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  1. #61
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    Sep 2006
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    6463

    Re: Weldon air spindle

    Hi....on the line boring topic........I line bored a bearing housing for a tool post grinder build by mounting it against an angle plate bolted onto the crosslide in place of the compound slide.

    This would be the same for aligning a bush clamped against an angle plate as you can dial each end OD from the bar between centres.....this is the same method more or less I used for horizontal borer work.

    I don't think you need to go down that path........some more detective work needed.

    I would also dismiss the pressure closing the bore down as the iron is just too strong to be affected by as little as 30 to 80 PSI.

    To prevent the sealer I mentioned from getting into the holes, you could push the bush out 20mm each end alternatively and liberally coat it thereby not having to push the bush the whole way through.....this would leave the centre section of the bush OD clean..

    My observation on the unit I have is that the clearance between the spindle and the bush is so fine that the air pressure will be the bearing medium.......if the air leaks past the bush OD more I think the air pressure at the bush/spindle interface will drop big time......just a thought.

    As far as I can see, the spindle and bush bore surfaces need to be really highly polished to enable a close fit........even fine grinding is not good enough as under a 'scope the surface resembles a plowed field with jagged hills and valleys whereas a lapped surface is almost mirror finish.......not sure if that is absolutely necessary.
    Ian.

  2. #62
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    Jul 2004
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    442

    Re: Weldon air spindle

    Alright, suppose the air outside the bushing is high and the inside too low. That doesn't tell me why the spindle locks up. Yes maybe it won't float that way, but why/how the lock??
    I could seal the bushing on both ends with O-rings, but what does that do?
    I'm leaning to the idea that somehow pressure outside the bushing is distorting it in some way. I see no other logical explanation.

    As for finish, I think that may be important, but finish is not locking this spindle. I must find why the spindle locks under higher pressures, then I'll worry about getting it to float.

    In the Duclos article from years ago on making a floating spindle, he turns and bores with ordinary HSS tools, no finishing at all. And there are videos of those spindles working. I'll try to find a link and post it here.
    Ozzie

  3. #63
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    Jul 2004
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    442

    Re: Weldon air spindle

    Ian, so glad you're here because bouncing ideas to someone makes my brain work better. What I wrote in the last post got me thinking, "distorting". My bushing is not a press fit, it is a snug fit. What if the housing is not exactly round. The square inch area of the outside of the bushing is about 30. Thirty times the air pressure is quite a push, maybe not enough to shrink the bushing, but maybe enough to distort it if the housing is not perfectly round. That's what I'll look at next.

    Here is a link to one video showing the Duclos floating spindle. Watching him sharpen with an undressed wheel is a bit painful. But in the comments he links to his build and on page two, reply 33 there is a video of it floating.

    https://www.youtube.com/watch?v=H1Rxunxi5wI[/url]
    I think this is that link
    https://madmodder.net/index.php/topic,9283.0.html[/url]
    Ozzie

  4. #64
    Join Date
    Nov 2012
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    145
    Quote Originally Posted by handlewanker View Post
    Hi....on the line boring topic........I line bored a bearing housing for a tool post grinder build by mounting it against an angle plate bolted onto the crosslide in place of the compound slide.

    This would be the same for aligning a bush clamped against an angle plate as you can dial each end OD from the bar between centres.....this is the same method more or less I used for horizontal borer work.

    I don't think you need to go down that path........some more detective work needed.

    I would also dismiss the pressure closing the bore down as the iron is just too strong to be affected by as little as 30 to 80 PSI.

    To prevent the sealer I mentioned from getting into the holes, you could push the bush out 20mm each end alternatively and liberally coat it thereby not having to push the bush the whole way through.....this would leave the centre section of the bush OD clean..

    My observation on the unit I have is that the clearance between the spindle and the bush is so fine that the air pressure will be the bearing medium.......if the air leaks past the bush OD more I think the air pressure at the bush/spindle interface will drop big time......just a thought.

    As far as I can see, the spindle and bush bore surfaces need to be really highly polished to enable a close fit........even fine grinding is not good enough as under a 'scope the surface resembles a plowed field with jagged hills and valleys whereas a lapped surface is almost mirror finish.......not sure if that is absolutely necessary.
    Ian.
    Have a gander at this build by Doc at MadModders
    https://madmodder.net/index.php/topic,9283.0.html

  5. #65
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    Sep 2006
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    6463

    Re: Weldon air spindle

    Hi, just read the entire build by Doc...........the outcome is that the spindle and bush or housing are relatively simple items to make.....that is they are not rocket science in the fit of the bore and the spindle........a .002" clearance is well within anyone's capability if you work with machinery, and for parallel boring you can lap or hone the bore as required if you get some taper.

