Station buck thoughts
 

So it came time to start the CAD part of the buck making project. To make sure I wasn't giving confusing or ambiguous direction to Dan (the guy doing the CAD work), I decided to write down my thoughts/needs. I've found the process of putting words on paper (so to speak) forces me to think things through and verbalize what's going on in my head. Here's what I came up with:

Modern-day Miura Station Buck

Objectives
1. A tool that can be used to provide reliable and repeatable surface information for the Miura body. By surface information I mean body skin shape, placement and measurements from “known” reference points like ground, axle centerlines, windshield, etc. Contour gauges can be lofted from buck stations for purpose of designing and fabricating inner body structures.
2. A tool for verification of body panel shape and form. Body panels can be placed against buck during shaping to verify their fit via visual observation from backside. Buck stations will need “windows” cut in them for visual access.
3. I have constrained workspace in my garage. For short periods of time, I can free up enough space for a full sized station buck but not for the duration of body making phase. I’d like the buck to have adaptable modules such that a module can be used separate from other modules but when the buck modules are joined they should do so with reliable indexing.
4. For purposes of symmetry and accuracy, I’d like to hammer form selected body openings on the buck. Examples include front and rear grill openings, headlight openings, and hood vent openings. Perhaps wheel openings but not sure on that one yet. In general, metal shaping will be done off buck and buck is for shape verification. In these selected areas, hammer form modules should be attachable to buck for shaping and flanging these openings. All body panels to be hammer formed will be made from Al 3003, .063 thickness.
5. I work mostly alone and will at times need to move or re-position the buck and/or buck modules. As such, I’d like to keep buck weight manageable by not over engineering it with over sized structural components.
6. One time use. I am a hobbyist and my intent is to make a single Miura. If a second use is needed, a second buck can be cut from CNC files.

Specifications
1. Buck station thickness: ½ inch
2. Transverse buck station placement should be every 8 inches in general. Placement can be closer in places of rapid body shape change or near edge of buck modules and hammer form modules.
3. Buck design should include 5 modules: front clip, rear clip, middle section, drivers side rocker, and passenger side rocker.
4. Longitudinal and transverse station design in the module interface areas must include a means of reliably indexing the buck modules to one another. A design that requires some buck module disassembly and reassembly to join and index modules together is OK. I can foresee use cases where front plus middle modules minus rear module will be needed and likewise middle plus rear modules minus front.

Ideas
1. Special longitudinal members/stations whose only purpose is to accurately index the buck modules to one another. Given the length of the car (i.e. > 8 ft.), the full length longitudinal stations need to be cut from multiple sheets and joined/indexed together anyway.

Here's a graphic showing buck modules in different colors:

http://www.allmetalshaping.com/pictu...ictureid=19193

Station buck progress
 

Here's some progress pics of the Miura buck as it's being designed in CAD:

http://www.allmetalshaping.com/pictu...ictureid=19195

http://www.allmetalshaping.com/pictu...ictureid=19196

http://www.allmetalshaping.com/pictu...ictureid=19197

http://www.allmetalshaping.com/pictu...ictureid=19198

Station buck progress
 

Progress pic for 3D modeling of station buck.

http://www.allmetalshaping.com/pictu...ictureid=19229

mdf or plywood can be cut out with a cnc router. many hobbyists have them (including me) and that would be a lot cheaper than a water jet or laser. Accuracy is more than good enough for a buck.

Joel, if you're going to use MDF use 3/4" minimum. The size of the panels you'll need are too large for 1/2". Anywhere you're going to screw parts together, insert and glue wood dowels. MDF does not like wood screws.

In the fist first picture below, notice that each station has a printout bonded to it that has the profile of numerous stations printed on it. Meaning that only one or two sheets had to be designed to include station profiles for the whole car. Notice also that you don't see the printouts glued to the right side of the stations. They are probably on the back side to give an exact mirror image. You could also have your inner structures printed on the same sheets, maybe in red or a different color than the outer profiles. Then cut when needed.

The second picture is the Caddy buck I made recently. The edge that the sheet metal will touch. I cut a 45 degree bevel on each side which left only about 1/4" of material that will contact the sheet metal. No need to fair with grinders and sanders.

The last picture is the spine of the same fender buck . Notice that I had to bolt a piece of 1 1/2" angle iron on to stabilize it. The spine is about 7 feet long and just in a couple days of setting on the stand, it started to sag. MDF is pretty stable but it will warp if large spans aren't reinforced.
In long smooth areas I use about 12 to 16 inch spacing. Less in areas with more complex shapes. I was looking at the CGI of your buck design and it appears to have far too many stations. You will be able to see or feel highs and lows between much larger spacings so I think some of the stations on your last drawing aren't needed.
As for using the buck on the ground and on the chassis, if you locate your "windows" carefully to outline the obstructions on the chassis, you might be able to trim the buck quick and easy when you're ready to set it on the chassis by simply cutting a few window frames out. Lifting it without breaking it will probably be one of the major challenges in this operation. Good luck, I'll be watching your progress.

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Very useful post Jack!

For those that don't like large amounts of wood dust – who does? – when the weather allows, do it outside.

I sometimes weld and oxy-cut outside when the season is right, to reduce the inside fire-risk,

Cheers Charlie

Thanks for the suggestion Scott. I'm investigating the CNC router option now.

Jack: I've decided to use 1/2" plywood for station buck. I didn't like the extra weight of MDF and going with 3/4" would just make it even heavier. With plywood, I can also use wood screws.

Thanks for all the helpful info in your post!!

Here are the final 3D designs for the Miura station buck:

http://www.allmetalshaping.com/pictu...ictureid=19250

http://www.allmetalshaping.com/pictu...ictureid=19251

http://www.allmetalshaping.com/pictu...ictureid=19252

http://www.allmetalshaping.com/pictu...ictureid=19253

All the stations lay out on 13, 4' by 8' plywood sheets. Here's an example:

http://www.allmetalshaping.com/pictu...ictureid=19254

I'm now investigating the best, cost effective method to have these CNC cut. Once cut, the pieces are suppose to slide together where they are notched. This sounds great in theory, we'll see how well this works in practice.

For some of the body openings, I'm planning to have buck mounted hammer forms for turning the flanges. For example, grill, headlight, and hood vent openings. I'm hoping to have these hammer forms shaped on a CNC router from blocks of glued together MDF. We'll see how practical this is.

More updates to come as I figure this puzzle out :)

Joel,

I just found this thread after somebody mentioned it in your C5GTO thread. How do you have the time for all these awesome projects? :)

I have a 5' x 8' capacity CNC router and would be willing to help you in any way possible if needed. I realize Cleveland Ohio is quite a ways from CA but just wanted to make the offer.