Thermoforming Acrylic panels.

[jackpilot]

Actually it was easy.
I followed precise instructions from Steve Cos and it worked out fine.
I made an MDF form replicating the TQ curve. Attached the panel with 2 screws at the bottom and " slowly warm it up, working  the heat from the screws to the opposite end.  Slowly pushing the panel down. "
Heat gun at low setting, not closer than 6", circular motion.
You have to be very patient and do it SLOWLY.

[ETomlin]

Thank you very much! I shared this with our Learjet builder's group at Hangar 45.

[Trevor Hale]

Beautiful...  Looks great Jack..  Man, I can;t wait to see this thing finished.

[jackpilot]

Man, I can;t wait to see this thing finished.

So do I..You have no idea!!!

[MarkDidIt]

Curious if you did the warming and bending after you had painted and engraved (Looks engraved)?

I have to do this same thing but was worried about cracking or peeling of paint during this process.

[jackpilot]

Hi "Mark"?

Those are  FDS Pro backlightable engraved panels .
As long as you do it gently and slowly no prob at all with the outer surface.
Avoid overheating which can cause warping and bubbles. (heat gun too close)
Bending a panel like the one shown takes about 15- 20 mn of gentle circular motion to heat evenly.
Jack

[MarkDidIt]

Thanks, It sounds like I should be able to do this as well then.  I already have the form built.  My TQ cover is for a Learjet 45, it's considerably wider and I made the panel myself (also backlit) with Cast Acrylic using my CNC machine.  Because of the width, I'll have to make sure I take my time with it.

ETomlin had posted a link about your success over on the Hangar 45 board, so I had to pop in and check this out.

I'll give it a shot and let you know how it worked out for me.

FYI: Here's a pic of the TQ levers I built from scratch for it:


Mark

[Bob Reed]

Hey Mark, those look great! Thanks for sharing that with us.

[jackpilot]

Mark
Try on a sample to find out the right distance for the heat gun and get he hang of it.
PS: Nice TQ

[ETomlin]

Yes, thanks again Jack. Mark did a great job on his LJ45 levers. If I didnt have a real set, I'd for sure be buying some from him! His look extremely close to those of us fortunate enough to have a real set. In fact, Ron and I both have said several times that when we look at Mark's lever set we forget they are CNC built!

I appreciate you passing along the info on the process for making the curved part and it's what I suspected all along on how to do it but in all honesty I didnt know that the secret was to take as long as you are advising. You have really helped us Learjet guys out with sharing the tecnique and from the Hangar 45 crew, thanks! Im excited to see how it works out for us.

[MarkDidIt]

Here's an update on my attempt to form my TQ cover this past weekend.

Due to the different thicknesses of the material, what I feared would happen did.  The very thin part where the back was milled out for the backlighting, sagged on me and no way to correct it.  The problem is getting enough heat for the .25" material to allow it to be formed, but was too much the other area that was only .050" thick.  So I have to find another way to solve this.  I have a couple options in mind, but here's how it turned out anyway.

Newly CNC'd cover, ready for forming:


Backside milled out:


Jig setup which is my first version of the TQ console.
(I cut slots to help distribute the heat which worked as planned).
You can see the bullet heater on the left to force very hot air in thru the side of the jig:







Fullsize: http://www.markdidit.com/Project45/throttle/IMG_6733.jpg



Secured and cooling down

[jackpilot]

Not sure you can make it with the diff thickness.
I heated mine from the top (painted side) extremely slowly with a heat gun at low setting with circular motion working the heat up the panel while bending.
But they were 3mm even panels.

[Boeing Skunk Works]

The older Boeing throttles are constructed a bit differently than todays models. Each piece from the left side to the right side of the throttle housing was individual pieces of formed or stamped aluminum. My covering is all individual strips of laminated plastic, rubber, and aluminum.

When I was trying to get the first layer of plastic to conform to the throttle bulkheads, I cut the covering strips to the width I needed but left a little length on them. I set the oven on 125° and put the bulkhead with the strip balanced on the top in the oven and let it form itself. This was polystyrene though and it melts quite fast at low temps.

