Mondiale Celtic 14 parts - Page 2
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  1. #21
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    The only proper way to do this is to have the gear hobbed
    If you do it single tooth the gear will be very noisy
    Check if you can find stock gear and shrink fit a ring on the turned down body
    Also I do not think it is M2.5
    That would with Z=115 give a OD of (115+2)x2.5=292.5mm
    That looks to big to me
    The best way to determen is measuring the centre to centre distance and the OD and # of teeth of both gears
    And now check if it is all to standard gear size You can use this formula
    OD= (#teeth+2)x Modul
    If the gear is corrected in some way you defenitivly have to get someone involved
    I also would expect the gear to be hardened and ground


    Peter

  2. #22
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    I called somebody here who maight have some spares for this machine
    The Celtic 14 comes in some models
    could you please post or PM a picture of your machine
    Also of the gear perhaps with some dimensions (in mm please)

    Peter

  3. #23
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    Thank you all for the responses. I know the best solution to do it right is to farm the gear out...but that rather defeats the purpose of having the hobby. Not to mention I have already been down for 2 months with this problem when the gear was shipped out the first time. I am almost done accumulating the tools, so I will at least make an attempt at the repair. Worst case I screw it up and have to farm it out later...nothing lost but time learning my machines better.

    It had been a while since I looked at the draft of the gear, so I mis-spoke about the details. It is 6.5" in diameter with 65 teeth. I think using your formulae, Peter, that puts it in module 2.5. The first cutter, a 2.5/#7, arrived and it looks like a very good match. I do assume the gear was originally hardened...but a previous repair was done in brass on about 8 of the teeth, and they still show the repair machine marks. So I know brass will suffice for my hobby use, at least. When I said I would toy with the idea of nylon and make a spare, that was with the expectation that the nylon would wear relatively fast. Of course since I am using a VFD, the gear outer teeth...used only for reduction...may never get used at all. I don't have any time on the machine to know it's characteristics yet.

    I may play with casting at some point, but right now I am not set-up for it. I also understand the "proper" way to cut a gear is a hobb...but I think simple cutters will work for my use. Noise and a reduced life are secondary concerns on a hobby lathe since it won't be working for a living like it used to in the shop it came from.

    I have looked through stock gears, but finally got overwhelmed. There are too many suppliers and no good search systems online. A couple calls left me feeling like a buffoon on the phone for even asking. If anyone knows a stock 2.5 module 65 tooth gear I would much prefer to use it as a repair. To me, the biggest challenges on this job will be the inner hole, which must slip on the spindle shaft. I do not have an internal grinder, so I will have to hone it to clearance. And then the inside dog teeth. I am not completely certain how these were machined...or how to go about repeating them. thus the best solution is likely to machine off the outside spur gears and press a new blank onto the old center gear.

    Again, thanks for the replies...I can use all the tips I can get. Will keep you posted as I work through the repair!

  4. #24
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    There is a 1.4mm difference in the formula
    The original is with 6.5" 1.5 mm smaller as should be with the formula
    That is a bit much to use a standard gear
    Please measure a bit more accuratly
    I can get a standard gear M2.5 Z=65 (OD167.5mm) for about €30,-

    But I think my contact has the original gear for you (see post 22)

    Peter

  5. #25
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    SS25/65B 2.5 mod 65 tooth Metric Pitch Spur Gear in Steel with Boss

    I thought you said 115 teeth? Now it is 65?
    Bill D

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    Quote Originally Posted by CJD View Post
    Again, thanks for the replies...I can use all the tips I can get. Will keep you posted as I work through the repair!
    Due for a dose of the obvious?

    There ain't a lot of POINT is doing one gear, the hard way, and probably rather badly, if-even the FIRST go works... when you aren't going into the BIZNESS of making MORE gears.

    May be a rare lathe in Texas. Wasn't SUPER common, even in Europe.

    But they surely made more than just the one.

    Pay attention to Peter in Holland. He's an experienced Machinery dealer. In EUROPE. Next DOOR to Belgium. Where the lathe was made. Bicycle distance, same day, actually, though it might be tiring?

