chips stuck inside spindle taper during tool change
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  1. #1
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    Default chips stuck inside spindle taper during tool change

    I just got a huge reprimand.

    So when the machine is doing a tool change, a chip somehow made its way into the spindle, and of course this caused the tool to stick out ever so slightly. Problem is, my boss does his engraving with a center cutting chamfer tool. It requires very minute precision, meaning if the tool stuck out even more than .005" the engraving will be ruined resulting in a scrapped part.

    Problem is as I was changing part I failed to notice that a chip has somehow made its way into the spindle and caused the tool to stick out .005" more than it should be, and so now the engraving looks terrible. Between so many things you have to notice, having to work fast, etc. there are just so many ways stuff can go wrong in ways you don't even know could go wrong.

    So about 8 pieces got ruined simply because I didn't know a chip was inside the spindle bore when it did a tool change.

    Boss is someone who strives for perfection and even a 1% failure rate (10 defect out of 1000 parts) is unacceptable for him. But at the same time he requires things to be done very quickly with little to no time to inspect thousands of parts that you see every day. The machine is old and require lots of attention to details you never knew existed or else something could creep up on you (such as the machine has very poor chip handling facilities meaning if you didn't pay attention you could have a pile of chips clogging the machine).

    So I guess how can I prevent this from ever happening again?

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    Short of running your finger inside the taper before inserting a tool and/or cleaning the taper on the tool holder, there's not much one can do. Of course don't blow/wash the machine out without a tool in the spindle and don't lay tool holders in chips.

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    very doubtful I can run my finger in the spindle before every tool change, it has a 20 tool ATC.

    It's just those small random stuff that I fail to notice (engravings are very hard to see when there's a puddle of cutting oil on it).

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    Get your boss to install a tool-length gauge with automatic offset adjustment. That way, if a tool is inserted and is incorrect due to a chip in the taper, the offset would be changed before operations start to account for that.

    Alternatively, it could be set up to alarm and stop the machine if it doesn't match the originally set offset (with a clean taper). This is better, as tools should not be run with compromised mates between holder and spindle.

    If I were you, I'd also be looking for other job opportunities...

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    From what you said it sounds like the only time you need wipe tool\spindle is the engraving tool. We had parts on an older Kitamura, same issue and the only way to ensure a clean taper is like plastikdreams said, wipe both clean each cycle. Throw a M00 in there or roll the dice.

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    Yea, don't think he wants to spend the extra 3000 dollars for that. I told him they have tool offset setters on ebay for 40 dollars and you can program Mach 4 or whatever to do a tool offset every tool change.

    Except he doesn't use Mach 4 and just outputs G codes from Mastercam X5 and the machine uses Fanuc controller.

    How do you insert a "check offset after each tool change" command into it?

    And since the machine doesn't have a tool setter, the machine has no way of knowing where the stock is, or whether or not the tool offset is correct. I guess he felt for the cost of the parts, amount of time needed to make them, etc. that a tool offset setter isn't necessary... It would make cycle time much longer for one thing.

    How do I edit a program on the machine? Do I use MDI or EDIT button? Maybe I should sneak a M00 in the program while the boss is away so I can check the chamfer tool... would be more trouble but would ensure no scrapped part.

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    Edit button, if it has a M01 at the tool change make it M00.

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    I hope I have a next time though...

    Not sure if I should do this though as this would definitely make the operation MUCH longer and more tedious, but it would also guarantee that I'd never have a repeat of this again (or some other freak could happen like dropping the tool holder by accident).

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    QT: [So about 8 pieces got ruined simply because]
    Why 8 pieces and not one or two? Is that what you have to work on are you hopping around from one machine to another or do you have time between parts?

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    I was hopping between two machines, but more importantly, I didn't notice the engravings, and when I measured the part nothing was out of spec (which would have clued me in that something wasnt right) apart from the engravings. So I had failed to notice it until the boss did.

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    It then sounds like perhaps the work demand is strict. If not being fired then your error is not so bad.

    Likely you have to show grief for a time to be forgiven and the next flub by some other person will take the burden off your back.

    Hopefully, you learned a lesson that should have been in your instruction briefing.

    Note when you become the boss make a crew sheet for each job having all the instructions for each job.

    This is needed because in a low-skill environment the instructor can't tell all the important things with not having a crew sheet to go by. Low-skill is not a dig on you it just means that you did not invent the process for this job/work.

    The outcome of not having the crew sheet is that is every new worker is likely to make the same mistake.

    I have just seen the same at the deer blind company. I made a crew sheet for each job and the partner/owner does not brief a new guy with looking at the sheet..very often a new guy will make the very same mistake as a new guy of the past. Often because doing something might seem logical. faster or easier.

    The crew sheet might/should include the past mistakes so the new worker can be fore warned.

    On your job, that warning would be" watch for error after a tool change. But with automatic tool changing if done in process, one can't know a chip is in the spindle.

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    Quote Originally Posted by taiwanluthiers View Post
    I was hopping between two machines, but more importantly, I didn't notice the engravings, and when I measured the part nothing was out of spec (which would have clued me in that something wasnt right) apart from the engravings. So I had failed to notice it until the boss did.
    You indicated it making 8 parts bad.
    So the tool change happens, and then 8 parts get made with no further tool change ?

    I would be "at the machine" for that first part, when the tool changes, to verify
    it running right.

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    Quote Originally Posted by michiganbuck View Post
    QT: [So about 8 pieces got ruined simply because]
    Why 8 pieces and not one or two? Is that what you have to work on are you hopping around from one machine to another or do you have time between parts?
    I had the same question. An inspection is not just using gauges to make sure things are in spec, it needs to be visual as well looking for changes in surface finish, burrs, edgebreaks, and so on. On a manually loaded machine, the visual steps should get done at each part change even if the dimensional check are only every xx parts.

