License light lens

[JFENG]

Guys,
I am trying to learn how to make plastic molded parts. My very first project was the 73 and earlier license light lens.
My process still needs a 2nd round of tweaking, but I was able to produce 3 usable lens which I don't need (I'm keeping 2 for myself). The material is a clear, UV resistant urethane plastic that has max deflection temp rating of 176F (for stability in proximity to a incandescent bulb). I thought that was sufficient but no doubt there are higher temp rated urethanes out there.

I don't know what they are worth to you guys, so offers invited.
I need a second chrome cover and am interested in trades.


John (MA)

(details)
They are the right shape and include the PN and raised Hella logo in good/sharp detail. They are all flawed in that each one has one bubble in the rear "domed" part of the lens. There are also a few micro-bubbles scattered about because I didn't leave the mixed resin in a vacuum chamber long enough to pull all of the air away from the injection nozzle. Hey, my eye sight isn't as good as it was when I was young! I LOOKED ok to me and yes I was wearing my reader glasses.

Anway, this little piece has some deep and complex contours given the thickness of the piece, and the plastic flowing into the mold is trapping one notable air bubble back there (3mm diam.). This is due to my inexperience designing the injection/vent holes. This is completely invisible with the lens installed in the chromed cover. Based on what I learned, I'm sure I can make a new mold with different venting/injection points and make a flawless part. But I'm not sure if it's worth the time and effort given that these 1st parts look perfect once installed.

Note, in the pics, I've not cleaned the mold flash off around the edges of the parts (will be done). But nevertheless they fit perfectly in the OEM housing.

Here's some pictures of a used OEM and some repro parts. If you polish up the repro with some car wax, it'll gloss up nicely. It does not have the exact same refractive index as the original lenses.

 

[Markos]

Hi John,

Great job! If your process permits and you have vent holes, ou can vibrate the bubbles out of your parts. When I did my concrete countertops last sunmer, I sacrificed a back massager to get the bubbles to rise out of the mold. Your parts are obviously way more complex but it is worth considering if you are still getting bubbles in the next iteration.

 

[JFENG]

Markos,

We did try some vibration but the thinness of the part, the fact that that rear dome area is almost horizontal relative to how I was holding the mold, and the slightly higher than water viscosity of the resin ... that damn bubble was just not going to come out from that deep inside the mold.

The mold does require vent holes. If I do it again. I'll put the injection and vent holes at the two opposite long ends and inject from below. This will reduce the distance the resin has to flow and also push air up out the vent. I don't know why I didn't think of this the first time. Not to bright, but the important thing is to learn from one's stupidity. It means I'll need a way to ensure the syringe plunger doesn't back-off and draw air back into the have to leave the resin bottle stuck in the mold until the material starts to setup or sacrifice the syringe each time (I put the whole thing in an oven to speed up the 4 cure time). Or maybe I could pull the syringe and plug it fast enough to avoid letting a bubble in. If this were setup for real mfg, the mold would have a shutoff so I could squirt, pinch and remove the resin syringe. But then I'm not trying to make a run of 100 of these things.

John

 

[Markos]

I’m thoroughly impressed, nothing “stupid” about the first run IMO. Good that we are hard on ourselves though!

 

[Tony.dreamer]

Markos,

We did try some vibration but the thinness of the part, the fact that that rear dome area is almost horizontal relative to how I was holding the mold, and the slightly higher than water viscosity of the resin ... that damn bubble was just not going to come out from that deep inside the mold.

The mold does require vent holes. If I do it again. I'll put the injection and vent holes at the two opposite long ends and inject from below. This will reduce the distance the resin has to flow and also push air up out the vent. I don't know why I didn't think of this the first time. Not to bright, but the important thing is to learn from one's stupidity. It means I'll need a way to ensure the syringe plunger doesn't back-off and draw air back into the have to leave the resin bottle stuck in the mold until the material starts to setup or sacrifice the syringe each time (I put the whole thing in an oven to speed up the 4 cure time). Or maybe I could pull the syringe and plug it fast enough to avoid letting a bubble in. If this were setup for real mfg, the mold would have a shutoff so I could squirt, pinch and remove the resin syringe. But then I'm not trying to make a run of 100 of these things.

John

Amazing work John,
I am impressed! Congratulations!
I am sure your next runs will be even better. I am curious if you were to make several sets what would it take ? How much you sell a set for?
I wouldn’t be surprised if the price is right you can sell 100 set fairly quickly!

 

[rsporsche]

John,

i will jump in with Tony + Markos, great work! i need some of these lenses. i will check to see if i still have the spare frames, i think i sent the whole spare lights to Burger

 

[Tony.dreamer]

Food for thought !
I bought a set new from W&N! It came with the lenses in them. However there are NO “Hella “ logo or marking on them. Furthermore I tried using the new lenses from W&N on the the old ones with Hella marking which I have re-chromed and to my Surprise they did NOT fit . Nit even close ...

 

[Wladek]

Food for thought !
I bought a set new from W&N! It came with the lenses in them. However there are NO “Hella “ logo or marking on them. Furthermore I tried using the new lenses from W&N on the the old ones with Hella marking which I have re-chromed and to my Surprise they did NOT fit . Nit even close ...

Because you purchased later style, completely different shape of upper part

 

[JFENG]

Because you purchased later style, completely different shape of upper part

When I searched on the Hella PN 12958r4, I found quite a few variants of different covers/lenses that span 4.5 decades.
Most look like they'd fit our bumpers. Within my very limited knowledge the chrome cover used on the E9 seem unique.

Tony, the best solution is to send me that rechromed part and use the new complete assembly from W&N

 

[rsporsche]

nice try John ... i'm guessing that your tongue was firmly planted in your cheek when you made that comment