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WW1 Thornycroft restoration


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In regards to your core boxes.... been there done that!

 

I found the simplest way was to make male masters than use those to cast the actual core box in plaster-of-paris.

 

Thanks Terry. I knew I should have asked you first! I am well on the way carving them out at the moment but should I give up in disgust, I will try this method.

 

Thanks for reminding me!

 

Steve :)

 

PS. Looking forward to hearing your engine too!

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Father has been busy and I forgot to mention it! The front cover from the differential housing was missing so I made up a pattern and Dad had it cast.

 

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He has now machined it up including a felt seal groove and it is ready for the paint shop and fitting.

 

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One more down!

 

Steve :)

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It is interesting that you should ask that one Andy, as Barry has just very kindly printed the patterns for the silencer ends for us. This is an original, photographed many years ago.

 

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And these are the patterns and core boxes.

 

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They are super objects and will do the job nicely. However, their surfaces have a definite texture to them which will allow the sand to get a 'key' and make them difficult to remove. Barry recommends 'Pattern Coat' ( http://www.easycomposites.co.uk/#!/patterns-moulds-and-tooling/pattern-making/composite-pattern-coat-primer.html ) which he applied to the throttle quadrant to such good effect. It builds well and with a rub down took out the printing lines nicely. Father has just bought some and I will have a go with it shortly.

 

Steve :)

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I However, their surfaces have a definite texture to them which will allow the sand to get a 'key' and make them difficult to remove. Barry recommends 'Pattern Coat' ( http://www.easycomposites.co.uk/#!/patterns-moulds-and-tooling/pattern-making/composite-pattern-coat-primer.html ) which he applied to the throttle quadrant to such good effect. It builds well and with a rub down took out the printing lines nicely. Father has just bought some and I will have a go with it shortly.

 

I keep meaning to get some of that. I am actually printing patterns at the moment (machine tool parts) and I have been using "knifing putty" to fill the texture to good effect. It comes under a variety of names (Spat-o-Rapid is one, and Halfords sell a variant. My current tube is https://www.spraygunsdirect.co.uk/3m-acryl-red-glazing-putty-409g.html#sthash.0Cf4Xyk0.dpbs which makes it sound likr something for holding windows in)

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We have done a bit more this weekend in the shape of the silencer and fuel tank. I went to the railway on Sunday where I was able to use a nice set of bending rolls. I had previously cut a piece of steel for the silencer (from a bit found in the garage, hence the surface rust!) and the rollers soon made short work of it.

 

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I just need to rivet the seam now.

 

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Next job was to bend the fuel tank. My good friend Adrian had very kindly cut me a piece of zintec sheet (zinc plated steel) to the right shape and I had spent some time marking the beginning and the end of each bend with a black felt pen. This proved to be a very valuable action. Now, the first bend was too tight for the rollers but, as I have previously posted, I made a bending jig with a piece of scaffold tube and some timber. This worked remarkably well.

 

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Then into the rollers. Actually, I was so intent on the job that I forgot to take a pic of the first bend but this is the second. We fed the sheet through the rolls almost to the line and then wound the rear roll up as far as it would go. The rolls were a perfect size for this job so at that point, we turned the handle a little until the other line went between the rolls before taking of the pressure and pulling the sheet out.

 

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A trial fit with the aid of some toolmakers clamps looked very promising so we put it back for the final bend which was done the same way.

 

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We had to have a couple of goes at it to get it in the right place but then Adrian and Matt tried the clamps again.

 

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It all looks very nice.

 

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Now all I have to do is drill 200 holes in it, tin it and rivet it all together!

 

Many thanks to Adrian and Matt for making a job which really concerned me remarkably easy. You need your friends in this hobby!

 

Steve :)

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Steve,

 

Would the silencer tube be a straight overlap or would the edge not have joggled to achieve a smooth round external appearance?

 

Are you going to remove the Zintec coating from the edges of the petrol tank sheet before you attempt to solder it all together?

 

Barry.

