Why oh why does this keep happening

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cabnet636
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Re: Why oh why does this keep happening

Post by cabnet636 »

then do a screen shot of the toolpath info,, i agree with tim

step back and take some pics of how you are holding the material down?
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IslaWW
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Re: Why oh why does this keep happening

Post by IslaWW »

My guess is that the problem is either lost steps or a loose grub screw on a pinion or pulley. In each case where the Z depth error occurs, there is a deep plunge.

If lost steps, setting slower speeds for the axes will solve the problem. You may be able to tweak velocity or similar settings in WinCNC to improve 3D cutting.

You should take a look at all the set screws on all pulleys, especially on the Z, burt if you find one, look over the X & Y also. Make sure motor to lead screw connections are tight also.
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Re: Why oh why does this keep happening

Post by Xxray »

* Would like to make a simple domed type 3d file to run, unfortunately I don't have any software that I can make 3d files with as of yet
* Machine is well lubed, all connections/hardware tight
* g09=s35
[Z Axis]
axisspec=p0 s2 d2 r2263.3776 o0 b0.000 a300 f200
axisvel=r400 f300 s20 m50 h200 c10
axishi=p3 b0 o1
altaxislo=p3 b1 o1
[axislo=p1 b4 o1
* Not sure about gear ratios, and offhand cannot see how a spring could be mounted to assist the Z
* James, I was going by memory, and saw something on the CAM site about 3 months of http machine support, I assumed there would be a charge after that period. If not, I stand corrected, will post back on cam forum. Hold down method is via 2 wood screws
* Was not, and am not, going to post the .crv

Thanks everyone, hoping to get this resolved !
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Re: Why oh why does this keep happening

Post by cabnet636 »

i have a file we use to test for this, call joey and get my number tommmorrow we can get you going
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Re: Why oh why does this keep happening

Post by cabnet636 »

take the g09 down to 15
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Re: Why oh why does this keep happening

Post by Ken Rychlik »

I agree with not posting the paid for file. What would help is to cut the tap file in half and post the first half anyway.

Seeing what kind of moves and what feeds it is asking of the z is what Jim is looking for.

I was going to say 20 on the S09, but I have servos on mine. 15 may be best for steppers.

Depending on the feed speed for the z in the file, you may be able to tweak the z acel i the ini file. that is the last figure in the top line of the z info. a is the acel of z for rapids and f is feed acel for the z.

I see that camaster is helping you out on their site, so that is a good thing. While I run a different brand, they seem like stand up folks over there.

It can be very frustrating getting something resolved at times, but if you give them a chance, I'm sure they will get your issue figured out. Let us know when it's over so we aren't all worried about you. :?:

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Re: Why oh why does this keep happening

Post by Xxray »

Cam are stand up guys indeed, along with the posters there.
Very knowledgeable folks, more than one of them have held my hand more than once getting me started.

I guess I should clarify ,,, Though I will try the recommended settings, I have successfully cut this very same design with the same control settings more than a dozen times in the past with no problems, some I have posted in the gallery section here.
For that reason, I'm doubting if tinkering with control settings will solve the problem, though the change may well be for the better, over all.
Doug

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Re: Why oh why does this keep happening

Post by toymaker »

Hi
Have you tried to run the same file twice so you know if the proplem occours at the same spot. That was the case with my first machine ( a victor 1200) and the solution was simple once we found it- reload the program that controls the CNC (I do not remember what program on that machine, in my machines now it woud be Xilog or syntec)

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Re: Why oh why does this keep happening

Post by Xxray »

Problem has happened more than once, with the exact same file, and with new ones.

Got brave and tried a cut on a chunk of walnut, I was feeling lucky.
Did 3 things different, not the best way to troubleshoot, I know.
I tried lowering the G that James suggested. I lowered the plunge & feed speeds, and I made the cut itself less deep.

Here is the result. The misstep in the arm of the cross, while less noticeable, is still there. Also another nasty misstep which runs down the center of the face, and all the way down the body. Only + over the previous is at least there are no flat spots on the high points.
Attachments
1 (Large).JPG
Doug

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Re: Why oh why does this keep happening

Post by Rick O. »

One simple way to begin checking for mechanical problems is to cut a series of concentric circles, fairly deep, with the same spacing between each. Many mechanical problems show up with this simple test, as the circles will oblong or unevenly spaced. The same thing can be done by cutting an evenly spaced grid or narrow lines, although uneven circles seem to catch the eye a little more easily. This is a basic first accuracy test to make with most any cnc equipment, from lasers to routers. We also used to do this test regularly on a 72-needle cnc embroidery machine, to check for mechanical wear or loose drive components.
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Re: Why oh why does this keep happening

Post by gilgilu2 »

I would suspect the power supply in not stable. Maybe the supply voltage comming into the shop is fluctuating. That will cause your stepper motors to act up. Just a thought. I run my controller off 2 car batterys for the 24 volt needed to run the stepper motors and the router motor runs off a 2000 watt inverter off the same battery bank but only on 1 of the batterys. I keep a 6 amp battery charger connected to the 12v side of the battery that runs the inverter and router motor. The land line power can quit altogether and my cnc setup keeps on running without any brown outs.
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Re: Why oh why does this keep happening

Post by signmarketingman »

When you start the job... cut it into some cheap foam. Avoid the expensive stuff until you get this resolved.
Measure the height of the bit from the table. USe a good measuring device that is accurate.
Run the job.
Measure the height again.
I am positive you will find a different reading. It may not be much more than a fraction of an inch.
If you do find a difference you will know it to be dropped steps.
Now you can fix whatever is causing those missed steps./
If do not find a difference then you will know it to be a hardware software problem.

Check your power settings to make sure there is no stand by mode activated after a motor is idle for a short period. Some drivers let a motor go into a stand by mode to keep them from heating up. If it is in stand by mode the motor may not come into active again and move the first few steps until it gets polarized again.


OR
you can change the direction of the cutter. Instead of going the long way change it to go the shorter way. See what happens.

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Re: Why oh why does this keep happening

Post by davewierenga »

Don't know if this helps, but I had the same problem using Mach3. I keept lowering the velocity and acceleration until the problem went away. Not very scientific, but it solved the problem.

Dave :?

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Re: Why oh why does this keep happening

Post by Xxray »

Thanks for the tips, will update when able.
Doug

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Re: Why oh why does this keep happening

Post by jmkissell »

I had a similar experience.
It was just missing steps now and then.
Unfortunately I also tried several things at the same time.
But I think the thing that made the difference was this:
My machine had a 5 start lead screw on the Z Axis.
I changed it to a 1 start screw and I have not had the problem since.

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