Air Spindex - shop made spindle

[goodscrap]

this is still work in progress, but here is my spindex converted to run on air, i read lots on the net to say it wouldn't work, but i had to proove them wrong

i'm in the process of making various attachments for a clarkson (or march in the us) cutter grinder, i'm half way through making the attachment for releaving the flutes, i used a spindex for the bulk of it, but after completing the finger follower i felt the resistance from the spindle was a bit too much, so i've drilled the spindex for air, i did a test run this morning and while i've still got a lot of tidying up to do to make it a proper job, the spindle works better than i expected.

on 15psi of air it floats, but if you push down on the cutter the resistance becomes more than desired, on 30psi it will still extend smoothly with quite about 10lbs of hand pressure.

it will run for a long time, i set it spinning, went to get a cup of coffee and my camera to shoot a video, i returned some 8 minutes later and it was still happily spinning.

hopefully this link should be a video of it in operation

http://s182.photobucket.com/albums/x295/cov_climax/?action=view&current=spindexairbearing1.mp4

i drilled the holes into the bore and was careful to back spotface them all to the same size, as this area is what gives the balancing effecto on the spindle. i took some 600 grit paper to the bore of the spindex by hand, but didn't achieve any great improvement

also the tube fittings in the distrubuiton block have different size orifice sections to give a bias to the lower ports, to offset the weight of the spindle, no calcs were done for any of this.

it probably justifies a better write up than this, but i thought i share it regardless, i'm well happy with progress so far

Brian

[Peter.]

I like it! Will you swap out the huge air lines for something less bulky when it's all done?

[strokersix]

A neat job with bent hard lines would look sharp and be least obtrusive.

[etard]

Very cool! Is this to be used for gear hobbing? What exactly is the point of this being run on air? Sorry if this is obvious to others...

[huntinguy]

Very cool! Is this to be used for gear hobbing? What exactly is the point of this being run on air? Sorry if this is obvious to others...

Air balls are smaller than steel balls, are more uniform in size so they have less run-out and have very little friction compared to steel balls.

I need more coffee before I start my day... but it is all true.

[dian]

extraordinary! so you have only 6 holes in there? is that all, or did you machine the casting for the air to escape?

[goodscrap]

Yes, just 6 holes, one was the original locking screw position on the top. The others were drilled, spot faced on the bore side to be al the same size/area, then tapped for the fittings. There are no internal grooves and the spindle clearance is as it came out of the box,.

Pipes will be replaced by smaller, but will have to be flexible for the thing to tilt when fitted to my cutter sharpening rig that is in construction.

Brian

[vpt]

I don't get what it is supposed to do either. Is it supposed to go back and forth? What is "supposed" to spin it? Then what do you use it for after it spins and stuff?

[RWO]

For those that want to make an air bearing spindex, the process is detailed in HSM, Oct.'87 by Philip Duclos as part of his end mill sharpener for use on a surface grinder. I heard that the same info is published by Village press in the book, "The Shop Wisdom of Philip Duclos". I made the sharpener project from the original aricle and it works very well. Duclos' design for the air bearing spindle is simple and has only one external air inlet but does require some fairly deep holes in the casting.

RWO

[Ian B]

As I understand it, the spindle both rotates and slides back & forth. The OP mentioned a finger follower, which is a common way of keeping the helical flutes of an end mill etc in the correct position for grinding on a t&cg. The endmill is moved back & forth by hand, and the flute is kept on the follower partly by hand, partly by the grinding wheel.

As spindexers only normally rotate and don't reciprocate, I'd guess that the spindle is new. A ring can be seen at the back end to prevent overtravel.

Ian

[Rosco-P]

I took some 600 grit paper to the bore of the spindex by hand, but didn't achieve any great improvement
Brian

Wouldn't this be a case for precision lapping? Get the bore as straight, cylindrical and smooth as possible?

More experienced hands than mine, please weigh in on this idea.

[John Stevenson]

This is one of the spindexers supplied by ARC in the UK.
These are unique in that they take standard 5C collets and ER32's which are more common here and in Europe than the 5c's, note the ER closing nut on the front of the spindle.

Other than this it's the same spindexer as sold all over. They do spin [ hence the name ] and they can reciprocate but usually the 'travel ring' is close up to the back of the body.
In the OP case he's moved it to the end of the spindle so basically what he has shown in his post can be done to any of this type of spindexer whether sold by ARC in the UK or any of the US outlets.

It's a very neat and simple solution to get a working air spindle from what is basically a very cheap bit of kit. 11 out of 10 for effort.

Perhaps we could see more of the back spotfacing operation please ~?

[goodscrap]

yes, it's for a flute grinding attachment so i can sharpen milling cutters

Sir John got it spot on, ARC are just down the road from me so it's one of their spindexers, it's a good adaption with the ER collets.

if in was doing this again i would use smaller fittings (but maintain the spotface diameter as this gives the self centering force) you actually need less air than i though so 1/8" tube would be fine, be nice to some how use rigid tubes and braze them into the body so they formed their own distribution without the need for the external block, be easier to de-rig it all it for milling operations as i didn't plan for it to be a dedicated air-spindle .

anyway i though i'd get asked about the spotfacing op, before i stripped the spindexer i made a cutter, this was from a cheap wood bit, re-ground using the clarkson and spindex.

so i tilted the head to 30 degrees, mounted the spindex on the side of a machining cube, all set clocked in horizontal etc to the mill.

then i made sure the quill was centered over the quill and i had enough head room for all operations.



so i drilled a 6mm hole, which is the size of my drill rod manderil, on to which i then attached the home made cutter



I let the quill retract under it's own spring pressure with the cutter stationary then zero'd the dro


once the cutter was rotating i slowly retracted it until i reached enough of a counter-bore to remove any burr and also give clearance for the latter tapping operation, all holes were done to the same depth, then tapped afterwards, the pic below is before opening the hole further and tapping to M8 thread




Brian

[gzig5]

Very clever. Thanks for the pictures.

[Mcgyver]

yes, it's for a flute grinding attachment so i can sharpen milling cutters

i wondered as well, looks like you've got the air part working. Air bearings I have call for 100psi yet you can't really feel any air escaping, amzing things. How much axial motion do you have?