[GreatNorthGnome]

I finished a conversion on my craftex B2227L lathe last week (woohoo, only took 2.5 years...) Anyway, I wanted to keep manual capabilities on this machine.
I just used the stock screws, mounted the z axis motor on a timing pulley to the lead screw on the tail stock end of the machine, then for the x I extended the lead screw out the back side of the cross slide and directly mounted the motor back there.
This lathe made that super easy since you can disconnect the lead screw from the head stock for cnc mode, then flip the lever back to manual driven lead screw.

My question is, now that everything is wired up, if I were to use the machine manually with the electronics powered off obviously. The lead screw will be spinning the z axis motor while the lathe is running, is there a possibility it could generate current and damage my drivers?
I have bullet connectors on the wire leads so I can just pop the cables off, but I was just curious what your guys thoughts were on that.

Thanks

[lcvette]

Not sure on the back end situation, may be wise to put a quick connect coupling so you can unplug the motors from the drives just to be safe.

Our of curiosity, I n ow ma Y people want to keep manual capability however that is completely possible to do with the keyboard using the jog functions which also gives you a DRO to use on the mach3 screen.

Now I'm not sure how accurate it will be with backlash from the stock screws, but I would recommend upgrading to some doublenut ballscrews and forget about the manual operation, it is a thing of the past once you start using cnc even for quick OD turning and facing ops you don't want to write a program for.

The only thing I could see what your doing being worth while is if you don't have a feedback on your spindle and need to do threading but then I would suggest getting that setup so you can do threading via cnc, alot faster once you get the hang of it.

With fusion360 being free for hobbyists and covering you cad and cam solutions there is not much reason to feel compelled to retain manual functionality. But if its a must for you, I would say be safe and disconnect the drive from the motor.

Chris

Sent from my XT1080 using Tapatalk

[GreatNorthGnome]

Thanks for the response. That's kind of what I am thinking about disconnecting them, just to be proactive in case it could cause harm.

I definitely don't disagree with you in terms of it being a cnc, I mean my mill is full on cnc mode with ball screws and I wouldn't change it since most of what I machine works best with that set up.
Don't get me wrong, the lathe will likely get ball screws one day once I get better with it just like the mill. But it's tough right now because manual lathes are my bread and butter, a lot of small one off parts I need to make I can do faster manually than I can program/draw and machine. This simple conversion gets me my rads and tapers I couldn't do easily before, and while z has a horrendous amount of backlash, (x is manageable though) the parts I do aren't really affected by it since its all Z- feeds as long as I remove the backlash before a movement. Plus appearance is more important vs accuracy.
So that's kind of why I'm adamant about keeping it a hybrid for now. I have so many years on these machines that I know I can transfer over, eventually

An encoder on the spindle so I can set up threading will be a very useful feature that I am looking into however! Changing gears on these machines drives me nuts...

[lcvette]

Have you looked at the machine Lathe plugin for quick turn features? It is pretty close to conversational programming where you can string several operations together based on your part dimensions without leaving the control panel.. I use it all the time.

If you have all your tools setup on a quick change tool post and your home switches installed with the tools set to the spindle axis. You can make a program in about 1 minute depending on the complexity of it. The plugin has pretty much all of the operations you could hope to need to turn.

But again the caveat is having repeatable movement and tolerances with the machine axis. Once that is done though there is no way manually doing it would be faster when you consider all of the size checking you have to do while sneaking up on sizes. It will require a little learning curve to become comfortable with the plugin interface and getting a handle on the dimension entries and what they mean but that will take about a day or so of using it, after that... It's fast as lightening.. And you can save your code so if you ever need another one its already done just chuck up part, ipen that file and hit the boogie button!

Sent from my XT1080 using Tapatalk

[GreatNorthGnome]

You're doing a good job of convincing me haha like I said, it will probably happen. I have a length of 1605 ball screw material behind my desk at work that will probably get both axis out of the way. Just need a couple nuts.

[lcvette]

If you Know the pitch you can order the nuts, I get them direct from China, they are very inexpensive.. Just make sure the 1605 will fit the X slide, my guess is it won't from the looks of the machine.

But most of the suppliers I've spoken with offer a variety of sizes and Precision classes.

Double nuts are a MUST in my opinion for getting backlash down. I Know for my mini Lathe build I used a 8mm ballscrew.. And it was only available in a higher class which was fine for me the cost was only marginally higher given the short length that was needed.

