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  #21  
Old 09-10-2017, 10:13 AM
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Quote:
Originally Posted by miker View Post
Have you read this thread on making leadscrew nuts from Acetel/Delrin using the leadscrew as the form?

http://www.denfordata.com/bb/viewtopic.php?f=50&t=3727

Apparently it has been quite successful.

Michael
I haven't seen this article, but I have delrin nuts made for my 3D printer ans CNC mechanism (project in progress), and they are OK.
(see here.. the black thing on the table)

Recently Chinese suppliers are selling lead screws + brass nuts on ebay for ~$13... I am using them for this project, they seem to be quite good.

Last edited by bojan; 09-10-2017 at 12:25 PM.
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  #22  
Old 09-10-2017, 10:47 AM
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Originally Posted by rally View Post
Bojan,
There are many different hardening processes, the process depends entirely on the type of hardening you need and the type of material that you are hardening.......
Hi Rally,
I have no idea what kind of steel the rod is made of.
I guess I will have to take a risk and try.
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  #23  
Old 17-10-2017, 12:57 PM
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Originally Posted by bojan View Post
I was thinking...

In order to do threads on that machine, I would need to add encoder to the main shaft and stepper on the lead screw.
A processor would then move the tool in sync with chuck rotation along the axis of the thread.
The radial movement can be done manually....
No need for gears...
Someone "stole" my idea...
Doesn't' matter, It will be easier now for me to actually finish this project
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  #24  
Old 17-10-2017, 01:39 PM
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Looks good. I was thinking of doing similar, but I found a metal lathe in the council pickup (can you believe that?)
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  #25  
Old 17-10-2017, 01:44 PM
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Originally Posted by dimithri86 View Post
Looks good. I was thinking of doing similar, but I found a metal lathe in the council pickup (can you believe that?)
Yes, I can... but it never happened to me
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  #26  
Old 18-10-2017, 12:03 PM
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Firmware can be downloaded from here..
(looks like registration is required for downloading more that 3 files... so I registered)
It seems there are "lite" and commercial versions (? my Russian is a bit rusty..)..

Last edited by bojan; 18-10-2017 at 12:51 PM.
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  #27  
Old 19-10-2017, 07:36 AM
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Have you read the books by David J. Gingery?

In particular this book
https://www.amazon.com/Metal-Lathe-B.../dp/1878087010
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  #28  
Old 19-10-2017, 08:45 AM
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Quote:
Originally Posted by dimithri86 View Post
Have you read the books by David J. Gingery?

In particular this book
https://www.amazon.com/Metal-Lathe-B.../dp/1878087010
Too late for that now, the concept of my machine is already determined by what I have done so far...
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  #29  
Old 04-11-2017, 03:29 PM
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Axial motor mounted.
Unfortunately, the lead screw is double start (ebay seller's mistake)... so I am not sure if there will be enough torque, but is should be OK while I am waiting for the single start one.
I will probably finish design of radial slide compound by then as well.

Now it is time to start thinking about electronics....
I am playing with idea to use encoder instead of knobs....
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Last edited by bojan; 08-11-2017 at 12:06 PM.
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  #30  
Old 05-11-2017, 05:33 PM
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the Cryobi drill press is only just recognisable....

A question....what did you do with the red light centreing thingy and switch?

I have an idea to use them as illuminators for setting circles on my old mount.

I have one from my drill press....care to donate the other one, for a small consideration of course

Matt
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  #31  
Old 07-11-2017, 05:12 PM
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Matt,
the "thingy" is actually 6mm laser with diffraction "cross generator", focused at ~20cm from lens.
Unfortunately, I already used it for my 3D printer alignment.

However, those things are easy to get on ebay ... This one is line only (possibly better for your application), but if you want cross, look here.
They are both powered by 2xAAA, 3V
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  #32  
Old 08-11-2017, 02:39 PM
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Today I tried to compile the arduino sketch (By Oleg)
(the link may not work... so I translated some comments and attached the archive).

After some initial troubles with errors ("not defined in current scope" etc.) fixed (probably) by adding couple of libraries, the code compiles OK.

This firmware version (7a_lite) supports handle encoder (one knob for both axis, switchable by selector switch), limit switches, adjustable feed rate (pot), thread cutting (this works with chuck encoder)... almost everything I may ever needed (or so I think at the moment).
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  #33  
Old 20-11-2017, 07:24 AM
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While waiting for keypad/LCD board to arrive, I was thinking to temporary use Digispark board as quadrature decoder (conversion of encoder output to STEP/DIR).
While I know that this is not really needed (because encoder could be connected directly to STEP/DIR inputs of the Pololu driver (of course, the back/forward transitions of STEP could be interpreted as continuous movement in one direction, but it is not the real issue here), my reason for using this $2 board is the 5V regulator, needed for optical encoder power supply (Oak-Grisby).

