Home Made Spine Tester

[MaylandL]

Hello All

Thought I'd share with you my first attempt at making a spine tester based on the designs here on Ozbow.Net and suggestions from Archangel (thank you very much for your help). I was really surprised about how quickly it was to put together. All in all, it took about 3 hours to put the whole thing together from designing, measuring, cutting, predrilling holes and assembling.

Many thanks for the resources and information on this site. It sure has been a great help and a credit to all for contributing their knowledge and experience for others to use.

I am surprised and pleased about how it turned out. It wasn't that difficult and my handyman skills are dodgy at best. Tools (especially power tools) and I have at best a nodding acquaintance.

I think the longest part of the exercise was getting the supplies together. The total cost of materials was less than $30. The most expensive part was the MDF, and I have enough left over for other projects.

What I have to do now is to get the 2lbs weight sorted out and then I am good to go. I've bought some victorian ash/tassie oak dowel to try out as shafts. Having read prior posts on arrow shaft material it would seem to be ok for target/field archery. Anyway going to give them a go and I'll let you know how they fly. With the spine tester I'll be able to match the shafts.

Many thanks to my wife for the photos. My first attempt had too much light but my wife sorted that out for me.

Happy shotting all.

[archangel]

Maylands

Don't sell your handy skills short, the spine tester is a credit to you! I am looking forward to seeing your first set of arrows coming off the assembly line ready for the range in a week or so. This project really goes to show how sharing knowledge about building and using equipment helps toward building a good collective and sense of community.

PS. Were you able to download the conversation chart from Jim Hill's post on Lore & Legend? I can PM it to you or you can follow the link.

http://www.jamesmhill.com/Spine_Tester.html

David

[Mick Smith]

This is something I've had on the agenda for years. Just haven't managed to get around to it yet. I'm always just a little bit suss when I buy so-called spined shafts. With no way of checking them, you have just got to have confidence in the supplier. Course, you can sometimes tell there's something amiss when you try them out. Depends on the amount of centreshot on the bow I suppose. With your own spine tester all the doubt disappears.

How do you go measuring the amount of bend in the shaft against the steel ruler? I mean is it delicate enough to do a good job? Other spine testers I have seen have different ways of exagerating readings to make even slight differences obvious. If the old ruler trick works, I wouldn't bother with more elaborate methods.

Anyway, well done mate! Now I might have inspiration to have a go too.

Mick

[Hood]

Nice effort there MayLand, looks great to me to. So what if it's not all nice and pretty looking like the factory ones but hey it works and I bet it cost you a lot less then the other so now you have some money spare I say it's your shout for the next round of beer mate.

Mick

[archangel]

Mick (Smith)

Reading from the steel ruler takes a bit of practice. I found that the conversation chart posted on Jim Hill's thread (see below) was written in inches based on the unit 1" of deflection @ 26" = 1.000.

Thousandths of an inch are just a tad hard to read from a ruler so I converted his table to metric, rounded to the nearest 0.5mm. This was now a lot easier to read (depends how good your eyesight/glasses are).

Once you have the chart showing deflection in millimetres, you read across and find the matching spine measurement. I sight the unweighted shaft by eye to get a 'resting' base measurement, then lower the weight and record the difference from the ruler. It gives results within 2-2.5lbs, close enough for me, a lot damn closer than most archery suppliers can provide.

Quick and simple. I would be happy to send a JPG of the chart with metric conversion if anyone is interested.

David

[Stickbow Hunter]

Good job Maylands. Now you should be able to make a good matched set of arras.

Jeff

[Mick Smith]

Thanks mate. Yeah 2.5 lbs is pretty close. I was thinking of making one
with a dial gauge like the one on Jim Hill's post until I saw yours. Now I'll save myself some money and trouble and copy your spine tester. I've even got an old ruler already and some scrap timber lying around. All I need to do now is get motivated........

Mick

[tracker]

Hubris built one of these tester's 6 months ago. A great bit of gear. Made a big difference to our arrow shafts. It's VERY nice to have a matched set of arrows!

Mick.

[hubris]

For a second there I was about to go down to the shed to look and see where my one had gone!! heheheh

(I can't see whether you've done it or not, but I also added a sewing needle to the end of the bolt to help me get a more accurate reading against the ruler)

Yep... there's something cool about making your own REALLY cheap, and bypassing the corporate side of this hobby

Good on you mate!

