Messages

21

Newfangled Solutions Mach3 Wizards / Re: Surface Material Wizard - bug - odd values

« on: February 19, 2011, 06:15:30 PM »

Sage,
What you are seeing is round off error, The first depth of cut is -0.0067 or approximately (-0.0200/3). The right value should have been -0.006666666666.... The second value is 2 X  0.0067 = -0.0134, and the third is 3 x 0.0067 yielding 0.0201.

The height of 0.1 is the safe-move height for Y axis movement.

The algorithm could have been a little more careful, but an error of 0.0001 is probably outside the precision of your machine (or at least the program designer's machine). Best thing to do is adjust the final value manually if it is really important.

This is precisely why you double check the code on every project.

Thanks,
Bill

22

General Mach Discussion / Re: Re-starting on a partially cut piece of material

« on: February 19, 2011, 01:34:06 PM »

You really have a small number of choices to solve your problem. Because you did not plan for this eventuality, you must rely on 'poke and hope'  by moving the tool over the partially finished work until you feel satisfied with the alignment. You can do trial cuts on overlay stock. There are lots of tricks you can invent to get satisfactory results.  

To plan ahead for disaster recovery, you need to have either:
A) two reference edges that you can keep until your final cut (easy to do).  
B) a reference edge and a reference hole (easy to do). The edge gives you angular alignment and the hole gives you offset to 0,0.
C) two reference holes (harder to do)

I have recently begun to use the reference edge and the reference hole as the easiest practice to use, and it has saved my butt several times.

You also need a dial gauge, that can be easily mounted on the Z-Axis, for any reasonable accuracy in the repeat finding the reference to the X and Y axis. Your eye or a ruler is simply not good enough.

Mach 3 has an edge finder input that is incredibly nice, especially for finding the center of a hole. I made and use an aluminum corner finder that allows me to find the edge (0,0) on a rough or rounded corner reliably. It will allow me to find the corner either by the hole method or the edge method on both metallic or nonmetallic stock. It has two holes, one over the 0,0 of the corner, and the other at 0.5, 0.5 from the corner. If you don't use the Mach3 edge finder feature, then set it up and use it. You will love it.

I have created several macros (various 0,0 finder routines using either edges or holes)  that I can drop into my g-code programs that allow me to preset the reference every time I run the job.  Now each job has built in disaster recovery. As long as I don't move the work piece, I only need to find 0,0.

good luck,
Bill

23

General Mach Discussion / Re: Voltmeter

« on: February 01, 2011, 07:15:02 PM »

The probe wires must be soldered to the probe tips to be of any value whatsoever.  Glue and tape are useless patches.
With that said, to solder them, you must be able to disassemble the tip from the plastic handle. Some tips are screwed into the plastic some are press-fit. The repaired wire must run through the plastic handle for best results.
It may be significantly easier to buy new probe leads.
Some meters are so inexpensive, that buying a whole new meter may be your best bet.

Thanks,
Bill

24

VB and the development of wizards / macro embedded in Gcode regens toolpath at 0,0

« on: January 31, 2011, 10:06:19 PM »

I recently created a VB wizard/macro that I intend to call from G-code.

I get the current X,Y, & Z location from GETOEMDRO().
I pass the necessary pattern information through P, Q, & R parameters.

In the g-Code, I position the tool at the macro starting location and then call the macro with the appropriate runtime parameters in P, Q, & R.
When I load the program, the macro's toolpath result is generated on the toolpath screen at current DRO location instead of where it is supposed to be. Because I call it several times in the g-code, all of the cutouts appear to be on top of each other (not pretty).

When I run the code, it appears to cut and display at the proper location (This is good).

Is this normal?  If not, what can I do to correct it?

Thanks,
Bill

25

VB and the development of wizards / Re: Read All !!! Stupid Save Function

« on: January 17, 2011, 09:00:26 PM »

Been there too. Been burned a couple of times. Perhaps it needs to either auto-load the macro, or not remember the name. As you say always "save as"

The other thing I would like is for it to have its own directory pointer. It shares the one from 'Load G-code' which is not even close to my macro directory.
 
The editor could add line feeds to make it more compatible with notepad. (Nice that WORD will put them back in.)

It does recognize "else if" but does not highlight it like a true command

Also if you test it and it has an operator input, you can't stop it without a break-point.

Always make a backup copy. Always. Always.

Thanks,
Bill

26

General Mach Discussion / Re: TTL signal

« on: January 08, 2011, 04:57:08 PM »

A real easy to configure solution for your tiny project board.

A simple PNP transistor will do just fine. ... wire the emitter to Plus 5 Volts, the collector to the laser input control, and the base to the port output through a 1000 ohm resistor. Also wire a 1000 ohm ohm resistor between the base and emitter to guarantee a clean turn-off

The transistor will pull to a firm VCC minus 0.3 volts.

