An Irish Plumbob

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Joined
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Skibbereen, West Cork
Not an engine, just a complete timewaster!

What do you do with a 4" ring of cored bronze and a couple of slices of 3" aluminium? Most would think of a composite flywheel no doubt, so I had to be different.



Adding a bit of 1/8" brass wire, some 5/16" brass hex, a couple of 7/32" bronze balls and a couple of secret ingredients and this is what I ended up with. What does it do? Baffles the locals. I take great delight in telling them that Sir Isaac Newton never visited Ireland so gravity doesn't work the same here as in the rest of the world.



I did not consider doing a 'build' article, but a couple of procedures used along the way may help someone.

First cutting the ali slices from a length of bar. I use Armstrong's patent method, not having a power hacksaw. A good way to mark out the bar for cutting is with some masking tape as shown. A straight line with the masking tape is easy to accomplish.



To reduce the sawing load and to help making a straight cut, start off cutting level for the depth of the hacksaw blade



Then, start sawing uphill for the depth of the blade, like so



When this point is reached, start sawing downhill to the rear



Ditto repeato all the way through and a reasonably straight cut will ensue.

I put a bronze ball on the end of the wire to give it a finished appearance. Drilling bronze balls is best done in a simple jig, rather than just holding them in a chuck. I am sure there are other methods, but this is how I did it.

A length of scrap steel is drilled right through at the correct hole diameter. The cap should be made first. Put a small countersink on the face and machine off a small step that will locate the cap in the body.


Apologies for the poor photo.
The cap is parted off and the body made. A recess is put in the body to accept the cap. A hole the same diameter as the ball is drilled down so that when the cap is in place, the ball is lightly nipped.



Next three screws to hold the cap securely. I used my toolpost drilling attachment and headstock dividing device to drill and tap the holes.



Put the ball in the hole and push the cap on to test the nip. The ball will no doubt be a bit tight so a long thin wire will push the ball out from the rear.



Screw up the cap and drill into the ball for the required depth and that's all there is to it.

Now let's carry on with an engine!





 

Baffles the locals ? It baffles me too ! Care to post a vid ?

Geez - last time I sawed through a 3" bar I was an apprentice - punishment for some infraction or the other.

Ever since I consider hacksawing large stock "punishment".

Well done nonetheless.

Ken
 
The secret ingredients - don't tell anyone - are two magnets with like poles together! I milled out a hole between the two pieces of ali for one magnet so that even if the base was turned upside down, there was no trace of the magnet. The other magnet is in the bob weight.

Give the weight a push and it 'bobs' around for half a minute or so, before coming to rest as you see it.

Dave
The Emerald Isle
 
Dang, and I voted for flywheel..... :big:

Neat little gadget Dave! Good work!

Cheers

Jeff
 
Now let's carry on with an engine!

With talent like that you could design your own power hacksaw ;D
 

My Dad used to make these for us from the brown stuff. Back then we didn't have, or thought to use, rare earth magnets.

Nice job, thanks for the metallic inspiration!

 
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