BenHawkins
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Everything posted by BenHawkins
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When I was having MDF shapes CNC machined for patterns some time ago (for the 1914 Dennis) we managed to fit in a couple of profiles for the header tank into the sheet (but not a complete set for the pattern). I have quite a bit of MDF left over from the mock cab I built (also for the 1914 Dennis) so I have cuts some pieces out a little larger than the templates. After making a couple of aluminium top hat pillars to pass through them (tapped M6 to help extract the pattern from the sand) I glued a couple of them together on the table in my office (as that is reasonably flat and will not upset the glamorous assistant as much as doing it on the kitchen table). I then took them out into the yard and used some plastic strips (printed to the correct thickness) to offset the router cutter and make the second layer slightly larger than the first and give the pattern a sensible draft angle so it should pull from the sand. I need to repeat this several times before I can screw and glue the printed parts to them.
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I picked up a free sample bag of threaded inserts at a engineering trade show and have been using those in the back of smaller patterns. I decided to print little handles to fit to M4 set screws as well. The project is not so much of a rush that I need to get something printed every day so I am printing small items in the evening and get a couple of the larger parts at the weekend. I am using a relatively small layer height (0.15mm) and thick walls so could print faster with thicker layers.
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Yes, they were from Ben. I need to organise a trip to see the Fowler next time I have an excuse to be in that area.
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We refitted a lineshaft to our kitchen last weekend; currently it is just ornamental and there are no plans for a flat belt driven apple lathe or mixer but I like to keep option open.
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I have made a few BS190 bolts and slotted nuts to secure the steering box this week, once painted I will fit them. So far I do not have the confidence to leave the 3D printer going when I am out of the house but some more of the radiator pattern parts are finished. I need to get the router out to shape the bits of MDF but we hired a skip this week so I have been moving large rocks and soil and every opportunity. Three of the water connections between the cylinder blocks are corroded away or broken. I made a CAD model of the pattern and core box. The pattern took around 13 hours to print, the core box will take about double that.
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The pig was a test print. I think the castings, tube plates and tube will cost more coins than it can hold.
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This week I purchased a set of patterns for the Austin generating set cylinder blocks. These blocks were also used on the early (1910-1912) Austin 10hp car. There is frost damage to my blocks but they are probably repairable (as the engine runs I doubt they are cracked through to the bores). It seemed too good an opportunity to pass up and they are a great example of pattern making. Front half of the cylinder block. There are lots of core prints for the cylinders and water jacket. Note the loose pieces to make up the flange held in place with bent nails. The sand will be built up over the loose pieces and the nails removed before the box is completely filled; otherwise an additional core box would be required for this feature. The back side of the cylinder block. If both sides were the same this one would not be required. This core box makes up the cylinder bore, valve ports and combustion head. These two make up the core boxes for the water jacket. No sand goes on the green prints; which shows where the two loose pieces go; note the small loose piece at the bottom left of the upper box. These cores would be challenging to pack and quite fragile when completed so must have taken a skilled moulder. They came from a foundry in Kings Heath when it closed some decades ago so could be the originals used to make my engine. I thought other people who have resorted to making their own patterns could learn a lot from these! If anyone wants a dummy generator we could cast some blocks for mounting on a wooden crankcase (or make all the other parts if you like a real challenge).
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Thanks, I missed this at the time you posted it. Another interesting project.
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There is still some detailing to do on the gearbox before I can consider making any more parts. I have decided that the priority tasks should be getting the steering and handbrake linked up to make it easier and safer to roll the chassis in and out of the garage. The top of the steering box needs to be fixed to the dash. Although I started fitting the dash over a decade ago I left it 2" tall and didn't finish the dash irons as most other commercial vehicle engines would sit higher in the chassis. Now the project has the correct engine (thanks to Hedd and Ken!) I was able to finish the dash irons to the correct height by warming them up and bending them to match the original drawing (it is great how many of these have survived). I then trimmed the bulkhead and cut the opening for the flywheel. Once the 14 holes were marked up and drilled I sorted out 5/16 BSW coach bolts and modified them in the usual Dennis way (filed three corners off the coach bolts and filed one corner into each hole in the dash. The radiator pattern making stalled around 6 years ago for the same uncertainty about engine fitment. I have no drawings for these parts, just an idea of the overall dimensions and some cross sectional drawings of the Hallford horizontal tube radiator that also appears to have been supplied by Coventry Motor Fittings. I also have plenty of photos and these have also been very helpful. On my 1914 Dennis the radiator flanges match the flange size on the White and Poppe engine so I have used the same for this design and also match the tie rod mounting detail. I have purchased one of the cheapest 3D printers to help work through the long list of patterns for this and other projects; it only has a 220mm x 220mm bed but can still do a lot of the detail work. It is a horizontal tube radiator mounted on shackles. These features seem to have been in fashion for a year or so either side of 1908 before the vertical tube radiators mounted on trunnions became standard.
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The later gearboxes are stub tooth 5dp 20 degree pressure angle. The original was 6dp 14.5 degree pressure angle; shafts, covers etc. are all different but I may be able to use some of the transmission brake parts.
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The ratchet detail is one of the drawings that survives. The tip angle of the pawl is 77 degrees and therefore I expected them to lock in when the hub is being driven.
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I have a couple of 1920s Dennis gearboxes I could fit but I would prefer to put the correct version in. It is probably too much to hope that the correct gearbox will turn up so my only option will be to manufacture one. I don't like the idea of paying someone to have all the fun even if I was able afford it. I have made a few of the simple components already but it is certainly going to be a challenging project.
