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Vacuform Problem (Read 372 times)
Reply #11 - Jul 7th, 2018 at 9:41am

Sky9pilot   Offline
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Kelso, WA 98626 USA

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I finally found a picture of the press board with the hole in it.  It's by Chris Starleaf, who I consider a master modeler, I learned a lot of my techniques from following his builds on SFA before it went down.  Kudos to Pete and the fellas there who have resurrected the site and are putting together alot of the archives.  Click Here Reply #286 for a picture.  If you want an inspiring build check out this whole build of a Multi-Rapier B-47 build.
Tom
 

If God is your Co-pilot...switch seats...
Your attitude will determine your altitude!- John Maxwell
And ye shall know the truth, and the truth shall set you free. Jn 8:32
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Reply #10 - Jul 7th, 2018 at 9:27am

Sky9pilot   Offline
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Kelso, WA 98626 USA

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Sounds like you have a good handle on this.  Another way is to cut a cardboard press (for lack of a better term) with a hole in it 1/16" to 3/32" larger than the base of the mold.  Fasten the plastic to the bottom of this press then heat the plastic till it sags.  Immediately press this over the mold till the press clears the bottom of the mold.  This works well in keeping the plastic smooth over the mold and tight against the bottom of the mold avoiding the stress folding of the plastic.
Tom
 

If God is your Co-pilot...switch seats...
Your attitude will determine your altitude!- John Maxwell
And ye shall know the truth, and the truth shall set you free. Jn 8:32
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Reply #9 - Jul 6th, 2018 at 7:59pm

alfakilo   Offline
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Retired USAF and TWA.
St Louis, MO

Posts: 521
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I used some old gardening gloves. Lacking the suction of the vacuform, the plastic needs to be pressed or smoothed down around the mold. It helps to have the mold elevated a good 3-4 inches to allow the plastic to get closer to the mold.
 
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Reply #8 - Jul 6th, 2018 at 7:18pm

Sky9pilot   Offline
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Stick & Tissue
Kelso, WA 98626 USA

Posts: 10049
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For plunge molding, that oven mitt will come in handy for pulling the warm plastic close to the bottom of the plug/mold after it's been passed over the mold/plug.  Glad to see you've had some success! Smiley
Tom
 

If God is your Co-pilot...switch seats...
Your attitude will determine your altitude!- John Maxwell
And ye shall know the truth, and the truth shall set you free. Jn 8:32
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Reply #7 - Jul 6th, 2018 at 4:02pm

alfakilo   Offline
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Retired USAF and TWA.
St Louis, MO

Posts: 521
****
 
I tried the plunge method today when making the P-56 canopy. Came out very well. Much better than the spinner I tried to make with my first attempt

I used the vacuform base and mount for this and found that the plug wasn't elevated enough. I used a piece of hardwood scrap to make an extension of about 2 inches and this did the trick.

I found a hot plate in the Dollar store for about $12 and set it up next to my work bench. I also built a smaller plastic holder out of scrap plywood. This lets me use the leftover sheet from earlier vacuform projects. This plunge method is less hassle than vacuforming...can't say yet that it is better, just quicker.

I redid the spinner using the plastic from an alcohol bottle and used corn starch on the spinner plug. Spinner came out OK bit it does not want to release at all.
 
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Reply #6 - Jul 5th, 2018 at 9:19pm

Sky9pilot   Offline
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Kelso, WA 98626 USA

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I'm sorry...I was miss leading on the drink bottles.  I use this process with my old Monokote Heat gun.  I cut off the big end of the bottle, stick the form inside the bottle and wedge it in place...especially if the form of the plug will fit the contours of towards the neck of the bottle.  I then shrink the plastic around the mold/plug.  This takes practice because the mold want to move and it has to be wedged tightly into the bottle. Heat the plastic all around the mold.  I sometimes clamp the bottle below the plug/mold to hold it in place with locking clamps and visegrips.  If you keep heating the bottle it will heat up and shrink around the mold.  I then use a razor blade or Xacto knife to cut the mold free.  I've gotten some good canopies this way. 

