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  1. #31
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    Quote Originally Posted by cba_melbourne View Post
    You have never aligned a headstock that required the torque shimming method, have you? There is no point before you have made this experience yourself.
    You made the statement that an alignment bar is required to align a headstock. I have stated that is crap. Several other people here who I know to have very extensive machining experience and who's opinions I respect enormously have said it's crap. You finished up admitting in your replies that it is crap. I respectfully suggest you accept that as fact and move on.

    Not everyone on this forum is rolling in money. I've been reading parts of the forum but not commenting, however when I saw this "advice" posted I was prompted to say something as I think it's completely disrespectful and quite wrong to cause somebody to spend their hard earned money on something that they're told is, and I quote, "really, absolutely, required" when it is in fact nothing more than convenient. They don't exactly give away MT5 test bars, and I would have to think very seriously before I bought one. No wait, I did, and I didn't! If anyone else has money to throw away on that type of thing then good luck to them. As Michael has said, they're handy for other things too, but again not required if money is really tight and it may mean sacrificing something else.

    On that note I'm outta here. As soon as I saw a name or two I basically knew how this was going to go, but I hope, if nothing else, it's caused some people to do their own investigations as to whether a test bar is "required" to align a headstock and then consider whether on that basis they really want to spend their money on one. I bought 400 kg worth of known grade steel off ebay that I enjoy working my way through and all for less than what they're asking for a Chinese MT3 test bar. I know which I'd rather have, other's milage may well be different.

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  3. #32
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    Quote Originally Posted by Pete F View Post
    .................
    On that note I'm outta here. ..................
    So you have never torque shimmed a headstock, have you?

    The OP has a low cost Chinese lathe with a headstock that wobbles on the bed. He needs good advise on how to best handle this. Not fantasy advise on how it would/could be handled on a 20 times more expensive lathe.

  4. #33
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    Quote Originally Posted by cba_melbourne View Post
    So you have never torque shimmed a headstock, have you?
    I was apprenticed into this caper at 17 year old, I'm now 51 years old. I'm in at about 34 years

    For the life of me , I cant't recall anything that was "torque shimmed"

    This hysteria you waffle on about the holy grail of head stock alignment, is frankly sick.

    This "Torque Shimming" you waffle on about, paper, shims doesn't exist in the real world. I take it you bought some really nasty Chinese .

    I'm in the Yellow page's. I get 4 to 6 inquiries a year to look into some sub par piece of equipment like that.
    Last edited by Big Shed; 11th July 2015 at 08:47 AM. Reason: Keep it family friendly please

  5. #34
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    I have a Hafpos AL340 with a rocking headstock, something I discovered when I needed to realign the headstock after a minor work jam a while back. Gaining enough knowledge to rectify that rocking at some time is one reason I took Phil Machtool’s scraping class last year, but I digress.


    I don’t have a test bar, I could have made a 2 collar bar, but even easier was to chuck a piece of bright round and use the theory of rotational averages to realign the headstock axis with the ways.


    I found that because headstock rocked the alignment moved when I tightened the hold down bolts. It became a matter learning how much to misalign the headstock so that it came true when the bolts were tightened. Don’t like it but it will have to do for the moment.


    Is this process (bodging) what is meant by the term torque shimming? Or is it something more?

  6. #35
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    Sadly continuing off topic for the moment, but -

    Shimming is the process of putting in material (nominally hard - as opposed to gaskets using soft stuff) between surfaces in a joint so that there is no gap. If alignment is changing because of the bolt torque it means the material filling the gap is the wrong thickness and/ or the mating surfaces are not 'flat'. In a properly assembled joint there should no movement when things are close to torque - and the torque on bolts is there to elastically stretch the bolts so that they increase the contact force between the two mating surfaces, hence increasing frictional forces.

    Using bolt torque to twist things away from a natural state is bad practice, as it stresses components un-necessarily (before anyone objects because they level with jacking bolts, they are used to put things back to a natural state - ie straight, flat). While some designs may call for this do be done, that should be a conscious decision on the part of the designer and not just to cover for poor component quality. If this is the case I would expect to see this acknowledged in the machine manual.

