THE SMA FORUM ARCHIVE
Posted by Simon (Guest), on 2001-03-17 12:28:01
Hey Nick - magnents
NOTE: the following messages have been transferred from the original SMA.com Message Board
User ID: 9099093 Feb 2nd 6:46 PM
Hey Nick where would you buy really powerful magnets for feet (and small as well) in Australia?
User ID: 1752694 Feb 4th 4:47 PM
Sory Simon, I don't use them. A friend of mine (now doing computer animation in Bristol, UK) bought some very powerful rare earth magnets here for his film in 1993, I had a play with them but they didn't suit the rough ground of the sets I was using. Magnets need a flat surface to grip to. Despite the hassles of drilling holes, I find tie downs are more secure. The most likely suppliers listed in the Melbourne Yellow Pages under Magnets look like Oriel Magnetics in NSW ph 1800 771 877 email@example.com, or D&D Magnets (NSW) ph 1800 500 202, or A Aussie Magnets (VIC) www.aussiemagnets.com.au. Check your own city, might be something there. I vaguely remember these magnets were expensive, maybe $16 each?
User ID: 9161143 Feb 5th 9:40 PM
Magnetic tie-downs has it's idiocyncrasies. Puppet makers,Mckinnon & Suanders advised the "PJ's" production (Vinton studios) how to go about it. Basically...it's about 16 gauge thickness perforated (with 1/8" holes) steel sheet....then you have to put cross brace supports under sheet metal so that it will not sag. The floor design or pattern is drawn,photocopied or painted on the thinnest paper. Anything thicker than paper will greatly reduce the magnetism force (from under the animation stage/floor) which has to penetrate the sheet metal, paper, then finally, hold down/grip the puppet's feet. So with magnet tiedowns you can possibly be limited to the type of sets (no thick ground/terrain type sets).
I found it difficult to handle armatures using magnetic tiedowns...the armature has to have a much "looser" joint tension. In a puppet walk cycle...as you push/animate the moving puppet leg, your other hand must grip the stationary leg so that it won't slide around. Magnets does somewhat hold down the puppet's feet, but feet has tendency to slide around within the magnetic field. It is a totally different & odd sensation to try and animate with this tie-down system and I suppose you have to adapt & get accustomed to it. Stop motion animator Barry Purves and other Brit animators apparently have the patience to master the subtlies of using magnet tie-downs. Also, I see a possible problem if the puppet is top heavy and has small feet. On the PJ's, the magnet tie-downs, worked somewhat better for puppets with really big feet.
Yes, rare earth magnets can get pretty expensive (it can be much more than $16)...I think one magnet type is called Neodymium, but there are other rare earth magnets.
The reason for the holes in the sheet metal floor, is, so that the stop mo animator can use the more secure, screw tie-downs (4-40 threaded rod slides through 1/8" hole).
User ID: 9099093 Feb 6th 6:09 AM
So how do you have your sets setup Nick? So you can drill the holes...?
User ID: 1752694 Feb 6th 5:01 PM
My sets usually have a floor made from 12mm (1/2") particle board. It's stiff enough not to need a lot of support struts in the middle, it sits on a folding rostrum made from 3x1 pine. If it's got to look like rough ground I build up with plaster, if its a smooth interior floor I paint it. Sometimes I use coarse velvet or chenille fabric for a carpet look. I drill 1/4" holes where I expect the puppets to walk, before animating the shot. (Drilling during a shot can move things about.) If carpet goes on top, I cut small slits where the drilled holes are. The slits are usually invisible. My puppets have aluminum blocks in the feet, with slots in them for the T-shaped tiedowns. On bare floors I usually fill the tiedown holes with cloured plasticine. It's easy then to poke the plasticine out when pushing the tiedown up from below. One early set had a floor painted like a bold patterned carpet, and I predrilled holes in all the dark patches, so it just looked like part of the pattern. Another set used a sheet of perforated steel, with a grid of holes - no need to hide them, it was part of the look, but it needed frames underneath every 18" or so to support it.