    Ozzie....I still think the "looseness" of the bush in the housing is your main problem........the home built ones in the build series seem to work as soon as the air was applied and were not hyper finished or hardened in any way, but they were directly in the housing without a bush..

    By that, if you seal the bush to the housing I'm thinking that you will have the same set-up as the Duclos one and the same one that Doc made......Doc bored a solid block of steel for the spindle to run in........ no bush etc.

    From the series of Doc's build, it appears he cut grooves in the housing bore and ran some holes into it from the outside for the air.........the Weldon has a groove or undercut in the middle of the bush bore.

    I would still make an attempt to seal the bush to the housing as a first option, even at the risk of clogging the holes.

    BTW.....if you do get this item to work (like mine) you'll be running a Rolls Royce instead of a Mini....it's that cool.
    Ian.

  6. #66
    Join Date
    Jul 2004
    Posts
    442

    Re: Weldon air spindle

    I've known about the Duclos unit long before I bought the Weldon, so when I saw a Weldon with an auxiliary base for little money, I figured the castings alone were worth the dollars. So, from the start I've thought I might need to make some new parts. Before doing that it makes sense to try getting the original parts to work. It never occurred to me that there was an early model Weldon that did not have a floating spindle.

    Right now I want to make sure that all the air that gets through the housing is able to get through the bushing. That way there should be no chance of air pressure deforming the bushing.

    Once that is achieved, sealing the ends of the bushing/housing joint makes sense. If I choose the right sealant, it will stop air loss and tend to keep the bushing from being deformed. I want to be able to push or press the bushing out.

    There should be no problem installing the sealant. If I put all but a half inch of the bushing into the housing, I can butter the remaining bit with the stuff, and on the other end butter the inside of the housing. The two sealants that come to mind are any of the gasket makers, and RTV sealant.
    Another option to sealing the ends would be to groove the bushing for O-rings.

    What are your thoughts on sealing the ends?
    Ozzie

  7. #67
    Join Date
    Nov 2012
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    145
    Quote Originally Posted by ozzie34231 View Post
    I've known about the Duclos unit long before I bought the Weldon, so when I saw a Weldon with an auxiliary base for little money, I figured the castings alone were worth the dollars. So, from the start I've thought I might need to make some new parts. Before doing that it makes sense to try getting the original parts to work. It never occurred to me that there was an early model Weldon that did not have a floating spindle.

    Right now I want to make sure that all the air that gets through the housing is able to get through the bushing. That way there should be no chance of air pressure deforming the bushing.

    Once that is achieved, sealing the ends of the bushing/housing joint makes sense. If I choose the right sealant, it will stop air loss and tend to keep the bushing from being deformed. I want to be able to push or press the bushing out.

    There should be no problem installing the sealant. If I put all but a half inch of the bushing into the housing, I can butter the remaining bit with the stuff, and on the other end butter the inside of the housing. The two sealants that come to mind are any of the gasket makers, and RTV sealant.
    Another option to sealing the ends would be to groove the bushing for O-rings.

    What are your thoughts on sealing the ends?
    Ozzie
    I thought the air system was not only to float the spindle but to also help stop any grinding dust from entering the bore.

  8. #68
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    Sep 2006
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    6463

    Re: Weldon air spindle

    Hi, sealant is the obvious way for first choice and the easiest........installing O rings is a bit more tricky.

    For O rings I'd groove the OD of the bush either side of the annular groove round the outside ensuring that the outside air hole in the housing can still meet the annular groove and penetrate into the inner undercut.

    A small amount of water in the housing will allow the O rings to slide through and it'll evaporate after a time.

    The grooves need to be a good finish on the sides and bottom and allow the O rings to be slightly proud of the OD of the bush as they need to be compressed when pushed into the housing......the compression makes the O rings tight against the groove sides, bottom and the housing bore otherwise the air will leak around the O ring.

    The O ring is a round section and the groove is a square section.....this will allow the O ring to deform almost to a square section and fill the groove.

    If this Weldon model you have is an earlier model and was not designed as an air spindle........i cannot imagine how useful it could be as there would be too much friction and it would have to be lubricated which immediately attracts the grinding dust and clags up the works......apart from wearing it out........perhaps that is why it was locked solid when you got it.

    If the very worst comes to the worst.......you could make a new bush out of bronze and put the air holes and grooves exactly where you want them........the bronze and steel mix would not seize up like steel on steel or iron would.

    I definitely would not touch the spindle as it would be difficult to make that item with it's surface finish and hardness as you have it.........but also leave the bore of the existing bush as is......providing the inside finish was not damaged from scoring by the spindle removal exercise.

