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Author Topic: Team Go Dog, Go! Modified Partial Streamliners  (Read 1007378 times)

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Offline 4-barrel Mike

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #705 on: March 06, 2012, 05:30:55 PM »
Mike Kelly - PROUD owner of the V4F that powered the #1931 VGC to a 82.803 mph record in 2008!

Offline wobblywalrus

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #706 on: March 06, 2012, 11:55:54 PM »
The bubble method will be what I do if the molding procedure does not work or is too expensive.  Right now the mold is a good thing.  Making it is forcing me to figure out exactly what I want and it gives me something use as a reference for the sheet metal work.   

The plastic sheet is rectangular.  The long dimension is plenty and I am not worried about it.  The short dimension is 24 inches wide and it is the critical one.  The the mold cannot be wider than 20 inches so everything will fit into the oven.  The flanges are 1.5 inches each.  They will be cut off after the windshield is vacuum molded.  See the sketch.

People I talk to say there are lots of different ways to do this and they need to look at the mold before they can give intelligent answers.  That is logical. 

The shield might be vacuum molded or it might not.  There are two local plastic companies in this little town and one fellow says he can lay felt over the mold and form the plastic over that using heat and his hands.  I might let him do it first and stand by to watch if he lets me.


Offline wobblywalrus

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #707 on: March 08, 2012, 12:45:37 AM »
Any suggestions on the plastic?  My idea is to say "I need shatterproof plastic like the racers use."  That is not a very sophisticated request.

Offline wobblywalrus

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #708 on: March 09, 2012, 12:21:51 AM »
Some internet research tells me that polycarbonate is best and hard coated poly resists scratches better.  Lexan is a brand of polycarbonate.  Next best would be top grade acrylic. Lucite and Plexiglas are acrylics.  Regular basic acrylic would be the bottom of the line choice.  I will try to get the shield made from hard coated polycarbonate.

My son sent me this picture from Afganistan where he is on patrol.  It looks like Nevada.  He will be back later this month. 

Offline Peter Jack

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #709 on: March 09, 2012, 04:56:35 AM »
Bo, research polycarbonate, i.e. "Lexan" or "Margard", carefully before you start to heat and form it. It must be baked at controlled times and temperatures to drive out moisture or it bubbles internally and that's it for visibility. I'm not sure how the anti-scratch is applied but I would think it's a post forming process that would be ruined in the forming process.

Pete

Offline Freud

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #710 on: March 09, 2012, 11:06:09 PM »
Let us know when he gets home.

Sometimes the last day is a killer.

FREUD
Since '63

Offline wobblywalrus

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #711 on: March 10, 2012, 12:17:57 AM »
Hi Freud.  Thanks for the advice.  It is passed on to him. 

Offline wobblywalrus

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #712 on: March 11, 2012, 12:10:57 AM »
The ignition module came in the mail.  It was reprogrammed in England to Triumph Performance specs.  It has the Option 3 settings.  This is the rev limiter raised to 8,400 rpm and a remapped spark advance curve.  The settings are made for an 865cc with the #813 cams like I have.

This morning I got up early and glued the last pieces on the windshield mold, removed the mold from the fairing, and sanded it down with a belt sander.  This roughed out the shape.  Next, I sanded it with a palm sander.  Finally, I started the finishing sanding by hand with a sanding block.  It goes up to Kent Plastics on Tuesday afternoon.  It looks like a wooden turtle.

Offline wobblywalrus

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #713 on: March 12, 2012, 07:47:28 PM »
Real early this morning I brought the mold to a local plastics company.  Initially we talked about polycarbonate windshields.  This is my first choice.  His procedure is to put felt over the mold, heat the plastic, and to stretch it over the mold.   He said polycarbonate is hard to work with.  It has a memory and it tends to spring back rather than to conform to the mold.  He said initial preparation is essential.  The plastic must be heated to get rid of gasses in it.  He said these problems were worst with thicker plastic.  Polycarbonate is a material best suited for shops who use it on a frequent basis and have the curing facilities and experience to handle it, he said.  He said it would take two or the three tries for him to get it to work.

We discussed acrylic.  The regular acrylic is used for windshields, he said.  It shatters.  He said the tougher acrylic grades are sort of between polycarbonate and regular acrylic in workability. 

Offline wobblywalrus

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #714 on: March 12, 2012, 08:13:35 PM »
This is part two.  Rosie came home with dinner and I had postus interruptus.

