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Turning foam question

H

Hugh

Joined
May 6, 2004
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Location
Sonoma, CA
A little background and then the question.
In a past lifetime, I used to make stained glass lamps.....before I turned wood. In the time of Louis C. Tiffany - he used wood for lamp molds. Now they are mostly made from fiberglass.

I now want to make a lamp mold or more than one lamp mold of my own. I was thinking that there should be some hard, nice cutting foam - not Styrofoam. My problem with Styrofoam is that it would get everywhere in the shop. Loves static electricity and all that kind of stuff. I would be finding it in my shop for the rest of my life. I do not know if any foam out there would be any different. That is why I am asking the group. I figure there may be someone out there who has worked with foam and has some info to share.

Is there any kind of foam out there that would turn well?
I know they use foam for structural shapes now. What kind of foam is that? Does it work well?

The reason for using foam is that it would be easy to shape and fairly inexpensive.

I might have to cut up a bunch of wood blocks and glue them together and turn that. In the end, I may just do that.....but thought I would ask the foam question first. Always trying to learn something.

I like the foam on the top of a draft beer....I understand that kind.
Thanks.
Hugh
 
Interesting question. I don't have an answer. I also used to do stained glass lamp shades, well before I started turning. I've thought about turning forms for lamps, but never got close to actually doing it. I'll be interested to see if some useful suggestions are posted -- maybe it would encourage me to finally go back and use some of the many sheets of glass I still have in my shop (now well covered with dust).
 
2 part urethane expanding foam from US Composites, you'll want the 16lb density version: http://www.uscomposites.com/foam.html

you can also find foam sheets or pieces locally, but it very expensive.

A well known artist in our club recently spoke about turning foam while talking about one of his pieces - he bought a 4'x8x'8" sheet of 20# density. I think he said the sheet was $1200
 
Azek turns well

I have used Azek, which is PVC foam core trim used on houses. You can get it in planks and sheets. I think the maximum thickness may be 3/4 inch, but it glues together easily and turns much like wood. I have used it along with PVC pipe fittings to make vacuum chucks, and it was easy to turn. It is pretty rigid, but you would not be able to use polyester resin for a mold unless you coated it, because polyester resin will melt the PVC.

David Jones
 
Thanks for the response. I had no idea that it would cost that much. It would be cheaper for me to cut up some of the wood I have collected, into little chunks and then just turn that. Sounds like that is what I will try. Fiberglass lamp molds cost about $150 - $250. Sounds like the foam would be much more. Wood will work. It worked for Louis C. Tiffany. Should last forever too. Just another project. I too have a bunch of sheets of Bullseye and some old Urobos glass that is just collecting dust. Trying to think of projects to use some of it.

Thanks.
Hugh
 
Segmented turning may be the way to go. I've turned the 2"
Blue foam. With a dust collector it's not that bad.
 
have you thought about making your own fiberglass molds? Rubber ball, plastic, fiberglass, resin and you have a mold. Bit messy yes, but so are wood shavings. Also much lighter and easier to store than a wood mold. Also bamboo works well and is "fairly" easy to turn, you would have to glue it together also.
 
OT Question

It was my impression that SG molds had to accommodate push pins or brads to hold the glass pieces in place until the lead cames are added and soldered in place. Wood would be fine, but how does that work with fiberglass?
 
All the lampshades I have made were copper foil, no lead came whatever (up to 20" diameter). I simply put a little 'roll' of masking tape on the back of each piece to hold it on the mould/form. I never had problems with any dropping off. So the material of the form was irrelevant (in my case, usually styroform, which did not take kindly to runoff excess solder; but even those forms have served for many shades).
 
There are composite aircraft structures with rigid foam cores and laminated Fiberglas or carbon fiber skins. The foam is cut with a hot wire. You could contact the Experimental Aircraft Association to get pointed in the right direction to find this sort of stuff, but I feel like that isn't really the best solution to your problem unless you are thinking of mass producing those lamps.

Your question is a bit confusing because I can't tell if you want to make the mold out of foam or the form out of foam.
 
Thanks everyone. Good stuff.
Mark - Tiffany type of lamps are made with copper foil around the edges of the glass. I am like R. Henrickson and use a little piece of painters tape to hold the glass to the mold.

Bill - I want to make a form in the shape of a lamp I want to make. Basically....turn a bowl and turn it upside down. Draw the design on the mold....copy the design off the mold and then cut the glass. Tiffany lamp molds were made out of Rock Hard Maple if I remember right. The idea of using foam for the mold was just a bit laziness on my part. I thought it would be easier to turn and shape. But - the foam thing may be too complicated. Glued up blocks of wood - the way it was done 100 years ago might be the best way to go.

Sometimes I think about things too much...but sometimes I think it is good to wiggle my mind a bit and try to figure things out. You guys help with the foam knowledge as I know nothing about it. Studied Biology not "plastics".

Thanks for all the thoughts people.
Hugh
 
That seems like a confusing way that Tiffany made the lamps if I follow you correctly. I would have thought that an easier way would be to make the form that resembles the lamp out of wood and then make a casting die or mold from something like plaster that can be poured around the wooden form in mating segments. Then after some cleanup, alignment pins, and hole drilling to allow casting material to be poured in and escape passages for air, you would bew ready for making lamps. Or, maybe in my case just buy one. 🙄

For complex shapes, the lost wax process is used, but then the mold is only good for one use since it has to be broken to get the casting out.
 
You could make a mold from wood and then if properly sealed, use expanding foam and turn it. The trick is the sealing and releasing, you need to make sure it is sealed well, thinned lacquer works. Then a mold release to make sure the foam structure comes out. You also need to have a top cap to the mold so that what gets poured in and expands gets good compression to keep enough density to turn.

have used this method several times for making molds
 
This mold I want to make is for me only. I do not want to go into production. Others have done that. I just thought it would be fun to make my own. I have made some lamp molds in the past using sheet metal for making a cone shape and things like that. Simple shapes without compound curves. I think I am just going to use wood.

Bill - sometime - Google "Tiffany stained glass lamps" and maybe click on the images. Should come up with plenty of examples. I am not trying to make molds for blown glass lamps. Could and has been done. But I do not do hot glass.

Thanks for the ideas everyone.
I want everyone who visits this forum....that I enjoy the back and forth that goes on. Lots of good knowledge gets passed around. Cool.
Hugh
 
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