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To be honest, Barry, I am not sure how the silencer was put together. I cut the steel to allow the ends to be hooked in opposite directions to interlock but that is looking difficult to do and I am told that it would be unlikely at this period. I am thinking along the lines of a straightforward lap joint with rivets but, now that you mention it, the end could have been joggled to give a circular interior. I may have to make a tool to do it. Further thought required!

 

In the fuel tank, I shall just clean the steel before tinning and not worry about the zinc. It will solder well enough, I am sure. I will tin both sides of each joint before closing the rivets and then simply warm it with the gas torch and feed in a bit more solder if necessary. The proper stuff made of lead this time!

 

Steve :)

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I have been told to put the sheet into the rollers diagonally along both diagonals before rolling the final curve, this would break the straight ends. Haven't tried it yet but it makes sense to me.

 

Regards

Marcel

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Hi heres some shots of the muffler from our 1924 bb4 q it was complete when recovered note that the clamping rod is 1 Mt long but may not be original its been awhile the ends are handed the rear the fish-plate is inserted and held with a split pin looks right the other end has a machined shoulder that would go into pipe and be clamped note the three studs in each end holding a baffle from memory there were two pipes pierced and opened at opposite ends held together with more baffles hole lot was hanging under left rear of engine sub frame by i think brass clamps and wing nuts the use of wing nuts on this truck all ways got me like on the top of gearbox and diff b

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Edited by brockwood
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I have started dismantling my M4 engine in preparation for freeing it up. Two things I have found exceedingly challenging: one is that the heads of all bolts or nuts are dead size for size with my Whitworth spanners - there must have been an earlier standard than what I am accustomed to; the other is that every fastener is dead tight, and even when successfully loosened, the thread depth makes them very tight to undo - perhaps another earlier standard.

Have others shared this experience?

And another problem that adds to the difficulty - many nuts are so close to the casting that the corners bump when undoing them. A socket or ring spanner therefore cannot be used, so it is down to an open ended spanner which runs a greater risk of damaging the nuts.

ian

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I have started dismantling my M4 engine in preparation for freeing it up. Two things I have found exceedingly challenging: one is that the heads of all bolts or nuts are dead size for size with my Whitworth spanners - there must have been an earlier standard than what I am accustomed to; the other is that every fastener is dead tight, and even when successfully loosened, the thread depth makes them very tight to undo - perhaps another earlier standard.

Have others shared this experience?

And another problem that adds to the difficulty - many nuts are so close to the casting that the corners bump when undoing them. A socket or ring spanner therefore cannot be used, so it is down to an open ended spanner which runs a greater risk of damaging the nuts.

ian

 

Sounds pretty par for the course. Having hexes that tightly fit the spanners is good news though, and gives you a lot better chance of getting them out! Our engine spent ten years on a stand being regularly squirted with penetrating oil. That helped no end. Ten years is excessive and six months would probably have almost as much effect. Heat on a nut has an amazing loosening effect too and, failing that, the application of a cold chisel is a very good way of getting things moving, especially with heavily corroded nuts.

 

We have always found that most of the stiffness is due to corrosion products and a good wire brushing of a bolt or a run through with a tap generally frees them up.

 

Hours of fun ahead. Good luck!

 

Steve :)

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Since John so very kindly loaned me the front water elbow to use as a pattern, I have been making up a core box to match it. First job was to measure up the casting and I did this by drawing around it on my drawing board using a couple of blocks to hold it horizontal and then a square to transfer the profile onto the paper. Once I had a drawing, I could transfer the profile to two blocks of MDF.

 

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I dowelled them together and then planed them to the profile transferred from my drawing.

 

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I had been puzzling over how to generate the centre holes but found that Screwfix offer an adjustable drill. I set this to 2 1/4" diameter and then had a tes run in a piece of scrap. This went well.

 

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I then took my blocks and marked out the centre lines of the casting. Note that the blocks are over-size to allow some space for the core prints.

 

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I transferred the centre lines by the age-old method of sticking a scriber through the drawing and joining the dots.

 

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Then I placed the block on the cross slide of the lathe only to discover 'the deliberate mistake'.

