The Arbalist Guild

Would you like to react to this message? Create an account in a few clicks or log in to continue.

Crossbows - Everything about Building, Modding, and Using your Crossbow Gear

Latest topics

» fix bolts
by chaz Yesterday at 2:27 pm

» Collotiere a Charavines crossbow
by stuckinthemud1 Thu Nov 19, 2020 1:00 pm

» New Build for 2020
by c sitas Tue Nov 17, 2020 5:47 pm

» how to Build a non Chinese repeating crossbow?
by c sitas Tue Nov 17, 2020 1:05 pm

» Fascinating reconstruction
by drawknife Sat Oct 24, 2020 3:54 am

» Cutting delrin straight by hand?
by drawknife Sun Sep 20, 2020 8:09 am

» Anyone make their own bolts?
by sydney1942 Wed Sep 02, 2020 3:03 pm

» Cocking via moving the bow.
by ora8i Fri Aug 28, 2020 2:03 pm

» Claw crossbow prototype
by Phil Abrahams Fri Aug 28, 2020 9:20 am

» Stirrups, how heavy? Design help needed
by stuckinthemud1 Tue Aug 18, 2020 2:24 pm

» ash lath and pin-lock crossbow
by stuckinthemud1 Tue Aug 11, 2020 2:31 pm

» Finish on lashings
by stuckinthemud1 Wed Aug 05, 2020 1:48 pm

» Look what the smith sent
by stuckinthemud1 Fri Jul 31, 2020 1:35 pm

» Covid 19 and crossbow builders
by kenh Thu Jul 30, 2020 10:22 am

» Crossbow accuracy
by Geezer Thu Jul 30, 2020 7:51 am

» How do you feel about miniature crossbows?
by El Zurdo Wed Jul 29, 2020 7:21 am

» Just finished my windlass crossbow!
by Dennis Greenaway Tue Jul 28, 2020 4:01 pm

» Sinew backed crossbow prod tillering. Update and questions.
by stuckinthemud1 Tue Jul 28, 2020 2:43 am

» snakeskin not birch bark on composite bows in medieval period
by Cornerstone Mon Jul 27, 2020 3:50 pm

» two axle mechanism makers/accurate plans?
by stuckinthemud1 Wed Jul 22, 2020 10:34 am

» Stonebow Buildalong
by banuvatt Thu Jun 25, 2020 9:00 pm

» How to Attach a PVC Prod to a Stock?
by banuvatt Tue Jun 02, 2020 8:22 am

» finally started my first composite bow
by stuckinthemud1 Fri May 29, 2020 12:40 am

» AMAZING MINI CROSSBOW code name KillCovid-19
by El Zurdo Thu May 21, 2020 3:14 am

» Draw length ash lath
by banuvatt Thu Apr 23, 2020 9:47 am


    Cheap and easy scales for measuring high draw weights?

    Riot
    Riot
    Fresh Blood

    Doesn't mean
    I'm new to crossbows


    Fresh Blood Doesn't meanI'm new to crossbows

    Posts : 8
    Join date : 2010-07-11
    Age : 44
    Location : Perth, Western Australia

    Cheap and easy scales for measuring high draw weights? Empty Cheap and easy scales for measuring high draw weights?

    Post by Riot on Wed Aug 04, 2010 9:18 am

    Hi all,

    Does anyone have cheap and easy ideas for weighing Rather high draw weights? by which im talking 300lb plus. Cheap and easy scales for measuring high draw weights? Icon_redface

    Ive recently cut out two potential prods from trailer leaf springs into different profiles, yet, they are so heavy in draw weight that i can not get an easy and accurate answer as what numbers im lookng at at what distances. I know the prods as they curently exist is far far far to heavy to be practical yet I would like the data so that i can use it help me plan/plot and make further changes (got to love R&D) Cheap and easy scales for measuring high draw weights? Icon_smile

    My old fishing scales are only good for 30kg and even after running it through a four fall sheaf block assemble im struggling to get it accurate enough at varying distance over 10cm due to the complex web of ropes.

    Cheers
    Riot
    Pavise
    Pavise
    Dear Friend, You will be Greatly Missed.
    Dear Friend, You will be Greatly Missed.

    Posts : 128
    Join date : 2010-02-07

    Cheap and easy scales for measuring high draw weights? Empty Re: Cheap and easy scales for measuring high draw weights?

    Post by Pavise on Wed Aug 04, 2010 10:30 am

    Suspend your prod securely and then by using a string or wire overly strong enough, hang known weights from this until you reach your desired draw length. Individual pieces of metal, bricks, etc., can be weighed individually and then tallied up. A marked stick will allow you to see and reference the progress. Wrap the prod well with duct tape and drape it with an old blanket when doing this to help arrest it should anything go wrong! Bathroom scales may also be utilized for the job too, but require a more sophisticated setup. And keep your body parts away from danger as much as possible!

    Hope this helps.

    Pavise
    Regerald
    Regerald
    Master Crossbowyer
    Master Crossbowyer

    Posts : 67
    Join date : 2009-11-30
    Age : 35
    Location : Finland

    Cheap and easy scales for measuring high draw weights? Empty Re: Cheap and easy scales for measuring high draw weights?

