Messages

21

LazyCam (Beta) / Re: Download lazycam...having problem with importing a DXF

« on: June 01, 2007, 12:33:31 PM »

This may not be any help in this case, but for me, all my problems loading dxf files in LCAM went away when I made sure the same file wasn't open in my CAD program. Just thought I'd mention that because it is one thing that can stop a file from loading.

22

LazyCam (Beta) / Re: OK, I give up! How do I get ACAD dxf files to open in LCAM 2.02?

« on: May 31, 2007, 03:34:31 PM »

I'm using vers. 2005. It is definitely ACAD that is stopping me from opening files in LCAM while they are still open in ACAD. I know that because if I don't close them in ACAD they don't open in LCAM and if I close them in ACAD they do open in LCAM and it doesn't matter what version the files are in from R10 to 2004 -- they all work in LCAM as long as I close them first in ACAD.

When you do a conversion you probably are saving the file with a new name, so you are not trying to alter the original. Perhaps your conversion program doesn't look like a threat to the open file in ACAD because it is opening it as read only (I'm just guessing here), while opening in LCAM may be trying to open it with read-write capabilities enabled (still guessing).

All I know for sure is that with ACAD 2005 I can't open files in LCAM while they are still open in ACAD and the problem goes away when I close in ACAD.

23

General Mach Discussion / Re: Digitizing

« on: May 30, 2007, 04:30:55 PM »

I can answer all three of your questions with confidence: (1) I don't know, (2) I don't know and (3) I don't know!

I haven't really done much in the way of testing yet. So far I have just tried to see how well it can scan very small items using a needle point for a stylus. Well, I have done the hole center thing I described above and those tests show repeatability easily within a thousandth of an inch. I get repeatability errors of about 3 ten thousandths maximum (I haven't done a lot of tests). All this is, of course, dependent to some degree on the resolution and accuracy of the milling machine itself, determined by leadscrew slop and stepper motor resolution and whatever else there is to take into account. But it looks to me that if you're not shooting for accuracy better than a couple thousandths or so, this probe should be close enough.

Modified entry: I have noticed that in my scans of quarters and dimes that every other line is shifted a tiny amount along the x axis. This must be, I presume, due to end play of the x-axis leadscrew (what else could it be?). I am glad my machine is that tight! Perhaps it should be noted that my stepper motor settings for "Steps per" (which is steps per inch) are at 32000 which means in order to move a stepper motor one step on my machine I would enter G1 X0.00003125 and the motor moves one step, assuming X is starting from zero. Whether on not the table moves depends on end play and which way it moved the last time it was moved, I suppose. So I am set up for pretty fine resolution.

I haven't seen any options for CMM function either.

I have been wondering about the best way to get from point cloud to 3D CAD models myself. I will be experimenting with that soon I think. Seems like I saw something about that in this forum somewhere.

24

LazyCam (Beta) / Re: OK, I give up! How do I get ACAD dxf files to open in LCAM 2.02?

« on: May 30, 2007, 06:52:09 AM »

Haven't noticed the extra lines -- at least not yet -- but I will know what to do if it happens. Thanks again Fiedd!
So far the drawings I've been experimenting with are pretty simple - just a few circles and points for drilling.
Once I got the tool setup and how to manage the layers figured out, LCAM works pretty well. I have been using it to generate some usable G-code.

25

General Mach Discussion / Re: Digitizing

« on: May 30, 2007, 02:52:02 AM »

Some new pix of my probe (shaded in ACAD with the housing not shown so you can see inside):

In the above image you can see the springs that push the PC board down against the bottom cap. The setscrews used for adjusting the plane of the PC board thread through the bottom cap and push up against the bottom side of the board. Also note that I have added the jack for plugging in a 1/8" phone plug.

In this picture you can see the holes through the bottom cap for the setscrews and the long (2-56x1.25") screws that hold the probe together.
The setscrews are 6-32x1/4". The probe is shown here without a stylus which screws onto the 4mm x 0.7mm x 30mm bolt that runs through the hub (the part that holds the contact pins). I used the metric screw here because it was a better length than the cloest standard length #8-32 screw, so my stylus must have 4mm x 0.7mm female threads.


And here is a scan of FDR's ear on the front of a dime. Notice the big peak on his ear lobe. This must have been due to a false activation of the probe, perhaps caused by a vibration on my mill's bench. The image was generated in Global Mapper and it extrapolates the elevations between sample points. That is why the sides of the peak on the ear lobe are tapered to meet the surrounding sample points.  I haven't seen it do this before and I think it is because my latest assembly of the probe didn't put as much compression on the spring that pushes the pins against the balls making it too easily opened by vibration. The vertical exaggeration in this image is 10 times nomrmal. The scan was 0.12" by 0.12" with x and y steps of 0.002" making a total of 3600 sample points.

Below for download is my latest ACAD drawing in .dwg format. It is a three-dimensional drawing -- the same that I used to create the images above. If I save it as a .dxf file it is over 23MB. As a dwg it is 868KB. If you can open this 3D file in your CAD program you can measure everything or look at object properties to get dimensions which I have not put on the drawing. There are separate layers for everything.

26

General Mach Discussion / Re: Digitizing

« on: May 30, 2007, 01:31:02 AM »

Many responses here since my last one!

