jma1009
Elder Statesman
Posts: 5,901
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Post by jma1009 on Oct 9, 2015 22:12:23 GMT
hi hayden,
the pattern looks very good. my initial thought was that the curve on the spokes wasnt enough, but ive checked Boyd's 'Talyllyn Railway' which has the drawings of the slate wagon wheels and you have got the curve perfect and in accordance with John M Lloyd's excellent drawings in the above book.
cheers, julian
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Post by steamcoal on Oct 10, 2015 9:09:56 GMT
Julian, You just made my day! Tomorrow I will start to see the results when I begin casting. Is that book you refer to still in print? Hayden
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Post by ejparrott on Oct 10, 2015 9:18:13 GMT
I think it is, certainly still on the shelf at Tywyn I'm sure!
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Post by steamcoal on Oct 10, 2015 14:13:42 GMT
Good read is it?
Might try Mr Amazon
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mbrown
Elder Statesman
Posts: 1,720
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Post by mbrown on Oct 10, 2015 14:32:29 GMT
Boyd's book is a great read - especially if you are into the minutiae of TR history. But in recent years further research has shown that Boyd was pretty cavalier about some of the facts - he often accepted anecdotes without cross-checking and sometimes seems to have made up, or imagined, some aspects of the story. Recent articles in Talyllyn News cover some of this. On the other hand, the book is fantastic for the range of pre-reservation photos - it makes you really understand what the railway, and the area, were like as late as 1950.... The drawings of stock are OK but not always spot on - I can't comment on the curve of the wagon wheel spokes!
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Post by steamcoal on Oct 12, 2015 10:43:08 GMT
The first reproductions of the wagon wheels are coming out of the mould. The first casting was with encapsulating resin but there was too much shrinkage (4-5%) which created a stippled finish on the outer rim surface. The interior was good but too much work was required to make the casting good. The resin took sometime to cure and I was not happy. Next try was West System Resin 105 and Hardener which is shown in the examples below. each casting used 50mls of mixed resin stirred and poured into the centre of the mould to fill the rim via the spokes. Not many air bubbles and the finish is a gold honey semi transparent colour. Poured at 9:30pm and removed at 7:45 am or about ten hours to harden. original on right, second reproduction in centre and another casting just poured on left. Close up of finished item.Surface definition is very good and exactly like the original, even including the fingerprints and scratches. We walked across the road to ask the foundry if we were all OK and how many patterns we can fit on the casting plate. Answer is eight which is exactly what I need as a multiple of 40 total. This is most economic with 5 pouring sessions. The original outside dimension of the rim was 85.50mm and the finished dimension of the resin casting is 84.50mm. A shrinkage of 0.98%.
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Post by steamcoal on Oct 12, 2015 11:08:25 GMT
This is the prototype I am working to as best I can. There is not a lot of material in the wheels,in the spokes or the treads.The flanges are quite wide but to thin for rough handling and prone to chipping in my opinion. These are the spacers between the wooden rails. three sizes and I would,like to cast them in lead to add weight to the already light wooden frame wagon.There is an M4 hole in each one for threaded rod. Just have to work out how to cast them with a hole in the centre! Any suggestions anyone? longest one is 27mm x 10mm dia. 26 of them per wagon.
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neil
Active Member
Posts: 39
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Post by neil on Oct 12, 2015 19:30:47 GMT
Just as an update. I have now got my wheel design cast. I hope I have understood how to add images This is the first back from the casting company, it is cast in EN8 steel, from a wax, which I hand pored into a silicon mould, which I made from a 3D printed model. I guess it is a long way round to get a cast wheel. After the 3D print, I did have to clean up and paint, to fill in the imperfections from the printing, then it took me three attempts to get a dood wax, due to sinks etc in the wax. But I now have a slate truck wheel, it has been an interesting and learning period. Neil
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neil
Active Member
Posts: 39
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Post by neil on Oct 12, 2015 19:32:44 GMT
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Post by steamcoal on Oct 19, 2015 9:25:15 GMT
The progress of the last few days. Warm weather helps. I have completed resin casting the eight patterns and will now paint and prepare them for mounting on the pattern plate, 8 up at a time.
The colour variation was due to a new batch of hardner but usual curing time before release from the mould was ten hours.
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Post by steamcoal on Nov 21, 2018 9:33:50 GMT
Today I have the fruits of my labour, and my bank account is a little depleted. There was a knock at the door and I was delivered a box of bright cast slate wagon wheels, and a very expensive casting box from the foundry across the road. Following the protracked effort of making the patterns, casting them and further procrastination of forking out more than a few dollars to ready them for metal casting, I must say I am happy with the end result. So here we have an 8 up casting box and sixteen fresh Dinorwic curved spoke slate wagon wheels.
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Post by steamcoal on Nov 21, 2018 9:38:54 GMT
Julian,
Just looking back to the 2015 post when you queried the spoke curve, I hope it looks right. Too late now.
I suppose I better build the wooden part now :-)
Hayden
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