Acrylic Part

Does anyone have an acrylic material that can make the part on the attached dwg. The original part was molded glass and was the enclosure for a light on the top of a flagstaff for a small wooden boat. Polycarbonate will not work as it is too sensitive to ultraviolet and rapidly turns yellow.

Acrylic is not at all sensitive to UV but may not work as a 3D printed part depending on the curing process. The alternative would be to machine the part from a 1.5 in. diam. clear acrylic bar and then polish both surfaces after machining using automotive buffing compounds. The original glass part had an incandescent bulb but the new part will have an LED bulb to eliminate the high temperature issue.

Your comments and suggestions would be greatly appreciated. And I can provide the file in IGES, STEP or SAT formats

Thanks very much

Bob Price
518.895.8954

Bob, this is the forum of a 3D printing service. We offer 2 types of acrylic (well 5 different products) So we have plain acrylic plastic, which you can get in White, Black or Transparent https://www.shapeways.com/materials/acrylic-plastic. The for highly detailed models we have Frosted Ultra detail and frosted extreme detail https://www.shapeways.com/materials/frosted-detail-plastic. Unfortunately, we don't accept Iges Step or SAT. But if you click on make at the top of this page, then click upload, you can upload a DAE, OBJ, STL, X3D, X3DB, X3DV, or WRL file.

OK - here are the .SAT and the .IGS files

And I have a piece of clear acrylic on its way to me from McMaster-Carr if you want to try machining it.

Thanks a bunch

Bob Price

Someone didn't read...

I seem to have a problem creating the STL file. When I issue the command I get an error msg. saying that the part is not a solid but it was created by creating the profile and then rotating it 360 deg. And I sent it to a shop in Buffalo as an IGES file and their Soldidworks created an STL from that so I am confused.

But while I work on solving that, can you talk to me about the viability of making a clear part using your 3d printing skills: can that be done and will it work in an outdoor environment?

Thanks

Bob

And I have a Planning Board meeting @ 1930 so I may not get back to you until late tomorrow morning.

You may find that you don't need an optically clear lens. If you can use a LED that is brighter than the original incandescent, then you could compensate for the refraction of the materials that Shapeways can produce.

But, I am not certain that any of the materials which Shapeways currently offers would fare well out in direct sunlight.

Acrylic anything will yellow in sunlight. Both transparent detail and Frosted Detail can be polished to be fairly translucent.

You have error in profile for rotation as solid. I fixed it and attached file (stl) and simulation of SW Frosted Detail Plastic.

WOW - thanks a bunch. I was going to redo the profile and re-rotate

That was very nice of you to do that. So now the question remains as to the UV durability of the acrylic material. One of my material data sheets states "Acrylic is inherently one of the most UV stable materials available" But being a cautious person tells me I should get a second opinion.

Bottom line, how much would in cost to make one using the best available 3D printing material?

Again, my thanks.

Just upload model to SW... 21$ in transparent acrylic. http://shpws.me/K2Be No my markup. Please check size - I am not sure in right scale in conversion.

You state "transparent" but the model seems to be translucent. Is that a limitation on the cad material presentation?

Here is a PDF with some dimensions: the only critical dimensions is the OD which has to fit the ID of the brass support ring.

The JPG shows the glued together part on the support ring.

Let's assume $5.00 for shipping. Can I pay you through PayPal or a credit card?

Bob

The process is not as uniform as you probably would like, not from batch to batch or for one individual part. Some areas on a print will be more transparent than others due to things happening in the 3D printer, such as support material that is removed, how the part is positioned during printing, and who knows what else. That means polishing will probably be required but even then there's no guarantee of uniform "transparentness" when you're done.

As far as pricing goes all you need to do is to upload a file in an acceptable format and do a check-out procedure to see what your costs might be based on material selection and shipping options. Instead of trying to make the actual full sized part right away you might be better off uploading a miniature cheaper version or test pieces in one or more materials to see how they suit your needs in terms of environmental exposures, polishing, etc.. Most materials offered here are primarily intended for making things for decorative purposes and once you start considering uses for real world applications it's a different can of worms with no guarantees about environmental effects and a limited knowledge base of existing users.

Are you trying to just make one part for a restoration effort? If so have you considered finding a local laboratory or industrial custom glass making service to fabricate a part like this to spec? Maybe a local glass blowing studio? At one point Shapeways had offered a 3D printed glass process but withdrew it for some reason (and it was very frosty, not clear as I recall). Maybe there is someone else out there who is or will soon be offering 3D printed glass. It might be worth searching for something like that.

All good comments and I appreciate them.

Yes, I would like a usable replacement part and yes, I am aware that polishing will be required. On that score, I think I can chuck the part in my lathe and, using a properly configured wooden plug, polish the ID with automotive buffing compounds up to 8000 grit to get the ID smooth and relatively clear.

Then I can mount the part on a second plug that is a push fit on the ID and polish the OD with the same buffing compound to get it as clear as possible.

And I think I mentioned that I have found an LED bulb which is a direct replacement for the BD15D bayonet mount dual contact bulb. That will be much cooler than the incandescent bulb.

And I have sent the photos and dwg. to a glass person up in NH but am concerned about the ability to make a uniform cylinder without some sort of very expensive mold.

I spent few minutes looking at the headlights on my wife's 11 yr. old RAV4: they are large pieces of some sort of very clear cast polymer but which polymer? They are exposed to sunlight, road salt, gravel, sand etc. and the clarity seems to be at least 95% of what they were when they were made.

So what do all of you kind folks think?