    That rings an alarm bell in my mind...........if the inside of the bush DOES have score marks going longitudinally then maybe this is where the air is escaping.

    If it's badly scored then I think a new bush is on the cards.

    That would be relatively simple to make as it can be a very light press fit in the body with some sealant too, then honed to a close fit in situ to the spindle to give approx .05mm clear.....design for the grooves and holes to be established.
    Ian.. .

  9. #69
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    Sep 2006
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    6463

    Re: Weldon air spindle

    Quote Originally Posted by tom o View Post
    I thought the air system was not only to float the spindle but to also help stop any grinding dust from entering the bore.
    Hi, that would be a by product of the design as the escaping air would accomplish that without a seal that would cause friction.......the sole purpose of the air is for a friction free bearing.
    Ian.

  10. #70
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    Jul 2004
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    442

    Re: Weldon air spindle

    I spent only a few minutes on the Weldon today, busy solving probing problem on the mill.
    I did some measuring. The inside of the air nipple is about .265", so three 1/4" holes through the bushing are plenty. If my math is correct that passage is .055 sq in. The cross section of the exterior groove I cut in the bushing is only .013 sq in. I don't want to cut it much deeper, (there is the internal groove), so I'll make it about four times as wide.
    That should eliminate external pressure on the bushing. I'll see what that does and if the spindle still won't float I'll try to determine if a lot of air is escaping between the bushing and housing, and if so, go to a sealer. If that works I might do the O-rings.

    As for damage from the disassembly there is surprisingly little galling on either bushing or shaft; almost none on the bushing and some on the shaft. Evidently the corrosion was softer than the metal parts. However the pressure needed to break them apart was great enough to bend the shaft a little, I think. The shaft turns easily without air for the most part; the exception being if I move it longitudinally I can find a tight spot. I presume that is where it is bent.

    A hunk of brass or bronze big enough for a new bushing would break the bank, but I think the material doesn't matter much. If I can get the spindle to float at any place along its length, but binds at other places it will of course indicate need for a new spindle.

    Ozzie

  11. #71
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    Jul 2004
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    442

    Re: Weldon air spindle

    Actually I see some bronze bushing stock on Ebay the exact right size to make a new bush. $40. I won't bite now, I have both aluminum and steel stock that would be good. Tempting though.

  12. #72
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    Sep 2006
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    6463

    Re: Weldon air spindle

    Hmmmm....aluminium might do the trick....dissimilar metals etc, and it turns very easy.......also, it cost less than brass or bronze and experimenting won't break the bank.

    If you do go the aluminium way I'd turn the OD a light press fit and leave the bore slightly oversize, also add the exterior annular groove and holes.......ideally you want to finish the bore when it's pressed into the housing.......this is where a line boring exercise comes into play.......you also don't have to be dead blind concentric to the OD when you finish the bore to size.

    However, line boring is a fiddly exercise and if your lathe can turn without too much taper, I'd suggest mounting the whole housing on an angle plate on the face plate and just bore it as is......honing or lapping the bore will correct it anyway.

    As far as line boring is concerned, if you can mount it on the crosslide then it's a piece of cake thereafter.....you can bore it dead parallel and do a minimum of finishing with some wet and dry on a wooden stick.

    So, sealant first and see what happens.........O rings will be a bit more tricky.

    I've just discovered I have a disk with Photoshop 7 on it, bought some time ago that wouldn't load onto Win 7 but with Win 10 it went straight in, so now I'll dig out my files with the Weldon pics, downsize them and post them.

    The fact that you already have the housing and the sub base is 90% of the job.......getting it to work is now in view.

    I've been browsing the 'net to see what designs make an air bearing work and some have a series of small holes (1mm diam) around the bore and spaced along the bore length.......that means some exterior annular and cross grooves to link them all up.......design time etc.
    Ian..

  13. #73
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    Sep 2006
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    6463

    Re: Weldon air spindle

    OK....here's one pic of the Weldon air spindle to see how it downsized for the forum posting size.
    Ian.
    Attached Thumbnails Attached Thumbnails DSCF1624-A.jpg  

  14. #74
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    Sep 2006
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    6463

    Re: Weldon air spindle

    Hi....just collected a few more pics I have on file of another Weldon air spindle from a USA EBAY listing a couple of years ago..

    This one appears to have a number of smaller bushes and spindles that come in a tool box set.
    Ian.
    Attached Thumbnails Attached Thumbnails Weldo0n Sub Base-1.jpg   Weldo0n Sub Base-15.jpg   Weldo0n Sub Base-21.jpg   Weldo0n Sub Base-9.jpg  


  15. #75
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    Jul 2004
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    442

    Re: Weldon air spindle

    Pictures look same as mine.
    I didn't get out to my shop/garage yesterday, but I did get the seller of the piece of bronze to part with it for $31 including shipping!

