Hope the links here work as mere description is not enough - I would like to reproduce at small scale four of these column transition pieces, each with both corner and centre 'petals' as well as metal angular fillets between, and the Victorians really have me beaten. Maybe the only way is to carve a pattern and then cast them, in which case any guidance on lost wax/investment casting would be welcome - I can't see how they can be machined from solid.
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This is the only ornate part of the entire engine, so can hardly be ignored.
Look carefully at the way a Pozidriv screwdriver bit is machined for inspiration. Then machine the petals using either CNC or a jig to guide the milling table a la engraver. Attach the square top of the column as a separate piece.
Turn the column to the basic shape minus the red bits. Cast the details in soft solder or other low melting point material and glue them on. Once painted nobody will know how you need it.
Carve one by hand in whatever material you fancy, stick it onto a blank of the main column profile. Make a mould from dental mouding material (latex?). Cast them individually in resin or whatever from the mould. Glue into place.
Thanks for your input guys. As much of it needs a brass finish, then I want to make those part in brass. Sadly I don't have a 4 axis CNC machine - which is a good thing as I doubt I could operate one - but I can see it would be handy to have a dividing head for my newly acquired milling machine, so this might be the job that forces me to knock one up using a spindle and lathe gears (its been on my to do list). I think I will have to make these in three parts - the 8 petals and square top in brass, the middle section will be painted, so I can utilise some of your suggestions for low temperature casting or plastic moulding for that.
Thanks for the potentially useful link to the Prop Shop - their website is away being varnished at the moment, so I look forward to finding what they offer. I have a small muffle furnace that is good for 1000C, and I wondered if it might be possible to cast some in brass using a lost wax process (investment casting) - then just finish turn them. I suspect that the originals must have been made by casting and then finish turning - and I have always fancied doing a bit of casting, but I don't know how feasible it is. Anyone had any experience of this - (probably should look on a jewellery newsgroup).
Hi Steve, I did do some alu casting and that could well be the way to go. But then again you should make a model ...! Making patterns is very timeconsuming and rather difficult. Too much effort for only a few pieces. Depending of the scale I reckon handcarved selfcuring clay could be an option. Dirk
On Sun, 22 Jun 2008 04:01:21 -0500, IEB did e-scribe thusly...:
oops.... bad form to respond to ones own posts... please forgive... but 'Chesire Steve' ...if you do respond off-group don't use the btbroadband.com address (as above and on the original post), as stated elsewhere this morning I had to reset the PAN newsreader today and forgot to update the email address from it's default. That btbroadband account is not monitored.
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