What bugs you the most in SheetCam?

[DenkBrettl]

The thing that I find most inconvienient so far is that one can not easily combine path rules.

Hmm, interesting. I expected most people would create a few standard rules that cover the majority of applications. Why do you need to mix and match rules that much?

I mean, maybe I'm holding it wrong. Maybe you're right and in the end I should have a few rules that cover all my needs. I'm only beginning with plasma cutting and I guess I should rather create rules like "Material from 8mm to 12mm" and then throw in there things like "On Arc smaller than 30mm go at 60%" and leave them in there regardless whether there are Arcs in the drawing or not. Same probably for holes.

[SeanP]

I'm curious - why do you need to break up the drawing if you nested it in Corel?

For me when using nesting software to create the complete sheet as a dxf, I have a set of rules that work well on holes that don't work with the outer cut, likes of base plates I squeeze them in so tight I don't even use a leadin/out on the outer cut.
And likes of a part with a sharp corner I usually use a tangent leadin/out to run straight on and off the outer cut, quite often with a slowdown on the last 3-4mm to catch the tag as it crosses the leadin, but then a part with a radius corner or a round part I tend to use a arc leadin/out.

Trying to have 2 operations - one for the holes and one for the outside cut on a full nested sheet doesn't work well for me as it's no use cutting all the holes on the sheet and then all the outside cut's, so what I usually do is:

Put all holes on the nested sheet drawing onto new layer, create a operation for holes and another for the outside cut, then break apart the drawing so each part now has it's holes and outside cuts setup, then I need to go over each part and check/re-position the leadins, holes are fine slots quite often I move those to be central, all that works fairly well and usually better than trying to figure it out manually in sheetcam especially over a few sheets with quite a few different parts.
It would be a big help if you could position the leadins before breaking apart and then once broken apart they kept that position.

[David_Lelen01]

It would be a big help if you could position the leadins before breaking apart and then once broken apart they kept that position.

I second that.

And i reinforce the issue i have brought up earlier about the start point placement not working well and ignoring the "start point clearance" setting. The picture below is of a manual nest imported into sheetcam as a single part, using one operation. This is the default start point placement. Two practically intersect and several others are very close to other parts even though my "start point clearance" is set to 200%. Actually i just realized where the issue might be here... the start point clearance actually reads "start point tool clearance"... I'm guessing now that this is not dependent on the leadin length as i assumed it would be, but rather the diameter/radius of the kerf/tool.

Capture.PNG (150.94 KiB) Viewed 594966 times

[Les Newell]

Yes, the clearance is relative to the tool diameter/kerf width. If I remember correctly it also does not check clearance between leadins. The problem with doing that is that you can end up stuck in a loop. If you move one lead in to clear another, that could affect other leadins. You end up with cascading moves affecting each other making it very difficult for SheetCam to come up with an answer.

[sheetcnc]

Bug: any block in a DXF which is mirrored, gets mis-positioned by sheetcam. So any mirrored block in my drawings must be exploded before I can import the dxf into sheetcam. (My CAD implements 2D mirroring by rotating the block 180 about Y and scaling it minus-1* in Z.)

Feature request please: to group multiple operations (usually all with the same tool) into one selectable single item. My typical workflow involves a drawing with fifty+ layers, each layer being one operation. Typically these 50 operations are distributed across half a dozen tool changes. (E.g. layers might be 3mm2flute-pocket-2mm, 3mm2-flute-pocket-10mm, 3mm2flute-cut-thru-inside, 6mm1flute-pocket-20mm... etc) So for every iteration of my drawing, when I re-import into sheetcam, I have to select half-a-dozen sets of operations - each set containing many operations for one tool - and PP each set out into an ngc file for that tool. Easy to make a mistake. A "permanently-group-these-operations" function would make it so much less risky.

*Yes, even for 2D drawings, a minus-1 Z scaling is applied. If I remove the scaling (but leaving the 180 rotation) then the block is still mis-positioned. Either way, the typical result is that the block is shown by sheetcam at its un-mirrored position. I've tried scaling the item -1 in X instead... but my CAD just converts that to a 180-in-Y with a minus-1-in-Z, so I can't test if that would work for sheetcam. (My CAD is TurboCAD.)

[Les Newell]

Could you let me have one of these problem drawings so I can run some tests.

[sheetcnc]

Zipped here:

The .dxf
TurboCad's DXF settings (tho' I've tried all DXF options and the problem stays the same)
How it looks in TurboCAD
How it looks imported into SheetCAM
The .job

Have fun!

Cheers,
Ian.

[Les Newell]

Hi Ian,

I just tried opening your dxf with 5 different cad packages. 4 agreed with SheetCam. One agreed with Turbocad.

The question is - which is right?

Unfortunately this is a common problem with dxf. When Autocad released the dxf specs their docs were pretty weak and they haven't really improved over the years. As a result pretty much every cad package interprets the docs differently. Text is so bad I don't even bother trying to support it.

[Les Newell]

After looking at what Turbocad is doing and consulting the documentation further I think that although what they are doing is a bit odd, it is technically correct. The change will be in the next release.

[sheetcnc]

Thanks Les. It's not the only issue I get with DXFs and TurboCAD. But it is the one that's nearly impossible to work around. Scaling is another 'feature'... so many programs (including TC) will load a DXF and not recognise it as metric. Resulting in houses that are five thousand inches tall, or little parts like control knobs being 25" in diameter. Guess it being Merican is why the assumption that everything is in inches

[Les Newell]

Dxf files don't specify units, which as you say can cause all sorts of scaling issues.

[sheetcnc]

Re this bug-ette: viewtopic.php?f=2&t=8392&hilit=ramp

Reckon the fix might be in the next release, too? Pretty please?

[Les Newell]

Yup, It should be up on the website now.

[sheetcnc]

Hate to be the bearer of bad news, but SheetCAM is asking me to report a bug. Appears to be related to "Occasional incorrect tool paths when ramping an open contour". And the reflected-blocks thing seems to be still there.

I've upgraded to 6.9.15 and rebooted Windows for good measure.

"Occasional incorrect tool paths when ramping an open contour": it seems subtly different now. The return ramps are being cut away, but any intermediate-depth [i]flat[/i]cut isn't being completed. For example, I've made a cut 27mm deep, with 9mm passes. So there should be flat-bottom cuts at 9mm and 18mm. The 9mm one seems to be missing and the 18mm is only part-cut. That leaves ~20mm of material to be cleared during one of the ramp moves.

"DXF not reflecting blocks correctly when a negative Z scale is used": sadly doesn't appear much changed. In a previous version (6.1.45) I experimented with setting the Z-scaling to +1 for mirrored (actually in TurboCAD [i]rotated-180-about-Y-axis[/i]) blocks. But it made no difference to SheetCAM. So I wonder if the -1 Z scaling isn't the direct cause of the problem?

6.1.45 is the latest version I'm aware of without the "Occasional incorrect tool paths when ramping an open contour" issue which is quite important in my drawings, so I'll use that for now.

Cheers,
Ian.

[Les Newell]

Hmm, looks like it's Z extrusion, not Z scale. OK I'll fix it in the next release.