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  • You know this, but...... the tach needs to read just ONE bright spot per rev.... if it reads more, it will read 2x, 3x, etc vs actual rpm.
    4357 2773 5150 9120 9135 8645 1007 1190 2133 9120 5942

    Keep eye on ball.
    Hashim Khan

    Everything not impossible is compulsory

    "There's no pleasing these serpents"......Lewis Carroll

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    • Originally posted by J Tiers View Post
      You know this, but...... the tach needs to read just ONE bright spot per rev.... if it reads more, it will read 2x, 3x, etc vs actual rpm.
      Yeah... I did read the manual, such as it is, and I understand the theory. Still don't trust it though, even though the results are consistent. I'll take it to work tomorrow and find something that spins at a known speed, for sure, just to prove it to myself.
      http://fixerdave.blogspot.com/

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      • Originally posted by fixerdave View Post
        Yeah... I did read the manual, such as it is, and I understand the theory. Still don't trust it though, even though the results are consistent. I'll take it to work tomorrow and find something that spins at a known speed, for sure, just to prove it to myself.
        If you can be sure of the known speed, I'd put money on the tach giving a different reading. I put a cheap digital tach on my geared head lathe spindle. Ran the machine through all speeds and the tach was off on each one. The good news, the error is consistant. The bad news, I don't know which is correct, the lathe or the tach.
        “I know lots of people who are educated far beyond their intelligence”

        Lewis Grizzard

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        • There are just three things that affect the accuracy of an optical tach.

          1) it has to get a good clean signal from the shaft

          2) it has to count "one" for every clean input signal

          3) it has to count them for the exact correct time duration, and display the result.

          #1 is a variable, of course. Number two should be good if #1 is. There should be no question about #3, but that depends on the way the time period is determined (the time base). A cheap tach may use an R-C oscillator, and be only as accurate as that is set up, plus they are often temperature dependent due to poor choice of capacitor. A quality unit will use a crystal or ceramic resonator, often the same type used in watches, which are accurate, and usually quite stable against temperature.

          A consistent error can be "percentage consistent", always off 1%, or whatever, that is a matter of the time base being off. A consistent number of counts must be somewhere in the display or counting circuit. In a micro-based unit (most of them) it may be an error in the math, or some error in presetting a register.
          4357 2773 5150 9120 9135 8645 1007 1190 2133 9120 5942

          Keep eye on ball.
          Hashim Khan

          Everything not impossible is compulsory

          "There's no pleasing these serpents"......Lewis Carroll

          Comment


          • Bit of scrap cleanup and pulled ugly Betty out of deep storage to get it ready for sickle bar and front weed cutter. Forgot it had high/low and hydraulic lift


            "Good judgment comes from experience, and often experience comes from bad judgment" R.M.Brown

            My shop tour www.plastikosmd.com

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            • Actually it’s what I did the last 3 days. I did all the wood parts myself with a little help from my step son for assembly of the slide pieces. Really good quality fasteners. Decent instructions. The wood was ok too.
              A few minor hiccups along the way but for the most part it was a good project to prove to myself, that at 13 weeks out from the ICU, I’m back from my quadruple bypass.
              Then it’s back to my units at the refinery 4/17.
              Last edited by Tim The Grim; 03-30-2019, 07:25 PM.
              Illigitimi non Carborundum 😎
              9X49 Birmingham Mill, Reid Model 2C Grinder, 13x40 ENCO GH Lathe, 6X18 Craftsman lathe, Sherline CNC mill, Eastwood TIG200 AC/DC and lots of stuff from 30+ years in the trade and 15.5 in refinery unit operations. Now retired. El Paso, TX

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              • Woke up last night about 3am to the well pump running. And running, and running. Got up and shut it off, and watched the pressure drop to zero. I can't even prime it again (shallow well one line pump), so either the foot valve is stuck, or there's a leak somewhere between the pump and the well (nothing was leaking/running in the house). Greaaaaat. Ground is still frozen... I was actually going to replace the well line this spring because I want to relocate the pump and pressure tank away from the electrical panel (currently right beside it) because I want to replace the panel too. Surviving on creek water/roof runoff for toilet flushing, and bottled for drinking and cooking for now. Tomorrow I pop the lid off the well (pouring rain today) and hope it's just the foot valve.