    I've looked at dozens of pictures like yours with extra bushings standing near the main unit, but I never see any air passages ????

    Maybe I'll get something done today but there are several "Honey-do"s in the way; take Ginny to therapy, give the floor scrubber a workout, etc.
    Thanks for the pics Ian.
    Ozzie

  16. #76
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    Jul 2004
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    442

    Re: Weldon air spindle

    Specs on Bronze I bought.
    Bronze Cored Rod Round Stock Bushing Material 2.27" OD x 1.645" ID x 6-1/8" OAL

    The piece of steel tube I have is 1.750 OD so if I do both they are a good match
    The stock bushing is 2.125 OD and I think 1.683 is the ID

    Line boring on my lathe would be interesting but tedious as hell I think. I have a piece of 1" stock long enough to make the bar, and I'd need to make an indicator holder to measure the advance of the cutter. Setup, while not complicated would be fiddly.
    Anyway I'm confident I can bore in a chuck straight within .0002"; 1 inch boring bar, HSS bit.

    Hmmm; if one were getting a minuscule taper could it be eliminated via CNC. I think my lathe is not set up with a crazy big number of steps per inch, 20,000 ?, so that probably wouldn't work.
    Ozzie

  17. #77
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    Sep 2006
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    6463

    Re: Weldon air spindle

    KISS.....if you can bore fairly tight I'd lap or hone it to size after pressing in......much simpler that way......you might be able to get a cylinder hone as they use them for small whipper snipper and chainsaws petrol engines etc......but some wet and dry on a split lap also works..

    That piece of bronze was a gift at that price.....lucky you, the gods are smiling ....LOL.

    BTW....the first pic in post #74 shows the handle for tilting and the air pipe at right angle to it, so 2 birds with one stone.

    Have you decided on a hole/groove layout for the new bush?

    I think as you already have an air hole in the housing you would need to make an annular groove around the outside middle with through holes to the middle undercut as already is.....or do you want to go down the same path as the CUTTERMASTER design that has 3 holes in from each end?

    I think that would be the simplest way as all you'd need is 3 annular grooves in the bush OD.......1 each end 40mm in to match the 3 hole positions and a third one around the middle......no undercuts in the bore....... with a longitudinal cross groove to connect them together.

    The holes in the CUTTERMASTER are approx 8mm diam so no problem with them blocking up.
    Ian.

  18. #78
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    Jul 2004
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    442

    Re: Weldon air spindle

    It's almost 4pm here; only half the floors scrubbed and the old guy is tired. Taking a break that might turn into quitting for today.

    With all the air going to the middle, Weldon style, it's critical that both shaft and bushing be machined pretty accurately; not so difficult commercially but in a garage shop, tougher. How critical, I don't know. The Cuttermaster idea seems more bullet proof.

    If it comes to making a new bushing, probably will, I wonder if I should do a trial in aluminum or just try the bronze right off.
    The bronze I bought was a specific piece, but I found that he sells the same stuff by the inch at $4 an inch plus shipping. He originally wanted $24 for the piece and $20 shipping. I offered him $15 plus shipping with a note that shipping was too high and he could do better with USPS flat rate. He came back with a penny discount but $7 shipping. So I'm saying I can probably buy another piece at the same price.
    I have 2 1/4 solid round aluminum, I think.
    I need to look around Ebay to see what the AL is worth.
    Ozzie

  19. #79
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    Jul 2004
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    Re: Weldon air spindle

    The AL is worth half as much.

  20. #80
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    6463

    Re: Weldon air spindle

    Hi....the more I read on the 'net about different air spindle designs the more I realise that there isn't just one way to make it fly.....er, float.

    Some have a myriad of small holes all along the bore......that would be humungous to achieve.

    Reading the post by Doc on the Duclos design and I think it's a simple exercise no matter which way you get the air in..........but the consensus of opinions is that there must be a close fit to the spindle.........they talk of ..05mm (002") clearance.

    The commercial ones used in T&C grinders have hardened spindle etc as this will ensure that you won't burr the spindle by knocking it about as some operators tend to do with other people's tools.......a single ding on the spindle in the soft state and it'll jam in the bore and damage it......but for the dang thing to just work it doesn't have to be hardened at all.

    On the cost factor, aluminium would be the way to go as you can easily work it and as there is no actual contact it should last forever.

    It'll be tricky holding it for boring and turning as the wall will be quite thin and it's a long bush.
    Ian.

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