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Creating Clear LM Front Turn Signal Directional Lenses
Posted by: azdave ()
Date: May 27, 2016 02:07PM

If you followed my earlier thread where I was searching for a perfect left-hand late-model front turn signal lens then you might be interested in seeing more about this project.

[corvaircenter.com]


I’m working to produce clear turn signal lenses such as were originally available from Chevrolet for Corvairs sold in several European countries. Those countries, such as Sweden, did not allow amber-colored turn signals and finding original clear turn signals is pretty much impossible these days.

This is far from a full step-by-step tutorial but it will give you an idea of the process involved. I have taken some pictures to share along the way but once I start mixing the molding compound or the clear epoxy the camera gets put away and I concentrate on getting the task completed before the material cures before I’m ready. I am currently making a mold of the left hand lens and assuming it is bubble-free, I may soon be able to produce both a left and right lens.

I am also testing two new clear epoxies that have a much higher glass transition temperature. The materials I am using now produce a lens that begins to become rubber-like at around 120°F. Since the lens is retained by only two screws on the sides I’m worried that the force of the compressed gasket pushing against the lens may slowly push the lens forward in the middle area on a very hot summer day. I am possibly being too cautious in this regard but since the worst summer heat will hit Phoenix in about 30 days I will be prepared to do testing on my Corsa.

A few people asked in the other thread when these might be available. I can only estimate it will be middle to end of summer at best. I will be in China for part of June and I also do not have full use of my right hand yet after some surgery. Once my right hand is at 100% function they will operate on my left hand and elbow too so it’s going to be a frustrating summer.

In a nutshell, here is what I’m doing. Find a perfect part to use as a master. Polish it and make it as perfect as possible. Make a two-part RTV silicone mold by mounting the master to a splitter board. Use clay or other means to keep the molding compound from flowing where it is unwanted. Build a box around the master. Seal the box seams. Mix and degas the molding compound. Pour slowly over the master being careful not to trap any air or cause bubbles to be formed. Place that assembly in a pressure-pot at 60 psi and let it cure overnight. After curing, remove the mold half from the box and the splitter board. Flip the mold and prepared to pour the second half. Build a box around the master again. Use Vaseline or mold release on the cured silicone to prevent the second half from sticking to the first. Mix and pour the second half and put it back in the pressure pot. After 24 hours remove the box from the mold and then very gently remove the master. With the master removed place the mold halves together and post cure for 12 hours at 140° F. After the molds are fully cured decide where you will place the sprues used to fill the mold with epoxy. I use a sharpened brass tube forced through the silicone. To fill the mold properly and be sure the air is burped you want to fill at the lowest point of the mold and have the air lead at the highest point of the mold. This is where it can get tricky deciding where you originally place your parting line based upon the type of master you’re working with.

To make a final part, you may need to coat the mold with release agent depending on the mold material used or the clear epoxy you will use. Most suppliers recommend preheating the mold before pouring the epoxy to aid in helping it flow properly and to make sure thin areas of the casting get enough heat to reach curing temperature. Once the mold is filled it is placed in a pressure pot at 60 psi until it is fully cured. Depending on the epoxy you use some suppliers recommend post curing in an oven while the new part is still in the mold. Other suppliers say it is okay to gently remove the part and then post cure. I think it is best to cure while still in the mold however, this means your mold is not available to pour another part. After the curing the part will need a little cleaning of the casting flash. This is done simply with an X-Acto knife.

That’s all I have for now. Here are some photos with descriptions. As I have more success I will post additional pictures. When I have failures I will quietly hide them in the trash. 

There are dozens of videos on YouTube that I'm sure explain things better than I have done here.


Vacuum de-gassing the silicone compound. A very thick-walled steel pot and a 1" thick Plexiglas lid is used so you can see the process. I already had a nice Gast vacuum pump that I use for automotive A/C work. You de-gas carefully or the container overflows and creates a real mess.




Thick molding compound in de-gassing chamber after lots of stirring and scraping the sides and bottom for a uniform blending. Material is best measured by weight on a triple-beam scale. I changed to higher quality platinum-cure silicone for these latest molds.




It took a while but I finally got a quality NOS part for the left-hand lens master that was as beautiful as the right-hand lens I already had.




For the very best results I pressure cast the molds as well as the final parts. This pressure crushes any air bubbles remaining in the silicone compound. To keep from crushing the lens while under pressure you have to drill a small hole in the splitter board to equalize the pressure on both sides while it's under pressure.



Here I've sealed the part line on a splitter board to begin making a mold. I use small scrap pieces of laminate flooring for my splitter boards.



