Reman
Member
- Messages
- 250
- Location
- Bristol, UK.
I've toyed with the idea of having a go at making a variable speed pulley setup for my lathe for a while, but kept getting stuck on how to couple the two halves of the split pulley in a simple and reliable way.
Today I've been chatting to someone online who has a pillar drill that uses a variable pulley setup and he explained that the "Floating" half of the split pulley isn't actually coupled to the fixed half. This has got me thinking again about how I could do this...... And just to illustrate what I'm talking about, I've turned my VERY amateur hand to a spot of 3D rendering.
I'm quite pleased with how that turned out (Considering that the closest I've got to CAD software before was MS Paint !!! ).
OK, Now you can probably see roughly what I'm thinking (Nothings to scale BTW). The idea is that "C" can slide and spin freely on the shaft ("E"), "D" is on bearings that are locationaly fixed to the shaft. It's one half of the output pulley and the input pully machined from one piece of metal, "A" is a cup type affair with a hole in the end so a bolt can be screwed through it and into the end of the shaft to wind "A" along the shaft and push "C" towards "D" (Via a needle roller thrust bearing. "C" is completely freewheeling and doesn't help with transferring torque. It's just there to push the drive belt up to the desired position on "D". I think that should explain the basic idea.
On the other end of the belt there would be either a normal pulley and a tensioning idler, Or a similar setup to the above, But with "D" attached directly to the shaft, and a spring replacing "A". Either way should be able to take out the slack and keep the belt tight enough.
The benefits of having it all running on a stationery shaft would be that I could adjust the speed on the fly without having to stop the lathe.
......... So what am I missing? Why won't this work? Anyone got any better ideas that would be equally easy to make on an old/small lathe?
Generally, this is a "Wouldn't it be cool to make this work" kind of project idea rather than the "Simplest route to variable spindle speeds", So don't start screaming "VFD the damn thing!!!" all at once please.
Today I've been chatting to someone online who has a pillar drill that uses a variable pulley setup and he explained that the "Floating" half of the split pulley isn't actually coupled to the fixed half. This has got me thinking again about how I could do this...... And just to illustrate what I'm talking about, I've turned my VERY amateur hand to a spot of 3D rendering.
I'm quite pleased with how that turned out (Considering that the closest I've got to CAD software before was MS Paint !!! ).
OK, Now you can probably see roughly what I'm thinking (Nothings to scale BTW). The idea is that "C" can slide and spin freely on the shaft ("E"), "D" is on bearings that are locationaly fixed to the shaft. It's one half of the output pulley and the input pully machined from one piece of metal, "A" is a cup type affair with a hole in the end so a bolt can be screwed through it and into the end of the shaft to wind "A" along the shaft and push "C" towards "D" (Via a needle roller thrust bearing. "C" is completely freewheeling and doesn't help with transferring torque. It's just there to push the drive belt up to the desired position on "D". I think that should explain the basic idea.
On the other end of the belt there would be either a normal pulley and a tensioning idler, Or a similar setup to the above, But with "D" attached directly to the shaft, and a spring replacing "A". Either way should be able to take out the slack and keep the belt tight enough.
The benefits of having it all running on a stationery shaft would be that I could adjust the speed on the fly without having to stop the lathe.
......... So what am I missing? Why won't this work? Anyone got any better ideas that would be equally easy to make on an old/small lathe?
Generally, this is a "Wouldn't it be cool to make this work" kind of project idea rather than the "Simplest route to variable spindle speeds", So don't start screaming "VFD the damn thing!!!" all at once please.
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