                If it's not the foot valve, I bought some 3/4" pex that I'm going to try and run down inside the old pipe into the well. It's only about 30' from the house, and the well itself is only 25' deep. I'm hoping the 3/4" pex, while not ideal, will get us by the next couple weeks until the ground thaws and this can be a couple hundred dollar problem I can tackle myself, not a couple thousand dollar problem I need a hydrovac truck for....

                When I do dig it up I'm going to run conduit from the well to the house, under the basement floor to the new pump location with big sweeps. That way I can just pull a new 1 piece line whenever I need to (if I ever need to). I just wanted to do it in a couple more weeks, not right now.

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                • I used a piece of 4" Big O for a conduit when I excavated my well head to replace the lines to the well and left a piece of rope in it.
                  Lots of room for another pipe if I ever need to replace them again or to pull in wire if I ever go to a submersible.
                  Cheers,
                  Jon

                  Comment


                  • Originally posted by Jon Heron View Post
                    I used a piece of 4" Big O for a conduit when I excavated my well head to replace the lines to the well and left a piece of rope in it.
                    Lots of room for another pipe if I ever need to replace them again or to pull in wire if I ever go to a submersible.
                    Cheers,
                    Jon
                    I was thinking of 2" PVC, but like the big O Idea better, thanks. Bigger, and easier to work with. Having a coffee, then I'm going out to pull the cap off the well (if the tractor will start) and have a look. Hopefully it's the foot valve but I don't think so. I think the leak is just on the other side of the foundation because I can fill up the prime hole and it takes almost a pitcher of water, then leaks down to the same point every time.

                    When they put the lines in they buried 2. But they've already used and abandoned one. I'm going to try and snake the 3/4" pex down that line into the well and hope there are no barb fittings along the way. Knowing the guy who did it though the 30' run is probably made up of 10 3' sections of scraps from work......Just the way he did things around here..... House was built in '73 and is full of surprises

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                    • Got the cover off by hand and the water was about 4' from the top.
                      This is after I already pumped about 2' of water out. Never seen it so high.

                      Ladder set up. Water pumped out enough to work. Ready to head down.

                      All done down here

                      Done and holding pressure. Finished just in time for the motogp race.

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                      • Got back from an architect summit at Jones Farm in Hillsboro, Oregon. Was a great trip and the room service with Fish'n'Chips and a couple cream Sodas was great!



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                        • Rolled and mowed the lawn twice... potted plants, continued garden cleanup. Two weeks ago I was standing on ice pruning; now it full summer!

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                          • Lakeside53--I envy you. There was still 10" of snow in my yard the day before yesterday, and it snowed another 3" last night. Just call me the Eskimo Kid!!!
                            Brian Rupnow
                            Design engineer
                            Barrie, Ontario, Canada

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                            • Same as Lakeside. Yard work, Greenhouse getting ready for seeds, clean-up the water feature/pond and paint some outdoor plant stands. I actually machined 12 delrin washers.

                              Tomorrow will be some machining for a street clock. Weather is such that I do not need the heat or cool of the new mini-split.

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                              • I have been trying to use some old kitchen cabinets that I got for free last summer, to help organize some of the stuff in my workshop house. Most of them had been sitting outside under a tarp for eight months, and being made from particle board, they need a lot of work.


                                I installed a barrier in my Honda Fit so I can safely have Mr Tibbs ride in the back. Noy sure he likes it all that much:


                                I moved the ugly old woodshed about 2 feet to make way for the 8' x 12' shed I plan to build.


                                It reached 70F yesterday, and crocuses are everywhere. I have also been doing some major yard cleanup. Mr Tibbs enjoys being outside, especially now that the weather is finally Spring-like (although it only reached 50F today, and will be in the 30s tonight)
                                http://pauleschoen.com/pix/PM08_P76_P54.png
                                Paul , P S Technology, Inc. and MrTibbs
                                USA Maryland 21030

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