Messages

1651

General Mach Discussion / Re: New to DIY cnc , Looking for some guidance and advice on first CNC

« on: March 12, 2020, 11:48:41 PM »

Hi,
that is quite an impressive hardware list, ballscrews and rails all very good.

I'm a bit questionable about the Clearpath servos, they are good quality, no doubts there, but rather that they are expensive for what you get.

May I suggest you look at B2 series Delta (Taiwanense manufactured in China) or DMM (Canadian manufactured in China) as good quality brands
that won't break the bank and much more powerful for the same money.

I favor Delta servos. A 400W Delta B2 series servo and drive has 230VAC input, no power supply required....they kick arrsse! with considerably more power and control
flexibility than Clearpath's.

Craig

1652

Mach4 General Discussion / Re: Modbus ASCII Support for Mach4?

« on: March 11, 2020, 02:09:34 PM »

Hi,
as I have posted before Mach4 has ASCII Modbus.

Craig

1653

General Mach Discussion / Re: Drill chuck reference on lathe table!!!

« on: March 10, 2020, 02:05:21 PM »

Hi,
I use good quality roller plunger snap action microswitches for home switches on my mill and achieve 0.02mm or
better repeatability. Home switches and index homing are required if ou wish to do better than that.

https://nz.element14.com/honeywell/bzc-2rq18-a2/switch-basic-top-roller-plunger/dp/1525198

Craig

1654

Mach4 General Discussion / Re: Lathe Canned Cycles Wizard problem (reverse cut)

« on: March 09, 2020, 04:38:54 AM »

Hi,
I wrote this script for a specific correction I wished to apply....it would not suit what you are trying to do but the
idea is similar.

Please post some code excerpts, first some code as it comes from the wizard, and then the same code once you have manually corrected
it. Then we can see if there is a process that can be automated.

Craig

1655

General Mach Discussion / Re: Stepper motor speed varriations

« on: March 07, 2020, 09:03:52 PM »

Hi Roger,
CPR stands for counts per rev. It is usually applied to an encoder.

If an encoder has 2500 lines, it sometimes called pulses/rev or PPR then because of the quadrature placing of the opto-detectors
it will have 10,000 counts per rev or CPR.

If you set your microstepping to 1/8^th (recommended) then your steppers will rotate exactly one revolution when the drivers are presented with 1600 pulses or CPR.

Lets tackle the Z axis first. If the stepper rotates once with 1600 pulses and the z axis will advance 2mm, being the pitch of the ballscrew.
The 'steps per unit' value that you put on the Z axis tuning page will be:
StepsPerUnit=1600 / 2
=800

Easy!

Now the X and Y axes are not so simple. You say they are belts with a 24 tooth pulley? What pitch are the teeth on the belt?
For the purposes of demonstration I'm going to assume 3.15mm pitch (1/8 inch).
StepsPerUnit= 1600 (steps per motor rev) / (24 teeth x 3.15)
=21.16
You will have to round to 21 steps per unit.

Note this is very course resolution, every pulse will advance either the X or Y axes 1/21 (=0.05)mm. Is this what you expected or wanted?

Craig

1656

General Mach Discussion / Re: Stepper motor speed varriations

« on: March 07, 2020, 02:11:45 PM »

Hi,
ideally the steps per unit should be calculated but many people get confused and use a measurement approach.

It seems strange to me that even the most mathematically challenged person seems to grasp compound interest
on their loan......all without a calculator....and yet cannot get their head around 'steps per unit'.

What pitch are your ballscrews?
Do you have belt reduction from the stepper to the ballscrews? If so what is the reduction ratio?
What have you set as microstepping? If you haven't or don't understand I would recommend 8 microsteps per
fullstep or 1600 steps/rev.
What are your native units?

Tell me these numbers and I will outline how you calculate the 'steps per unit'.

Craig

1657

General Mach Discussion / Re: Stepper motor speed varriations

« on: March 07, 2020, 02:03:50 PM »

Hi,
the 'Setps per Unit' value can be calculated or measured. It is specific to your machine and unless you change your
ballscrew or belt pulleys will stay the same for the life of the machine.

Maximum speed (also called velocity) and maximum acceleration have to be arrived at by experiment. My previous
post outlines the procedure.

What you are trying to do is top establish the capabilities of your steppers/drivers and then set your maximums
WITHIN those capabilities so thy don't lose steps when operating.

Craig

1658

General Mach Discussion / Re: Setting Z height with a manual tool change

« on: March 07, 2020, 01:56:52 PM »

Hi,

So I tied into my emergency stop circuit and with a connection to the cutter and another to a 0.0015” feeler gauge.

That is no the correct way. When your machine Estops it attempts to stop instantly and it will lose steps and therefore lose
its 'reference' or 'home'.

There is a Gcode instruction especially for 'probing' called G31. for example:

G31 Z-1 F10

It is assumed that the tip of the tool is say 1/4 inch (approx.) above the feeler gauge/touch plate. The Z axis will descend
towards Z=-1 inch at 10 inches per minute UNTIL it detects a probe strike event on Machs Probe input, at which point it will
use max deceleration to stop. At that point you can use the Z axis DRO to set your Z offset.

Craig

1659

General Mach Discussion / Re: Mach3 ESS and Endurance 10W Laser

« on: March 06, 2020, 06:46:16 PM »

Hi,
the ESS uses Ethernet to connect to the PC and it generates signals which are output via the three
IDC parallel port headers. You connect an IDC cable from a parallel port header on the ESS to the
parallel input of the MB02 breakout board. There are three parallel port IDC headers on the ESS so you can
have up to three MB02 breakout boards fitted for a total of 51 inputs and outputs.

As for Mach4, i cant use it as i have purchased an Auto Tool Changer Screenset which works perfectly for my router tools and I cant use this on Mach4 so Mach3 it is for some time. 

What......and Mach4 can't handle ATC?. Rubbish.

Craig

1660

General Mach Discussion / Re: Stepper motor speed varriations

« on: March 06, 2020, 06:38:27 PM »

Hi,
OK you need to try some experiments to work out whats happening.

What are your native units? I use metric so I will assume mm units.

In the first instance you need to write and run small Gcode programs to test each axis, firstly at low speeds slowly
increasing to rapid traverses.

For example:

g1 x200 f100
x0
x200
x0
x200
x0
x200
x0

This code should cause the x axis to move back and forth by 200mm at a max of 100mm/min.
Now try the same code but at higher feed speed:

g1 x200 f200
x0
x200
x0
x200
x0

The same motion, back and forth but at 200mm/min.
And again at a higher speed:

g1 x200 f300
x0
x200........etc

Keep repeating the test but with ever increasing feed speed.

I don't know what speed max speed you have tuned your motors for, lets guess at 2000mm/min. Then the following code
tests the x axis at rapid traverse speed:

g0 x200
x0
x200
x0
x200
x0


I am guessing that if you follow this you will find an eventual limit beyond which you get the variations in speed but
below that limit the x axis behaves normally.

Try it and report back.

Craig