I’m in need of recreating a replica of a no-longer-manufactured wheel for a classic race car. In the picture below, the part in question is the gold central disk, or “wheel center.” The one I need to create is very similar, about 14” in diameter with a z depth of 4”.
Is the Shapeoko 4 capable of milling aluminum on this scale? I’ve seen plenty of aluminum bits and bobs, but nothing of this scale.
On the reverse side, the spokes are pocketed for weight savings. Is two sides milling feasible for a total amateur?
And finally, since I’m looking to create an exact replica of a 60 year old part that hasn’t been manufactured in the same time - is there an easy way to fast track the modeling of something like this? My modeling experience is laying out squares and rectangles for woodworking projects in SketchUp, so some magical 3D scanning would be the bee’s knees!
I don’t want to discourage you but this is quite the undertaking for a beginner. Is the machine capable of cutting something like this? Most likely. The Z depth of 4 inches will be a challenge depending on the exact geometry of the part. I bet it could be done though.
Your first step would be to model it which is also a big hurdle for a beginner. There is no magic bullet for modeling it accurately unfortunately. 3D scanners exist that could probably produce a point cloud accurate enough to turn into a model but they are incredibly expensive and you still need to create a model from all the points. This could be modeled just by taking a bunch of measurements and spending the time to create it from scratch.
After you have modeled it, you would then need to plan out all the toolpaths and some sort of fixture to hold it for the back side machining.
It would be a great learning experience. I really am not trying to discourage you from doing this. It is just a very big step from squares and rectangles in wood. I would suggest starting with something smaller in aluminum in order to learn the skills in both CAD and CAM that will enable you to do this without pulling your hair out in frustration.
Would this part be intended to be functional or just a replica for show?
That said, if this is to be an actual part, you need to source a piece of aluminum which is suited to this, in terms of stress-relieving, zero casting defects, &c., and the cutting has to be smooth/even/consistent enough not to create areas which differ significantly from other areas which should be equivalent so as to evenly distribute stresses — do you know of a company which can inspect the part after manufacture to verify that it will be suitably safe?
Your range of motion is really close to 4" on that machine, right. You can move the spindle to accommodate taller parts as long as your clearance to the gantry & axis mounts is sufficient.
I’d be really wary of the repeatability & accuracy of a V-wheel & belt driven machine. You’re going to have to really baby it as far as forces of the cutting. Very shallow & light cuts. I’d guess it’s going to be a 20 hr or more job.
You’re also going to want to ultra-calibrate your machine. Flat, square & accuracy of axis movement.
As for modeling, that could be a challenge if you’re not experienced with it, and you would definitely need software a bit more advanced than Carbide Create to get an “exact replica”** of your part.
** What do mean by “exact”?? i.e. what are your tolerances?
If you can measure the part accurately enough, I can model it for you.
Which brings us to machining. What software will you use to program the toolpaths? And more importantly, what formats of 3D data will it accept?
You can buy stress relieved material. Any additional stress from machining can be accommodated by your machining strategy. remove most of the material from both sides and balance the stock before finishing.
A 14" x 4" thick chunk of 6061 T651 tempered & stress-relieved aluminum is going to run you ~$350
Carbide ZrN coated high rake tools for cutting aluminum $30-$60 a piece.
Sounds like a lot of “Cons” vs “Pros”, but it certainly can be done. Depends on your commitment & investment.
It could be done but it is going to be very expensive and you better have your work holding, tool paths, and feeds on point because a 15" x 4" thick block of aluminum is a few hundred bucks.
The modeling will be the easier part of the 2 fairly difficult tasks but this is far from a simple project.
Start with glued together sheets of MDF and scale it down to 5 x 5 inches and work it out before going full send.
