# Considering Un-cnc Ing



## Transformer (Dec 9, 2015)

About a year ago I CNC's my Grizzly lathe, a G0602.  This after only about 6 months using it as a manual lathe and no prior experience.  It was an interesting exasperating experience, but now it is all functional.  I can do basic G code programming and am building up a set of programs I can easily modify and use.  The problem is with the simple one off stuff I do it is just so slow to write a program, make sure it will not crash my machine, and frequently have to repeat this process it seems it would be faster to convert the lathe back to manual operation and just dive into things without all the before turning the machine on steps.  Has anyone gone through this and then taken the step "backwards" or considered it and are glad they did not do it.  All comments appreciated.


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## chevydyl (Dec 9, 2015)

Uh why don't you just add manual crank handles to the screws, then have a switch to disable the drives if needed, my mill has a switch to enable and disable the drives. Depending on what motors you have you may have to deal with back voltage, brushed DC motors will create Voltage when rotated when off, that Voltage can be enough to fry your drives, my ac servos, brushless, don't cause a problem.

I just did a job that was better suited to manual machining, I just used the cnc part to feed from x0 to x16 to x0 over and over and over and over...... while it was feeding 16 inches at 4ipm I went and did something else, can't do any multitasking while hunched over a lathe cranking a handle slowly for hours


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## wrat (Dec 9, 2015)

Transformer said:


> Has anyone gone through this and then taken the step "backwards" or considered it and are glad they did not do it.  All comments appreciated.


It seems that few shops have no conventional lathes.  Even a modern, fully automated shop will have a manual machine tucked back in the corner somewhere until such time they have so stinkin' much work they just can't sacrifice the floor space any longer.

As everyone that gets into this realizes, it's not just the machine, it's all the support, be it tooling, talent, or time.  Naturally, if you were a thriving business, the answer would be to just go buy another machine.  Wouldn't that be nice, eh?

Still, considering the de-automating of a machine, to me, is kinda like saying "these new pipes make clunky noises and i think that one is starting to sweat; and that flush toilet is almost scary. We need to get rid of all this indoor plumbing."  At least that's how it hits me.

When i read your post, what strikes me is total noob, then 6 months of cranks, and then a *whole year* of NC.  Give it some time.  You're barely into getting any real programming chops (IMO).  If you had been under the tutelage of a Master this whole time, in another 6 months I'd consider you adequately trained.  But i'm kinda Old School, that way, sorry.  If you were in a solid production shop - where someone else built your tooling; ground your tools; and wrote your programs - you'd be Capable as of now. 

So, IMO, the LAST thing you wanna do is dive into changing your machine.  Just put in your "chip time".  Continue on your course.  Problem solving and making workarounds is, to many of us, what makes this so interesting.  Slogging through the drudgery is what makes the cool jobs all the more sweeter.

Sure, the one-on-one feel of cranking a lathe is hard to beat and, like you said, a one-off operation might be better served with a conventional lathe, you're probably right.  So do a trade study.  Make a record.  When something undeniably fits better on a conventional, write it all down and estimate that hours and $$ saved had you had a conventional sitting there.  After you've accumulated some of these entries, compare it to your overall workload and see what the proportion is.  If it's truly a problem that requires a solution, I still keep coming back to buying another [lathe]; even an Atlas or similar machine might suffice if you have the floor space.

Wrat


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## JimDawson (Dec 9, 2015)

I am a real fan of convertible machines for home shop and prototyping work.  I would take a hard look at making your lathe quickly convertible.  It will be an interesting engineering excersize and useful in the end.  Some day I will be CNCing my lathe and it will be designed to retain full manual operation with a change over able to be accomplished in seconds.


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## coolidge (Dec 9, 2015)

wrat said:


> Even a modern, fully automated shop will have a manual machine tucked back in the corner somewhere until such time they have so stinkin' much work they just can't sacrifice the floor space any longer.
> 
> Wrat



Wrat nailed it! ^^^


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## sbx (Dec 9, 2015)

What about a pendant, or other control capabilities. Or, if that's not working for you, why?

I ask also for personal reasons, as I'm thinking that with a game pad style pendant, you could do most any manual operation without programming through jog commands. This would be for a mill for me. But same concept should apply to a lathe I'd think.


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## wrat (Dec 9, 2015)

JimDawson said:


> I am a real fan of convertible machines for home shop and prototyping work.  I would take a hard look at making your lathe quickly convertible.  It will be an interesting engineering excersize and useful in the end.  Some day I will be CNCing my lathe and it will be designed to retain full manual operation with a change over able to be accomplished in seconds.



In spite of my initial verbose response, i agree in principle, with what you're saying.  In a home or proto environment, yes, good idea.  Very cool.  I'm just not aware of any such models.

But like dual-purpose cars or bikes or whatever, at first blush it seems that such a lathe would have to be purpose-built and designed from the ground-up to be effectively and usefully convertible.  Surely there's more to it than detachable cranks.

For instance, is there a small NC lathe with a compound?  I don't know of any.  If a guy started with a conventional and converted that one, he'd have a compound, i guess.  And you'd surely want compound functions in conventional mode.  So would that have to come on and off quickly and precisely?  I don't know.

And what about feeds and/or threading?  Initially, it'd make sense to just keep the steppers in place for spindle speed and screw. No need returning to a gear cluster, I wouldn't think.  But then, if a guy does that much, then why depend on a hand crank at all, when the stepper could engage, disengage, and repeat much cleaner and closer?

