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  1. #41
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    Default Re: Weldon air spindle

    I spent a little time with this project today; learned a little.
    The spindle can be cut with a carbide insert. At 400 Rpm I did a tiny nick cut, the chip ribbon lit up bright red, cooled to a nearly black. The cut was very smooth looking.
    I drilled out the housing air inlet from #53 drill size to 1/8" NPT thread size. I hooked up air then to check and observe any change. There was an improvement, but certainly no floating.
    I dribbled some oil at the junctions of bushing and spindle and learned quite a bit. Air is coming out at the bottom of the spindle even at fairly low pressure, so it is being pinned to the top. Also there is quite a bit of air leaking from around the outside of the bushing
    Ozzie



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    Default Re: Weldon air spindle

    Yes.....you will get air leaking from around the outside of the bushing as it's only press fitted in the housing..........mine is a press fit I think as there is no apparent way to keep it in the body.

    When you get it to work you could assemble the bush to the housing and put a dab of thick grease on the outside.....this will stop the air from leaking and still allow you to remove it if necessary........I wouldn't use any sealer that goes hard or the bush will be impossible to remove without damaging it.

    DON'T DO ANY MACHINING ON THE SPINDLE.....IT'S AS GOOD AS IT WILL GET AND HAS A FINISH THAT WON'T RUST..

    My opinion is.....the TIR you got for the spindle is irrelevant............I would suggest that as you have the bush out of the body you could do a modification and make it the same as mine......this would be my way if I was in the same position.

    That is.......set the bush up in the lathe as truly as you can get and cut an undercut in the middle of the bore about 40mm long to the size I measured on mine......approx 1mm deep should do the trick.

    I'm sure this is the way to make the spindle float in the bush as it's a sort of gallery distribution chamber for the air to bleed past the spindle at both ends.

    You'll have to ensure that the air does get to the middle part from the outside hole......mine has a hole in the top of the bush (that is plugged) but it also leads internally to the side hole from the cut outs in the bush OD.

    Basically, the side hole on mine was probably for the handle to tilt it but got used for the air inlet too

    Why the bush didn't have a groove all around the outside to match the side hole to get the air in I can't imagine.

    Today, some time, I'll remove the spindle from my CUTTERMASTER and have a gander up the bush bore to see how it looks compared to the Weldon.

    BTW.......with all this work and fun and games.......are you intending to sharpen your own cutters?

    If you can get the Weldon to work you'll be right on the money as it's a piece of cake from that point on........it'll need a few mod add ons and a bench grinder to make a T&C grinder but that is all.
    Ian.



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    Default Re: Weldon air spindle

    I have a T&C grinder along with some fixtures. For the time I've had it I've done little grinding. I have everything to enable me to sharpen cutters, I just thought having a working Weldon would be neat. I also have a few dozen cutters that should be sharpened, both HSS and carbide.
    From these communications it is clear to me that the bushings that we have are very different.
    My bushing has an internal undercut, maybe 1 1/4" wide, not very deep. I think yours is the same.
    Mine did not have any holes in it for air. I made a passage in the bottom to line up with the air inlet in the bottom. Air now flows freely to the inside of the bushing.
    From what you've said, your arrangement has air entering the inside of the bushing from the top.
    In my case it appears that the rush of air coming in from the bottom pushes the spindle up with too much force even at relatively low pressure.
    This leads me to think that yours has more than one place for the air to enter the bushing. It might be hard to see.
    It would help me if you would put air through your unit with the spindle removed and feel where air is entering.
    Thanks,
    Ozzie



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    Default Re: Weldon air spindle

    Hi, just a few notes on the other air spindle on my CUTTERMASTER.

    I pulled the spindle out and inside there is a long bush like the Weldon.

    The difference is in the bore..........about 50mm in from each end there are three 8mm diam holes spaced round the inside of the bush and through it.

    By observation it is apparent that there is a groove around the outside of the bush that the 3 holes are drilled into.....this is the same for both ends.

    The air entry is in the back side of the body and in the middle of the bush.

    It goes without saying that the two grooves are linked by a cross groove that has the air entry hole leading to it.

    This is different to the Weldon design but works the same way as the spindle floats without any friction.
    Ian.



