Delcam User Forum

PowerMILL :: RE: POP QUIZ

Author: sbeyke
Posted: Sat Jul 05, 2008 2:44 pm (GMT 0)
Topic Replies: 23

NATHAN and MH,

Attached please find a zipped project file.

All toolpaths and the stockmodel are invalidated.

Load the project and batch process.

Please let me know your results, and your thoughts.

Best regards,
Steven

This time the upload was successful. Perhaps a size limit has been preventing me from uploading projects. Sorry for the calculation time required, but you know how those stock models are....
_________________
Imagination is more important than knowledge -Einstein

PowerMILL :: RE: POP QUIZ

Author: sbeyke
Posted: Sat Jul 05, 2008 10:58 am (GMT 0)
Topic Replies: 23

Nathan and MH,

After the first tool is used, a "thicker than" value of .015" is used for the tools with the short overhang. A "thicker than" value of .025" is used for the tool with the longer overhang. My thinking is that the extra .010" of "thicker than" should help eliminate "picking" at cusp. "Remove cusps" is also turned off in the longer overhang but is turned on in the shorter tool.

The one thing I will try today is to increase the "THICKNESS" value of the longer overhang to equal the sorter overhang plus machining tolerance. Maybe this will add a little filtering.

I tried to post a ZIPPED project, but the forum returned an error and would not let me. This is becomming a common occurance.

MH, I would like to send you the project if you don't mind. Take a look and tell me if you see anything strange or unusual.

Awhile back, one of the DELCAM staff suggested setting the mesh of the stock model to the "radius" of the smallest tool. This would be a starting point, and could be adjusted as needed. As I understand, these stockmodel wireframes have a triangulated mesh calculated over them to smooth out the surface of the stockmodel.

Nathan, did you get a reliable email working so that I can send you projects? If not, how could I send you this example?

Best regards,
Steven
_________________
Imagination is more important than knowledge -Einstein

PowerMILL :: RE: POP QUIZ

Author: MH
Posted: Sat Jul 05, 2008 10:44 am (GMT 0)
Topic Replies: 23

I have never had any areas re-cut or very little if any air cutting, My stock models for roughing are usually made with a .0015 tolerance and a .015-.025 step or mesh as you might call it, this might be a little overkill, I know the default is like .05, this leaves too large of cusps in my opinion. Depending on the size of the model I am cutting, I will loosen things up a bit on the bigger stuff. Most of my roughing toolpaths are with a .002 -.0025 machining tolerance, my rest roughing are with a slightly tighter tolerance, .0015-.002 giver or take. My detect material is usually right about .008-.010 and I never expand the toolpath, or at least very very seldom. using those settings I would think it should not see that stock with the longer tool, my guess is that you are detecting the remaining cusps somehow and pm thinks it's actually material. One thing I might add, I never create a shank on my ROUGHING tools, I make the cutting area and then go right into the holder. I have seen some strange results when roughing with a tool like in this pic..

PowerMILL :: RE: POP QUIZ

Author: ncheung
Posted: Sat Jul 05, 2008 6:42 am (GMT 0)
Topic Replies: 23

Steven,

When stock model referencing what do you have

'Detect material thicker than' set as.

Some times even adding to that value by a small amount such as 0.1mm (0.004") could reduce some of the extra cuts that you are seeing.

I would definetly recommend using the stock model as I never encounter fresh air cutting and use this method daily.

Hope all is well.

Nathan

P.S. Off topic but did you get my surface app to work?

PowerMILL :: RE: POP QUIZ

Author: sbeyke
Posted: Sat Jul 05, 2008 12:19 am (GMT 0)
Topic Replies: 23

MH wrote:

All my roughing toolpaths are applied to the stock model, and rest roughing programs are only referenced to the stock model, this is the only way I will do it, yes it can be a pain in the ass to have toolpaths locked to it, and it takes longer, but the end result is well worth it.

MH,

I took your advice and tried some toolpaths using stock model reference.
I was also eager to try something that I have not been able to do with toolpath reference.

