torch moving away from plate

[funkygaeden]

Hi guys,
I'm just starting out and trying to work thru some problems.
The first test piece I made cut great. But ever since every time I try and cut from any other gcode I've produced,
the torch head starts raising up during mid cut. I've spent hours trying to figure it out and it's driving me crazy.
Have a look at these two pieces (making garden stakes for the wife)
The 'Hope' design was the first one I made and it cuts great every time.

hope.jpg (85.33 KiB) Viewed 2680 times

hope.jpg (85.33 KiB) Viewed 2680 times

The 'Love' design (and everything else ive made since) starts out great but then the torch starts moving
away from the place creating a long arc that just melts the plate.

love.jpg (79.42 KiB) Viewed 2680 times

love.jpg (79.42 KiB) Viewed 2680 times

(Yes, I do have the THC enabled)

Here's the GCODE for the 'Love tap' file with the problem if that helps.
Thanks in advance guys!!
Dan

N0001 (Filename: love.tap)
N0011 (Post processor: MP3000-DTHCII+scriber2.scpost)
N0021 (Date: 22/06/2015)
N0031 G20 (Units: Inches)
N0041 F1
N0051 G53 G90 G40
N0061 S10 (DTHC is off)
N0071 (Part: love)
N0081 (Operation: Inside Offset, heartinside, T2: HT-45 {45 amp} 16ga Steel .060)
N0091 (tool number: 2 Feedrate: 350)
N0101 (No Stored DTHC parameters in this POST)
N0111 G00 Z0.3937
N0121 X2.8539 Y1.8603
N0131 Z0.1500
N0141 G28.1 Z0.12 F19.685
N0151 G92 Z0.0
N0161 G00 Z0.3937
N0171 G92 Z0.0
N0181 G00 Z0.1500
N0191 M03
N0201 G01 Z0.0600 F60.0
N0211 G03 X2.8338 Y1.7489 I0.0456 J-0.0657 F350.0
N0221 S20 (DTHC is on)
N0231 G01 X3.3284 Y1.0300
N0241 X3.3355 Y1.0407
N0251 X3.3360 Y1.0414
N0261 G02 X3.4061 Y1.1332 I1.3696 J-0.9730
N0271 X3.5198 Y1.2667 I3.0520 J-2.4849
N0281 X3.6956 Y1.4589 I6.5726 J-5.8366
N0291 X3.9747 Y1.7501 I15.7081 J-14.7765
N0301 G01 X4.2773 Y2.0602
N0311 X4.4124 Y2.2007
N0321 G03 X4.5374 Y2.3372 I-3.0764 J2.9411
N0331 G01 X4.5378 Y2.3376
N0341 G03 X4.7959 Y3.0238 I-0.7318 J0.6670
N0351 G01 Y3.0243
N0361 G03 X4.6425 Y3.3453 I-0.4115 J0.0004
N0371 X3.7832 Y3.2514 I-0.3630 J-0.6576
N0381 G01 X3.7352 Y3.2062
N0391 X3.6680 Y3.1387
N0401 G02 X3.4878 Y3.0021 I-0.4574 J0.4162
N0411 G01 X3.4845 Y3.0007
N0421 X3.4314 Y2.9824
N0431 G02 X3.4095 Y2.9843 I-0.0088 J0.0255
N0441 G01 X3.4087 Y2.9848
N0451 G02 X3.3962 Y2.9996 I0.0131 J0.0236
N0461 G01 X3.3516 Y3.1291
