3-D Printing

Surely there is no point in having a 3D printer if you can't do 3D CAD

Rod

You might well think that (I'd probably agree). However, other options being promoted by some 3D printer companies include

1. 3D Scan - then print from scan.

2. Download 3D files from internet, then print. Files from web are either purchased or shared freely.

Also worth noting that 3D Printer companies are at the forefront of providing low cost 3D CAD tools of various types. Some of these are not 'CAD' as we might think of it (e.g. Cubify Sculpt)

You are not wrong

It's one reason that I'm trying to get up to speed but life keeps getting in the way.

Fortunately at the moment a lot of what I want to do includes gears and Gearotic will spit an STL file out for 3D printing without having to draw the gear in 3D

Also depends what you mean by 3D CAD

I've got a small 3d printer and use OpenSCAD for what little I have done - is a different approach well suited to mathematicians or software engineers but doesn't require any traditional CAD skills.

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Anyone ??

The reason I ask is ... I know that the Wax is specially formulated to melt out, and then burn out, leaving almost no residue. But it seems reasonable to assume that melted PLA will not run like molten wax, and burnt PLA might leave some ash residue within the cavity.

Does any forum member have actual experience of using printed PLA as a substitute for the "proper" Wax ?

... Grateful for any advice.

MichaelG.

Thanks Jason

That's a useful start

... some discussion here

MichaelG.

High temperature seems to be the answer, as in this link:

**LINK**

Regards,

Andrew

Why would you make patterns instead of subbing out and having the parts made directly? - As Andrew, I also have used the subbys to make parts (finished and ready to go into assemblies) and if I want metal I would have them printed in metal - for those not aware, the search term you need is DMLS (direct metal laser sintering) and if you add the term "rapid prototype" it should take you to something of interest.

I would also agree with the comments about needing some file creating method, the only method that is likely to suit a model maker/experimenter is individual 3D cad and this is going to be hard to support in the magazine given the software costs and range of choice. Logically, this would be the place to start.

The way it seems to me, even though this is fast evolving new tech, there is little point making something that has limited ability (other than making simple models covered in stringy afterbirth) unless it is for the benefit of understanding the origins of the technology or for some fun. It seems to make more sense to concentrate on more "generally" usefully items to do with the conventional machines we mostly have. An example being the rotary laser thing that popped up recently. There will always be new ideas that you can cobble a prototype machine for (die sinkers and wire edm have all been done of late) but these are very special items suited to only a few people. As I get older, things that help me use conventional machines are getting more important, especially compensating for degrading eye sight!

On reflection, perhaps the reprap fitted with a mig torch might prove more interesting (although I would get some real ear ache about the electricity bill....)

Mark

Edited By John Stevenson on 14/02/2014 00:13:18

I recall a dental technician friend of mine showing me a rather nice metal Polo Mint he'd made using the lost wax process which is what is used for casting dentures. Not sure what metal he'd used (after the passage of much time!) . When I remarked that Polo Mints don't melt as easily as wax and presumably result in residues, he said they simply used higher temperatures and left it in for longer. Presumably this is enough to oxidise any carbon that forms. Sure enough, it was a very clean part.

Murray

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Andrew,

Thanks for that very useful link.

MichaelG.

And hear is another example.

Les.

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Short answer, Mark

Where's the fun in that ?

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Slightly longer answer:

I enjoy tinkering with Microscopes, Clocks, Cameras, etc. ... Repair, Restoration, Modification, or sometimes just pulling things apart to find out how they work ... This is a hobby.

Many of the Microscope parts were originally made from Investment Castings, in Brass/Bronze or in Aluminium Alloy. Inevitably; items get acquired with parts missing, worn, or damaged ... or I might want to make a special part.

I doubt if I shall ever have the luxury of my own Foundry; so I must draw the "subcontract" line at pouring metal ... but I am interested in doing as much of the other work as I can.

We are being encouraged to take 3D Printing seriously, and that is exactly what I am attempting to do; but I don't want to make finished items in plastic [be it ABS or PLA] ... I am, however, keen to learn how to best use 3D printing for pattern-making.

I hope that explains my personal interest in this topic; 'though I fully accept that others may be differently motivated.

MichaelG.

Thanks Murray

Thanks Les

I have an old ME with an article on casting from lost wax patterns and using other things, such as beetle and leaves, as the patterns for jewellery. The principle being to get the mould really hot and keep it that way. The technique also involved using a wet asbestos pad to create steam to force the metal, melted in the mouth of the mould) (usually silver in this case) into the detail.Another method I have read about is whirling the mould around one's head on a string. Both methods sound decidedly risky to me.

Neil

Hi Neil,

Definitely getting and keeping the mould very hot for pattern bakeout and during pour is important in lost wax casting, certainly any of the times I have witnessed pouring in an investment casting foundry for industrial work the moulds were visibly at orange/white heat before pouring. A shield of flame from a gas burner was used on some pours directly over the pouring gate to minimize any oxidation of the melt as it was poured and afterward as the gates and sprues cooled. Some sort of grey powders were also sprinkled on the gates and flamed up after pouring.

As to the asbestos, steam, and whirling moulds filled with hot metal, I would stay away from those items myself if doing any casting....

Cheers JD

Depends what you are casting, in what and how big, I do centrifical tin casting using a Centricast machine in rubber moulds, very safe and easy process. The machine is a very easy project to make in a SHED. But you need to make a few identical bits to be worthwhile. Moulds are 10" or 7" diameter.

Alloy casting is now a low cost deal, there are several good furnace designs made from cement and cat litter on the web. Some people do lost plastic using plastic foam bits stuck together to produce oversize castings that can be machined down e.g. www.buildyouridea.com. Often the plastic foam is shaped with a hot wire cutter, all very suitable for real model engineers at home in their SHEDS. Mike Cox has some very well written projects on his excellent web site **LINK**. There is also the very good video series by "Myfordboy" on the tube that covers home casting.

Billy,

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Neil,

Back in the days of M.A.P. Model Engineer published an excellent little booklet

I bought mine in 1977, and I think it was still available [in the same editition] from MyHobbyStore until quite recently ... May be time for an updated version ?

MichaelG.

Edited By Michael Gilligan on 14/02/2014 19:46:51

For the centrifugal casting technique, there is a safer approach using a spring loaded rotary arm with the mould on the end. I've seen it done commercially by a dental laboratory, complete with guards around the whole affair. Not impossible to build one at home. Another technique uses a vacuum pump to suck the air out through the porous bottom of the mould. The flask is just a piece of metal tube with the refractory mould cast into it, the metal is poured into the top and the vacuum is applied to the bottom...much nicer than messing around with water near molten metal.

My own thinking on 3D printers is that I would be better to take my 3D model file to someone that has the right gear and get them to print it. This is the approach that I have taken with colour printing too, having found that whenever you want to use it, the jets are clogged and the cartridge goes dry while you try to clean it. It is much cheaper to let someone else do the prints, and because of economies of scale they will have better gear than I can afford. I suspect this will also apply with 3D printing.

John

HERETIC,

Now how are we going to make excuses up to buy new toys ?

Says John S leaning with his cup of coffee against a 3' square x 4' hight all singing, all dancing colour A3 laser printer with 4 paper trays.Which cost less than the average service on an Audi