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Thread: Weldon air spindle

  1. #81
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    Default Re: Weldon air spindle

    Yes the Weldon parts are quite hard and amazingly the manual says that after the tool wears some you might need to increase the air pressure! Wear, what wear?

    I've thought about the machining
    If I'm starting with a solid I could turn the outside between centers, or start with an extra length piece.
    If I start with the bronze piece, I might be able to grab the inside of the hole. I'd probably need a way to support the outboard end; rig a plug with a center dimple.
    I have a tru-set six jaw that should work for the hole. My lathe is CNC'd so I can take a zillion shallow cuts to bore, or set up the steady rest. The bushing is only about 5.5" long, but these are soft materials.
    Later,
    Ozzie



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    Default Re: Weldon air spindle

    Well, due to the relatively thin wall thickness I would bore it roughly first as you can grip it quite fiercely......then rough turn the OD.........just end for end it.

    Put a couple of 60 deg chamfers in the bore ends when you rough bore it to mount it on a large centre bung turned in the chuck and a pipe centre if you have one for the tailstock.

    Then you can finish turn the bore to a couple of thou up

    The OD can be finished along with the annular grooves etc...... between centres on the bore ends should get you dead concentric.....BTDT.

    When it's pressed into the housing you can hone it or lap it to fit the spindle.

    Seeing as how the spindle "might" have a bend in it from the dissasembly........at this stage it might be a good idea to attempt a straightening exercise on your press with a couple of vee blocks and a dial indicator..........I had to do that with a 100mm diam shaft once that had 6mm of bow in it......you just do a couple of thou at a time and increase it until it gives.

    It's 4AM....gonna hit the sack before the sun gets up......ZZZzzzzzzzz.
    Ian.



  3. #83
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    Default Re: Weldon air spindle

    I got out there long enough to do a little.
    I turned the exterior bushing groove to over an inch wide and a smidgeon deeper. That means the air path is grater than the supply tube.
    I installed it and connected air, but still no joy in Mudville. There is no pressure setting where the spindle turns easier than with no air. Up to 40 or 50 lbs there is no difference, but as I go to higher pressures I still get lock up. Starting at about 50 lbs there is a large amount of air escaping between the bushing and housing. I guess it happens at all pressure but I don't notice it until the greater ones.
    The gap between bushing and housing must be larger, maybe much larger, than between bushing and shaft. I can see why that might prevent the shaft from floating, but I don't understand the lock up.

    Seal the ends. The only thing I had on hand is something called "tack and seal". I did the ends to a depth of about 3/8" in. I have no idea if it will work.
    I'll let it dry until Monday, (if it dries at all), and see what happens. If it blows out I think I'll try RTV sealer.

    According to Duclos there needs to be .002" for this system to work, but the measurements that Ian supplied showed much less, and I have about what Ian has.
    I tried covering the shaft with magic marker to discover any binding spots and couldn't get it in the bushing more than a couple inches. Squeaky clean it goes in easily. How thick can that marking be?



  4. #84
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    Default Re: Weldon air spindle

    The spindle is definitely bent, the only question is how much and is it a relatively sharp bend. Near the center i read .003 TIR, but in that same setup I was getting .0008" TIR at both ends. Both ends the same as close as I could read a tenths indicator.
    The setup was the shaft resting in two V-blocks sitting on my granite surface plate.
    How can that be? Maybe it's egg shaped?
    I suppose I could go through a whole mapping sequence, measuring at inch intervals and rotating every 45 degrees, buy I'd rather just turn a new one.
    The thing is it feels pretty good in the bushing without air; pretty good, not perfect.
    Good thing this is only a hobby!
    Ozzie

    Last edited by ozzie34231; 03-24-2018 at 05:46 PM. Reason: clarity


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    Default Re: Weldon air spindle

    Hi, if it doesn't have a significant bow in the middle it might be very difficult to "persuade" it back into straightness.

    As you have a granite table.....that is about the best surface to test it on......I'd lay it on the table and roll it around then run a dial indicator over the top......OK, so it's resting on the very ends but you can test under it too with a feeler gauge all along it's length as you roll it.