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    8 parts are made all with tool changes but for some reason only the engraving is bad.

    Part is motorcycle brake handles.

    Basically only dimension I was told to measure is the thickness where it mounts to the bike, because it affects the action of the handle. I'm given a reference dimension and told a tolerance. On those 8 parts the tolerance was within spec except for the engraving (meaning the part is good but due to bad engraving isn't in a sellable condition).

    I think what happened is the chip stuck onto the tool holder holding the chamfer tool, and only that tool. So that was literally the only tool causing problems.

    I'm told to check for stuff like rough finish, burrs, etc. but this is verbal instruction in very informal setting. In Taiwan they never ever have orientation or written "employees handbook". Everything is said to you once and if you forget they reprimand you like you are worthless. It is the way things are done in Taiwan. I don't like it but I can't change a society either. In the US everything is written down so as long as I study up on the handbooks and written procedure I'm fine... though to be fair when I worked at Walmart written rules are completely disregarded (they have CBL's and you spend 3 workday looking at a bunch of training programs then told by your supervisors to disregard them completely).

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    And if the workload is so fast jumping between machines then the shop inspector or the boss needs to perform the inspection of the first part/s.

    Everything is said to you once and if you forget they reprimand you like you are worthless.

    Every/most new guy feels that way and then matures to learn what to watch out for and to be more careful.

    Here in the USA one normally is not abused long because he will walk or get fired.

    I worked at a major shop where a mild-mannered guy was being brow beat by his boss for years..finally, the guy picked up a transmission slip yoke casting and broke the boss's skull into a number ao pieces. That boss lived but never came back to work. I can't remember what happened to the guy, everyone in the department stuck up for him and told how he was being abused.

    *No, I'm not suggesting you/anyone doing that, never get mad and beat someone up at work.

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    Yea he does. First of every part (he makes me do this too) your finger is on the stop button, and as the tool change happens and is lowered onto the stock to do work, you press the stop button just as the tool is at its ready position (or just before, there's a brief pause when this happens). You look at the position and look at the tool. You verify that it actually jives (that means if Z says 10, then your tool should be approximately 10mm off of the top of the stock). This is done for every single tool change in the first part. This is to make sure you didn't crash the machine, because you are making sure the tool offset is correct. Engraving and chamfer is the last tool before part is finished. The boss does this intentionally because it allows you to see the cycle is almost complete (it is always assigned as tool #10) but also because he uses that tool for engraving, and it requires extreme precision. Basically he said to feel the part where the engraving goes to make sure it actually did engrave (it takes a couple of tries to get the depth just right), but BEFORE you remove the part from the vise.

    I guess that's one good thing about Taiwan, they very rarely fire you. They reprimand you like hell almost daily. In the US they fire you as soon as you mess up, and they often do this without any warning.

    What I messed up on is failing to notice the engraving was off... because part has already been proofed and tested. It's just that a chip got onto the tool holder and stuck throwing the offset off. And it can happen randomly.

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    Quote Originally Posted by taiwanluthiers View Post
    Yea he does. First of every part (he makes me do this too) your finger is on the stop button, and as the tool change happens and is lowered onto the stock to do work, you press the stop button just as the tool is at its ready position (or just before, there's a brief pause when this happens). You look at the position and look at the tool. You verify that it actually jives (that means if Z says 10, then your tool should be approximately 10mm off of the top of the stock). This is done for every single tool change in the first part. This is to make sure you didn't crash the machine, because you are making sure the tool offset is correct. Engraving and chamfer is the last tool before part is finished. The boss does this intentionally because it allows you to see the cycle is almost complete (it is always assigned as tool #10) but also because he uses that tool for engraving, and it requires extreme precision. Basically he said to feel the part where the engraving goes to make sure it actually did engrave (it takes a couple of tries to get the depth just right), but BEFORE you remove the part from the vise.

    I guess that's one good thing about Taiwan, they very rarely fire you. They reprimand you like hell almost daily. In the US they fire you as soon as you mess up, and they often do this without any warning.

    What I messed up on is failing to notice the engraving was off... because part has already been proofed and tested. It's just that a chip got onto the tool holder and stuck throwing the offset off. And it can happen randomly.
    With that, it seems you were wrong and you did not check with due caution. You might need a .020 shim to feel the tool height to the part if not able to see +- .005 as needed.

    You should not lose any sleep over 8 such parts. but do show you due grief for a time, if that is expected of you..

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    Sounds to me like you are likely using an umbrella tool changer that is inside the cutting enclosure.

    Tell your boss if he wants to run production to buy real production machines. I honestly can't remember ever having a chip get into the taper of one of my machines

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    One of the machine is a Bridgeport GX710

    gx710.jpg

    ATC is similar to any of those Haas VMC, is vertical and has a separate enclosure. Taper is protected at all time except during the brief period the tool is swapped. Boss said to be mindful of it because sometimes chips gets onto the coolant nozzle then the vibration of a tool change would cause a chip to stick to a taper causing issues... I guess that's why some machines have automatic tool setter... the computer would know if something isn't right.

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    Increase the spindle air blast then.....the air blast is working right?

    Checking the taper is insanity. Why even bother having a tool changer?....might as well just hand load everything. Also the tool offset and part would be the last thing I was concerned about. Despite the taper being hard chips can still jack it up.

    If it is from chips falling out of the coolant nozzles then maybe it's time to plug the nozzles on the tool changer side of the spindle.

    IMO this is a machine and or process problem, not labor. Tool length probing is just a band-aid to avoid fixing the actual problem.


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