LumberJocks

A Question of Balance. LJ Challenge-14

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Project by vipond33 posted 10-14-2012 09:06 PM 4421 views 22 times favorited 37 comments Add to Favorites Watch

I would have thought that the LJ community was very well balanced and happily true following the last contest, yet here we are again, gruesome death to all Politics & Religion notwithstanding. For the current contest is to once more build something that balances, and yet again with not even a T shirt for a prize; it’s just for fun. So what, I had to do it anyway (though I do covet that shirt).

My entry is an analog math balance beam (no batteries required, no digital readout in sight), a simple visual teaching aid for very young children that shows them the relation between numbers. With it, a teacher can easily demonstrate the concepts involved in ordinary (small number) addition, subtraction and multiplication, or have the students try by doing it themselves.

Steel washers on the left must equal (proportionately) steel washers on the right - or the beam goes tilt.
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This is an adaptation (and I am indebted to Jim Makowicki) of a project from his book Making Heirloom Toys.

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I did take some small liberties with the design and materials but stayed true to his overall plan.

My own build is with ebony veneer covering solid cherry, beveled throughout and with the tapered beam done in quartersawn stock to stay true. Cherry pegs marked with Letraset numbers (anyone remember?) complete it with a mixed bunch of polished brass fittings.

As usual, I wanted to make it a bit prettier than plan but I also had to build it somewhat sturdier too because it is for school use – that is to say by unknown pint sized assailants. Still, by design, it must always be a rather delicate piece so some supervision is required. The overbuild is mostly in the case for I could do little about the tremendous leverage possible in those arms.

Outside of the indicator to pivot block joint there is no glue in the assembly, just long screws in cups. Somewhere down the road it may have to be worked on by others so I left it so.

The pivot ball bearings riding on the brass axle are triple sealed, 3/4” x 5/16” class 5 type, rated to 25,000 rpm. A bit overkill maybe? but Grade1 kids can really get going sometimes you know.

To preserve it and store in the supply room I made a fitted BB plywood case with inlaid solid hickory edges, leather padded retainers and a small interior cherry box to hold the washers.

Detail showing how the main pivot block is adjustable for that critical centre distance and showing the overall balance adjustment bar mount.

It is interesting to note that any variations in weight of the components are of no account in this type of device as you may easily correct errors with the sliding adjuster. What can never be corrected for are the distances between the weight points (posts) so there was a whole lot of very careful layout and drilling involved.

Even still, with minute differences in weight, slop on the posts and inertia friction in the bearings the indicator will often not point perfectly to the true north strong and free. Canadian made, eh?

A locking pin on a keeper wire holds the beam steady while you or the students add weights. Pull it out to find if your answer is correct! Anti slip material covers the base and rubber O-rings sit at the bottom of each post to allow you to get your fingertips around the lowest washer. Steel glides are nailed on 4 box sides.

When finishing up, what was amusing to me was that the very last operation on the build was to attach the carrying handle to the case with the beam inside – not at dead centre of course but at the combined balance point.

This will be a lasting (hopefully) contribution to my daughter’s small school as I’m not very good at baking.

Shellac followed by pre-cat lacquer.

37” x 7” x 5 1/2” Beam
39” x 8 1/2” x 7” Box
About 38 hrs.
Build on LJ’s.
gene

Only 4 entries in the challenge so far, so let’s see many many more (and all the previous contestants for sure!). I’ll arm wrestle anybody for the t-shirt if there ever is one.

-- gene@toronto.ontario.canada : dovetail free since '53, critiques always welcome.





37 comments so far

View RussInMichigan's profile

RussInMichigan

478 posts in 1447 days


#1 posted 10-14-2012 09:27 PM

vipond33,
I’m awed and amazed. It is a work of art, a masterfully executed woodworking project, and as you mentioned will be a durable legacy to some children’s learning experience.

Thank you very much.

View kiefer's profile

kiefer

3118 posts in 1333 days


#2 posted 10-14-2012 09:32 PM

What a beautifully made teaching aid and certainly got balance .
Math is logic and this visual approach should go a long way in understanding math .
I think we have to start a fund for your t shirt , you deserve one for this kind of effort .

