspex. 

For perspex I managed to get small sheets from Hobbycraft, even in a buy two get one free offer so I have some spare material. It looks ok but I've not yet tried cutting it yet, that will be the main test. If it cuts and/or grinds down then I have enough to make face plates for all dash gauges, tell tales and switches. If it doesn't then I've wasted £6, hardly a dealbreaker!

Last bit of dash

 There is one last bit of dashboard work that I need to do, and that's switches. Most of the switches are dealt with by the column stalks, so that's indicators and lights. What's missing is the fog light and the hazard light switches.

As with everything I do, I started out really complex. I had in mind that I needed IVA compatible switches that illuminate with the correct colour and symbol. Of course, in reality I didn't need it to be like that!

First thing, IVA. This is actually a simple fix, I just need to make sure the switches are in the exempt zone, which is 127mm outside of the steering wheel. Given that is pretty close to the side of the car it means I can put the switches anywhere on the right hand side panel. Which is actually where I wanted them for aesthetic reasons, it means that once again I'm able to keep the dash as clean as possible. Staying within the exempt zone means that I can go with pretty toggle switches rather than dumpy IVA friendly ones. 

Second, illumination. I thought that they both have to have tell-tales associated with the switch, but they don't. They only need tell-tales 'somewhere'. Well, on the MX5 the hazard flasher actually triggers the left and right direction indicators which is a valid tell-tale for IVA. Similar with fog light, I've already incorporated a warning light into my dash lights so I don't actually need to do anything more. Obviously the correct colour and symbol has already been covered.

The only requirement now is that the switches are correctly labelled. At the moment I'm thinking of taking inspiration from my existing lights;

This is a set of seven inline. If I use the same design but aim for a '2x2' pattern, it means I could have the toggle switches in the bottom two, and them symbols in the top two. I wouldn't have the symbols looking the same as these, I'm possibly thinking white symbols on a black background would be best. What I'd do is print an inverted image on to acetate, then paint the back of the image with Tipp-ex to expose the white symbol.  

It does mean I still need to find some attractive toggle switches, which is actually proving to be quite challenging. It's not as if they need to be complex like on other cars, even the hazard switch is just a single pole to ground. The flasher unit deals with the complexity. 

And I do need to get some perspex or similar, that would allow me to finish the dash. I seem to remember hobbycraft do smaller sheets, the DIY places do panels suitable for greenhouses etc which are just too big. 

Tank surgery

 At the last car show in Newark, I bought myself a short length of fuel filler hose, just to finish off that particular job. Shouldn't be too much a problem I thought... then I got home and remembered how things sit;

Unfortunately the distance from the fuel cap location to the tank is longer than I remembered. It's also way too sharp an angle. And finally the roll bar support is in the way. Here's a better view of the issues;

Last night I had a thought about making a steel pipe to get from the tank to the filler location, but even that is not possible. So unfortunately it's going to be open surgery on the tank. Quite extensive open surgery in fact. What I did spot was a gap on the side;

There's a sufficiently large gap between the corner of the tank and the roll bar support. If I move the end piece to the side of the tank, it then becomes a shorter distance for the fuel filler pipe to travel. It's also a less severe angle to get to the filler, which means I can use the length of flexi filler pipe that I have bought.

The downside to that is I need to remove the end cap and the existing filler hole, and replace the lot with a repositioned hole. It's not going to come off without a fight so it's going to have to be a fresh piece of metal. And of course it's only thin steel to start with so that's going to be a fun task again. My wife described the tank as 'home made', and that's purely because of all the extra welds that had to be added to solve the pinprick holes! Still, I don't think any of that is a bad thing, I've got a lot more experience with welding so I might do a better job this time round. 

The last thing that is a worry is that I open up the end plate and find the tank is rusted to hell inside. This has been sat for many years, and in theory it's been sealed but water seems to find a way. Fingers crossed it's not too bad, but if not it'll be a whole new tank. I still have steel so it wouldn't cost anything other than time. I've got some 2 inch tube left over from my exhaust, it's not seamless but there's no requirement for seamless for a fuel tank. 

(Follow up from Wednesday)

So I got it cut open, and actually it's not too bad inside;

The surface corrosion is limited to the heat affected zone of the welds, and it is just surface corrosion. A wipe with a cloth gets rid of it. The edges are all rippled, but that's partly where it's welded and partly where I've taken the end cap off.

It looks really good after cleanup, the edges are pretty straight and I was able to make a template;

The lower half is the end plate with marks for folding into shape, then the top will cover the cutout section. It's marked up but more for riveting and welding.

Oh yeah, that's one thing. The metal seems to be 'pinging', IE it's going from one position to the next due to either tension or compression. That means that it's only straight in one state. So I'll need to hold it in place while I weld it. I'm thinking a series of temporary rivets will do the trick, then as I weld things into shape they will hold the surfaces together. 

I do need to insert the tube, which is the whole point of this exercise, but I also don't want to make things awkward when fitting the end plate. If I fit the tube before putting the cap on, I can get the weld done well but have a chance of warping the metal. Whereas if I cap it first then put the tube in, I can get things straighter than they were but the tube insert might then warp things. 

