plywood - detail lost

[Ployd]

We were cutting plywood and have lost some detail in the finished product. Some of the cuts aren't nice and straight compared to the drawing. I understand the notches not being round due to the cutter size (first image). But the rounded corner shouldn't happen (first image).

 

I'm not sure if it because some of the entitys are arc, splines, lines, etc.

 

Or if it is in our post. Sometimes we have I and J and sometimes we don't. From reading other posts it seems I and J are a good thing. From looking at the code it looks like the places where we had problems did not have the I and J. I included a sample of the code cutting the small square section with the radiused corners (second image).

 

We got the same results if we were running a high feed rate or if we slowed down the feed.

 

Thanks for your help and suggestions!!

 

File on ftp t.mcx

 

 

 

 

% TEST , MX ,

; PROGRAM - T

; DATE - 28-11-08 TIME - 17:40

N100 G70

N102 G0 G17 G40 G80 G90

N104 G53

N106 M73

; CONTOUR

; T2 .375 X 6.961 C FEM TOOL - 2 PIVOT LEN. - 16.73

N108 T2

N110 M6

N112 S9000

N114 M3

N116 G54

N118 G0 G90 B0. C0.

N120 X5.0743 Y47.7355

N122 G43

N124 Z1.25

N126 G51 A75 E0.030

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N136 X4.3489 Y48.4951

N138 X4.3382 Y48.5207

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N142 X4.3286 Y48.5747

N144 X4.3299 Y48.602

N146 X4.335 Y48.6286

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N150 X4.3563 Y48.678

N152 X4.3729 Y48.7011

N154 X4.3885 Y48.7179

N156 X5.0973 Y49.4062

N158 X5.1243 Y49.4288

N160 X5.1481 Y49.4433

N162 X5.1737 Y49.454

N164 X5.2004 Y49.4608

N166 X5.2277 Y49.4636

N168 X5.255 Y49.4623

N170 X5.2816 Y49.4572

N172 X5.3071 Y49.4483

N174 X5.331 Y49.4359

N176 X5.354 Y49.4193

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N194 X6.1102 Y48.5106

N196 X6.1013 Y48.4851

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N210 X5.2715 Y47.6852

N212 X5.2448 Y47.6784

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N216 X5.1902 Y47.6769

N218 X5.1636 Y47.682

N220 X5.1381 Y47.6909

N222 X5.1142 Y47.7033

N224 X5.0912 Y47.7199

N226 X5.0743 Y47.7355

N228 Z0. F40.

N230 X4.386 Y48.4443 F300.

N232 X4.3634 Y48.4713

N234 X4.3489 Y48.4951

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N238 X4.3314 Y48.5475

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N242 X4.3299 Y48.602

N244 X4.335 Y48.6286

N246 X4.3439 Y48.6541

N248 X4.3563 Y48.678

N250 X4.3729 Y48.7011

N252 X4.3885 Y48.7179

N254 X5.0973 Y49.4062

N256 X5.1243 Y49.4288

N258 X5.1481 Y49.4433

N260 X5.1737 Y49.454

N262 X5.2004 Y49.4608

N264 X5.2277 Y49.4636

N266 X5.255 Y49.4623

N268 X5.2816 Y49.4572

N270 X5.3071 Y49.4483

N272 X5.331 Y49.4359

N274 X5.354 Y49.4193

N276 X5.3709 Y49.4037

N278 X6.0592 Y48.6949

N280 X6.0818 Y48.6679

N282 X6.0963 Y48.6441

N284 X6.107 Y48.6185

N286 X6.1138 Y48.5918

N288 X6.1166 Y48.5645

N290 X6.1153 Y48.5372

N292 X6.1102 Y48.5106

N294 X6.1013 Y48.4851

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N298 X6.0723 Y48.4382

N300 X6.0567 Y48.4213

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N308 X5.2715 Y47.6852

N310 X5.2448 Y47.6784

N312 X5.2175 Y47.6757

N314 X5.1902 Y47.6769

N316 X5.1636 Y47.682

N318 X5.1381 Y47.6909

N320 X5.1142 Y47.7033

N322 X5.0912 Y47.7199

N324 X5.0743 Y47.7355

N326 Z.1 F500.

N328 G0 Z1.25

N330 M5

N332 G53 Z0.

N334 M30

%

[Matthew Hajicek - Singularity]

Ployd,

[Ployd]

Matt,

[Matthew Hajicek - Singularity]

Ployd,

 

I stuck your code in a backplotter, and it looks smooth and straight. My guess would be that your router is moving sloppily, perhaps feeding to fast. As far as post settings, your code is interpolating the arcs instead of using G2 and G3. Your router may or may not have a better ability to handle curves in arc mode. You may find some success in slowing down the feedrate in corners too.

