Sightron parallax assist knob

Discussion in 'Scopes, Optics, LRFs, Spotters, BoreScopes' started by Stray8, Jan 13, 2018.

  1. Stray8

    Stray8 Silver $$ Contributor

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    Recently started 3D modeling/printing and decided to create a knob to increase the leverage on the hard to turn 10-50x parallax. I know this has been produced in aluminum in the past due to other people having this issue. The markings on the knob also leave something to be desired so I put some marks that can be painted as well. I have attempted 3 drafts and so far draft 2 and 3 are perfectly functional and fit tight in the teeth on the knob. Draft 1 was too tight due to material printing dimensions needing to be adjusted. Also has a hole that spans the joint with recesses for a screw and nut to lock it on.

    The drafts were printed in PLA with 200 micron layers and 20% infill. Ended up printing at 100.6-100.7 scale to get the fit right. Appears plenty strong for the job. If anyone is interested in the STL files let me know.

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  2. dedogs

    dedogs Gold $$ Contributor

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    Will you be doing these for any other scopes, i.e. Nightforce, Leupold etc.?
     
  3. pittbull46

    pittbull46

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  4. pittbull46

    pittbull46

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    would you sell one?
     
  5. Stray8

    Stray8 Silver $$ Contributor

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    I don’t currently own scopes of those brands. It wouldn’t be difficult to change it for them, but without a knob to test it would be difficult to know if the print would fit correctly.

    If you wanted to modify a file yourself though, I could get you an STL file that would be close from pictures/measurements.
     
  6. Stray8

    Stray8 Silver $$ Contributor

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    I would, I’m still currently trying different outside shapes to make it easier to grip and final design may change. Also, I would hate to sell you one made out of PLA because it may deform if you left it in a hot car that got close to ~140F. I do plan on printing in a more heat stable plastic though.
     
    foxguy, nmkid and dmoran like this.
  7. pittbull46

    pittbull46

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    I would be interested please let me know
     
  8. 6MMsteve

    6MMsteve Gold $$ Contributor

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    shoot me a pm when you get the R&D finished and a price if you don't mind, I'm interested. Thanks Steve
     
  9. Punkinslinger

    Punkinslinger Gold $$ Contributor

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    Me also, please
     
  10. JLT

    JLT Gold $$ Contributor

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    Piling on ... interested as well. I have more than a handful of SIIIs.

    Nice work. Thanks!
     
  11. Stray8

    Stray8 Silver $$ Contributor

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    Would someone with an SIII 10-50 mind measuring the max diameter of their parallax knobs? I want to see if there is significant difference between individual scopes.
     
  12. pittbull46

    pittbull46

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  13. pittbull46

    pittbull46

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    upload_2018-1-14_12-4-43.png is this what you are looking for max dia. is 1.254
     
  14. Punkinslinger

    Punkinslinger Gold $$ Contributor

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    My max dia on two 10-50X 60 is 1.469 2-3 years old
    My max dia on two 8-32 is 1.252 5-7 years old
     
  15. Stray8

    Stray8 Silver $$ Contributor

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    What model scope did you measure?
     
  16. Stray8

    Stray8 Silver $$ Contributor

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    1.468” is what my 10-50x measures so we are right on there
     
  17. Stray8

    Stray8 Silver $$ Contributor

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    Here are the current/final versions of the parallax knob extensions. I added teeth because the original didn’t have enough ridges if your hands were sweaty. The large version is ~3.2” diameter and makes moving the knob very easy. However I found it could possibly obstruct the rear of a left port, and this was with my high TPS rings. So, I made a smaller version that makes it ~2.5” for use with left loading ports or super low rings. Still a great improvement but not as much leverage as the large.

    Also, the screw hole was eliminated from the designs because it is not necessary for a tight secure fit.

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    Last edited: Jan 15, 2018
  18. Mozella

    Mozella

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    Here's an option for those who don't have a 3 D printer. This side wheel is available on Amazon for eighteen bucks, but it doesn't fit my Sightron III. However, I enlarged the ID of the hub just a little bit using a Dremel tool and a cylindrical cutter.

    It's not perfectly concentric, but the cut is on the inside so it doesn't show and it's a very low RPM device, so it need not be perfect. Just keep whittling away at the aluminum until it's large enough and then modify the rubber hub for a nice fit or toss the hub and wrap your scope knob with a couple layers of electrical tape, depending on the OD of your scope knob. It's pretty easy.

    Later on a friend cut some for his scopes and some of my other scopes on a milling machine, but a lathe would be even better.

    The wheel is pretty nice and it will be hard to beat the $18 price tag no matter what path you take.

    upload_2018-1-15_10-11-34.png
     
  19. pittbull46

    pittbull46

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    SS111 8x32 didn't think they were dif
     
  20. Stray8

    Stray8 Silver $$ Contributor

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    I haven’t seen that one, looks like it is a pretty good DIY option. Since people had shown interest I was going to sell them for $15 shipped with tracking once I get them printed in ABS. Could also do some custom diameters or hole patterns if requested. I will share the STL files for free any time though.
     

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