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    OK, be nice....I work full time at a real job, am assembling a 4 axis CNC Bridgeport, renovating a house, and working this Celtic issue...including 3 other gears in the feed train that need to be cut...and I'm OLD. I have been working every angle for this for over 2 months and did not get to this point by choice. I have Called Mondial directly and they laughed at me for asking for parts on this old lathe.

    Peter, I am sending a PM.

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    Peter, I tried to send a PM, but it seems to go into a "stored in empty folder", and it will not let me access the folder. I don't think it is sending. Here are some pics of the machine and gear:











    The measurement I gave (6.49"/164.8mm) was made with the gear installed, using calipers, and half of it under the oil bath, so I think 1.4mm is within tolerance for those conditions. You can reach me at [email protected]

    Thanks again for your help!

  9. #29
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    I got your message and already replied
    The guy had a different gear
    To me it looks like a CI gear
    I ame a bit confused of what you need
    Is that one piece on the picture or 2 pieces
    If I cannot find a replacement I would buy a stock gear and turn a flange on the old gear and a innerflange on the stock gear and bolt it on
    Looking at the drawing that must be possible. I would not weld any of it

    Peter

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    Yes, the gear is all one piece. It is the main drive gear which is keyed to the spindle. A dog gear slides to engage the internal teeth for direct spindle drive. Then, with a second lever the counter gear slides to engage a pinion with the outer spur teeth for a reduction spindle drive.

    I agree that melding a new outer spur onto the original center would be the best option.

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    Do not weld it on
    Certainly not if its CI
    Bolt it on with a flange
    Peter

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    Quote Originally Posted by CJD View Post
    Yes, the gear is all one piece. It is the main drive gear which is keyed to the spindle. A dog gear slides to engage the internal teeth for direct spindle drive. Then, with a second lever the counter gear slides to engage a pinion with the outer spur teeth for a reduction spindle drive.

    I agree that melding a new outer spur onto the original center would be the best option.
    Simple grocery store arithmetic 101 economics, folks. A better way is to cheat.
    Arrange for either of direct drive only or geared drive only.

    IOW ELIMINATE the complexity, even the dog clutch.

    Provide for whichever ratio you used least-often by some other means, elsewhere in the drivetrain.

    Or do without. Or go and use a different lathe.

    A Mondiale Celtic is a decent lathe, but no more than that. A legend it was never.

    Can't save 'em all. Even when they ARE "legends".

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    Quote Originally Posted by thermite View Post
    Simple grocery store arithmetic 101 economics, folks. A better way is to cheat.
    Arrange for either of direct drive only or geared drive only.

    IOW ELIMINATE the complexity, even the dog clutch.

    Provide for whichever ratio you used least-often by some other means, elsewhere in the drivetrain.

    Or do without. Or go and use a different lathe.

    A Mondiale Celtic is a decent lathe, but no more than that. A legend it was never.

    Can't save 'em all. Even when they ARE "legends".
    I hear ya'! But, I just bought it and the 2k lb anchor is sitting in my garage. It costs $500+ just to haul the thing to the scrap yard, so I have to make a try at it before kissing it goodbye. So far I have only invested $50 in postage to Al Babin. It is currently operational in direct drive...and if I cannot get the gear repaired I will always have that. It's not time to give up on it yet.

    The only reason this thread is dragging on is I am waiting for the final mill cutting wheel for the gear. It was only 2 weeks ago Al finished trashing the gear and sent it back. I will have it repaired for the cost of the cutting wheel and $5 in scrap steel. If Peter can find an entire gear, then bonus!

  14. #34
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    Quote Originally Posted by CJD View Post
    I hear ya'! But, I just bought it and the 2k lb anchor is sitting in my garage. It costs $500+ just to haul the thing to the scrap yard, so I have to make a try at it before kissing it goodbye. So far I have only invested $50 in postage to Al Babin. It is currently operational in direct drive...and if I cannot get the gear repaired I will always have that. It's not time to give up on it yet.