Either way I've got to be very careful here, I'd rather not have to go on the hunt for microscopic holes again. But I also don't want to blow through the metal as it's really thin. I might do some practice runs on spare tin just to see what I can drop the settings down to. 

(Thursdays update)

The cap is working quite well. The corners folded a lot better this time, I guess watching a whole load of random panel beating Youtube videos does actually improve things! This is the current state;

The sides are pretty tight although the plan for using some fixing rivets is still the best idea to really get things snug for welding. The tabs on each corner will be trimmed and then dressed round the tank, with rounded corners on all four sides I need to make a rounded cap. I've just noticed from this pic that I can see some paint underneath the new part, that'll have to be cleaned up before I weld. 

Talking of welding, this is my current welding setting;

So the toggle switch is at max, the rotary is at 2, and wire feed is at around 7. This works well for the steel I use, but is way overkill for this tank. Checking the manual it reckons 1mm to 1.2mm for these settings, given the fuel tank is 1mm I think that's wrong. I'm going to drop it to Max 1, with around 5 on the feed. That's good for 0.6mm to 0.8mm.

By the way, I think I might have mentioned this before, but these Clarke units are really good. While I started with an Aldi special, that burnt out after a year or so. This one I got second hand and had already lived a very long and hard life judging by the condition of it. A clean and replace of the consumables and it's alive again. The only real issue I have now is the wire feed knob, it has literally no resistance so it's really easy to knock it with the torch lead and set it too high or too low. I think a protective shroud might be useful, something to stop it turning by accident.

So the plan for tonight is to do the corners of the fuel tank, then the weekend will be welding it up and pressure testing it again. 

(Later that day)

The corners are now done;

I'm also happy with how the temporary rivet fixings are working. It's really able to clamp those surfaces together so I can get a good weld seam. Yes I have half a dozen extra holes to fill in, but that's easier than a potentially leaky seam. So that's all set up for welding, once I've had a bit of practice on some scrap. 

Wiring change of plan

 Ooh, a change of plan, I've not done that before... anyhow, I tried fitting the fuse boxes, but in the right location and using the existing brackets they end up looking like they're stuck in mid air. 

So I'm going to abandon the tabs and print some proper brackets. They'll get bonded on to the side and then they can be screwed down properly. 

A couple of other jobs have been done. First, the rear number place mount, looking massively overkill but really secure so no chance of failing IVA for it;

It looks good with the donor plate. I've also fitted the coolant bottle, although it needs a couple of nuts added inside the car;

And that's the last of the protective film too, whether that's good or bad I don't know. Perhaps after the second tube of metal polish I might rethink the whole aluminium look!!

Engine wiring part 2

 Rather unsurprisingly the engine wiring is still going on. It's really tough going, but if I get it wrong it's either a dead car before I start, or an AA callout on the way back from Malvern 2025.

The engine sensors are now cut to length, with the ECU mounted on the back of the firewall and nicely protected from the elements. I did think about putting it flat but it seemed like a waste of space. Then again, even sat on the firewall I can't put anything in front of it because I need to maintain access!!

The wires will all come across the bulkhead to the engine via a single location, so that will bind up quite well. The sensor wiring has been substantially shortened for the most part, the only one that is still factory length is the airflow sensor and that's because it's right out at front.

I've also picked up a few other sensors as I've gone. For example the cooling fan sensor is situated underneath the connector for the fuel injectors, so that got trimmed.

The next big job is actually what I thought would be the first, which is the 'big' wiring. I've got the alternator and starter motor already wired up as expected, because I didn't take them apart. But on the other end is the engine fuse box, and on the end of the other loom is the interior fuse box. Both mounted on to the chassis in the original car, so they've got mounting lugs. Problem is I can't seem to find a location where I can reuse the lugs. I don't want to use a different fuse box at the moment as it will just be that one extra complexity and cost. So I need to mount the two fuse boxes somehow.

The logical place would be above the steering column on the platform of the bulkhead, here's an earlier view with the body not in place;

However I wouldn't call it majorly structural, given that it's basically the same aluminium sheet bent out of the way and reformed, rather than having anything substantial added to it. I think to mount the two boxes I'm going to need some vertical mounting structure as well as some platform reinforcement. It does need to be off the surface, mainly because the wiring comes out the back of both. 

Putting them in place it actually looks like horizontal is better. The engine one can be horizontal, pointing out towards the engine. Then the interior one can be behind it, pointing to the left. That also means the wires to the ignition switch have a fairly short distance to travel, as does the main power feeds (blue and white/red). 

However the first job is to figure out the fuse layout. The engine sticker looks like it had fallen off as it was upside down compared to the box, and the interior fuse box has no lid! That's kind of expected, it would have been a dashboard panel rather than a lid. I wonder if I could design and print a lid, that would be ideal. 

