Question for an Engineer and Laser Driver

Discussion in 'Laser Talk' started by David Mast, Sep 29, 2016.

  1. David Mast

    David Mast New Member

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    I'm turning a wayward hull in to a working boat(non-class). I'm going to make a BoomVang something like the race versions. Since I have not yet been able to get one in hand.... How thick are the Stainless side plates????? I realize that the design, cross pylons placements and other thing will influence the stiffness required ......but ballpark Gauge or actual thickness measurements if you have a Mic handy
     
  2. LaLi

    LaLi Active Member

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    That's somewhat of an oxymoron. What's your reason to go outside the rules?
    Could you be a bit more specific?
    Of what? If you're talking about the old Allen vang cleat block, it's made of cast aluminium. Do NOT drill any holes in it; if you want to attach extra sheaves to it, it's much easier to tie them to the pin or the swivel, or replace the pin with a bolt that's long enough to attach cheek blocks.
     
  3. David Mast

    David Mast New Member

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    As in( I thought I splained)....I have a bare Hull, so it's not a working sailboat....just a poorly designed rowboat, at this point.
    I don't care about fitting it with all spendy OEM parts to stay inside the "rules". Fun, not campaigning (I know many here don't understand that)
    Harken XD, Holt Alen or Nautos CX(I sort of like that design)
    Of the Stainless side plates of the Vang Assy (don't know how to be much clearer about that). Wasn't looking for opinions on assumption that I was modifying this or that. I wasn't looking to play 20 questions about my motives, skill level, whether I went to an Ivy League of Public school. The only holes I'm drilling are the ones I design into a sheet of raw stainless plate. Just looking for a answer an Engineer might give, like "The Harken side plates are T-316 .048"(18Ga.) except the cleat arm, which is .060" (16 Ga.)
     
  4. LaLi

    LaLi Active Member

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    Sorry, I really didn't understand what you meant at first. So you're really going to build an imitation vang cleating fitting from scratch? Maybe you've already made up your mind, but it still sounds like a waste of time and effort. If you want to go the inexpensive way, get the old Allen cleat block. And if you really want to go outside the class rules, you can use an off-the-shelf fiddle cleat block as a base, or even take the line to the deck (which would probably be the cheapest way of all).

    By the way, the side plates on the new Allen vang cleating fitting are 1.3 mm thick.
     
  5. David Mast

    David Mast New Member

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    Well I always say...Why buy some over priced mass produced kit or some used junk with unknown issues... When you can build a slick custom doo-dad for less.
    I turn some pretty nice sheaves. I already have sheets of stainless, Delrin rod and stainless hardware up the whazoo. So there you go again, assuming that an off the shelf fiddle block is cheaper than me making one, if that's what I wanted. When you have tools and materials and AutoCad at the ready, you can make anything you can imagine, for the price of your time...and I have plenty of free time.

    Thanks for the Allen Vang measurement. My guess is that's 18Ga...Maybe (1.2192 actually) I was thinking 16Ga. was going to be overkill

    I think I'm going to make something like the Nautos CX but put a swing arm cleat on it like the Harken
     
  6. chemprof

    chemprof Member

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    My Harken vang has 0.060 in (1.52 mm) thickness. The plates are formed (bent) in the two pin attachment points, I assume to increase strength at these stress points. The plates on the swiveled cleat assembly are ca. 0485 in (1.28 mm). -- Ed
     
  7. David Mast

    David Mast New Member

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    Thank Ed......Yeah the side plates are cold forged to create a box structure to make it stiffer( a superior design feature to the other Vangs) It surprises me that the swing arm is thinner than the side plates, especially with their box structure, though the swing arm is trickier to form and bolting on the cleat forms a box structure, as well.
    Which reminds me......is the cleat a micro(1- 7/8"wide #468 or 471) or is it a Cam-Matic(2-9/16 wide #150 or 365)??? looks like a micro.
     
  8. LaLi

    LaLi Active Member

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    The shaping of the side plates on both the (new) Allen and Harken is more likely simply about making the other parts and connections fit. The Allen plates are about 8 mm apart, except 4 mm at the mast tang pin and 11 mm at the sheave intended for the primary line.

    The cleats for both have 27 mm fastener spacing.
     
  9. chemprof

    chemprof Member

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    The cleat is 1-13/16" wide at the cams; the bolts are 1-1/16" wide, the base plate is 1-57/64". It is a micro!

    I too thought it strange that the swing arm is thinner, but it is! Some of the side plate has a bit of a lip on the edge, probably due to the forging you mentioned. I measured the thickness in several places and avoided those ridges.
     
  10. David Mast

    David Mast New Member

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    Thanks LaLi.... Both are true. You don't stamp random shapes into the plate, you use them as features. But when you turn a 2 dimensional sheet into a 3 dimensional part, the rigidity increases dramatically. I'm just now seeing pictures of the "New" Allen Vang, that I didn't see before. It'd quite the improvement
    Thanks for the verification on the micro cleat. That helps me as a dimensional reference to photos.

    Another question if I may.......Is the groove in the primary sheave(the one feed from the fairlead) a standard half round or is it tapered? Even right on the swing axis, the feed angle changes a bit and it would seem a taper groove on a thicker sheave would be advantageous.
     
  11. David Mast

    David Mast New Member

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    Thanks Ed........... I think they used 18Ga on the swing arm because the forming around the pivot shaft would be a bitch with 16Ga
    Do they use a Alum. Micro Cleat or a Carbo?
    I think I'm getting close to going to Cad
     
  12. chemprof

    chemprof Member

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    That primary sheave is captured in a ca. 7.87 mm channel by those strengthening bends. The sheave groove looks to me to be a smooth radius or arc of a circle that would be maybe an inch in diameter. Does that make sense? The groove isn't tapered, and isn't a full half-round, it is much shallower.

    It is interesting how Harken buried that sheave so it looks like it wouldn't come out even if it's rivet were to break!
     
  13. chemprof

    chemprof Member

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    Oh, I forgot -- the cleat is carbo.
     
  14. David Mast

    David Mast New Member

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    Well that's another way to fix the problem I'm looking at. So the channel (side plate spacing) is 7.87mm or .309/.310" which is the Sheave width as well. And the groove is a shallow .5" radius(inch in diameter)?
     
  15. LaLi

    LaLi Active Member

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    Not necessarily. Harken changed it to aluminium a couple years ago, and you can buy either version now. The composite cleat has a blue fairlead and the aluminium cleat a red one.

    But why copy that if you can choose anything? What about a Spinlock, for example: PXR Cam Cleat - Cleats
     
  16. David Mast

    David Mast New Member

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    Wow.....PXR Cam Cleat....now that's slick. I'm totally becoming a Dinosoar. But then you knew that when I eluded that I use AutoCad :)
     

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