Without going into all the details, it is my understanding that if I were to create a stockmodel from a BLOCK of stock and a toolpath, then I would have a fairly accurate representation of the machining results. I could then reference that stockmodel with a new cutter and be able to cut stock that is accesible to the new cutter.

FLASHBACK:
A year or so ago, I tried to create some area clearance toolpaths using toolpath reference. I ran into an issue with auto collision detection holding the cutting edges away from the model. I had several hours of air cutting, and only a few minutes of cutting metal. It was explained that this was expected behavior, and that a stock model was the prefered way.

So, taking your advice, I created this project. My goal was to create a roughing strategy using several different tools with both short and long overhangs for each tool. By all I know, this should not violate any DELCAM guidelines. Each tool has the same, or smaller diameter as the tool before it, and also the same or smaller tip rad as is required for rest roughing using toolpath reference. This should not be necessary for stock model reference.

My problem is that in almost every case, the tool with the longer overhang calculates cutter paths that should not be necessary. By this I mean that the tool with the shorter overhang should have removed the stock that the longer overhang is trying to cut.

EXAMPLES:

STOCK_1.JPG shows a sample DELCAM model I used in this project.

STOCK_4A.JPG shows toolpaths calculated with tool 4 after larger tools were calculated and applied. This is the tool with the short overhang. This toolpath is then applied to the stockmodel.

STOCK_4B.JPG shows the toolpath calcualted using the same tool with the longer overhang. The cut areas were very close to the top of the part and should have been cut with the cutter used in "4A".

STOCK_7A.JPG shows tool 7 with the short overhang. Again, the path is applied.
STOCK_7B.JPG shows tool 7 with the long overhang. AGAIN it found stock to cut that the shorter overhang should have cut.

I have experimented trying to get the longer overhang to overlook minute amounts of stock by increasing the "thicker than" value, but it did not seem to have any effect.

Toolpath PARAMETERS:
Tool diameters 0.750", 0.500", .0375", 0.250", 0.1875", 0.125"
Thickness 0.030"
Machining Tolerance 0.003"

Stockmodel Parameters
Tolerance 0.002"
Stepover value 0.040"
Rest thickness 0.0

If any of you have any suggestions, please peak up. Area Clearance with toolpath reference did not cut it. Area Clearance with stockmodel reference tries to cut it twice. Maybe there is some way to average this out????

Best regards,
Steven
_________________
Imagination is more important than knowledge -Einstein

PowerSHAPE :: RE: Exporting module to Powermill 8 (Powershape v7) Problem

Author: a1moldmaker
Posted: Fri Jul 04, 2008 10:55 pm (GMT 0)
Topic Replies: 15

thanks JonH
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Thanks
Bruce Green

WinXP64 bit pro Intel Core@Extreme Q6800@ 2.93GHz 8 gig ram Nvidia Quadro FX1700
We use Powermill,Powershape,PSMoldmaker,PSElectrodemaker
http://www.4shared.com/file/38525491/5085da13/NC_Fadal_V13.html?dirPwdVerified=4ea7fe97

PowerSHAPE-e :: RE: Graphics card problem... I guess?

Author: pairair
Posted: Fri Jul 04, 2008 8:02 pm (GMT 0)
Topic Replies: 4

Thank you, I've tried the "software picking" thing earlier and it made no difference as far as I can tell. I guess I'll just have to live with it on this computer.

Pär

PowerMILL :: RE: cycle times

Author: girish
Posted: Fri Jul 04, 2008 11:41 am (GMT 0)
Topic Replies: 13

Steve,
There is a bit of problem when Rapid and cutting feed rates are made same,It happenned to me a while ago,I noticed that the machine keeps cuting in G0

Girish.

PowerSHAPE-e :: RE: Graphics card problem... I guess?

Author: John Murphy
Posted: Fri Jul 04, 2008 9:52 am (GMT 0)
Topic Replies: 4

Nathan, occasionally I get this on larger models, usually a view/rebuild allows me to continue, and I can pick anything again. John

PowerSHAPE-e :: RE: Graphics card problem... I guess?

