UKPonchoMan Posted December 26, 2008 Share Posted December 26, 2008 I'm starting a couple of vacuforms - Proteus C-131 and Welsh Models Gulfstream IV, both in 1/72nd... Something I've always wondered - I'm used to marking around the pieces, cutting them out and sanding down the edges to the marked lines. However, surely this narrows the fuselages by the width of the plastic? Does this make sense, or and I misunderstanding how the masters are cast? Thanks, and a Happy Christmas to all! Chris Quote Link to post Share on other sites
Big Kev Posted December 26, 2008 Share Posted December 26, 2008 I've always wondered that myself. The how-tos always talk about making sure that you sand away all the plastic to the marked line, but you'd figure the master encompasses the thickness of the plastic, and if you sand it away, you're part is now too small by that amount. I suspect the answer comes down to male vs female moulds, but I'd love to hear from someone in the know. Kev Quote Link to post Share on other sites
Grey Ghost 531 Posted December 26, 2008 Share Posted December 26, 2008 (edited) The guys who make the masters take the thickness of the plastic into consideration. The molds used are female molds, the plastic is sucked down into a cavity shaped like the part. The centerline of the fuselage (for example) is flush with the surface of the mold, so, when you sand away the stock, you're left with a part that is complete to the centerline. For male molds (which don't give you much fine surface detail) the cut line for the part is usually a bit above the surface of the mold, the master is raised a little over the substrate. Otherwise, the molding process won't capture the lower edge very well. Think vac-formed canopies, they're usually male molds. Edited December 26, 2008 by Grey Ghost 531 Quote Link to post Share on other sites
maverick728470 Posted December 26, 2008 Share Posted December 26, 2008 Here is what i do when i do a 32nd vac.U'er ok on the cutting of the parts and popping them off the carrier sheet and sanding them down.One would think the the thickness will cqause problems when gluing the parts together.But i use thin balsawood strips to the inside edges of the fuselage halves,then sand then even and flat to the edge.That way it will give strength annd will make it easier to glue the halves together.Larry Quote Link to post Share on other sites
UKPonchoMan Posted December 27, 2008 Author Share Posted December 27, 2008 Aha, that makes sense now! Thanks all! Chris Quote Link to post Share on other sites
mig23 Posted December 27, 2008 Share Posted December 27, 2008 Ay up Chris, By coincidence Colin is recording his build of the Broplan Gulfstream over on the IPMS(UK) forum. An encouraging guide !.... http://ipmsuk.proboards20.com/index.cgi?bo...amp;thread=4467 Cheers, Haydn. Quote Link to post Share on other sites
UKPonchoMan Posted December 28, 2008 Author Share Posted December 28, 2008 Very good stuff... - I will be following with great interest... Quote Link to post Share on other sites
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