New Electronic Leadscrew Project

[Paul Alciatore]

Back in the 1960s I studied some control systems that used analog computers. Precision pots that were a foot in diameter, 1% and better components and they still had to be tweaked to get three place accuracy, etc.

There is a reason why digital computing has taken over in almost all applications. Analog computers do work, but it is hard and expensive to get the accuracy that a digital machine will come by naturally.

Today a $25 digital device can compute with more accuracy than a $100,000 device of that era. Or of the present era, for that matter.

It was "which" Emco they copied. It would have been a different world with they had copied the V10.


For those that don't want to deal with the "cnc" aspect, what we need a small continuously variable transmission (couple of of cones?) instead of a quick change gearbox driving the lead screw. They you could cut anything within a range at the turn of a knob

[ulav8r]

A simple ELS would be great for my approximately 100 year old pattern makers lathe that has a power feed but does not do threading. It is slightly heavier than an Atlas 6x18 so would be fine for projects such as making 5/8 x 30 threaded dies for Lyman 310 tools.

[skunkworks]

I don't understand... 3hp wasn't enough to thread? You can make a potato thread.. here is a 500w emco with it's crap steppers threading aluminum....

Problem is the majority that do "just CNC it" never get to the point of threading,or if they do,they find out their hardware is adequate for everything,except CNC threading.
The latter happened to a friend of mine about three years ago.He converted a Grizzly 13x40 to CNC,then found out the 3hp motor and VFD he bought were not up to the task,so upped the anty to 5hp and a vector drive($850)then found out that closed loop stepper or full on servo motors it must be(+$1800) That and a full year of his spare time and about a month of my spare time to get all the hardware sorted out.

It works fine now,but only after a lot of childbirth.He was partially fooled into thinking it would be easy,by having converted a mill previously(cake walk by comparison) and by all the youtube videos of "CNC threading linux..blah,blah,blah" where the video shows a piece of Aluminum,plastic,or shudder even wax being threaded,just long enough for a nut to thread on.

[J Tiers]

Problem is the majority that do "just CNC it" never get to the point of threading,or if they do,they find out their hardware is adequate for everything,except CNC threading.
The latter happened to a friend of mine about three years ago.He converted a Grizzly 13x40 to CNC,then found out the 3hp motor and VFD he bought were not up to the task,so upped the anty to 5hp and a vector drive($850)then found out that closed loop stepper or full on servo motors it must be(+$1800) That and a full year of his spare time and about a month of my spare time to get all the hardware sorted out.

.......

Makes no sense..... I can thread just fine with a motor 10x smaller than that. The problem may be elsewhere.... having 5 HP is not a basic requirement for threading. It sounds more like the CAM program was at fault, as if it was trying to do full depth one pass threading.

There are dozens of videos of CNC conversions threading, NOT by any means threading wax.... Most that I have seen are taking a number of passes, not any of which would take 5 HP.

That whole concept seems just way off the wall to me.

If there was a complaint about the feed motors, I might be less inclined to question the matter, since in most they are required to hold the crossfeed and drive the threading feed. But even there, the cut is adjusted to bring it within the capability of the machine.

There just has to be something wrong with the CAM program, or inputs to it. If I can thread by hand on a 1/3 HP 10" machine, there is no possible way that it needs 5 HP to do it on a machine only slightly larger.

[RB211]

Why is it the naysayers to home shop CNC most likely are using professional grade industrial machines at work?

[skunkworks]

BTW - that video I posted was using the printer port.. (with a 100 line encoder + index)

sam

[Dan Dubeau]

Why is it the naysayers to home shop CNC most likely are using professional grade industrial machines at work?

Would you want to fly airliners for a hobby? Or would you or most professional pilots gravitate more towards an ultralight or home built where everything is pilot controlled?

As someone who fits that description I think it just comes down to personal preference and they type of work you do. The things I make at home are different than at work. I don't have a need for a CNC lathe, nor would I want one. For a lot of stuff, programming a part just isn't faster than cranking the handles. Unless there is a lot of material to come off, or i'm making multiples. I just simply prefer to turn manually. IMPO it's just faster. Even at work there are lots of times I'll just run a few parts off on the hardinge, instead of firing up the Nakamura. If the QTY is under 5, and it doesn't involved threading, tapers, or curves, I'm usually faster with a manual lathe. I've been bit a couple times though when I've made 2 or 3 of something, and the customer has come back and ordered 100. That really sucks.

On the other hand give me a CNC for millwork over a manual all the time. Unless I'm drilling holes, or doing very simple xy stuff I have no interest in standing at a mill cranking handles. Manual millwork brings me no joy . MOst of what I do with a mill involves curves and surfacing so that influence my opinion. If I never have to setup another rotary table again I'll be a happy man.