N0471 X3.3514 Y3.1296
N0481 G03 X3.1736 Y3.4955 I-1.3969 J-0.4528
N0491 G01 X3.1732 Y3.4960
N0501 G03 X2.7061 Y3.7641 I-0.4897 J-0.3124
N0511 X2.2803 Y3.4048 I0.0487 J-0.4897
N0521 X2.2923 Y2.7590 I1.0595 J-0.3033
N0531 G01 X2.2925 Y2.7585
N0541 G03 X2.6693 Y1.9923 I2.5663 J0.7865
N0551 G01 X2.6699 Y1.9915
N0561 G03 X2.8338 Y1.7489 I9.6782 J6.3642
N0571 (Operation: Outside Offset, Colour 179, T2: HT-45 {45 amp} 16ga Steel .060)
N0581 M05
N0591 G00 Z0.3937
N0601 X2.5888 Y0.1197
N0611 Z0.1500
N0621 G28.1 Z0.12 F19.685
N0631 G92 Z0.0
N0641 G00 Z0.3937
N0651 G92 Z0.0
N0661 G00 Z0.1500
N0671 M03
N0681 G01 Z0.0600 F60.0
N0691 G03 X2.5088 Y0.1997 I-0.0800 J0.0000 F350.0
N0701 S20 (DTHC is on)
N0711 G01 X2.4818
N0721 X0.0005
N0731 G02 X-0.0265 Y0.2267 I0.0000 J0.0270
N0741 G01 X-0.0270 Y4.7502
N0751 G02 X0.0000 Y4.7772 I0.0270 J0.0000
N0761 G01 X0.9780
N0771 G02 X1.0050 Y4.7502 I0.0000 J-0.0270
N0781 G01 X1.0052 Y1.1381
N0791 X1.7897
N0801 G02 X1.6125 Y1.3950 I1.7664 J1.4075
N0811 X2.4080 Y4.5033 I1.9547 J1.1557
N0821 X5.3710 Y3.7523 I1.0982 J-1.8877
N0831 G01 X5.2533 Y4.5654
N0841 X5.2437 Y4.6330
N0851 G02 X5.2705 Y4.6638 I0.0267 J0.0038
N0861 G01 X6.0904
N0871 G02 X6.1172 Y4.6402 I0.0000 J-0.0270
N0881 G01 X6.5620 Y1.1242
N0891 X7.6550 Y4.4485
N0901 X7.6558 Y4.4505
N0911 X7.6563 Y4.4517
N0921 G02 X7.6812 Y4.4682 I0.0249 J-0.0105
N0931 G01 X10.8724
N0941 X11.0000 Y4.4681
N0951 G02 X11.0270 Y4.4411 I-0.0000 J-0.0270
N0961 G01 Y3.7642
N0971 G02 X11.0000 Y3.7372 I-0.0270 J0.0000
N0981 G01 X9.0867
N0991 X9.0868 Y2.8464
N1001 X10.7076
N1011 G02 X10.7346 Y2.8194 I-0.0000 J-0.0270
N1021 G01 X10.7345 Y2.1205
N1031 G02 X10.7075 Y2.0935 I-0.0270 J0.0000
N1041 G01 X9.0868
N1051 X9.0867 Y0.8394
N1061 X10.7076 Y0.8392
N1071 G02 X10.7346 Y0.8122 I-0.0000 J-0.0270
N1081 G01 Y0.0000
N1091 G02 X10.7076 Y-0.0270 I-0.0270 J0.0000
N1101 G01 X8.2890
N1111 G02 X8.2620 Y-0.0002 I-0.0000 J0.0270
N1121 G01 X8.2421 Y3.3063
N1131 X7.1850 Y-0.0079
N1141 G02 X7.1592 Y-0.0267 I-0.0257 J0.0082
N1151 G01 X5.9413 Y-0.0270
N1161 G02 X5.9146 Y-0.0039 I-0.0000 J0.0270
N1171 G01 X5.6314 Y1.9530
N1181 G02 X5.4520 Y1.4954 I-2.1808 J0.5909
N1191 X2.5089 Y0.5461 I-1.9462 J0.9971
N1201 G01 X2.5088 Y0.2267
N1211 Y0.1997
N1221 M05
N1231 G00 Z0.3937
N1241 X0.0000 Y0.0000
N1251 S900
N1261 M22
N1271 S10 (DTHC is off)
N1281 M22
N1291 M05 M30

