3-D printing inquiry for 1935 Chrysler Airflow part

[Gary_Ash]

The grille for the parking lights on 1935 Chrysler Airflow cars seems to be a one-year-only part.  Airflow production was under 8,000 cars that year, according to Wikipedia.  How many survivors?  How many people want and will pay for a replacement grille?  I don't think this is a "get rich quick" opportunity for anyone.  As it stands, except for Pete (the OP), no one else has jumped in to say, "I really want one or two of those!"  Maybe Pete can find some buyers. 

 

One advantage of 3D printing is that when you want one more copy, you just load the file and the plastic filament and hit the print button, no labor real involved.  Yes, the print time will be about 26.5 hours on my printer, but I'm sipping my evening Luksusowa vodka martini as the printer continues to run without any effort from me, should be done by lunch time tomorrow.  And, Pete has lots of work to do on the car before he needs the parking light grille.

 

While the foundry I have used is only about 30 miles away, I haven't visited there for the last few jobs he has done for me.  I mail the patterns, he mails back the castings.  Maybe I should go visit for this project as face time is always important for maintaining relationships.  Besides, it's fun to see how they actually do the work. 

[edinmass]

3D printing is a fun topic and when we give tours of our museum, the shop tour portion almost always has someone asking or commenting that you can make any part you need fast and easy with 3D printing. When Gary did my project.......we made some extra plastic and rough cast pieces. They are on display on my workbench on the large surface plate for show and tell. Also, a water pump shaft and Helical gear Joe P made. It’s always an interesting conversation when I explain shrinkage, machine work, and modifying the design to make parts better or easier to deal with. The 3D printed metal parts always impress the folks.......when they actually grasp the part and feel it’s strength you can see they are thinking Star Trek duplicating machines. There is no free lunch making parts from 3D printing, lost wax casting, or machining from billet. In the end, it takes lots of time from experienced people with very special skills..........which are all valuable attributes that deserve fair compensation. In the end, very seldom do the numbers work out that you can make and sell parts and actually cover just your costs.......we won’t even discuss making a profit. I’m thankful for Gary and the time and effort he made in helping me with my projects.............and the same goes for Joe P. The two gentlemen assisted me with no expectations of profit or reward......they helped because they are fellow hobbyists who found the work interesting and rewarding. Thanks gentlemen, you made my cars much better vehicles that I can use and enjoy, and I am forever in your debt. 

[Terry Harper]

Many ways to do things - Lost PLA, Silicone molds & lost wax, 3D printed and plated, etc.  - the fact we have so many options is pretty amazing. Recently I had to get a quote for some castings. Unfortunately the size of the parts made 3D printing the patterns a no-go. Likewise spending over $17,000.00 to hire out the patterns and core box work was out of the question as well. Since we didn't have access to original parts (other than for reverse engineering) we couldn't  use those as patterns either.

 

The solution was 3D printed molds. Having modeled the parts in Solidworks as well as creating the shop drawings, It was simple to send the foundry the STL files and to discuss the various details of the project.

 

granted the 3D printed molds are a one shot deal but since I doubt very, very much anyone other than this particular client needs a set of these castings that is fine with us. The cost savings over traditional patterns has made the project affordable.  Not that long ago this option didn't exist. 

 

Is this whole process cheap? Nope! As an example: Part No. 54 (Steering Quadrant) - the 3D printed mold was quoted at $4,458.00, each casting at $345.00 ea. (the price per casting drops with quantity) Mind you, this doesn't include  my time spent on the reverse engineering, developing the 3D model, shop drawing and calculating tolerances etc.  for this one part which would have been about 6-8 hours. 

 

To keep the cost in perspective that steering quadrant weighs a little over 73 lbs. so it's not a small part. Here is a rendering and couple of clips from the shop drawings.

 

 

 

 

 

 

Edited January 19, 2022 by Terry Harper (see edit history)

[Paul Dobbin]

This has been a amazing thread.   I sure hope Pete Phillips has been watching.  Has anyone heard from hiim?

[1939_Buick]

54 minutes ago, Paul Dobbin said:

This has been a amazing thread.   I sure hope Pete Phillips has been watching.  Has anyone heard from him?

Pete posted on the forum about 5 hours ago.  He may be working (or sleeping)

[jdome]

 

These are some complex parts I cast in steel with lost wax. The above mold was made using an original 1911 exhaust cut out. Shrinkage was not critical in this case and some shrinkage was minimized because of the open cores. The green parts are wax and ready to send to foundry. The steel parts are new castings that has been machined. There were a total of 7 castings I made for just one cutout. The 3 inch diameter round part is the popit valve for complete exhaust outlet but it has a skirt that turns to open a side outlet tapped for 1' pipe to the whistle. Notice the yoke stand off for the rocker arm to activate the popit valve. I think the main body would be tuff to make by 3-D printer.  Coring saves a lot of machine work but I left enough meat to require honing out so exhaust pipes would fit and so the valve & seat could be machined to close properly.

