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Possible lazycam issue
« on: September 17, 2010, 06:44:42 PM »
Mach3 standard Milling setup


Ok I am new at doing machining using a CNC machine but I am learning quickly however this one has me baffled. When I first started I was using a program called kcam to do some quick test items to validate settings and the like . these items were two gears one about 4.5 inches across and about 106 teeth another about 2 with I think 41 teeth. I used a plugin for autocad to create the gears and then moved the dxf to kcam and cut the pieces which ended up being a bit rough. I was using a 1.5mm endcut bit and as I said it was a bit rough BUT the aspect which was fairly accurate was the tooth layouts. I am using 1/8 inch cast acrylic sheets and each I cut the pieces in three passes each 1/3 of the 1/8 inch so after the third cut i had my gears. The tooth cuts were exactly what I was expecting in the the tip of each tooth was pointing directly out from the center of the gear. I used the same gear program for each gears I just changed the number of teeth and the diameter changed according so the two gears should work together just fine and they do.

Now the weird part I since then migrated over to mach3 because the amount of flexibility I have here is vastly better than the kcam software but, my gears are not working and I need help in determining why. My process is this now. I import the dxf into lazycam clean it up and generate the Gcode and it loads it into Mach3  and then i proceed to cut the gear but the teeth all seem directionality to them meaning they do NOT point directly away from the center of gear they are all leaning forward. and I can't get them to be straight. I slowed down the feed, and adjusted the velocity and the acceleration both up and down and can not see any real affect..

The one thing I can think of that I have not tried yet and that is inside of lazycam there is the clean up function that I used and it may have adjusted the cut to make things faster and in doing so may have removed a key part of the cut by mistake.

Is this possible, please let me know.  If you do know what my issue is and it is not the cleaning aspect of lazycam,  please let me know that as well or any other ideas you may have.

So far I like Mach3 a lot better than kcam
Thanks
Jeff

Offline RICH

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Re: Possible lazycam issue
« Reply #1 on: September 17, 2010, 08:02:27 PM »
Jeff,
Don't think you will get a better definition than the one i defined in the manual, namely, Autoclean and Clean are both the same and just removes any extraneous data on import of a file.  So I am thinking it should not should not affect the gear profile that will be used to generate the code.

How about posting the following:
- DXF file of the gear as drawn in CAD
- The generated Gcode, but "only" for the gear profile from kcam or whatever program was used
-               "                                            "              from LazyCam

Then we can compare all three and see if it's a difference in produced gcode of one program to another against the original drawn profile.

RICH

Re: Possible lazycam issue
« Reply #2 on: September 17, 2010, 09:51:51 PM »
Thanks for the feedback Rick...I have two issues with that, one is me I am still so new to this and am jumping between version and software I think I may have either overwritten or lost my original kcam gcode file. The second issue is I was using an older version ofMach3 when I originally brought the ACAD dxf file over toMach3 and in that version it had a function to import the .dxf files directly. which is what I did the other option was to import the .jpg or .bmp files WITHOUT THE USE of lazycam at least that I could see. That version brought my .dxf file in just fine bit when I try to bring in the same file in from autocad into the latest version which is using lazycam the import does not locate any entities. So I have to figure out how to get the dxf to import the file again. The gear layout as defined in the ACAD object is a 'LWPOLYLINE' which the old version imported but at least right now I can't get lazycam to bring in. so all I have is the original file that the older Mach3 imported So I am uploading that file. After cutting these gears at first they start out normal and then in some sections the supposedly nicely round gear teeth look something more like a sharks fin with a stretched left edge as the cutter moves away from center then a sharper return toward center on the right side.

I was trying to find some kind of gcode simviewer but was not able to find one.

I will keep looking for the other files.

Thanks for your help
Jeff
Re: Possible lazycam issue
« Reply #3 on: September 18, 2010, 03:57:12 AM »
I think I got it resolved at least one part I still need to figure out the importing of dxf's into the latest version. I think, however, I have resolved my gears issue, the play I found seemed only to be in the x dimension it seem to be slipping now and then. So I moved the the cutter in the x dimension back and forth  but everything seemed smooth so I stopped and the cutter was at the outside limit and reached for something and brushed the cutter slight and I noticed that it movedjust a bit. Well I looked ea little more closely and saw that the block that was fastened to the threaded rod had come loose and I had about 3/16 of inch of play so while under a constant drive in either the positive or the negative seemed to work just fine the qucik little back and forth movement of cutting gear teeth was affected greatly  and randomly just depending on how much force was actually be put on the cutter at any one moment. That is why it appeared randomly around the outside edge of the gear.
Can't test cut a new gear until tomorrow cuz I live in an apt  but am looking forward to it now

if I could get my DXF's in I would doing great

Offline RICH

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Re: Possible lazycam issue
« Reply #4 on: September 18, 2010, 07:03:38 AM »
Happy you found the problem.
BTW....Some programs will automaticaly give you the Gcode for the gear but they break the curvature of the gear teeth into a number of
straight moves and that creates a lot of code. If you draw the gear out in cad you can  get arcs instead of straight lines thus reducing the the code
significantly and a true gear profile. Depends on how anal you want to be about the gear. I may also add that Art is creating a program for gears named Gearocia or someting like that. Anyway, i draw my gears based on standards and use a spread sheet to calc all the dimensions. Don't cut manny gears though.

RICH