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Thursday, March 16, 2017

Machinist "Humor".... ( or Truth? ).. This is good.....

 I just received this from Leigh and it would be so nice to send this

back to MY customers on most of the quotes I have to do.

 Most of the bullet points are soooo true ! ....... enjoy:


Note here is the LINK to the original and here is the LINK to Mr Hoffman's page




This was written as a HUMOR piece. I assume no liability for any loss or damages if you're foolish enough to actually send it to a customer. If you lose all your business and starve to death, I don't want to hear about it. I hereby place this page in the public domain and you are free to copy any or all of it for whatever purpose you desire.

Dear Valued Customer,
We are responding to your RFQ for p/n ___________________, received on ___/___/___.

Please note the following issues with your print. Some of these may simply be money wasters, others are show stoppers:

  • Missing dimensions- If you don’t know, we can’t guess.
  • Conflicting dimensions or tolerances- Please choose wisely.
  • Confusing geometry- We see the lines but have no idea what the part is supposed to look like. Please add appropriate hidden lines, views and other clues as to what you want.
  • Fuzzy figures- Please provide electronic copies with sufficient resolution that all numbers and details are clear.
  • Tolerances too tight for proposed fabrication methods- If you don’t want to pay for grinding, lapping and honing, move the decimal over by one or more places. That would be to the right, in case you were wondering.
  • Tolerances too tight for any known fabrication method- Please allow your draftsperson/designer to see actual machine shop equipment and methods periodically.
  • Tolerances inappropriate for the material being used- Teflon flows and Nylon absorbs water. The parts will be right when they come off the machine, but we can’t predict what size they might be when you receive them. Actually we can predict; we predict they’ll be out of tolerance.
  • Part too large for available equipment- Yes; we know it fit on your computer screen when you drew it, but so would the Queen Mary. Even if you can steam the boat up our driveway, that doesn’t mean we have a machine big enough to work on it.
  • Part too small for available equipment- Yes; it looked easy when you drew it at 1000X scale. So do the parts in a ladies wristwatch. We are not watchmakers but can recommend both watchmakers and other shops that specialize in this sort of work. In either case they will lighten your wallet by remarkably disproportionate amounts as your parts shrink.
  • Length to diameter ratio impractical for the features desired- You may want to talk to someone with a Swiss screw machine or who can do center-less plunge grinding. Neither is an economical small quantity process.
  • Features in inaccessible areas- If we can’t get to it, we can’t machine it.
  • Sharp internal corners- There is no such thing as a perfectly sharp tool and thus, no perfectly sharp internal corners. You can however, be sharp enough to tell us what radius is acceptable, or if we need to machine an undercut.
  • Extreme surface finish requirements in areas where lapping and polishing processes can’t be applied.
  • Extremely thin or negative wall thicknesses- We charge the same amount for machining even if your part is gone when we’re done. We’ll probably also check this box if you have counter-bores that just start to break out or threads that deform or break into adjacent walls, making those nice parallel lines or slots.
  • Non-standard drilled holes- Please note the sizes of #1-60, A-Z and fractional size drill bits and use those sizes on your prints. Seriously, this one annoys the hell out of us.
  • Tiny/deep drilled holes and tapped holes- Check the size and L/D ratio of your holes. We don't like to remove broken drills and taps from parts and if the yield goes down you won't like to pay for it.
  • Tolerances too tight on thread depths/lengths- Allow two thread pitches of relief next to shoulders and don't over specify tapped thread depths. Go through or drill deep enough to allow some room for chips and so the use of spiral flutes and bottoming taps can be avoided. Or not. It's your our money!
