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OT: Need info on Unholz-Dickie shaker table

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  • OT: Need info on Unholz-Dickie shaker table

    It's an Unholz-Dickie 106A 3/4 , a fairly small table. U-D hasn't got any info on it anymore.

    We've been using it for simple gage/vibration switch calibration now, but need to use it at higher power soon for actual vibration testing of units (random vibration and the like), and so we need to get serious about driving it and providing protections, etc.

    We are not using a U-D amplifier setup, we have available amplifiers clear up to a couple hundred kw, so power won't be an issue. but we don't have a clue what the field current ought to be, what to limit the drive coil current to, etc. U-D don't seem to know either, it was made in the 1960s, and they seem to have somewhat deliberately forgotten about it.

    We can't afford to damage it, I don't think we can get any parts for it anymore, even from U-D.

    if anyone has info that would be appreciated.
    1601

    Keep eye on ball.
    Hashim Khan

  • #2
    My wife tells me that I too, have a small obsolete Dickie. Welcome brother.

    Comment


    • #3
      Simple:
      Stick some thermocouples on the actuators. Keep an eye on the temperature while turning up the drive. Quit twisting the knob before the smoke comes out.

      Fancy:
      Stick some thermocouples on the actuators. Feed them to the A/D inputs on a I/O board readily available from many sources. Also feed the drive signals suitably reduced to the I/O board. Use Logging software to develop a profile at various drive levels and frequencies by logging the drive levels and correlating that to the temperatures. Watch out for the resonance peaks as the maximum excursion of the actuators could easily be exceeded at power levels that are safe at other frequencies.

      Use the profile to generate a drive signal via the I/O board that takes into account the resonances and previously determined signal levels.
      Free software for calculating bolt circles and similar: Click Here

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      • #4
        J Tears,

        They have somewhat deliberately forgotten about it because it's no longer supported. They don't want to be bothered and would rather sell you a new one. I run into that all the time with older equipment in the cal lab I work at. I got jury duty this Monday but hopefully Tuesday I can see what manuals I have on file for the UD shakers we have. I know we were changing them out for better/newer models but the info on what you have, well we might just have something. How big is the table? The ones we have are about 4ft on each side. I've seen ones that shake railroad cars - not kidding with that either! If I remember we might have a couple smaller ones tucked away in another area. But hey it's worth a shot to look anyway

        Eric
        "To invent you need a good imagination and a pile of junk" Thomas Edison

        Better to have tools you don't need than to need tools you don't have

        73's KB3BFR

        Comment


        • #5
          Metalmelter:

          Thanks. I suspect this is smaller than any you have. it is a 300 lb force unit, the driver overall diameter is around 20 or so inches, maybe a bit less. I won'tbe able to measure until Monday. But nothing like a 4 foot table. this is for calibrations and shaking small items. It happens we have a customer with a vibration requirement on an item we are designing for them, and so we would like to use this for that pre-qualification.

          it seems that nobody this side of Cleveland can do the test they require, but it isn't that hard, really. There is one company in Alton that has a big table, but no random capability. There is a guy in Belleville who has random, but doesn't have the bandwidth to get to 500 Hz (he does ESTA package testing).

          This table has a wider than usual bandwidth, but we don't know what we can get away with! We've only used it for testing switches and small g-force transducers.

          Originally posted by Evan
          Simple:
          Stick some thermocouples on the actuators. Keep an eye on the temperature while turning up the drive. Quit twisting the knob before the smoke comes out.
          Naturlich!

          This one HAS one thermocouple, and limit switches etc. The thermocouple is on the cooling water exit, so it is mainly for the stator. The limit switch will be tripped at the max excursion.

          Probably the better way to describe what we would like to find is specs on the unit, and some basic information, starting with a schematic of it. We did as much tracing as we could already, but you can't see inside.

          In case you have never seen one of them, they are a largish "pot" of iron/steel on trunnions, with what amounts to a large "speaker" inside, and an electromagnet field. In this case, somewhere around a third of a ton of "stuff" jammed into a small space.

          Without removing things that we don't know how to properly remove, we won't be able to verify the schematic and be sure we have the safeties all working, and that won't tell us maximums on the various inputs.
          Last edited by J Tiers; 03-28-2009, 10:21 PM.
          1601

          Keep eye on ball.
          Hashim Khan

          Comment


          • #6
            If it smokes you can probably buy what you need at the local boom box supplier. I kid you not.
            Free software for calculating bolt circles and similar: Click Here

            Comment


            • #7
              Originally posted by Evan
              If it smokes you can probably buy what you need at the local boom box supplier. I kid you not.
              That may possibly be a tad simplistic! But some of those boombox car audio devices do have the makings for a small shaker....... I (coming out of the audio biz) don't think they have any OTHER useful purpose......
              1601

              Keep eye on ball.
              Hashim Khan

              Comment


              • #8
                You might be surprised at some of the audio gear avilable now.

