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felixe
9th July 2007, 09:18 AM
Hi Guys,

I have a curly question and woodturning is the best place to start.

I need to make a mock football, a sherrin (AFL). Due to weight etc etc a real sherrin is out of the question.

My thoughts are to "turn" a polystyrene cylinder until I get the shape and finish from there (it will have an imitation leather cover etc).
I don't have a lathe but I do have a big old bench mounted drill press to use as the lathe. I am getting an actual football for the shape and I have a profile gauge from carbatec to copy the shape.
So, is it possible and what chisel/cutting tool is best to pare down the shape. Prior to turning I will be using the bandsaw to cut off excess waste.

I am not on drugs.:no: This does need to be done so input is really needed.:2tsup:

I have cut and shaped polystyrene before and realise it will make a big mess so I also have the dusty at the ready.:U

Your thoughts please.................

rsser
9th July 2007, 09:23 AM
Maybe if you can soak it in something to firm it up.

Or maybe mount it and use a rasp or surform rather than a chisel.

If you're not on drugs maybe you should be :D

Sebastiaan56
9th July 2007, 09:33 AM
I remeber shaping polystyrene with hot wire, bent to shape and then heated on the stove, forget what the drug was though..

Sebastiaan

Bleedin Thumb
9th July 2007, 09:42 AM
I think you would be better off with a hunk of polyurethane foam that you can shape with rasps and sand as in surf board blanks etc, I would have thought that polystyrene would tear out too much.

I can recommend several fine drugs.

cedar n silky
9th July 2007, 10:17 AM
What about the foam they use for surfboards? It is far easier to shape, although I am not sure how thick they make them. You could always glue them together if they are only say 75 mm thick. I am sure surfboard manufacturers throw away a lot of waste.

rsser
9th July 2007, 10:17 AM
... reminds me: don't breathe the fumes of burning polystyrene. Big hit but very toxic.

felixe
9th July 2007, 10:32 AM
Surform is not a bad idea:doh: It does clog up a bit.

Don't know about tearout, I have cut sheets on a tablesaw and bandsaw with no tearout, I have also used a reciprocating saw ( a dodgy GMC Tyranosaw which shook my arms off:o ) and a tenon saw also with no tearout. The resulting surface is slightly textured but it is the "core" and not the finished surface so this is acceptable.

Do you think a spinning piece of polystyrene will take out chunks (tearout) with a wood turning chisel?

I was actually considering a blade from my No 6 Stanley, using it to shave as it spun around?

felixe
9th July 2007, 10:33 AM
Thanks for the warning rsser, I am aware of the fumes and the workspace is ventilated with extraction (under the house with both the DC and shop vac running).

soundman
9th July 2007, 11:04 AM
I think shaping on the lathe would be a problem.

Unless you mounted it on a mandrel, and that would have to be quite a large diameter to get a secure drive.

If you are looking at rigid foams there would be better choices than polystyrene.

there are shaping tools specificaly designed for working in polystyrene.
one other problem is that poly styrene ie quite coarse and it is very much prone to tearing out the little ball bits... the finish will be quite coarse unless you are cutting at speed with a very sharp tool.

one of the finer grained rigid foam would be a better choice, some of those are often worked with a vegitable peeler.

have you thaught of taking a mould of a real football & then casting in expanding foam.

you could make the mould, coat the unside with the correct coloured latex (after mould release), & then fill it up with canned expanding foam... It would be very convincing.

Plaster bandages could be used to make the mould... you will need to use some sort of release agent and introduce a split seam.

or perhaps the two part plaster cast method.
pour the bottom half cast in a box, press in the football till half immersed.hold it down while it sets with straps
true up the mating surface & add a release layer then pour the top half.

