BenHawkins
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Everything posted by BenHawkins
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No progress on this project has ever been quick. In order to punch out the radiator gills I needed somewhere to set up the fly press I had been donated and better space for ironwork would needed for the body ironwork. So, at the start of the COVID lockdowns we started clearing a raised bed at the bottom of the garden so we could build a blacksmiths shop. There are a few finishing touches required but it is now a useful new space for making things. I had purchased a couple of sheets of 0.010" tinplate so we were able to test the tooling made by Andy Pugh. The glamorous assistant and I found a rate of about 600 gills per hour was quite therapeutic. And after a few short sessions this week we have in excess of 1250 gills. This is around 10% of what is needed for this radiator. We have used about 60% of the material I have but the sheet is a little bit awkward to handle. It looks like I will be able to get 108mm wide coil which will fit four rows and be cheaper than the sheet. However, I need to wait until another coil is being split to this size before I can obtain any. I tried mounting a few gills on a copper tube with some (13 year out of date) lead-free solder paste and heated it up with a hot air gun (paint stripping type). Although much better than using a propane flame I still overheated and discoloured the gills. I tried again in an oven, no discoloration and the gills were certainly fixed in place but still room for improvement. I will try it again with some new paste.
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I have been donated a Zenith 30K carburettor (via team Gosling) that I would like to try on this engine. This is of the "triple diffuser" type and I hope it will give better performance than the single jet Claudel Hobson. Most of it came apart reasonably easily once I made the special tools for the job. The exception to this is the lower plunger in the corrector. It is made of steel and so far has remained stuck solid. The corrector is the device with the second lever, I don't really know what it does but found it on a diagram (in French). Can anyone help with further information on this model?
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Some companies will apply the rubber to a loose band, others will insist that they are mounted. Certainly putting the wooden wheel through the autoclave for the vulcanisation process will destroy it. I have led Steven down the wrong track with the wheels for ED-810, that has the lighter weight axle (used on 30cwt lorries). He appears to have the rear axle used on two and three ton lorries with larger hubs. It should all become clear as he dismantles what remains of the wheels.
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Back in 2005 a friend of mine found a late 1920s Dennis chassis in Kent (I was in no position to take on a project at that point). It did not find a home but was broken up and virtually all the parts distributed across the country to help restoration projects. Unusually the chassis still had the petrol tank mounted but after all these years it turns out it did not fit the intended project so was offered to me. The body layout drawings in the 1908 catalogue give the dimensions as 15"x9-1/2"x3'6" - exactly the size of this one. It has the Snercold patent filler described in the catalogues too. Snercold was the trademark for the Safety Non-Explosive Reservoir Company
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More photos for comparison. A wide single front on a Dennis hub. It is possible a wider rim and tyre were fitted at some point. An "original" front. I just cleaned it up and painted it. New 100 for 720 tyre. It was necessary to press the tyre onto the rim with canvas between to get sufficient tonnage. A professionally rebuilt front. All new timber with original hub and steel rim. Some of the timber that was replaced. Note the felloes are approximately the width of the tyre fitted. The heat shrunk rim is usually wider. In addition to protecting the wood from kerb damage this is also essential for pressing on the tyres - you do not want to be applying the load to the timber. An "original" or at least not rebuilt rear. This is of much heavier construction than typically seen on a 3 ton lorry. Not the additional bracing band for the brake drum and how much wider the spokes are than the felloes. Heat shrunk rim protrudes on both sides of the wheel. Rebuilt wheel, this is a copy of what was removed but a different design to the other side. Note the spokes are much narrower. The "as found" spokes and felloes. On this vehicle twin 120 for 720 tyres were specified. Note the felloes are approximately 230mm wide. The new ones ended up slightly wider.
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After several checks of the dimensions I drilled the radiator side tank castings for the mounting holes and then tried fitting it to the chassis. There is still some adjustment to be done and some more checks before drilling the tube plates.
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I am not sure how much use the dimensions from LE9588 will help. Although a similar model yours is actually a heavier weight version. LE9588 has a similar back axle but runs on single rear tyres; the rear springs only have shackles at the rear; yours have shackles front and rear and the axle alignment is constrained by locomotive style horn brackets (not present on LE9588). I believe according to the build sheets they were "860x90" (front and rear) tyres on the LFB pumps for 1911. I am pretty certain these are Avon tyre sizes, so the 860 refers to outside diameter rather than band size. I suspect the band size is 720 but can't be certain. Although later, a better match for your wheels is probably ED-810 (owned by a member of this forum). The engine picture you posted is an earlier version (probably 1907/08) but pretty similar. By 1911 the serpentine water connections had been dispensed with and the connections were made between the cylinders at the centre line. I hope the works production order for your chassis survives as it should answer most of the questions and I will finally be able to give you some definitive answers. The archive is once again welcoming visitors but I imagine there are still restrictions in place and as you know this made our last visit less productive than usual. Five hours of driving for a couple of documents (ordered in advance) means we have to continue with other projects at the moment.