 

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The block was too thick for the drill to align with the split line!

 

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I remedied this by planing one of the blocks to a thinner section and was then able to dog the blocks down.

 

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I used my magnetic base as a datum to get the centre lines aligned with the axis of the lathe and then proceeded to drill my holes.

 

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Once split, it all looked very promising. I then drew in the profiles of the bores.

 

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To help my accuracy, I cut a template from a piece of mild steel.

 

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Then I started to work it out with a gouge. I soon got bored using this one and ground one of my larger lathe tools to do the job instead. Much quicker!

 

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I tidied the bore out using the Dremel with a sanding drum and a piece of glass paper.

 

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Then it was on to the other bit.

 

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This worked out OK.

 

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Now I have to do it all over again for the other side!

 

Steve :)

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And then there were two!

 

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The next bit was the wide flare in the tube where it sits on top of the cylinder block. I couldn't fit this earlier due to the centre height limit of the lathe so I glued up another block and then drilled it through to create the radii.

 

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A few moments with the band saw and some glass paper finished it off.

 

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The slot is wider than the thickness of the original blocks so I glued an extra strip on each side before tracing the end profile.

 

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Then it was more work with the gouge followed by a clean-up with the dremel and sanding drum.

 

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The blocks were glued on and left with a weight to hold them down. The paper is to stop the two halves from sticking together.

 

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A tidy up with some glass paper and it is off to the paintshop.

 

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Now I need to add pieces to the original casting to create core prints.

 

Steve :)

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Next job was to bend the fuel tank. My good friend Adrian had very kindly cut me a piece of zintec sheet (zinc plated steel)

 

Are you concerned about the compatibility of zinc with modern petrol (containing ethanol)?

 

The ethanol absorbs water and also decomposes fairly rapidly, resulting in a reduced pH (making the solution acidic) in tanks where the fuel is not frequently changed. Zinc is rapidly consumed in acidic environments.

 

I guess there is less than 50 grams of zinc exposed to the petrol and the majority will probably only result in sediment.

 

Worst case could result in leaks at the soldered seams, but that may not be an issue if/when the zinc is alloyed with the solder.

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What about those off the shelf tank liner paints, can they be purchased in ethanol resistant types?

 

At least you wouldn't have to do the cleaning step as that is the most labour intensive part.

 

I used an Aussie competitor of PQR-15 on my Kettenkrad petrol tank. As you say, the cleaning process is intensive, but not

difficult. The hardest part is coming up with suitable bungs for the openings.

I am in Outback Oz and the issue I had was that the instructions assume a typical climate with typical humidity. This gives a working time of 15 to 20 minutes for the paint. As our humidity is so low, the paint stayed liquid for nearly an hour!

The problem there is you need to keep tumbling the tank until the paint is thickening otherwise it will run to the lowest point.

BUT, you need to empty it out before it goes so thick that it will no longer run.

 

To the best of my knowledge, it is resistant to almost anything you are likely to expose it to in everyday life.

 

Also, make sure you wear gloves and are careful with this stuff. If you get it anywhere you don't want it, you have a major problem.

As far as skin, I am told it is a case of waiting till that layer of skin sheds. It sticks to everything.

 

Regards

Doug

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Are you concerned about the compatibility of zinc with modern petrol (containing ethanol)?

 

 

 

Hi Ben.

 

I had not thought of that one although I know that modern fuel is evil stuff. Will it harm the running of the engine?

 

I seem to remember that there is a patented fuel additive which consists of zinc pellets in the fuel line but can't remember the name. It was supposedly supplied to the Russians during the war to put into the lend lease aircraft fuel tanks to help burn the local fuel.

 

I can't see it harming the joints as it will be in solid solution with the lead. Even then, the amount there will be tiny as by the time I have cleaned the surface for soldering, it will nearly all be gone. What about attacking the steel though? The poor old FWD has a welded steel tank but has been parked up for two years with half a tank full. Time we gave it an outing again.

 

Leaded fuel is just so much better!

 

Steve :)

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