As for vacuum forming go to the supermarket deli section and get the plastic that they pack muffins, donuts and cookies in.  You'll fine lots of yummy plastic to be had.  Sheet cakes also with the clear plastic tops.  These work pretty well with vacuum forming.
My bad with the drink bottles!!! Embarrassed Cry
Tom
 

If God is your Co-pilot...switch seats...
Your attitude will determine your altitude!- John Maxwell
And ye shall know the truth, and the truth shall set you free. Jn 8:32
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Reply #5 - Jul 5th, 2018 at 7:24pm

alfakilo   Offline
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Retired USAF and TWA.
St Louis, MO

Posts: 521
****
 
I've been trying to use the plastic from drink bottles but am not having any luck. The plastic does just the opposite from softening, instead it tightens up and might even pull itself right out of my frame. Completely unusable.

Anyone having better luck?
 
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Reply #4 - Jun 19th, 2018 at 3:24pm

Sky9pilot   Offline
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Stick & Tissue
Kelso, WA 98626 USA

Posts: 10049
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Corn starch is GOOD!!! Smiley
 

If God is your Co-pilot...switch seats...
Your attitude will determine your altitude!- John Maxwell
And ye shall know the truth, and the truth shall set you free. Jn 8:32
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Reply #3 - Jun 19th, 2018 at 8:26am

New Builder   Offline
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Amherstburg, Ontario, Canada

Posts: 739
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Quote:
I lightly dust with talcum powder and then blow off the plug

Alf, suggest using corn starch rather than talc and Tom's recommendations are, as always, spot on. Smiley Talc has been getting some bad press lately and I find other uses for it in my kitchen as well.
Mike
 

Have no fear of perfection - you'll never reach it. (Salvador Dali 1904 - 1989)
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Reply #2 - Jun 18th, 2018 at 6:02pm

alfakilo   Offline
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Retired USAF and TWA.
St Louis, MO

Posts: 521
****
 
Thanks, Tom. I suspected that I should have prepared the balsa spinner with some sort of finish. My guess is that the plastic very closely conformed to the plug and that resulted in not getting a clean release.

I'll try your suggestions next time around!
 
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Reply #1 - Jun 18th, 2018 at 3:52pm

Sky9pilot   Offline
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Stick & Tissue
Kelso, WA 98626 USA

Posts: 10049
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A couple of questions for you.
1. Did the plastic curve under the mold/plug trapping the plug?

2. Or did the plastic stick to the plug?

If the answer to 1. was yes, I usually use a single edge razor blade to cut the plastic flush with the bottom of the plug.  I then massage the plastic to loosen the plug from the plastic till it will release and allow the plug to slide out.

If the answer to 2. was yes...I often use thin cyano glue to seal the plug.  I put a few drops on some napkin/paper towel, and rub this on the plug surface.  Keep the paper moving so the plug is burnished with the cyano.  It sometimes takes a couple applications.  I then use 400 or 600 wet/dry sandpaper dry and sand the plug smooth.  Then before vacuum forming any spinners or canopies etc.  I lightly dust with talcum powder and then blow off the plug.  This leaves enough powder to serve as a release for the plug.  Helps to let the plastic cool completely before trying to remove the plug. A little isopropyl alcohol will clean the plastic after this, leaving a nice clear and clean plastic.  For spinners I buy the plastic picnic plates from the Dollar store in white, black, yellow and red, haven't found any clear yet...to make spinners and scoops etc. Hope this was helpful.
Tom
 

If God is your Co-pilot...switch seats...
Your attitude will determine your altitude!- John Maxwell
And ye shall know the truth, and the truth shall set you free. Jn 8:32
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Jun 18th, 2018 at 12:58pm

alfakilo   Offline
Senior Member
Retired USAF and TWA.
St Louis, MO

Posts: 521
****
 
I'm new to vacuforming, and the spinner that I just made is only my second project.

I carved the form out of balsa, sanded it smooth but did not apply any type of finish.

The vacuform worked fine but I could not release the balsa form and had to cut it out. Spinner is OK but I would have liked to have kept the form.

I used the plastic from a milk jug.

My previous project was a canopy made from plastic sheet from the LHS. It released easily.

Why did I have this problem with the spinner?
 
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