Guess that could be solved by carrying a full transmission and spindle gearing and just run things in neutral for NC mode.  Then, i guess, have a disconnect for all the motors in conventional mode.  Just thinking out loud, here.

So it sounds like a very interesting idea and project to get into.  Might be very cool.  I'll be looking forward to seeing how you approach it.

Wrat


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## T Bredehoft (Dec 9, 2015)

I put a (non-CNC) power feed on my PM25 (yes, I know, it's a mill) and almost lost hand cranking ability. I had put a belt tensioner in the drive, relaxed it and found I could crank the table just like always. If your drives involve toothed belts, perhaps obtaining longer belts and putting tensioners in them could be your answer, Loosen them and have a hand mill, tighten them and run CNC.


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## bpratl (Dec 9, 2015)

About a year ago I also converted my 602 to full CNC and I find that it is no problem in using Mach3 turn wizards and or the MDI command window in doing one shot turning, boring or simple repairs.
I also use a wireless MPG for  setting up the lathe and I am presently looking into using two MPG's , one for X and one for Z,  as I dislike switching the pendant between the two when I am in the manual mode.
I am very pleased with this setup and I would not consider uninstalling the CNC setup.


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## Bill C. (Dec 9, 2015)

In my experience in the trade I used conventional machines, I was lucky if they had DROs.  I grew up being able to feel the tooling resisting the machining. I was thinking about the discussion about spot drills the other night. I grew up with center drills but I bet i used the spot drills as counter-sinks sometimes. 

I have loaded, unloaded and oversaw a CNC workcenter in one shop. I can understand a home shop having one if they were selling replacement parts due to their ability to change programs and fixtures in a short setup time.


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## T Bredehoft (Dec 9, 2015)

When I got back into machining, after a 15 year retirement, it was with the hope that I could machine a plotted curve. (the curve I wanted to machine is/was long S shaped.)  I soon realized that my old system of bandsaw/file was going to have to do because the cost of the CNC equipment far exceeded the realized benefits of the machine.  Yes, I now have a lathe and a mill, and yes, I still bandsaw/file the curves I need, up to 17" long. I can program my computer to draw the curve, and I can cut it out and trace it on aluminum, but I find I have to tweak it after it's cut.


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## compsurge (Dec 11, 2015)

How are you doing the coding now? Are you using any of the conversational programming wizards available in Mach or LinuxCNC? I don't see how manual over these wizards and CNC motion will save a tremendous amount of time based on how quickly you can turn with CNC versus manual movements. What tools do you primarily use?


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## Transformer (Dec 15, 2015)

Thanks for the responses. 

Wrat:  I hear you.  I will move slowly, if at all.

Jim Dawson: A convertible machine would be great but I would not know where to start.

bpratl: So I think the MDI lets you input one line of code at a time and immediately run it.  I have never used this approach but for boring involving multiple passes wouldn't you need 4 lines of code -advance tool-cut-retract tool-return to start, repeat, repeat, repeat.  I hope I am missing something here.
Also I think an MPG unit only allows you to position the tool and not control it during cuts, or can you use it for more than a replacement for keyboard controlled movement?  In general your response gives me hope - sorry for my lack of understanding.\

compsurge:  I manually code.  I do not use the Wizards although I have used them to help me learn how to code.  I do not use any special tools. 

A recent job.  I had to bore out a piece to take a toonie (Cdn $2 coin), about 1.13".  I step drilled a hole to .75" then used a boring bar to widen the hole to full size. I moved the boring bar by turning the stepper motors by hand - they have a small wheel on the projecting unused shaft. It was all done very quickly and I did not need to program or work out in great detail where to start and how many cuts to make.  I just did it on the fly, cut is too big, back off and so on.  Of course the fact that great precision was not needed made it easier.  As a one off job, given my novice programming and nervousness over crashes this was certainly the easiest approach and one which I think even increased experience and confidence would be hard to match.


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## JimDawson (Dec 15, 2015)

Transformer said:


> Also I think an MPG unit only allows you to position the tool and not control it during cuts, or can you use it for more than a replacement for keyboard controlled movement? In general your response gives me hope - sorry for my lack of understanding.\



The MPG can be used to control the lathe somewhat like using the hand wheels.  The down side is that you can only control one axis at a time so it is a bit slower to use than the hand wheels.



Transformer said:


> Jim Dawson: A convertible machine would be great but I would not know where to start.



Like any engineering project you start by actually defining the need and the goal, then step by step solve each small problem as they come up.  In this case it's how do you design a mechanism that will quickly disconnect the lead screw and allow operation with the hand wheel.  I don't see a problem with leaving the cross slide connected to the stepper.  I would think that you would need some kind of a DRO for manual operation.


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## bpratl (Dec 15, 2015)

Transformer, give the wizards a try, I used the boring wizard to enlarge the ID on 12 bronze bushing and it worked out great. It did it in 4 passes, with automatic retraction and a final skim cut.
It's plug and play and you can save the g code.  I am presently in the process of wiring in two MPG's for X and Z which should be done by XMAS I hope. I will report back when working. Bob


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## maker of things (Dec 15, 2015)

I run many programs line at a time with MDI (assuming mach3/4).  Up arrow shows you the recent lines you have entered which you can then arrow over and edit.  I frequently use this approach when running simple passes.   Do you have another way to measure movement without the motors driving the move?  i.e DRO or verniers.


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