[WyoGreen]

The one thing I'm not finding is the pre-set volts in your tap file. Usually when the torch rises up, it's trying to raise the detected torch volts to the pre-set volts. You might compare the pre-set volts on your Mach screen with the actual volts displayed on the Mach screen. You also may want to compare the tap file that works with the tap file that doesn't work to see what changes set up wise, which is about the first dozen lines or so.

Steve

[Capstone]

I agree with Wyo,

90% chance this issue has something to do with using the correct POST processor in Sheetcam for your Digital Torch Height Control system

[Sampson Jones]

I've been dealing with the exact same thing for a long time and have yet to figure it out ,over six months . Problem is its intermitten , not all the time . Interesting preset volts in Mach pointer .Ill check mine out . Would bad air do this ? I have a home made refrigerator air dryer , but man it's real humid here now. If anybody could do a check list elimination punch list for this problem .I.m sure it would help out some of us .

[Sampson Jones]

Another question . Where is the torch preset volts applied to the g code ? I would assume its done in sheet cam ? I cant find anywhere in sheetcam that this is done . Now, in mach on the control screen, preset volts is displayed and can be run up or down . Thats where Ive been setting my preset volts at just before I hit the run button in mach . Could someone explain this ?

[acourtjester]

It is in the tool setup in SheetCam

volts.jpg (39.67 KiB) Viewed 2576 times

volts.jpg (39.67 KiB) Viewed 2576 times

[Sampson Jones]

What the heck is going on here ? I knew in three years of cutting ,I've never ever seen the boxes to enter that . Here is all I see when I open the jet cutting tool box . Notice several boxes are missing . I have sheet cam development and sheet cam tng loaded on my computer . Both versions are missing those boxes . Thanks Jester , we now may be getting to my long mysterious problem .

image.jpg (18.2 KiB) Viewed 2552 times

image.jpg (18.2 KiB) Viewed 2552 times

[acourtjester]

If you copy this file to /sheetcam/TOOlSets in your SheetCam-CandCNC folder then you should be able to bring it into SheetCam by going to the "file" menu then to "open toolset" and click on that file it will put that info in you tools section. You should be able to edit it tool by tool as this is for the PM 65 not sure if some of the spects will be different for a PM45. After you have done your edit save it as "default toolset" or a name you choose and you will have it for later use. I'm not sure if the path rules are in this file but you can also edit them for your use. If you don't use them make sure you select "None" so they are not included into you Gcodes.

Hy-Ther-65 delay added 1.5 sec.tools A torch off at end.zip

(1.5 KiB) Downloaded 109 times

Hy-Ther-65 delay added 1.5 sec.tools A torch off at end.zip

(1.5 KiB) Downloaded 109 times

[acourtjester]

Here is what the path rules menu looks like at the bottom you can see how you select the rule set you what to use or NONE.

[Sampson Jones]

Jester , i did what you suggested but,I'm still missing the last four boxes on the jet tool chart . Missing are these check off boxes , pre set volts , dthc -sec,tip size amps , no dthc 0
I really appreciate your help , but still trying to figure this one out . I have emailed Les at sheetcam .

[Sampson Jones]

What I see

[tcaudle]

on the first issue:
1 350IPM? Seems a bit fast for 16Ga with 45 A
2 That post has no Dynamic Cut Control (automatic settings) in it but turning on and off the DTHC You have to manually set the cut parameters in the Cut Profile menu. you can have various stored settings but you have to remember to select them prior to cutting
3. If it lifts up the DTHC is trying to INCREASE the voltage. You need to do the cut with the DTHC (THC) button OFF and watch the TORCH VOLTS The Preset Volts tells it what to try and increase / decrease the voltage to. You cannot SET the voltage you can one set what you want the voltage to be to achieve the arc gap
4. The DCC settings you are seeing for the tool table in SheetCAm comes FROM the POST. One of the neat things about SheetCAM is you can put things in the post that alter the SheetCAM interface and add values. To take advantage of the feature you have to be running SheetCAM 6.0.14 or later and use the DTHC-HYT-TAP_SoftPierce+Marker-rev11D.zip post or the later post ending in 11J. There is a SheetCAm support installer on the website/downloads that will update your POSTS and has new expanded toolsets for the Hypertherm.

The DTHC will tell you what it is trying to do. It just won't tell you why. It is following a simple set of rules that says: Raise the torch to raise the voltage; Lower the torch to lower the voltage. Voltage = height but the chart values ONLY work if you are using the recommended feedrate, the exact consumables and you have good workclamp connection to the MATERIAL and clean dry air.
Do not doggedly try to force the Torch Volts to match the chart if it cuts at the wrong height.

There are UP and DOWN indicators , Torch volt indicators and the ARC OK and DTHC ONLINE .

[Sampson Jones]

HOLY CRAP ! The boxes I was missing are in the post Thanks Tom ! I loaded the one you suggested and it was all there ! Now let's see if a two year problem will be cured , I'll keep y'all posted . Thanks Jester ! I did not mean to hijack this thread but we had the same problem

[Sampson Jones]

ALL right need clarification on what these boxes mean in sheet cam edit tool."Pre set current" in sheet cam that box has 40 in it for 10 ga. My hypertherm manual says "Arc Current" 10 ga is 45 . Next is a box in sheetcam tools that says "tip size -amps " , clarification on these anyone ?

I m sorry to report my sheet run with the newly loaded "dthy-hyt-tap_softpierce+marker-rev11d edited was a failure . I had to shut it down due to multiple lift ups . I changed consumables twice . I run a home built refrigriated air dryer . I did a air hole blower test on card board and the air appeared dry . Thanks

[tcaudle]

Preset Current ONLY WORKS if you have the RS485 serial port option on your Hypertherm and the Hyt-Connect RS485 kit on the electronics. It lets you select the cut current and air pressure remotely (or change the value DURING a cut) Ignore it if you don't have that feature.

Torches go up because they see the voltage dropping and their job is to try and hold it at the PRESET VOLTS value. The higher the torch (Arc Gap) the higher the voltage.

When it starts to climb click off the DTHC and then watch the TORCH volts. If they are going down then something is either wrong with the voltage pickup or the digital voltage probe (PWM module) or the material is warping up and getting closer to the torch tip.

The THC only has torch volts to use to "measure" the height. If they are not right then neither will be the height it picks. I have seen this and it was caused by a bad CAT5 cable out to the PWM Module. A couple of times the internal divider was the problem

You can send the PWM in and have it checked and calibrated