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Considering slant bed lathe build with hydraulic rotary spindles

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Uguessedit

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Initially the thought was convert the 13x37 and in fact I probably will follow through with a basic 2 axis conversion however I want something more intricate and think building from scratch is going to be the way to go about it. The plan is to build a turn center that utilizes a 8 tool turret and live tooling with hydraulic rotary spindles. The discussion here is there isn’t a lot of information regarding these spindles and what is needed to interface them to a motion control. The options available are endless from hydraulic love tooling, radial/axial milling, sub spindle, and so on. I suspect any motion control with appropriate axis count will suit its those components in between. Many of these hydraulic spindles have decent rpm ranges up to 6500 which is adequate and fairly compact while providing a vast amount of torque as well holding power when c axis machining is necessary. It seems it is the prime way to build a turn center where space constraints may be issue and a way to alleviate additional components that if need of I wanted to attempt retrofitting an existing manual lathe into. Turn center. Does anyone here have experience with hydraulics or knowledge of the control systems needed to implement such a design? Would one primary hydraulic pump be sufficient to supply multiple spindles? I am unfamiliar with the math necessary to factor pump size, etc... hoping someone here can point me to some literature or previous experience or better yet a diagram and basic list of components that would drive a system like this. I suspect the manufacturer can help to some degree although overseas in china and a language barrier it could take months to get the response or help if any would ever occur. I’ve already been waiting a week for a couple basic questions I had so I’d rathet not be left defendant. Searching Google “My Friend” I didn’t find much for any diy projects or where manufacturers had interest in explaining the gritty details about their operations or techniques. The technology having been around 100 years you’d think there would be more information available out there.
 

JimDawson

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Once you see the prices of servo controlled hydraulic systems you may change your mind. You can accomplish the same thing at a fraction of the cost using electric servos, and they don't leak hydraulic oil all over the floor. :)

But you control a hydraulic motor just like you control an electric servo motor, normally +/- 10V analog control with encoder feedback.

Yes, you can use a central pump and valve off to the individual systems. The heart of the system would be the variable displacement pump, then the various servo valves to operate the axes and spindle. Also add check valves, pressure reducing valves, pressure relief valves, directional valves, and flow controls as needed.

Formula: HP = PSI * GPM / 1714
PSI is gauge pressure in pounds per square inch; GPM is oil flow in gallons per minutes.

Rules-Of-Thumb:
Horsepower for driving a pump: For every 1 HP of drive, the equivalent of 1 GPM @ 1500 PSI can be produced.
Horsepower for idling a pump: To idle a pump when it is unloaded will require about 5% of its full rated horsepower
 
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Uguessedit

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Once you see the prices of servo controlled hydraulic systems you may change your mind. You can accomplish the same thing at a fraction of the cost using electric servos, and they don't leak hydraulic oil all over the floor. :)

But you control a hydraulic motor just like you control an electric servo motor, normally +/- 10V analog control with encoder feedback.

Yes, you can use a central pump and valve off to the individual systems. The heart of the system would be the variable displacement pump, then the various servo valves to operate the axes and spindle. Also add check valves, pressure reducing valves, pressure relief valves, directional valves, and flow controls as needed.

Formula: HP = PSI * GPM / 1714
PSI is gauge pressure in pounds per square inch; GPM is oil flow in gallons per minutes.

Rules-Of-Thumb:
Horsepower for driving a pump: For every 1 HP of drive, the equivalent of 1 GPM @ 1500 PSI can be produced.
Horsepower for idling a pump: To idle a pump when it is unloaded will require about 5% of its full rated horsepower

I have a list of parts started and the motors are not terrible, it’s the pnuematic chucks that attach to them that drives the cost up and of course the main pump itself. The bigger issue is I have some research in what valves and controls to use because hydraulics is not my background. The motors I need are around $400 each, chucks are $1500 each, pump, hosing, etc I expect around $6,000 in hydraulics total and I will still be integrating ac servos in the machine adding another $400 each. To be able to run dual spindles and have the kind of speed control, locking axis, etc.., the hydraulic pumps are a great way to approach it. 6000rpm capacity and can walk full torque at 1rpm if you need. I have most of the design worked out here but I need to farm out some work to a small casting company once I get the dimensional drawings for the motors I chose. That’s another aspect of this they really take a very small footprint for a ridiculously high amount of torque and fine degree of speed control. Budget is high where most would say buy a used machine and that itself defeats the purpose and need. Considering a new Tormach cost $28,000 with all the bells and whistles it shouldn’t be far off having a Swiss turn in the same ball park that can fit in a small shop or garage without taking away 300 sqft of floor space. Until I have it all resolved and the frame structure cast and ready I will refrain from making any final decisions and having a shelf full of parts.
 

Uguessedit

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I have a list of parts started and the motors are not terrible, it’s the pnuematic chucks that attach to them that drives the cost up and of course the main pump itself. Even knowing I am using automated chucks regardless servos cost that and then you need a spindle, bearings, housing to hold them and so on versus a dust/Swarf cover over the hydraulics. The bigger issue is I have some research in what valves and controls to use because hydraulics is not my background. How to plumb, what components, sourcing, etc.. The hydraulic motors I need are around $400 each, chucks are $1500 each, pump, hosing, etc I anticipate around $6,000 in hydraulics/pnuematica alone and I will still be integrating ac servos in the machine adding another $400 each. To be able to run dual spindles and have the kind of speed control, locking axis, etc.., the hydraulic pumps are a great way to approach it. 6000rpm capacity and can walk full torque at 1rpm if you need. I have most of the design worked out here but I need to farm out some work to a small casting company once I get the dimensional drawings for the motors I chose. That’s another aspect of this they really take a very small footprint for a ridiculously high amount of torque and fine degree of speed control. Budget is high where most would say buy a used machine and that itself defeats the purpose and need. Considering a new Tormach cost $28,000 with all the bells and whistles it shouldn’t be far off having a Swiss turn in the same ball park that can fit in a small shop or garage without taking away 300 sqft of floor space. Until I have it all resolved and the frame structure cast and ready I will refrain from making any final decisions and having a shelf full of parts.
 

JimDawson

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OK, your budget is realistic. Once you know the GPM and PSI of the spindles then you can spec the pump and servo valves. Rather than stringing hoses all over the place, a manifold block is a good place to start. You do all of your valving in that one block then just run steel lines or hoses as needed for the pressure, returns, and case drains. It's been about 30 years since I built a complex manifold, a 3D maze puzzle. :) You want to use steel lines where possible because hoses are a bit ''spongy'' and not the best for precise positioning.

Are the AC servos for running the axes?
 
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