More progress.

February 6th, 2014

After painting the frame last weekend this week my aim was to get it all seam sealed. I went and bought some sealer after work one evening. I use Sikaflex 221 which works very well. The good thing is it comes in black, white and grey. The grey almost matches the colour I painted the frame. You can paint over it so after it dries I gave it a quick spray from a rattle can.

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I only sealed the underside. I am not sure if I will seal inside the boot or not. I don’t really need to and it probably looks more correct without sealer. But it might be nice to have sealer there so if anything leaks it won’t get into the gap between the metal and the tubes. To be honest I am not sure anyone will notice either way!

I also spent some time working on a tachometer. I went through my left over MGB bits and found an old, 12 volt rev counter. I made a small circuit with a 555 timer to test it as well as hooking it up the the MG in order to make sure it worked. I took the guts out of the tach and mounted it in a piece of PVC downpipe as a housing. I machined up new face and end plates from aluminium on the lathe.  I spent some time drawing up a new face in Photoshop and I also removed the plastic 70s needle and bodged together the needle hub with an original old needle from a dead period speedometer I have. I had to carefully counter balance the needle by wrapping a few turns of solder to the short end of the needle. I was going to use the original old speedo housing but it was too vintage for this car so Joss found a more correct bezel in his box of bits. As it happens the PVC is a perfect slide fit into the bezel.

The original metal band that holds the glass in place was rusted away so I made a new space from another section of PVC. The face was printed on normal paper and glued to the front aluminium panel. I tested it all with my little test circuit. That just generated a square wave of varying frequency. For a 4 cylinder engine you need 33.33Hz for 1000RPM, 66.66Hz for 2000RPM, 100Hz for 3000RPM and so on. The frequency for a given RPM is:

Frequency in Hz = (RPM * 2)/60

The times 2 is because in a  four cylinder engine there are two sparks per revolution.

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Today was a holiday in NZ so I started looking at finishing off the edges of the floors. I needed to trim them so I can glue on the wooden edges. Unfortunately my jig saw decided to die. I’ve had it a while and when I took it apart I found it had just worn out. The gearbox was full of grease but non was around the gears. What was around them was a bunch of metal filings from the drive gear which had worn enough to stop engaging the jiggy mechanism.

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I was hoping to repair it, perhaps by removing the gear and turning it around so the unworn half was meshing but these things aren’t built to fix it seems and the gear is actually part of the motor shaft. So into the bin with the old Black and Decker and off to Bunnings for a new Makita. I try to buy decent tools now and I’ve found the Makita ones seems to last well. I stay away from any cheap brands. Black and Decker and especially Ryobi don’t last well and can’t be repaired. Definitely stay away from the unheard of brands unless you only very occasionally use the tool. The tool I use most is probably my angle grinder.

Bunnings always advertise that if you find something cheaper elsewhere they’ll beat the price by 15%. I often wondered if they really would. Today I found out. The other day I got a Toolshed catalogue in the post. They had a nice Makita jigsaw for $220. I looked up Bunnings online and they had the exact same one for $250. So off I pootled to Bunnings clutching my Toolshed catalogue and after some umming and erring they did honour their promise. So the jigsaw only cost me $186 in the end. It’s definitely nicer than my old one. Variable speed, oscillating action and much better built. It made short work of my floors!

I also got the router out and bevelled the edges of my floor supports, a little touch Joss suggested. I trimmed the front of them so they fit under the the front floor chassis mounts.

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Unfortunately all the wooden strips I cut some time ago to glue to the edges of the floors have warped into curves. And not the way I would have expected but they curved against the greater width. I have the clamped down to straighten them a little. It doesn’t really matter since the strips are much wider than the floors so the plan is to epoxy them on the trim it all to shape with the router.

To test this, and test the epoxy, I glued strips to the edges of the little wooden piece that makes up the floor of the battery box. The epoxy dries very fast but I have it all clamped in place. Tomorrow I will run the router across the edges using a flush bit with a ball end which should trim the edge strips to be flush with the plywood.

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Oh, the other thing I did last week is finally finish string wrapping the steering wheel. I had it half done then ran out of string so had to wait till I got more. I used a reversing knot where you wrap the string round then  back under itself as you reverse direction. This locks each turn in place. You have to pull really hard on the string each turn and I ended up with bad blisters on my hands. Some sort of glove is a wise idea!

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The string is far to clean and white so before sealing it all I am letting it get a bit more grubby and used looking. That’s not difficult to do just by touching it as I potter about the garage. It will get a nice filthy patina in no time!

One Response to “More progress.”

  1. Nigel Hamlin Wright Says:

    Nice work Simon, especially in the instrument face.

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