[Ployd]

Matt,

 

Thanks for taking the time to help. Here is another section of code where I have the I and J and the G2 interpolating you referred to.

 

I tried slowing down the feed to 30% and it didn't make a huge difference. Thanks for running the code through your backplotter. I'm not discounting your theory on feed rate and slop, but we can't run it too slow or we wouldn't make any money on cutting out parts.

 

As far as I know there isn't a way to slow feed rate on short curvey sections and full bore on straighter sections (within in your code, unless manually editing). We don't have a person at the controller manually adjusting feed rate.

 

; CUT OUT

N180 X93.4596 Y13.8155

N182 Z1.1

N184 G1 Z.5 F40.

N186 X90.5422 F600.

N188 X90.4735 Y13.8245

N190 X90.3991 Y13.8551

N192 X90.3358 Y13.9026

N194 X90.2902 Y13.9595

N196 X90.2752 Y13.9883

N198 X90.2676 Y14.0016

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N202 X90.267 Y13.9973

N204 Y13.

N206 G2 X90.0795 Y12.8125 I-.1875 J0.

N208 G1 X87.5825

N210 X87.2075

N212 X86.8325

N214 G2 X86.645 Y13. I0. J.1875

N216 G1 Y75.

N218 G2 X86.8325 Y75.1875 I.1875 J0.

N220 G1 X87.2075

N222 X87.5825

N224 X90.3945

N226 G2 X90.5809 Y75.0201 I0. J-.1875

N228 G1 X90.5827 Y75.0031

N230 X90.5829 Y75.0038

N232 X90.5833 Y75.0112

N234 G2 X90.7705 Y75.1875 I.1872 J-.0112

N236 G1 X93.5825

N238 G2 X93.77 Y75. I0. J-.1875

N240 G1 Y67.1155

N242 X93.7607 Y67.0458

N244 X93.7293 Y66.9706

N246 X93.6805 Y66.907

N248 X93.6184 Y66.8584

N250 X93.5474 Y66.8272

N252 X93.4811 Y66.816

N254 X93.4596 Y66.8155

[George Gerhard]

Ployd

this is your machine. Throw an indicator on each axis and check backlash first. You may just have something loose. ie; belt or pulley.

 

good luck

George

[Ployd]

Yeah, we need to go through the machine and check it out. We keep up on the machine maintenance and laser calibration. Probably time to get someone out here and give it a once over.

 

Here is the code after running it through HighFeed. This may help us out next time we run some sheet goods. Anyone else using the HighFeed option? I like the looks of the feed output but I will have to give it a try and see how it goes.

 

% HF , MX ,

; PROGRAM - T

; DATE - 29-11-08 TIME - 16:40

N100 G70

N102 G0 G17 G40 G80 G90

N104 G53

N106 M73

; CONTOUR

; T2 .375 X 6.961 C FEM TOOL - 2 PIVOT LEN. - 16.73

N108 T2

N110 M6

N112 S9000

N114 M3

N116 G54

N118 G0 G90 B0. C0.

N120 X8.2418 Y51.6718

N122 G43

N124 Z1.25

N126 G51 A75 E0.030

N128 Z1.1

N130 G1 Z.5 F40.

N132 X8.2347 Y51.7292 F5.

N134 X8.204 Y51.8048 F25.

N136 X8.1559 Y51.8688 F45.

N138 X8.0943 Y51.918 F65.

N140 X8.0235 Y51.9498 F85.

N142 X7.9576 Y51.9617 F105.

N144 X7.9372 Y51.9624 F125.

N146 X7.7551 Y51.9651 F145.

N148 X7.5729 Y51.9677 F165.

N150 X7.3908 Y51.9704 F185.

N152 X7.2086 Y51.9731 F205.

N154 X7.0265 Y51.9757 F225.

N156 X6.8443 Y51.9784 F245.

N158 X6.6621 Y51.9811 F265.

N160 X6.48 Y51.9837 F285.

N162 X6.2978 Y51.9864 F265.

N164 X6.1157 Y51.9891 F245.

N166 X5.9335 Y51.9917 F225.

N168 X5.7514 Y51.9944 F205.

N170 X5.5692 Y51.9971 F185.

N172 X5.387 Y51.9997 F165.

N174 X5.2049 Y52.0024 F145.

N176 X5.0227 Y52.0051 F125.

N178 X4.9539 Y51.997 F105.

