A couple acquaintances of mine on the West Coast run Inline Carbs on their show cars. One is a 41 Willys coupe with a blown 468 CI Big Block Chevy. The scoop is a Blower Drive Service (BDS) 2 x 4. Those are set up to house two circular air filters in each opening. The owner liked the look of the open scoop without the filters and had made an adapter that also housed a flat filter element. It worked well but he asked if I could make a more streamlined adapter from the carb to the scoop, and he was willing to go back to the in-scoop filter elements. So I got to programming, fired up the CNC Router and came up with this. I’ll cast the pair together as the back-to-back arrangement not only gets me both in the same pour, it also makes the patterns more rigid and helps keep them flat during molding. Best, Kelly
That looks so much better, Kelly! It is in keeping with the general lines of the car. Very fine creative design and execution. I have a feeling there will be a few more trophies on the shelf soon. It occurred to me the other day that we had not heard much from you. Now I know why. Denis
Thanks MS. Very nice of you to say so and much appreciated. The owner of the Willys liked it too.....of course there is that little detail left of turning the foam into metal . I've been busy finishing up projects and although the projects had castings, the completion work did not. This was actually a short little project I slipped in for a repeat customer.....and a worthy cause. Best, Kelly
Those are some really nice lofts, design-wise. What kind of stepover did you use on your surfacing tool path. Very smooth! Time to "toil and fettle??"
The program only uses two bits and is about 25 minutes per side. (well three with the round over operation but that's only 30 seconds). They are both carbide double flute spiral bits, .25D x 2" cutting length. One is ball nose. I bought one of each that was supposedly rake and relief for foam cutting but I cant really tell any difference in performance between those and ones spec'd for wood working. I experimented a little with scanline 3D mops but be it horizontal or vertical, neither was ideal at the interface with the circular boundaries so I thought they were all better suited for waterline method. I did use a roughing cut first then the finish had .015" depth increment with .2 stepover and resolution. 90-120 in/min. Sort of interesting that those surface finishes were better than the flat bottom end mill cuts. I dipped them yesterday. Maybe tomorrow or Monday weather dependent. It's raining today. Best, Kelly
That is interesting, I'm guessing it's the sharp corner that's responsible for the coarser cut, do they make flat bottom end mills with a very slight radius at the corners and if so, would that leave a finer finish?
I commonly see radiussed end mills for metal but not wood cutting bits, just dish cutters and ball nose. I've been tempted to buy CNC Router insert tooling and just grind the radius on the insert on a diamond wheel. I suspect the witness marks on the flat bottom cuts are due to depth of cut and inadequate chip clearing. The default stepover is .4D. If I set a shallow (say <0.015") as the final depth increment, it would probably be better. Even though the tool marks/paths are visible you can't really feel them and they literally disappear with one or two light swipes of sand paper. Since foam is so soft, I've learned there isn't much return in trying to make the CNC cut perfectly finished patterns since there will always be some degree of hand finishing for the best results. If I was machining harder materials I'd probably come to a different conclusion. Besides additional programming time (unless you can import a complete surface model), the time to generate tool paths and gcode for the 3D machining can get quite long not to mention the machine run times. 2.5D machining is so much faster I always opt for that on features where possible. I have video that has some footage and discussion about cutting and finishing this pattern. I'll post that when the project is complete. Best, Kelly
These are on my list to try but good information to know. I will need to invest in some long reach tooling here soon. Most of that seems to be made for lighter composites because no one is reaching that far in unless it's a softer material. Either called corner radius or "bullnose" endmills. I had a 2 fluter for aluminum that I used for years almost. Did everything but sharp corners. Excited for the video!
I use a lot of carbide end mills for metal cutting. They are often 1/4, 3/8, or 1/2" diameter with four flutes and dead sharp corners (cheapest and most common) when I buy them. But, I practically never run them dead sharp. I first put on magnifiers and get out a diamond file (fine grit) and give each corner a few strokes --- maybe 4 or 5 --- each being careful to use the same number and and about the same length each flute. I angle the file 45 degrees or so to the point of the corner and more or less at a proper rake angle. Sounds hard, perhaps. But it is super simple and quick. The result is a chamfered corner that is much more durable than a sharp corner and that makes a smoother cut too. I do not like the cheap red-handled long skinny diamond files ubiquitous on Amazon. They are too coarse for most work and are crudely made. The DMT files are what I like to use. The generic knock-offs are quite good too. I use them for many tasks in the shop. They are very handy and last nearly forever. Denis
Great casting weather today. Mid 50’s F in the Midwest and first day of Spring! So I got after it. Coated and ready to go. Molded As it came out of the sand Degated, media blast, and finished machined The castings They fit! It was a good day. Best, Kelly
Good day indeed! I can't imagine your acquaintance/customer will be anything but completely thrilled with your results, it looks great!
Thanks for the likes and comments guys. He received it today and had it on his Willys 2 hours later. Best, Kelly
Wow, Kelly! Another great project and fine example of what you can do with lost foam. We've had a few things happen around here to keep me out of the shop, so nothing new here, but when life quits interfering with my hobbies, I'll be back at it ;-) Thanks again for the inspiring lessons! Mike
