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Metal scrapping, flaking & engine turning
The question was asked by Bill Funk if they originally scraped the engines on Bugatti's and the answer is yes. The apprentices were given the job of scraping, flaking and engine turning the firewalls. Some were well done and some were poorly done. It was all done with by hand and was a tedious and labor intensive job. This is the original pattern which was on this particular car which we found by taking a sharpening stone and water and just skimming the top surface. The pattern is made in squares with the shape of commas which you can see from a close up photo. The castings on the Bugatti's I have worked on were very porous, unlike British castings, and I'm guessing by putting on decorative scrapings it helped hide all of the flaws. When polishing the covers there were 1/8" craters with dirt and slag in them which had to be cut out with a dremel tool. I then used a ball dremel tip and undercut the hole so i could put in a soft rivet and mashed it in the hole. After filing and sanding I polished the piece and you could barely notice the spots and after the scraping was done they were not noticeable. Other parts of the engine were repaired in this manner.
Flaking is done with a straight scraping pattern done randomly. The engine in the photo is of a 1931 T46 which has flaking on the block and engine turning on the water and oil jackets and the firewall. I am replacing the water jackets which are cast and need to be finished to match the lower oil pan jackets with engine turning. The other photos are of two power scrapers I have which have the straight pattern and half moon pattern. The shape and size of the patterns are determined by the speed of the machine and the speed you move the machine as shown by the sample piece. The last decorative pattern is done on the firewalls. The turnings are in alternating rows which zig zag and really don't look to good. The firewall shown is from the T57 and has the chassis number 57314 stamped on it.
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James Hery Last edited by jhery; 10-18-2018 at 09:51 AM. |
#72
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surface finish
Thanks for the explanation. I figured there was a lot of practice put into that. One trick I have found with engine turning is to use a guide to keep the rows straight but do the spacing by eye. Seems to look better than a perfect pattern done by CNC.
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Bill Funk |
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