can someone tell me what im doing wrong???

tsikows
Posts: 38
Joined: Fri Sep 12, 2014 11:25 pm

can someone tell me what im doing wrong???

Post by tsikows » Sun Oct 12, 2014 2:45 am

About ready to just sell this damn thing. finally figured out my problem and i still cant make a part without a crash. i have been trying to make my new makita mounts without any success. now tonight i finally worked out my z axis problem and i get my first mount 90% done and the spindle decides to crash right through mount. this is getting so frustrating and i have no idea why i cant get this damn thing to work.

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Xaracen
Posts: 124
Joined: Sat Apr 20, 2013 7:41 am

Re: can someone tell me what im doing wrong???

Post by Xaracen » Sun Oct 12, 2014 8:21 am

Well, on almost every occasion this has happened to me, either the bit wasn't tightly enough set in the collet, so its height changed, or it was cutting too deeply that the x- or y-steppers lost steps so the positioning was lost, and often both issues occurred, the second caused by the first.
Making sure the bit was well tightened in the collet made a dramatic fall in the number of these unfortunate occasions, and not cutting too aggressively pretty much eliminated the rest. Very rarely, the piece itself moved during milling, because I hadn't held it firmly enough with whatever method I was using.
Shapeoko v1 #????
500mm Y-slides with dual Y-steppers
375mm dual X-axis gantry
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Arduino Uno running grbl v0.9i with grblShield v4.

Ing Chao
Posts: 72
Joined: Fri Dec 28, 2012 7:10 pm

Re: can someone tell me what im doing wrong???

Post by Ing Chao » Sun Oct 12, 2014 2:21 pm

What electronics are you using? Do you have a fan over the drivers? I have a Grbl shield and before I put a computer fan over it, I had this problem on EVERYTHING I tried to cut.
Between making sure the collet is tight as Xarecen mentioned, and keeping the drivers cool-you should be able to virtually eliminate the problem.
'Oko #1153- D Extended Y axis-1000mm. Dual X axis makerslide-900mm Nema 23 X and Y axis motors. Arduino Uno and Grbl shield controller running on 24v.

tsikows
Posts: 38
Joined: Fri Sep 12, 2014 11:25 pm

Re: can someone tell me what im doing wrong???

Post by tsikows » Sun Oct 12, 2014 3:19 pm

I'm sure it is not the bit coming loose in the collet, as I have checked it after every cut and it has been tight every time. Even tightened with the two spanner wrenches rather than the lock button. I'm cutting HDPE that is .62" thick at a feed of 800mm/s, dpp 1mm, step over of 2mm. As far as I am aware that is super conservative for cutting hdpe. I'm also using my rt0701c with a 1/4 4 flute endmill.

tsikows
Posts: 38
Joined: Fri Sep 12, 2014 11:25 pm

Re: can someone tell me what im doing wrong???

Post by tsikows » Mon Oct 13, 2014 5:31 am

this is absolutely ridiculous. I ran it again today after going through every possible issue that could cause missed steps. i added a fan to my adruino and gshield blowing across the both of them. nothing got hot what so ever during the operation. y motors were cold to the touch, x and z motors were both warm but by no means hot when it happened. i read through this entire post http://www.shapeoko.com/forum/viewtopic.php?f=10&t=512 and fixed or adjusted anything mentioned. i went through and tightened all belts, tightened all nuts and bolts, made sure all my set screws were tight, adjusted all of the v-wheels to be perfect, everything is aligned and squared perfectly. went into grbl settings and put all of the default seek, feed, acceleration, everything! i set everything exactly to what the assembly instructions say it should be. and once again i get 90% done with the cut and it dives in and ruins the entire part. can someone run the code for me on their machine and tell my what the heck is going on here? i have tried over and over to create new tool paths and i have run them through open scam without a hitch. i have no idea what is going on here. my tool paths are done in meshcam.

here is the code that i used most recently:
rt0701cmountupdatepath6.nc
(472.25 KiB) Downloaded 51 times

chris33
Posts: 51
Joined: Sat May 25, 2013 6:36 pm

Re: can someone tell me what im doing wrong???

Post by chris33 » Mon Oct 13, 2014 6:30 am

skipping steps is not just heat issue you may not be supplying the motors enough power or maybe too much? get the multimeter out
Prusa i3 3d printer
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AlBorland
Posts: 75
Joined: Mon Jun 23, 2014 5:26 pm
Location: Austria

Re: can someone tell me what im doing wrong???

Post by AlBorland » Mon Oct 13, 2014 9:12 am

I tried to run your gcode on my tinyg. It took 44 minutes to run that 27000 gcode lines (yikes!). And it started acting up around line 23000: could not hold a constant velocity and came even to short stops because the gcode sender could not keep up and the queue was starved. I don't know if this is the cause of your problem, but it may well have triggered it.

