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  1. rhmeng

    Vibration Specification - Correct Way to Complete Analysis

    So the structure is a product that we design that will essentially go on a rocket. The PSD curves are for a flight environment. We are not given requirements on how to run the FEA (ie 1X + 0.3Y, etc). I do not see how our structure could be free from coupled vibration modes. When analyzing the...
  2. rhmeng

    Vibration Specification - Correct Way to Complete Analysis

    We receive PSD curves for our vibration specification requirements. The curves are given for each axis (X,Y,Z). I have always set up a linear dynamic study for each axis (one study for X, one for Y and one for Z) and ran a study for each axis. I then look at the stress for each axis to make sure...
  3. rhmeng

    13/16-32 UN vs 13/16-UNEF thread callout

    I am designing a part with a 13/16 thread. I originally called out 13/16-32 UN 2B. The mating part was difficult to assemble because of geometry and was hard to engage because the thread size was so fine, and any small foreign object debri would make it bind. I decided to change the thread to...
  4. rhmeng

    Drawing color standard for dimensions?

    Hi everyone, thanks for all the comments. @drawoh you make a good point about not everyone having color printers.. thanks again
  5. rhmeng

    Tolerances for a Force Fit on a profile

    hey guys, thanks for the response. I believe there is a formula for surface pressure in the machinerys handbook, although it was for steel on steel.. I am not sure I know how to go from surface pressure to deformation. Or is it simply figuring out how much surface pressure that I want, then...
  6. rhmeng

    Drawing color standard for dimensions?

    Is there a standard for the color of dimensions on drawings? I have always used black for my dimensions, but recently we have been looking at using blue dimensions. I was curious if there is a standard practice for this, nothing in Y14.5 2009 that I could find.
  7. rhmeng

    Tolerances for a Force Fit on a profile

    I have a part that is made of steel that I want to press fit into a part that is made of anodized aluminum. The shape of the press is shown in the attached image and the dimensions are roughly 0.5" x 1.5". My question is on how to tolerance each part. Should I simply use the machinery's handbook...
  8. rhmeng

    tolerance pin, diamond pin

    JNieman, thanks for the detailed response, these will not be made in high quantities, probably only 3 or 4 at a time. They also do not have to be interchangeable and we can have matched pairs of mating parts. We should be able to work with the mfgr to tell them this. I came up with...
  9. rhmeng

    tolerance pin, diamond pin

    I dont really want a load applied to it, each part is housing optics, and they will be assembled and disassembled many times during the build. I think I get what you are saying tho, if there is a slight interference you will just have to push harder to mate the two parts, and it will deform...
  10. rhmeng

    tolerance pin, diamond pin

    actually real quick, to control perpendicularity it seems like the tolerances would have to be super tight for this to work. If Datum B hole is at a minimum .1772 + .0006 = .1778, and Datum B pin is at a maximum .1772 + .0005 = .1777, then the perpendicularity has to be controlled to a a tenth...
  11. rhmeng

    tolerance pin, diamond pin

    cool so i think this is ok then, just seemed a little weird when I first did, thanks for the help
  12. rhmeng

    tolerance pin, diamond pin

    ohh yea thats a good point I should include that, that would be all I could do tho I think..
  13. rhmeng

    tolerance pin, diamond pin

    part 2http://files.engineering.com/getfile.aspx?folder=2e043212-b640-4f92-99d0-0a1716b858a0&file=part_2_with_pin_and_diamond_pin.JPG
  14. rhmeng

    tolerance pin, diamond pin

    I think this is right but I am hoping to get some input. I have two parts (part1 and part2)that mate to eachother via a pin and hole (datum B) and a diamond pin and hole (datum C). Each part is aluminum and I am using tightly toleranced bushings for the holes in part1, and a tight toleranced pin...
  15. rhmeng

    using 3 diamond pins as locating for optics?

    pmarc, not sure if i follow. Are you saying use a pilot diameter and then hold the two parts together and then drill them both at the same time? Is that what you are getting at? How would two holes mate with eachother? And Im with JNieman that I think that two non perpendicular diamond pins...
  16. rhmeng

    using 3 diamond pins as locating for optics?

    @JNieman I was not meaning that I wanted to press fit pins into bushings. I was talking about on one part press fitting the pins, and then on the mating part press fitting in bushings that would then mate with the pins for alignment. I was hoping someone had some insight on the three diamond...
  17. rhmeng

    using 3 diamond pins as locating for optics?

    I saw a callout for how 3 diamond pins can be used to center two parts relative to each other Link (also attached screen shot). I am trying to wrap my head around how using this 3 diamond pin design is any better/more accurate than simply using a pin and slot design. My application is...
  18. rhmeng

    Spots on Fully Annealed Copper Pinch Off Tubes

    We use new IPA straight from the bottle every time we clean these. We also use new water every time we wash new parts. After the parts go through the cleaning, they are transported into a clean room while they are submerged in fresh IPA, then they are put on a clean room bench under a hood and...
  19. rhmeng

    Spots on Fully Annealed Copper Pinch Off Tubes

    additional picturehttp://files.engineering.com/getfile.aspx?folder=f72cd58e-39f7-4307-b256-a552d1fb1483&file=IMG_20161018_112134056.jpg
  20. rhmeng

    Spots on Fully Annealed Copper Pinch Off Tubes

    We use fully annealed C10100 copper tubing as a pinch off tube for hermetic sealing applications. The tubes we are receiving have already been soldered into a housing, and then a mechanical abrasive is used to rub off the oxides created during soldering. On the tubes that we are receiving, we...

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