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Wooden Trim for Antique Automobiles

posted Jul 6, 2013, 9:04 AM by Jay Gross   [ updated Jul 6, 2013, 9:10 AM ]
Here is a completely different kind of project than the trains and metal industrial parts; it is wooden trim for 1930’s and 1940’s automobiles known as “woodies.” As you can imagine, it is difficult to find wooden car parts from 1940’s that are in serviceable condition. JG Conversions’ role in this restoration process is scanning the old parts and getting STL data files of the shape to the client.  The client produces a new wooden part using a CNC controlled router. Here is a link to the client’s blog.
trim prior to preparation for 3-D scanning Front           trim prior to preparation for 3-D scanning - back

Here are the front and back side of both halves of the original pattern part. This part is about 4 feet long.

wooden trim after to preparation for 3-D scanning          wooden trim after to preparation for 3-D scanning - back

A patched-up original is used as the object that is scanned. The patch up job does not need to look good and can even consist of clear tape with a white powder spray. I can do some touch-up and repairs digitally, but it is faster and cheaper to fix the physical object before scanning. The trim is finished in a clear finish, so no putty or patches can be used for the final part. 10 thousandths extra for the tape thickness for a wood part does not matter. The client did the more important front side with putty to save money and to preserve the correct details. Lighter color paint would scan a little better; the surface can be coated with the white talc powder too. I quickly did the back with tape. The damaged tendon sticking out from the end was re-constructed using tape since there was nothing smooth to extend with the correct cross-section. The part then (after the above pictures) got another light coat of white power spray to make the surface more uniform and cover up the tape. The scanner scans thru the clear tape to the surface of the wood at the bottom of the holes I am trying to cover up! The ping-pong balls and dots are for alignment of the individual scans.


trim in good shape            measurements after SLS scan - back side


This part, a rear quarter trim was in good shape and was actually used as a pattern to (slowly and meticulously) make other identical copies using a mechanical pantograph arm and a router before being bought by our client. Defects in the wood for this piece prevent its use as an actual trim piece on a car. I digitally extended the outer surfaces on both ends around 3 inches lengthwise and covered over the complete tendons. Since the original was smooth, I was able to duplicate the individual scans of the ends, slide them down and trim them before fusing (attaching and averaging) all the scans together. It is easy to copy something, but difficult (and expensive) to create all new surfaces. The 70 inch long part is at the limits of the 3-D CNC router and the scanner. The part was scanned using a Structured Light Scanner.




3-D CNC wood milling machine/router

The client, Jeff Yeagle, has a 3-D CNC wood milling machine/router. The CNC router, pictured above can make the wooden part using a digital STL file much the same as a 3-D printer produces a plastic or metal part, but on a much larger scale. The bed of the CNC router is 45x45x6 inches. The part above of course is foam and has a much rougher finish than the final wooden part due to less cutter path overlap. The foam part are used just to inexpensively test the fit on the car. Wood parts produced this way are useful as patterns for metal sand cast parts. The cost is lower than manually created patterns (from a traditional pattern maker) or ABS plastic 3-D printed patterns especially for larger parts. Jeff does this as a service.