    As the spindle does go into the bush without difficulty it shows that there may be only a small amount of bend around the middle if any..........bending it back from a couple of thou would be hard.

    Now, if you have a tool post grinder......I missed a Walldown T/P grinder on EBAY at $250 as I forgot the time it finished, only one bid went through....sigh, more toys.

    That would enable you to take a couple of thou at most off the OD to make it true before you bore the new bush.

    I've used a poor mans tool post grinder once which was a piece of broken grind stone held in the tool post and applied to the high spot of a shaft to true it.....then polished with wet and dry.....when the Devil drives etc.

    One of the guys at a model club I used to go to in the late 90's used an angle grinder with a 100mm stone and a dimmer switch to drop the speed to 4,000 rpm........it worked and gave quite good results.

    I've also used an angle grinder with an adaptor and mounted points to grind the bore of collets in situ on a capstan lathe I had when I ran a small $50 business in the mid 90's.

    As there are 2 handle holes at the head end, mounting the angle grinder in a cradle on the lathe turret was quite easy........when the Devil drives again etc.
    Ian.



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    Default Re: Weldon air spindle

    The sealer is sticky right now, after about 20 hours. I don't think it will harden but it still might seal.
    Tomorrow I'll put the air to it, trying to remember to cover it; might blow out ugly.

    I don't have a tool post grinder and have been hesitant to build one because of the potential grinding dust damage to the lathe. I guess that can be minimized with a vacuum system.

    My T&C grinder has about a 12 inch travel and although that's not enough for the stock spindle, a shorter one should be fine for any flutes I might grind with the Weldon. So that's a possibility. I have several work heads for the T&C but the only motor driven one holds MT3 shanks so I'd need to rig a dog and run between centers. That's not a problem.
    I've never cylindrically ground anything longer than a few inches. I don't see why it wouldn't work. The machine is hundreds of pounds but not a thousand plus like my lathe.
    I've seen a great video on setting up for getting a grind with no taper.

    Well, hopefully tomorrow will show me something.
    Ozzie



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    Default Re: Weldon air spindle

    Yessssss........you might get away with grinding a spindle OD on the T&C grinder but the diam of the stone may not allow you to do a long length between centres without hitting against the grinding head.............cylindrical grinders have large diam wheels because of that problem.

    You might be able to slew the wheel head around a few degrees to clear the head and then dress the stone to make it parallel to the work piece.

    If you contemplated that option you'd have to grind the spindle first before boring the bush.......a practice run on a scrap steel bar is highly recommended.

    The wheel head on my K O Lee T&C grinder is just a double ended reversible motor....speed around 3.500 rpm so larger diam stones to clear the head are out due to the peripheral sped that limits it to 125mm max....slewing the head around slightly was one option I thought about some time back.

    I'm of the same opinion as you.....no grinding on the lathe whatsoever.

    Attached is a pic of the inside of the CUTTERMASTER bush showing the row of holes at each end.....the bore is highly polished so there are lots of reflections that might confuse.

    The first pic is of the Weldon device showing the cutter finger rest position.......if you haven't got this item on your Weldon it will give you an idea of how it looks in case you want to make one.
    Ian..

    . .

    Attached Thumbnails Attached Thumbnails Weldon air spindle-dscf1804-jpg   Weldon air spindle-dscf1801-jpg  


  8. #88
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    Default Re: Weldon air spindle

    Great picture looking own the Cuttermaster bore, Ian.

    I put air to my Weldon rig this afternoon but there is still no joy. Air escaped from one side of the housing-bushing joint.
    The spindle was harder to turn at all air pressures; the more pressure, the harder to turn. It was easiest and smoothest with no air.

    I removed the bushing using my press; very little force was needed. I cleaned everything with acetone.

    I decided to take very careful measurements of everything.
    First the housing. One end measured 2.125" bore and apparently round. The other end is 2.127", also round. That was the leaking end.
    The outside of the bushing 2.124", both end the same, both round.
    The inside of the bushing 1.6880, both ends, both round.