My probe definitely is not going to try to compete with the high-end ones, but I think it has enough accuracy for the everyday home mill. One test I am doing is running the "Center of Hole" routine that is built in to the latest Mach3 release. I just run the routine, reset x and y using the "Ref All Home" button and then run the routine again to check repeatability. After about the third time, I get errors no larger than .0002, and more often it is .0001 or even .0000 on the Mach DRO's. The first one or two repeats of the test usually shows a greater error than subsequent tests, so that indicates that the first test or two tend to have a greater error, becasuse the error is reduced every time by running the test three times. After three times I never see a difference of more than .0002. Yes, that's 10-thousandths. But not microns!

For those asking about Global Mapper, you can download a trial version that has crippled saves and exports, but it is good for evaluating the program. It is all mapping related, but it can manipulate elevation models in many ways and in reality we are talking about a kind of mapping anyway. When I open a point cloud file it asks which type of geographic projection you want to use. These are standard projection types that are used on maps and they usually take into account things like the curvature of the Earth (which is not enough to worry about in small areas) and how to display a curved surface on a flat one. You can even specify projections for some of the other planets! Depending on the projection system you pick, the point cloud file is opened using (usually) meters as the basic unit of measurement. If your original point cloud is in inches or millimeters it really doesn't matter because we are dealing with units and not inches or meters or whatever.

In the registered version, you can export to a huge variety of file formats for many programs including dxf points or converted to faces.

The trial version can be downloaded at http://www.globalmapper.com/ (click on "Download Trial" from that page). It can also be downloaded from the USGS at http://mcmcweb.er.usgs.gov/drc/dlgv32pro/. This version (they call it "DLVG32Pro" may be less crippled than the "trial" version -- I am not sure about that because I have the full version already and haven't bothered with the crippled versions. The large njumber of file formats that can be read by Global Mapper are listed at http://www.globalmapper.com/product/formats.htm. The point cloud files generated by Mach's wizard is a simple text file that is recognized by the Global Mapper program as an ASCII elevation grid file.

I haven't tried to use Global Mapper for generating a file to convert to G-code yet and haven't given it too much thought. I have so far used it for viewing point clouds with various shading techniques. On road trips I have a laptop computer with a GPS unit in the car with all kinds of mapping software including Global Mapper. I have digital elevation model files (DEMS) for the entire state of Washington (where I usually confine my road trip to). I also have geo-referenced topographic map files and other map format files and aerial photography for the entire state. These can be overlayed in Global Mapper to produce 3D images of the terrain (what it looked like a few years ago when the photos were taken. I can generate a picture of what it is going to look like around the next bend before I go there. Kinda fun. Anyway, Global Mapper is quite a program and could be useful for converting some formats into something useful for machining purposes, especially when dealing with images that you might want to engrave. I really haven't explored this possibility at all.

27

LazyCam (Beta) / Re: OK, I give up! How do I get ACAD dxf files to open in LCAM 2.02?

« on: May 29, 2007, 11:24:45 PM »

Hi Fiedd,

Well I'll be! I just opened a dxf in ACAD, made sure I saved it as a version R12 and then tried opening it in LCAM and it failed to open. Then I closed the file in ACAD (leaving ACAD still running) and tried opening it again in LCAM and it opened!!!

Thanks for that bit of wisdom, Fiedd. 

Apparently, ACAD is blocking access to that file from other programs while it is opened in ACAD, like some other programs do while their files are open.

And that explains why, when I use another program to make a copy of the file in a different version, that it works, because I am actually opening the new file I created while the original is still open in ACAD, so I'm not trying to access that one. It also explains a couple other strange failures that seemed to make no sense -- I don't remember the exact details now, but I know this was the reason.

Just tried it with a version 2004 ACAD dxf and it opens just fine as long as I close it in ACAD first!

Thanks again, Fiedd! You hit the nail right on the head!

28

General Mach Discussion / Re: Digitizing

« on: May 29, 2007, 03:15:00 AM »

Brett, Thanks for the fishing lesson. Yes, seriously, I will try to make it worth my while.

Hood, Yeah, I kinda like it. I need to finish my plan drawings, which means I have to finish making my latest revisions on the prototype, which means I will probably end up changing the drawings again. But I think I'm really close to finalizing it. Trying to make it as simple as I can so it can be made easily.

29

General Mach Discussion / Re: Digitizing

« on: May 29, 2007, 02:37:31 AM »

Ha ha! I've been called worse names than Mike! (with apologies to everyone named Mike)

Please explain how one goes fishing for free anymore! Again: Ha ha!

I keep forgetting to make money. But I am hoping I can offer these things at a low price. I think it is possible using the materials I'm using. Lots of plastic. Plastic is really fast and easy to machine. This will be a poor man's probe in that regard, but I think it is plenty good enough, at least for the hobbyist. I seem to get really good repeatability on measurements. I will have to do a lot more tests so I can come up with some good figures on how accurate it is.

30

General Mach Discussion / Re: Digitizing

« on: May 29, 2007, 01:57:22 AM »

Brett,

Well, I haven't committed to a price of $150 yet. That is just a guess. I *do* need to research my costs (time it takes me to make one mainly -- the materials don't cost much).

Forgot to mention that the tip I used for scanning the 1/4" square of the dime was made from an ordinary straight pin. In practical applications you would probably want a larger tip!

Which brings to mind a question that occurred to me last night -- How do they mount those ruby balls on the tips of probes?

Jeez! I sure like my adjustable PC board idea. Takes all the worry about precision out of the manufacturing as far as tip alignment is concerned.

(Correction: the name is Mark )