Oh hell there are books written on this stuff.

one warning though... never try to cast body parts in plaster...it gets quite hot as it cures, particularly in volume and very nasty burns can occur.
For casting body parts you need to use alginate.

cheers

Cliff Rogers
9th July 2007, 11:09 AM
...one warning though... never try to cast body parts in plaster...it gets quite hot as it cures, particularly in volume and very nasty burns can occur.
For casting body parts you need to use alginate.....

OK, I'll bite..... How do you know? :p

Iain
9th July 2007, 11:45 AM
How about a latex mold, like them little garden gnomes etc, just prep a footy, paint on the latex, cure, peel off then fill with foam/styrene, cure, peel off, voila!!!
And you realise of course why the footy is that shape, to do with soccer and a country boy playing the game.........................:rolleyes:

soundman
9th July 2007, 11:47 AM
:D :D
there are three main industries that cast body parts from life.
medical prostetics
the sex industry
magic prop makers.

A friend of mine builds very nice magic props.
A convincing arm, leg, hand or foot can be very usefull to a magician from time to time.
believe me if its properly done it is very hard to tell the difference.

I knew someone would bite:D :D

cheers

felixe
9th July 2007, 11:53 AM
Hi Soundman,

Thanks for the feedback. I have my theory books on mould making and some experience however mould making is out, I do have the hydrocal (plaster) and silastic to do the job but the time frame for making and curing multi part moulds and the cost are both greater than shaping a $20 block by hand which should only take a few hours.

I envisaged I would pre-shape the block and then turn it on the drill (skewered on a long piece of hardwood dowel) to obtain an even shape.

I have taken advice onboard about my choice of foam and have sourced some blocks of polyurethane foam for the footy!:2tsup:

Funny you mention casting body parts and materials. I also have to do the hands (taking the mark) and I am off tomorrow to buy my algenate. Another point worth mentioning is that alginate (or any flexible material) also allows the production of a quicker 1 part mold which I can then extract my hand(s) from and cut with a mold knife (producing a multi part mold)
Not to mention the trouble you would be in if you could not get your hand out of plaster.:doh: :o

Keep the suggestions coming, this is a great help!:2tsup:

Gra
9th July 2007, 11:55 AM
:D :D
there are three main industries that cast body parts from life.
medical prostetics
the sex industry
magic prop makers.

A friend of mine builds very nice magic props.
A convincing arm, leg, hand or foot can be very usefull to a magician from time to time.
believe me if its properly done it is very hard to tell the difference.

I knew someone would bite:D :D

cheers

as long as it was only an arm or a leg:whistling2:

felixe
9th July 2007, 11:56 AM
Latex is out as the curing time is too long (usually done in layers) silastic silicons are better for use with the range of setting times, shore hardness and the detail they capture.

but the cost of silicon (including labour) moulding is far greater in this case then just shaping a "pill"

soundman
9th July 2007, 12:02 PM
Yeh.. a couple of problems with the latex mould.
Because it is an enclosed shape, it will be a problem getting the real footy out & re closing the mould.
secondly, unsupported latex moulds arent real stable, generaly they will be supported by a plaster carrier or something.

Dont confuse this with the thick silicon moulds... even then they are best supported by a carrier and are usualy open topped.

What we are looking at here is like moulding an easter egg.

have you thatugt about trying to find a full sized plastic footy or a blow up one.

If this is to be done realy well, it starts getting into exotic stuff that aint cheap.... working in plaster is prabably realistic.

cheers

cheers

reeves
9th July 2007, 12:05 PM
On the woodturning centre site theres some art pics of styrofoan turnings,,,looks weird but i guess its valid to some extent..

for yr football, some of the suggestions made are probably good but have you thought of polyester resign, like make a mould in the rough shape, the resin comes in powder form i believe and you mic it up and paw it in. Then whack on yr drill or lathe and turn it to shape then make the markings. U can add dyes and such for color...

Also lighter wood like red cedar would turn or carve a cool foootball.....just an idea...

felixe
9th July 2007, 12:17 PM
Hi Reeves,

can you post a link on the site for the styrofoam turnings?

