DanSavage

Todd,

YW.

There are two methods of printing metal parts.

The first, used for brass, bronze and silver is lost wax casting. The part is printed using a printer that prints wax. This wax part is then encased in plaster and the wax is melted out. The cavity is filled with molten brass, bronze or silver.

The second way, used for the steel parts is infusion. That process is shown in the second video I posted. Basically, the part is printed by a printer spraying resin onto steel powder layer by layer. The resin is cured, layer by layer. Once the printing process is complete, the resin binding the part is cured in a low-temp oven. Once that is done, the part is removed from the steel powder and goes through a third step where bronze powder is melted in a high-temp oven and gets sucked into the printed part like a sponge soaks up water. The resulting part is a blend of bronze and stainless steel.

I have had steel bushings for another project printed by Shapeways and the final parts resembled polished sintered steel. In the end I decided not to use these because my needs were for very tight tolerance parts which could not be met by this process.

Here's some examples of stainless steel printed parts:

DanSavage

Hi Dave,

Thanks for the suggestion.

Molding the new parts might work once I've finalized the design as they would probably be a lot cheaper than printing them.

I don't think molding the OEM **** would be a good idea because they require the teeny-tiny spring (shown earlier in the thread) to grip onto the dimmer prongs. Without this spring, the **** slips off the prongs pretty easily.

The recess in the **** I'm designing will fit the prongs pretty tightly and will grab onto the notches in the prongs so no extra parts will be required.

The only hitch is whether the silicon molding material can duplicate the shape of the recess and can release from the undercut in the recess of the final molded part. If you're interested I'll post a pic of the 3D part showing what the new recess looks like and you can tell me if molding this is possible.

Making rigid molds wouldn't work because they would not be able to release from the undercut. But, if the silicon mold can be squeezed out of the recess without damage to the mold, then molding these parts might be workable.

FWIW, the recess is about 3/32" thick x 1/4" wide x 5/16" deep.

Dan

bleeper

3d printing is cool stuff

Lee DeRaud

Typo? That 5/16" depth number sounds way off: I doubt the whole **** is that thick.
(I don't have mine handy to measure at the moment... )

DanSavage

Oopsie. Not a typo --a WAG.

I measured it and the recess is 3/16" deep.

What happened to yours? (heh heh heh...)

Dave68

Dan,
As you know, the greater the undercut, the softer the silicone must be, and the higher the part dimensions tolerances. It may be worth a try, as the silicone I currently have is fairly soft. (Shore A 20)
Once you verify that it works, I can always buy one from you and experiment if it looks doable.

DanSavage

Sounds good.

Once I get a workable design I'm planning to order 10 or 20, so I'll send one to you to play with.

As I said earlier, I've ordered a couple of the latest design, so now I'm just waiting for them to be printed and mailed. They should be here around the 20th or so.

Lee DeRaud

FWIW, my best guess from looking at the original is that the back cavity insert is injection molded and then the button itself is overmolded from some softer material. That bypasses the worst of the undercut issues and makes it trivial to use different-shaped buttons on the same switch post.

j3studio

Very cool discussion and part of our future, methinks ...

DanSavage

You're correct. The OEM **** is a two-piece affair. The **** is one piece with a square-ish recess and the part that rides on the prongs is inserted into this recess.

They both feel to me like they're some sort of ABS or styrene. IOW, the **** itself is not a soft rubber, but a hard textured plastic.

I agree with you. This **** is probably a common GM part that can be used for applications in several cars by using a different insert.

DanSavage

Thanks! Not your usual automotive discussion, is it?

Actually, once I'm done with this ****, I'll be on the prowl for other hard-to-find parts I can make.

DanSavage

Great news!

I got the latest version of the HUD **** back from the 3D printers and the recess fits the prongs perfectly.

It snaps solidly into place and stays there until it's intentionally removed and it's easy to snap off without damage to the prongs.

I actually ordered two different materials. The one delivered today was the frosted ultra detail. I'm expecting to get the other one tomorrow, which is the white nylon.

