Servo Drive For a lathe Compound

These ideas are pretty darn good but the idea has distracted me from the couple of projects that I'm working on. There have been plenty of times that I have had to suspend a project to make a tool so that I could continue the project. (I have even had to make a tool, to make a tool, to make a tool, to make my project - no kidding!) This time I backed off a notch and borrowed a higher quality cordless drill than the one I was using and by using my attachment gizmo I'm able to get an acceptable finish on the flywheels that I started out to make in the first place. Sometimes Milwaukee does make better tools than Harbor Freight.

The idea of the double ended shaft on a stepper motor may be the way to go. I have to look up dimensions and see if it would fit in the allotted space. It needs to be simple to use either the power feed or manually operate it for using the settings on the standard dial without major disassembly and installations each time.

I have been looking, and trying to study, the interesting makeup of stepper motor circuits but I realize I have a lot to learn before I can proceed in that direction. I even, almost, broke down and bought a cheapie x-axis mill drive off of Ebay. After experimenting with a "good" drill I think that staying with that will be the most worthwhile thing to do for now. That doesn't mean I'm throwing in the towel. It means that I'll be doing some more reading and searching and slot it in as a project to do between other projects. I've tried to convince my wife that I can't die until I have all my projects done. Right now I'm going to have to live to about the age of 562 years.

One of the fun aspects of this hobby is that every time you get involved in making any kind of a neat gizmo it opens up avenues to making other neat gizmos. In this case it has opened up an area of learning that I had never looked at before.

Right now I'm working on that "Crazy Joint" that Brian Rupnow came up with - because it looks really neat. And I'm restoring a 1929 John Deere 1-1/2 hp. engine - because it will look nice sitting with my John Deere tractor at shows next summer. My approach to both of them seems to contribute to the growing pile of chips in my shop.

I will continue - no matter how big of a mess it makes.

lkrestorer said:

The idea of the double ended shaft on a stepper motor may be the way to go.

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That's why I'm looking for a hollow shaft, the idea, extend the existing shaft through this hollow shaft, then figure out a clutch to engage it to the motor shaft. When not engaged, the extended shaft along with the original scale and hand crank are used to manually operate the compound slide.

lkrestorer said:

my John Deere tractor

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I assume this is an antique 2 cylinder model. I used to own a Series 60. I've been to a few of the 2 cylinder conventions here in Iowa.

Go to this site & search for DC motor controller https://www.mpja.com/ & just DC motor & scroll up & down . yer bound to find most of what yer lookin for & for a pretty good price
animal

RonGinger , did you take any pic's or documentation during construction of yer project ?
tks
animal

ignator said:

I assume this is an antique 2 cylinder model. I used to own a Series 60. I've been to a few of the 2 cylinder conventions here in Iowa.

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Yes, it's a 1939 "B" row crop. The 393'rd "Styled" Model B that was built. Restoring this old stuff is what got me started in hobby machining. Many of the worn out parts can be recreated easier than finding good usable replacements.

animal12 said:

Go to this site & search for DC motor controller https://www.mpja.com/ & just DC motor & scroll up & down . yer bound to find most of what yer lookin for & for a pretty good price
animal

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Oooh! Another new place to browse through. It looks like they might have some interesting stuff.

A lot of the DC motors that would maybe work for this have a built in gear train. I think this would be a problem because they would need a clutch of some sort and that means more parts and would be more complex. A double shaft stepper would be free wheeling with the power off and would revert to the handwheel when not being used without needing a clutch.

lkrestorer said:

A double shaft stepper would be free wheeling with the power off and would revert to the handwheel when not being used without needing a clutch.

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Ones with enough torque would be large. Agree that adding a clutch mechanism complicates this.
I see the milling machine power feeds have some competition on eBay selling for ~$125USD (half of what they had been). Complaints are the keyway is metric, and does not come with the extension shaft to attach the original crank (for Bridgeport install). This would work on my big lathe, but would be in the way.

Actually steppers May suffer from cogging and may not feel Smith when turned. Even worse the drive may short the windings effectively locking the shaft. Depending upon the feel you want to achieve yo may need to disconnect the stepper from the drive. There are a number of factors here but you might not get the silky smooth feel of a plain mechanical leadscrew.

lkrestorer said:

A lot of the DC motors that would maybe work for this have a built in gear train. I think this would be a problem because they would need a clutch of some sort and that means more parts and would be more complex. A double shaft stepper would be free wheeling with the power off and would revert to the handwheel when not being used without needing a clutch.

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ignator said:

Ones with enough torque would be large. Agree that adding a clutch mechanism complicates this.
I see the milling machine power feeds have some competition on eBay selling for ~$125USD (half of what they had been). Complaints are the keyway is metric, and does not come with the extension shaft to attach the original crank (for Bridgeport install). This would work on my big lathe, but would be in the way.

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Those “Servo ” type drives that are used on a Bridgeport mill are way to big for most lathe compounds. Even some of the pictures posted earlier had me shaking my head.

Given that the only way I see to do this up right is to design your own clutch mechanism. Then use a compact motor to drive the compound when needed.

Wizard69 said:

Those “Servo ” type drives that are used on a Bridgeport mill are way to big for most lathe compounds.

