Technical Casting Traditional Parts from Rapid Prototype Parts?

I looked around here and online, but can't seem to find some first hand, experienced feedback.

Has anyone here used a rapid prototyped (3D printed) plastic part for casting patterns? Obviously the traditional way would have been to construct from wood or another material. Any reason a plastic "grown" part couldn't be used with the usual surface treatments as any other acceptable material?

I would like to hear from anyone that has done this or has experience casting. I would be interested in what media you chose to use (PLA, SLA, whatever) and any other details.

Thanks for any help guys!
S

 

Scooter,
We made some casting plugs when I was in school, not all for car parts but some where. You have to remember to allow for your setback when you are creating your 3D model.

 

The OP shows using some printed parts in this thread.... http://www.jalopyjournal.com/forum/threads/reproducing-an-emblem-tech-week.993104/#post-11189385

 

I failed to mention if you are investment casting and not sand casting you won't need to create a setback in the plug.

 

Yeppers! Would be for sand casted, not investment.

 

Great! Thank you! I'll look at that...

 

@loudpedal is your guy. I swear I heard him talking about 3D printers on FB or the Utah group, a while back.

 

Thanks buddy! If he doesn't chime in, I'll shoot him a PM...

 

Hi Scooter

You did not say what type of castings you are going to make, since the 3D build is going to have the layered lines from the build and they take some doing to get them covered up for a smooth pattern

For a 3D print they have two different build rates regular & fine [ .003 -.005 vrs .0006 for the fine ] and the fine is a lot smoother but more pricy since it takes longer to print

That build plastic is tough stuff and is hard to sand, then you can loose your detail when priming & sanding

Its all a trade off of what you are going to cast and what you want to spend, these 3d people don't say too much about all the finish work that needs to be done for a smooth part

Good Luck, Don

 

Three places that might help are on youtube

Doubleboost channel - He has some great casting and machining videos.

Keith Rucker he also does some great casting videos and has used 3D printed patterns.

Myfordboy some great casting tutorials.

 

Doing the finish sanding has still got to be way quicker than building the pattern from scratch. If you've got more money than time.

I think the ability to 3d scan and then print a new part upsized to account for shrinkage will revolutionize the short run repro industry.

 

I just the videos from the Tech thread linked above. Holy crap! Learned a ton! Slightly different process, since it's investment casting. But similar, overall, I guess.

Great info, guys!

I will be doing sand casting, in my case. Depending on how well the part(s) do, it may turn into more than that.

I design and print parts for RP on a regular basis, so I'm pretty familiar with the materials, and you're right, there are some side effects to not printing in a decent resolution. Clean up will be the key, or maybe simply coating the RP part so that I'm sanding down to the RP part instead of trying to sand the RP part itself. I frequently have to sand this junk (usually a Polycarbonate) and it SUCKS to sand.

GREAT info! More learning to do!! Thank you!

Fully agree!!! With desktop RP machines reaching home-use status, home-brew parts are going to go crazy! I love it! Exciting times!

 

We were on the very front end if 3D printing when I was still in school. Early enough that each piece had to be hardened after the fact to keep the intact enough to use for a plug. What we did was harden them then work them with a dremmel then harden them again.

 

So maybe, in addition to the slight up-sizing for shrinkage, maybe taking into consideration some kind of coating for the RP parts should be considered after printing. Sort of like a sandable high build 2K primer, or something similar that doesn't need a top coat that can just be cleaned up and sanded down to the base surface of the RP part, so that any lines/grain from the print is filled in and a nice smooth surface can be achieved.

 

WOW! That's some work!!!

 

LOL I still got a to scale plug on my desk. The part was too big for the printer but I just had to have it so I scaled it and kept it for a souvenir. I still got the file somewhere so in the event that I get to a 3D printer again someday I can make my plug ad be in the vintage parts business. LOL

 

I've done it. I'll be back later.

