Why Isn't The Feed On Manual Lathes Servo Controlled?

derf said:
Manual machines are just that...manual. It's way simpler to keep things mechanical. When you start adding electronics things get complex and more expensive, not to mention harder to maintain.
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I have to agree, I've seen a lot of home shop machines over the year, and clean and well maintained are not words I would use to describe a lot of them.
 
There is a lot of interesting discussion on this subject. Here's my two cents. I suspect that it comes down to simple economics. The tooling and production lines for all the mechanical parts needed to build a manual lathe are already in place and have been for decades, so not only do you have economy of scale, you are way down on the learning curve. As for comments that you could get a CNC lathe for just a little more, I don't think so. For an ELS equipped lathe, you have no need for a complex control system or precision ground ballscrews. Because it is still a manual lathe and will be used like one, you don't need production items like bar feeders, automatic tool changes and swarf conveyors. You would use the lathe just like a manual lathe, except the change gears or QCGB would be replaced with a motor (servo or stepper) and a simple controller. If you took a commercially available mid to high end lathe, redesigned it to have an ESL and were able to sell it, it would eventually be as cheap as a geared leadscrew manual lathe with a QCGB, I think. The problem would be you would have to take a loss on the initial ones (as they would be much more expensive than a geared lathe) and it would be quite a risk that they would ever catch on. If they didn't you would lose a mint. And at the lowest end of the hobby spectrum, the Chinese mini lathe, I don't see how you could replace a handful of plastic change gears with an ELS and not have a significant rise in cost.
 
cjtoombs said:
There is a lot of interesting discussion on this subject. Here's my two cents. I suspect that it comes down to simple economics. The tooling and production lines for all the mechanical parts needed to build a manual lathe are already in place and have been for decades, so not only do you have economy of scale, you are way down on the learning curve. As for comments that you could get a CNC lathe for just a little more, I don't think so. For an ELS equipped lathe, you have no need for a complex control system or precision ground ballscrews. Because it is still a manual lathe and will be used like one, you don't need production items like bar feeders, automatic tool changes and swarf conveyors. You would use the lathe just like a manual lathe, except the change gears or QCGB would be replaced with a motor (servo or stepper) and a simple controller. If you took a commercially available mid to high end lathe, redesigned it to have an ESL and were able to sell it, it would eventually be as cheap as a geared leadscrew manual lathe with a QCGB, I think. The problem would be you would have to take a loss on the initial ones (as they would be much more expensive than a geared lathe) and it would be quite a risk that they would ever catch on. If they didn't you would lose a mint. And at the lowest end of the hobby spectrum, the Chinese mini lathe, I don't see how you could replace a handful of plastic change gears with an ELS and not have a significant rise in cost.
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These machines exist, a perfect example of one that I run 3-4 days per week is the Bridgrport EZ Path lathes built by Romi with Bridgeport controls. Servo driven ball screws and a C axis encoder, they have hand wheels which are connected to the X & Y axes by encoders and may be ran as an almost manual lathe with little data input.
They were designed as a bridge (no pun intended) between manual lathes and turning centers, the control is conversational and easily programmed without knoweledge of G Code. The machine in this link is exactly the same as the 2 that we have where I currently work, one made in 1995 and the other in 1994. They are pretty much bulletproof.
http://www.sterlingmachinery.com/9561/Bridgeport+Ez+Path/
 
Wreck™Wreck said:
These machines exist, a perfect example of one that I run 3-4 days per week is the Bridgrport EZ Path lathes built by Romi with Bridgeport controls. Servo driven ball screws and a C axis encoder, they have hand wheels which are connected to the X & Y axes by encoders and may be ran as an almost manual lathe with little data input.
They were designed as a bridge (no pun intended) between manual lathes and turning centers, the control is conversational and easily programmed without knoweledge of G Code. The machine in this link is exactly the same as the 2 that we have where I currently work, one made in 1995 and the other in 1994. They are pretty much bulletproof.
http://www.sterlingmachinery.com/9561/Bridgeport+Ez+Path/
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The EZ path seems to me more of a CNC lathe with handles. What I'm talking about is just replacing the change gears or QCGB with a motor, so the only programing is the relative speed of the motor to the speed of the spindle. It would only be useable as a manual lathe (it wouldn't automaticaly cut threads, for instance). A much simpler prospect than the EZ path, but the only thing you gain is infinite threads/pithes and ease of setup, not any type of automatic machining.
 
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