Messages

5891

Show"N"Tell ( Your Machines) / Re: The Laser Project.

« on: August 04, 2011, 02:37:26 AM »

Hi naPS,

That's great news that you have it all running OK so where are these pictures then ?? 

Tweakie.

5892

General Mach Discussion / Re: G31 Probe problem

« on: August 04, 2011, 02:30:40 AM »

Hi Guys,

So, should we be using the Sleep() command within the while...wend or not ??

Tweakie.

5893

General Mach Discussion / Re: New people welcome !! Come in here and introduce your self!

« on: August 04, 2011, 02:14:08 AM »

I wish if a day was mach's day in a year, when all the cnc jerks could enjoy some beer together somewhere (some could have scotch also)

jasminder singh

The Beer would suit me just fine 

Welcome to the forum guys  ( I think Tricky Dicky must be on holiday at the moment ).

Tweakie.

5894

General Mach Discussion / Re: Caps on inputs

« on: August 04, 2011, 02:07:08 AM »

I haven't had any noise problem with my CNC machine, but I used to race RC cars, and we put caps from the positive motor input to the motor can, from the negative motor input to the motor can, and from the positive input across to the negative input.  (strictly DC battery power to the motor)

This completely did away with noise from the motor, don't know enough about steppers and driver boards to know if that would work or not.

Jim,

You are quite right about the brush type RC car motors but Stepper Motors are different in some quite important ways. During operation the bipolar type motors have current reversal through their windings and although the magnetic field has to collapse and re-establish - to ensure that steps are not missed, this usually happens within 2nS. Fitting any capacitors to the motors will compromise this timing and could totally destroy performance - It may also cause damage to the motor driver circuit.

(Bit of a co-incidence really, but yesterday I was measuring current reversal times in 20 differently constructed coil types to establish the so called 'point of stall' when driving solenoids and relays from bipolar stepper motor drive circuits).

Tweakie.

5895

General Mach Discussion / Re: Axis reversed??

« on: August 03, 2011, 11:45:54 AM »

Hi Rikk,

I was going to tell you that but I thought Hood would have got there before I finished typing 
(perhaps he has taken the afternoon off and gone fishing ?)

Tweakie.

5896

General Mach Discussion / Re: G31 Probe problem

« on: August 03, 2011, 08:21:07 AM »

Hi Guys,

Mind if I add my 2 cents.

I don't know why we do it but we always seem to keep our broken probe tips, perhaps it is to teach us a lesson or so we don't forget. 

Anyway, i can't remember which Mach revision started it all but since then every Macro / Script needs a "while.....wend" between every write and every check to keep the CE speed  in line with Mach execution. As Ian has said, without it the code will be unpredictable (work just fine on one machine but not on another and even then you can't count on it).

I have a sneaky suspicion that when we all eventually agree on this - Version 4 will come along and change everything. 

Tweakie.

5897

General Mach Discussion / Re: Caps on inputs

« on: August 03, 2011, 07:58:57 AM »

Not sure about this statement.
 

We had some estop/limit issues a while back and put a .1uF cap on the estop input. But we also put them on the motor inputs as well for X, Y, and Z.

I really don't think you should be putting caps across your motor inputs (unless that is a recommendation by the boards manufacturers).

In my opinion the estop cap should connect between the input pin and GND.

Tweakie.

5898

General Mach Discussion / Re: Switches behave strangely

« on: August 03, 2011, 06:41:34 AM »

Isaac,

You would be wise to use twin core shielded cable to connect your switches with the shield connected to GND at the breakout board / controller end only.
The 0.1uF capacitors that Hood mentioned connect between the switch input and GND , again at the breakout board / controller end.

Tweakie.

5899

General Mach Discussion / Re: Caps on inputs

« on: August 03, 2011, 02:51:30 AM »

The 0.1uF caps are used for the reduction / elimination of electrical noise on the switch inputs and are connected between the appropriate pin and GND.
It is not a good idea to fit them on the step and direction pin inputs.

Tweakie.

5900

General Mach Discussion / Re: Current Hi/Lo setting?

« on: August 03, 2011, 02:40:53 AM »

Keith,

You may find the info presented here of interest  http://www.savebase.com/infobase/downloads/TB6560/TB6560_4Axis_Driver.doc

(the RepRap is wired differently to any CNC router and so has different pin assignments)

Tweakie.