Over the past few days I’ve been reading through the custom build posts on the board looking for info on how people have been designing & building their spindle. I pretty much got information overload.
So, I still have some questions, which mainly come from my lack of knowledge of how industrial machine tools are built.
Any help on these will be appreciated. Thanks.
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I’ve read that the most recommended bearing setup in spindles is using two angular contact (AC) bearings (mounted either face-to-face or back-to-back) at the chucking end of the spindle. Then one or two high-radial load ball bearings at the pulley end of the spindle. The bearings are positively held a distance apart from each other by use of spacers or steps in the spindle housing that they are pressed against.
I’ve also seen some posts where all the bearing in the spindle housing are AC bearings.
Is there an advantage to using all AC bearings as opposed to a mix of AC and standard ball bearings?
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In one post it was mentioned that the high-radial load bearings on the pulley end should be a slip-fit on the spindle to allow for heat expansion & contraction in the spindle itself.
For all you guys that have worked on machine spindles, is that an actual practice??
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In the drawings of spindles posted the chucking end of the spindle has a face that is pressed against the inner race of the leading angular contact bearings.
This means that any force applied into the spindle (lathe cutting towards the chuck or drilling / plunge cutting in a mill) will be transferred directly into the inner race of the AC bearings. However, only the press fit of the spindle in the bores of the bearing handles the pull forces generated in a lathe when tool is cutting away from the spindle or in a milling operation with an end mill where the helical teeth of the end mill apply a downward force on the spindle.
Does there need to be something on the spindle shaft (like a threaded on collar) that positively locates the spindle to both sides of the AC bearings or is the one face against one bearing and the press fit of the two AC bearings enough?
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Are there generally seals between the Spindle and Spindle Housing (Head Stock) to prevent debris from getting into the bearings, or is something around a .010” gap enough to let the spindle turn and keep stuff out?
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A question specifically about lathe spindles; Is a VFD capable of being used to single point cut threads or does it require using a Servo for a spindle motor?
Thank you all for your time,
Curtis F.