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We have been tidying the garage so we can get back into this project soon. I have been working through the information I have found on the gearbox and started to model it in CAD. There are 39 parts listed in the catalogue but there are no diagrams and it does not list things like bolts, keys and taper pins. Drawings have survived for 14 of the components; this includes the four shafts but does not include the selector rods or gears. Much of this detail can be guessed at from the drawings in the patent. One of the novel features is the freewheel mechanism. What force do you think the springs need to apply to the pawls to make it work reliably?
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We decided to have afternoon tea with the working vehicles to celebrate VE day; this was the second drive for the 1908 Singer but as it is only 15 metres between the garages it really needs a run out on the road to get a better idea of the performance. Tinkering has continued on the Dennis and we have added a felt seal to the back of the fan pulley as it leaked a fair bit of oil. If a road test shows it to be relatively leak free I can swap the modern belts over to Whittle belts. I have also found a Powell and Hanmer self generating headlamp (as shown in the in-service photo) but it needs a clean up before fitting. The correct size of tan canvas sheet was available off the shelf but I can't get a good photo of it in the garage and I probably need to improve the way I have tied it down. As these three are moving from rebuild into the tinkering/maintenance phase I am starting to think about the project plan for the 1908 Dennis.
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I have blasted the ironwork and really liked how the blacksmith tidied up the corner by forge welding a triangular piece in. They have cleaned up well. Repairing the threads that have been cut off will have to wait for a later date. I briefly looked at how much it would cost to reproduce the body in oak as used originally. Some shopping around will certainly be required.
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This project has been on hold for too long, we hope to restart it later this year. The current project is a 1908 Singer (I could not come up with even a tenuous link to military for that one). I had one of the wheels rebuilt by an excellent wheelwright; he brought me a present for this Dennis along with the Singer wheel. Back in 1976 he rescued a dilapidated horse van that appears to have been identical to those used by Carter Paterson and as originally repurposed to the body for this 1908 Dennis project. The four parts are (top to bottom): 1. Shore Staff 2. Timber Standard 3. Tilt Hoop Iron 4. Outrave Stay I offered them up to the chassis and they look to be of the correct proportions so will be perfect to scale the body from. He does not remember using any of the other parts to repair any other waggon so they are probably in the spares stock somewhere. I am now really looking forward to another visit to the wheelwright during the summer to hopefully collect a boot full of other rusty treasure.
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I have photos on the day it left the factory and one in service and none of them show anywhere to tie ropes.
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In order to rectify a slight coolant leak I removed the water pump to add more gland packing. Whilst the coolant was drained and the pump was off I machined a boss, silver soldered it to the coolant pipe that feeds the cylinders, then drilled through and tapped it 1/4" BSP for a tap. This was in preparation for providing water heating to the carburettor.
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Thanks for the kind comments about this project. Looking at your lovely photo of KT665 it is a very similar age of lorry and could either be identical to mine or possibly the 30cwt version. The three ton did not have the offset in the front axle (outboard of the springs) so the chassis was a few inches higher up. Coincidentally I have been building a machine on this slightly lighter road rail trailer recently so the concept is not completely dead. The two ton lorry was fitted with 720mm wheels for 100mm wide tyres. I have include a PDF of the tyres to show the dimensions. Twin tyres were fitted to the rear. The chassis is made from 4" channel for the main rails, parallel along their length; back at the start of this project you will be able to see photos; the outside faces of the channel are 37-3/4" apart. There is a channel front cross member and a tubular member at the rear. An additional 3" channel frame is suspended below the main chassis to carry the engine and gearbox; this is pivoted at the front. It is 11'4" wheelbase and 5' track, the chassis overhang at the back was adjusted to suit the body style. Mine is shorter than typical at 15'6"; this does have certain advantages as far as garaging is concerned! I guess you don't need much space to get to two tons when you load with fruit and vegetables. What software do you use for your 3D CAD? I might be able to provide STEP files for some of the components, for example it should have this type of White and Poppe cylinder block (rather than the pair cast Aster I have fitted as the nearest equivalent). I would love to see your finished model. tyre.pdf
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Steering column detail showing worm and nut steering box. A selection of parts. Many of these I have, but it is good to have detail of the front cross member. Bonnet rest etc. And finally the radiator, this appears to show that I have the correct radiator. Although pretty good this parts book still appears to miss quite a few parts such as the exhaust silencer. Period literature described the T4 as a "J type in miniature"; although this might be true for the chassis construction there are many differences in the rest of the vehicle. At least we have a better idea of what all the missing parts should look like and therefore stand a chance of identifying them.
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Front Axle. At least I have most of these parts. I think this shape of axle cap (Part number 55312) is only seen on the T4 Thornycroft. The back axle built up in three layers is another feature that seems unique to the T4. A sliding block rear universal joint is used. I am missing this but as it is similar to the one I made on the 1914 Dennis at least I have had some practice. Brake drums and blocks.
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Gearbox. The N/S and O/S gearbox mountings look identical in the photo but have different part numbers. And quite a few parts to go inside the gearbox. Footbrake components And some of the parts on the outside of the gearbox
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And for me, this is where is gets most interesting. Parts diagram showing the cylinder block with fixed head and inlet over exhaust valve arrangement. Crankshaft, camshaft, oil pump etc. Oil pipes, magneto couplings etc. Flywheel, clutch etc. This does not show the fan blades on the flywheel (visible on earlier photo).
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Flywheel, clutch and universal joints. Gearbox, steering gear and brakes. Care of the back axle Side view of chassis
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Some good pictures of the T4 engine; perhaps somebody has one in their shed. Further information on the engine and some good views of the crankcase. A little information on fault finding A good view of the steering column detail, fuel tank and oil indicator.