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  1. #1
    Join Date
    Jul 2006
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    Melbourne
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    Default Worn thread on a saw spindle

    I am entering unfamiliar territory when it comes to metal work but hope that I can get a answer here. The threaded shaft on my table saw has about 30mm of thread on it, the thread at the start of the shaft has worn and I cannot do up the nut, making my saw a very elaborate boat anchor at the moment. There is approximately 5-6 mm of worn threard as best I can tell by eye.

    I have searched the forum and all the threads (no pun intended) have seemed to refer to damaged threads on a nut, not the bolt. I am hoping that someone can suggest how I can fix this without too much fuss.

    My first thoughts are along the lines of running the correct size die over the damaged area but have no idea how to work out what sort of thread it actually is. Can someone also give me an idea how to determine the pitch of the thread?

  2. #2
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    Nov 2008
    Location
    Sydney
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    Quote Originally Posted by Ray153 View Post
    I am entering unfamiliar territory when it comes to metal work but hope that I can get a answer here. The threaded shaft on my table saw has about 30mm of thread on it, the thread at the start of the shaft has worn and I cannot do up the nut, making my saw a very elaborate boat anchor at the moment. There is approximately 5-6 mm of worn threard as best I can tell by eye.

    I have searched the forum and all the threads (no pun intended) have seemed to refer to damaged threads on a nut, not the bolt. I am hoping that someone can suggest how I can fix this without too much fuss.

    My first thoughts are along the lines of running the correct size die over the damaged area but have no idea how to work out what sort of thread it actually is. Can someone also give me an idea how to determine the pitch of the thread?
    You don't say what is the diameter of the shaft; whether it is imperial or metric. Thread pitch is normally measured by using a set of thread gauges, which look a bit like a set of feeler gauges with one serrated edge. They come in imperial or metric. Imperial threads are measured as threads per inch (TPI), metric are measured by thread pitch in mm. You may be able to repair your spindle using a die nut rather than a threading die once you have determined the size. There is also a tool called a thread file, but they are not that common & require experience to use.

  3. #3
    Join Date
    Oct 2008
    Location
    blackburn vic
    Posts
    297

    Default Worn thread

    Hi Ray
    You dont say what make of saw you have so a general statement will be if it is of asian origin it will almost certainly be a metric thread and if it is from UK or USA it will probably be imperial thread.
    You can get a set of thread guages from your local machinery supply shop that will tell you what pitch that the thread is.
    As a roughy you can measure the thread pitch with a ruler but sometimes the difference can be very subtle to the casual eye. I am in Blackburn if that is of any use.

    Roger

  4. #4
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    Minbun, FNQ, Australia
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    Default

    Take your spindle nut into one of the big Nut & Bolt suppliers & ask them to work out what it is & then see if the have a Die Nut the same size.

    A Die Nut will clean up a damaged thread but it won't replace any metal that has been worn off it.
    Cliff.
    ...if all you have is a hammer, everything looks like a nail...

  5. #5
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    Aug 2008
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    near Rockhampton
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    I believe their are three options depending on what the saw spindle looks like..

    1. A new spindle.
    2. Rebuild the damaged thread with weld and recut the thread.
    3. Turn the damaged thread to a smaller diameter and rethread it and make a new nut to suit.

    I could fix it for you but I am too far away..I have repaired quite a few items with a similar problem, and it is not hard to do..

  6. #6
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    Feb 2003
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    Garvoc VIC AUSTRALIA
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    I'd be inclined to run a thread file over the start of the damaged thread then run a die nut along the whole lot.
    Regards, Bob Thomas

    www.wombatsawmill.com

  7. #7
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    Quote Originally Posted by echnidna View Post
    I'd be inclined to run a thread file over the start of the damaged thread then run a die nut along the whole lot.
    Hi echidna,

    I think a lot of table saw spindles are a square shouldered thread, I just had a quick look at mine and I think it's acme profile, which complicates things a bit. I wouldn't use a thread file on it, and large acme dies are pretty pricey, might even be more than the cost of a new spindle.

    So Ray123, can you look at the thread and see if it's a square shouldered profile? as that will have an impact on what the best repair might be.

    Regards
    Ray

    PS, Forgot to mention, on my table saw it's left handed! I wonder what a 1" x ? left-handed acme die would cost?......

  8. #8
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    Aug 2008
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    Charlestown NSW
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    Quote Originally Posted by RayG View Post
    PS, Forgot to mention, on my table saw it's left handed! I wonder what a 1" x ? left-handed acme die would cost?......
    How many spare arms and legs do you have? LOL.