N180 X4.8791 Y51.9676 F85.

N182 X4.8151 Y51.921 F65.

N184 X4.7687 Y51.8647 F45.

N186 X4.7532 Y51.8361 F25.

N188 X4.7455 Y51.823 F5.

N190 X4.7453 Y51.8236

N192 X4.7449 Y51.8292 F25.

N194 X4.7474 Y51.994 F45.

N196 X4.7498 Y52.1587 F65.

N198 X4.7522 Y52.3234 F85.

N200 X4.7546 Y52.4881 F65.

N202 X4.757 Y52.6528 F45.

N204 X4.7594 Y52.8175 F25.

N206 X4.7605 Y52.8261 F5.

N208 X4.7619 Y52.8242

N210 X4.768 Y52.8117 F25.

N212 X4.7958 Y52.7636 F45.

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N216 X4.8867 Y52.6793 F85.

N218 X4.9594 Y52.6473 F105.

N220 X5.0262 Y52.6363 F125.

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N248 X7.7749 Y52.5958 F165.

N250 X7.957 Y52.5932 F145.

N252 X8.0268 Y52.6014 F125.

N254 X8.1025 Y52.6318 F105.

N256 X8.1669 Y52.6795 F85.

N258 X8.2163 Y52.7409 F65.

N260 X8.2486 Y52.8115 F45.

N262 X8.2607 Y52.8773 F25.

N264 X8.2615 Y52.8958 F5.

N266 Z.6

N268 G0 Z.75

N270 X8.2418 Y51.6718

N272 Z.6

N274 G1 Z0. F40.

N276 X8.2347 Y51.7292 F5.

N278 X8.204 Y51.8048 F25.

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N282 X8.0943 Y51.918 F65.

N284 X8.0235 Y51.9498 F85.

N286 X7.9576 Y51.9617 F105.

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N290 X7.7551 Y51.9651 F145.

N292 X7.5729 Y51.9677 F165.

N294 X7.3908 Y51.9704 F185.

N296 X7.2086 Y51.9731 F205.

N298 X7.0265 Y51.9757 F225.

N300 X6.8443 Y51.9784 F245.

N302 X6.6621 Y51.9811 F265.

N304 X6.48 Y51.9837 F285.

N306 X6.2978 Y51.9864 F265.

N308 X6.1157 Y51.9891 F245.

N310 X5.9335 Y51.9917 F225.

N312 X5.7514 Y51.9944 F205.

N314 X5.5692 Y51.9971 F185.

N316 X5.387 Y51.9997 F165.

N318 X5.2049 Y52.0024 F145.

N320 X5.0227 Y52.0051 F125.

N322 X4.9539 Y51.997 F105.

N324 X4.8791 Y51.9676 F85.

N326 X4.8151 Y51.921 F65.

N328 X4.7687 Y51.8647 F45.

N330 X4.7532 Y51.8361 F25.

N332 X4.7455 Y51.823 F5.

N334 X4.7453 Y51.8236

N336 X4.7449 Y51.8292 F25.

N338 X4.7474 Y51.994 F45.

N340 X4.7498 Y52.1587 F65.

N342 X4.7522 Y52.3234 F85.

N344 X4.7546 Y52.4881 F65.

N346 X4.757 Y52.6528 F45.

N348 X4.7594 Y52.8175 F25.

N350 X4.7605 Y52.8261 F5.

N352 X4.7619 Y52.8242

N354 X4.768 Y52.8117 F25.

N356 X4.7958 Y52.7636 F45.

N358 X4.8286 Y52.7254 F65.

N360 X4.8867 Y52.6793 F85.

N362 X4.9594 Y52.6473 F105.

N364 X5.0262 Y52.6363 F125.

N366 X5.0431 Y52.6358 F145.

N368 X5.2252 Y52.6332 F165.

N370 X5.4074 Y52.6305 F185.

N372 X5.5895 Y52.6278 F205.

N374 X5.7716 Y52.6252 F225.

N376 X5.9537 Y52.6225 F245.

N378 X6.1358 Y52.6198 F265.

N380 X6.318 Y52.6172 F285.

N382 X6.8643 Y52.6092 F265.

N384 X7.0464 Y52.6065 F245.

N386 X7.2286 Y52.6038 F225.

N388 X7.4107 Y52.6012 F205.

N390 X7.5928 Y52.5985 F185.

N392 X7.7749 Y52.5958 F165.

N394 X7.957 Y52.5932 F145.

N396 X8.0268 Y52.6014 F125.

N398 X8.1025 Y52.6318 F105.

N400 X8.1669 Y52.6795 F85.

