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Prototype G20 (T17) Lampholder

Prototype G20 (T17) Lampholder

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Still sorta a work in progress at the moment but here's a prototype of a reproduction G20 mogul bipin lampholder that's used with T17 fluorescent lamps. The design is based heavily off the GE one I already had. I made some assumptions about how the interior was since I didn't want to take apart the GE lampholder as the cardboard back is held on tightly by 4 press in pins. I still need to do some minor tweaks to finalize the design. I have the inside contacts designed to but I haven't made a prototype of those yet, the same applies to the mounting bracket that the real ones used.

The prototype is 3D printed using PLA, I do not recommend actually using a PLA print in actual service as PLA has a fairly low melting point and issues with fire retardance to be safe for use with a actual lamp.

COL_20180809_210020~0.jpg 20180618_174203.jpg 20180618_174742.jpg 20180618_175848.jpg

Light Information

Light Information

Manufacturer:Original: GE Co | Prototype: 347v Electric
Lamp
Lamp Type:T17
Base:G20 Mogul bipin
Physical/Production
Fabrication Date:1940s-1950s | August 2018
Application/Use:Light socket | Non functional prototype

File information

File information

Download: Download this File
Filename:COL_20180809_210020~0.jpg
Album name:joseph_125 / Miscellaneous/Lighting Elsewhere
Keywords:Gear
File Size:207 KB
Date added:Aug 09, 2018
Dimensions:1080 x 1215 pixels
Displayed:92 times
Date Time:2018:08:09 21:07:12
DateTime Original:2018:08:09 21:00:20
Exposure Bias:0 EV
Exposure Time:1/24 sec
FNumber:f 1.8
Flash:No Flash
Focal length:4.42 mm
ISO:250
Make:LG Electronics
Model:LG-H831
White Balance:0
URL:https://www.lighting-gallery.net/gallery/displayimage.php?pos=-149530
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Lumex120
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105555521242365640724 UCM30tBQDUECOV6VeG5W87Vg
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Aug 09, 2018 at 07:51 PM Author: Lumex120
I have been waiting for someone to do this. I would suggest trying to print it in ABS, it has a higher melting temperature and it's a lot stronger.

LEDs = Downgrade 99% of the applications.

joseph_125
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GoL
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Aug 09, 2018 at 08:02 PM Author: joseph_125
Yeah ABS has the advantage of being stronger and has a higher glass transition temperature but I would at the bare minimum use flame retardant ABS. Regular ABS burns rather violently even with the flame retardant stuff I would probably do a burn and arcing test before I would actually use it in the fixture. Personally I would injection mold them out of bakelite or urea-formaldehyde, two plastics that are commonly used to make electrical devices.

I got all of the dimensions from the existing socket using a pair of calipers so the dimensions should be fairly accurate to the real thing. Now to find a T17 starter socket to reverse engineer...
xmaslightguy
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^homebuilt fixture


GoL ATL
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Aug 09, 2018 at 08:20 PM Author: xmaslightguy
I've thought it would be cool to do this, but wondered how well it'd hold up.

From a guy I've met on one of the Christmas Light forums who has a 3D printer (has even brought it to a meetup & demonstrated it in action).. and has test printed stuff for outdoor use:
PLA will also shrink/warp when exposed to heat - like sunlight shining on it & getting it hot (ABS will as well, but to a lesser extent, ABS also has better UV resistance).

I have a feeling that as time goes along, things will get better with 3D printers and you'll eventually be able to 'print' in some sorta high-temperature and/or high-strength plastic. (actually I also see it as only a matter of time before someone figures out how to do a consumer-level 3D metal printer too)

Colored Fluorescent's such as F40T12 Red or  Green or Blue are awesome...

Lumex120
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Aug 09, 2018 at 08:22 PM Author: Lumex120
Wow, I had no idea ABS was that flammable. I have burned PLA and a few other materials and they are flammable but not that badly. I have done small arcing tests with a CCFL inverter and it hasn't ignited plastic to the point of combustion. That was with PETG and PLA though.

LEDs = Downgrade 99% of the applications.

Lightingguy1994
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Aug 09, 2018 at 10:10 PM Author: Lightingguy1994
Great job here! this is the kind of thing I hope to start doing someday when safer plastics are more common.
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Aug 09, 2018 at 10:29 PM Author: DimBulb
Nice!!!!
Making some that are the same shape as T12 lampholders would be cool too.
A bit easier to mount in a custom fixture.

My very first word was LIGHT!

joseph_125
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GoL
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Aug 10, 2018 at 12:16 PM Author: joseph_125
Thanks, yeah if there was something more flame retardant and heat resistant I could make a functonal version of this prototype shell.
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Zack


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Aug 11, 2018 at 09:16 AM Author: Fluorescent05
Nice!

Don't be fooLED, T8 IS the worst thing to do to a magnetic T12 fixture.

streetlight98
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Mike McCann


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Aug 11, 2018 at 01:20 PM Author: streetlight98
Wow really cool! Looks almost exactly the same!

#167

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Zack


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Aug 11, 2018 at 02:52 PM Author: Fluorescent05
Do you have a T17 to test fit with?

Don't be fooLED, T8 IS the worst thing to do to a magnetic T12 fixture.

joseph_125
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GoL
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Aug 11, 2018 at 11:11 PM Author: joseph_125
Thanks. I don't have a T17 to test fit but the method I used to obtain all the critical dimensions should mean a T17 will fit.
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Aug 12, 2018 at 08:18 AM Author: DieselNut
That is cool! You will have to remove that backing in order to get the lamp contacts in place. They slide in through the back and are held in place by their shape and their fit with the socket shape, then the back is put on to keep them from sliding out.

Preheat Fluorescents forever!
I love diesel engines, rural/farm life and vintage lighting!

joseph_125
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GoL
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Aug 12, 2018 at 08:14 PM Author: joseph_125
Thanks, yeah the backing is removable to install the lamp contacts. I designed slots for the contacts to sit in like the originals.
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