Diy Brushless Spindle

[blackburn mark]

I would also load the angular contact bearing in the same orientation (both loaded with "upward" force). This would make the bearings strong in plunge operations, but weaker in operations where the bit is moving up out of the work piece. Would this be a problem though? Most operations are pressing into (down) the work piece.

on most occasions your tool would be pulling down as you are cutting but as i have said above, get some tension in those balls and and loctight your nose bearing and you should be fine

bearing heat may be an issue if your running above 10000rpm (keep an eye on the temp though as it may take a while for your bearings to settle in) if your cutting plastics and pcb's and your not in a crazy arsed rush then 10000rpm is a tad fast... i cut acetal at between 2000rpm and 4000rpm (6mm 3mm tooling) im sure i read somewhere that anything up to 110 degree C and your ok .... mine dont get anything like that hot

the small engraving spindle i made gets pretty hot when i run it above 30000rpm so i tend to run it closer to 20000rpm , i dont run that one very often so its hard to say how long the bearings will last?

[njhussey]

I'll reply to the rest when you've done a drawing...

Well I've had a look at the design and tewaked it a bit. Will probably do a MK2 spindle using this method or I might tweak this one I've already machined. this one is only really going to be cutting up to 6mm balsa and 3mm ply so I can't imagine the forces as being huge. I might stretch to some delrin/acetal and even try some Ali for a laugh



This shows the top collet (but I haven't bothered showing the grub screws) on the 8mm shaft which is pre-loading theinner races against the bottom collet. I'm guessing I could get away with not securing the bottom collet (locktite) as it will be trapped between the bottom bearing inner housing and the ER16 collet.



This shows the assembled unit (minus the bolts but we all know what they look like!!)



The bearings in the above are not spaced the correct distance, they will be a further 10mm apart so I can get some Bellville washers in between.

This design has the inner races locked to the 8mm shaft and the outer races are constrained by the endcaps...............comments?