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@david pierce wrote:
If it was me I would reduce it to the simplest and easiest way to manufacture the part that I knew how to do. The bottom of the device shows the tapers of the lathe bed machined into it. This would rule out cold rolled steel as it warps when machined this way. Is it necessary for the unit to lock into the bed with a precision fit the same way as a tailstock that would slide along the ways? A tailstock has to have a precision fit because there is no way to adjust anything. A steady rest has adjustable jaws meaning that aspect of the part is not necessary; so a flat plate would also work. The jaws resemble milling machine clamps. Do they require the size and strength that are specified in the design or could the same functionality be accomplished with brass set screws? Drilling and taping three holes for set screws if far less expensive than machining three slotted jaws and the slots they ride in.Also, three brass set screws will be at least as, if not more precise than, the sliding jaws. Steel is more difficult to machine than aluminum so does the part require the strength of steel or will aluminum accomplish the requirements for the loads that will be put on it? In short If it was me, I would reduce the design to the minimum cost and effort that would do the job properly.
That’s one of my main problems. Never having worked in a machining environment, I am ignorant of the loads placed upon such a tool on a small lathe like the Levin – and manufacturing practices. So…It sounds as though, aluminum might work in this instance. I guess I can just jump in and if it fails – it fails. It sounds like I need to back-up and re-think the design.
1) Lose the slotted inteface and just go with a flat bearing surface.
2) Use aluminiunum
3) Employ a different holding scheme (perhaps use the rod system posted previously by William)
Before I begin, can you give me a good guess (for this application) on the thickness and grade of aluminum for this?