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Author Topic: Digitizing  (Read 77893 times)

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Re: Digitizing
« Reply #60 on: June 05, 2007, 09:56:17 AM »
That sounds like a good idea. I am taking a look at itpstyli.com. The first thing I notice is their styli have male threads. One of the things that makes my assembly economical is having male threads on the shaft coming out of the bottom of my probe. It is actually a 4mm x 0.7mm cap screw that runs through the hub (the part that holds the contacting pins). I am making the hub out of Delrin now (HDPE is just too gooshy) and it is easiest to make if I only have to drill out the center to fit the screw rather than tapping it. Then a nut is put on the end to hold the screw in the hub. If I tapped it, then I wouldn't have the cap head of the screw to hold the main spring from moving lateraly and I don't want to rely on tapped plastic because it is too easy to wreck the threads and they loosen faster with use. So I don't want to make the hub with female threads. So all I have to do is supply a threaded female coupler that will thread onto my probe's male thread and accept a 4mm male threaded stylus, which can be found at itpstyli.com.

Jeff Birt, thanks for your input. I have decided to include the threaded female coupler so people can buy a standard stylus. Also, if they wanted to use a stylus with a different size thread, they can make an adapter that has 4mm threads on one end (to fit the probe) and whatever size thread on the other end for their stylus. Or they can still just make their own stylus with femaile threads.

I still want to know how they attach ruby balls to styli -- can't find that yet!
« Last Edit: June 05, 2007, 09:59:23 AM by TetraLite »
Re: Digitizing
« Reply #61 on: June 05, 2007, 09:56:55 AM »
Great lead Jeff!
It would be a good idea to standardize the mounting to fit a common probe tip to give people a choice for the future.

DIY ought to work if the rod tip is cut out to roughly fit the surface of the ball and then a microscopic
drop of high strength epoxy is used to permanently attach it.
Re: Digitizing
« Reply #62 on: June 05, 2007, 10:01:00 AM »
Is that how they attach those balls commercially?

Waitg a sec... what am I thinking!... I can just use a female threaded coupler in place of the nut that holds the screw in the hub. Then a 4mm stylus can just mount directly. (I could save a part if the hub didn't have to be an insulator.)
« Last Edit: June 05, 2007, 10:04:25 AM by TetraLite »
Re: Digitizing
« Reply #63 on: June 05, 2007, 04:37:13 PM »
What format does mach 3 store the file as?
Artcam pro wants an ASCII G-Code toolpath format.
Is it compatible?
Re: Digitizing
« Reply #64 on: June 05, 2007, 04:52:03 PM »
Hi Mark,
If you want to make it as convenient as possible for people to buy styluses, you might want to
consider using 5mm thread instead of 4mm.  I checked their web site:
www.itpstyli.com  and there are 87 choices of 4mm tips but an incredible 379 choices of 5mm tips.
Hopefully it will help to make your probe sell more.
Re: Digitizing
« Reply #65 on: June 05, 2007, 06:51:46 PM »
Mach3 stores the output of a digitizing file in ASCII text format. Each line of text represents a sample point. Here is an example of a tiny part of a file from a scan using the digitizing wizard that is clumped in with the other wizards:


These five lines define five points with x, y and z values delimited with commas, so the first line says x=0, y=0 and z=-0.01859.

As the program samples points, it increments the x location by the x step value you specified, taking a z sample every step, until it reaches the maximum x dimension that you specify in the set up. Then it increments y by one step unit and then, starting at the maximum value of x, it decrements the x value back down to x=0 taking a z sample at every step. Then it increments y and so on.

You need to turn this "point cloud" output into G-code and I haven't even tried yet and I don't know what program would be the best for doing that. If you have a program that accepts comma delimited x,y,z point cloud files and can convert them to dxf files, I think that might be a good way to go. I'm sure there are people on this forum that have some experience with turning point clouds into G-code. I haven't got that far yet myself. I do know that the Global Mapper program will accept point cloud files and turn them into dxf or JPEG image files and these can be converted to G-code with the right program, perhaps even with LCAM.

This is new territory for me also! Sorry I don't know more about it.
Re: Digitizing
« Reply #66 on: June 05, 2007, 06:57:27 PM »

With my latest plan, it will be just as easy to make the probe accept 5mm styli as 4mm ones -- just a matter of hole and tap size on the threaded coupler. I will make that an option. ;D

Offline ger21

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Re: Digitizing
« Reply #67 on: June 06, 2007, 09:20:55 PM »

You need to turn this "point cloud" output into G-code and I haven't even tried yet and I don't know what program would be the best for doing that.

I wrote an AutoCAD macro to create 3D faces from the point cloud. http://www.artsoftcontrols.com/forum/index.php?topic=2421.0

You can use a CAM program like MeshCAM to create the g-code from the .dxf of 3D faces.

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Re: Digitizing
« Reply #68 on: June 06, 2007, 09:43:14 PM »
I will definitely check that out, Gerry. Thanks! I found a point cloud macro for ACAD online somewhere, but they wanted money for their version that wasn't crippled. I have MeshCAM so I can try out your method.

WYO_123, are you getting this?

Today I am testing repeatability of my digitizing probe design down to resolutions in the 1 hundred-thousandths range (0.00001") and getting some interesting and amazing results. I am scanning an area of the table of my Taig mill as a test surface. When I get it all sorted out and interpretted correctly I will post the results on http://tetralite.com/probe

Update: I have posted some test results on that page. The probe seems to have measurement repeatability better than 0.0002" and actually somewhere around 0.0001". I also discovered the the table of my mill slopes down from front to back at the rate of roughly 0.0001" per inch (a real rough estimate).

Probes will be available for sale soon at www.tetralite.com/probe.
« Last Edit: November 07, 2007, 02:12:15 AM by TetraLite »

Offline GaryB

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Re: Digitizing
« Reply #69 on: June 07, 2007, 08:59:49 AM »
Gerry, you wrote your macro as an Autocad plug in, can your converter work outside the box such as a small exe file whereby you can run the digitized point cloud file through it and have it converted to 3d faces (3ds) type format? this would be a quick loading into most modeling software for clean up and toolpathing. 
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