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    Greasing the track

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    Basilisk120
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    Greasing the track

    Post by Basilisk120 on Sat Aug 21, 2010 9:03 pm

    First topic message reminder :

    Just thought I would throw this out to the group.

    Does anyone use anything to "lube" the bolt track? Use silicone on the track or a wax on the bolt to reduce friction? Or would such a thing wear off too quickly to actually help. Or worse attract dust and grit.




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    Regerald
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    Re: Greasing the track

    Post by Regerald on Sun Aug 29, 2010 12:47 pm

    basilisk120 wrote:

    So here is the math I was using. Maybe a case of me trying to be too clever.
    (Reginald just spelling it out so it obvious and I'll rember how I did it next time I read this topic)
    W= F * x (Work = force * Distance)
    W = .5*m*(v2^2 - v1^2) (Work = delta E or E2-E1)
    F= C *Fn (Force = friction coefficent * Normal Force )
    Fn = m*g (Normal Force = mass * gravity - assuming same assumtion about bolt being horizontal or close enough)
    so
    W=W
    C*m*g*x = .5*m*(v2^2-V1^2) were V1 is the intial velocity so it is 0 and masses cancel
    2*C*g*x=v2^2
    sqrt(2*C*g*x)=v2

    assuming C = .5 g =9.81m/s^s x=.3048m (1 foot) v2 = 1.73 m/s
    hence slowing by 1.73 m/s
    Yes, maths are correct. One think that I'd point at: putting V1 to be zero means that you have a crossbow that shoots bolt with a speed of 0 m/s (bolt stops at the end of a groove). After removing all the bolt friction (somehow), this same crossbow starts to shoot with a speed of 1.73 m/s. In other cases, we have to use V2 = sqrt(2*C*g*x + V1^2). If crossbow shoot, say, 30m/s with a friction (V1 = 30m/s) V2 would be 30.05m/s,
    and if V1 = 50m/s, V2 = 50.029.

    But, as Pavise wrote, bolt bends during it's acceleration, so it can be pushed against its groove with little more force than its own weight.. Still, somehow I think it's the least of my worries. String friction is much larger in any case..

    Why I am interesting in this subject: I made a wooden stock, and I'm (maybe) planning to put two stripes of metal along the sides of a bolt grove, and let grove itself remain wooden. (so only string friction will be reduced). Did anyone here do that?
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    Re: Greasing the track

    Post by Basilisk120 on Sun Aug 29, 2010 9:10 pm

    Thanks for the kind words on the math.
    Regerald wrote:
    Why I am interesting in this subject: I made a wooden stock, and I'm (maybe) planning to put two stripes of metal along the sides of a bolt grove, and let grove itself remain wooden. (so only string friction will be reduced). Did anyone here do that?
    How much of an effect that has would probably depend on the bow in question. If the string barely touches the base than wouldn't do to much. on that note that is one of the reason I am ordering that PTFE sticker. In my case reducing string friction would do quite a bit I believe. Well only one way to find out.

    Pavise-
    Thanks for the idea to get that patented Smile I will call them "Basilisk Super Speed Bows" with tag line "Shoots so fast it's measured in relativistic speed" Razz Rolling Eyes jocolor I'll give everyone here a discount of course Very Happy



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    Metal rub-rails

    Post by Geezer on Mon Aug 30, 2010 12:49 pm

    Somebody mentioned placing metal rub-rails alongside the bolt-groove. This was done years ago on the old Jayhawk crossbow kits. In their case, it was because Jayhawk knew the steel bowstring they provided with the kit would eat the track away in no time. Of course steel bowstrings are a terrible idea. They're strong allright, but inflexible, heavy, and they stretch. After a few hundred shots, your steel string no longer stays on the prod, but you can't afford to twist it for tightening, so they're useless.
    I would recommend, if you're willing to go to the trouble of putting a low-friction metal rub-rail on your crossbow, go ahead and carry it to the groove as well. That way, you'll get low friction for string AND bolts. It'll weigh a bit more, but in the scheme of things, that shouldn't matter too much.
    You'll also see metal rub-rails on the outer edges of the track, between prod and lock, but that's usually to reduce incidental wear from using a cocking-lever... mostly the gafa. Geezer.
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    Just ran out in the 97 degree heat

