Fulcrum for Compound Machines? General Discussion about useful equipment as well.

[LackJeff]

What can I use as a fulcrum for my compound machine? I was thinking perhaps a door hinge. Any other information that pertains to machines that you wish to share I would be more than glad to hear. I still have to order my wood and practically all the parts for my team's machine; if anyone has any good experiences with particular woods or other parts that would be godsend.

[salmonboi]

I used flanged ball bearings as my fulcrums for my compound levers. I drilled through a piece of aluminum and inserted the ball bearing into the hole. A dowel is then inserted through the ball bearing, which is attached to a vertical beam.

[LackJeff]

I used flanged ball bearings as my fulcrums for my compound levers. I drilled through a piece of aluminum and inserted the ball bearing into the hole. A dowel is then inserted through the ball bearing, which is attached to a vertical beam.

Thanks for replying. This makes a lot of sense; I'll give this a shot. Do you have any idea what I could use for the wood for the vertical beams and then the base that the beams would be install onto? I have to order the parts from Amazon ASAP, and I can't find any wood that would work as the beams. I'm not sure if I'm not using the write keyword, but all I can find are boards that are good for perhaps a base but seem too thin to be beams.

[LackJeff]

I used flanged ball bearings as my fulcrums for my compound levers. I drilled through a piece of aluminum and inserted the ball bearing into the hole. A dowel is then inserted through the ball bearing, which is attached to a vertical beam.

https://www.amazon.com/Basswood-Carving ... 42&sr=8-35

Found these for beams. Would they work?

[salmonboi]

For the base, I used a 2x4 which can be bought from Home Depot. The vertical beams I used was pinewood which can also be bought from Home Depot. I wouldn’t buy wood from Amazon as the quality of the wood is uncertain and can vary.

[sciolymachine]

Can someone please explain how to make it so the fulcrum fits perfectly with the beams? Like did you guys just use a drill and drill the same size screw into the beams and use that as the fulcrum? Or was there a hole drilled and a dowel was used as the fulcrum? And if so how would you find the perfect size? Thanks

[salmonboi]

was there a hole drilled and a dowel was used as the fulcrum?

I used a ball bearing with a outer diameter of 1-1/8” and an inner diameter of 3/8”. The hole that was drilled through the beam was drilled by a 1-1/8” Forster bit. This would allow the bearing to fit perfectly into the beam.

Because the inner diameter of the ball bearing was 3/8”, I used a dowel that was 3/8” in diameter and placed it through the ball bearing, and the dowel is connected to the vertical beam.

[CPScienceDude]

Mine is just a bolt. The lever arm has a 3/16 hole drilled in it and the bolt is 1/4. Getting around 29/30 on ratio scores in practice

[drcubbin]

Can someone please explain how to make it so the fulcrum fits perfectly with the beams? Like did you guys just use a drill and drill the same size screw into the beams and use that as the fulcrum? Or was there a hole drilled and a dowel was used as the fulcrum? And if so how would you find the perfect size? Thanks

If you have access to a drill press, that is the way to go. Keeps the hole for the fulcrum level.

[CrazyScaryMangoEater]

What can I use as a fulcrum for my compound machine? I was thinking perhaps a door hinge. Any other information that pertains to machines that you wish to share I would be more than glad to hear. I still have to order my wood and practically all the parts for my team's machine; if anyone has any good experiences with particular woods or other parts that would be godsend.

I find that PVC pipes work pretty well.