  • Metric warning- In theory the ease and cost of a metric part should be identical to an imperial part. Because we’ve spent decades accumulating expensive inch-based tooling, the reality is somewhat different. We usually end up buying special metric sizes and the price of the parts will reflect this.
  • Odd thread warning- Machinery’s Handbook lists many hundreds of standard threads but no, you decided you simply had to invent a new one. OK, you're not the first and won't be the last. We can cut almost any thread, but expect higher prices if we have to buy special taps, inserts or gages.
  • Customer supplied stock too small- There isn't enough material to clean up the surfaces and remain within tolerances. We tried squeezing the stock in the long dimension, hoping the middle would get bigger, but it didn't work. Please supply the next larger stock size.
  • Customer supplied stock too large- The chips are piling up a lot faster than the parts. We're going to make a lot of money at the scrap yard. Not only did you pay too much for the stock, rest assured you'll pay more for your parts due to the longer cycle time.
  • Customer supplied stock is rubbish- You get what you pay for and inexpensive, often imported, aluminum and other metals frequently don't meet machinability standards. We're sure it's metal of some sort, but have little interest in trying to machine it. Please stick with name brands of known composition.
  • Material is unobtainable- Just because you found it listed in some table on the Internet doesn’t mean you can buy less than a railroad car full, or that the mill will be making it anytime in this decade.
  • Special heat treatment or cold working is unobtainable- No, it isn’t really unobtainable, but the delivery time is two orders of magnitude beyond your expectation for the finished parts, as is the cost.
One of the following actions will apply:
  • A quotation has been supplied as we believe the above issues will be easily resolved with little impact on the price.
  • We are responding with a NO-BID because we simply aren’t set up to efficiently do this type of part or the quantities requested.
  • No quotation will be supplied but we do invite you to resubmit the RFQ with the above items addressed and we’ll be happy to reload our guns and take another shot at it.
We’ve tried to respond with some typical snarky machinist humor to get your attention and keep your day interesting. If we’ve gone so far as to check any of the boxes below it suggests you may want to examine your business relationships and maybe adjust your expectations as to what a machine shop requires to make a part and what we can and can’t supply, while still making enough profit to remain in business.
  • An astonishingly high quotation has been supplied as we believe the above issues will be resolved only with much confusion, many wasted hours and bad feelings had by all parties. Extra margin has also been included to cover the inevitable rework and replacement parts we expect you to demand, resulting from unclear drawings and limited access to the people who can actually answer our questions and approve changes.
  • We are responding with a NO-BID because we do not believe the above issues can be successfully resolved prior to hell freezing over.
  • We are responding with a NO-BID because the desired delivery time occurs either in the past, a few hours from now, or suggests that you have no clue about material lead times and what it takes to make the part.
  • We are responding with a NO-BID because you have consistently wasted our time quoting parts that you obviously have no intention of ordering.
  • We are responding with a NO-BID because you haven’t paid for your previous orders and don’t appear to have any intention of doing so.
  • We are responding with a NO-BID because we have made this part before, or a very similar one, and our entire workforce has threatened to quit if we ever have to make it again.
  • We are responding with the name of one of our most respected competitors, with our highest recommendations, in hopes that they will get suckered into this money losing disaster, while we work on parts that will at least allow us to break even.
Thank you,
Your friendly local machine shop


