IAN_B Posted November 20, 2017 Share Posted November 20, 2017 I think the key is "getting the hang of it". Despite looking at a few Onshape tutorial videos, to an amateur who has never even used 2-D CAD (was a draftsman in the early 60's!), the learning curve looks mighty daunting. It's probably better to keep looking for original parts than to try and draw them up for 3-D printing of patterns, or simply use the parts from which to cast copies. Ian Quote Link to comment Share on other sites More sharing options...
andypugh Posted November 20, 2017 Share Posted November 20, 2017 7 hours ago, IAN_B said: I think the key is "getting the hang of it". Despite looking at a few Onshape tutorial videos, to an amateur who has never even used 2-D CAD (was a draftsman in the early 60's!), the learning curve looks mighty daunting. I will try to keep this brief as it is rather off-topic, but as someone who did technical drawing at school in the 70s but never used it, and then went on to do 3D CAD as a job I might have some perspective. Don't think about 3D CAD as making a drawing so much as making the part. In fact it can sometimes be helpful to design the parts exactly as they would be machined. The fundamental operations in 3D CAD are revolve (lathe-like) and extrude (mill-like). Unlike with a real machine tool you have the choice of adding or subtracting material, rather than just removing. Usefully for making foundry patterns you can add a taper to the extrude operations for pattern draught. (The CAD tools also tend to have tools for adding draught to faces for this reason, but these tools might not always be able to "solve" the geometry) With engineering CAD you mainly use a dimensioned / constrained sketch as the basis of the operations (this is not the case in animation or flowing-shape product design). You can constrain lines to be tangent to each other or at right-angles etc, which is nice because the computer does a lot of the "solving" of the shape for you. If I was modelling the spider I would first draw a sketch of half the cross section of the rotationally symmetric part, then revolve it to get a plain funnel. I would then create another sketch plane on the open end, sketch a couple of circles linked by arcs, (dimensioned from the centre of the funnel) and extrude-cut that to make one hole, then pattern that x3 rotationally. The bosses would start from a sketch plane offset from the end of the funnel by the 1" dimension, again a circle dimensioned from the centre, and with a construction line from the previous hole to give an angular constraint. Extrude the correct distance and another rotational pattern. Then run round all the edges with the fillet tools to finish. It's literally 10 minutes work. Probably 45 minutes if you are getting the dimensions from a part rather than a sketch or table. Quote Link to comment Share on other sites More sharing options...
flandersflyer Posted November 20, 2017 Share Posted November 20, 2017 On 19/11/2017 at 10:20 AM, Old Bill said: Thanks for that Barry. I hadn't heard of that software so I must give it a try. Always something new to learn! The bonnet is on order but we won't see it until the Spring now. In the mean time, Dad has made up the bonnet catches. They are a slightly odd arrangement as the pegs are mounted on curved brass strips. These do give a handhold for lifting the bonnet but are really too small as I can only just get two ungloved fingers behind them. Never mind. That is how Thornycrofts did it! Dad curved the strips by putting them through our small bench rollers until they matched his template. They were then clamped in the jig and the ends bent over to match. The rivet holes were drilled. The pegs were turned up and silver soldered in place before cleaning up and a final polish. They have since been painted green, as per prototype! Steve Your producing good work Steve... Carry on Quote Link to comment Share on other sites More sharing options...
flandersflyer Posted November 20, 2017 Share Posted November 20, 2017 On 08/11/2017 at 5:01 PM, andypugh said: Braze repairs are quite common with cast-iron parts, which is why I suggested silver-solder. I don't think that the following is the solution here, but I have also had good results repairing the arm of a mechanical hacksaw using stainless-steel MIG wire. The reason to use stainless is that it won't turn into a super-hard martensite due to carbon migration from the cast iron. I guess that bronze MIG wire might be even better. It's the grade though 216 and 218 are I think supposed to be a good one Quote Link to comment Share on other sites More sharing options...
Asciidv Posted November 21, 2017 Share Posted November 21, 2017 Whilst Steve is surrounded by MDFdust as the last of the patterns emerge can we have another slight diversion? There has been discussion about repairing the broken cast iron part by brazing. Can anyone report success on cast iron using a MIG welder loaded with brazing wire? Alternatively do you think using a TiG torch with the current wound right down using a braze filler rod is a better bet? Or do you do it the traditional way and bring everything up to temperature very slowly, weld, then muffle and let everything cool down very slowly. Or I suppose the final option is to bite the bullet and just send the part to Slinden Services or Cast Iron Welding Services and have it done by experts? Quote Link to comment Share on other sites More sharing options...
andypugh Posted November 21, 2017 Share Posted November 21, 2017 1 hour ago, Asciidv said: Can anyone report success on cast iron using a MIG welder loaded with brazing wire? No, but I am really enthusiastic for you to try it and report back :-) Quote Link to comment Share on other sites More sharing options...
Asciidv Posted November 21, 2017 Share Posted November 21, 2017 O.K. Andy, if no one else replies I will spend my £27 on ebay and buy a spool of MIG brazing wire. Quote Link to comment Share on other sites More sharing options...