    Post by Moon on Mon Aug 30, 2010 2:47 pm

    with my chrono, Maximilian, a couple 590 grain 16" hunting arrows and a spray can of Jigaloo......yes Jigaloo. It's made in Canada and sold in Advance Auto stores. It's as slick as an eel's butt. I use it on modern crossbow deck rails to help prevent premature center serving failure. It dries with no sticky residue. On those crossbows it is useless for increasing arrow speed. I shot 5 arrows without the Jifgaloo on the deck and then wiped it down with the Jigaloo. It made the deck feel noticeably slicker to the touch but the chrono showed no increase in arrow speed, the same results I get with multiple modern crossbows. I never use grease, oil or wax (dirt collectors).
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    Re: Greasing the track

    Post by Basilisk120 on Tue Aug 31, 2010 10:01 pm

    So the PTFE film came in today. In a really large box for a such a small thing. But I am going to wait till next week to try anything since the Crown shoot is this weekend and doing massive rework before a shoot and no time to test seems like a less than optimal thing.




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    Regerald
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    Re: Greasing the track

    Post by Regerald on Wed Sep 01, 2010 4:26 am

    Moon wrote: It made the deck feel noticeably slicker to the touch but the chrono showed no increase in arrow speed, the same results I get with multiple modern crossbows.
    In a modern crossbow this problem doesn't exist: prod (or separate limbs) rises above the track level, and string is barely touching the track and doesn't generate much friction - so there is no need for greasing. With a "classic" crossbows, it's a different story..
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    Re: Greasing the track

    Post by Ivo on Sat Sep 04, 2010 10:40 pm

    The arrow/bolt speed is a very interesting question, I'm glad so many of you are heavily researching and diving into testing out your finds.

    I've been gathering bits of info regarding this issue from everywhere...My first serious encounter of such information was in the videos and website made available by our Dear departed Robin Allen.

    http://www.thecrossbowmansden.com/Hints_%26_Tips/Entries/2006/2/5_About_building_the_Prodd.html

    http://www.thecrossbowmansden.com/Hints_%26_Tips/Entries/2007/10/20_Track_Dimension.html


    [center]

    He mentions a hefty number of variables that effect the speed of "various crossbow components" that all add up to the the resulting arrow/bolt speed.


    I also spoke with Moon, Cossack, and other crossbow enthusiast who have
    tested many different crossbow configurations in their life and have come to this conclusion -
    there is no "single" factor that can dramatically increase the speed, it
    is the combination of factors working together.

    So we are talking milimeters...string material, string diameter, string serving material, string weight, prod design and it's efficiency, prod tip design, prod tip height, prod angle, track dimensions/design, track material/finish, arrow clip design, arrow clip material, arrow material, arrow diameter, arrow spine, arrow nock design, arrow nock material, arrow nock finish, fletching material/surface texture, fletching length/height, fletching offset, field-point/broad-head design/weight/center/alignment..etc...

    I'm sure the list can go on, but the main idea behind the list is that all these things interact - one thing changes...the rest of the system follows.

    So best of luck to all of you and most importantly - have fun researching...building...testing...discovering!

    Ivo






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    Re: Greasing the track

    Post by nirvana on Mon Sep 13, 2010 9:05 pm

    ~"~


    Last edited by Ivo on Sun Dec 19, 2010 9:24 pm; edited 1 time in total (Reason for editing : Spam)
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    Re: Greasing the track

    Post by nirvana on Fri Dec 17, 2010 3:51 am

    ~"~


    Last edited by Ivo on Sun Dec 19, 2010 9:25 pm; edited 1 time in total (Reason for editing : Spam)
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    ???

    Post by Moon on Fri Dec 17, 2010 8:36 am

    I'm not drinking so I can't blame my confusion on that, but the previous post????
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    Re: Greasing the track

    Post by Geezer on Fri Dec 17, 2010 8:43 am

    Moon: I don't blame you for being puzzled. It seems to be a new form of spam, designed to get past the filters. The point is to get you to open the two underlined words at the bottom. Kinda looks like a waste of time to me. No doubt Ivo will deal with it in time.
    Meanwhile, I'm back out to the crossbow shop, trying to get stuff delivered for Xmas. This is where the round belly and long white beard really pay for themselves. Geezer
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    Re: Greasing the track

    Post by Ivo on Sun Dec 19, 2010 9:28 pm

    Good Day Gents,

    Forumotion's tech team is doing updates about once a month which includes major fixes like spam filter updates as well as added forum functions...so... working on the issue and it's just a matter of time now. Smile

    Ivo




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