 

Practical Machinist has a forum on 3D printing that's fairly active. Might be worth checking there to see if there's any info you can use.

http://www.practicalmachinist.com/vb/additive-manufacturing-3d-printing-new/

Is there someone around the Charlotte area that does sand casting? Or would you have the work done elsewhere?

 

I don't think a hammer and chisel carving a slab of stone qualifies as "3D printing".

 

Well you know smack your finger 3 times and its 3 ds.

 

z-corp has a material called z-cast you can cast direct to.

 

I've always wondered about using this for patterns. Does the software allow for scaling adjustments? For shrinkage that is.

 

My goal was to build replica frames for twin cylinder 1911 Excelsior Autocycles. The original frames were constructed of lengths of straight tubing brazed into castings.
I had the castings on an original frame digitally measured, had 3D models produced in syrene from the measurements and had molds made of the models and then cast in 4140 Some molds had to be modified to compensate for shrinking, distortion etc.
As Alchemy said earlier some smart person should develop 3D printer softwear that produces models with compensation for shrink etc.

 

My question is why not skip the casting process and just have the part made out of metal with the 3D printer? They can laser sinter many kinds of metals now. Unless of coarse you need more than just one part, then casting makes sense.

https://www.stratasysdirect.com/technologies/direct-metal-laser-sintering/

 

Strength.^

 

Scooter; Try this; http://www.alloyavenue.com/vb/forum.php

Feel free to join in. Some of the guys on that forum are profession foundrymen, and all of us at least dabble in backyard foundry work. A fair-sized handful actually do cast iron, in thier backyard, with waste-oil fueled furnaces.
And yes, there are a few that use lost PLA, (I think) for pattern making.

Roger

 

I've had a large 3D printer(16x16x9 build area) for almost a year now. It sure can be used to make casting patterns, I intend to with mine. The best way to finish the surface is to either expose it to an acetone vapor bath, similar to how tv shows use crazy glue to fume and adhere to fingerprints. Or use regular bondo to fill in between the layers and sand it to as fine of a finish as you want to. As long as you don't make the shell of the pattern too thin, it can easily withstand repeated compressing in the core boxes. You'll just need some form of modeling software to create your model to be able to print it. I use Solidworks.

 

I was going to make my way over there. I haven't logged in over there in a couple years. I'll check it out. And not much for casting in the Charlotte area, at least not that I've got good feedback on. There is a place just over the boarder in South Carolina that is doing some parts for a guy I know. Can't remember the place, but so far I'm impressed and was going to try them out. They don't have limits on quantities.

Most 3D Modeling software has the ability to do a simple scale. So calculate the percentage of shrinkage for the type of material to be cast in and scale the part in CAD accordingly.

Pretty familiar with "metal printing". It's REALLY far from being cost effective. It's really great for certain specialty applications, but we're not quite there yet on technology to make it cheap enough to replace casting. It's AMAZING stuff, though!

I'll check that out! Thank you!

I was just thinking about you the other day when I was looking at my 6-71. Did you ever get those injection bodies together? I need to get up to speed on your stuff. I've been away for awhile. In fact, I had thought about talking with you about making some of my parts if the guy I'm thinking of using doesn't work out. Maybe we can talk about that offline.

So yeah, maybe a skim coat of lightweight filler or high-fill primer, smooth it out, shoot it with a lightweight paint for longevity.

 

GREAT! Thank you for sharing that!

The printers basically just print whatever you tell them to print, so really it's just all handled in the software. Easy cheesy. I've never checked out to see if SolidWorks or CATiA have a built in scale feature directly linked to material type, but that would probably be a nice feature to take the calculation errors out of the process.

 

We had a SSL (selective sintered laser) vendor in at work earlier this year. We gave him a complex part to make that is currently made in multiple parts. So he makes it in 1 piece. The rub was that the finish was not even close to a good machined finish, maybe a 250 um overall.

Plastic parts, we make all the time for concepts and mockups. Again, the surface finishes are just not there. There is some set up within the STL file that will improve it, but to a point.