    The shaft.
    I took your advise Ian and set the shaft directly on my surface stone. The smallest feeler I have is 0.0015" thick. I attempted to insert it at intervals of about each inch along the length, then rotating the shaft a quarter turn and repeating until 4 quadrants were tried. There were no spots that the feeler would enter. Does that invalidate my idea that the shaft is bent about .003"? I don't know, hurts my head to think about that.
    I next measured the diameter of the shaft at 20- 30 places. All measurements were between 1.6870" and 1.6876". So, I have far less than 0.002" space between bushing and shaft.

    Jimmie and I went to the hardware store and bought some Permatex #1 gasket maker ,(hardening). and re-glued the bushing in place, this time rotating it in place hoping to get a better seal.
    I put it together, still with no idea how/why the shaft locks up under pressure, but thinking I don't know what else to do to the bushing. I think I need to fix or remake the shaft.

    I looked my T&C grinder and the stroke is more than 12" probably enough to grind the shaft. I need rotate the grinding head to know for sure.
    Ozzie



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    Default Re: Weldon air spindle

    Hi....if you can't see any gap beneath the spindle that a .0015" feeler will indicate when you roll it on the plate then it ain't bent by my reckoning.

    At .0015" over the length with the ends actually resting on the plate.......I would not worry about the spindle being anywhere near bent...........a .025 (.010") gap would be a different matter as that is a definite bend size.

    So.........first if you can seal the bush to the housing that would be an indicator of if the dang thang is going to lift off.....LOL.

    If you get the bush sealed and no air leaks past the OD of the bush then I would bet my family jewels that you'd start to get some results..........at that scenario yours is practically the same as my device.....all holes being functional of course.

    Once the device is working as should.........I doubt you will ever grind cutters again with the T&C table movement .....it's that smooth and sensitive.

    Of course you will also need to fit a cutter holder into the end of the spindle as mentioned way back..........an ER32 chuck with a plain 1 1/4" shank, if you can get one, or a Metric one ground down a thou or two would be good.......it won't happen today or tomorrow, but it will happen.

    BTW.......I replaced the springs with lighter ones (by trial and error) on the tilting mechanism as mine were too hard to really tilt it in action.....even with a 150mm long handle.

    When you add the handle to your device I'd make it like the one in the pic I posted that has an air supply fitting incorporated...........you only have one air supply hole on your side of the device body and that is also where you want a handle to go.

    The CUTTERMASTER has the air supply fitting and a water removal filter device on the back side of the housing and a short 100mm long handle with a ball on the near side.
    Ian. .



  10. #90
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    Default Re: Weldon air spindle

    The Permatex takes 48 hours to fully cure so tomorrow might tell a tale.
    As you mentioned a few comments back, this is not rocket science. The differences between your Weldon and Cuttermaster evidence that. I'm blown away at having so much trouble getting it going.

    It will be a great pleasure to get to the point of deciding how I'm going to hold the cutters. I have ER40, 25, 16, and 11 collets, so a tight fitting chuck for any of them should work. 25 would work for 90% of the cutters I have, 40 would do them all but would require removing it from the Weldon shaft to clean the unit. Anyway, hoping for those decisions.
    Ozzie

    Last edited by ozzie34231; 03-28-2018 at 08:31 AM. Reason: expand


  11. #91
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    Default Re: Weldon air spindle

    Hi.....don't give up......if Duclos got one going then it'll happen eventually.........I feel in my water that it's something very simple.

    I was surprised to read previously that the bush is a press fit in the housing......and it leaked ....that's a puzzle.

    BTW....even without air on my spindle moves very smoothly through the bore almost like it's running on graphite or greased........with air it's feather light.

    If your spindle is "reluctant" to slide freely I'd investigate with a touch of blue to see if it's touching somewhere.....bush bore ovality comes to mind......by all accounts it should have .002" max clear and that would make it quite loose.

    A rule of thumb for a brass bush bore running clearance is .001" per inch of diam......for the spindle diam of 43mm approx", the .002"clear should allow it to rotate smoothly even without air.

    There could be some crud still coating the bush ID.....might need some lapping with wet and dry to clear it.

    I don't think a high polish is necessary as the spindle doesn't touch the bore.....but bore to spindle roundness would be more important.

    Model steam engine fanatics use a split wooden lap and grinding paste to hone their bronze and/or cast iron cylinders .
    Ian.