    Spindle thread could be a non std size as well. I've seen that sort of thing before where the pitch has been very fine for the diameter.

    bollie7

  9. #9
    Join Date
    Apr 2009
    Location
    Marsden, QLD
    Posts
    93

    Default

    Quote Originally Posted by Ray153 View Post
    I am entering unfamiliar territory when it comes to metal work but hope that I can get a answer here. The threaded shaft on my table saw has about 30mm of thread on it, the thread at the start of the shaft has worn and I cannot do up the nut, making my saw a very elaborate boat anchor at the moment. There is approximately 5-6 mm of worn threard as best I can tell by eye.

    I have searched the forum and all the threads (no pun intended) have seemed to refer to damaged threads on a nut, not the bolt. I am hoping that someone can suggest how I can fix this without too much fuss.

    My first thoughts are along the lines of running the correct size die over the damaged area but have no idea how to work out what sort of thread it actually is. Can someone also give me an idea how to determine the pitch of the thread?

    If you can get the shaft out, make it real easy on yourself, take it to an engineering workshop, ask the boss, how many stubbies will it cost to fix.

    A carton of their favorite beverage, sure goes a bloody long way and it's generally cheaper than the hourly rate.

    This way, you dont have to worry about what thread it is and buy a die nut, lot's easier just buying a carton.


    regards radish

  10. #10
    Join Date
    Jul 2006
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    Melbourne
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    Default Thanks all

    Thanks for all the replies and advice. They have certainly increased my metalwork knowledge tenfold.

    The saw is a Carbatec model TSC-10HB and am fairly sure they are of Asian manufacture. It is a left hand thread but I am fairly certain the thread has sharp ridges, not square shouldered threads. (well, the worn area now has square shoulders)

    What is the difference between a die nut and a threading nut?

    On the face of it, I think trying a die nut sounds like the best option so far depending on costs, I am not keen on the welding/cut new threads option, I am not sure how easy it will be taking out the spindle will be and I definately don't want to go down the path of grinding off the existing thread/re-tap as that then complicates the matter slightly of having to get it to a precise diametre and using a bushing for the blade and would pretty much rule out using a dado set up on the saw I suspect.

    EDIT - it is as suspected by wiser heads than mine a acme thread and the spindle is shorter than I had pictured it in my head while typing. A new spindle or expert repair is starting to look the better option now

    I can get the nut on the spindle about 2-3 turns before it hits the worn area so if I can clean up that area, there is enough pristine thread past that to safely snug the nut home to the blade I believe.
    Last edited by Ray153; 23rd Jun 2009 at 09:51 PM. Reason: Went and had a better look at it...

  11. #11
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    Feb 2007
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    Katherine ,Northern Territory
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    Die nuts are usually hex shaped on the outside diameter and are not split through .
    they are used to rehabilitate threads that have been damaged by over tightening (stretching) or have dings on them that prevent the nut from screwing on

    A threading die is split so it can be adjusted to cut the thread smaller or larger.

    kev.
    "Outside of a dog a book is man's best friend ,inside a dog it's too dark to read"
    Groucho Marx

  12. #12
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    Oct 2006
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    Tallahassee FL USA
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    Re-threading the entire shaft will likely remove more metal than necessary, and compromise its fastening capability. If you can start the nut, and it jams part way along, you need only remove the offending metal. A thread file would be best for this, but for 60-degree thread forms, a small triangular file will suffice; probably why the 60-degree form was chosen originally anyway. For other thread forms, a flat file (possibly with a "dome" on the other side) should also work. In either case, remove only enough metal to enable further passage of the nut.

    Thread forms allow some liberty to still assure adequate clamping. As low as about 60% engagement has been found adequate in most cases.

    The left-hand threads don't matter, as far as finishing is concerned. They're typically used so that the fastening tightens itself.

    Cheers,
    Joe
    Of course truth is stranger than fiction.
    Fiction has to make sense. - Mark Twain

  13. #13
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    Apr 2009
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    Marsden, QLD
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    Default

    Go find out what the thread is, once identified, then go find out what a die nut will cost.

    Make sure your seated, when your being told the price of the Left Hand die nut.

    Think you'll find the carton of - "urine"- is still the easiest option.

    regards radish

  14. #14
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    Default Thanks again all

    I have looked at the parts list for my saw and made enquiries with CT, it looks like removing the spindle is reasonably straightforward, I am leaning towards replacing the whole thing as opposed to repairing the damage. More for the peace of mind than anything. Of course this is all dependent on the cost of a replacement spindle vs cost of repairs.

    I certainly appreciate the time taken to help educate a complete metalworking novice, now my knowledge level has been raised slightly, prior to this I was lucky I knew how to straighten a bent nail as I hammered it in.....

  15. #15
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    Quote Originally Posted by Ray153 View Post
    ....prior to this I was lucky I knew how to straighten a bent nail as I hammered it in.....
    Try a straight nail. They are easier to hammer in. Just kidding.

    Nev

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