Messages

3371

General Mach Discussion / Re: homing for probe

« on: August 18, 2011, 05:01:49 AM »

How do I set up a limit switch to use to zero a grinding wheel?

Have never done what you are asking. I always dress my grinding wheel before using it ....don't you?
I have a Sanford bench top surface grinder which is totaly manual so you measure as work progress.
It would seem that the tip or high point of the diamond would be a better reference  relative to the face / bottom / side of the wheel.
That can be used to trip a switch or whatever. Since you only grind in tenths ( .0001") at a time you will need a very accurate and repeatable
switch. What the surface being ground relative to the wheel or wheel wear rate is as your grinding is another story.

I only remember one thread  on a grinding machine trying to use Mach a long time ago.

Someone who does surface grinding at the comercial level can probably be of more assistance.
FWIW,
RICH

3372

Show"N"Tell ( What you have made with your CNC machine.) / Re: Using Biodiesel as a machining fliud - Video

« on: August 17, 2011, 06:42:35 AM »

I always use a fan in my workshop to blow the smoke away from me when cutting.  I used to use expensive Rocol cutting oil for heavy cuts in my manual lathe and it gives off  similar amounts of very obnoxious smoke.

That is just about the worst thing you could do - stir up the air, mixing in any toxic particles from the diesel (which are seldom visible)   
A better solution may be an extractor system.

You need an agent, ingnition source, and oxygen. There is a low and high level of ignition and also the enviroment condition comes into play.
Pop just didn't have the right condition. Didn't mom ever tell you that if you play with matches you'll get burnt! 

RICH

3373

General Mach Discussion / Re: X and Y distances not tracking the DRO setting

« on: August 17, 2011, 06:26:35 AM »

It asks how far to move ...22"
It then asks how far did it move ....21.9"
It then gives you  a steps per value ....can accept or reject the value, if accepted it will change the value in motor tuning.
Now with the new & saved steps per value, you do it again for the same distance /22" .....it may be spot on or off some, but very close.
Quickly you will get the correct steps for that distance. It may take more than one or two tries at that distance.
It is just doing a ratio on the steps same as if you were doing it maualy. If there was backlash or the axis is non linear,ie; a screws pitch is gaining or decreasing,a non repeatable axis ,then then you will go into a never ending loop of trying to calibrate, you get close but never exact.

Your steps per can be no better than the resolution of the axis, so as you approach that....and no axis is perfect, you will fall within some range of steps per unit value, only you can pick the value which will be used. Maybe a better way of saying it is, you can calibrate to some degree of accuracy; isay .001" and trying to find the steps per for say .0001" is fruitless / your wasteing your tme because the system just can't provide for it.

Summary: You can quickly get to a usable steps per unit value and refining to a value beyond the machines capability or  your measuring capability
               is useless.

BTW, if one changes the steps per unit value, make sure you save your settings, get out of Mach and go back in and make sure the value was
changed.

RICH
       

3374

LazyCam (Beta) / Re: Foam 2D with X Y Z A hot wire

« on: August 16, 2011, 05:40:09 PM »

Edu,
Lazycam is the way it is and is no longer being developed so your on your owne.
Don't have the foggiest idea on how to change LC's post processor.

RICH

3375

General Mach Discussion / Re: X and Y distances not tracking the DRO setting

« on: August 16, 2011, 05:23:58 PM »

Greg,
Sorry, but should have been more clear in my reply.....do as BR549 replied....assumed you would not do what you did.
RICH

3376

General Mach Discussion / Re: X and Y distances not tracking the DRO setting

« on: August 15, 2011, 09:55:59 PM »

Keep it simple. Just calibrate for the longest distance and after you have found an appropriate velocity and accel, then maybe profile the axis.
You take out any backlash, move in say even movements and check the positioning and plot them if so desired.
The moves could be 6@4", 12 @2", even 24@1". For me it's easy as I do it opticaly. That will tell you what to expect from the axis in terms of accuracy.

RICH

3377

General Mach Discussion / Re: X and Y distances not tracking the DRO setting

« on: August 15, 2011, 08:54:46 PM »

Start by making sure you steps per are correct.
See what they are for a long move say 24", use the axis  calibration feature. Set a reasonable velocity / slower than normal ...say 50% of your max and see if the axis is repeatable. After that, check steps for a 12" and 6" move. Since you calibrated the steps based on the longest run, any error  will be small at the lesser moved distances.
If all if fine for steps per units, now play with the velocity and accel to see where an axis will skip, lower the velocity to say 60 0r 70% of max and then play with accel in a similar fashion.

RICH

3378

General Mach Discussion / Re: machine power question

« on: August 15, 2011, 06:17:21 AM »

Most motors are rated by holding torque lb-in / in -lb or Nm. So  16kgf.cm dosen't relate well in my mind offhand.
150 MPA ?

How much HP is required to machine a material can be calculated ( value calculated is not exact ) and depends on spindle speed, feedrate ,depth of cut and machinability of the material. The mechanical aspects of the axis also plays into the above.

Then you also have the characteristics of the material due to  machining ie; some may work harden.

Nothing beats some experience so just try cutting some  similar material and see what it can do.

RICH

 

3379

General Mach Discussion / Re: Noisy Steppers when stationary

« on: August 15, 2011, 06:02:37 AM »

What i am guessing is that you have a switch on the driver for current reduction and when the motors are stationary it reduces the current to the motor.
The motor then dosen't have adequate  holding torque ie; it sort of just sits there trying  to maintain postion  and thus oscilates.
Said a different way the electrical field is not strong enough to hold the rotor in one position relative to the winding.

Could be wrong but that is the only time I experienced some noise coming from a stepper sitting idle.

RICH

3380

General Mach Discussion / Re: Motors won't turn

« on: August 15, 2011, 05:42:14 AM »

When you open Mach is the Reset button flashing ? if so click it.
RICH