Hello,
My first question here ever.

I have been toying with the idea of buying a QCTP and works for two lathes. I'll do that AFTER I have succesfully copleted this project:
I need some advice on spotting drill spindle design. I haven't build it yet, I have some material lying around, but I need to confirm few parameters.
Basic design considerations:
* Simple, no need to use for general drilling/milling with added complexity/weight/setup. I want it's spindle centre to lathe centre height and leave it there.
* Would be nice to able to use commercial QCTP boring bar holder. Most of the commercial tool blocks for my needs have about 1" hole.
* Therefore would be nice if I could fit spinle cartridge into 1" hole, least most of it. Then again I suppose I could bucher up one and machine it to acept slightly bigger bearings or build the whole tool block.
* Drills would be 3 mm or 6 mm (7 mm for M6 camfer) something like 95% of time. Drill Chuck or ER-collet? I have sope ER11 collets and they are neat. Chuck would be more versatile, but much bigger.
* I probably could aim to 6000-9000 rpm spindle speed, but I don't want to go very much over (motor/gearing/seals). Do I get away with only one spindle speed?
* I think I would get away with only one speed, maybe 3000rpm and 120w or 180w induction AC motor (I like it quiet)?
* I'd like to be able to mount it axially and radially to TP.
Spindle design (the major self made part):
* I have this one book about spindles, but I'm not completely happy with designs. Spindles (Workshop Practice Series No 27) by Harpit Sandhu.
* Closest of the design I like I have found is one with anglular contact ball bearings in this book: Lathework a Complete Course, number 34. ISBN 1-85486-230-8
Same design is also on MEW #80
MODEL ENGINEERS’ WORKSHOP
http://www.homews-mew-index.co.uk/index.html 80 12 LATHE PROJECTS FOR BEGINNERS14 MILL/DRILL SPINDLE C HALL
81 12 LATHE PROJECTS FOR BEGINNERS15 MILL/DRILL SPINDLE 81 C HALL
Not completely happy with this one either. I don't "get" the need for the first nut on the primary bearing. Bearing clearance is adjusted yet another nut and the thing is just a little of LLP design. (Lot of Little Parts). But I't closest I can get.
* I'd rather start with a good design than overly simple or fiddly. I'm allergic to ball bearings all over, I rather would but a small taper roll bearing, but they would kill small motor and would need additional shiels/seals. Should get away with angular contact ballbearings. Then again I don't want to go overly expensive/sensitive/accurate bearings, because of my track record: I probably blow up few before I learn my lessons.
Also I don't want build to a lesser standards you could buy from the shop...
Am I missing something obivious here?
PekkaNF