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    Default Re: Weldon air spindle

    Quote Originally Posted by ozzie34231 View Post
    I have a T&C grinder along with some fixtures. For the time I've had it I've done little grinding. I have everything to enable me to sharpen cutters, I just thought having a working Weldon would be neat. I also have a few dozen cutters that should be sharpened, both HSS and carbide.
    From these communications it is clear to me that the bushings that we have are very different.
    My bushing has an internal undercut, maybe 1 1/4" wide, not very deep. I think yours is the same.
    Mine did not have any holes in it for air. I made a passage in the bottom to line up with the air inlet in the bottom. Air now flows freely to the inside of the bushing.
    From what you've said, your arrangement has air entering the inside of the bushing from the top.
    In my case it appears that the rush of air coming in from the bottom pushes the spindle up with too much force even at relatively low pressure.
    This leads me to think that yours has more than one place for the air to enter the bushing. It might be hard to see.
    It would help me if you would put air through your unit with the spindle removed and feel where air is entering.
    Thanks,
    Ozzie
    Hi......only one hole in the top of the body that has a plastic plug in it.......but there are some sort of cuts in the bush OD like yours that appear to be connected to the air inlet point in the body......air comes out of the top hole with the plug removed.

    So, the air enters through the side hole at the bottom of the bush.

    Looking down the hole in the top and you can see 2 cuts in the OD of the bush.

    There is only one hole in the inside of the bush undercut and it is probably connected via the cuts in the outside of the bush to the air inlet.

    This is a strange design as it would have worked just as well with a groove all around the OD of the bush instead of the cut in it's OD.

    I don't think the inrush of air has anything to do with it as the air flow rate would make the inrush very small indeed once the pressure builds up.

    It's difficult to connect any air to the device as the side hole is 7/16" UNC and the top plugged hole is 5/16" UNF....I don't have any fittings to connect to the top hole........it came with a short barrel nipple threaded for 7/16" UNC in the side hole and a Nitto pipe fitting into that.which I connected the air line to.
    Ian.



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    Default Re: Weldon air spindle

    Photos Ian, photos!

    Cheers
    Roger



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    Default Re: Weldon air spindle

    Again I spent just a short time today with the Weldon.
    I cut a shallow groove around the outside of the bushing, centered. I drilled a hole through the bushing wall at the top. After cleaning and reassembling I connected air and there was some difference. The spindle did not get stiff until I got the pressure up beyond 80lbs. That seems to indicate that the location of the air inlet has some effect.
    But another thing I noticed is that the air leakage location changes radically as I move the spindle in various ways.
    Since the diameter I measure is constant within a couple tenths along the length of the spindle, but I get runout when mounted on the lathe that is greater in the middle, the thing is definitely bent. I doubt that this spindle in this condition will float.
    I'll give this spindle and bushing one more shot. I'll plug the holes I made first off with JB Weld. Then I'll drill new holes so not so much air comes in the bottom. That's easy so I'll try, but I think I need to make a new pair.
    Ozzie



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    Default Re: Weldon air spindle

    A bent shaft would not work very well - but how would a shaft like that get bent???



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    Default Re: Weldon air spindle

    Hi, just had a more closer look and it appears that there is an annular groove around the OD of the bush.....also there are 2 holes through the bush undercut, not 1 as I previously said.....one on top at 12 o' clock and another one at 9 o' clock looking at it from the back end.

    The top hole and the new side hole I found in the bush are connected to the annular groove.

    The side air entry hole in the body is connected to the annular groove near the bottom of the bush.

    Did a test with air to see how low it could go and it will still work at 30 psi.......also at 80 psi
    Ian...



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    Default Re: Weldon air spindle

    Quote Originally Posted by RCaffin View Post
    Photos Ian, photos!

    Cheers
    Roger
    Hi....just took some pics with my Iphone.......just gotta work out how to get them onto my PC......I think I'll try sending them as an email to my PC.

    The files from my camera are too big to post at 1.5Mb and my copy of Photoshop 7 for down sizing won't load onto Win 10.....there must be another way.
    Ian.



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    Default Re: Weldon air spindle

    The horror of it all - can you use MS Paint?

    Cheers
    Roger



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    Default Re: Weldon air spindle

    Roger, please read the first post. 4 tons of pressure and heat.



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    Default Re: Weldon air spindle

    Quote Originally Posted by handlewanker View Post
    Hi, just a few notes on the other air spindle on my CUTTERMASTER.

    I pulled the spindle out and inside there is a long bush like the Weldon.

    The difference is in the bore..........about 50mm in from each end there are three 8mm diam holes spaced round the inside of the bush and through it.

    By observation it is apparent that there is a groove around the outside of the bush that the 3 holes are drilled into.....this is the same for both ends.

    The air entry is in the back side of the body and in the middle of the bush.

    It goes without saying that the two grooves are linked by a cross groove that has the air entry hole leading to it.