N402 X8.2163 Y52.7409 F65.

N404 X8.2486 Y52.8115 F45.

N406 X8.2607 Y52.8773 F25.

N408 X8.2615 Y52.8958 F5.

N410 Z.1

N412 G0 Z1.25

N414 M5

N416 G53 Z0.

N418 M30

%

[NEW2007]

Add G61(-exact stop) may help

 

Eric P

[CNC PRO]

quote:

---

T2 .375 X 6.961

---

Is 6.961 the total length of tool & holder, or is it the protruding tool length?

 

What type of tool are you using? #of flutes, carbide tipped or solid carbide..etc.

 

Also it looks like 3/4" plywood...correct??

 

Reason I ask is cause that looks like an awful high feed rate with a low RPM, for a 3/8dia. tool of that length (if that is the length) to be cutting plywood.

 

Correct me if I am wrong or not getting something.

[Ployd]

6.961 is tool and holder.

 

Using two flute Onsrud carbided cutter.

 

1" MDO plywood and cut 2) 1/2" deep passes

 

We run the RPM's around 16000 with a feed rate set at about 50%

 

When you receive drawings from a customer do you ever convert the geometry to a uniform geometry type such as spline, arc, line, etc?

[CNC PRO]

Was thinking that the chamfer edges could be from tool bending due to higher feed rate then tool could handle, and or as Matt suggested…a sloppy machine could be a likly factor as well.

 

 

I ran your code thru my back-plotter as well, with the same results as Matt’s.

 

quote:

---

When you receive drawings from a customer do you ever convert the geometry to a uniform geometry type such as spline, arc, line, etc?

---

We redraw everything in Inventor, then bring it into Mastercam (standard around here) Though occasionally I’ll still get splines that I retrace with lines and arcs. With splines my machines slow to a crawl on small curves and go crazy fast on bigger ones...with no control over it (other then manual), I try not to use splines if I don’t have too.

[Ployd]

I have never liked using splines unless your trying to create a loft or sweep. Our machine also slows down to a crawl sometimes on curved parts. Redrawing the geometry is probably a good idea right off the bat to save time later. The simplify command does not always convert splines to curves and arcs which is frustraring. I always liked the explode command in AutoCAD.

[Gov'ner]

Ployd,

 

Not sure if you have figured this out yet or not but... Could your workpiece be sliding around a little? I have seen this type of problem where the board moves slightly during cutting.

[Matthew Hajicek - Singularity]

It could also potentially be a matter of servo tuning.

[Ployd]

I don't think the material is moving in this case.

 

I'm not familiar with servo tuning. How is this done and how do you know if the servo needs tuned.

 

We are leaning towards the y axis.

[Greg VN]

I have a 5 axis Anderson with a Fanuc 16m controller. A lot of the work we do is in 3 axis. If I don't have a G08 (advanced preview control enable) in the program I get some of those same issues. What brand cnc are you doing this with?

[Ployd]

We have a Quintax 5-axis with ***or controller.

[Gov'ner]

Do you get the same quality of cut if you raise the cutter up and only cut 1/8" deep into the board?

[Ployd]

We don't really cut panels too often. We maybe cut a 100 panels a month or every couple of months. Next time we cut panels we will run some tests. Mostly cut fiberglass.

[Tom Dorgan from American Precision]

Ployd, your E is too loose.

Change the E 0.030 to E .001 and see if that makes a difference.

I would also change the A on the same line

from A .75 to A 100.0

 

N126 G51 A75 E0.030

 

CHANGE TO

 

N126 G51 A100 E.001

[Ployd]

Thanks, Tom

 

What is the A and E setting? Is that controlled from my post or when I set up my program in MC?

[Thermoform Guy]

Ployd,

 

We have a couple of different routers at our

shop and I have notice this before on our 3 axis

Onsrud. I changed in the toolpath parameters from

roll around all corners to none. This seem to

help and I was able to hold the same feed rates.

I don't know if this is the proper fix but it

help me.

 

Hope this helps

Dave

[heeler]

Ployd,

 

From the ***or manual,

Look-Ahead (G51)

Programming Format is G51 [A] E

 

A(0-255) Is optional and it defines the percentage of acceleration to be applied. When not programed or programmed with a "0" value the CNC assumes the acceleration value se by machine parameter for each axis.

 

E(5.5) Maximum contouring error allowed.

 

We program ours as G51 E.0001 when cutting aluminum. As you see we don't even use the "A". The value is hard coded in our post in the contour control stuff. You could just manually change it at first and see what works best for what you are doing.

 

HTH

 

Glenn