Don't forget to set the turn on logic to low= ON

The transistor should be rated at about 100 ma collector current. The resistor values aren't critical and you could use values up to 10,000 ohms without consequence.

Good luck,
Bill

27

General Mach Discussion / Re: Setting up safe limit switches

« on: December 12, 2010, 11:12:59 PM »

Jim,
I forgot two things.
1) Your driver board may not need the resistor (mine requires it). The photo of the board appears to show that the inputs are optically isolated, this means that the resistor is probably built in. You can check this by checking the voltage on the input pin with respect to the ground pin. If it reads above 4 Volts it is in there. If you add one anyway, it should not hurt anything. (Another clue that it is in there is that the connector diagram does not show a plus 5Volts available on it for connection).

2) On the Settings screen, turn ON "Auto Limit OverRide". This allows you to reset the E-stop and move off of the limit switch with manual motion control (arrow keys). 

Good luck,
Bill

28

General Mach Discussion / Re: Setting up safe limit switches

« on: December 11, 2010, 09:59:25 PM »

Jim,
1 ) Mount the switches. You may want to wire them before mounting them. Choose the wiring path carefully.

2 ) Connect the three home limit switches in series (X-NC to Y-C, Y-NC to Z-C) using the switch common (C) and the switch normally closed contact (NC).

3 ) The remaining X-C and Z-NC terminals will be wired to the input port. Nothing will be connected to the normally open (NO) contacts.

If you have a multimeter, use the ohms or continuity setting, test each switch and the three switches wired in series. The two wires coming from the switches to the port should appear shorted until you press any of the three switches. Then they should indicate an open.

4 ) Wire the switch X-C wire to the port ground.

5 ) Wire the switch Z-NC switch wire to one of the inputs. The input should be set-up for stopping all three axe (X, Y, & Z) with a positive signal.

6 ) Now get a 4,700 ohm (1/8 watt or 1/4watt) resistor. Any resistor value from 500 ohms to 20,000 ohms will work just fine. Lower ohms draws more current, and higher ohms allows more sensitivity to noise. If you need to buy one fast, Radio Shack has them locally for under $2. for a set of 5.

7) Connect the resistor between the switch input port (Z-NC) and the Plus 5 volt supply.

8 ) Monitor the port on the diagnostic screen, it should indicate that the port is at ground. When you activate any of the switches, it should go to plus 5 Volts and turn on the port indicator, as well as E-stop the machine.  

9 ) If any of the daisy-chained switches or any of the wires are defective, the circuit will open and do an E-Stop.

10 ) Set the software de-bounce timing so that the switches do not trip under normal use from vibration. (try 200 & 100)

Hope this helps,
Bill

29

General Mach Discussion / no safe Z in local system rotated

« on: December 05, 2010, 10:44:02 AM »

Yesterday, I had the opportunity to take advantage of the LOCAL SYSTEM ROTATED feature as offered on the MDI screen. I rotated to 180 deg. To my surprise and to the breaking of a tool, both the STOP and GO-TO-ZERO functions did not use SAFE Z. After double checking the safe Z status, I confirmed that the Z axis did not change from its current position when using either of these functions.  After rotating back to 0.00  degrees, operation returned to normal. I did not try any other angle. 

Is this the correct operation? I am using the latest locked-down version (Mach3 R3.042.040)

Thanks, Bill

30

General Mach Discussion / Re: tool force compensation

« on: December 04, 2010, 08:15:10 PM »

Hi all,
I use my CNC machine for mostly cutting relatively thin (0.050" to 0.100") aluminum face-plates for electronic equipment. My tool of choice is 0.093". I rarely use the CNC for straight drilling. However now and then I cut thicker 6061 aluminum. Attached is a picture of a bearing block I just cut that will be used to replace the Delrin blocks of the same shape on this machine. One is 0.625" thick and the other is 0.75" thick. I am hoping that these will add a modicum stiffness to the gantry system. I find that the plastic blocks keeps relaxing and needs frequent adjustment. The CNC machine has trouble cutting a piece of material this thick without some drift. The latest blocks were cut reversing the cut direction on each pass (a new experimental technique for me), at a cut depth of 0.008, and I had very good results. The blocks are about 0.005 over sized as a result of tool not holding the desired path. These parts don't need to be any closer than that so I am pleased with them. Had I cut these in only one direction, they would be a good 0.025 over or under depending on the cut direction and exhibit a some taper.  

I am in the process of replacing the wooden parts with aluminum stock, in the mean time I would like to try to compensate for the flexing that the wood permits. I just hope I don't have to replace the steppers to push the extra weight after it is all modified.  

I haven't tried the function routines yet, but I will get around to it some day soon. This is not my day job.
I appreciate all of your input on this matter.

Thanks, Bill