                Check these specs for instance for a basic subwoofer:

                Type : Dual-driver vented sub-bass system
                Frequency Response (1) : 35Hz-150Hz ± 3dB
                Drivers : 2 x 18" (460mm)/4" (100mm) voice coil, ultra-long excursion, water resistant cone
                Rated Power (2) : 2000W AES, 8000W peak
                Sensitivity (3) : 105dB (half space)
                MAXIMUM SPL (CALCULATED @ Im) : 136dB continuous, 142dB peak (half space)
                Nominal Impedance : 4 ohms
                http://catalogs.infocommiq.com/AVCat...&prodid=390835
                Free software for calculating bolt circles and similar: Click Here

                Comment


                • #9
                  J Tears

                  The units we have push somewhere in the 300 to 400 amp range to the coil which is rolled square copper tubing and water cooled all at once. We get a bit nervous mixing water with all that current! Anyway there's not much to see inside the housing. Once upside down the cap is removed via forklift and service (for us anyway) can be performed. Since I don't really get out to work on them that often I have to rely on memory from my last experience, but I think we easily get in the 30 to 50G range. But I could be way off base on that. I will talk to the guy that works magic on the UD's and see what he has to say.

                  The coils we have in the shakers I'm gonna say are about 30" dia., weigh a few hundred pounds drive a 4ft x 4ft table that floats on a layer of oil on a granite slab. When they crank the monster up to vibrate things to Mil spec it can rather interesting but LOUD!

                  I'll get back to you once I get this jury duty thing out of the way on Tuesday I hope.

                  Eric
                  "To invent you need a good imagination and a pile of junk" Thomas Edison

                  Better to have tools you don't need than to need tools you don't have

                  73's KB3BFR

                  Comment


                  • #10
                    Just took a quick look on Google and found this on ebay:
                    http://cgi.ebay.it/Shaker-Electro-dy...QQcmdZViewItem

                    Is that what you have? If so I hate to say it but I don't think I have the info your after. That's a small unit compared to what we have. But I will check none the less
                    "To invent you need a good imagination and a pile of junk" Thomas Edison

                    Better to have tools you don't need than to need tools you don't have

                    73's KB3BFR

                    Comment


                    • #11
                      Yes, that is an identical unit to ours, same model number.

                      No sweat... I figured from what you said that it was a lot smaller than what you use.

                      Our product is only about 5 kg, and we don't need (for this test) more than a small g force average, so it's ample. But the table wouldn't even make the side of a boxcar wiggle!


                      Evan, I hear you, but my first reaction to that spec set is that it is pretty much BS....... as far as real-world usage

                      You can make a speaker that can handle quite a bit of power electrically, but the kicker is that it really needs to use that power acoustically to be of any use in the real world. Unfortunately, LF audio needs huge excursions to handle even moderate input power, which is one reason why the vented box was developed. i'd have to do some calculations, which I am too lazy to do at the moment, but I suspect the power handling quoted has some definite restrictions and conditions on it.

                      And, let's see..... a 4" coil is roughly 12" around, so two is 24". That suggests the coils would need to handle 83 watts per inch of coil length...... it's very optimistic, to say the least...... with sufficient magnet structure mass, it might be do-able. They claim to do it, anyhow..... We found our best units were capable of about half that at most.

                      Yes, I've done quite a bit of multi-driver speaker design for PA systems.......
                      1601

                      Keep eye on ball.
                      Hashim Khan

                      Comment


                      • #12
                        J Tiers

                        If you can't find the info you need for your shaker, you might try the Largo, Fla division of Raytheon. When I worked there about 5 years ago, the vibration and environmental testing group did a lot of outside customer testing. I believe they were able to do random frequency shaking in three axis. Don't know if this number is still good or not: (727) 381-2000. When I was there the contact person would have been Paul Preston.

                        Hope this helps.
                        No matter where you go, there you are!

                        Hal C.

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                        • #13
                          We, or the customer, will certainly be using such a service for certified testing. But we are after doing the pre-qual here, where we have our full support, local machine shop services (some of which is me), etc.

                          Any far-away service means travel to it. Then if ANY issues come up, you are generally totally unable to handle them, and will have to travel BACK yet again to re-test at great expense...... How to blow a budget without really trying.......

                          if we save ONE travel and test cycle, we have saved the cost of the equipment we have.

                          We'll be using this equipment, we just want to get some basic info on it so we can correctly operate it nearer to its limits.

                          Thanks for the tip, though.
                          1601

                          Keep eye on ball.
                          Hashim Khan

                          Comment


                          • #14
                            J Tears

                            I followed up on the model shaker table and what we have is newer and larger. I can't help you in your search for specs unfortunately. It's also hard to believe U-D doesn't have an older engineer on staff that may know the whereabouts of some drawings or specs. The tables come with their own set of drawings, specs, etc. Ask to speak to an engineer there and try and avoid the front desk and obvious folks that only want to sell you something new.

                            Best of luck!

                            Eric
                            "To invent you need a good imagination and a pile of junk" Thomas Edison

                            Better to have tools you don't need than to need tools you don't have

                            73's KB3BFR

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                            • #15
                              JT:

                              Try checking with a local university mechanical engineering department, as the U-D shaker table is a very commonly used device in their mechanical measurements labs

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