Old Bill Posted November 22, 2017 Share Posted November 22, 2017 I shall look forward to hearing your results with interest, Barry! As you mentioned, I have been making MDF dust again. Horrible stuff but it does the job. First job was the core box to go with the propshaft spider pattern so kindly printed for me. This is to put the centre hole in at 2 1/2" dia and save us a lot of metal and machining tme. Step one, glue up some blocks. Clamp to the cross-slide and drill through. The block now has a parallel hole. However, the core prints have tapered ends to locate the core better when assembling the mould. To achieve that, I bored out some blocks with a tapered hole and then stuck them onto the ends of the MDF. The timber I picked up for the blocks was an old piece of beech which I had to plane square first. A lovely piece of wood but hard as hell! Mind you, it did bore through beautifully with a glass like finish straight off the tool. They were glued on to the ends and then the whole lot was squared up on the sander. My usual two coats of Bondaprime polished with wire wool and pattern 26 is complete and ready for the foundry next week. Onto the next pattern..... Quote Link to comment Share on other sites More sharing options...
Old Bill Posted November 22, 2017 Share Posted November 22, 2017 The next pattern is the last one for the water system in the shape of the water return spigot on the back of the radiator. Another damn fool shap that won't sit flat on the bench! I started off by putting a piece of oak in my splendid new wood turning lathe and turning a cylinder. I then cut it into slices in the chop saw with it set to 3 1/2 ° These were glued up and a flange and core prints added to the ends. After a good rub down to hide the lobster-tail effect, ribs and filler were added and it was ready for painting. This core box, whilst simple was hard work. I started out by drilling the straight sections in the lathe again. Then, I painstakingly worked it out with gouges and glasspaper using a cardboard template to get the curve. All very tedious. Then I had to do it again! All successful in the end and finished off with Bondaprime. That is number 27 so only three left to do! Dad is off to the foundry again next week. Next report won't be patterns! Steve 2 Quote Link to comment Share on other sites More sharing options...
Tomo.T Posted November 23, 2017 Share Posted November 23, 2017 Steve, It's all fascinating including the patterns ! More power to your elbow. Tomo Quote Link to comment Share on other sites More sharing options...
nz2 Posted November 23, 2017 Share Posted November 23, 2017 Sorry to disappoint you but that fitting for the top tank is wrong. On the two Thornycroft J radiators I have ( in poor condition) both have short inlet pipes extending only about 75 mm from the header tank. Again one of those odd variations we have picked up, whether it be a change in design over the years or could it be as a separate part of a larger diameter for colonial use. The pipes here are 75mm long and 70mm od. How does this compare to the one you have made? Doug Quote Link to comment Share on other sites More sharing options...
Old Bill Posted November 23, 2017 Share Posted November 23, 2017 I don't think we are very far off with the water return and there is certainly at least one lorry with an identical component! This one is Steve Pettifer's J and is the very first one in which I had a ride. His casting does not seem to curve down so far and may be a little shorter than ours. The outside diameter is 2 3/4" so this one looks to be about 8" long. The pattern I have made is 10" so I may be a bit generous but there is an easy solution if there is a problem. This one is the charabanc at Sandy Bay near Exmouth and has a low-level radiator. This casting is noticeably shorter. Are your radiators high or low level types as that may account for the difference? Isn't it amazing that with the hundreds of photos I have, I have almost none of this casting! The only other clue I have is the parts book and, if anything, this one looks longer than mine. To be honest, I don't think we are that far off but time will tell when we try to fit it and get it in line with the casting on top of the block. Incidentally, I have just realised that we have, between us, made every single component on this page. Madness! Steve 1 Quote Link to comment Share on other sites More sharing options...
IAN_B Posted November 23, 2017 Share Posted November 23, 2017 Just checked spigot on the radiator I have, and it is like the sandy bay photo shown, about 7 1/2" long (rough measurement against my hand) and not nearly as curved. Ian Quote Link to comment Share on other sites More sharing options...
Old Bill Posted November 23, 2017 Share Posted November 23, 2017 (edited) Interesting! Is yours a low level or high level radiator? Steve Edited November 23, 2017 by Old Bill Quote Link to comment Share on other sites More sharing options...
nz2 Posted November 23, 2017 Share Posted November 23, 2017 13 minutes ago, Old Bill said: Interesting! Is yours a low level or high level radiator? Steve Knew I would get a bite! I'll go out and photograph the casting later so we can compare. My parts book copy (1919) shows the same long unit. If we could locate an earlier and also a later parts book many of these riddles would be answered. Doug Quote Link to comment Share on other sites More sharing options...
IAN_B Posted November 24, 2017 Share Posted November 24, 2017 6 hours ago, Old Bill said: Interesting! Is yours a low level or high level radiator? Steve It's a low level radiator, with the crank passing through the bottom of the core. Ian Quote Link to comment Share on other sites More sharing options...
nz2 Posted November 24, 2017 Share Posted November 24, 2017 The two radiators both have the crank through the lower tank. Truncheon mounts are on the sides , not on the bottom tank. then again could these be for a model JJ or even a Q? Again lacking a parts manual of the type and time. While not the best of photos to show this particular part an indication of its shortness can be seen. Doug Quote Link to comment Share on other sites More sharing options...