-- Kiefer 松

View TopamaxSurvivor's profile

TopamaxSurvivor

14797 posts in 2342 days


#3 posted 10-14-2012 09:35 PM

Awesome. That should inspire many young minds!

-- "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

View patron's profile

patron

13064 posts in 2007 days


#4 posted 10-14-2012 09:57 PM

not just teaching math

but art as well
this is amazing work

maybe a baking aid
for your next one

you have my vote for a shirt

-- david - only thru kindness can this world be whole . If we don't succeed we run the risk of failure. Dan Quayle

View rance's profile

rance

4135 posts in 1827 days


#5 posted 10-14-2012 10:00 PM

I really like your techniques Gene. Particularly the veneer with the beveled edges. I may have to try that one. With HHG of course. :) Thanks for sharing your projects.

-- Backer boards, stop blocks, build oversized, and never buy a hand plane--

View shipwright's profile (online now)

shipwright

5008 posts in 1464 days


#6 posted 10-14-2012 11:11 PM

Wow Gene !!!!!!!!!!!!!

Am I ever glad I didn’t have time to build the upside down mobile I was planning. (really)

Your projects are always so perfect but this is over the top.

Your daughter and her friends could use it for a teeter -totter (sp?) or a catapult for laying siege to the staff room with the washers as projectiles and the fat kid in grade three as the launch force…. and the box could be a panic room for the class turtle.

On balance, you have my vote.

One small critique: Plain steel washers??? What were you thinking? Silicon bronze would be lovely … or gold!

Kidding aside, Amazing again Gene.

-- Paul M ..............If God wanted us to have fiberglass boats he would have given us fiberglass trees. http://prmdesigns.com/

View ShaneA's profile

ShaneA

5313 posts in 1265 days


#7 posted 10-15-2012 12:27 AM

Impressive Gene, I have come to expect great things from you, and you do not disappoint. This is an engineering miracle, in my world.

View JL7's profile

JL7

7222 posts in 1631 days


#8 posted 10-15-2012 12:27 AM

Very cool Gene – Another masterpiece in wood. What a great adaptation….

-- Jeff - I have not failed. I've just found 10,002 ways that won't work.

View peteg's profile

peteg

2906 posts in 1489 days


#9 posted 10-15-2012 12:36 AM

Gene, another #$%^&*() super fantastic piece of work :)
Pete

-- Pete G: If you always do what you always did you'll always get what you always got

View ChuckV's profile (online now)

ChuckV

2427 posts in 2194 days


#10 posted 10-15-2012 12:46 AM

Gene,

This is completely off the charts! What an amazing design and build. I just love what you have created.

-- “That it will never come again / Is what makes life so sweet. ” ― Emily Dickinson

View gfadvm's profile

gfadvm

10987 posts in 1356 days


#11 posted 10-15-2012 12:56 AM

That is an absolutely amazing educational toy. But this one should go to a museum of fine art and a pine replica to the school. Send this man a T shirt!

-- " I'll try to be nicer, if you'll try to be smarter" gfadvm

View LittlePaw's profile

LittlePaw

1571 posts in 1745 days


#12 posted 10-15-2012 01:13 AM

That’s a winner, Gene!

-- LittlePAW - The sweetest sound in my shop, next to Mozart, is what a hand plane makes slicing a ribbon.

View Birks's profile

Birks

109 posts in 895 days


#13 posted 10-15-2012 02:03 AM

All I can say is you deserve a damn T shirt if any of us do…
As a further challenge to this amazing project, make an analytical beam-style balance out of wood…. this would be absolutely amazing to me and from what I can tell, probably doable by the likes/skill of you.
Birks

PS: If you can make things like this, please don’t bake cookies for the school….

View Puupaja's profile

Puupaja

310 posts in 1767 days


#14 posted 10-15-2012 02:13 AM

This is great much more pedagocig than any other todays fine techology… every parents should have this instead of ipad…

-- http://www.facebook.com/pages/Puupaja/357028681017482

View gbear's profile

gbear

393 posts in 2766 days


#15 posted 10-15-2012 03:00 AM

That is sooooo cool! I want it just to sit on my desk so I can admire it and people can ask about it.
What a neat project…I think LJ should give you t-shirts in every color!!!

-- gbear, Carmichael, CA

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