Work in Progress: Ergo XL

Discussion in 'Show off your homemades!' started by MountainStorm, Oct 17, 2013.

  1. MountainStorm

    MountainStorm Termite

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    Little something I had buzzing in my bonnet: to make a sling shot that I would be happy with, a pocket friend if you will...a constant companion for my rambles in the woods. Not sure if this is "The One" because I have yet to band it...much work left to get it ready for some finish. But I thought you might like to see it in the rough.

    BONUS PATTERN as requested by Doc BV...sort of. I took a nice clear shot of the pattern I used for my last frame just in case anyone liked it and wants to give it a whittle.

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    Here's the pattern I started with on my last frame and I used it to get going.

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    The progression toward the Ergo XL. I find paper does not give me good feedback in hand. I used scrap ply.

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    I varied from the pattern but the overall idea is there.

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    Little areas have a significant impact on the feel.

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    I developed the shape by handling it, looking for hot spots and rasping out material.

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    I designed the frame for Bow Shooter Grip

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    But I incorporated a thumb notch and altered the shape to allow for a position shift to Vertical Grip. Looks like a sore thumb waiting to happen:eek:

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    And I can choke up on the grip with the index finger to resist strong bands.

    After taking these shots I spent many hours removing burn marks and rasp gouges by blade scraping and went after it with 220 and it is almost ready for finish. Almost.

    More to follow;)
     
    Last edited: Oct 17, 2013
  2. onnod

    onnod Im from Holland, isnt that weird?

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    looks good!! can't wait to see it finished!
     

  3. xXdoomXx

    xXdoomXx Junior threadjacker ag. J

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    Looks amazing right now
    Lj
     
  4. FIAAO

    FIAAO Failureisalwaysanoption

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    Cool! Looks really ergonomic, and the pattern on the forktips are very nice-looking, can't wait to see this finished!
     
  5. MountainStorm

    MountainStorm Termite

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    Sad to say I have other tasks I must attend.

    That's good to hear.

    Going to try a dome tip this time. The ancient router bit left serious burns all over the forks. After this photo I spent hours getting the burns off the tops. My hands are still sore:eek: Need new bits!
     
  6. MountainStorm

    MountainStorm Termite

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    [ame]http://www.youtube.com/watch?v=EyNe2F7Ge4Q[/ame]
     
  7. Brazilviking

    Brazilviking Thread Hijacker

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    What a crazy monster shooter! Nice shape! Original!
    I like it!
     
  8. rock slinger

    rock slinger I rarely shoot rocks!

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    Nice. I really like it
     
  9. Ryan Wigglesworth

    Ryan Wigglesworth Senior Member

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    how bout cardboard instead of ply to get a better feel?


    looks fancy btw thanks for sharing :)
     
  10. MountainStorm

    MountainStorm Termite

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    Thanks.

    I appreciate that.

    I did not have any... but that would probably work.

    Here's the way she looks after the initial finish.

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  11. MountainStorm

    MountainStorm Termite

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    [ame]http://www.youtube.com/watch?v=_6rOIUi-h50[/ame]
     
  12. Thistle

    Thistle RESIGNED

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    [​IMG] MountainStorm! Very lovely ergo compact shooter. Beautiful wood grain. Very nicely sculpted. Nice primitive look about it. It kinda has a face, don't you think? I see a brow line, nose, mouth, chin, goatee….

    I just REALLY like this. Whatever works for you. Very well done, Blue Ridge man! And the FINISH is perfecto!

    BTW, I'm really liking that Rosewood. I'd like to know a little bit more about that, if you don't mind -- it's character...
     
  13. MountainStorm

    MountainStorm Termite

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    Thank you for brightening up my thread.