I tested painting my previous **** (white nylon) and the new one (frosted ultra detail) with gloss black paint to get an idea of how closely both match the OEM surface texture.

The rougher surface of the white nylon is a much better match for the original ****, so as long as the one being delivered tomorrow fits the prongs, then that's what I'll be going with.

I did find one minor discrepency. The recess in the **** is just a little offset from the OEM **** which pushes the **** a little bit further to the right. (~1/64" or .0156") I normally wouldn't sweat this minor difference, but I don't want the ***** scraping on the side of the HUD control unit. So, I've moved the hole to eliminate any chance of it rubbing.

Here's some pics:

Here's the latest **** with the updated recess.


Here's the painted white nylon next to the OEM ****. As you can see, the surface texture is pretty close. This **** has different proportions than the OEM ****. This has been fixed in later versions.



Here's the OEM **** on the dimmer.





Here's the **** I got today with the new recess next to the OEM ****. As you can see, the outline is much closer to the OEM ****.

TOP:


As you can also see, the recess is slightly offset from where it should be.

BOTTOM:


Here's the new unpainted frosted ultra detail **** on the dimmer.



Here's a (blurry) shot of the painted white nylon **** on the HUD. I just wanted to get an idea of how it looked compared to the OEM ****.



Here's the painted frosted ultra detail ****. I really don't like the smooth texture. It looks out of place. But, the shape is right.

Lee DeRaud

IMHO, getting the color/gloss right probably matters more than the surface texture: there are a gazillion shades of "black".

mre1974

WOW you're making impressive progress. From the looks of it I'd be all sorts of content with the translucent one you have...that would just be kind of cool and different. IF you ever want a guinea pig/volunteer to give it a "real world daily test" let me know...I'll be happy to try one and get you feedback.

DanSavage

True, but I personally would prefer to have the surface text be a close match the surrounding area, which is kind of a sand-blasted appearance.

You're right about shades of black. On the surface it sounds like black is black, but in reality black is a blend of all other colors of paint and it can sometimes take a tinge of one hue or the other.

What what I see so far, a semi-gloss black on the white nylon **** would be an almost perfect match for the OEM ****, so that's the way I'm leaning.

I used Tamiya acrylic enamel model paint on these *****, which has extremely finely ground pigments and results in a high gloss, even in the thin coats I applied.

Rustoleum Never-Rust black spray paint dries to a semi-gloss finish, so that's what I'll try on the white nylon **** I'm getting in today.

As soon as I've been able to confirm the fit of the recess in the white nylon and by how much the recess should be moved, I'll order the final version.

DanSavage

Thanks! Yes, the translucent one would work just fine. It snaps on and from the feel of how it snaps on, would probably last the life of the vehicle. I'm just being a little **** about the fit so that once it's done I won't have to modify the model again and can feel good about sending out something I can be happy with.

I'll keep you in mind.

DanSavage

I got the white nylon **** yesterday and it fits the prongs as well as the translucent one, so I'm happy with it.

At first the fit was a little squishy, but then as I looked into the recess I saw some excess powder from the printing process was stuck in the corners. I used an Xacto knife to scrape it out and now it snaps on and off really well. In fact, I've got it on my HUD dimmer right now and I'm going to leave it on for the time being.

I'm still not happy with the painted finish, though. I tried painting it with Rustoleum, but it's still too glossy.

I've ordered a couple more of the final style and when they come in I'll be playing with different finishes.

Ron71

Looks good. For what it is worth, I think the SEM satin black paint should be really close to a factory color match.

Lee DeRaud

That area, like the radio and the A/C, looks more like a dark gray to me.

But at least there are only 50 shades of that. <rimshot>

DanSavage

Thanks and thanks for the suggestion. I checked around and no one sells SEM paint around these parts. (naturally!)

So, I'm going to try to get some Duplicolor satin black trim paint and some Rustoleum semi-gloss paint and test them this weekend.