help with "engine turned finish" please

To All,
I have been asked to quote a job making 4 dashboards out of 3/16" 304
stainless steel sheet. The customer wants an overlapping "engine
turned" or "fish scale" look. The two preceeding terms are what I have
heard several people call this look. Anyway, I have posted pictures
and text to the dropbox. The files are: dash.txt, dash1.jpg, and
dash2.jpg. The diameter of each "scale" is 1 inch and the overlap is
1/2 inch. Since several need to be done and since they all need to
look the same I need a method that repeats well. These parts will be
done on a CNC mill so spacing and tool pressure will be the same for
each mark. In the past when I have done this it was just for myself
and so time wasn't really a factor. I have used sandpaper discs, wire
brushes, and abrasive loaded wooden and aluminum dowells. But these
methods don't seem to me to be the best when doing over 2000 marks.
Furthermore, since the sheet is hot rolled and pickled it looks like
it'll have to be either ground or run through a Timesaver to remove
the hot rolled surface and leave a finish smooth enough to put the
swirls in. So, anybody here done a lot of this? Or is there a supplier
who makes sheet like this?
Thanks,
Eric R Snow,
E T Precision Machine
Reply to
Eric R Snow
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Eric,
Use a Cratex rubber abrasive stick in a spring loaded gizmo. I did this once years ago works real good. I had to design and build the spring loaded holder, but if I recall, it wasn't very complex.
Regards
Mark
Reply to
MM
Thanks Mark, I have used Cratex in the past but didn't know that it came in 1 inch diameter. I'll look in the catalog Eric
Reply to
Eric R Snow
They sell high-end kitchen countertops with this pattern. The ones I have seen have swirls about 4" in dia. I'm pretty sure they make it themselves. I would contact a countertop fabricator who advertises stainless steel and they would probably tell you how they do it or where to get the stuff.
Reply to
woodworker88
Very nice, Eric, but I think I would have opted for a 2" pattern. These look a little too busy. JR Dweller in the cellar
Eric R Snow wrote:
Reply to
JR North
I use the Cratex sticks as well. FWIW, in order to get a nice finish, I find it helps to polish the metal before using the Cratex. The Cratex may not abrade all of the metal underneath it, and it helps if the finish that "escapes" the abrasive is shiny.
Peter
Reply to
Peter Grey
Eric; I agree with Peter about the need to use a polished surface before doing the "engine turning". I make my own tools for this operation. I purchase a stack of large flat ink erasers and drill them with diamond core drills to make the required size of abrasive rubber tool. I mount this with super glue into a recessed machined holder and use it on the vert milling machine. The diamond core drills allow cheaply getting the required sizes for the jobs I do. Will this help? Jim
Reply to
JAMES RISER
I made a custom air cleaner for my boss's race Firebird. He had a huge K&M filter, and wasn't pleased with the position of the commercial housings -- they interfered with his scoop. So, we dove into the shop.
After all machining, we engine-turned the top on my old Cincinatti #2 using 1-1/2" Rol-lok disks. The finest grade gave the most pleasing finish on 6061. You might need a stouter cut for steel.
LLoyd
Reply to
Lloyd E. Sponenburgh
Greetings Jim, It seems that using rubberized abrasives is the way to go. I know that the SS is going to be needing polishing or grinding first. Since I need to do so many spots I'm going to make a spring loaded holder for the abrasive. I'm also going to try using coolant to see if it speeds things up. BTW, with your CD and a DVD from another guy I was able to get a nice spun piece the first try. Eric
Reply to
Eric R Snow
Eric,
They do make a 1". It's #166
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The grits are color coded. I think the green is what I used. My parts were 14ga 316SST
Mark
Reply to
MM
Thank you. I'll order some today. Eric
Reply to
Eric R Snow

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