I don't know if that method would work with different thicknesses of acrylic though.

[Trevor Hale]

Just a thought here guys, and I wouldn't recommend doing this when the wife was around, but what if you places the plastic on a cookie sheet in the oven, and warmed it up gradually and then laid it on the throttle so it would just slack over the throttle?

Would this prevent those thin areas from creasing and allow uniform bending because it is done all at once?

Trev

[Boeing Skunk Works]

Teflon is not just for cookies anymore!

Might work if you can get it off of the cookie sheet at one go.

[jackpilot]

I tried the oven.
300F 7 mn     too short
350   10mn    too long or too hot, the sample was warped
Pretty sure can be done if the proper F/mn can be found
Note:the paint was not affected in both cases.

[Rob65]

The oven should work.
I've seen professional vacuum forming machines that have a ceramic heater to heat sheets of acrylic or other plastics and wood.

Most acrylic I've used must be heated up to 160 C (320 F). The time is not that critical, it must be long enough for the heat to spread through the material.
I think this works for different thickness also but you have to use a negative mold just to make sure that the thinner parts are not pushed inwards.

heat up the sheet in the oven and the mold with a hot air gun (to make sure that the acrylic sheet does not cool down too fast) and use vacuum to press the acrylic into the mold. Place something like a cotton cleaning cloth on the inside of the mold before applying a vacuum bag to be used as a transport medium for the vacuum.

At least that's the theory - I have not mastered the technique of vacuum forming acrylic myself but I am investigating how this must be done.

Rob

P.s: just do this while the wife is around. She can then use the pre-heated oven to make a delicious cake 

[Trevor Hale]

just do this while the wife is around. She can then use the pre-heated oven to make a delicious cake 

Then she will feed the poisoned cake to you for doing it.

[autocadplease]

TAP Plastics has some videos on bending plastic http://www.tapplastics.com/info/video.php

[hexpope]

Thanks for posting this, I was  wondering what I was going to do when it came to the plates of my throttle quad.  Ill give it ago with 3mm aryclic and see how it turns out.

[NeoMorph]

The way I did it in the past was attach a weight on the one end (I used a diving weight as that is what I had available at the time).

I remember getting micro fractures in some of my bends but cannot remember what I did to remedy it. Anyone know what I mean?

[hexpope]

nope Neo, I hope I dont come across that when doing it, but 3mm should be super easy to work with (I hope!)

[NeoMorph]

I have a feeling I was using 6mm (or maybe a bit thicker)  and was actually making a base for a router at the time. It was thicker to allow me to fit countersunk screws underneath. Instead of it bending cleanly it went all weird and sparkly inside the plastic. Maybe not enough heat + too thick perspex.

This was a few years back now so my memory sucks... I just hope that when I get around to doing my throttle quadrant covers that I can get it right first time.

[hexpope]

Just an update. I used the oven method. (160 C ) when the panels were painted and engraved. Worked really well. I was using 3mm acrylic. Having the shape ready for it when it comes out of the oven is a must. I couldn't believe how fast it cools when removed from the oven. I also thought that the engraving would warp or the paint would be all sticky, but it was not.

Thanks for the tips.

[jonesthesoftware]

Hi Guys
just like to add my opinions to this thread
Don't use acrylic--- use HIPS (high impact polystyrene) sheet. It has several advantages
1 it's more flexible than acrylic, you can even bend it around your THQ with no heat and no cracking, but obviously it will try to return to it's original shape.
2 it has a lower melting point, so you can warm it with less heat I used a hair drier.
3 it is "whiter" than acrylic so that when you engrave through the paint your legends show up better even without the backlighting.
It's available in sheet form just like acrylic, but ensure you buy High impact polystyrene and not polystyrene packing foam.
Only disadvantage is paint does not stick to it as easy as acrylic. With Acrylic I didn't even use primer but with HIPS I had to use plastic primer. Not much of a problem. I engraved then painted then heated and bent no problem.
You can see the results in the attached image of my 767 throttle i've just made
regards
geoff