    Back to the OT -

    • Test bars can be used for aligning headstocks, but for the average hobbyist probably a purchase that may not get much use.
    • The purchase and use of one is a personal decision.
    • Other methods are available that can give similar results.
    • Some form of reference bar (that may be a test bar or may be something similar) is certainly advisable for helping to line things up.


    I don't think I've missed anything.

    Michael

  7. #36
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    Are there really lathes so poor in construction they shim the headstock from factory new......if I'm following correctly, yikes!!

  8. #37
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    Thanks for the advice and general discussion everyone. It was never meant ot be a discussion on headstock alignment, since I know this has been done to death here and other forums but it's difficult to offer alternatives to spending (or wasting) money without going into different methods. So thanks to PDW, RC, CBA, Bob, Machtool, Pete F, Electrosteam and Michael. Hope I didn't leave anyone out.

    I think the best course of action for me right now is to do nothing. I have all but been talked out of an alignment bar since I agree that I can better spend my $. I was being a bit lazy I suspect!

    In the near future I have a VFD conversion in sight for the lathe. The motor has been sitting on the bench for some time. The original motor has been making a terrible bearing noise for a while now too. I'll have to move the lathe out to gain access to the rear motor mount and when I do that I may as well look at the HS alignment. I know for a fact that the contact surface area between the HS and the bed is not as good as it could be. There are lots of air gaps between mating surfaces, I know this because when I removed it last time, I was surprised to see that the underneath of the HS is hollowed out leaving only 4 high spots at each corner where it bolts to the bed. Aligning the HS was indeed difficult as once it was aligned, tightening the bolts (even slightly snugging them all in turn) changed the position making it difficult to achieve an accurate alignment. This time, armed with some basic hand scraping knowledge I will scrape the bed (under the HS) flat and do the same with the HS. This will no doubt affect the vertical alignment of the spindle to the bed but once I have two flat surfaces, then I can work on the vertical alignment with further scraping of the HS underneath. There will still be a big hollow underneath but at least all the mating surfaces will be nice and flat with nothing moving when the bolts are tightened. It has been on my mind for a while and I was hoping to never take the HS off but I guess to get this thing aligned properly once and for all, I may as well do it properly. I have been happy with all other aspects of this lathe so why not spend some time on it.

    When I do take the HS off, I'll post some pics so people can see what a typical Chinese HS looks like underneath..

    Cheers,

    Simon
    Girl, I don't wanna know about your mild-mannered alter ego or anything like that." I mean, you tell me you're, uh, super-mega-ultra-lightning babe? That's all right with me. I'm good. I'm good.

  9. #38
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    Yes, headstock torque shimming is bodging. But the sad reality is, that nearly all these low cost hobbylathes ARE built like this. How else could you manufacture a 9" lathe for under $1000, or a fully featured 13" lathe for under $2000? Machtool, how much would you have to charge just for properly scraping-in the headstock on such a lathe? Do you expect Chinese factory workers to do the same job for free? You may turn up your nose at torque shimming, but the reality is that home shop users are buying these Chinese lathes and want to use them. They would all love to own something better. But they also must feed the wolf at the door, and the choice is either a cheap lathe or an old iron clapped out lathe or none at all.

    There is no point in waffling about the shortcomings of torque shimming. These machines have been around for 30 years and are here to stay, in very large and ever increasing numbers. Hercus and Myford and many others are out of business and will not come back - they were too expensive. Accept this, or stand accused of being unrealistic. To imply that one cannot drive a car if he cannot afford a Mercedes Benz is just plain wrong.

