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Author Topic: G31 probing via array macro.  (Read 26536 times)

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Re: Lt's get digi with it! Digitizing a Guitar
« Reply #20 on: November 05, 2007, 04:45:31 PM »
Oh yeah I forgot, what kind of angle is needed to get a decent point file? Is the photo you posted earlier like you think I should set the body up with, and if so, are the polar array lines about what you think is needed?

Now come the really not understanding part. If the photo represents your optimum cpl for this guitar body, why wouldn't a symetrical polar array based on the therotical center of the body be a better solution? The reason I ask, is if you choose the center/1.5" from left side cpl it looks to me like you are going to have some point not be picked up due to the leg length no being long enough on the right half of the guitar?

Questions......questions?

Mike

vmax549

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Re: Lt's get digi with it! Digitizing a Guitar
« Reply #21 on: November 05, 2007, 05:38:20 PM »
MIke you can reference you machine or not it does not matter in the end. As long as you do not rezero or re reference after you have started working.

I would reference the machine and then JOG over to where I wanted the CPL then take a tape measure and measure to the furtherest point of the object away from the tip of the probe. That will be the leg length I would add about a 1/2" more to be safe. The safe Z height is the height that you see on the Zdro that is safe for the probe to travel in without hitting anything. The probe height is the height that you want the probe to probe in so it can touch the object.

Now you can start the program file . there will be several boxes pop up to allowing you to enter the config info. it will be done one box at a time. when you input the values and press enter then the next box will pop up,etc

Just for a general test I would set the resolution  (leg separation angle) to 10deg that will give you a real course resolution but will go faster as there are less cycles to complete. To do a final resolution for real work take the diameter of the circle and solve for circumference. Next take the distance appart that you want each leg to be( probe tip diam works well for fine resolution.) and divide it into the circumference this gives you the number of legs you want to use. next divide 360 by the number of legs and that will give you the angle setting.

I guess I can make that part easier if the CONFIG asks you a few more question.(;-)

For the first test run I would set the probe to probe above the object to run in air and trip the probe with my figure. to make sure you do not break the tip(;-) It will cycle as follows. It will raise up to the safeZ height then travel over to the outer legnth of the first leg. It Will then lower down to the probe height and begin the cycling it will move towards the CPL postion until it either hits , or reaches the CPL. It will then move diagonally to the next start position and repeat the cycle. It will cycle all the way around the object . When it it complete it will closed down the saved points file.

If for some reason the probe sticks and MACH gives you an error ans stops. Wait until the cycle start button shows a black ring around it instead of yellow then press cycle start to resume. (Art is working on that part)

To calibrate the probe I will have to send you another code file that will find the center of a circle and report the diameter. You probe a known diameter hole. then you can set the tip dia comp on the SETTINGS page in mach.
then go back and redo the COC and check the diameter to see if it is correct. If not change the COMP value to make the diameter come out correct. That way when the probe trips during a cycle, mach will record the position of the edge of the  tip not the centerline of the spindle.

(;-) TP
« Last Edit: November 05, 2007, 06:01:11 PM by vmax549 »

vmax549

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Re: Lt's get digi with it! Digitizing a Guitar
« Reply #22 on: November 05, 2007, 05:54:28 PM »
AH but they are good questions(;-)

If you can imagine the array located at a point on the body. ( I have one printed out on a transparency that I can lay on top of the object or drawing) Then you can follow the lines down to the center point to see if the probe is going to be able to touch all the surfaces. You will see IF there are any voids where the probe will not touch. The overlay does not have to be finely graduated you can simply rotate it on the centerpoint to see all the possible approach legs.

Heck even a piece of string with one end held on the CPL and rotated will let you see the voids. The overlay just lets you see ALL the angles at one time so you can move the CPL around to pick the best spot.

(;-) TP
« Last Edit: November 05, 2007, 05:57:37 PM by vmax549 »

vmax549

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Re: Lt's get digi with it! Digitizing a Guitar
« Reply #23 on: November 05, 2007, 08:21:04 PM »
Here is a tidbit for those that always wanted to CNC port cylinder heads but did not know how to probe the ports for a reference.

If you start out with a probe tip the same shape as the cutter tool you will use (WE use a 3/8" ball tipped tool on a long taper shank) then you can take the polar array and probe a slice section of the port one step at a time.