    Post by Regerald on Wed Aug 04, 2010 1:42 pm

    You can also make a device somehow similar to a windlass: just a couple of pulleys and a robe with a scale.
    Cheap and easy scales for measuring high draw weights? Lock11
    Also using double-pulleys can reduce weight to 1/5.
    Pulleys are better to be with a ball-bearing, otherwise static friction will affect measurements(but not very much)..
    Ivo
    Ivo
    Admin
    Admin

    Posts : 1041
    Join date : 2009-11-25
    Age : 32
    Location : NJ, USA

    Cheap and easy scales for measuring high draw weights? Empty Re: Cheap and easy scales for measuring high draw weights?

    Post by Ivo on Thu Aug 05, 2010 2:45 am

    You mentioned a sheave block with four sheaves? I thought they didn't make them with more that three sheaves...any way...as Regerald mentioned - friction can be an issue...why not try less pulleys in combination with Pavise's brick idea.

    There is also this one other way which may have been used back in the day to repeatedly span crossbows for a whole squad of crossbowmen(had an illustration somewhere...can't find it at the moment)...it's basically a lever only in our situation> lever with the scale attached to the longer lever arm....
    Spoiler:

    The Lever
    The lever is about the simplest of machines, one we're used to
    dealing with every day, from can openers to car jacks and millions of
    other everyday devices. A lever is used to change the direction of a
    force, and to apply Every lever has a fulcrum point, about which
    the lever pivots. The two arms of a lever are not equal. A lever lets
    you move a heavy weight with a small force, by taking advantage of this
    inequality. By applying half the force on the longer side of the lever,
    but moving it twice as far, we move the weight on the short side of the
    lever. In the lever below, we can move a 1 kilogram weight half a meter
    by putting a half kilogram weight on the long arm of the lever, and
    letting it push down one meter:

    Cheap and easy scales for measuring high draw weights? Lever


    The ratio of the long arm to the short arm tells us the mechanical advantage
    of the lever, which is the ratio of work put into the system to work
    done. If the long arm is twice as long as the short arm, the ratio is
    2:1, and the mechanical advantage is 2. So we could move the weight with
    half the force needed if we're willing to move our force twice as far.
    This comes in handy when you've got a motor that can apply only so much
    force.

    ...it's simple o-right, but In my opinion it's the most
    dangerous one of all since it's technically a catapult that can snap
    right back at you if something goes wrong.
    Cheap and easy scales for measuring high draw weights? 118282 ...if you do proceed, please do so with great caution.



    Cheap and easy scales for measuring high draw weights? Untitled
    * *
    ~ "I don't have any special talents. I'm only passionately curious."
    * * *
    ~ "All Genius is Simple"
    * *
    Pavise
    Pavise
    Dear Friend, You will be Greatly Missed.
    Dear Friend, You will be Greatly Missed.

    Posts : 128
    Join date : 2010-02-07

    Cheap and easy scales for measuring high draw weights? Empty Re: Cheap and easy scales for measuring high draw weights?

    Post by Pavise on Thu Aug 05, 2010 10:09 am

    "...it's simple o-right, but In my opinion it's the most
    dangerous one of all since it's technically a catapult that can snap
    right back at you if something goes wrong.
    ...if you do proceed, please do so with great caution."

    This is precisely why I suggested differently. Use the KISS principal and be aware of stored energy that can escape and maim you!

    Pavise


    Basilisk120
    Basilisk120
    Moderator
    Moderator

    Posts : 548
    Join date : 2010-03-01
    Age : 41
    Location : Arizona

    Cheap and easy scales for measuring high draw weights? Empty Re: Cheap and easy scales for measuring high draw weights?

    Post by Basilisk120 on Thu Aug 05, 2010 5:35 pm

    Is your issue with getting a decent weight measurement or getting a decent distance measurment?



    Something Something Dark Side
    Riot
    Riot
    Fresh Blood

    Doesn't mean
    I'm new to crossbows


    Fresh Blood Doesn't meanI'm new to crossbows

    Posts : 8
    Join date : 2010-07-11
    Age : 44
    Location : Perth, Western Australia

    Cheap and easy scales for measuring high draw weights? Empty Ah, i see....

    Post by Riot on Fri Aug 06, 2010 4:59 am

    Cheers for the pic Regerald :-) I do believe I was using the sheave block wrong Cheap and easy scales for measuring high draw weights? Icon_redface (far to embaressed to say how lol). I shall give it another attempt on the upcoming weekend.

    And thanks to Pavise as well, the blanket idea sounds rather easy and nifty, so ill put one in place, i'll even contemplate mounting a small bar over the top of the tillering board for some added peace of mind.


    Im currently looking for draw weights at a an 8" (20cm) draw length, being new to steel bow making ive assumed that shorter draws = lower poundages and less forces being forced into the leaf spring....from a safety and newbi perspective. Although, i am tempted to try the draw length out at 30cm (especially ifi end up cutting to much steel out of it, arrived at the 30cm draw by simply halving the bow length as you would when making a regular archery flatbow)

    Cheers again
    Riot


    Last edited by Riot on Fri Aug 06, 2010 5:04 am; edited 1 time in total (Reason for editing : My very poor grammer)

    Sponsored content

    Cheap and easy scales for measuring high draw weights? Empty Re: Cheap and easy scales for measuring high draw weights?

    Post by Sponsored content


      Current date/time is Sun Nov 29, 2020 2:57 pm