Spin indexer

[Darren]

Is this our John Stevenson?

http://www.arceurotrade.co.uk/Catalogue/Collets/5C-Fixtures/Stevensons-5C-Indexing-Head-with-ER32-Nut-and-Adaptor

[rleete]

No, that's an indexing head.  I doubt John looks quite so metallic.   

[Darren]

The way his name gets all over the internet with almost anything metal orientated I wouldn't be so sure 

[Darren]

I'm looking at finding a way of touching up endmills properly, the spin indexer would prob be ok for doing the ends but not the flutes.

For this everyone seems to suggest an air bearing device is what's really needed. The problem with other ways is any roughness (even with high quality bearings) will result in the flutes being notched. Not good unless you just want to use it for roughing I guess.

Then I came across this, interesting idea. I wonder if it would work?

[John Stevenson]

Darren,
Granted an air bearing attachment is, in theory better than a plain bearing but I do have to wonder just how many who repeat what they have read have actually used one ?
I have seen designs on the web where because of design limitation they will not work any better than a plain bearing, which is in fact how they are operating but the owner reckons thay are the best thing since sliced Warburton's.


I personally can't compare as i have never used an air spindle, however when i did my apprenticeship all the machining apprentices used to have to run the gauntlet of tool and cutter grinding.
In fact they had to do all of it as T&C grinding didn't pay bonus as as we couldn't earn bonus we got the lot, and whoa betides anyone who shagged a cutter or reamer up.

We used a motley collection of machines, Clarskon's Alexandria's and many more with no name on them. Most had served through two World Wars, seven earthquakes and even an uprising of the Women's Institute, [ Huddersfield Chapter ]
All had plain bearings, all were shagged but they could still turn a good job out with a little skill.

Personally I feel that there is more crap talked about tool and cutter grinding than any other home shop subject. It's one of those no win situations as everyones needs are different.

Anyone fancy telling a Quorn owner it;s crap as it doesn't have an air spindle ?  

[Darren]

Thank you John for your reply,
It never ceases to amaize me how much bull is spouted as gospel between so many different types of interests.

I have read quite a bit on endmill sharpening and everyone seems to contradict. This makes it hard to use any info out there.
I guess you have a spin indexer...how smooth are they...smooth enough to do this task?

I have seen this, price not too bad, but no info, no mention of what the bearing type is. I guess at that price it's not air. 

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&ssPageName=STRK:MEWAX:IT&item=360056332883

[rleete]

We use custom designed vertical lathes with air bearings for the diamond turning here at work.  They are cutting masters for optical lenses, and nothing else will do for the accuracy we require.  The air bearings are about 20 grand to replace.  I believe the clearances in the bearing are on the order of .00005" or less.

Then again, these are very specialized machines, and designed to hold tolerances that would astound most people.  Most stuff is cut with angles held to seconds of arc, and depth of cut in the micron range.  The cutting tools alone cost more than most of us have tied up in all our tooling/fixtures combined.

[bogstandard]

I was only on about this to Darren the other day. It isn't the grinding head that is usually the problem, it is holding the tooling in the correct position to do the grinding that is the main problem.

I have used air bearing grinding machines that easily hold micron tolerances, but my old 1950's Herbert surface grinder works wonders at times. I grind all my own HSS lathe tools up on it, and I am sure if I put my mind to it, I could grind all my milling cutters as well.

I wouldn't really trust the bearings in a motor to run a precision grindstone, but it is easy to make a spindle up with no end float, and belt drive it from that motor. That is all a toolpost grinder is, and the spindle on mine is plain bearings, as long as they have the film of oil to run on, and no end float, they are perfect for the job.

John

[sbwhart]

I personally can't compare as i have never used an air spindle, however when i did my apprenticeship all the machining apprentices used to have to run the gauntlet of tool and cutter grinding.
In fact they had to do all of it as T&C grinding didn't pay bonus as as we couldn't earn bonus we got the lot, and whoa betides anyone who shagged a cutter or reamer up.

We used a motley collection of machines, Clarskon's Alexandria's and many more with no name on them. Most had served through two World Wars, seven earthquakes and even an uprising of the Women's Institute, [ Huddersfield Chapter ]
All had plain bearings, all were shagged but they could still turn a good job out with a little skill.

Personally I feel that there is more crap talked about tool and cutter grinding than any other home shop subject. It's one of those no win situations as everyones needs are different.

Anyone fancy telling a Quorn owner it;s crap as it doesn't have an air spindle ?  

Her Her John

We had a similar situtation when I was an apprentice we got all the cutter grinding most of the machine were war finish or lease lend.

I remember when I was just out of my time and the tool room was short of work the forman told me to go in the stores and sort out 50 shagged slitting saws and sharpen them up and he would get a piece work price for me, so I sorted all the saw that were close to the same size and the same number of teeth then put four or five on one mandrel and sharpened them all together I had a good bonus that week. 

Darren

I'm just in the process of gathering together the bits to make a cutter grinder, not sure if it will be any good, but I'll post the thread in a couple of months time when I've got one or two other projects out of the way 

Have fun

Stew

[Darren]

I will look forward to that one Stew as it's something I'd like to make....

[Darren]

If I was over there....this would be on it's way by now.

Just a little too much to post to the UK me thinks.....

http://cgi.ebay.co.uk/CINCINNATI-2-TOOL-CUTTER-GRINDER_W0QQitemZ290321819030QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item4398876596&_trksid=p3286.m63.l1177&_trkparms=240%3A1318|301%3A1|293%3A1|294%3A50

[sbwhart]

Darren

My Dad use to work with one of those:- boy could he make it sing.

First class machines you can do all sorts with them.

Stew

[raynerd]

Just to bring this post up from the dead -can anyone explain how this differs from a dividing head? I believe it is not possible to cut "wierd" numbers/divisions on them so does this mean that the indexing plate can not be changed? Just a little confused about how these are used and why they would be used over a RT or dividing head.

cheers
Chris

[John Stevenson]

They are basically cheap and cheerful bits of kit, more suited for quick repetitious jobs on simple indexing.

They work in degrees so any number that can be divided into 360 is fair game, mind you noting to stop the plate being swapped for one with direct indexing.

I feel these are very under rated bits of kit.

You see a spin indexer,

I see tools and cutter grinder.



Cheap and cheerful X Y table, spin indexer, tilting bracket and a bench grinder and you have the basics of a T&C grinder.

You see a spin indexer,

I see a stepper controlled 4th axis



Spin Indexer, stepper motor and the reduction gearbox off an electric motor and you have any division or angle you need.

John S.

[raynerd]

Cheers John, excellent ideas.

So it basically a cheaper dividing head?