You should
1. look for a postprocessor that supports G2/G3, the current file uses very small straight line segments (down to 0.1mm) to approximate arcs. That alone should cut the file size down to below 1000 lines. Maybe the other people who use MeshCam can help here.
2. clean up your design and/or toolpaths. Get rid of the pocket operation and replace it with an inside profile for the big center hole. Look at the lower outside edge (seems to be not really parallel to the x axis, and there's another toolpath doing an extra cut on the right half of the lower outer edge). Use a single cut instead of the double-wide slots, the cuts are clean anyway. Finish each of the inside profiles, then do the outside profile, to get rid of the numerous traverses.

When I look at the picture you posted, I see that it messed up just as it reached the spoilboard. Was it that way every time? I also see that it melted the plastic when plunging down, but the other cuts are clean and produce nice chips. Does the bit have a center cut? Why 4-flute?
Shapeoko2, 4xNEMA23, tinyg, Kress 1050, various Z axis modifications

tsikows
Posts: 38
Joined: Fri Sep 12, 2014 11:25 pm

Re: can someone tell me what im doing wrong???

Post by tsikows » Mon Oct 13, 2014 1:54 pm

AlBorland wrote:I tried to run your gcode on my tinyg. It took 44 minutes to run that 27000 gcode lines (yikes!).
this is something i had been wondering about since i first ran my own design. the run times and number of lines just seemed excessive on everything i made so i began to think it was normal.
And it started acting up around line 23000: could not hold a constant velocity and came even to short stops because the gcode sender could not keep up and the queue was starved. I don't know if this is the cause of your problem, but it may well have triggered it.
that is just about the same spot it fudges for me every time as well. it gets down to a few thousand lines of code and chokes.
You should
1. look for a postprocessor that supports G2/G3, the current file uses very small straight line segments (down to 0.1mm) to approximate arcs. That alone should cut the file size down to below 1000 lines. Maybe the other people who use MeshCam can help here.
what is the postprocessor? i have heard it mentioned on several occasions but have no idea what it is or does, nor does there seem to be any info on them in the wiki or anything.
2. clean up your design and/or toolpaths. Get rid of the pocket operation and replace it with an inside profile for the big center hole.
This is one thing i didnt like either. i didnt want to cut that entire big circle, rather cut it like the small one, leaving the center alone. but because of the way meshcam operates it wanted to cut it like that every time. Meshcam does not have machine operation options such as profile, pocket, slot, things like that, it basically does a profile operation every time. this is one thing that has prevented me from purchasing it thus far.
Look at the lower outside edge (seems to be not really parallel to the x axis, and there's another toolpath doing an extra cut on the right half of the lower outer edge). Use a single cut instead of the double-wide slots, the cuts are clean anyway. Finish each of the inside profiles, then do the outside profile, to get rid of the numerous traverses.


not sure what you mean by not parallel, mine appeared parallel on my machine. the random extra tool path is another unknown. just something meshcam threw in there. also no way that i am aware of the modify tool paths in meshcam. the double wide slot it just the way it designed the toolpath. maybe rob from grz could answer some of those questions for me but for now im more concerned about the root cause.
When I look at the picture you posted, I see that it messed up just as it reached the spoilboard. Was it that way every time? I also see that it melted the plastic when plunging down, but the other cuts are clean and produce nice chips. Does the bit have a center cut? Why 4-flute?
yes it happens right at the bottom of the piece just about every single time. yes for some reason it melts the plunge cuts, maybe my spindle speed is too high for plastic? (makita rt0701c on lowest setting) yes it is a center cutting bit. the 4 flute was the only thing i could get my hands on. i wanted to try and buy locally but the options are limited so i opted for the 1/4 4 flute. an order has already been placed for a variety of bits to allow more options. thanks for the detailed reply.

AlBorland
Posts: 75
Joined: Mon Jun 23, 2014 5:26 pm
Location: Austria

Re: can someone tell me what im doing wrong???

Post by AlBorland » Mon Oct 13, 2014 4:13 pm

Most commercial CAM packages support different postprocessors for different machine types. I thought that Meshcam did too, but it seems it doesn't, and is also unable to put arc statements in the gcode file.

If you send/post a link to yout CAD file, I can take a look on other options.
Shapeoko2, 4xNEMA23, tinyg, Kress 1050, various Z axis modifications

tsikows
Posts: 38
Joined: Fri Sep 12, 2014 11:25 pm

Re: can someone tell me what im doing wrong???

Post by tsikows » Mon Oct 13, 2014 4:42 pm

i was going to post the cad file in my last post as well but could not get the forum to accept any of my files. can you only post svg files?

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