A DYI Guide to Making a 1911 Recoil Spring Tester

Discussion in '1911 Gunsmithing' started by Jeffrey51, Oct 15, 2020.

  1. Jeffrey51

    Jeffrey51 Active Member

    98
    Aug 26, 2020
    Need to figure out a Recoil spring weight? Want to see how much a spring has weakened?
    Here’s how. Cost about $20.
    Or - Jeffrey Makes a Thing…
    [​IMG]

    I have several unmarked springs I’ve collected over the years. No idea how heavy they are.
    I’m also curious about how much oomph the springs in some pistols have lost over time.

    Obviously I need a spring tester!

    I’ve seen some designs that just have the scale, a rod or a tube, and you pull on the thing till you reach some mark on the rod. Harder to do in practice. At lest for wimpy old guys like me. Seems like there outta be a more better way.
    Trying for an exact fit seems tasking, so, heeding a wise man:
    “If you can’t make it perfect, at least make it adjustable”

    Parts.
    5/16” smooth steel rod. Hardware store 4’ for $5.95
    5/16” coupling nuts. Hardware store. 3 pack for $2
    5/16” and ¼” nuts. From the junk box.
    ¼” threaded rod or a long carriage bolt. Junk box, or from hardware the store (2’ for $3).
    6.5” (or so) of Aluminum (or iron) 90 degree angle metal. Mine is .125” thickness – 1” Legs. But anything would work as long as it wont flex. Junk box or buy from hardware store.
    2x4 board. About 23” long, Scrap pile.
    (4) ¼” Nuts, washers, and bolts - long enough to bolt angle metal to board. Junk box.

    Fish weight scale. 110lb. Amazon. $11.
    https://www.amazon.com/gp/product/B07ZGGWBWR/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

    [​IMG]

    It even comes with a built in tape measure, so you can check the at rest length of a spring (or a fish if you really want to).

    Tools:
    Basic stuff. Drill & bits, Hacksaw, Saw to cut 2x4, file, and a vice to hold the rod.
    5/16” Die to thread the 5/16” rod. From a cheapo set I got years ago.
    After you get the scale, test it with some known weights. These things (according to the reviews) are often off. Mine was fine using some dumbbells in the 5-25lb range.

    Prep the Parts
    Open up the hook eyelet on the fish scale and remove it.
    Cut the 2x4 to 23” or so.
    Cut the Angle iron (angle Alum?) so you end up with two pieces that almost span the 3.5” width of the 2x4. Smooth off the rough stuff from the cut with a file.

    Measure the center height of the fish scale weight connection. Mark that along one of the angle brackets.
    Find the center of the bracket and pop a divot with a punch (or nail) to center the drill bit on.
    Drill a 5/16” hole in the bracket. Wohler it out (Machinist term) if needed so the rod slides freely.

    [​IMG]

    Cut a section from the 5/16” rod. Make it long enough to clear an unstressed spring. Taper each end with a file, so the die will start easier.
    Clamp the rod in a vice. Grab your favorite lube and goop up the end of the rod and die threads.
    Make about .5 inch of thread on each end. Check to see if the 5/16” nuts work on the threads.

    The rod I got was pretty rough. So I chucked it in a drill and ran some wet/dry grits up to 800g then hit it with some car polish to get a smooth finish.

    Cross drill one of the coupling nuts close to the end with a hole big enough to run some heavy wire through. Coat hanger or some 14g solid copper worked for me.

    [​IMG]

    Attach the nut to the fish scale. I used coat hanger and left enough room to slip it off. Just so I could use the scale for other things.

    Remove the Scale handle by unscrewing the little screws on the inside of the plastic handle (you mileage may vary). This holds the plastic covers on the handle. Then remove the screws that affix the metal handle to the scale itself.

    Turns out on mine I didn’t need to pull the rod out of the scale body. The screws at the ends were all that’s needed. Mine were in so tight, I thought something else was going on.

    Drill a hole in the center of the handle to run the 1/4” rod through. Make sure you have enough plastic to support things without bending. Use a thinner rod if you think you need it. The handle on the scale I got has metal on the inside. I checked it first with a magnet.
    [​IMG]

    Take the second angle bracket and make a notch in the center of one of the sides to accommodate a sideways slip fit of the ¼” rod from the handle of the fish scale.

    Make a template from index card or paper.
    Make a line 1.125” from one end. For measuring Commander Springs.
    Make a second line 1.625” from the same end. For measuring Gov. Springs.
    Optional - Make a third line 3.86 from the same end (not sure of the length). For measuring Gov. Springs at battery. My best guess.