  1. The worst application of machining I ever encountered was not due to the machinist, but to the person requesting the pin.

    We were changing the hydraulic cylinder on a large machine. The design had a six inch pin, which didn't rotate, held a bearing, which rotated internally, and the entire mess was placed in a housing very difficult to access.

    The tolerance on the pin was in thousands below the housing bore. Since the pin might be removed only once every ten years, or so, all the lubrication in the world wouldn't stay on the pin, and there were no grease channels, or zerts for lubrication.

    We had to cut the pin away, the new pin was identical to the first, and required a 12 pound sledge to pound into position.

    If someone had consulted a machinist, lowered the tolerances, added some grease channels, and bored for grease fittings, someone in the future would find a three day job could be completed in one day, or less. Nobody did, so I have sympathy for the next crew that changes the cylinder.

    1. On quick example that I see allll the time. Small threaded holes, M2, M3, 2-56, 4-40 called out "thru" and the is a 3/4 inch plate or thicker. Who needs that much thread?

      Also.. out of laziness, every dimension is 3 place.. +/- .005. They don't want to change the CAD settings.

  2. When I have a customer say "HOW MUCH!," I show them this and then the door. (I have hanging in my office.):

    "It 's unwise to pay too much, but it's unwise to pay too little, too.
    When you pay too much, you lose a little money...that is all.
    When you pay too little, you sometimes lose everything because the thing
    you bought was incapable of doing the thing it was bought to do. The Common
    Law of business balance prohibits paying a little and getting a lot...it
    can't be done. If you deal with the lowest bidder, it is well to add something
    for the risk you run, and if you do that, you will have enough to pay for
    something better."

  3. My first job was a welding shop. We had one engineering firm we did wirk for all the time and we had a policy that if the bid came from a specific engineer we added 20% to the bid.


  4. Heh, looks like something that was sent to a couple of my scientists!!! :-)

  5. .047 hole .120 max deep, 00-80 thread .110 deep minimum, cut tap only. I might actually use that form.



    The designer bent across his board,
    Wonderful things in his head were stored,
    And he said as he rubbed his throbbing bean,
    "How can I make this thing hard to machine?
    If this part here were only straight,
    I'm sure the thing would work first rate.
    But would be so easy to turn and bore,
    It never would make the machinist sore.
    I better put a right angle there,
    Then watch them babies tear their hair.
    And I'll put the holes that hold the cap,
    Way down here where they're hard to tap.
    Now this piece won't work, I'll bet a buck,
    For it can't be held in a shoe or chuck,
    It can't be drilled or it can't be ground,"
    In fact, the design is exceedingly sound. He look again and cried, "At last!
    Success is mine, it can't even be cast."

  7. years ago I worked with an Industrial Engineer who had sat down at a drawing table and bacged out a drawing for a part and sent it down the pike. later that day he was notified that his parts were in, that they were a bit small, but within spec.

    He had forgotten to change the title block and the sheet he picked up had tolerances that reduced his part to literally nothing. They made him sign for a bag of air, while they laughed at him.

  8. I'm not in that same field, but I could write a similar screed for the construction industry. Oh wait! I did!
    Fortunately I didn't send it to anyone.

  9. As a mechanical designer (and CAD jockey), I've learned a lot from machinists. You just have to ask them.

  10. I routinely bid more than the job will take, but not much more. Doing so relieves the mystery in a couple of areas. One, it relieves the customer of sticker shock when the part is actually done, and if the customer balks at the price, it is usually because he wants to change our cost structure to his favor, and/or he probably doesn't have the budget to do what he wants anyway.

    A story (ongoing and true): Customer brings us a 300+ pound control arm, and talked about us reaming it to get the two ears lined up (There are four sets of ears). I told him at the outset we do not have reamers that size. He said other shops do, so I told him he should go to them. Then when the job is done (under bid) he said he expected it have the two bores lined up within .001 of an inch perpendicular with a surface. Before I heard this requirement we had been going round and round with him adding requirements and saying things such as "Don't you remember me say this..."

    He kept hammering on the theme that I should mount this monster on a Bridgeport and machine the desired surface. By this time I was tired of listening to his bullshit. I told him we had a devil of a time mounting the control arm just to do the bores, and we had neither the machine envelope, nor the stroke to do what he wanted. Not could we line up a 3 inch more sufficiently enough to ensure his new requirement. He said other shops do (They do, but he would have to go to someone who had a boring mill and machine it to that requirement, but would have to do that from the outset, not a coupla thousand bucks in), so that's when I clammed up.

    Gawd knows where this is going to end up. We overran the bid, but we haven't (and probably won't) charge him for the additional time. I decided the second time he tried to run his con on me I'm too old to be stressed out it.

    Thanks for reading.

  11. Pure classic, Irish....Thanks!

  12. I'm running into this "invent new threads" all the time now. I 3D print professionally, and the people who bring me STL files have clearly never read a copy of Machinist's Handbook.

    Disclaimer: I am not a machinist, I never will be, but I have worked with many and listened to them when they explain stuff. If you listen and at least make an attempt to follow the advice given, projects go a lot quicker and they will try to accommodate the occasional "rush-NEED NAO" demand.


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