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Thread: Keyway question ???

  1. #61
    dstryr is online now Titanium
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    Quote Originally Posted by Dave Cross View Post
    I agree with the "if it was drawn on center it should have been made on center" crowd. Who eyeballs stuff in a machine shop anyways? That is for plumbers and construction workers.
    X2. If it didn't matter why didn't he put the key way through a hole if it truly didn't matter? LOL ASS-U-ME.

  2. #62
    jdj
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    Quote Originally Posted by SND View Post
    Nothing untrue about it gears are gears, the vast majority of them have a key for driving purpose and generally doesn't matter one bit where the key is(and decent mass produced gears I've seen seemed to have them all in the same spot, probably nature of the process eh?). Sure some custom gears will be a bit more picky for some applications.
    Now in the rest of the things made in the world, keys have many more applications than just driving shit, but no I can't show any drawings... hell half the keys I cut are there exactly for location purpose in relation to everything else on the part, for stuff that will never spin.
    Can't base what goes on in one fairly closed/dedicated industry as being standard for the rest..

    I machine impellers all the time (of various kinds) where the keyway and bolt circle's relation don't matter at all. Just like you are describing a gear. It drives it. That is a COMMON purpose of keys and keyways! TRUE, NOT THE ONLY PURPOSE! But it is COMMON that they drive shit. You certainly do not have to show any drawings! THIS is common sense. THEREFORE, gears and their keyways are NOT some FREAK OF MACHINING where nothing is similar in physics involving them. Wanna make the point that it isn't ALL the same in all parts involving keyways? FINE! NO DOUBT! But there are similarities in use and orientation of keyways in other parts.

  3. #63
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    When a key is stated to be central......... does it mean centrally located, or centered in the bore......... or both ?? If the key is called out to be central, yet gives no tolerance..........then what ??? Just some more theoretical questions.

    Also.........I have NEVER made a key yet that was on a part that DIDN'T spin. What kind of work do you guys do anyway ???

    Maybe my interpretation of the print has something to do with the industries I normally serve. I have a gear making background. I turn spindles, and idler gears and stub gears all the time. Keyways and internal splines are common everyday items that virtually NEVER need to be in relation to anything else, unless called out. I guess that's the part of this discussion that everybody seems to miss. Finding a keyway that needs to be in relationship to a bolt circle in my business, is like trying to find a needle in a haystack. It isn't common at all.



    Frank
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  4. #64
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    Quote Originally Posted by Dave Cross View Post
    I agree with the "if it was drawn on center it should have been made on center" crowd. Who eyeballs stuff in a machine shop anyways? That is for plumbers and construction workers.
    You've never done high volume production or screw machine work have you ??? I've done more than my fair share of low tech, low money military production runs that are just that, eyeballed. In fact, I questioned the practice with my customer and was told, "this ain't rocket science, get 'er close and drill the hole, it doesn't mean shit".......... while I'm standing in his facility discussing these parts with him, he has parts falling off the overloaded parts chute on his screw machine. He picks up a shovel and literally shovels the parts, chips, floor dry and all into the finished parts tub about 2 feet away and goes on about his business. I couldn't believe my eyes. There are all kinds of work out there.......and some of it isn't pretty.



    Frank
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  5. #65
    IndGild is offline Cast Iron
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    How hard is just to go over it. You made mistake, period.

  6. #66
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    Quote Originally Posted by rockfish View Post

    Maybe my interpretation of the print has something to do with the industries I normally serve. I have a gear making background. I turn spindles, and idler gears and stub gears all the time. Keyways and internal splines are common everyday items that virtually NEVER need to be in relation to anything else, unless called out. I guess that's the part of this discussion that everybody seems to miss. Finding a keyway that needs to be in relationship to a bolt circle in my business, is like trying to find a needle in a haystack. It isn't common at all.

    Frank
    Two very common applications of precisely locating a keyway or spline to everything else are timing gears/sprockets and driveline components(slip yokes/end yokes, etc.).


    The only time I have ever seen timing components not keyed was on a diesel Volvo/VW engine where the camshaft had a tapered end and you had to line up the cam by locating a lobe and then tighten up the sprocket.

  7. #67
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    Quote Originally Posted by alphonso View Post
    Two very common applications of precisely locating a keyway or spline to everything else are timing gears/sprockets and driveline components(slip yokes/end yokes, etc.).