Anyway, some random pictures;

The first picture of spaghetti would make any Italian cry, and the fact that it's a car loom in the midst of being chopped up would make any electrician cry! The second is the back of the front plug, with indicators, sidelights, dipped beam and main beam. 

Engine wiring

 There's no two ways about it, this is probably the biggest job remaining. The main loom is about two inches thick, and I reckon maybe half of it is redundant. More importantly it's designed to go down both sides of the engine bay, whereas I think I only need maybe one or two wires to go down the passenger side. In fact it may just be the O2 sensor on the manifold.

So the plan will be to take out each sensor individually, route them as required, shorten the wire if needed, then bundle them back up. I'm planning on doing this in stages, and I'll tick them off as I go;

Stage 1: High current

This includes;

• Starter motor. Partly complete as I left it in place.
• Alternator. Similarly partly complete.
• Ground to chassis. Big wire to be connected.
• Ignition switch. Done. 
• Fuse box. This is more about physically locating it in the right place.
• Battery. As above, getting it physically located and connected.

Stage 2: Engine sensors

This will include all of the following, traced out individually and then taped up once they're all complete. I'll need to put the ECU in place before I start here, as basically all of this connects to the ECU. Depending on what is required I might also need to put the fuse boxes in the relevant locations as well. 

• Igniter (C4) Now extracted. 
• White (to ignition coil)
• Brown/Yellow (to ECU)
• Blue (Ignition switch)
• Yellow/Blue (to ECU and to rev counter)
• Black/White (to ECU)
• Black (Ground)
• Brown (to ECU)
• Red (to ignition coil)
• Ignition coil (D4)
• Spark plug leads
• Red (to igniter)
• White (to igniter)
• Blue (to ignition switch and capacitor to ground)
• Main relay (E4)
• White/Green (Relay and main fuse block)
• White/Red (to ECU)
• Black (Ground)
• Black/White (Engine Fuse)
• Black/White (Cooling fan relay)
• Crank Angle Sensor (D7)
• Black/Light Green (Ground)
• White/Red (to ECU)
• White (to ECU)
• Yellow/Blue (to ECU)
• Throttle sensor (D7)
• Light Green/White (to ECU)
• Black/Light Green (Ground)
• Red (to ECU)
• Airflow meter (C7)
• Light Green/Red (to ECU)
• Red (to ECU)
• Black/Light Green (Shield/Ground) x 2?
• Red/Green (to ECU)
• Light Green (to fuel pump relay)
• Black (ground)
• Coolant temp sensor (B7)
• Blue/White (to ECU)
• Black/Light Green (Shield/Ground)
• Fuel injectors (B7)
• Yellow/Black (to ECU)
• Yellow (to ECU)
• White/Red (to ECU)
• Idle speed control valve (A7)
• Blue/Orange (to ECU)
• White/Red (to ECU)
• Purge solenoid valve (A7) I think this has been deleted?

Stage 3: Non-engine sensors and switches

• Fuel pump relay (C4)
• Blue/Red (to Fuel tank)
• Light Green (to AFM)
• White/Red (to ECU)
• Violet (ST SIGN FUSE?)
• Black (Ground)
• O2 sensor on exhaust (B7)
• Red/Blue (to ECU)
• Clutch Switch on pedal (E7)
• Brown/White (to ECU)
• Neutral switch on gearbox (E7)
• Brown/White (to ECU)
• Cooling fan via relay (E10)
• Yellow (to relay)
• Black (to Ground)
• Coolant thermostat (E9)
• Black/Green (to ECU and relay)
• Black (Ground)
• Horn and relay (C17)
• Green/Orange (to horn switch inside combination switch)
• White/Green (STOP FUSE)
• Green/Red (Horn)

Stage 3: Connection to steering column switch gear

Mainly lights and indicators, as the ignition switch will have already been wired in stage 1.

Stage 4: Connection to gauges and tell-tales

Once things have been wired from the controls and sensors it'll be fairly straightforward to wire them back to the dash. 

My circuit diagram

 This is going to be my reference for wiring, rather than a blog update. However it may be useful for some. 

I've split the wiring into parts, so I'll reference each part below.

Front lights

To be added...

Rear lights

Brake (Green)

Position/tail (Red/Black)

Reverse (Red/green)

Fog (Green/Yellow)

Left indicator (Green/Black)

Right indicator (Green/White)

Fuel pump (Blue/Red)

Black is earth going to two chassis points.

Gauges

1. Illumination positive (red).

2. Temperature gauge signal (blue/black).

3. Common ground to chassis (black).

4. Gauge positive (black/yellow).

5. Oil pressure signal (yellow/red).

6. Rev counter signal (yellow/blue). 

Tell tales

1. Side lights. (red)

2. Main beam. (Red/white)

3. Left indicator. (Green/black)

4. Common ground to chassis. (black)

5. Right indicator. (Green/white)

6. Fog light. (Green/yellow)

1. Battery positive. (Black/Yellow)

2. Brake fluid positive. (Black/Yellow)

3. Battery negative. (White/blue)

4. Brake fluid negative. (Blue/yellow)