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Thanks Barry, I was keen to avoid the UV exposure and developing stage of the process so gave the toner transfer a go. There is a light box I can borrow but it is too small for the tread plates. I might give the dry film a go for the ID plate on the 1908 Dennis; that one is a slightly different design and it is always fun to try another method.
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I would like to thank everyone for their support of this project. I know it does not completely fit the military theme of the forum but hope that it has been of interest and useful to other people attempting similar restorations. To answer the question about etching, the toner protects those areas from the ferric chloride. I obviously didn't get it perfectly adhered as there was some shallow etching behind the toner (simulated patina?) Following the etching I cut the identity plate out and painted it black. Fine silicon carbide paper stuck to the back of my steel rule was used to polish it back to reveal the raised areas before stamping the numbers. Two of the fields are left blank; I will stamp them if I ever find out the correct numbers (when new). I believe both numbers were a little bit below 800 from surviving Works Production Orders. The number is on the axle somewhere but obviously I don't have the original gearbox. Six weeks ago I did the artwork for the tread plate and sent it off for manufacture. I am lucky because the original drawing survives, it could have been made from that but I didn't want to pay someone else to have the fun. There are plenty of etching services available to do this sort of thing but I wanted some for both of my Dennis vehicles with a deep etch and someone who could deal with a CAD format (such as DXF) rather than a Corel EPS. Originally I tried some steam model people but ended up using a machine nameplate company in Scotland. They worked out at £27 each (delivered) and their production line laser cuts the profile and does the blacking and flatting back. All that was left to do was countersink the holes and screw it down! So that is two ways to get the job done. The tread plate is bigger than the transfer paper so would have been more difficult for me to do, also I wanted a few of them so was able to split the cost of the mask they have to produce. I am running out of things to make for this vehicle; it's been fun and hopefully we can get it out a bit more in the near future - the speedometer calibration needs testing!
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I have been working through the "finishing touches". Originally there was a small brass plate fastened above the bonnet carrying the vehicle details. These survive on other preserved Dennis vehicles and I had taken measurements and rubbings in the past. Using Computer Aided Design I was able to generate the artwork and print it onto some "press-n-peel" film. This is basically a plastic film with an emulsion on one side. It has to be printed on a laser printer; apparently some brands of toner work better than others. The artwork has to be a mirror image of what you want to retain when etching and you have to make sure you print onto the matt side with the emulsion (the CP&Co asset tags are for the other projects). The brass plate needs to be free of all contaminants; this was a piece of polished brass that had been protected with a plastic film so there was no need to clean it back. With the brass on a wooden board and using the "garage projects" iron the brass was warmed up (being protected with a sheet of paper). The blue film was then placed on the brass, toner side down with the sheet of paper on top and given a further ironing. The instructions warned not to press too hard or the edges might smudge. The instructions then said quench in water and peel off the film. Not quite the result I wanted. Second attempt, ironing for longer with more pressure. Some of the artwork was rectified with a marker pen and I inked in the back so it would not be etched. It was then immersed in ferric chloride for a couple of hours. Finally it was washed under running water.
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Thanks Doc, CP&Co bought several batches from Dennis and I think I now have photos of every batch but the one mine was in (end of 1908). They did not have Dennis bodies fitted so there were no factory photos taken, originally I thought the motor vans were used in central London, but the picture of the Addlestone district probably suggests that they were used where properties were further apart.
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I decided to stitch a leather belt for the speedometer drive. This started with a hole pattern and scribing lines as described in a lathe manual. Then stitching in-situ with waxed twine. And finally putting it in place. To make the speedo cable I turned up some brass ends and soldered them on to some 1/2" brass flexible conduit I purchased at an autojumble. Steel ends were turned up for the inner and crimped on by placing them in a vee block and punching it down with a centre punch. That is another thing to test when lockdown ends. I have a speedometer app on my phone to check I got the maths right.
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I found this picture of the odometer used on the early Thornycroft BT. It appears to have a plate that swings over the number to protect them.
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We have been digging trenches and mixing concrete this week so I have been looking through old magazines when I need a rest. This is a 1906 notice from Carter Paterson advertising their investment in speedy motors. And some Dennis vans in Addlestone, these ones were built in 1911. They still have the horizontal tube radiator but mounted on trunnions rather than shackles.