The footy is mounted in hands so the lighter the better, the hands are going to be made of chocolate cast into an alginate mold.

I will pass on the resin, I still like the idea of a polyurethane foam block which I can bandsaw to rough shape and then maybe turn to get my football/easter egg.

I was thinking when turning that i work with the rotation, shaving off foam rather than against the rotation.

Manuka Jock
9th July 2007, 12:19 PM
You could use an electric planner , for shaping . It works well on polyurethane .
Check out the thread about it on here .
http://www.woodworkforums.ubeaut.com.au/showthread.php?t=52154

With a dowel , or threaded rod running thru the block of poly , and having it running between the drill chuck , and a housing clamped to the base plate , things should go ok .

Jock

if ya lay the drill press over on it's side , like a real lathe ........:p

soundman
9th July 2007, 12:30 PM
Ahh thats a thaught.
you could bore the block and glue in a dowel permanently.

using a lighter timber such as balsa or philo pine.

you could then chuck the faom up between centres.

get the shape right & do most of your finishing.

then part off the timber at both ends and patch up.

Hmm and you wouldnt need a big lathe to do it either.

Have you thaught about turning chocolate :U I raised the issue a while ago.


back to the moulding body parts...... one of the local ..."experts" arround Brisbane for moulding body parts IS a bit weird.
He has been know to mould an extra one for his private collection:o
It is also said that he does quit a bit of "contract work" :; for one of the other industries.
:o :no: Its getting weird just writing about it.

cheers

felixe
9th July 2007, 01:27 PM
Yes, so I plan to mount the foam on a dowel rod, and given the inspiration of the "planer use on a woodlathe" thread I am thinking:

Low speed drill press and a coarse belt sander hooked up to my shop vac:2tsup:

robyn2839
9th July 2007, 01:32 PM
why dont you just buy a cheap ball ,if your going to cover it with leather no one will know the difference. bob

TTIT
9th July 2007, 02:33 PM
Felixe - take a leaf from Hardenfasts book - use the drill-press as you were planning but use an electric planer to do the shapeing. The high speed of the plane will (should!) leave a clean surface and you can hook up the vac to it for the mess. I've seen surfboard makers shaping with the electric planer - gotta work! :shrug:

Gil Jones
9th July 2007, 03:23 PM
Felixe, check your email...

Also, is this what you are after? >> http://www.n-fl-woodturners.org/images/2006-12/2006-12-23s.jpg

reeves
9th July 2007, 03:26 PM
Felix, a little bit of info here

http://www.everything2.com/index.pl?node_id=1544652

the turned foam Vessels I saw were somewhere on this site, in an exhibition page the guy just had some styrofoam vessells as part of a gallery exhibit...cant recall exactly which one..

http://www.woodturningcenter.org/

halfway down this page a guy is turning foam..

http://www.lynneyamaguchi.com/wordpress/
http://www.lynneyamaguchi.com/wordpress/2007/07/06/friday-july-6/

felixe
9th July 2007, 11:38 PM
Many many thanks to all those who contributed suggestions.
Greenies to you all!:brava :hpydans2: :D :D :D

littlebuddha
10th July 2007, 12:01 AM
How about a cheap plastic football as a mould and use a can of expanding foam, the foam doubles its size, take out the valve and put the tube of the foam can through anything thats not needed expands through the vavle hole. but dont think you would turn foam on a lathe unless you get that blue foam the nonextrude whatever its called the one not made of small balls, they use it for making model plane wings and such.

Gil Jones
10th July 2007, 04:26 AM
Felixe,
I forgot that I could post a .pdf here, so most of the "How To" data, and a segmenting pic is in this file. Actually, it is just a newsletter from our turning club. His wooden football is very nice up close. Have fun....:)

China
10th July 2007, 05:28 PM
When you buy your foam ask for model makers foam it is specifcaly desighned to be shaped and will save you a lot of head akes