Casting Thicknesses

At some time I will need to make a pattern for C.I castings. Now I realise that my question is a 'how long is a piece of string' type but I'm wondering if it will be possible.

The casting is 9" inches dia with 8 off webs around a 1 1/4" dia centre.

The webs need to be 3/16" thick. Will that work or do I need to look at fabrication?

Brian

3/16" should be OK in iron, have you got a sketch of the actual part ?

If the webs are cast they will have to have a draft angle for withdrawing the pattern, they cannot be parallel.

Paul.

Cast Iron (or Alloy Steel) castings can be made with the lost wax process.

This process will allow castings to be made with no draft as the pattern is not physically withdrawn from the mould, it is melted out.

These days 3D printing can be used to create a pattern direct from a CAD drawing, from a low melting point plastic that is melted out of the casting before the pour. Once the design is done 1 to 1 scale it is a simple matter to scale the size of the part with the cad program.

Link

**LINK**

Regards

John

Many thanks for the replies.

Jason, I'll sort out a drawing and send it to you, your comments and help are very much appreciated.

Brian

Look forward to seeing the actual item.

In the mean time I have just dusted these off which I think are similar to what you describe, they are the two parts that make up the winding drum for a 2" Superba Ploughing engine and are about 12" dia. The webs are all cleanly cast with a very slight draft angle and I would say 5/32" thick on average.

The alternative would be to get them laser cut or mill them yourself from steel sheet and stick them together a bit like the one at the bottom of this page

Edited By JasonB on 18/08/2018 14:02:25

Those casting look very good Jason. Many thanks for your time on this.

I've managed to do a rough drawing of my project which is a hind wheel for a Fowell-Box patent traction engine (when I finish my Burrell-Boydell).

I made one of these some years ago and still have all my hand done drawings but I want to make this new one in 1 1/2 inch scale.

Regards, Brian

Its amazing how much information is in a drawing. At first I imagined something like the cooling fins on an air cooled petrol engine. (it is said that a drawing is worth 1000 words).

Paul.

Looks to be something that can be cast but finding a foundry to do a good job of it will be more of a challenge.

Thanks Jason, the original castings forr my 3" version were done by a fairly local company called Canlin Castings and they recommended Meehanite for the material.They had a retired moulder who only worked on Fridays to work on any 'odd' jobs and he was excellent.

I have emailed Canlin to see if they still do this type of work and await a ( hopefully) favourable answer.

I'll let you know how it goes although there is probably another couple of years work on my Burrell to finish it and then there is the patternmaking!

This picture shows all the patterns used on the 3" version.

Brian

I've just checked with Canlin Castings and they still do 'one-offs' so I'll need to start patternmaking in between finishing my Burrell-Boydell!

Brian

If it is any help, most of the castings on my 7" scale Fowler lorry have been done by Specialist Castings of Denny. I was very please with the result - not cheap, but electric furnace and all the fine control that goes with such technology - not a single hard spot or chilled edge and all machined like continuous cast bar.

Martin

Molten iron is incredibly fluid. If you worry about casting thin sections, have you ever seen how thick a Victorian cast iron bath is?

Neil

Neil, that's a very good point, not only are the baths thin but they are thin over a much larger area than anything I need to cast.

I intend going up to the foundry to discuss patterns; the patterns in the photo were for 3" and I know they had problems with the gears, especially the one with 3 gears on the same pattern. I shall make those separate on the 1 1/2" version.

Brian

Thanks Martin for your suggestion but now I know that Canlin Castings will still do this type of work, I shall go with them again. The last batch that they did for me were excellent castings in all ways and they also cast some items in brass as well as the foundation ring and firehole ring in bronze.

Brian