    The only time I have ever seen timing components not keyed was on a diesel Volvo/VW engine where the camshaft had a tapered end and you had to line up the cam by locating a lobe and then tighten up the sprocket.
    You may have missed my post where I said that I've done hundreds, if not thousands of parts where the keyway location was of no importance and if it was, it was spelled out clearly on the print that the location must be held to other features. Just because your experience is different than mine, does not make my experience any less relevant. This is the first example I've come across......EVER, where I was burned on this issue, in 29 years of machining, working in aerospace, a gear shop, machine tool builder and now running my own shop with many different customers in different fields. Every single print that needed the keyway tied to another feature, was spelled out clearly on the print........ not just lined up with the center line. All of the prints were drawn that way, but assumed that the keyway location was of no importance. So...... given my experience over the years, why would I believe that it would be done any differently ??? Why would I believe that I've made a mistake, when all other prints for all of my other customers accept that the radial location of a keyway is not important, unless otherwise specified........even if drawn on centerline ??? Not to mention the fact, that my vendor ALSO agrees with me. Now........it seems like the entire board here thinks I'm a hack, but that's OK, because I know better.

    Anyway........ it's a done deal. Parts are being made over. The customer never even received the parts in the first place, because I called on it BEFORE I sent them, and they aren't late. The customer will be happy. I'll be out the price of the parts..........and I'll get to wait forever to get paid for them. Another lesson learned.




    Frank
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  8. #68
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    That's like if someone brings you a part that gets a 30*deg bevel on it for a weld prep.

    Do you just get it close with a protractor or machine graduations?


    Or do you get a sine bar/ plate and make it 30*deg, 0'minutes, 0" seconds???

    If you use space shuttle tolerances for everything, you'll lose your a$$ is the kind of work that Frank, me, and several others do.

    In these types of shops if it is important/critical, you better say so, or have it on the print.

    All of the CAD drawings usually have the keyway at 0*, 90*, 180*, or 270*.

    If someone brings in a simple keyway job that isn't critical, and you make a fixture and gauges, and get it within the millionths, you can't charge them $2500 for a simple 1/2" keyway that should be about $35.

    I am not picking on the others here. There are times that you make the gauges and goodies for a perfectly timed part.

    It is good that you have the ability [knowldege] to do that, because many don't.

    It reminds me of the time we were doing weld test tubes for the Natural Gas Co.

    There were some kind of angle 47*???????

    I set up a compound and beveled tool and started ripping.

    My parts were 6 or 7 an hour.

    There was one guy that set-up a taper attachment, and was taking 45 minutes per part, and had a 2 hour set-up time.

    In this case it didn't matter.

    Some of my customers would allow me (if there is enough room on the part), to re-drill the holes, and if possible fill in the old holes with all-thread and TIG weld the tops. Then smooth out or face in the lathe.


    JAckal

  9. #69
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    This video is the easiest explanation I've found so far that deals with this issue. Clearly Frank is not the only one that runs into this. This pretty much spells out the current rules. (I've posted this in Franks other thread on the same topic as well)

    Simultaneous Requirements
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  10. #70
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    Quote Originally Posted by rockfish View Post
    You may have missed my post where I said that I've done hundreds, if not thousands of parts where the keyway location was of no importance and if it was, it was spelled out clearly on the print that the location must be held to other features. Just because your experience is different than mine, does not make my experience any less relevant.
    Not trying to bust your chops at all. Just pointing out to the general audience that there are a few very common instances where keyway location is critical. And, yes, I have been bit by the location question more than once.

  11. #71
    SND
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    Thing to really remember here is when it comes to customers, there are no standards, nothing you've done for anyone else in the past matters. Each one is different and you have to learn how each operate and their expectations and when in doubt always ask. I don't have 2 places that send me the same type of drawing, sometimes a scratch on a part isn't a big deal, and for others its a huge deal.
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  12. #72
    jdj
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    Quote Originally Posted by SND View Post
    Thing to really remember here is when it comes to customers, there are no standards, Each one is different and you have to learn how each operate and their expectations and when in doubt always ask. I don't have 2 places that send me the same type of drawing, sometimes a scratch on a part isn't a big deal, and for others its a huge deal.