Minesweeper Posted November 24, 2017 Share Posted November 24, 2017 Quite a different shape from the "J" high level radiator - I would say that your Radiator is from a totally different model! Quote Link to comment Share on other sites More sharing options...
IAN_B Posted November 24, 2017 Share Posted November 24, 2017 Here is a photo of my radiator (I have two and both are the same). The mounts are on the side plates. Ian Quote Link to comment Share on other sites More sharing options...
nz2 Posted November 24, 2017 Share Posted November 24, 2017 The bottom tank design in the photo is similar that shown in the X model parts book, being curved. Also shown is the curved lower radiator outlet.and the recessed areas for the bonnet supports on the top tank. However it would appear this design was also used on latter J models, but from when is the question. All the parts I have are from different vehicles and nothing as a complete identity to work as a basis point. I need an earlier version of a radiator as well for the early J, which has no Thornycroft name cast on the top tank. Photos show the name was cast on a separate curved plate and screwed in place Doug Quote Link to comment Share on other sites More sharing options...
nz2 Posted November 24, 2017 Share Posted November 24, 2017 Found another photo of the other radiator, this time showing a better indication of the shortness of the top tank inlet. Quote Link to comment Share on other sites More sharing options...
Minesweeper Posted November 24, 2017 Share Posted November 24, 2017 Again, not a Subsidy "J"! I will be interested to know what it is when you manage to identify it! Quote Link to comment Share on other sites More sharing options...
nz2 Posted November 24, 2017 Share Posted November 24, 2017 2 hours ago, Minesweeper said: Again, not a Subsidy "J"! I will be interested to know what it is when you manage to identify it! The question becomes what is actually a subsidy radiator? Is it only a J radiator having the mounts placed on the bottom tank? Looking through photos of J's in military service some have mounts on the bottom tanks, and the crank passing under the bottom tank. Other images dated 1917 show mounts on the sides with crank passing through the core. Others images show side mounts with crank underneath. This point of confusion is further shown with images of early J's with the non cast name on the top tank having the crank under the tank and another with the crank through the bottom tank. The overall result appears to be a period of modification and change took place regularly. From each of the photos we have posted what is shown is the change that occurred over the years of J and on to related models production. Having dated Ian's two chassis, that assists in setting a time line for the the sequence of radiator shape to production time . That is assuming these are the same as new on the vehicle and not replacements that are upgrades. Accidents etc could well mean a replacement radiator had slight variations to the original. One of Ian's chassis is a X model, yet we have two identical radiators. Looking closely at the style of castings about the edges of the core, with Ian's style having two bolts for the curved sections bolted to the tanks, those I have have three bolts. Ian's have the crank through the core, mine are through the bottom tank. It is confusing, so restoration will be at best one of making a judgment as to what appears to be correct. Quote Link to comment Share on other sites More sharing options...
Old Bill Posted November 24, 2017 Share Posted November 24, 2017 It was part of the Subvention Scheme requirements that the radiator be mounted entirely above the chassis. This does make it very high and give the longer return line to the top tank. Those mounted lower down with the handle through the core would have been civilian vehicles, most probably post-war. The lower position certainly improves the visibility for the driver and shortens the return line casting. The Thornycroft radiators all have a close family resemblance so I would suggest that the best way to determine the actual model from which any radiator comes is by measurement. The X-type was essentially a lightweight J so it could easily use the same radiator but I don't know for sure either way. Our radiator was cast using patterns made from the original radiator fitted to the Hampshire Museums 1916 J so I am content that it is the right one for ours. In general terms if the radiator has a curved bottom, then it is not a Subsidy radiator but it could still be a J-type rad. Steve Quote Link to comment Share on other sites More sharing options...
IAN_B Posted November 24, 2017 Share Posted November 24, 2017 (edited) 1 hour ago, nz2 said: Having dated Ian's two chassis, that assists in setting a time line for the the sequence of radiator shape to production time . That is assuming these are the same as new on the vehicle and not replacements that are upgrades. Accidents etc could well mean a replacement radiator had slight variations to the original. One of Ian's chassis is a X model, yet we have two identical radiators. Looking closely at the style of castings about the edges of the core, with Ian's style having two bolts for the curved sections bolted to the tanks, those I have have three bolts. Ian's have the crank through the core, mine are through the bottom tank. It is confusing, so restoration will be at best one of making a judgment as to what appears to be correct. One caution I would throw in is that there is no guarantee that the two radiators (or engines for that matter) actually belonged to the two chassis I have. I have what is essentially just a collection of bits gathered from a number of sources. Here is a photo of the X model taken at Maitland April 2016. I believe its radiator to be the same as my examples. The Top water pipe on this truck is very short - only 3" or so. Edited November 24, 2017 by IAN_B Added reference to top water pipe. Quote Link to comment Share on other sites More sharing options...
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