{"id":1841,"date":"2019-08-11T17:12:22","date_gmt":"2019-08-11T17:12:22","guid":{"rendered":"http:\/\/ngtrains-com.stackstaging.com\/blog\/?p=1841"},"modified":"2020-10-31T12:37:30","modified_gmt":"2020-10-31T12:37:30","slug":"townsend-hook-update","status":"publish","type":"post","link":"https:\/\/ngtrains.com\/blog\/townsend-hook-update\/","title":{"rendered":"Townsend Hook Update"},"content":{"rendered":"

Apologies that this is a bit later than planned [see end of previous article for the reason].<\/span><\/em><\/p>\n

In the last episode I detailed how the new prototype castings were coming from two sources. One a complete CAD to brass package via Shapeways and the other printed waxes via Precision Wax and then on to C Harding Castings to be turned into brass bits.<\/p>\n

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Both have, in my opinion, produced acceptable results with some of the bits coming out better in different methods.<\/p>\n

This first image is the Shapeways collection which are a bit harder to photograph as they insist on coating the castings with a gloss coat as they seem to think everyone is doing shiny stuff.<\/p>\n

If I were building a model these could be used directly on it but this method is too expensive for supplying production – ie these cost more then the we’re charging for the kit.\"\"<\/a><\/p>\n

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This next group is the wax from one source, cast at another method. Some of these need some work before they can be used as patterns as they need the casting runners cleaning and altering.\u00a0 I have two set of these so I will be using one set to complete a model and finish the instructions.<\/p>\n

\"\"<\/a>I do have a dilemma though. I think I have decided what I am going to do but I will run it by you here just so that you know some of what is involved.<\/p>\n

Here we have the Salter Safety valve castings from the two methods. One of the risks with the wax route is that the waxes this process produces are very brittle (the ones i can print aren’t but we won’t go back to that just now) and both the examples were broken up and cast or broken as they came out of the ceramic mould and whilst they could be assembled to make a model they are pretty useless as a pattern. The complete one piece casting is the Shapeways example that has been lightly abraded in my grit blaster to take the shine off. This is how they should have all looked and how the waxes looked when I mailed them. I think the Shapeways part gets to to be the pattern for this bit!\u00a0 \u00a0I would make the observation here that the photos are cruel enlargements and that the actual parts are pushing the minimum thickness limits of the process.<\/span><\/em><\/p>\n

Now What<\/span><\/h4>\n

Probably by the time you read this the example of each part selected to be a pattern will have been cleaned, prepped and tested on a model to check the sizes and is probably on its way to the casting company. What they do now is: –<\/p>\n