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Old Feb 04, 2013, 06:05 PM
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Template material?


Hi all,

I've just started to cut my own foam cores but I'm getting poor results. Now some of this I'm sure is my own tequnique but probably not all.

I think I could give myself a better chance with some better materials. Currently I'm making my aerofoil templates from 1/16 ply. It's east to work but hard to get a good finish on and the hot wire easily snags causing hills and dips in the foam.

I've heard Formica is a good material, but I can't seem to find a source on the net in the uk? Are there other materials that I should be considering?

Cheers

Tom
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Old Feb 04, 2013, 06:43 PM
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http://www.topclasscarpentry.com/mak...ate%20Samples/

Buddy of mine lives in London buys his as samples and offcuts from Top Class.


T.D.
Old Feb 04, 2013, 07:04 PM
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Whichever material used, work hard to achieve a glass-smooth edge.
Old Feb 05, 2013, 02:21 AM
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Quote:
Originally Posted by rick.benjamin View Post
Whichever material used, work hard to achieve a glass-smooth edge.
I used to sand the guide surfaces of the ply very smooth, sometimes paint it with a lacquer to fill the pores, then apply a thick coat of carbon (with a carpenters pencil) for the wire to slip over. And go easy on the wire-pressure (downwards). Had good results this way.
Old Feb 05, 2013, 05:31 AM
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Hi Sarboy


Quote:
Originally Posted by Sarboy View Post
Hi all,

I've just started to cut my own foam cores but I'm getting poor results. Now some of this I'm sure is my own tequnique but probably not all.

I think I could give myself a better chance with some better materials. Currently I'm making my aerofoil templates from 1/16 ply. It's east to work but hard to get a good finish on and the hot wire easily snags causing hills and dips in the foam.

I've heard Formica is a good material, but I can't seem to find a source on the net in the uk? Are there other materials that I should be considering?

Cheers

Tom
Try thin Aluminium sheet 1/2mm thick works great for me..
John
Old Feb 05, 2013, 06:20 AM
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A good option for"disposable" templates is 2mm cardboard from an arty/crafty shop.Sold as backing board.It cuts really well-with a good sharp exacto and a spray glued paper pattern it's possible to cut in one pass.The knife blade leaves a polished surface.
A good way to get a smooth surface on a ply template is double sided tape and thin strips of aluminium(kitchen)foil.Works a treat.
Do some trials- I like the carbon from a pencil idea,I'll probably give that a go.
Old Feb 06, 2013, 12:27 PM
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I have used 1/16 ply with good results. I sand the edges with 400 grit paper then soak the edges with thin CA. After that I polish again with 400 and 600 paper until it I can run my finger nail along the edge without it hanging.
Old Feb 06, 2013, 07:41 PM
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thick cardboard, soaked in thin CA, then sanded with 400 grit, another pass of thin CA and re sand.
Good thing with cardboard is you can cut it with a stanley knife accurately, so I have found that it is the most time efficient way to get templates cut.
You can re use them as well - probably not indicated for heavy usage but I have had no problems re using the same set 4/5 times which is probably enough for most of us
Old Feb 07, 2013, 11:21 AM
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Try brass once you have the foil shap and design you want. The resign being that brass has a natural lubricity to it, also take some 300 grit sand paper to the aluminum or brass and polish the edge and you should get a real nice cut. Thats just my two cents.
Old Feb 07, 2013, 12:32 PM
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Polish the ply with 400 grit, then CA if you want as shown above. Last (important) step, take a pencil and completely coat the surface that the wire will touch. You'll find that the graphite lubricates the ply very well and wire will NOT snag again.

Construction pencils (the big ones at HD or Lowes) that have rectangular lead are great for this and stupid cheap.
Old Feb 08, 2013, 01:32 AM
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New templates with new front design and using dremal in a piller attachment to sand. This allowed a high degree of control in the sanding process. I then coated them in pencil lead/graphite. This has now produced much better cores. Here are some pics.

Old template design.

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Last edited by Sarboy; Feb 08, 2013 at 01:47 AM.
Old Feb 08, 2013, 01:37 AM
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The new templates. I know this is quite a common shape but until I'd made a couple of cores I hadn't appreciated the advantages.

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Description: New template. Notice how the front of the template allows smooth transition around the leading edge.
Old Feb 08, 2013, 01:42 AM
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Here you might be able to see the carbon/graphite coating.

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Description: Graphite coated top surface.
Old Feb 08, 2013, 01:44 AM
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And the core this all produced. It's a vert stab.

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Description: Vert stab for DLG.
Old Feb 08, 2013, 07:12 AM
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I recoat mine every few sets of cores. I've been cutting cores since the 80s using 1/16 ply and graphite... Always make your final sanding pass by hand chord wise so you take off any micro bumps or ridges you can't necessarily see.

Good stuff! What foam are you cutting?


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