graham kindberg1 Posted June 12, 2012 Share Posted June 12, 2012 Can any one help with some advice on vacuum forming ? I have pulled some cowlings using ABS plastic, and am getting some rather bad stretch marks! I could be using too high a temp to soften the plastic? (210c) I am just starting to suspect the ABS may be quite old, don't know if this would affect the properties of the plastic? Graham Quote Link to comment Share on other sites More sharing options...
Ben B Posted June 12, 2012 Share Posted June 12, 2012 That's awfully hot for ABS. Most of the resources I have seen state you want about 250 degrees F, not 210 C... (250F=121C). Quote Link to comment Share on other sites More sharing options...
Ben B Posted June 12, 2012 Share Posted June 12, 2012 Actually just double checked- remembered it wrong **LINK** 140-190C stated on that reference. 210C is a bit OTT though. I'd try going for the lower end of that range but bear in mind too cold can cause similar problems. I'd use an IR pyrometer to confirm the temp before the pull. If it's too hot let it cool a bit first. Quote Link to comment Share on other sites More sharing options...
Danny Fenton Posted June 12, 2012 Share Posted June 12, 2012 Hi Graham, are you vacuum forming or just pulling the ABS down over a mold? I found when doing some spinners I was getting poor results so upped the material thickness dramatically. Bear in mind I was using a vacuum to pull the shape. I have no idea about the temperature but it was very hot. I left my plastic under the grill, with the door shut until it sagged a good 2" inches in the centre of the A4 sheet frame, to which my ABS was stapled. It took several minutes. Cheers Danny Edited By Danny Fenton on 12/06/2012 15:53:28 Quote Link to comment Share on other sites More sharing options...
graham kindberg1 Posted June 12, 2012 Author Share Posted June 12, 2012 Thank you for your suggestions Ben and Danny, I started at 180 degrees and felt it was taking too long to sag, so upped the temp. Was getting the same results at both temps though. I am using 2mm material as i didnt think that 3mm would pull down tight enough at the bottom. I even did a test run with the ME109 plug that i usually pull 3mm on, it also ended up with the "orange peel finish, hence my suspicions about the quality of the ABS. Will post some pickies later today. It is vacuum forming Danny, usually do canopies with acetate and no problems. Graham Quote Link to comment Share on other sites More sharing options...
Danny Fenton Posted June 13, 2012 Share Posted June 13, 2012 I suppose the quickest to eliminate will be the ABS by trying some fresh? You are using much thicker material than I have used. Good luck Danny Quote Link to comment Share on other sites More sharing options...
graham kindberg1 Posted June 15, 2012 Author Share Posted June 15, 2012 The ABS was " fresh" from the suppliers, however it does show a faint discolouration! Trimmed cowel in all its orange peel finnish Filled and under coat Painted And fitted! overall i am happy with the forming of the cowling, just could do with out the rubbish finish Graham Quote Link to comment Share on other sites More sharing options...
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