Messages

1

General Mach Discussion / Manual Tool Change

« on: February 17, 2012, 10:00:34 PM »

I am using cut 2-D and have a router CNC operating with homing limit switches on one end and using max limits on the 4th input as well as soft limits, I have just been doing basic cut outs with flat head end mills thus far. I would like to start adding detailed cuts to my parts such as bevels but am unsure of how to handle the tool change. Because of the limit switches I know I cannot use auto-zero.

 How can I do this manually if my tools are different length? Do I adjust when the machine pauses and requests a tool change by moving the machine off of the part, change the tool, bring it back over the part and touch off to the surface and re-zero the Z only?

I have looked for steps and detailed guides on how to do this but I am unsure and really do not want to damage anything.

-Silent

2

General Mach Discussion / Re: Help Needed: X-Axis skipping

« on: February 12, 2012, 02:18:39 PM »

here are a few pics. i don't know specifically what you want.
http://www.flickr.com/photos/67884472@N07/6864402925/in/photostream/
http://www.flickr.com/photos/67884472@N07/6864401911/in/photostream/
http://www.flickr.com/photos/67884472@N07/6864401359/in/photostream/
http://www.flickr.com/photos/67884472@N07/6864399755/in/photostream/
http://www.flickr.com/photos/67884472@N07/6864396811/in/photostream/

3

General Mach Discussion / Re: Help Needed: X-Axis skipping

« on: February 12, 2012, 11:55:09 AM »

I did the outer circle with a 1" diameter. The dimensions I measured for the diameter are 1.011", 1.006" & 1.014". I was cutting at 12in/min with a 0.050" depth of cut and a 1/4" 2 flute end mill on fiber board. What can I do at this point to get more accuracy?

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General Mach Discussion / Re: Help Needed: X-Axis skipping

« on: February 11, 2012, 11:32:11 PM »

So I did as you recommended. I measured +X to be 1.002 and -X to be 1.000, I did it a second time and got +X to be 1.002 and -x to be 1.001. In the y direction I got +Y to be 1.002 and -Y to be 0.996, and a second time I got +Y to be 0.995 and -Y to be 1.000. After that I tried to mill another rectangular pocket using the wizard. It was suppose to be a 1" X 1" square pocket, its actual dimensions are 0.975" X 0.984".

Would that be backlash?

What steps should I take from here?

5

General Mach Discussion / Re: Help Needed: X-Axis skipping

« on: February 11, 2012, 06:40:08 PM »

Hood,
I did as you recommended the results are as follows
using a digital caliper that was fixed. moving +/- 1 inch in mdi
x axis
test 1
move to 1: 0 -> 1.0005
moved back 0: 0 -> -1.0055
test 2
move to 1: 0 -> 1.0055
moved back 0: 0 -> -.9925

y axis:
test 1
move to 1: 0 -> .9975
moved back 0: 0 -> -1.001
test 2
move to 1: 0 -> .999
moved back 0: 0 -> -1.000

i understand that just because a caliper goes to 4 decimals doesnt mean its accurate but I am wondering if my 5 start lead screws are to blame, or the fact that my velocity is 200 and acc is 12  could  i be over coming some friction that is making my machine be off? also this  test was conducted  when the machine has no load ( not milling)  so i would imagine that it would be even worse like i saw with my 1 " cut out of a circle.
when thinking about cutting out a detailed objects a couple of thou. here and there could really add up. Any suggestions?

6

General Mach Discussion / Re: Help Needed: X-Axis skipping

« on: February 11, 2012, 04:55:24 PM »

Hood,
Thank you for your help. I changed the values to 25000KHz and the pulse settings to 10 and 10  in both x  boxes and y boxes.  After changing these settings I decided to try cutting a 1" dia hole in hardboard ,  feed rate was 20, d.o.c was .050 with 20% step over I was using a sharp .25" endmill 8000 rpm. The hole came out to be .987 in the x  and .978 in the y.  When I cut my first circle on the machine when I got it running I thought I was a lot closer to 1 in both x and y, could changing pulses have affected this . Or do I have some kind of backlash, machine is brand new  fresh acme nuts and all. Or am I being too picky and is this what the community would call reasonable for a 1" dia hole

7

General Mach Discussion / Re: Help Needed: X-Axis skipping

« on: February 11, 2012, 11:29:04 AM »

Hood,
my velocity is 200 and acc is 8 is this very high? my only comparison is from my 3d printing experience where this is rather low. My step pulse is 2 and my dir pulse is 2 also  is the step pulse what you  mean by pulse width? My kernel was set to 25KHz but in a effort to figure the problem out myself i choose to bump it to 45 to see if it made a difference, I have since moved it back down to 25.
 If dells are known to have dirty pulses  could you recommend any aftermarket cards that work well with cnc's I have been looking on newegg and found a few but in the reviews i have seen some people where intending to use the cards for cncs and could not get them to perform.
 Lastly in regards to my x and y leadscrews i am using 1/2 by 10  lead screws  with 5 start  i have had alot of luck with these in a prototype 3d printer i am developing.

8

General Mach Discussion / Help Needed: X-Axis skipping

« on: February 10, 2012, 11:36:54 PM »

I got Mach three from my mother-in-law and upon running a couple programs I am getting skipping in the x-axis, I think.

I have attached my xml file and in it you can see the last thing ran was a rectangular pocket that I selected through the wizards tab.
I am using a Gecko G540 which powers 3 380oz-in stepper motors powered by a 48volt power supply. I am running the software on a Dell with 2Gb ram and a Pentium D Core-2 Duo running windows 7 32bit. On the CNC I am using a 3.5hp Bosch router with a ¼” end mill and all I am doing is climb milling.

I have attached a picture of the last program ran where it skipped steps and plunged into the side. I also attached a picture of a circular vent I tried cutting a few days ago when the error first occurred. I am cutting fiber board as seen in the picture.

I am very experienced with 3-D printing and the small stepper motors used with that set-up. I figured the 380 oz-in stepper motors should have plenty of torque to take 0.020” depth of cut at 15 in/min at 800 rpm with ¼” end mill climb milling in fiber board.

Please, if you could be so kind, recommend options to help correct this problem. Thank you for your help.

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General Mach Discussion / Re: Mach3 and VCarve

« on: February 05, 2012, 02:31:01 PM »

Resolved don't buy from ebay

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General Mach Discussion / Re: Mach3 and VCarve

« on: February 05, 2012, 02:12:21 PM »

Hood, I believe this is what you were requesting. its the only one i know of. i was told to put this in the mach 3 folder from the gecko g540 tutorial.