Hello, I would appreciate if subscribers could suggest the best method for creating a muold to replate the profiles as shown upon the attached noting the thickness of the plate and that it has a rebate of half the thickness. Thanks in Advance
You could sand cast it with the part line along the flange lip. Depending on which side was the show face it could be done in the same orientation as on you drawing or flipped over. Flipping it over would be easier as you would have all the sand weight in the drag and could make the cope shallower less weight to lift. need to add some taper to the outer flange lip to get it to pull cleanly... might have to do the same to the vertical wall of your rebate as well. With the sizes listed shrinkage is goin to be an issue so plan for that (depending on the alloy used). If they need some surfaces machined you'll need to add material to those areas. But that's a whole lot bigger of casting than I've ever poured. I don't have a good idea on the size or layout of the gates and runners. None of my gear is built to pour that volume of material.
Are there 3D isometric images available for the part? Showing these might give those posting ideas a leg up on generating their images.
Honestly a little more information on what it's for would help as well. The folks around here are happy to help other caster figure things out. But we've had some folks drop by and think we'll design the molds for their production run so they can save money. That's the not cool part. If it's a production run fine but work with one of the folks here that can do that work and come to a fair agreement. if this is someone rebuilding an old green house, steam train, widget that's out of production because it's a passion project. Great! You'll find that being open and honest about the project will get you more constructive feedback. I'm out of my depth with a casting of this size so I'm not going to post a drawings.... I honestly don't know where to start past the basics I originally. But we don't know your skill level. I just guessed.
A thousand apologies for late reply, personal issues have impacted me. I have attached four images to the above earlier post. The objective being to assist in the restoration of a railway dining carriage dating back to 1894. I am keen to understand how the patterns could be optimised for moulding, hence the post.
All the usual casting rules apply... draft, risering, radius and filleting. You would want to feed that thin section well so it doesn't chill shut when pouring. What is the metal you are casting? Looks like there will be lots of machining anyway, so it would almost be better if you could cast it as a uniform thickness then hog out the rebate with a mill/shaper. You will want the chequer/words to be in the drag (bottom half of mould) then it's a pretty straight forward parting.
Many thanks for the advice, initially I am considering aluminium as a prover material. Apologies for my lack on knowledge, however perhaps you could clarify the term 'chill shut'? In terms of the rebate, I had though about forming a mound in the cope if that is a practice that could be used?
"Chill shut" refers to the metal solidifying before it completely fills the mold, resulting in an incomplete casting. It's something that needs to be taken into consideration when designing the gating system for castings that have large thin sections.
Your gating and risering will be different between alloy and, presumably iron, but yes, always good to have a practice! If the you can make the parting line where the thickness changes, then no mound to form. I don't think you would have much luck forming a mound on the cope, it will be rammed differently and liable to break away. A proven casting method is "coping down" which could also possibly work. It's certainly an interesting challenge, someone's obviously solved it before!