    Here is some info from the Wood Database http://www.wood-database.com/lumber-identification/hardwoods/tiete-rosewood/

    Common Name(s): Tiete Rosewood, Patagonian Cherry, Sirari
    Scientific Name: Guibourtia hymenaeifolia (syn. G. chodatiana)
    Distribution: South America
    Tree Size: 130-165 ft (40-50 m) tall,3-6 ft (1-2 m) trunk diameter
    Average Dried Weight: 59 lbs/ft3 (945 kg/m3)
    Specific Gravity (Basic, 12% MC): .76, .94
    Janka Hardness: 2,790 lbf (12,410 N)
    Modulus of Rupture: 15,830 lbf/in2 (109.2 MPa)
    Elastic Modulus: 2,030,000 lbf/in2 (14.00 GPa)
    Crushing Strength: No data available
    Shrinkage: Radial: 4.0%, Tangential: 7.0%, Volumetric: 9.7%, T/R Ratio: 1.8

    What to do with all that data? Well compare it against something like Bubinga (Brazilian Cherry)

    Common Name(s): Bubinga, Kevazingo
    Scientific Name: Guibourtia spp. (G. demeusei, G. pellegriniana, G. tessmannii, etc.)
    Distribution: Equatorial Africa
    Tree Size: 130-150 ft (40-45 m) tall, 3-6 ft (1-2 m) trunk diameter
    Average Dried Weight: 56 lbs/ft3 (890 kg/m3)
    Specific Gravity (Basic, 12% MC): .72, .89
    Janka Hardness: 2,410 lbf (10,720 N)
    Modulus of Rupture: 24,410 lbf/in2 (168.3 MPa)
    Elastic Modulus: 2,670,000 lbf/in2 (18.41 GPa)
    Crushing Strength: 10,990 lbf/in2 (75.8 MPa)
    Shrinkage: Radial: 6.0%, Tangential: 8.2%, Volumetric: 13.9%, T/R Ratio: 1.4

    And we can see that it is somewhat denser and harder but slightly more brittle.

    What about something really really hard like Purple Heart

    Common Name(s): Purpleheart, Amaranth
    Scientific Name: Peltogyne spp.
    Distribution: Central and South America (from Mexico down to southern Brazil)
    Tree Size: 100-170 ft (30-50 m) tall, 3-5 ft (1-1.5 m) trunk diameter
    Average Dried Weight: 61 lbs/ft3 (980 kg/m3)
    Specific Gravity (Basic, 12% MC): .79, .98
    Janka Hardness: 2,390 lbf (10,630 N)
    Modulus of Rupture: 22,000 lbf/in2 (151.7 MPa)
    Elastic Modulus: 2,586,000 lbf/in2 (17.83 GPa)
    Crushing Strength: 13,350 lbf/in2 (92.1 MPa)
    Shrinkage: Radial: 3.2%, Tangential: 6.1%, Volumetric: 9.9%, T/R Ratio: 1.9

    Here we have one of the Queens of the Hard Woods. The crushing strength is so very high with Purple Heart it is like the metal of woods. But the Tiete Rosewood is harder and heavier. And Bubinga is harder to tear apart...so they all have their superiority.

    So is Tiete Rosewood a good wood for our purposes? It will suffice...it is heavy in the finished prodcut and hard to work, but that same hardness yields a glassy surface even without finish applied. And it is not a true Rosewood (Dalbergia) but it is lovely to behold.

    Hope that piqued your curiosity.

    -RW
     
    Last edited: Oct 17, 2013
  14. Thistle

    Thistle RESIGNED

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    [​IMG] Fantastic!

    Thank you for digging all this info this up, Mountain Storm. I've got a weak spot for Purple Heart, but this Tiete Rosewood is stunning. I heard you say "??? Rosewood" in the vid, but couldn't quite form that first word.

    I'm glad you decided to go natural on this with that finish. Very wise decision. Again, very beautiful.
     
  15. MountainStorm

    MountainStorm Termite

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    I love Purple Heart as well. I made myself a sword cane from Purple Heart a while back....

    [ame]http://www.youtube.com/watch?v=OTAsha4bLGg[/ame]
     
  16. Jeremy

    Jeremy Senior member who totally rocks a pink Scout! Pink

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    Looks amazing.
     
  17. Brazilviking

    Brazilviking Thread Hijacker

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    In Brazil it is called Jatoba mirim. Protected wood!
     
  18. Courier

    Courier Senior Member

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    This slingshot has a very different and innovative shape. I like it!
    Also the color is really beautiful.
    All in all great work, MountainStorm! :)
     
  19. Tilia

    Tilia Junior Member

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    very interesting shooter, beautiful made out of nice wood
    there are a lot of great slingshot builders here.....
     
  20. Antraxx

    Antraxx #7

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    What a unique design...and a super-sweet finish.

    Nicely done!