    These lathes are torque shimmed at the factory to Schlesinger standards. Despite this technique not being as rigid as the conventional alignment method, most Chinese bench lathes are accurate and will remain accurate for lifetime to the perfect satisfaction of their owners. A few may experience transport accidents, of for one reason or another the headstock needs be separated. The owners have a legitimate interest to know how to realign such lathe without going to a scraping course first. Scraping such lathes is like overcapitalising your home, you can do it if you fancy - but is it really worth the effort? If that is what one wants, better move up to an old iron machine to begin with.

  10. #39
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    Quote Originally Posted by cba_melbourne View Post
    The OP has a low cost Chinese lathe with a headstock that wobbles on the bed. He needs good advise on how to best handle this. Not fantasy advise on how it would/could be handled on a 20 times more expensive lathe.
    Wait a minute. You said in post #4 that you do not have a lathe test bar, but have been thinking of buying one. You then went on to say, incorrectly as it turns out, that you believe a lathe test bar is "really, absolutely, required" to align a headstock. So in other words given you don't have a test bar and incorrectly believe you need one, you have never aligned a headstock on ANY lathe in your life. Then you have the audacity to keep trying to discredit me!

    Yes I couldn't agree more, what's required to be posted on forums is GOOD advice. We all make mistakes and don't know everything (although some apparently think they do). I have plenty of tools in my workshop that I don't really need, but that's life. However one thing about this forum is that people come from all different backgrounds and financial positions. I think it's frankly irresponsible to tell somebody they "require" a specific tool when that's untrue. What could be little more than "beer money" for one person could represent a very significant purchase for another member here, and I can't sit by and let people be talked in to spending money they may have saved hard for by someone who clearly doesn't know what they're talking about.

    As far as "torque shimming" (an invented word more commonly known as "Bodging", "Hacking", or just plain "Crap work"), and yes you're quite right I haven't ever aligned a lathe or anything else for that matter that way. Mostly because, as Michael has pointed out, it is a bodge and not the correct way to align anything. An excellent way to crack an expensive headstock casting however, so I guess there's no expenses spared in dispensing "advice". The correct way is to shim a headstock you described using shims, and that is the way it's done in the factory, with different shims selected to obtain alignment. It's possible to use laminated/peelable/onion shims, however in my case I have a box full of shim stock of various thickness and when combined with a bit of a scrape, alignment can normally be done relatively quickly. Chances are however I'll use some other thin METAL I have lying around as a shim, and not some compressible material. The shim stock isn't cheap so I try to save that for when it's really needed (ok I really am a tight wad I confess). The hold down bolts are then torqued to the same value and a torque wrench would be of value here to make everything repeatable. You'll need to do this a number of times unless you're very lucky, and making sure everything is repeatable will help to stop chasing one's tail. At this point I'll have to confess that I've never used a torque wrench for this and just go by feel, but using one would be good practice.

    That's about the extent of my knowledge in the area, and I think Phil would be the guy I'd turn to for some good advice if more specific details were required.

  11. #40
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    Quote Originally Posted by simonl View Post
    I think the best course of action for me right now is to do nothing.
    That is what I would do... A piece of thompson bar in a four jaw is all you need, even better is a straight bar with centres both end, then ground between centres as you can use it for other alignment things like tailstocks.. This is where a good library of older books becomes invaluable...
    Light red, the colour of choice for the discerning man.

  12. #41
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    Quote Originally Posted by Hunch View Post
    Are there really lathes so poor in construction they shim the headstock from factory new......if I'm following correctly, yikes!!

    Sadly yes. Although it turns out the headstock is not solid shimmed but “torque shimmed”.


    I’ve not given this much thought before, but I guess from the lathe maker’s point of view there are 3 methods of mounting and aligning the HS.


    One is machining the underside of the headstock and the corresponding portion of the lathe bed so the mounting points are coplanar. Probably the most expensive of the 3 options as it requires a degree of quality control, stress relieved castings etc.


    Two is to machine everything close enough and then solid shim. It would be fairly time consuming to mount and demount the HS to get the shims right. Solid shimming to me would be acceptable if not ideal.


    Three is to machine everything close enough then spend a minute or two (its a production line, you would soon become very quick at it) tweaking the hold down bolts (AKA torque shimming) sufficiently to keep Mr Schlesinger happy. Cheap and very nasty.


