Heath Robinson spine tester

Si2

New member
I really needed a spine tester to evaluate my wooden arrows. So I built one up on Saturday out of bits that were lying around.

It's a bit on the rudimentary side, but it does work. I am going to modify it slightly to bring the pivot point, and hence the zero angle, down a bit. So the scale is not so canted up in the air.

It's made from a lump of 4x2, some brass rod and tube and a bit of 1/4" dowell. I used some lead wheels as a counter balance and a bag of metal toy soldiers as my 908gram mass, suspended by a bit of bent coathanger from the centre line.

I also had a go at creating my own scale, but eventually found the one pictured on the internet.









Regards
Si
 
D

Deleted member 7654

Guest
I recongnise those Dinky toy wheels!
Nice jig, it's one of the many things on my to do list.
Del
 

JohnnyH

New member
I love that you used metal toy soldiers as the weight :)

I wont pretend I know what it does, but it looks good.
 

Si2

New member
I really wanted to show that you can knock up something to test your arrows quite easily from odds and ends.

For the pivot you could quite easily use a nail and have the dowel pivoting directly on it with just a hole.

You don't even need a scale for comparative measurement. Just mark points on the wood - that would be enough to show if you had a rogue arrow.

I've made a few mods since those pics - I'll update them tonight with the de-luxe version.

Si
 

Si2

New member
more pics - I lowered the pivot point to make the zero position more horizontal. You can see the black dot above the new one that shows where the last one was...

First pic shows the arrow in place.



now with 908 gram load (of lead soldiers)


scale reading showing 28lbs.


Just realised that the picture shows the hook in the wrong place- it should be hanging on the centre line - under the point where the pivot touches.
Si
 

Si2

New member
mainly Ancients, but I play quite a few others.
Normally DBA, but again I play others - WM, WMA, BP, IABSM, Impetus, Bag the Hun.
Armies in 28mm and 10mm mostly.
I have a shop here - Bend Sinister
Si
 

Darren

New member
Hi, I've just started putting one of these together using scrap wood and bits and pieces.
I've used the scale that you linked to Si2
Couple of precision questions ?

1- when i print it off do I just keep it exactly to the scale it comes at.
2- the mention of length should be 40mm on the print out, wheres that - is it from the pivot point to where you have it touching the arrow ie where your lead wheels are ?
3- If my uprights are 26 inches apart do I want my pivot point dead centre- or do i set it to one side by 40mm
4- where exactly do i hang the weight - under the pivot point or under where the pivot bar contacts the arrow

And do a lot of those questions make that much difference ? :)

I've made a taper jig and spine tester in one, just need answers to the above before I finaly set it together, Oh and find a nice 2lb weight to use.

Thanks Darren.
 

Si2

New member
Darren
Ideally print out the scale so that the 40mm line is actually 40mm.
The pivot is offset 40mm from centre.
The weight hangs on the pin that rests on the arrow. my pin isnt strong enough to hold the weight so i hang it direct on the arrow a little bit infront of the pin.
I need to make a pointer arm strong enough to hold the weight.
So pivot is offset by the length of the 40mm line.

If you want a purely comparative measurement then you don't even need a scale, just a mark.
Then see how close the the pointer is to the mark.

Hth
si
 

Darren

New member
Cheers Si2, off work for 3 days after today so i'll get on and finish it.

I'm running out of arrows, sent 5 of this first lot I got with the bow to arrow heaven :(
 

Darren

New member
Managed to get a 2lb weigh, was looking for old scale weights off ebay etc but of all places to eventualy get hold of one was a fishing shop, called in and asked them if they have a 2lb weight, cheap ?

He happily weighed me out some large size shot to exactly 2lb "guy took it as a personal challenge to get it spot on" and charged me ?3, Bargain considering how small it looks and just for pure conveniencce being local..
 
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