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    Default Re: Weldon air spindle

    On post #88 You'll see that I only have .001" at the most and some of my measurements show only .0003"
    The inside of the bushing looks pretty shiny. The shaft looks a bit weird. It's all shiny but the shine is not unidirectional, and as I've said there are inconsistencies in the diameter of about .0006".
    I'll try messing with some blueing to see if that will show me anything.

    Suppose the shaft is lumpy; lumps of a thou., but not across from each other, so no matter where I measure I'm never on two of them. They're small enough that the shaft fits in the bushing okay. But, when air tries to center the shaft, one or more of them presses hard against the bushing bore. Just a wild idea.

    If air doesn't escape around the outside of the bushing, that part of things is exactly like yours, Ian. So if things are sealed and I still get locking, I think the problem must somehow be with the shaft.
    My next experiment will be to get a small, bright light source to see if any light passes under the shaft laying on the granite plate. It's not as easy as it sounds. I have to get my eyes down near the plate and keep the light source from shining in my eyes. If I darken the room and point the light away from me and observe with a mirror I might learn a little. Or, I might not!

    Making an external lap from wood to cover several inches of length of the shaft might be interesting. I can't remember what grits of lapping grease I have, maybe 250, 500, and I think I bought a small quantity of something finer. And I have wet sanding paper of every grade up to 3000. I wonder if the paper inside such a lap would work?

    I just thought; I have a diamond coated sharpening block about 5 inches long.

    Ozzie



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    Default Re: Weldon air spindle

    Yes, you may be right.....consistency all along the bush bore to the spindle OD would be highly important as that is how the air does the all around separating bit......or so I think from many reads of air spindle design.

    If this model you have has been used without air due to it's design or otherwise.......perhaps there is some uneven wear.........mine moves smoothly, but with a slight drag without air, so I assume it is nigh on perfect in the bore spindle and clearance relationship......it may also have only been used with air all it's life.

    If you can source a cylinder hone that would be one way to true the bore .....a single high spot there could possibly throw a spanner in the works.

    Just for the info......the poor man's wood lap, which is easily made, is just a cylindrical wood bush, split down one side and a longish shaft with two tapered bushes each end........the bushes are progressively pulled together with a nut on the end......several of these are used with finer and finer grades of grit.

    If you're making a new bush then this is not required as you can bore round and true in the first place.

    Waiting to see the outcome of the sealant application.......if you still don't get joy I'd then lap the bore in situ......I think the spindle will be good enough if you can't see light under it.....a .0015" clear spot in the middle with a feeler gauge would be quite good.

    Something is puzzling me.........on the CUTTERMASTER the bush air exit holes are approx 40mm in from the ends.

    It would be logical to think that when the air emerges from these holes it would only have a short path to go before it exited to the outside from each end............possibly the pressure would also get to the centre part of the bush.....I don't know how.

    If/when I can get out to the garage today, I'll measure the end ID of the bush and the diam between the air holes to see if there is a difference in diams.

    Some time back I scored a complete 1/2" to 2" inside mike set at an auction, so that might be easier to use than the tele gauges.
    Ian.



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    Default Re: Weldon air spindle

    Quote Originally Posted by ozzie34231 View Post
    On post #88 You'll see that I only have .001" at the most and some of my measurements show only .0003"
    The inside of the bushing looks pretty shiny. The shaft looks a bit weird. It's all shiny but the shine is not unidirectional, and as I've said there are inconsistencies in the diameter of about .0006".
    I'll try messing with some blueing to see if that will show me anything.

    Suppose the shaft is lumpy; lumps of a thou., but not across from each other, so no matter where I measure I'm never on two of them. They're small enough that the shaft fits in the bushing okay. But, when air tries to center the shaft, one or more of them presses hard against the bushing bore. Just a wild idea.

    If air doesn't escape around the outside of the bushing, that part of things is exactly like yours, Ian. So if things are sealed and I still get locking, I think the problem must somehow be with the shaft.
    My next experiment will be to get a small, bright light source to see if any light passes under the shaft laying on the granite plate. It's not as easy as it sounds. I have to get my eyes down near the plate and keep the light source from shining in my eyes. If I darken the room and point the light away from me and observe with a mirror I might learn a little. Or, I might not!