    This is different to the Weldon design but works the same way as the spindle floats without any friction.
    Ian.
    Ian,
    Are these holes in the surface that touches the spindle, or in an undercut?



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    Default Re: Weldon air spindle

    Hi.....on the Weldon the holes go through into the undercut.......but on the CUTTERMASTER there is no undercut, just a straight bush and it has 3 rows of holes (120 deg spacing) at each end about 50mm in from the ends.
    Ian.



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    Default Re: Weldon air spindle

    Thanks Ian



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    Default Re: Weldon air spindle

    Hi, about 2 weeks ago I did an exercise measuring the bore of the Weldon bush with a telescopic gauge......I could have used an inside mike with the long rod to get down to the middle of the bore for a comparison test but the tele gauge was nearest to hand and I got too lazy to reach further for the inside mike set.

    But, you can also dial up an inside mike easier than slackening a tele gauge and pressing it in again and again to get a size.......BTDT.

    Unfornately, a "normal" or standard set of inside mikes starts from 2 inches or 50mm.....tele gauges do go much smaller.

    I also have a set that goes down to 1" Imperial, bought at an auction

    If I had to do more of the deep hole diam measuring then I'd invest in one of those bore gauges with a dial indicator as you can get a better position for the exact diam size due to the 3 point fit without being a smigeon off centre and getting a loose size like with the tele gauge, apart from being able to go much deeper into the bore.

    Gonna have a look on EBAY to see how much they go at and the size range they cover.....might make diam measuring in long bores a whole lot easier as you can instantly detect a slow taper or ovality.
    Ian. .



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    Default Re: Weldon air spindle

    Just had a look at the deep hole bore gauges on EBAY........cost approx $50 to $60.........the bad news is they only go down to 50mm diam so are limited to the larger bore sizes.

    Looking deeper in to what they are and it appears they are bore diam comparators and not actual bore measuring devices like a micrometer.........no apparent means to set them to a definite bore size to do a measure etc unless you have a ring gage to set them to as they are 3 point devices.

    I think they would be good to test a deep bore for taper and ovality.....but as for actual measuring the diam I don't think it will do the job.........unless it is first calibrated to a diam with a ring gauge and as the range on the dial indicator appears to be 1mm that is a difficult situation given the number of ring gauges required for the total range of 50mm to 160mm.....and a micrometer cannot be used to set the range either......it has to be a ring gauge.......oh well...sigh.

    I suppose you "could" measure the front of a bore with a tele gauge or inside mike to get the size and then do a comparison test down the rest of the bore once you know what the size is at the start.........a cheap ring gauge of sorts.,......... so it's just a comparator......hmmmm, another tool for the collection if you only do lots of deep hole boring.
    Ian.



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    Default Re: Weldon air spindle

    Quote Originally Posted by handlewanker View Post
    Just had a look at the deep hole bore gauges on EBAY........cost approx $50 to $60.........the bad news is they only go down to 50mm diam so are limited to the larger bore sizes.

    Looking deeper in to what they are and it appears they are bore diam comparators and not actual bore measuring devices like a micrometer.........no apparent means to set them to a definite bore size to do a measure etc unless you have a ring gage to set them to as they are 3 point devices.

    I think they would be good to test a deep bore for taper and ovality.....but as for actual measuring the diam I don't think it will do the job.........unless it is first calibrated to a diam with a ring gauge and as the range on the dial indicator appears to be 1mm that is a difficult situation given the number of ring gauges required for the total range of 50mm to 160mm.....and a micrometer cannot be used to set the range either......it has to be a ring gauge.......oh well...sigh.

