Sharpening end mills

[awemawson]

Pete,

I have a sensitive drill intended for PCB's sitting in a cupboard if you want to borrow it

 

[Pete.]

Nice one Andrew - that would be ideal for drilling some 10 thou holes though it doesn't look like it allows for a lot of clearance under the drill. My part is about 1-1/2" diameter.

 

[awemawson]

I'll see what it'll do Pete and let you know

 

[awemawson]

Headroom to chuck jaws is about 1.75" - I'm pretty sure that by temporarily removing the travel limiting plate that can be extended quite a bit, as that disk above the chuck is a smaller diameter than the Quill so should be able to go up into the quill bore

 

[Hopefuldave]

I will of course. I have started it actually, it's a scratch-built unit rather than a spindex conversion. I've spent a couple of evenings reading up and come up with a plan for a small distributed-orifice unit based on some induction-hardened rod in a cast iron liner but I don't have a sensitive drill to drill the tiny holes so I might have to go for bigger holes and suffer the extra air consumption.

I'm looking forward to the write-up, as I'd like to try building one! I borrowed the McGraw-Hill "Bearing Design and Applications" from the library at work (1957 edition, last loaned out in 1988...) and I'm working my way through the "hydrostatic bearings" chapters, the maths is a bit, er, challenging? Any info on the orifice size/layout would be Most Helpful! I too may need a sensitive drill to do it, or I *may* be able to sneak a Swiss Navy job in for EDM at work...

I have a 150mm piece of 50? mm stainless bar and another it floats in (Stavax, and in hardened state, probably not quite tight enough for a vacuum seal so into the skip they went...) - sat on a flat with grease around the bottom, the inner "spindle" floats on trapped air and rotates for a couple of minutes or so when spun by hand, slowly working its way through the bore, I'm hoping that's a close enough fit? I should be able to get 50 - 75mm of travel I think, enough for most of the cutters I can see me using.

What toolholding will you go for? at the mo' I'm thinking either ER32 or ER40 collets and boring the end of the "spindle" to take them / the locknut.

Dave H. (the other one)

 

[Pete.]

I'm just boring mine for the R8 collets I am using on the Clarkson. If they are not up to the job I will think of something else. My plan is to lap the shaft to fit the housing then shrink on a slug of EN40 and turn that to accept the R8 taper, perhaps finish-grinding it whilst running under power on it's own air bearing.

My main concern (apart from that it actually works) is that I can use it without my noisy old compressor keep kicking in. If I can't make it a good enough fit for that I will have to build a box for the compressor.

 

[awemawson]

Pete if it's any consolation, my air bearing for my Clarkson Mk 2 uses very little air

 

[Pete.]

I'll let you know if it's a consolation or not when I've built mine

I don't suppose you could measure the radial clearance on it with the air off could you Andrew?

 

[awemawson]

I don't think that I have anything accurate enough to do that on the bore - it will be be of the order of a gnats gonad or so.

 

[Pete.]

I was thinking perhaps a tenth indicator on top of the spindle right next to the housing and see how much up and down slop you could measure with the air off?

No matter if it's not feasible I was only curious about it.

 

[RichardM]

Getting rid of that green wheel for a nice AlOx wheel will make a huge difference for you.

Thanks Pete, I'll stick the AlOx cup wheel back on, when I sort the gash out I'll let you know how I've done it (if you haven't sorted it before).

 

[Brad93]

There’s a Clarkson on eBay at the minute for £375

 

[tom-madbiker]

I made a spindle for Grindin up end mills using a er32 spindle tried it a couple of times grinding flutes using my surface grinder works ok but need to practice a bit and set it up properly I was using a old ground up hacksaw blade to run along the spiral to do end tips I use my dividing head on the surface grinder