Hello Guest it is April 17, 2024, 08:09:51 AM

Show Posts

This section allows you to view all posts made by this member. Note that you can only see posts made in areas you currently have access to.


Messages - vinythewheel

Pages: 1 2 »
1
of course, but i have the spindle position with a 4000 count encoder.

2
When i look to your 4 first page of you document (Probe trigger point cosin error pictures.pdf) it's clear that if you probe a inclined surface you can't know the position of the surface. You have to probe two points and calculate the surface slope, find the perpendicular verctor direction then you can calculate the real position of the surface in reference to the probe tip center. This calculation look like the one used when you want to make 5axis tengential machining and need a bunch of man time to implement.

In the case of a the folowing mesurement :
-rectangular pocket aligned in the XY plane
-Edge aligned in the XY plane
 The first two page of your document dont aply

In the case of a circular pocket, the fist 4 page dont aply also cause you recenter the probe in the center to mesure the other axe. thea way, the probe movement is alway perpendicular to the touched surface.

Eaven if you want to digitalise a point cloud of a complex 3D surface, i think the algorithme present on the mach3 webpage take care of cosine error (not shure, never try them). If your probe is off-center, you only have to take the point cloud and translate it the amout of probe ofset in the X and Y direction. and the result will be correct.



The last page of your document represent the problem that can be solved by the routine i propose. (post #39 to #41). With this kind of routine, you can increase the acuracy of the probe positioning operation for a edge probing and pocket center finding.

When i want to zero of my part on the center of a hole i do this operation.
-Install the probe
-mesure my reference hole wich are at a know position (360, 270)
-take the mesured result (360.05, 269,93)
-calculate the position of the ball (360.05-360=0.05  and 269.93-270=-0.07)
-mesure the hole on my part where i want to zero mach3
-after mesurement, the probe go to the center of the hole a zero the XY axis
-edit the X axis DRO and put the value of 0.05
-Edit the Y axis DRO and put the value of -0.07
-hit a G0 X0 Y0
-place a edge finder in the spindle and verify the position of the spindle in reference to the hole.
-Good place all the time

This routine can be automated easily within the MSM app. I can implement it if you can add couple of DRO in your setting page tha i can use.

Thank a lot for your interest

3
In the tab "Probe only" it will be greate if you add a button for hole center. It's hapen often that i want to know the distance betwen two hole center. It's very hard to mesure it with conventional mesuring tool. Probing is the way to do it, i think...


Another thing,
my probe tip is a perfect sphere so i dont anderstand your argumentation about " It also seems to only address probes along the X and Y axis." if the position of the sphere is know in the machine coordinate system, there is no possible problem. Knowing the z position is easy and dont move that much if the probe get fiew mill ofset in the XY plane. If you probe in the referenced circular pocket (with a know position), you find the position of the probe tip (sphere) in the machine cordinate system. Then any probing operation can be corected easily with the know ofset. eaven if the probing operation is in diagonal.

Please excuse my poor englich.

A probe can be aligned but one secon is needed to bend the stylus without knowing. this cause problem for finding a edge on a part and cause mill operation error. I still think it will be e very good idea to add up those functionality to the interface. For me and for a bunch of user.

I have good programing skill, maybe i can help on that.

Thank for your fast reply




4
i experience some problem with your screen.
i use a canadian french computer. So, the default marker for digit is "," instead of ".".
When i edit the tool table, the numeric value in the pop up window use ",". To be able to save my entry, i have to change them all to "."
and i have to do it each time.

I think you have to modify your code to take care of this isue.

Over all, this screen is amasing.
Thanks.


Other thing,
My probe dont have any possible adjustment. Si the probe is alway off center. To take care of this, i mill a round pocket on my mill table. This pocket is at a know location in the machine reference system. So when i put the prob in, i mesure the center of this pocket. The mesured position of the pocket minus the theorical mesurement of the pocket give me the actual offset of the probe. This way, when i probe a part, i just have to remove the value calculated to know the real position of the part.

To take care of this, i propose to:
-add two value in the screen to enter the real position of the pocket.
-Add a new button in the probing page to mesure the center of this pocket for probe refference purpose.
-Then, each time i probe a part in a specific direction, take care of the compensation for the probe offset.


