Material/Manufacture of new lathe spindle

[RainbowsParticipant @rainbows]

Hey this seems familiar

Here is the spindle I want made, currently missing some details like preload thread/keyways but gives general idea. Lathe has a ~90mm centre height

I was wondering what material I should use along with the manufacturing process.

I have access to a DMG Mori Ecoturn which could hog out material and use live tooling to cut the holes in the faceplate. General accuracy on that lathe is 0.005mm.

My original plan on materials was EN24T. A 30mm bar making the shaft with a large slice to make the flange. Not sure how to attach the flange. Welding? Interference/shrink fit? Read that EN24 doesn't weld readily but I don't know how much torque transmission I can get with a shrink fit.

Bearing in mind the 0.005mm accuracy and high surface finish of EN24 would sending it out for cylindrical grinding be overkill? Would have to have grinding outsourced. Was also considering hard chrome or electroless nickel plating but again unsure if overkill.

Last question was how to drill a 260mm long 20mm hole. Have a vague idea of using a boring bar with a hardened bush so that it is guided by the previously existing smaller hole but would be happy to hear what other people have done to drill deep holes.

[RainbowsParticipant @rainbows]

[Bill PudneyParticipant @billpudney37759]

If it was mine I would make it out of 4140 steel, I believe that is close to or equivalent to the EN24 you suggest. Make the flange from the same spec material, incorporate a shoulder for axial location, and a couple of pins for peace of mind. High strength Loctite (609 or modern equivalent) would hold it with no problem. Finish turn flange after joining if required. If drilling/ boring the hole doesn't seem feasible get it EDM'd. The machine quoted should be able to do this without needing grinding.

Best of luck

Bill

[JourneymanParticipant @journeyman]

Easier to buy one of these

John

[Tony Pratt 1Participant @tonypratt1]

I would go for EN24T or similar & make from one piece. The lathe DRO might give a resolution down to .005mm but I seriously doubt the part will finish up to size & parallel over it's length to that sort of limit, if you want the best finish etc. grinding is the way to go but obviously costs.

As always you pays your money & gets your choice.

Tony

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