Custom Header Flanges - Use a CAD Drawing to drive a CNC Laser Cutter Hi Gang: I'm working away on the blown 392 project -- and I ran into a problem. I'm running Donovan 417 heads -- which have huge D-Port exhasts and a completely different bolt pattern than stock 392. That means there are NO headers available --- not even flanges to make your own. So when the HAMBer named 'VendettaAutoFab' was pitching his laser cut 392 flanges, I contacted him and asked if he could make custom ones -- if I had a good CAD drawing. He said no problem -- which is way cool. He's going to make mine from 3/8 Stainless - based on a DXF file from my CAD system. I used Autodesk Inventor to create a parametric sketch -- so that I can tweak the port design for either of my two sets of Donovan heads. (No two are exactly alike - depending on who ordered them from Donovan 35 years ago and who has worked on the ports since.) The Inventor parametric sketch model allows me to change any of the key port dimensions (port height, major/minor ellipse radius, port width, etc.. So I tweak the model, print a hard copy and take the drawing out to the shop and compare to the physical head. It only took a couple tweaks and it is spot on. Once I'm done, then I just output a DXF file and send it to Vendetta . . . their laser cutter will work right off my profile. If any of you have specialized older heads - or want something different, it isn't that tough. If you need any suggestions ar tips - drop me a PM. Once my flanges are done, I'll post up the final drawing and the results back to this thread. Dale Here is an example of a single port model in Inventor:
Very cool. You seem to have had a productive Easter, even with doing chores for the wife this morning.
measuring tap, scoring tool, drills and hole saws work good too..... lol why do people gotta make a complication of things? geterdone.
Yes . . . could be done the manual way, but given that I need to make at least 4 of them - and out of 3/8 stainless (don't want mistakes), I opted for a CNC laser cutter. Then there is the time involved -- always seems like I have a mountain of work ahead of me and never enough time. Making the rest of the headers is probably going to make me lose my mind! Dale
I pondered that, but with the flange made of 3/8 - and the fact that there are 10 bolts per side, don't think it is much of an issue. I added the profiling for appearance reasons only. Guess I'll find out
That's how I did the header flange for my Iron Duke. Drew it in Autocad and had it cut from 3/8" cold-rolled with CNC high-definition plasma. The CAD image is in the "Tech Archive" section of the H.A.M.B.
We are looking for a design for a 1935 Ford flathead engine header flange.We have a CNC at school. Please contact me at Kennedy High School 952-681-6917
Yeah, I was thinking the same thing. The flange seems unnecessarily thin along that whole top area. Those notches will weaken the strength of those upper "tabs". Maybe you could leave the flanges square and throw a few small lightening holes in them in places where you think there's too much meat in the flange. It would be a bitch making those D ports in 3/8" stainless using simpler tools. I made some 3/8" flanges out of cold rolled steel (not stainless) and I used a mill to drill the screw holes and the four corners of the square ports, a plasma cutter to cut the ports and the outside shape, and then spent a really long time with a grinder on the outside and a die grinder on the insides of the ports. Stainless would make everything take longer. So you will definitely save a lot of time having those laser cut. I just think you're cutting away some strength unnecessarily by making those notches so deep though.
Here is the final design - I listened to some of the comments and changed the profile at the top. I now have about 5/8" around the ports at the top and bottom. Just had a set made of 3/8" mild steel -- checked them against the heads and "tweaked" the design a bit --> needed to move a couple of the ports a 1/16 or so. Donovan's manually made casting patterns are not 100% exact - but pretty dang close. Here is the new design -- I'm having stainless ones laser cut this week:
Received them back - here are the steel and the stainless versions. I mounted the stainless ones on the head - everything is exactly as I need it to be. David Vette did a great job at a more than fair price! Here yah go:
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