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cropwell
01-07-2016, 04:34 PM
Here is a link to a sketchup file on dropbox. https://www.dropbox.com/s/8zoxsmhqdrj72mx/stubasex.skp?dl=0

I am making a 3D printed model of a lamp base to use as a pattern for bronze casting. I draw it upside down as otherwise you have to print it with supports, which takes an age and uses a lot of plastic.

The bronze caster wants to have sloping sides so that the pattern pulls out of the sand mould easily, and I think it looks better than straight sides anyway

The problem I am having is that one side is not closing, and when I put the model to Makerbot, it becomes two open sides.

It is doing my head in !!!!

Cheers,

Rob

Clive S
01-07-2016, 05:40 PM
Hi Rob I am sorry that I can not help you with a Sketchup file but I might be able to help to redraw it in SW and send you the appropriate file. (if it is not too complicated)

cropwell
01-07-2016, 05:48 PM
Thanks for the offer, but the design only exists in the virtual space between my ears. I have a feeling that the answer is simple, like a guide line or point being in the wrong place, so the four points of a quadrilateral don't form a flat plane.

I have almost resigned myself to a complete redraw, using different guide lines and points.

Cheers,

Rob

cropwell
01-07-2016, 07:43 PM
I think the problem was that the guidelines were not on the same plane. I redrew the thing and it seems OK now. I just have 16 hours of print time before I can see what it is like as a pattern for casting.

Cheers,

Rob

Neale
01-07-2016, 09:09 PM
Rob - are you going to use the printed pattern direct from printer or finish it first? I could imagine that the pattern won't release too well from the mould if it is not smooth enough but finishing printed parts is a bit fiddly - machining a casting is easier in my book!.

cropwell
01-07-2016, 09:23 PM
Rob - are you going to use the printed pattern direct from printer or finish it first? I could imagine that the pattern won't release too well from the mould if it is not smooth enough but finishing printed parts is a bit fiddly - machining a casting is easier in my book!.
It will get a bit of sanding, then a wash with Methyl Ethyl Ketone. The design has sloping sides to make it easier to mould in sand.

Have a look at http://www.stuartakroydglass.com/new-designs/?galAlbum=44

Stuart and I are developing a version of this glass sculpture with a lighted base. Stu has had a prototype base machined in steel and was not happy with the look of it, so we are trying the cast bronze route.

If it turns out well the castings come out at 30 each, which is a more favourable price than the machined steel version and we think they will look much better.

Cheers,

Rob

cropwell
02-07-2016, 10:25 AM
Another technique I am experimenting with is to make a solution of scrap ABS plastic in Methyl Ethyl Ketone (I call it 'Dip' after wtaching Who Killed Roger Rabbit) and use this to 'paint' the surface to flow out the printed surface, which is always textured from printing. This project is more Art than Engineering.

Rob