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  1. #1

    Join Date
    Jul 2020

    Flashcut 3 setup for Sherline lathe

    Some folks here were kind enough to get me over one major hurdle setting up my old, but new to me, Sherline lathe with a Flashcut 401A. Thanks datac and machinehop5!

    Now I am at the next phase of setting this machine up. I am running Flashcut 3. I tried v4, but it required an upgrade. So it's v3 for now. My lathe has 4 of these steppers (https://www.flashcutcnc.com/product/...stepper-motor/). I have noticed that when I try to set up the configuration, I am only able to use two axes when I set it up as a lathe, but all 4 become available when configured as a mill. Is that a typical setup on a lathe, to run it as a mill for a workaround? That seems counterintuitive and complicated. Or am I just setting it up incorrectly?

    Also, I have learned that I do not have a spindle encoder, so my spindle is just set up as another axis. I assume that means I will not be able to do any threading, which is a problem I will have to solve. Can anyone make any recommendations on an encoder I can add to my system? I can call Flashcut tomorrow to see if any new equipment will be compatible, but I don't want them to be my only option if there is something better.

    I would greatly appreciate any recommendation or advice. It's a big learning curve!

  2. #2

    Join Date
    Jul 2020

    Re: Flashcut 3 setup for Sherline lathe

    I wanted to add a photo of the lathe. It has some gearing on 2 axes, one of them being the spindle. The 4th axis is on the tailstock, which I guess would be for live tooling. Though I'm not entirely sure why anyone would want live tooling on the tailstock since the part should already be spinning in the spindle. It came with a custom made delrin toolpost with a carbide cutter in it. The original toolpost came in a box and looks like it was never even used once. It was clearly used for a very specific operation. I'm not sure what they were doing with it. I just need to figure out how to make it work for standard lathe operations. Figured a photo would help.

  3. #3
    Join Date
    Mar 2004

    Re: Flashcut 3 setup for Sherline lathe

    Quote Originally Posted by tinkerdad View Post
    You definitely have a sherline lathe turned into a speciality machine. The Stepper on the spindle is far from typical for a conventional lathe setup and will sure limit you on rpm. For a special use machine, its fantastic.... for general turning, not so much. With the 4 stepper driven axis, it sure can do some interesting things, including threading without an encoder by coordinating motion necessary to create a thread. Somehow I'm not sure your quite up to the task based on your comment about learning g-code, but certainly, dont be afraid of figuring it out. I'd put a lathe like that to use doing something.....

    Your Flashcut control can be configured to do what ever you want regards how many axis it controls, but you will need to decide exactly what your going to do with that lathe. If you want something traditional to a lathe, you will need to replace, restore, or one off a new spindle drive system using a regular motor of sorts like the original does. There are many, many options for this fix, from plain old AC motors with step pulleys for speed control, 3 Phase spindle motor powered with a small VFD for variable speed capability, a 90v motor and drive (typical to many small machines like this), or even a Servo Motor of adequate size, being driven by a Servo Driver via Flashcut itself.

    Frankly, you almost need a gear-head neighbor or friend to help you get under way if this is all new to you.

    The live spindle I would keep intact... That appears to be just a second sherline spindle mounted just like the other side. That can come in handy down the road.. But, given your new to all of this, i'd focus on getting a real motor on your spindle first, spend your time learning to create basix X-Z code typical to that machine and then get deeper in down the road.

    If your going to do threading, you will need to add a simple encoder, but also, your FC signal generator has to have an add-on board to process the information from it. Now if you want to be even more confused, some fellows would opt to find a way to run a regular motor on your spindle as a traditional lathe, but engage the current stepper motor for jobs that could use the specific positioning of that axis under FC control. Note however that you would never run the regular motor AND the stepper together at the same time on the spindle because you will turn the stepper into a generator that would probably over backfeed your motor drivers and blow them up.

    Don't get dismayed with what you have there... could be fun. You could even entertain selling the second sherline spindle to help pay for a new spindle drive motor setup. Sherline does sell that separately....
    Chris L

  4. #4

    Join Date
    Jul 2020

    Re: Flashcut 3 setup for Sherline lathe

    I am admittedly an amateur with G-code, but not with basic machining, mechanics or technology. I have been in the manufacturing business for 16 years. I have other specialty machines that run programs, they even have optical encoders too, they just don't run g-code. I can build a PC, hack it to run MacOS and fix most things on any of my vehicles. I also happen to be an industrial mechanic. So I am that gear-head you speak of, just new to this specific equipment. I would never claim to be an expert in machining, though. I fit the old saying that I know just enough to get me into trouble. But I also know enough to use a lathe and mill to financially save my butt enough times a year that it makes it worthwhile to learn something new, like g-code. I have owned a lathe before and also own a much bigger mill. It's just the CNC and g-code that is brand new to me. I'm looking to use this lathe in my shop to support my work in industrial mechanical repair, to make or repair small parts when it's faster or cheaper than ordering a part. So I am looking to use it for my business, and will pay my dues to learn g-code. I'm not trying to toot my horn, I just wanted to make it clear that I am not TRYING to make this lathe work for me, I MUST make it work for my business.

    The problem I have now is that I bought old, unsupported equipment. I knew that when I bought it. I won't need help with basic machining or designing parts in CAD, I do that for a living already. But I acknowledge that I will need to do a lot of learning with the programming and basics of CNC machining. I do understand that going from manual machining to CNC machining is going to be like opening Pandora's box, but I need to learn sooner or later, and I'm not getting any younger. The solution is that I could simply pay to replace it with more modern, better supported equipment, and get help from Flashcut or wherever the retrofit kit comes from. But for my intended use, as a machine to make a quick part in house every now and then when I need it, this setup should be more than I need for the time being.

    What I need is a nudge in the proper direction. You say this lathe could perform threading without an encoder? I have ran threads on a fully mechanical lathe, I understand how it works, mechanically, using gears and a lead screw. Adding the stepper motors and a PC is where I am in new territory. Are you really sure that I could potentially make a program to run threading on this lathe as it is set up right now? What I mean is that I could do precision work like threading without switching to a more traditional motor on the headstock? It doesn't confuse me to think about having two motors on the spindle and being able to switch between them. What does confuse me is simply what the g-code would look like if I were using the stepper to run the spindle. Can you share a little more about how I could program g-code to run threading with this stepper without an encoder?

    As for using it as a traditional lathe, I would be open to modifying it to also run a more traditional motor. However, if I can program it to run this stepper and get done what I need to be done, that would be amazing.

    While I am not rolling in dough, I could certainly afford to keep the second headstock and still buy the necessary parts to equip the lathe with what I need. If it can run at high enough RPM, I could also delegate the extra stepper motor to run the spindle on the mill. Although, my lack of experience with Flashcut and g-code leads to the fact that I don't understand if Flashcut could drive a stepper and servos at the same time if I were to buy the servo driver. Frankly speaking, I barely understand the difference between a servo and a stepper. But like I said before, I'm more than willing to learn.

    Let me know what you think about the possibility to use the existing stepper as the spindle motor. I'm really curious how that could work. If it's possible, I would entertain the idea of doing whatever I have to do, or learning whatever I have to learn to do it.

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