Other thing.
When i probe a pocket or a edge, is not alway to zero it. Often it's because i want to mesure it in reference with another feature. So i propose to add a button to tell mach that i want to zero or not.


5
CVI MachStdMill (MSM) / Re: question re compensating for probe offset
« on: November 07, 2013, 11:08:58 PM »
my problem is that I bought the probe at 199$ on eBay and there is no way to calibrate it. pain in the ass. while measuring a 123 block I can calculate the ball diameter easily. if I want to know hole diameter, even with a offset probe, I will get it acuratly. but if I want to know where is the hole center or the edge of my part, there is only one way: touche the part, then turn the spindle 180°, then touch again. the average of the two position will be the position of the edge. fortunately, my spindle motor is a brushless servo DC motor with step and Dir drive. so implementing your probe code will be very useful to me. of course I know that very few guy have servo on they spindle. so its a lot of work for few customer.
if I edit the but on in your probing wizard. is there a way to call the same code twice and print or use the average?

6
CVI MachStdMill (MSM) / question re compensating for probe offset
« on: November 04, 2013, 08:51:00 AM »
Is that possible to edit probing button?
For example:
I want to find the center of a circle. If i want good accuracy, i have to find the circle once then turn the spindle 180 degre and find center again. The résulting real center is the average of both mesurement. That way, all error introduce by the ecentricity of the probe, the TIR of my spindle, ... are wiped off.

To be able to do it, i have to modify the probing macro. Is that possible?

7
General Mach Discussion / Re: Lost step on large gcode program
« on: November 30, 2011, 09:56:29 PM »
One step on the motor is 1/200 of a rotation. I now have a problem where i lose 0,2mm. 0,2mm is 0,0254 turn. On a 1 in diameter plate, this error represents 2mm. This error can be easily identified with this system. One step is 0,4mm (0,015in) on this diameter. So it's still easy to find a lost step. I actually run my Gecko at 10 micro steps per step. This system is not intended to find 1/10 on a step but something like 8 full steps or 80 micro steps.
I use an encoder on the Z axis. Those little things have a cost of 150$. I don’t really want to buy some for the other axis. In fact, if mach3 have the possibility to resolve position with encoder feedback, I buy 2 more right away.
I don’t compare the encoder with the metal plate. I use the metal plate to verify the home position only. The plate and the motor have only one mark. If the axes stay stiff, when you home the axis again, the mark should align. I do this only to remove the option of axis slip to help resolve the lost step problem.

8
General Mach Discussion / Lost step on large gcode program
« on: November 29, 2011, 10:25:36 PM »
I have a lost step issue (or gained step) that I can solve. I spend 40 hours on the past two weeks to try to resolve this issue and i just return to the point I was at the beginning. I have no more idea and need help and idea from anyone who want to help.
I discover this problem when I want to mill a plastic mould during the finishing passes. The Gcode get 1:30h to finish at 300mm/min (12in/min) feed rate (30000 lines). The offset at the end on the Z axis was around 0.8mm (0.031in). So i scrap the job and do it again with slower feed rate. Results were worst.