I found an interesting code for controlling the intensity of LED (tried it, works on Digispark after changing the port for LED). The idea is to replace the "analogWrite" function with STEP/DIR pulse outputs (1us duration)...

If I try hard enough, I will probably do it myself but... it may be easier if someone could point me to suitable piece of code? Thanks in advance!

EDIT:

This code is tested and works OK, output is DIR and PULSE at each interrupt (5 usec duration), depending on encoder movement direction.


******************************
#include "avr/interrupt.h";

volatile int lastEncoded = 0;

void setup()
{
pinMode(0, OUTPUT); // DIR
pinMode(1, OUTPUT); // STEP, on-board LED

// set pins 3 and 4 to input
pinMode(3, INPUT);
pinMode(4, INPUT);
digitalWrite(3, HIGH); // and enable pullup resisters
digitalWrite(4, HIGH);

digitalWrite(0, LOW);
digitalWrite(1, LOW);


GIMSK = 0b00100000; // Enable pin change interrupts
PCMSK = 0b00011000; // Enable pin change interrupt for PB3 and PB4
sei(); // Turn on interrupts
}

void loop()
{
}


// This is the ISR that is called on each interrupt
// Taken from http://bildr.org/2012/08/rotary-encoder-arduino/


ISR(PCINT0_vect)
{
int MSB = digitalRead(3); //MSB = most significant bit
int LSB = digitalRead(4); //LSB = least significant bit

int encoded = (MSB << 1) |LSB; //converting the 2 pin value to single number
int sum = (lastEncoded << 2) | encoded; //adding it to the previous encoded value

if(sum == 0b1101 || sum == 0b0100 || sum == 0b0010 || sum == 0b1011)

digitalWrite(0, HIGH); // Direction forward

if(sum == 0b1110 || sum == 0b0111 || sum == 0b0001 || sum == 0b1000)

digitalWrite(0, LOW); // Direction backwards

// Pulse after delay
delayMicroseconds(5);
digitalWrite(1, HIGH);
delayMicroseconds(5);
digitalWrite(1, LOW);

lastEncoded = encoded; //store this value for next time
}

EDIT 2:

I stumbled on un-expected hardware problem with Digispark Attiny board - because of protection zener diodes on USB connector (marked as 'W4', supposedly 3.6V), input voltage levels from encoder were around 2.5V only - so the whole thing worked very erratically at 5V due to the noise from Pololu drivers. After I removed those diodes ( I think they were not really needed, they were placed "just in case" and they were obviously not 3.6V as marked in some schematics found on web), the circuit worked as expected.

Last edited by bojan; 23-11-2017 at 08:13 AM.
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  #34  
Old 31-05-2018, 12:13 PM
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Work on my lathe is progressing, now I have both axis properly assempled and equipped with stepper motors.


The web search for firmware and PC application resulted in this project, lathe is controlled by GrblGru.


Is there anything else/better available? GbrlGru simulation is behaving strangely when I imported very simple LibreCAD drawing (dxf), the 3D model looked OK on the screen but the tool movement would damage my machine in reality.
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  #35  
Old 03-06-2018, 04:16 PM
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Tried today om my workbench..


All works OK.
All I have to do now is to put back motors on lathe...


And perhaps to build joystick & controller, to have a lathe independent of PC or laptop.
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  #36  
Old 03-06-2018, 04:50 PM
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I love the industrial chunk and heft of your modification - Well done Bojan

Best
JA
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  #37  
Old 03-06-2018, 08:13 PM
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Thank you :-)
I tried to make the design no-nonsense & simple, using available standard materials (aluminium extrusions, standard bolts), parts from my drawers and minimal modifications to achieve required functionality. The whole thing works, that's important.

Last edited by bojan; 04-06-2018 at 11:48 AM.
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  #38  
Old 04-06-2018, 04:45 PM
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Re joystick...

I found this webpage...
The code works as it should, now I have to modify it according to this page and/or to this page to generate jog commands for grbl controller, for lathe movement to be independent of laptop.
Also need to mount verniers.

Last edited by bojan; 05-06-2018 at 06:52 PM.
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  #39  
Old 16-06-2018, 02:12 PM
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It's working....


The calipers are $10 each from ebay... nor stainless neither hardened (well, it is some hard aluminium alloy or "white brass" (it behaves like brass when filing, and it was cast).. so the printing on them is not totally false).


Cross slide one is positioned a bit too high (so it may be in a way of tool in some cases), and of course it indicates radius, not diameter.
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Last edited by bojan; 17-06-2018 at 07:50 AM.
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  #40  
Old 02-12-2018, 11:57 AM
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Finally, it is complete (almost).
Controlled with GRBL (Arduino-Uno) + another Arduino Nano which reads hand encoder and switches on front panel and sedns commands to GRBL via serial interface.
This way, I have full manual control of the machine, but if I need to execute program, this is possible by connecting computer/laptop via USB.
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