Mold box now built and sealed around master plug. Box is pressed wood sealed in Mylar film as a release surface. Seams are sealed with clay or hot glue to keep silicone from escaping before it cures.



Ready for pour. Rubber bands help hold the box together as well as hold it tightly to the splitter board. Silicone compound required for one mold is about $45 so you don't want it leaking out. 16 ounces required for first half.



First half removed from box and splitter board. I did not take pictures of pour process because you have very little working time between mixing, de-gassing, very slow pouring (to prevent bubbles) and then getting it all in the pressure chamber without spilling it before it gels. I pressure chamber cure for 24 hours @ 60 psi and then full cure the mold after that for 12 hours at 150F. I bought a small convection oven from a garage sale and rewired the heating elements in series and also modified the thermostat to get a good lower temperature range oven for curing.



Earlier test mold made with cheaper silicone. Removing all the air bubbles is troublesome. New molds are being made with an updated parting line to help "burp" the air more easily. This mold was good as a test and for learning the process. I could probably make acceptable lenses with this mold but I'm picky and want them to look best if I'm going to sell them.



Here are the sample results of testing three types of epoxies and some faint tints for fun. I'm perfecting my pouring and pressure casting skills. When it comes to "water clear" epoxies the choices are limited when you need good UV protection, impact protection and no heat warping. You also dance around a little with the pot life and viscosities of the products. I heat the molds to 140F just before a pour to help the liquid flow and to also be sure it reaches the right cure temperature in the thinner areas. Pour too fast and you trap air. Pour too slow and the epoxy gels while you are pouring. After pouring it is a must to get it into a pressure chamber quickly so you can compress remaining air bubble so small that they can't be seen.


Dave W. / Gilbert Arizona
66 Corsa 140 4-speed w/factory A/C
66 Corsa 140 4-speed w/factory A/C
66 Corsa 140 4-speed
65 Corsa 140 4-speed
66 Corsa 455 Toronado V8
65 Monza 455 Toronado V8
65 Monza 4DR 140 PG w/factory A/C
65 Monza 4DR EJ20T w/5-speed


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Re: Creating Clear LM Front Turn Signal Directional Lenses
Posted by: cad-kid ()
Date: May 27, 2016 02:26PM

Thanks for sharing the details of this interesting project. Cool stuff thumbs up

Jeremy (cad-kid)
Kronenwetter, WI (Central Wisconsin)
CORSA Member#031129
SOLD-9-2016 65 Monza 4spd/140
My 65 Monza thread
My YouTube page yawning smiley

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Re: Creating Clear LM Front Turn Signal Directional Lenses
Posted by: 2ragtops ()
Date: May 27, 2016 02:30PM

Dave

Is that the left hand lens I sold you?

Bob Bauer

Show-Me Corvairs

1966 Monza Convert 140 P/G with A/C, plastic wheel with tele-column am-fm posi-traction
1966 Corsa Convert 180 wood wheel tele-column am-fm sport steering posi-traction
1965 Corsa Coupe Crown V8 mounted mid-body temporarily red lined for repair
House Springs, Missouri

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Re: Creating Clear LM Front Turn Signal Directional Lenses
Posted by: azdave ()
Date: May 27, 2016 02:49PM

2ragtops Wrote:
-------------------------------------------------------
> Is that the left hand lens I sold you?

Yup. If you look closely you'll see a very slight mod I did to the master(s) during my learning period that made a huge difference in getting the bubbles out during the epoxy filling. Most people would not notice the mod and you certainly can't see it when the lens is in use.

Thanks!


Dave W. / Gilbert Arizona
66 Corsa 140 4-speed w/factory A/C
66 Corsa 140 4-speed w/factory A/C
66 Corsa 140 4-speed
65 Corsa 140 4-speed
66 Corsa 455 Toronado V8
65 Monza 455 Toronado V8
65 Monza 4DR 140 PG w/factory A/C
65 Monza 4DR EJ20T w/5-speed


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Re: Creating Clear LM Front Turn Signal Directional Lenses
Posted by: ROD ()
Date: May 27, 2016 05:19PM

well done !