    No question about THAT. I was NOT trying to argue (in previous posts) that people SHOULD assume all kinds of things about part drawings, simply that there ARE sane reasons WHY someone MIGHT.

  13. #73
    Dave Cross is offline Stainless
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    Quote Originally Posted by rockfish View Post
    You've never done high volume production or screw machine work have you ??? I've done more than my fair share of low tech, low money military production runs that are just that, eyeballed. In fact, I questioned the practice with my customer and was told, "this ain't rocket science, get 'er close and drill the hole, it doesn't mean shit".......... while I'm standing in his facility discussing these parts with him, he has parts falling off the overloaded parts chute on his screw machine. He picks up a shovel and literally shovels the parts, chips, floor dry and all into the finished parts tub about 2 feet away and goes on about his business. I couldn't believe my eyes. There are all kinds of work out there.......and some of it isn't pretty.
    Frank
    Actually all I do is production work. If the keyway feature didn't have its own tolerance you should have used the drawings' general tolerance, and if that left you with questions you should have made a call to your customer to get your facts straight. The part should look like the drawing.

  14. #74
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    Quote Originally Posted by rockfish View Post
    You may have missed my post where I said that I've done hundreds, if not thousands of parts where the keyway location was of no importance and if it was, it was spelled out clearly on the print that the location must be held to other features. Just because your experience is different than mine, does not make my experience any less relevant. This is the first example I've come across......EVER, where I was burned on this issue, in 29 years of machining, working in aerospace, a gear shop, machine tool builder and now running my own shop with many different customers in different fields. Every single print that needed the keyway tied to another feature, was spelled out clearly on the print........ not just lined up with the center line. All of the prints were drawn that way, but assumed that the keyway location was of no importance. So...... given my experience over the years, why would I believe that it would be done any differently ??? Why would I believe that I've made a mistake, when all other prints for all of my other customers accept that the radial location of a keyway is not important, unless otherwise specified........even if drawn on centerline ??? Not to mention the fact, that my vendor ALSO agrees with me. Now........it seems like the entire board here thinks I'm a hack, but that's OK, because I know better.

    Anyway........ it's a done deal. Parts are being made over. The customer never even received the parts in the first place, because I called on it BEFORE I sent them, and they aren't late. The customer will be happy. I'll be out the price of the parts..........and I'll get to wait forever to get paid for them. Another lesson learned.
    Frank
    I agree with Frank that the keyway was not specifically tied to the holes per the drawing. Many times inspectors will expect the parts to 'look' like the drawing even when the print does not state required angular orientation. Gear teeth to keyway orientation is very hard to visually see whereas bolt holes to keyway is easy to see it does not 'look' like the print.

    I get that Frank is remaking the parts. However, do the 'discrepant' parts really affect function at all except not looking like the print? Without showing the parts to the end customer, this is impossible to answer.

    GD&T is used to help convey the engineer's intent of acceptable condition of the part in regard to fit, form and function. This overrides the inspector's desire to reject the parts because they do not simply look like the print when the keyway to bolt hole orientation doesn't mean a damn thing.
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  15. #75
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    Actually............. I may not have to remake them over again. Their controller promised me a check the week of the 6th of this month. I sent them an e-mail asking about my check and I was told it was sent Tuesday. Still haven't received it. Today, I'll be receiving a Monday morning update request on their work, and they will be told that until I'm paid up full........every single job I have of theirs will be put on the back burner, while paying customers go to the front of the line. I'm not playing games any more.



    Frank
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  16. #76
    Dave K is offline Diamond
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    Oooh!! Scary move, but necessary at times. Let us know how that works out for ya. I've considered this tactic many times due to slow payers.
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  17. #77
    SND
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    When there's other faster paying work to do sometimes there's just no choice, prioritize.

  18. #78
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    I have been scanning the GD&T symbols online and I cannot find the one I am searching for yet. I am looking for a regular GD&T angle symbol < with a slashed line through it \. It basically means 'angle unimportant' (to datum -C- for example) This is a symbol in the feature control frame instead of a text notation like the video Gordon posted.

    I am now thinking the symbol is something we created in our internal GD&T specifications many moons ago for gears and the like. Gear teeth need to be accurately spaced to themselves as do the broached or hobbed spline features, but rarely do they need to be timed together on our parts.

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