    The only reason this thread is dragging on is I am waiting for the final mill cutting wheel for the gear. It was only 2 weeks ago Al finished trashing the gear and sent it back. I will have it repaired for the cost of the cutting wheel and $5 in scrap steel. If Peter can find an entire gear, then bonus!
    One of the very first macbine-tools I ever used was a shaper. I have a 12" Sheldon. Also a 7" K&T slotter.

    But there's blind-ended work to do on that part. TEDIOUS job at best. Very.

    I'd want material for three blanks, not just the one.
    Steel if I had to, Bronze if I could. CI NFW.

    Hint.. you are not likely to "get it right" first time out of the starting gate.

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    Bummer. Thanks for the link, Peter, but when I tried to order the 65 tooth gear is out of stock. That is pretty much my luck on this project so far. They do have the 16 tooth in stock, but I will wait to order that one until I have solved the "problem gear" issue.

    Therm...curious, what is CI? I have a partially working lathe and plenty of time to screw up till I get it right. I plan to get practice with gear cutting on the main selector gear, which is also worn to oblivion...a 1.5 module 22/24 tooth gear. Only when I am comfortable with the new mill will I dive into the big gear.

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    Quote Originally Posted by CJD View Post
    Therm...curious, what is CI?
    Cast Iron. Useful only when it IS "cast". To save money in high volume.

    For machining from the solid, if CI was the only material available for making a gear, I'd just go and use friction-rollers, roller-chain, or belts.

    Alloy steel as can be hardened it what you want.

    Deep, case-hardenable 8620 at the least. It can even be be welded. "Mostly", anyway. 4XXX has very nearly identical alloying composition and "goodness features" as ordnance steel, but is NOT as tolerant of welding. Mind, it can be DONE, but... PITA.

    Bronze costs more. A Helluva LOT more, but works well and you can actually repair a screw-up if you make one and/or solder-braze or furnace-braze complex bits together.

    Best is you chase-up an OEM gear from a part-out, next-best you chase the component ones Peter linked. If the website says out-of-stock, email them and inquire anyway.

    And THEN?

    Don't try to TiG bits together. Just drill, precision ream, pin them and gently "upset" the pins, riveting style. Soft Iron rivet stock will work a treat. Or even ignorant CRS. Cold Rolled Steel. Or Bronze pins.

    Or even shiney-wood rivet/pins. But I didn't say that. I wasn't even clocked-in the day that lie was told!

  18. #38
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    I made a rough drawing of how I would do it
    Turn a flange on the inside of the Z=65 M2.5 stock gear
    Then turn down the original gear so it fits the flanged gear and bolt it together
    Boltheads on the chuck side I think as there is room for them
    But you are in a better poition to determen that
    Important is that all is centered and parrallel to a couple of 0.01mm



    Peter

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    Quote Originally Posted by Peter from Holland View Post
    I made a rough drawing of how I would do it
    Turn a flange on the inside of the Z=65 M2.5 stock gear
    Then turn down the original gear so it fits the flanged gear and bolt it together
    Boltheads on the chuck side I think as there is room for them
    But you are in a better poition to determen that
    Important is that all is centered and parrallel to a couple of 0.01mm



    Peter
    That could work.

    I'd still use the rivet approach rather than threading and threaded fasteners.

    A spur gear has to carry the load on about one tooth and a half, average contact.

    Figure six rivets, plus their skin-friction, will be under only a tiny fraction of that "localized" stress.

    So even soft Copper, Brass, or Aluminium pins can work, loaded lightly, and nearly all of the load in shear.

    - No need to cut threads. Just holes with a slight chamfer, each end.

    - No need of protruding "heads", nor even fully-flush heads. A modest "upset" into the chamfer can even be BELOW "flush".

    - Fewer stress-risers in the parent metal.

    - Rivets are easily drilled-out if ever the need comes.

    Bronze age didn't end 'coz we ran out of Bronze.

    Rivets didn't cease working when threads were invented, nor TiG, either, one.

  20. #40
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    Like mentioned To me the old gear looks to be CI
    I do not like riveting that material
    It can work but I would not use mild steel rivets for sure
    And if there is space for boltheads What is the problem then
    And certainly Do Not Weld
    The gear he tries to order is C45 Do not weld that if there is no need
    Especially if you are a amateur

    Peter


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