Besides, for holding diameter tolerance you want the accuracy on X to be pretty damn good!!

You will be amazed how awesome the machine is after you convert to ballscrews and get your backlash down really low (I wasn't able to see any backlash on the 10mm double nut ground ballscrew for X on my .0005" starter indicator) and Z I was able to get the 1605 double nut down to probably what looked like .0001" (indicator was still on the line just not perfectly centered over it, damn close enough though) with some custom shimming without any binding.

After that and getting the motors tuned to the correct steps per inch you basically have a full DRO in mach3 which is fabulous.

I use machstdmill and mach3, and it uses a master tool to set tool length offsets, so all of your tools can be setup and all you have to do is touch of X and Z with the master tool to the stock and you are ready to run.

Not sure what software you use for cad/cam, but for mine I know once everything was setup, even basic turning operations we faster with cam software. I just modeled out the part really quick, then set the stock size parameters and my cam basically does the rest based on my tool list entered in. Then hit post process and load the program in mach 3 and away it goes, just have to change tools when needed.

So much better with full backlash free cnc. The finishes are superior to manual and take much less time to accomplish in my experience!!

I sold the small cnc mini lather shortly after converting it and bought a much larger Lathe to convert which I will start after my mill project is back up and running.. Can't wait.. I miss cnc on the Lathe like no bodies business.. Going back to manual is painful and after you get spoiled.. Lol

Good luck!

Sent from my XT1080 using Tapatalk

[GreatNorthGnome]

Oops, thought I replied days ago..

Nah 1605 wouldn't fit in the stock location now that i checked. Might have to look into some smaller alternatives. Oh I know man, my mill needs double nuts or over sized balls since the 1605 ball screws and nuts I got for it have a fare bit of play. I mean its good enough for most of the work I do on it, I'm not machining bearing blocks or anything, being "pretty" and "cool" is more important haha... but when I first built my cnc mill I machined custom acme lead screws with nylatron nuts. Rapids were only 40ipm at best, but it had zero! back lash and cut the most beautiful holes lol So combining the speed of ball screws with zero backlash, would be pretty awesome.

Software I haven't committed to anything yet, anything "crazy" that I can't program by hand I just do at work with our software and then take a flash drive home. I've only really given Cambam a good honest shot and actually really like it, i mean its no mastercam but it does the job. After you mentioned fusion 360 I tried it out but man is it a heavy program, bogs my old computer down pretty good. But that only lasted a couple hours before it prompted me to update my graphics driver, now I can't use it anymore, screen is grey and I cant see anything. Tried switching a few things using their FAQ and no bueno... so that was short lived. Still searching off and on for cam software.

I bet! I'm sure once I get the full cnc lathe experience I'll be a little more open to it. Thanks man.

[lcvette]

I think what you will find is all vad cam software worth anything is going to require a decent computer system to run effectively. I ran solidworks on a laptop for a while and struggled with it being really slow once I started adding components into an assembly. Eventually I bit the bullet and bought a $600 lenovo entry level cad workstation, it came with the entry level nvidia quadro graphics card, 8mb of ram, solid state hard drive and Intel core i7 4770 (if memory serves).

WOW what a difference the right machine makes.. That was by far one of the single best investments I could have made. For CNC and designing parts especially for conversions it is far simpler to design the machine into a solid model and design all the components for it by actually building it in the modeling software. This ensure fitment of everything and when you are done you simply flip to the cam tab and get your machining strategy built. This allows for a wealth of design freedom to try different ideas and get the best and simplest design to work.

Once you have a machine that can handle the software and a solid understanding of how to use it (now days it has become pretty darn simple) you will be amazed at what you can design and build.

So I would suggest looking into a system that will allow you the freedom to design, it will have a tremendous impact on how much you enjoy the experience and really help to expand your capabilities.

For me, I spent a weekend setting up my cam software with all my tooling, defining my machine parameters, putting my machine model into the simulator and defining machining strategies to use with the auto feature recognition function. so it is now to the point where once I have a solid modeled part completed it is seldom more then 4-5 mouse clicks to complete the cam programming and have Gcode ready to run on my machine with my available tooling and all feeds and speeds set automatically. Before that it was cumbersome and took a while going through each and every detail of each operation.





Sent from my XT1080 using Tapatalk