Thing I already done:
To verify the integrity of the mechanical line in the axes, I just glue a metal plate on the rear shaft of the motor, then I home the axe and mark with a razor blade the position. Each time I home the axe, the mark on the metal plate and the motor must be aligned. That tells me that there is no mechanical movement in the coupling and no backlash in the ball screw. It’s also a good way to verify lost step because it’s independent of any raise in temperature that can occur in the ball screw that can make the axe move. I glue those plates two week ago and after several hours of machine run, the marks are still aligned.
To measure the lost step, I home the machine then I switch in jog mode with a fine step (0.001mm or 0,00004in) a normal step on my stepper motor is 0.025mm (0,001in) so this jog step is much smaller than my motor step. I then jog till the home switch led light on and read the displacement. After homing, the out-of-phase is always between 0,0400mm and 0,0425mm every time I do it. This difference is due to the time that mach3 and motor take to react when the home switch is trigged. Base on that, I run a G-Code program and after that run, I jog to the home switch to measure the out-of-phase in machine coordinate.
I put an encoder with 1000 ppr on the Z axe. This encoder gives me exactly the same amount of step lost that the homing method give me.
I first thought of PP problem, I read a lot of post on that forum. I find someone who has a similar problem which gets solved by the SmootStepper PP replacement.  It was the easiest way and less time consuming way to fix the problem. So I bought a SmoothSteper board.
 The SS didn’t solve my problem. But that helps on the general operation of the milling. All axes run smoother and the spindle can run at 1 RPM very smoothly. It’s a great board for all this.
Then I extract the 600pound milling from its hole and open the control panel. I re-wire the control of the drive. I use coaxial wire with the shield ground on the SS casing only. The SS casing is an aluminum casing which is supposed to be a good Faraday shield. I didn’t put those wires into the wire tray to maximise the distance between those wires and the power line. The minimum distance is around 4in and there is no parallel path between the controls wire and the power line. Base on the fact that the Stepper Gecko drive can have ripple voltage of 600V, the induction on in the control wire must be less than 0.5 V in the worst case scenario. The USB cables pass in the tray, I think that the communication protocol in USB removes the induction problem that can occur in the USB cable itself.  I speak with a colleague who have 40 year in the RF industry and know A LOT about induced noise. He tell me that a low frequency noise (<100 kHz) is the more difficult noise to get rid of with shielding. Special shielding material must be used. He also tells me that the coaxial cable I used will surely remove around 20 dB of noise which must be enough to solve my problem. 
All this work to remove noise didn’t solve the lost step problem.
I then wrote down a GCode who dig a square pocket inclined at 30 degree around the z axis. The step down is 0.05mm (0.002in) and the dimensions are 100mm x 100mm (4in x 4in) at federate of 600mm/min (24in/min) I toke 20 minutes to complete the run. The axe Z home exactly at the same place each time because there is no that much move in the Z axis. But the X and Y axes always home with an out-of-phase (or lost step) of about 0.05 for X and 0.07 for Y. If I run this code several time, I always get the same results. If I run this test at 1200mm/min (48in/min) feed rate, there is no lost step. If I run this test at 100mm/min (4in/min) the resulting lag get worst. Running those test without spindle give the exact same results. In constant velocity mode, the pattern is similar but the out-of-phase values are different. Increasing the pulse width in the motor turning screen didn’t change the results.
So I get lost. Is someone having an idea to solve this issue?
I think its will be a good idea to wrote down a macro who run the same pocket GCode over and over, record the out-of-phase into a file then change something like feed rate and run the gcode again. This program can get statistic result on a specific run and may be very useful to resolve lost step issue. I try to make a gcode who move down a little, stop and move down a little a couple of thousand time. The point of this code was to be able to know if I lose or gain step. But when I run this code, I home at the exact same position. If someone have an idea to create a gcode who can do this kind of work.
PLEASSE HELPPPPP 

9
SmoothStepper USB / Re: SmoothStepper and PLC with Modbus
« on: November 24, 2011, 10:22:55 AM »
Good, i finaly redo the config and realise that i have some problem in the modbus config. Estop, limit, all working fine.
Now i want to make solid threding with my servi spindle and have couple of question.
The spindle is a Parker brushless servo motor with his drive.
I use Step and Dir to command the drive via the pin 9 and 14 on the port 1 on the SS board
I get feedback from the drive on the diférential input port 3 on the SS
Feedback is has the form of A-B encoder.
I set the encoder 1 to map the port 3 pin 4 and 5 from de SS in Port and pin mach config.
I try to set the index pulse to port 3 pin 4 and 5 but the encoder has 1000 pulse per turn and DRO RPM show a way to high speed
But then, im a bit confuse.
How can i use this encoder to show the actual speed on the DRO RPM.
How can i use this encoder to control the pid loop for spindle feedback?
Do i need feedback loop to make solid threading?

Thanls in advance

10
SmoothStepper USB / Re: SmoothStepper and PLC with Modbus
« on: November 22, 2011, 10:07:57 PM »
I have no delay problem with the limit switch, eache time i run the machine full speed into the limit, i don't crash. The main reason is that the limit trig a Estop.
The Estop shut down all drive directly and aply brake on the spindle with a releay who is normaly open. If we talk security, i think it's a again law and security principle of machine to not have a estop wiered like this. If worker use the machine and an accident occure, the worker security agency (CSST in Canada) will make an big investigation and close the shop. I mean if it's a small shop who can't pay the several k$ penalty. Im not realy sure about all this but...

So what you think about those sentence? i am right?

Pages: 1 2 »