For example position the head in a fixture you would use to hold it during machining. Pick a center point location that allows you to get as far down the port as possible. Next start the array running and allow it to step down a certain amount each cycle. When you have reached the bottom you will have series of slices that can be used to create a cutting program to replicate what you have probed.

Next rotate the head in the fixture to setup the other end of the port and repeat the process.

As long as you use the same shape tip as the cutter then the probe shape will translate directly to the cut shape accurately.  You can then cut it like you probed it.

Just A Thought (;-) TP
« Last Edit: November 05, 2007, 08:48:35 PM by vmax549 »

vmax549

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Re: Lt's get digi with it! Digitizing a Guitar
« Reply #24 on: November 05, 2007, 08:47:00 PM »
Mike if yoou find that you cannot get all the points then the array gives you the ability to move to that area and tune the array to the shape of the area you need to pick up.

For example say you could not get all the point in one of the curves in the neck area. After you have done the initia array look at the tool path window and you will see all of the probe points displayed for you to see. If you see some areas missing then move over to that area and setup another run this time with the interior array. you can setup just an arc to probe a certain area. you can start at any point and stop at any point. Being able to tune the array makes it very handy. Remember the ZERO deg stating point is at the 3oclock position on the array based on the x axis.

If you have a transparency overlay make sure you print the zero point on the array that way you can lay it on the part and see where you need to start and stop the array and setup the CPL.

Make sure you name the second file something different. I use the old add a number to the end of the file name trick. IE: guitar1,guitar2,etc.

When you have collected all the points you need just cut and paste the files together or append them all on to the master filename. Then when you import them into your cad they will all be there. You can then clean up any wild dots and smooth the curves.
« Last Edit: November 05, 2007, 08:50:36 PM by vmax549 »
Re: Lt's get digi with it! Digitizing a Guitar
« Reply #25 on: November 05, 2007, 08:53:23 PM »
Hi Terry,

I just got back from helping my son in law process some fresh venison. I'm tired and will now wait till morning to test the array code.

I kinda suspected you were into motors of some sort when I saw your post about cam grinder over on the yahoo group and now that I have seen the head porting post I know for sure you are. If I could show you the other project I am working on I bet it would get you going. Full size car body made from slices of foam 1.5" thick then glued together to make a plug. This thing is going to be nice.

Mike

vmax549

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Re: Lt's get digi with it! Digitizing a Guitar
« Reply #26 on: November 05, 2007, 08:56:10 PM »
Tip diameter note: The smaller the tip diameter the less distortion of the point position due to acute angulation from the approach angle verses the surface angle. That is to say if the surface angle has a steep angle to it the trip point may deviate slightly due to the surface touching the side of the tip instead of headon. Machs Tip comp is calculated from a headon approach angle.

(;-) TP

vmax549

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Re: Lt's get digi with it! Digitizing a Guitar
« Reply #27 on: November 05, 2007, 09:03:34 PM »
If you want to see what the shape file will look like as a line drawing

Then take a copy of the point shape file and add a G1 as the first line. Then load it up in mach as a GCODE file. You should see the shape file as a line drawing in the tool path display.

(;-) TP

Offline Chip

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Re: Lt's get digi with it! Digitizing a Guitar
« Reply #28 on: November 05, 2007, 10:42:45 PM »
Hi, Terry

Would you post an example "shape file" for us to look at and how to load/import into a Cad program.

Just getting started with probing hear.

Thanks, Chip

Offline Chip

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Re: Lt's get digi with it! Digitizing a Guitar
« Reply #29 on: November 06, 2007, 12:49:42 AM »
Hi Chip,

To make sure you are aware, this array system Terry has developed is currently for 2d point finding. With that said, nearly any 3d model that has an odd outside shape or cavity that needs to be reversed engineered can be probed for the data. Here I am speaking like someone who knows what I'm talking about, but I will actually get to run my first test tomorrow morning. Terry developed this to help me get a profile of a guitar that I just could not get in cad. I tried several times and it was taking way too much time. If you want I can post some sort of model tomorrow morning for a sample.

Mike

Hi, Mike

Thanks for the Reply

I had posted  this Nov 2006

Hi,Art, Brian and All

Is there a way Mach3 can follow a X,Y path, set to pick-up Z value (set to probe at X Y move distance  say .250) and incorporate it into a new file with X Y Z moves.

Need to trim off some excess edges, on some (one off) curved shapes 2 x 4 feet, plasma, Water-jet ?.

Any Thoughts Ideas ??

Thanks, Chip