[RB211]

Would you want to fly airliners for a hobby? Or would you or most professional pilots gravitate more towards an ultralight or home built where everything is pilot controlled?

As someone who fits that description I think it just comes down to personal preference and they type of work you do. The things I make at home are different than at work. I don't have a need for a CNC lathe, nor would I want one. For a lot of stuff, programming a part just isn't faster than cranking the handles. Unless there is a lot of material to come off, or i'm making multiples. I just simply prefer to turn manually. IMPO it's just faster. Even at work there are lots of times I'll just run a few parts off on the hardinge, instead of firing up the Nakamura. If the QTY is under 5, and it doesn't involved threading, tapers, or curves, I'm usually faster with a manual lathe. I've been bit a couple times though when I've made 2 or 3 of something, and the customer has come back and ordered 100. That really sucks.

On the other hand give me a CNC for millwork over a manual all the time. Unless I'm drilling holes, or doing very simple xy stuff I have no interest in standing at a mill cranking handles. Manual millwork brings me no joy . MOst of what I do with a mill involves curves and surfacing so that influence my opinion. If I never have to setup another rotary table again I'll be a happy man.

I do find lathe work much more satisfying than manual milling, but CNC milling takes the cake. I like the CAD/CAM, and fine tuning it to get a nice finished part.
I can see where a hobby lathe converted to CNC could be a recipe for going bald, chasing down why it won't turn to 5 tenths accuracy.

As for flying an airliner as a hobby, I don't even want to think about them when I come home unless it is R/C or a combat flight sim. The ONLY small single engine piston airplane I have any inclination to fly anymore would be a WW2 warbird.

[mattthemuppet]

That is exactly what I am going to do on my 9x20.I recently bought one of the cheap ($120) blidgeport table feeds off fleabay.I'm going to extend the rigthand end of the lead screw and mount the table feed there.So then I will have fwd/rev and VS feeds and be able to keep the thread change gears in the most used range.

How I wish the Chinese had copied some lathe other than an Emco.

neat, I look forward to seeing the pics. If (and that's a big if) I ever get round to it, something like a 23VDC motor out of an electric scooter and a small DC motor controller would work fine. Direction is a simple DPDT switch deal and full speed (say for reversing the carriage) can be done with a momentary switch joining the 2nd and wiper wire of the variable resistor used to set speed.

To be honest though, there are so many more pressing projects in between now and this one that I'm more likely to buy a new lathe before I get round to it

[Dan Dubeau]

As for flying an airliner as a hobby, I don't even want to think about them when I come home

That's the way I feel about CAD/CAM, and CNC when I go home...... Also the reason I tend to gravitate more towards fabrication projects, and building stuff from my available "junk" pile at home. I tend to knock out my machining projects at work on breaks or stay late, and prefer to hide behind a welding hood when I'm at home.

[JCByrd24]

neat, I look forward to seeing the pics.

Here's mine. Very simple and about $50 in parts. The speed controller I got has a voltage output but it doesn't read well at low speeds, so the next step is to just add another $20 amazon tachometer to the feed rod like I did on the spindle. I made a chart in excel already that tells me what feed rod RPM I need for a given spindle speed and feed rate (in/rev) so I'm no longer guessing.

http://bbs.homeshopmachinist.net/thr...variable-speed

[Baz]

. Precision pots that were a foot in diameter, 1% and better components and they still had to be tweaked to get three place accuracy, etc.
.

Nowadays one would use a cheap pot and digitally calibrate it to 0.5%. Thanks for the idea. If I get back to my project instead of the expensive BCD encoded switch I will make a clickstop for a pot and calibrate it to act like a switch.

[skunkworks]

I think the main issue is people pick cnc software that doesn't work very well for threading... Then from that point on they think that pc based cnc suck. (they don't)

sam

current systems that seem to work with encoder threading are

Linuxcnc
acorn
Mach4 with a couple of motion controllers (pokeys and hicon?)...

[mattthemuppet]

Here's mine. Very simple and about $50 in parts. The speed controller I got has a voltage output but it doesn't read well at low speeds, so the next step is to just add another $20 amazon tachometer to the feed rod like I did on the spindle. I made a chart in excel already that tells me what feed rod RPM I need for a given spindle speed and feed rate (in/rev) so I'm no longer guessing.

http://bbs.homeshopmachinist.net/thr...variable-speed

thanks! I even remember reading that, although I had forgotten that I remembered Good to hear that those cheap all in one DC speed controls from Amazon do the job with lower power DC motors.