[erron]

this is the essence of this site, you know?

Excellent job, Maylands, and thanks to you and your wife for posting the pics.

Must finish the Links forums, this reminds me

Erron

[MaylandL]

Hello Everyone

Thank you very much for the kind and generous words of encouragement.

To Mick Smith, have a go with it, and I can definitely say it wasn't that difficult or time consuming a project. All of the materials I got from Bunnings. Let me see if I can give a rough costing:

Eye bolts $2.50
Packet of Screws $2.50
Metal Bracket $2.50
Bolt, net and washers $2.00
Ruler $2.00
Double sided tape $2.00
MDF $17.00
TOTAL $30.50

Its a heck lot cheaper than the commerially available ones on the internet that range between $120AUD to $260AUD. It would be more if you include shipping and handling from the states.

And I still have left over stuff for other projects.

Archangel thank you for the link to the spine tester and the suggestions for the conversion but I managed to find the following link:

http://pages.cthome.net/dkelms/spine.htm

This link gives the formula for calculating the spine. Just change the scale of the distance of 26" to mm (660mm) since the deflection is now being measured in mm instead of inches.

Hubris, your idea about using a sewing needle is a good one and something I'll have to look into. Thank you for your suggestion.

To Mick, its a really good feeling to have made your own gear. I think it makes you appreciate using trad gear even more because you've made it yourself. Yeah, when I'm in Adelaide, my shout down at the pub

Next project is making jig for straightening arrow shafts.

Happy shooting all

[MaylandL]

Hello Everyone

I thought that I might just provide an update and a tip. Its worthwhile sorting out your 2lbs weight first before you mark out where all of the components go. It just helps with how the weights will be attached to the bolt (or other mechanism of suspending the weight from the shaft) and the spacing that's needed.

Its just something that's occurred to me because I have to sort out how best to hang the sinkers on the bolt given the washers I have are no where enough to make up the 2lbs.

Happy shooting everyone

[ole_silver]

hey thats great Maylands.........

good tip....... it has slowed me down, i have started mine with the
dial indicator off the ebay....

n forgot to think of the weight........

yes, archangel..........

i would love a copy of the metric conversion....... it will save my dwindling
brain cells..........

i have also followed the Glenn Newell, method of the grooved work bench and cutting 12 x 12 mm billits into my own arrows..... (good to have the grooved base plane.. ) and started to "barrel" the shapes........ bit tricky but good feeling fun n acheivements.

as stated......... all the tips have been accessable by the items listed in this forum....

thanks again.........
ole_silver
********* longbow 4 ever *********

[archangel]

ol_silver, sounds like you will be busy for a while!

For my results, I found 12mm square billets were just a little too big. Depends on what diameter shaft you looking for in the end. Another tip I have just tried for final finishing ... my mobile Workmate bench has adjustable wooden jaws with "V"- channelled edges.

I folded some wet and dry paper in between these, adjusted to the gap I wanted and cranked the end of the shaft into the drill. The workbench held the shaft really well, no burnt hands. I was also able to make fine adjustments to barrel the nock end.

Will forward the conversion chart via PM tomorrow.

[Wild Russian]

Hi all,
I'd like to build this device too, so my head is full of improvements...
We all have computers - yeah? So we all can make our own rulers - with pounds, kilograms or bottles of fire water
Or somebody who have Adobe Illustrator, Corel Draw etc. can make it for us - with zero point against the needle.
Next step - to print it on paper or clear film (it will be better to use film recorder, this laser printer powder haven't good adhesion to clear film in my opinion).
If you'll print the ruler on paper - glue it on any flat surface, but if it will be clear - use Lexan or some clear stuff and enjoy your shaft deflection
And last step is to make some adjustment base for the ruler to adjust zero and needle point
Any opinions?

Max

[erron]

Max,

just wondering if you took this any further?

Erron

[Wild Russian]

Sure.Just think about how to attach nuclear reactor or supercomputer to it.
I plan to make it (spinetester, not attachment ) this weekend. Was too busy at work and with my little dog hunters.

[erron]

Okay, I look forward to news!

Erron