Rod Tetrault
El Cajon , CA
65 Corsa Yenko Clone / 65 Corsa EO Creampuff Vert
66 Corsa "JIMISH" Mid engine Turbo LS1 currently 2nd fastest Corvair in the USA
Class 5 Corvair powered Baja
61 Vintage Rampy
Corvair powered Buggy x 3
Enough hidden parts to build a space ship

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Re: Creating Clear LM Front Turn Signal Directional Lenses
Posted by: ihscomputers ()
Date: May 27, 2016 06:46PM

Vairy cool process! thumbs up

Dean F. Gemberling
Columbus, Georgia


1963 Rampside V8 - YELLOW - Built by Ken Arnold in 1998

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Re: Creating Clear LM Front Turn Signal Directional Lenses
Posted by: 2ragtops ()
Date: May 27, 2016 07:59PM

and what will the lenses be selling for................I have a use for two of them


Maybe I should have demanded royalty rights on that lens.LOL

Bob Bauer

Show-Me Corvairs

1966 Monza Convert 140 P/G with A/C, plastic wheel with tele-column am-fm posi-traction
1966 Corsa Convert 180 wood wheel tele-column am-fm sport steering posi-traction
1965 Corsa Coupe Crown V8 mounted mid-body temporarily red lined for repair
House Springs, Missouri

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Re: Creating Clear LM Front Turn Signal Directional Lenses
Posted by: Dan ()
Date: May 27, 2016 08:12PM

Fantastic job! They are going to be perfect.

Dan
Chandler, AZ
1966 Corsa Turbo Convertible
[corvaircenter.com]

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Re: Creating Clear LM Front Turn Signal Directional Lenses
Posted by: veverlove ()
Date: May 27, 2016 11:12PM

Good job, Dave! That sounds like a very involved process. If I noticed the "mods" correctly, you hollowed out the area where the bolt/screw holes are located, yes? The prototype lenses look really nice. Always amazed at the display of enginuity from the members of this Forum. Too freakin' cool!

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Re: Creating Clear LM Front Turn Signal Directional Lenses
Posted by: Mike Stillwell ()
Date: May 28, 2016 03:13AM

Awesome home-grown production! Keep at it Dave, I'm sure many will line up for a pair.

Mike
YS-117

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Re: Creating Clear LM Front Turn Signal Directional Lenses
Posted by: Mel ()
Date: May 28, 2016 04:32AM

thumbs up

Orangeville, Ontario. CANADA

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Re: Creating Clear LM Front Turn Signal Directional Lenses
Posted by: coleslaw31 ()
Date: May 28, 2016 07:28AM

I asked about someone doing these before. That is awesome would love them on my 68. Any way you'll be taking orders!?

South Carolina Upstate



68 Monza convertible 140 4spd A/C (coming soon)
66 Corsa coupe 140 4spd

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Re: Creating Clear LM Front Turn Signal Directional Lenses
Posted by: quorvair ()
Date: May 30, 2016 04:22AM

Kudos Dave..!!

Very Impressive task...with perfect results.

Daniel Vallée
1965 Monza Convertible 140PG
1961 Rampside 140PG
Salaberry-de-Valleyfield, Québec, CANADA

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Re: Creating Clear LM Front Turn Signal Directional Lenses
Posted by: azdave ()
Date: May 31, 2016 02:01PM

veverlove Wrote:
-------------------------------------------------------
> If I noticed the "mods" correctly, you
> hollowed out the area where the bolt/screw holes
> are located, yes?


No. What I did was remove the very tiny ridge that outlines the gasket sealing surface on the rear face. It won’t change the function of the lens sealing to the foam gasket but that small ridge was an easy place to trap air bubbles.

Thanks for the support from everyone. To those with interest in buying, I am not taking orders yet but it looks like at least 10 people are interested. I know these will have limited appeal because they are just for late models and it’s a custom feature in the US rather than a necessity like in Sweden. I would rather not think of selling hundreds of them anyway as they are a bit too labor intensive for high volume sales.

I completed the left hand lens mold over the weekend and it looks like a keeper. It is post cured, de-flashed and I added the fill and vent sprues last night.

Just before bed I cast the first left hand lens and it is currently curing in the pressure pot. You never know if the mold might have a hidden defect until you pull the first part that was cast under pressure. I'll know if a few hours.

One thing I discovered is that even with vacuum degassing I'm still getting some bubbles when I pour into the mold. I have to count on the pressure pot to compress them to where they aren't easily seen. Next time I pour I have an idea to drain the epoxy cup from the bottom and maybe stop a few bubbles from entering the fill sprue.

More to come soon.