 

Aside from this being relatively inexpensive, I'm a hands on hobbyist that likes to do as much of my own work as I can. I'm not looking for any business, I can't find enough time to work on my own cars. I still have a real job that gets in the way of my hobby. I just want to show what can be done with lost wax.  There is about $40 in silicone in the mold,  couple bucks worth of wax and the casting was under $100. the box was made of scrap wood and some brass & aluminum tubing I had left over from other projects. I'm not a machinist so I had to farm that out to a commercial shop and that was about $500.  Most of that cost was to make fixtures which the shop gave me so That is where the cost savings would be if I made multiples.  I have lots of hours making & re-making the mold to get it right. Now that I have the mold, It would take about 15 minutes to heat enough wax in an open pan on a hot plate and about 10 minutes to pour the wax in 2 stages. About 60 minutes to cool and extract from the mold and its ready to send to the foundry, OR make another.  I have a pressure pot that melts wax in a pot hooked to regulated air pressure to pump hot wax into some molds but this one worked out better by pouring wax in 2 steps. 

 

The green wax Y in the photos is actually another cut out part I made for another car from original parts. It is also cored out using  silicon for the core.

 

The foundry I used attaches my wax pieces to a "tree." The tree is a wax pipe they attach parts to with wax sprus. They dip the tree full of multiple parts in a vat of ceramic slurry and let it dry. They dip it several times to build up a shell. Once it dries they bake the ceramic and melt out the wax and then pour alloy in the shell while the ceramic is still hot. Its a great way to cast cored parts because the slurry coats the inside of the wax piece, as long as there is a hole big enough for the slurry to flow in and excess to drip out. It can't puddle inside or it won't dry/cure properly. 

 

 

[Terry Harper]

5 hours ago, jdome said:

I just want to show what can be done with lost wax. 

Fantastic work and thank you for sharing! I have always wanted to try lost was castings. In fact I have a couple of silicone molds sitting on the shelf and some materials stored away from another project. Just need to make it happen!

[Gary_Ash]

8 hours ago, jdome said:

These are some complex parts I cast in steel with lost wax.

Please tell us the name of the foundry that will investment cast steel parts in small quantities.  What type of steel did the foundry use?

 

I once got a tour through a factory that produced titanium golf club heads by vacuum investment casting.  The production rate would make your head spin and the surface finishes were fantastic.  They had really big bucks invested in the equipment.

[jdome]

The foundry that I use for this type casting is Harbor Casting in Cuyahoga Falls, Ohio (near Akron).  If I remember correctly, they have another foundry in Jackson MI. and another somewhere down south in the Atlanta area I think.  They cast aluminum brass & Bronzes and certain steel alloys like 4140. 

 

 

[Gary_Ash]

After 26 hours of printing, I finally got a good part to use for testing the fit.  The addition of the small tab to end of the beak helped to keep things together and the beak looks good.  This one got printed in black PLA because I used up the silver material.  I'll send it to Pete.  If it fits OK, I'll print copies at 2% oversize for casting in silicon bronze.  They will then need polishing and plating.

 

Now, how many of the remaining 1935 Airflows need a new parking light grille?  Given how thin the original pot metal was at a number of places, I'll bet there are more than a few cracked grilles.  

 

[Terry Harper]

Very nice Gary! 

[1939_Buick]

Looks very good.

Did you use that formula in the CAD file or all by measurement then into CAD?

 

Advertise in the Airflow club, you may get some customers. (and requests for other complex parts?)

https://www.airflowclub.com/

[Larry Schramm]

Gary,

Great looking work.

[Gary_Ash]

On 1/19/2022 at 5:23 PM, 1939_Buick said:

Did you use that formula in the CAD file or all by measurement then into CAD?

I assume you were referring to the formula for the tri-axial ellipsoid, x²/a² + y²/b² + z²/c² =1, where a, b, and c are the lengths of the semi-axes in the three directions.  I did finally figure out how to get the CAD program to draw the ellipsoid, but then I discovered that the actual shape was a blend of two shapes.  I wound up lofting the surface from some curves, sort of the way ship hulls are designed.  I figure this kind of stuff keeps my brain active in a better way than playing video games.  Fortunately, I can still get my brain to drag out memories of plane and solid geometry and descriptive geometry (see Wikipedia) that I took in high school 60 years ago.  If only I could remember what I had for lunch today and where I put the car keys...

 

Pete, the guy doing the restoration work, has good links to people in the Airflow club.

[Walt G]

Totally amazing

[bryankazmer]

There are a series of Youtube videos by a company called Netzsch that go through how the different types of additive manufacturing work.  Really good content but some familiarity with chemistry and physics is assumed.  Covers plastic, metal, powder, liquid, line feed.