The conversation ended with a homework assignment for me.  It is to figure out which acrylics are suitable for racing use.  Some quick research and Tom's post says aircraft grade cell-cast acrylic might be an alternative to polycarbonate.  Hopefully the sanctioning bodies will agree.  The Polycast UV-SC is claimed to be suitable for thermal shaping.  www.polycastacrylic.com.  Tomorrow I will bring the mold to Kent Plastics and talk to them. 

Offline wobblywalrus

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #715 on: March 13, 2012, 11:00:53 PM »
Today I had some business in Portland in the morning.  In the afternoon I visited the two plastic shops I am working with to do this.  I had the mold with me.  One shop does vacuum molding.  They would start with a 3/16 inch sheet and pull it down over the mold.  It would be about 1/8 inch thick in places where it was stretched the farthest.  The minimum thickness I want is 1/8 inch so this would be OK.  The plastic would be very soft when the molding is done.  It would pick up all of the grain texture from the wood.  I would need to sand all of this out of the inside face of the windshield.  It would be a big job.  Normally they do vacuum forming over polished metal molds and this is not a problem.  My conclusion:  vacuum forming is not practical for a wood mold.

Next I visited the shop that would slowly heat the plastic, drape the plastic over the felt covered form, and pull it into shape by hand.  They would start with 1/8inch thick plastic and they did not expect it to get much thinner.  Their oven was just big enough to hold the plastic.  They did not think they could heat the plastic evenly and some spots would be cool and not workable.  They recommended a shop in Hillsboro with a bigger oven.  They also mentioned that mold defects would show up on the windshield after the molding and fewer would be there than with the vacuum process.

Both shops would use generic polycarbonate or acrylic.  Hard coated windshield polycarbonate or aircraft grade cell-cast acrylic is what I want.  I would need to supply these materials myself.  A sheet of plastic is typically 4 x 8 feet and this costs a lot of $.

My plan is to smooth out the mold a bit more and bring it up to the big plastic shop in Hillsboro on the afternoon of the 22nd.  The dyno work will be done that morning in the nearby town of Beaverton.

Offline Peter Jack

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #716 on: March 13, 2012, 11:21:16 PM »
Check Home Depot. Up here they have smaller sheets. I think they buy 4 x 8 sheets and cut them up.

Pete

Offline wobblywalrus

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #717 on: March 14, 2012, 08:34:24 PM »
The local plastic shop has been helping me quite a bit with advice.  I will let them try it.  I sort of owe it to them.

The local shop looked at pricing for cell-cast acrylic sheets.  It is scarce and expensive.  Their supplier recommended PETG.  It is easy to thermoform and it does not have the moisture absorbing problems of polycarbonate.  Some internet research shows that it is very tough.  Type "Quinn PETG" into a browser if you are curious.  Quinn uses it for motorcycle windshields and they produce it with UV resistant additives.

The wood mold is getting the final sanding.  I asked for a price quote from a pattern maker supply for some "Duratec Vinyl-Ester Surfacing Primer."  It is especially made for sealing wood molds that will have high temperature use.

Right now I am not sure what I will do.  I am learning a lot and seem to be headed in the right direction.  Does anyone have experience with PETG windshields?   

Offline Koncretekid

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #718 on: March 14, 2012, 09:37:13 PM »
Bo,
Cell cast acrylic, or PMMA (polymethyl methacrylate), is a shatter resistant plastic.  According to Wikipedia, it has been used for such things as the windows of submersible submarines, police riot shields, transparent shields at hockey rinks, lens for automobile headlights, the transparent dome of the B-17 flying fortress, and the roof of the Astrodome.  It is used for aircraft windows.  In fact, Lexan is not accepted for aircraft windows because in case of a necessary rescue, it cannot be broken.  Although I don't think this is a big issue for open or partially streamlined motorcycles, I'm not sure I would even want lexan for the windshield of a streamliner.  If they couldn't get the door open, they wouldn't be able to rescue the driver!  There should be no question of its acceptance as a shatter resistant plastic.  I might add that it would difficult to police the issue in any case, as I'm not sure there is any way to tell the difference with a non-destructive test.
Tom
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Life's uncertain - eat dessert first!

Offline wobblywalrus

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #719 on: March 15, 2012, 12:31:49 AM »
The PETG is used for bus shelter windows.  The yobbos cannot break them.  It is also used for windows in insane asylums.  That last use sorta qualifies it for being on my bike.