Dave W. / Gilbert Arizona
66 Corsa 140 4-speed w/factory A/C
66 Corsa 140 4-speed w/factory A/C
66 Corsa 140 4-speed
65 Corsa 140 4-speed
66 Corsa 455 Toronado V8
65 Monza 455 Toronado V8
65 Monza 4DR 140 PG w/factory A/C
65 Monza 4DR EJ20T w/5-speed


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Re: Creating Clear LM Front Turn Signal Directional Lenses
Posted by: Dneprdude ()
Date: May 31, 2016 02:27PM

I used to be a moldmaker and special effects guy in LA before I moved back east. Really nice job on those. We had a vacuum machine at the shop that would suck every bit of air out of the silicone before we poured. Was better than standing on a chair and slowly pouring off the bubbles.

Have you tried any Silicones Inc. products or any from Smooth-On. They both have great products and support. They have some great pourable plastics and dyes as well. Good luck withe moldmaking.

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Re: Creating Clear LM Front Turn Signal Directional Lenses
Posted by: texasuk ()
Date: May 31, 2016 03:36PM

This is phenomenal work, well done.

Do other car model enthusiasts have the kind of skills that have been shown on this forum for creating parts like this? I hope there are new young people coming through that have these kind of skills and commitment.

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Re: Creating Clear LM Front Turn Signal Directional Lenses
Posted by: azdave ()
Date: May 31, 2016 03:48PM

Dneprdude Wrote:
-------------------------------------------------------

> Have you tried any Silicones Inc. products or any
> from Smooth-On. They both have great products and
> support. They have some great pourable plastics
> and dyes as well. Good luck withe mold making.

I started with Smooth-On's tin-cure RTV and now moved to platinum-cure for the recent molds. I'm fortunate to have a mold making supply company near me so I get fresh product without shipping costs. This stuff also doesn't store well so once you open a container you have to use it up or it's wasted. sad smiley I even have a modified mini-fridge to keep my supplies at 73F because the garage gets pretty warm this time of year. A few of the epoxies require respirators so none of this stuff goes in the house or into the good refrigerator.

For water-clear resins I've used several Smooth-On products was well as Aluma-Lite and Hapco.

Tinting is very tricky to get repeatable results. In the beginning, I will only offer clear lenses and then maybe a light smoke tint or a very, very light hint of blue to hide the slight yellow tint of some of the epoxies. When you heat cure them they become more durable but also will very slightly yellow with some brands of epoxy. In the photo below, the middle lens has a slight blue tint. Not really obvious unless it is next to a fully clear lens.

I've spent way more than I thought I would to learn the skills and products but I'm sticking with my goal to never make money on my hobbies. grinning smiley




Dave W. / Gilbert Arizona
66 Corsa 140 4-speed w/factory A/C
66 Corsa 140 4-speed w/factory A/C
66 Corsa 140 4-speed
65 Corsa 140 4-speed
66 Corsa 455 Toronado V8
65 Monza 455 Toronado V8
65 Monza 4DR 140 PG w/factory A/C
65 Monza 4DR EJ20T w/5-speed


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Re: Creating Clear LM Front Turn Signal Directional Lenses
Posted by: Dneprdude ()
Date: May 31, 2016 05:26PM

It's definitely expensive experimenting with these fun chemicals. I was lucky to use them in school and at work occasionally before I began doing stuff on my own.

We used to make a lot of bodies for CSI and NCIS with the clear GI 1000. We would cast a body from a fiberglass mold, shave it down 1/4 -1/2" or so except for the keys, place it back in the mold and pump gallons of tinted and flocked silicone back into the mold. In the end it would cost about $1000 for a body. We would fab on different heads for different scenes or shows until it started to wear out. It was fun until someone didn't mix the kicker in a batch. Then we got in trouble.

Ive been using a of the Smooth-On brush up silicone and making matrix or mother molds. I like this route because it's been reasonably cheaper, especially for making only a few copies. Look forward to reading more posts. Maybe I'll fiddle around with some parts this summer when I get some time off.

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Re: Creating Clear LM Front Turn Signal Directional Lenses
Posted by: azdave ()
Date: June 01, 2016 07:33AM

Pulled the first LH lens out last night. One small bubble but still improving the pour technique. Mold worked great and no damage from removal.




Dave W. / Gilbert Arizona
66 Corsa 140 4-speed w/factory A/C
66 Corsa 140 4-speed w/factory A/C
66 Corsa 140 4-speed
65 Corsa 140 4-speed
66 Corsa 455 Toronado V8
65 Monza 455 Toronado V8
65 Monza 4DR 140 PG w/factory A/C
65 Monza 4DR EJ20T w/5-speed


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Re: Creating Clear LM Front Turn Signal Directional Lenses
Posted by: thewolfe ()
Date: June 01, 2016 07:58AM

Those look fantastic!


Nate Wolfe
Portland OR
65 Corsa 180

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