[V8Goose]

Hi...

Dumb question: I don't understand how to mill an object that needs milling on both sides (top and bottom). For example, a cube with a hole bored from each side that needs to meet perfectly in the middle. How do I ensure a perfect zero when I flip the object over?

Thanks

[keebler303]

A cube with a hole is a basic example, you could just use a standard vise and a vise stop to locate the work in the vise jaws. More complicated work may involve soft jaws, fixtures with dowel pins or machined bosses, etc.

Matt

[V8Goose]

Thanks for your quick reply.

Ok, that makes sense. How about for something more complex... lets say an aircraft propeller. The centre hole and hub is the only common feature on both sides as the blades are convex on the top and concave on the bottom as well as the profile shape as seen from above.

In this example, after carving one side, drilling the hub and the profile I flip the blank over. What methods are used to tell the mill head where a) the face of the blank is and b) a common reference point so both sides of the propeller are aligned?

Thanks again

[keebler303]

Use a pin for the center bore. A dowel in MDF would probably be sufficient. You would want to leave small "tabs" along the propeller which would keep it attached to the blank. Then you flip the whole block over and do the other side, still leaving small tabs to hold it. Once the cutting is finished, you can use an exacto knife or small coping saw to cut the "tabs" and then use some sandpaper or a file to clean up the profile.

Matt

[osphoto]

Two sided propeller...

Same as the example given. Just leave enough material behind so that you can make references from.

Don't remove the propeller from you stock until side 2 is completed. You can use bridges in the material to help with keeping your propeller safe in the stock. Leave enough bridge work to keep your part firm while cutting 2nd side.

Large squared pieced of stock. Center cut your propeller. The center hole is your first reference. Cut a 2nd hole, offset from propeller and this can be your 2nd reference for when you flip the part over. Cut anywhere from 1/2 deep to full but remember to leave stock for side two.

Mount side two and proceed with side 2 of cutting.

[V8Goose]

Thank you both.