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Dennis must still be busy as they cannot supply me a replacement gearbox. Their standard answer is they sold the last one yesterday!
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Thanks Andy, I will dig out the original factory drawing and annotate it for the new diameter, or is a new fangled step file better?
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I have finished machining the speedo drive parts and fitted them to the lorry. The next jobs are making the flat drive belt and flexible drive shaft. The tensioning spring is a bit too long and weak but it should be easy to sort a replacement.
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Yes, 24 years old and 210k miles. Might consider it run in before too long.
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ProFormance Metals have been very helpful and supplied the 8swg tube very quickly at a reasonable price. I have made new bolts and castellated nuts to complete the set for the ball joints. The ball on the drop arm is a good fit in one of the sockets. The other socket is a rattling fit on both balls (slightly worse on the one in the photo which is a little worn). I will check what other balls I have in stock but expect to end up making an oversize ball.
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I have been a bit distracted this week, the weather has been good so I did some trench digging for the smithy and repointed approximately 20m2 of brickwork (long overdue). One of the modern cars needed some work for the annual MOT test (perhaps modern is the wrong term as our everyday cars average over 20 years old), but I did manage to machine the coupling for the speedo drive. The speedo cables were threaded 3/4x26tpi and the drive I am copying had the bracket threaded 1-1/6x26tpi.
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I don't remember seeing anything on early J types/L4 engines during my visits to the archives but I will go through what I have and see if there is anything relevant (I tend to photograph everything I can, if permitted). Visiting archives in the UK has been nearly impossible for a year due to the Covid situation; hopefully access will improve later in 2021. I have more Thornycroft stuff to go through so I might turn something up. For one of my other projects I put in a request to the Toyota museum in Japan earlier this week; they responded within 24 hours having taken 20 photos of a vehicle for me - Japanese efficiency.
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Sorry, yes 8swg does appear to be available. Not through my usual suppliers so I will have to shop around.
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For the drag link I had expected the braze to be holding the tube in place fairly well. However as I machined off the tube it became obvious that there was quite a bit of clearance between the original 1-1/4x10swg tube and the forgings. As I turned down the diameter of the tube it started to tear so I peeled it off. The braze was only at the very end. I believe the first end was as it left the factory, the second end had been repositioned as part of the trailer conversion. For this end I used an angle grinder to thin the tube on both sides and then peeled it back. The braze had penetrated a little deeper on this end. With the tube removed it exposed a series of holes and chisel marks from the last time it was removed. In this photo I have already welded back on the 3/16" thick piece I cut off the end during disassembly. I then filled in the holes and grooves with some more weld. Initially I had just intended to silver solder the ends into some new 1-1/4" x 10swg tube. However the tube I have been able to purchase is on the bottom limit of thickness so the inside diameter measures 1.025" and once I have cleaned the forgings back they are around 0.975" diameter. Such a gap is a bit wide to expect capillary action to draw the alloy into the gap. Something to think about as there are plenty of things to be getting on with before I need steering. Suggestions welcome.
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Thanks for the suggestions, I think the face is celluloid. I am much more at ease with metals and not sure if pigments in wax might transfer into the face Some time ago I cheaply purchased a pocket watch holder, it was missing the majority of the insides but still had the velvet in the front section so I purchased some more to match. One turned up on eBay recently so I was able to see how the cushions should look. There is an outer ring of wood that is fastened in place with two wood screws; covered this with wadding before fitting the felt and then stitched a small circular cushion to fit in the middle. Then there was the simple job of fitting it in the cab.
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It is a 30mph Smiths speedometer. I purchased it at the Banfield auction right at the end of the first day. The auctioneer really wanted to finish so ran through the final lots at a fast pace; I think this is the only reason I could afford it. The red 12mph speed limit is quite faded and I cannot decide whether to paint it back in. One of the things I really like about the speedo is the second pointer that records the maximum speed achieved. The rest button can be locked off with a lead tag. The owner of the lorry (Ernest Shentall) was a JP so I could well imagine him choosing this model so he could keep an eye on his drivers. After drilling and tapping the split pulley I mounted it up on the milling machine and bored it out to fit the propshaft. I clamped some packaging card between the two halves to make sure it would clamp at the nominal diameter. I skimmed a bar end of steel to the same diameter as the propshaft and clamped the pulley onto it. This may have been good enough for the turning forces but I decided to drill a radial hole in the steel and tapped the hole 1/4BSW, then fitted a screw so the pulley could not rotate on the shaft. I skimmed the belt surfaces and gave them a bit of a polish, just following the shape of the casting by eye. I also started machining the belt tensioner parts. The bearings are in the post; I will finish it when they arrive.