    I suppose you "could" measure the front of a bore with a tele gauge or inside mike to get the size and then do a comparison test down the rest of the bore once you know what the size is at the start.........a cheap ring gauge of sorts.,......... so it's just a comparator......hmmmm, another tool for the collection if you only do lots of deep hole boring.
    Ian.
    I'm almost 80 and just a hobby machinist. My daddy was a tool maker in the late WWII days. I believe he would have measured those bores with a inside spring loaded caliper with finger nut. I still have his calipers and and micrometers, mostly Starret stuff.
    Anyway I just thought that would be an interesting side note.
    I did a little work/play on the unit.
    I filled the bottom hole in the bushing which was ragged and actually several small holes with JB Weld. I then recut the exterior groove which had some JB in it. I then drilled two more holes, at 4 and 8 o'clock, ( there already was one at the top). I did these with standard 1/4" HSS drills. Interestingly they went halfway through easily and then hit harder metal. Evidently the torch work I had done partly annealed the bushing. Slowing the drill press and using some oil I got through, buggering two drills along the way.
    All of that accomplished nothing!
    At low pressures the spindle is about like no pressure, but as I get up to about 20 lbs it becomes harder to spin and at 80 lbs it is pretty well locked up. All of that is hard to understand. With grooves around the inside and outside along with 3 1/4" holes going through, I find it hard to believe the spindle is being pushed to one direction with enough pressure to lock it.
    I've put it aside for now and turned my attention to one of a half dozen other things I'm working on.
    I'm thinking new shaft, or remade shaft or bushing or both. I have stock laying around to make either or both; solid stock for the bushing and surprising, a piece of steel tube the perfect size to make a new shaft. Machining the old shaft is a possibility, the bend is only a few thou. but it's pretty hard and I wonder about it pushing as I get to the middle; and/or it wearing an insert before finishing a single pass.
    Before doing any of that I think I need to understand what is happening with the way it is now! How can higher pressure lock the spindle? I can understand it not floating, but what is happening to lock it up?
    Ozzie



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    Default Re: Weldon air spindle

    Hmmmmmm.........I pondered this problem too as it's a puzzle due to the "design" that now is and looks a lot like mine.....well in the layout of the holes and bush.

    The bush most probably is cast iron and may have been subjected to a flame hardening process like they do to lathe beds.....that would explain why it's so hard.

    There are drills on EBAY under the name of ARTU that will drill the hardest of hardened steel items.......like files etc.......demos on UTUBE to show how they work......they're also advertised on TV under the RENOVATOR brand......contact phone no, 1800 100 005

    I have a sneaking feeling that you need to make sure the bush is sealed in the housing as it may be leaking the air away on the outside more than past the spindle and bush

    I'm thinking on those lines as there is very little air passing the spindle and bush bore when it's working.........it is possible that if the air leaks past the outside of the bush it won't do the necessary on the inside........this is a thinking solution, but could be the reason for no joy.

    Hypothetically.....the increasing air pressure acting on the outside of the bush "might" be causing it to close in a few tenths....sufficient to make it tighter the more pressure you apply.

    With nothing to lose..... in the end.......you could coat the outside of the bush with gasket sealing compound, something like PERMOSEAL (available from most auto supply outlets) that goes on with a brush, remains active and does not set hard.......this is a last ditch stand as it's also likely to get into the holes around the bush and bung them up.

    Making a new bush that is dead parallel in the bore is a task not easy to do as you will need to line bore it..... not bore it in the lathe per se, as most if not all lathes will turn taper to some degree............lapping the bore parallel with a split bush and grinding grit will probably work but honing with a cylinder hone works better.......you don't need to harden anything for an air spindle to work, but surface finish needs to be almost mirror finish..

    BTW........if I last to the end of the year I'll have a birthday cake with 80 candle on it.....gonna call the CFA on standby in case it gets out of control.....LOL.

    My father was a tool maker too....served his time at Woolwich Arsenal in UK between the wars....he passed on in 1977,

    I'm a fitter and turner, retired since 2002, but still mess with the machinery I've accumulated......doing the CNC thing now as a hobby as I've always wanted to watch the wheels go round with a computer doing the thinking.
    Ian.



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    Default Re: Weldon air spindle

    I too have had the thought of the pressure shrinking the bushing but dismissed it, thinking "no way". I've also had the thought that air passing around it might lower its temperature a few degrees and shrink it.
    With the new arrangement of holes, there is no way that the spindle is being pressed to one side of the bushing enough to lock it.
    If pressure is shrinking the bushing, sealing the ends won't help.

    The nipple that carries air into the housing is about 4 inches long and the hole in the bushing is larger than the nipple hole.

    So, I need to calculate the area of the nipple through-hole.
    Then measure the area of the cross section of the external groove of the bushing, and if needed, enlarge it to at least the area of the nipple hole.
    Next calculate the total area of the holes passing through the bushing and enlarge them if needed.
    With that done, if pressure still locks the spindle, it is time for suicide, or at least a frontal lobotomy.

    Boring a straight hole, no taper, is not easy but can be done. I've been able to do a smaller hole about 4" long with 0.0002" accuracy, as close as I can measure. I used a sharp pointed carbide brazed boring bar, very slow feed, and RPM slow enough to eliminate any chatter.
    Setting up for line boring on my lathe would be a tough one. How would I get the height right? Hmmm, maybe a couple adjustable parallels. It would still be a lot of dorking around.
    Ozzie



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