Milling/drilling spindle

[Steve CrowParticipant @stevecrow46066]

Thank you Jason, that is just what I'm looking for. You are right about the round body, I think one inch square is the way forward.

Much as I agree with Michael's suggestion to use my existing headstock, I do feel the urge to make one from scratch.

By the way, if that is what you call a "quick sketch", I'm hugely impressed!

The spindle book is on order.

Cheers

Steve

[Steve CrowParticipant @stevecrow46066]

Hi all, another spindle question.

As for the bearings, metal or rubber shielded?

Cheers

Steve

[Kiwi BlokeParticipant @kiwibloke62605]

Bearing shields (metal) and seals (rubber) supposedly serve two purposes, although not necessarily at the same time – it depends on the situation: keeping the muck out and keeping the lubricant (usually grease) in. Metal shields are obviously more robust, thus better at excluding swarf and chips, but there is a small gap between shaft and shield, so dust and fluids can enter the bearing and lubricant can escape. Seals usually contact the shaft, thus will exclude liquid and fine solid contaminants and do a better job of containing lubricant. However, seals wear and also can exert so much drag on the shaft that low-torque drives may be unable to achieve desired spindle speeds. The drag can be quite surprisingly problematical. There are so-called 'non-contact' seals, which look identical to conventional rubber seals, but are drag-free. These are ideal for low-powered spindles, such as Unimat headstocks. Manufacturers' data sheets will give you the relevant identification numbers, etc.

Incidentally, for precision spindles, if using deep groove, rather than angular contact bearings, you should be looking for 'tight' bearings, with a small clearance rating. These may not be as easy to obtain as C3 or CN rated bearings (excuse me if I've got the wrong rating codes here – working from beer-addled memory tonight…). Lower numbers are tighter. Some manufacturers offer 'electric motor' bearings, which are designed to run more quietly, ie with less vibration, which is just what you want. They are not much more expensive than 'cooking' ones.

And, of course, buy quality, not cheapest.

[FarmboyParticipant @farmboy]

Some time ago I made a fairly heavy duty spindle using tapered roller bearings with rubber seals. All seemed well until it came to driving it. I tried a 150W grinder motor but the low starting torque would not overcome the drag even if given a helping hand. Lubricating the seal didn't help. It worked fine when driven by the lathe chuck as I machined the ER16 internal taper with the spindle running in its own bearings.

Still work in progress . . .

Mike.

[John Wright 19Participant @johnwright19]

Seen the posts here about milling spindles.

I recently made a new internal cassette for a Potts milling spindle I bought using a ER16 long size and made a new outer for it that houses 2 angular contact bearings that just fit the ER16 tube and the machined outer recess. I fitted 2 spring washers so there is a very little end float. I made a new mount that clamps around the old Potts spindle to take the motor and fitted a 3 high power 3 phase servo motor with the encoder disabled and it runs via a very cheap 3 phase power unit off Ebay. The motor is not really designed for continuous running like this so I cooled it with a finned jacket that reduces the temperature so it does not overheat. The motor runs nice and cool and with variable speed ands can run either direction. I have cut large clock wheels like this. The Potts is a great piece of kit and I can use it on either my Boxford lathe or my Rivett lathe. I can change et up of the spindle quickly to drill or mill or index if I want to use the cutter in the lathe.

Hope this is of interest

John

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