Broken change gear shaft on a grizzly 4003g lathe

Discussion in 'Machine Modifications' started by Ed, Dec 28, 2017.

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  1. Dec 28, 2017 #1

    Ed

    Ed

    Ed

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    The thread change gear turned the key 1/4 turn on the shaft.Need new shaft and new 40 tooth gear. Problem can't get shaft out of lathe gear case.Out side is a flange with a roller bearing between the flange and shaft. Inside case is 2 large gears pressed and keyed to shaft.Bearing seams to be seized to shaft and flange. Need to remove cover from shaft to push shaft into case to be removed from inside case.How do I unstick the bearing from shaft and case.Tried driving shaft back into case don't move, tried to drive flange off shaft does not move.Any help please. Thanks Ed
     
  2. Dec 29, 2017 #2

    Blogwitch

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    Go to this page and download the parts list.

    http://www.grizzly.com/products/12-...03G?utm_campaign=zPage&utm_source=grizzly.com

    I have no idea what your piece part looks like from the description, yours is just about the same same lathe as mine but different supplier.

    By looking at the assembly diagrams, it should give you a clue as to what is hidden and then maybe you can work it out yourself how to get it disassembled.

    John
     
  3. Dec 29, 2017 #3

    Wizard69

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    Bearings are commonly press fit onto shafts if not that a tight sliding fit. It might take a bit to force the shaft through the bearing. However dont use force until you understand how the shaft is assembled.
     
  4. Dec 29, 2017 #4

    Ed

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    Sorry for not putting in all the info. I have the manual on page 87 the shaft is part # 152 the end with the key # 157 is inside the case with 2 gears pressed on shaft. Hope this helps.
     
  5. Dec 30, 2017 #5

    Cogsy

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    Bearings are normally either a tight or press fit into/onto the rotating part and a slip fit into/onto the stationary part. So a rotating hub will have a tight fitting bearing and slip fit on the shaft, whereas a rotating shaft will be the opposite. It's likely in your case that the bearing is pressed onto the shaft.
     
    Last edited: Dec 30, 2017
  6. Jan 4, 2018 #6

    Ed

    Ed

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    I put my broken shaft on you tube.

    [ame]https://www.youtube.com/watch?v=ShmVK5slkoM&feature=youtu.be[/ame]

    Just need to highlight this and put in search box in you tube.
     
  7. Feb 21, 2018 #7

    Ed

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    Grizzly just sent me a card saying they can't get the gear and have no idea when or ever if the gear will come.I have all the other parts need gear to run lathe.. Need help on making a gear or buying a gear.
     
  8. Feb 21, 2018 #8

    GLCarlson

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    Amazon lists change gears from Boston Gear. This one looks like 40t (oops, you said that) probably 14.5 angle, 16 pitch (if it's not metric). About 40 bucks. Given Amazon's return policy, I'd just order what looked like the right one (ie, take a chance on both pressure angle and pitch) if you can't measure it/match to a picture/get the spec from Grizzly.

    https://www.amazon.com/Boston-Gear-...8396&sr=8-1&keywords=40+16+change+gear+boston

    Or try Motion Industries, Grainger, etc if there's one nearby.

    Unless this is a really odd size, should be no problem to source used or new. Change gears like this are common as dirt. Grizzly's response is appalling, though.
     
  9. Feb 21, 2018 #9

    Mechanicboy

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    The Grizzly lathe is a SIEG product, then the change gears is Module 1 and 20 degree angle.

    Easy to find the gear is module 1 --> Measure top of diameter of the gear: 74 mm top diameter in the 72 teeth gearwheel. --> (Z +2) x Module = top diameter in millimetre.
     
  10. Feb 21, 2018 #10

    V22

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    I’m curious to know if this is correct. I have the same lathe albeit with the designation AL960b and it’s made in Taiwan. As far as I know, all Sieg gear is made in China. I have seen references to to g4003 being made in Taiwan. It makes me wonder if Sieg have their own Chinese copy of this lathe?
     
  11. Feb 21, 2018 #11

    Mechanicboy

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    Construction is near same both taiwanese and chinese lathe and manual too..
     
  12. Feb 22, 2018 #12

    V22

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    Taiwanese is a level above Chinese. A significant difference at this level of lathe. An example at the higher end is the Taiwanese hlv-h copies. Beautiful quality.
     
  13. Feb 22, 2018 #13

    dalem9

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    Ed Bring me your gear
    and I will see what I can do .
     
  14. Feb 22, 2018 #14

    Mechanicboy

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    I has Sieg C6 lathe since 2005, nothing to be unsatisfied or worry about the quality. It had give me a lot of hours of use the lathe without trouble with the work.
     
  15. Feb 23, 2018 #15

    Ed

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    Thanks Dale. I'm going to try to clean up the teeth on the gear today. There is none missing or broken just a little ruff. The gear is metric, the one on Boston gear is English and has a 3/16 key where this one has a.5 mm key.Dale I've had the bug for 6 weeks and am now just getting over it. I don't want to give you any thing.I'll let you know soon hope it's gown away. Thanks every one for the help. There may be a problem getting things from China I see some tool selling places are now saying there cheaper tools are on back order.Sorry for the rambling must be a sign of getting better. Ed
     
    dalem9 likes this.
  16. Feb 24, 2018 #16

    Ed

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    worked on gear with file and some of the other gears in drive train. Put back together every thing turns smooth by hand until I engage the threading shaft then every thing gets hard to turn, With gears disconcerted the threading shaft needs to be turned with big channel locks.( the shaft is the long threaded shaft on the front of the lathe ). Does that turn hard or is it to turn easy?How do you loosen it up?. This may have been my problem that broke things.
     
  17. Feb 24, 2018 #17

    RM-MN

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    That threading shaft should turn easily. Check the bearing on the tailstock end, probably by removing it. (part 907) That part should slide off the shaft easily. Now try turning the threading shaft. If it still turns hard, keep looking for a bearing that is binding or something in the saddle that is contacting it that shouldn't.
     
  18. Feb 24, 2018 #18

    GLCarlson

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    Little Machine Shop sells a set of change gears, metric module 1, which includes 2(!) 40 tooth gears. For 35 bucks the set.

    Looks as if the OP is going to try to clean up his original gear. If that fails, this is a pretty easy way to get a new one. Could probably turn around and sell the rest of the set for what you paid, too.
     
  19. Feb 24, 2018 #19

    BillH

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    I “highly” doubt the 4003g is a Sieg product.
     
  20. Feb 25, 2018 #20

    Mechanicboy

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    You did read this in #11? "Originally Posted by Mechanicboy View Post
    Construction is near same both taiwanese and chinese lathe and manual too.."

    These is mostly copies of products both from Taiwan and China for competition in sales and quality.
     

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