    I never found a reference for this.
    If anyone actually knows what this is supposed to be, let me know.


    [​IMG]

    Lay all this stuff out on the 2x4. I’m tempted to say – “put it together so it looks like this”….
    Spin the nuts onto the bolt in the handle. Space them along so they are close to the correct template marks.
    You can see where this is going. Get it all laid out to your satisfaction.

    Mark the position of the two brackets.
    Drill holes in the brackets and 2x4 to securely mount the brackets.
    Counter sink some holes on the bottom so the bolt heads don’t stick out. Mount the brackets.

    [​IMG]

    Run the rod through the end bracket. Mount the template so it corresponds to the inside of the rod bracket. Connect the coupling nut to the scale.

    Now make final adjustments to the bolt in the scale handle so you are dead nuts on the indicator lines on the template when the handle bolts are in the top bracket.
    I added a knob at the end. It doesn’t adjust anything. It’s just something to hold on to when pulling the spring into position.

    All Done!
    Slip a spring in there and see what she reads.
    Make any final adjustments to the handle nuts so the length matches to the template under load.
    I used 3 locations so I could test the at Compressed positions for a Commander and Gov. Also the starting compression for a Government.

    You could make this way simpler and just use a single nut or knob in the Government compressed position. But heck, anything worth doing is worth overdoing.
    A drop of Locktite on the threads will keep the nuts in place if you decide not to use a pair of nuts to lock the location like I did (as seen in the Pics).

    Pic of scale reading an 11lb spring
    [​IMG]

    Just how compressed does a Gov. Spring Get?
    Way Compressed!
    [​IMG]

    After seeing this, I started pulling those little buffer thingies out of my guns.

    Now I’ve shown you mine.
    Another shot of the end bracket and the 3 positions for measurement.
    [​IMG]

    Now show me yours!
    Just how much have your springs faded?
    And I’m sure some of you can improve on the design!
    Remember it isn’t a thread without pictures.
    Some random spring measurement will happen in a few days.
    All the Best,
    Jeffrey
     
    Last edited: Oct 21, 2020
  2. Magnumite

    Magnumite Active Member

    141
    Feb 20, 2012
    Nice contribution. Clean setup. Thank you. I use the marked rod and scale you mentioned.


    After seeing this, I started pulling those little buffer thingies out of my guns.

    Need not be concerned about over compression. The slide in battery position will yield a little extra force but the slide back compressed length will be the same with or without a buff. The recoil spring tunnel of the slide determines recoil spring compression dimension. A little from the plug if the front face of it is abnormally thick. Haven’t seen that yet but....
     

  3. Badabing11

    Badabing11 I gotta have more cowbell

    Sep 6, 2015
    Brilliant!
     
    TangoWhiskeyFoxtrot likes this.
  4. Jeffrey51

    Jeffrey51 Active Member

    98
    Aug 26, 2020
    You are correct. After I though about it, I realized the buffer stops the slide the exact same distance away as it moves the spring out from the end (minus the little bit the buffer squeezes down when hit).
    I have them in my shooters and never had a problem.

    If anybody knows what the at battery spring length is supposed to be. Could you let me know?
    I'd like to do a series of tests on new springs to see how much spring load is at the two positions. Thanks.
    All the Best,
    Jeff
     
    Last edited: Oct 22, 2020
    TangoWhiskeyFoxtrot likes this.
  5. Badabing11

    Badabing11 I gotta have more cowbell

    Sep 6, 2015
    You might file for a patent in that.
     
  6. Jeffrey51

    Jeffrey51 Active Member

    98
    Aug 26, 2020
    Snort!, I wish. I'm sure some patent fishing SOB has already done something.
    Wait - I know! I'll start a kickstarter campaign and disguise some of the cheap stuff with some 3D printed plastic.
    Initial offering only $150 each!!! Money back return guarantee, (minus $45 shipping and handling).
    I'll need to work up to 250K bucks in funding before I start production.
    Thanks for the kind words,
    All the Best,
    Jeffrey
     
    Last edited: Oct 22, 2020
  7. Wildcat Creeker

    Wildcat Creeker Well-Known Member Supporting Addict

    960
    Jan 26, 2012
    Just an opinion here, but this looks good enough to be a "sticky" thread.
    Thanks for posting this Jeffry51.
     
  8. TangoWhiskeyFoxtrot

    TangoWhiskeyFoxtrot I do not consent.

    Dec 28, 2017
    Great post. Very well done little device there. Always cool to see folks develop tools.

    Sent from my SM-A102U1 using Tapatalk
     

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