[jdurkin]

Yup the motor change is a kinda biggy alright but it really boils down to your machining requirements.....Aluminium and Alloy's higher RPM's.....Steel and Stainless lower RPM's....and if you're going down the belt driven route will you want to use L-Belt or Multi Ribbed timming belts and I believe looking at one or two other posts If my understanding is correct a good speed for finishing not roughing is up around 6,000 - 8,000 RPM for Aluminium but don't forget that at that speed you'd probably want your flood coolant all hooked up and also you will need to upgrade your stock spindle bearings too as if they're the same as the BF20 NSK's their max RPM is 3,500 approx, either way a spindle bearing upgrade is really a kinda must I recon as the Anguler Contact (AC) bearings can withstand far greater side loading forces as opposed to the stock tappered roller bearings and the AC have a higher max RPM and greater accuracy (run out) too.....

Great reply for me Mad Welder.

Material and Speeds:
Alloy will be my main material, Yes I was thinking up in the levels of around 6000 RPM and if Ive got this correct was in my mind a motor with around 3-4K RPM and having a 2 to 1 ratio on the belt to get it to 6-8K and also a 1 to 2 for lower speeds but need to look into this as also I need lower speed as I will be wanting to do lots of CNC tapping with maybe a reversable tapping head such as:
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but the max speed on this is 1500RPM

also tormach do one:
Auto Reversing Tapping Heads | Tormach LLC | We provide personal small CNC machines, CNC tooling, and many more CNC items

Coolant:
Im going to do my very very best to stay away from flood coolant
A mist coolant is what Ill try first such as:

Google Translate

Patent US5390854 - Coolant spray system - Google Patents

When my mill is up and running Ive got my eye on a compressor on ebay:
eBay - The UK's Online Marketplace

I know it may not be a pro compressor but guess its a start.

Bearing:

Yes this is a must and the first step for me - bookmarked the site where you got yours.

Thoughts welcome mate................


PS. Ive just started selling drill bits so shoot to my ebay and pick a dozen or so for yourself and Ill post them over to you free mate:
HSS Drill Bits, Blacksmith Drill Bits items in hss store on eBay!

John