Ciao

Bob Price

As far as I can tell plexiglass is the most common UV resistant clear acrylic. You can purchase it from a source like this, for example: http://www.eplastics.com/Plastic/Plexiglass-Extruded-Acrylic -Rod Extruded is available in sizes up to 2 inch dia and cast up to 8 inch dia from that particular place. And they do custom work and machining so that might be the easiest path to get it done. There are probably many more places like this out there.

Processing it on a lathe shouldn't be much different than making a small bowl, except for the plastic material characteristics. Maybe a woodworker is who you need to seek out. The people who turn acrylic pens have all sorts of special high grit polishing pads and plastic polishing compounds so maybe you need a woodworker/pen maker than can polish a finish to clear glass quality.

If you aren't tied down to the exact same design maybe you could use an extruded hollow rod of the proper diameter and just print a dome to cover the top and attach with a proper adhesive. That way you would get good reliable transparency around the sides and possibly something slightly different looking on top in the dome, that might also change in appearance slightly over time. You might also have a visible seam but there would be a lot less machining and polishing to be done. I suppose it all depends on whether you are going for historical accuracy or functionality.

Good Morning Mr. Nibbles and thanks for the commentary and suggestions.

I got a piece of acrylic rod from McMaster-Carr yesterday in anticipation of getting a too expensive quotation for the custom glass part lady..

The challenge for me is getting the radius on both the inside and outside of the dome. My plan is to first bore out the ID to 1.250 and then use a large diameter drill to get a "cone" at the the top and then use a ball nosed carbide burr to create the radius. Once that is done, I can turn the OD to the 1.400 diameter. Then cut off the blank leaving plenty of stock to create the outer dome using a wooden template to get the proper radius since I do not have a radius cutting accessory for my 1942 era Pratt & Whitney 13 x 30 lathe.

Then the polishing phase using 400/600/800 grit paper & water followed by buffing compound and a wooden mandrel to reach inside the bore followed by the OD with the part held on the mandrel.

Should be fun.

But all of this is not going to happen if I can get a 3D printed part that will work and even if I have to polish it when I get it.

Cheers

Bob

Sounds like it should work. I've never turned plastics but I imagine one needs to be careful and have very sharp cutting tools. I would probably end up with a blob of molten and re-solidified mass of plastic. 3D printing is definitely the ultimate solution! Another long shot is to identify a 3D printer/material that can make something clear and use 3Dhubs to find someone willing to take a shot at printing it for you. Such a service can maybe give you access to more exotic printers that don't make financial sense for a high volume place like Shapeways to use.

Another option might be to 3D print a mold and cast a clear material into that, but I don't think common polyester resin mixes stay clear with UV exposure. I'd be tempted to also search Ebay for a salvaged replacement part. Or maybe find a jar of grape jelly in a grocery store that just happens to have the correct dimensions and cut it to size. It is an interesting project to say the least so let us know how it turns out!

If you 3D print in one of Shapeways somewhat clear materials I don't think it's going to stand up to ultraviolet light for very long.

I didn't read the entire thread so I don't know if anybody mentioned it, another option would be to make a master using 3D printing in a cheap material like Shapeways Strong and Flexible Plastic and then sand down any print lines on the inner and outer surfaces and then use that to make a mold from silicone. From there you could use a clear resin to make the final part. A good place to obtain casting resins and mold making information as well as silicone is smooth on Smooth-On. Another thing you could do along this line would be to make a mold from your glued together cover.

You might even be able to find one of these already made or perhaps you could find something like a test tube that is the same diameter and then cut it down to size using your lathe. These shapes can also be purchased as what is known as a thimble dome, from craft stores and the like. I've seen small ones before in the size you're looking for that are used to make tiny display cases for small things.

I wonder how much a glassblower would charge you to make something like this?

One other thing you can do if you can't find the exact size you need is you could remake the entire base via 3D printing in a size that is compatible with an obtainable cover. In this case, one of us 3D modelers could make that base for you in just a matter of minutes, which could then be 3D printed in brass.

Good luck with it.

Well that begs the question of what does Shapeways have that is an acrylic material? Acrylic is the only thing that will stand up to UV exposure.

And I am sure that whatever you might be able to print, will have to be polished and that it will still probably have some layer lines in it. If it can be printed in a suitable material that is the least cost and time. If I have to machine it out of a piece of acrylic that will take a lot of time.

Thanks for your comments.

Bob Price
518.895.8954

Hi Bob,

Shapeways Frosted Detail Plastic is composed of acrylic, however I don't think it will stand up to the sun's ultraviolet light because it has no UV inhibitors added. I know that has no UV inhibitors compounded into it because they use ultraviolet light to polymerize the material during the printing process. I've never tried it but I'm thinking that the sun would do damage within a few months without these UV inhibitors protecting the plastic.

On the other hand, after typing that I just realized that you can probably obtain a clear coating that has UV inhibitors built-in. That might be something to look into because you're right, 3D printing will most definitely be the easiest and possibly cheapest route. As for print lines, if you use Shapeways' Frosted Extreme Detail plastic the print lines won't be much of an issue to remove as they will be barely visible because the layers for Frosted Extreme Detail plastic are only 16 µm thick, which is barely visible to the unaided eye. One thing to keep in mind though about Shapeways' frosted Plastic is that it is on the fragile side. Like for example if you were polishing it up at your workbench and it slipped out of your hand it's going to most likely crack when it hits the floor if your floor was a hard surface. It wouldn't shatter, not like glass, but if one of the edges were the first to make contact it would have a high probability of cracking a chunk off that edge.

I use a high quality varnish on my boat that has lots of UV inhibitors in it. So maybe that would provide the protection needed. But that begs the question of what is used to make automotive headlight housings. Those are, I think, massive acrylic castings in some of the most organic shapes possible to fit with the wild designs being used on cars today.

So how much to make two or three of these little buggers?

Thanks

Bob