Author: ncheung
Posted: Fri Jul 04, 2008 9:36 am (GMT 0)
Topic Replies: 4

JonH wrote:

Locate the file 'PowerSHAPE.con' which is in

.............\PowerSHAPE7350\sys\misc

Open the file in Wordpad and locate the section that reads-

# Software picking
# Picking is done in hardware by default. Uncommenting this
# resource may solve some picking-related problems.
#software_picking: yes

Change the last line of that block to

software_picking: yes

and save the file.

This should get the IC running OK, but I doubt it will affect the grid.

Jon

I have noticed recently that I am sometimes unable to select items in powershape by either box or picking. Even whacking escape a few time does nothing

Unfortunately it is very hit and miss when it happens, but turning the IC off then on cures it

Have you come across this and do you think it is worth me trying the above fix?

Running 7.3.50 sp2

Nathan

PowerSHAPE :: RE: Out of Memory Error

Author: JonH
Posted: Fri Jul 04, 2008 6:47 am (GMT 0)
Topic Replies: 1

Hi Raj

I'm afraid the only answer is to add more physical memory to the machine. If you are running XP and already have 2Gb of RAM, then please contact your local support office. You may need help setting XP to use more.

PowerSHAPE :: RE: Exporting module to Powermill 8 (Powershape v7) Problem

Author: JonH
Posted: Fri Jul 04, 2008 6:44 am (GMT 0)
Topic Replies: 15

I will pass this matter to development for their attention.

PowerSHAPE-e :: RE: Graphics card problem... I guess?

Author: JonH
Posted: Fri Jul 04, 2008 6:42 am (GMT 0)
Topic Replies: 4

This does sound like a graphics card issue. We usually advise people to stick to the Nvidia chips as they tend to work best with PowerSHAPE. One thing you could try, is to turn hardwar picking off.

Locate the file 'powershape.con' which is in

.............\PowerSHAPE7350\sys\misc

Open the file in Wordpad and locate the section that reads-

# Software picking
# Picking is done in hardware by default. Uncommenting this
# resource may solve some picking-related problems.
#software_picking: yes

Change the last line of that block to

software_picking: yes

and save the file.

This should get the IC running OK, but I doubt it will affect the grid.

PowerMILL :: RE: cycle times

Author: sbeyke
Posted: Thu Jul 03, 2008 10:12 pm (GMT 0)
Topic Replies: 13

Wrecker1,

Another thing to look at is how your links are set up.

For example, if the majority of your liinks are "skim" then it is likely your tool stays down in the part and "vector rapids" at feedrate. That is, the move between segments is done at a feedrate equal to the rapid feedrate you selected. This is done to ensure the tool follows a known path between segements.

Summarizing all that has been posted above:

1. Ensure that your setup sheets use the proper variables. These have changed over the years between versions. A little tweeking may be necessary.

2. Ensure that the proper rapid rates are included in your toolpaths. These rates vary from machine to machine, so you might need a macro to get "best guess" for each type machine tool.

3. Experiment with leads and links. Change the incremental plunge value to get the tool closer to the start point when possible.

4. Run tests on your machines to determine actual performance. Create several cutterpaths that vary in cuts and rapids. By changing the cutting feedrate, you can calculate the error in your rapid moves.

Be advised that the error you see in a single path will not accurately represent all paths. For example, a Constant-Z toolpath cutting a large cavity with spiral option may be very close to actual time. A constant_z toolpath limited to a rest boundary could be wildly inaccurate.

Experiment, but most of all, have fun!

Regards,
Steven
_________________
Imagination is more important than knowledge -Einstein

PowerMILL :: RE: cycle times

Author: Wrecker1
Posted: Thu Jul 03, 2008 9:46 pm (GMT 0)
Topic Replies: 13

Of course you can. My email at work is predmond@victoriaproduction.co.uk