    Method 3 is the one that wins of course. Why that should be is the subject of another discussion completely, but suffice to say the importers bear most of the responsibility.

  13. #42
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    Quote Originally Posted by bob ward View Post
    .........................

    Method 3 is the one that wins of course. Why that should be is the subject of another discussion completely, but suffice to say the importers bear most of the responsibility.
    I have to disagree.

    Importers only import what their customers want and buy. Else the importer goes fast out of business. Customers want cheap. Not value, not perfection, only plain cheap. Just fit for THEIR personal purpose. Buyers typically go to extraordinary lenghts to find the very cheapest offer of their chosen machine. How can one blame the dealers then???

    - Fact is, the vast majority of todays new manual lathe and new manual mill buyers are hobby users.

    - Fact is, the majority of todays hobby users buy a new lathe or mill. Only a smaller proportion chooses an old iron machine to recondition.

    - Fact is, the vast majority of todays hobby users choose a Chinese made lathe or mill (mainland China or less frequently Taiwanese) for well under $3k.

    - Fact is, only a very tiny minority of todays new manual lathe and mill buyers choose a well built and expensive machine like offered from Wabeco or Emco or Ceriani or the new South Bend range. In Australia, I would guess that accounts for maybe 10 units per year (not 10% of the market, I mean 10 units only) - not enough for any importer to make a living from. Ask yourself, how many owners of such new lathes are you aware of? Is there one at all? I personally do not know any. In the past, yes there were many Myford buyers - but not many since their prices crossed to $10K barrier - and Myford went broke.




    Quote Originally Posted by bob ward View Post
    .........................
    Two is to machine everything close enough and then solid shim. It would be fairly time consuming to mount and demount the HS to get the shims right. Solid shimming to me would be acceptable if not ideal...................
    I personally know of no example that would employ solid shims, like steel or brass strips. There is not enough "give" in solid shims to allow for more than about 2/100mm alignment. If shims are used, it appears to be either paper, or more often... just a mixture of paint and casting sand.

  14. #43
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    Quote Originally Posted by Pete F View Post
    Wait a minute. You said in post #4 that you do not have a lathe test bar, but have been thinking of buying one. You then went on to say, incorrectly as it turns out, that you believe a lathe test bar is "really, absolutely, required" to align a headstock. So in other words given you don't have a test bar and incorrectly believe you need one, you have never aligned a headstock on ANY lathe in your life. Then you have the audacity to keep trying to discredit me!
    Pete, I did it without a test bar. First I tried the RDM method but gave up on it. Then the good old spool method. It took me several days, the best part of a week. That is why I can say with confidence that if the lathe requires torque shimming, the only practical way to go about is to buy a real test bar.

    And no, I have no intention to discredit you or anyone else for that matter. You do that to yourself. I shall put my money to my mouth. Here is the deal: I buy a stock AL51G from machineryhouse. You use your test bar and spools and whatever to confirm its specs. If its less than the Schlesinger specs, we use those the machine shows. Then we take the headsock off, and you have 8 hours time at my place (I am just out of Melbourne, and you get coffee, the shop is heated) to realign it, using no test bar but just a level and your spools with an indicator. No scraping. It needs to meet Schlesinger specs or whatever specs we found before taking the headstock off. We check headstock parallel to the bed in both planes, and at tailstock height and the TS side offset marks roughly lining up. If you succeed, the lathe is yours to take. If you fail, the lathe is still yours but you owe me $1k (or whatever the lathe did cost me). Are you in?

  15. #44
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    Crickey! I just wanted to know about buying a test bar.... [emoji1]
    Girl, I don't wanna know about your mild-mannered alter ego or anything like that." I mean, you tell me you're, uh, super-mega-ultra-lightning babe? That's all right with me. I'm good. I'm good.

  16. #45
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    Best answer in my opinion is if you want it buy it if you use it great if not you still have it.

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