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Ikrestorer posted a photo he found of it being mounted on the compound. My reply was I believed it to be too big of a power feed in that location.
I copied that link here;

ignator said:

Ikrestorer posted a photo he found of it being mounted on the compound. My reply was I believed it to be too big of a power feed in that location.
I copied that link here;

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Yep that is the one. Probably OK for a special purpose late but for a genral purpose tool room lathe it would seemingly be in the way more than actually being useful. This is the type of solution where you buy a second compound and swap compounds when you really need controlled feed.

err! Auto correct madness, that Smith is suppose to be "SMOOTH". This is why I mentioned using a mechanical clutch someplace in the past in this thread, if you want manual use and the smoothness of a mechanical only system you need to disconnect the stepper. Of course with a simple belt drive you can just remove the belt.

Wizard69 said:

Actually steppers May suffer from cogging and may not feel Smith when turned. Even worse the drive may short the windings effectively locking the shaft. Depending upon the feel you want to achieve yo may need to disconnect the stepper from the drive. There are a number of factors here but you might not get the silky smooth feel of a plain mechanical leadscrew.

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In my forum browsing I ran across this thread: https://www.homemodelenginemachinist.com/threads/arduino-rotary-table-for-dummies.26744/

This is about controlling a rotary table but there isn't really much difference with what I'm looking to do. It goes into the electronics in great depth for someone who hasn't played with this particular stuff much. I got a kick out of the fact that he asked his wife (with no previous experience) to put it together and she did it just fine. I am no stranger to electrical stuff, just to this type of equipment so my fascination level has taken a jump. bmac2 has gone into great detail suggesting components and that is really what I need.

His project is about exact positioning and the only exact positioning I would see a use for would be to establish travel limits. This could include adjustable limits to eliminate crashing the whole mess into a part being machined. With the different sizes of motors available I will try to find something that will work.

And that brings to mind another idea. I have seen the standalone rotary tables like this setup and thought that could be a fun accessory to have. I have an 8" Phase II table and wouldn't that be an interesting variation? The articles I've seen have been about the little tables but wouldn't an 8" work the same with just a more powerful motor?

Do you see where this is going? More projects! Bye, I'm heading for the shop.

Take a look at:

Thread
Arduino Rotary Table for Dummies

It shows stepper motor contols for a similar application but on a rotating table. You likely could adapt this method to your compound.

SailplaneDriver said:

Take a look at:

Thread
Arduino Rotary Table for Dummies

It shows stepper motor contols for a similar application but on a rotating table. You likely could adapt this method to your compound.

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Yes, that was what I was referring to in my last post. I'm going to do some digging and see where it takes me. I needed some specific direction because this Arduino thing is very new to me.

lkrestorer said:

Yes, that was what I was referring to in my last post. I'm going to do some digging and see where it takes me. I needed some specific direction because this Arduino thing is very new to me.

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The hardware in bmac2's project is solid and will work, but you will need to modify the program code for the Arduino. Specifically, his program takes input from the user and then translates that into the number and direction of steps necessary to rotate the table to perform the desired action. Instead of steps per degree of rotation, you would need to modify the code to use steps per amount of travel. Additionally, his program uses a single constant step rate - to vary the feed rate you would need to add the necessary code to vary the step rate accordingly.

The Arduino uses a programming language that is structured very much like C++ and the programs are called sketches - you'll need to go to the Arduino website and download the development software (it's open source & free). If you are not familiar with the Adrduino environment, this might be a bit much to take on for a first project. There are lots of online tutorials, and "Arduino for Dummies" book is a good starting place. On the plus side, you can start with bmac2's sketch and modify it as needed for your application. If you do that, I'd strongly suggest making small changes, one at a time, and verifying each before going on........

To test your changes you will need a hardware setup the same as what bmac2 used: arduino board, display, keypad, plus a power supply, stepper driver and motor. Note that what can appear to be identical devices, such as the display, may have some differences when it comes to programming - read bmac2's entire thread and you will see what I mean. You can do the whole thing for well under $40.00 if you start with a small stepper for testing purposes. Then when you have everything working move up to the actual stepper you will use.

The programmed Arduino controller outputs step and direction, which are used by the stepper motor driver to control the stepper motor. This means you can choose any stepper motor with enough torque for your application and a driver and power supply rated with enough current for the motor.

While you can program the amount of travel, I would still advise using some type of limit switch arrangement to limit over-travel. You don't even have to include them in the Arduino program - just series them with the enable input to the stepper driver. Same for an E-stop button.....

Hope this helps!

Tim

Chuck Fellow did a stepper RT design:

https://www.homemodelenginemachinist.com/threads/electronic-dividing-head-using-the-arduino.17896/

My recollection is that his sketch included a constant rotation mode. If all you want is variable speed rotation, you should be able to do so with an oscillator input into the stepper controller.

TimTaylor said:

Hope this helps!

Tim

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Thank you Tim. I'm beginning to see the start of a new branch in my hobby world. I thought that I was out of the studying world and just working on refining my techniques but it looks like this is just the beginning. The intriguing thing about this is that it requires an understanding and application of the electrical equipment along with the mechanical modifications to whatever you are trying to control. Right now I'm happy I didn't jump the gun and buy a Chinese mill axis drive and modify it to fit my compound. Actually, I'm wondering if trying to upfit my 8" rotary table would be a better place to start and leave the compound feed for another time.

I understand your point about making only one change at a time. That is an old troubleshooting and repair technique. Never throw too many new variables into the mix and expect to understand what happened. You may get your intended result but you won't know what did it.