    Making an external lap from wood to cover several inches of length of the shaft might be interesting. I can't remember what grits of lapping grease I have, maybe 250, 500, and I think I bought a small quantity of something finer. And I have wet sanding paper of every grade up to 3000. I wonder if the paper inside such a lap would work?

    I just thought; I have a diamond coated sharpening block about 5 inches long.

    Ozzie
    Hi, I wouldn't lap the OD of the shaft even if it is bent a thou or so as that would only make it smaller in the middle.and not correct the bend.....the lap would take off material all round the spindle......not the way to go.
    Ian.



  15. #95
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    Default Re: Weldon air spindle

    Well Ian, you would have lost the family jewels.
    No leaks, but no float.
    The unexplained symptom of increasing pressure causing increased difficulty turning still exists. It has lessened, but still there. I can still turn it at 80 lbs. The resistance is not constant, kind of sticky or lumpy, definitely not even along the length.

    I'm convinced the problem lies with the shaft and that the bushing is okay.
    I have not done any inspecting with a light and I'm not sure I'll get time today. (Until my wife's shoulder operation gets stronger I'm very much time constrained.)
    I will get to that and I'm hoping it will not show any bend but rather an unevenness that can be lapped away.
    If that is not the case maybe the best course would be to make a new shaft, maybe shorter, to see if I can get that to float. I think that the tube which is a prospect for being a new shaft is about 3 feet long so I could chop off a 10" hunk and still have enough for something more grand.

    When I get a working model I can decide where to go next; new bronze bushing, new full original length shaft, attempt to grind old shaft, whatever.

    In making a new shaft I should have a way to test it in the bushing and if not right, return it to the lathe or grinder for more work. That means working between centers I guess. The OD should be perfectly concentric with the ID. And the ID machined holes must be perfectly parallel to the finished shaft surface.

    Any ideas for a procedure Ian?

    Ozzie



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    Default Re: Weldon air spindle

    Hi, at this moment the ball's in your court.......you need to determine what you have and it's condition before any judgement can be made as to making new parts to fit old existing parts.

    That being said, once you test the spindle on the granite for irregularities you can decide what to do in that quarte, but I think that is not the real problem.

    If the bush is out of wack at all.......that is, oval or convoluted in any way due to previous wear and tear, it will need to be lapped out to make sure the shaft at least is moving smoothly even with a bit of friction from side contact but still smoothly.

    As I said, the one I have does move smoothly in and out and rotates without air on and I think that is the first criteria to achieve......even to the point of having up to .003" clear in the bush to the spindle.

    It's possible that there is a tight spot somewhere in the bush bore.

    I'm still puzzled as to why there was no air apparent on your model........it does have a patent no,......who would patent a plain spindle in a plain bush.

    I don't think the one I have would be smooth enough to use without air......but you never can tell.....perhaps the patent is the design of the complete device with tilt on the sub base.

    There is no way to tilt a cutter in a holding device on the Cincinnati cutter grinder.......the table ....as far as I know.....runs on balls and is moved with a wire drive........you grind the cutter by moving it back and forth on the finger......no tilt away after the in move.

    The Weldon device and the CUTTERMASTER both have a tilt away from the stone after the grind.

    Just as a matter of interest.......if you turned a simple bronze bush to run with a shaft it would indeed run smoothly if it had as little as .002" clear and that without any lube.

    I have a sneaking feeling that is where the problem lies.......unevenness in the bore......somewhere along the line the bush has become distorted.
    Ian.



  17. #97

    Default Re: Weldon air spindle

    Hey Ozzie! Congrats on scoring the Weldon air spindle! If the parts are corroded, you can try measuring the gap between the spindle and bushing diameters using calipers. To fix the air holes, redrill the housing, and for the bushing, try soaking it in rust remover or probing gently with a pin.

    The snug fit between the bushing and housing should prevent air leaks. The set screws secure everything in place. The tilting sub-base allows you to adjust the spindle's angle for different tasks.

    You got this, Ozzie! Happy machining!



  18. #98

    Default Re: Weldon air spindle

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