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Cutting a step on the outside of a part.

Posted: Mon Jul 30, 2018 9:20 am
by sterob
I want to cut out a 'backing plate' for a Trailer Socket and i want the backing plate to be recessed into the Socket, ie I want to machine a small 'step' around the outside of the part.
Anybody know how to do this?
I've tried to create a tool path to cut the step THEN cut the part out...no good. Get an error....can't remember what error now...sorry.
I tried to 'pocket' the area I want to step, but that didn't work.....
I tried to Cut the pocket to a larger size, but that didn't work.....

If I select both outlines, all I get is a pocket over the whole job....not the step I only want.
Software does not seem smart enough to know I on't want the edge cut.

Am I missing something? Is there an easy way to do this? I can't imagine it would be a Cut3D feature only?

Steve

Re: Cutting a step on the outside of a part.

Posted: Mon Jul 30, 2018 10:41 am
by AlanAndrews
It is always better if you can provide an image or file of what you are trying to machine.

This will always help to understand your requirements better and provide informed suggestions/recommendations.

I'm not conversant with the limitations of Cut2D, as I'm using Vcarve 9 Pro. In VCarve 9 Pro, this sounds like a simple 2 sided design.

In which case, can you not simply turn the part over and reverse your design? You'll need to build in some reference points in order to get everything aligned.

And if all you need is a recess then does not need to be and exact profile cut....merely a cut that will remove an area of material in order to give you the recessed fit you require.

Re: Cutting a step on the outside of a part.

Posted: Mon Jul 30, 2018 12:22 pm
by Adrian
Sounds like you just need a simple pocket. Make sure that the vectors you use to define the inside and outside of the pocket are closed vectors and that you have both selected when creating the pocket toolpath.

Re: Cutting a step on the outside of a part.

Posted: Mon Jul 30, 2018 12:44 pm
by sterob
Hi Allan,
Thanks for your comments.
Sorry, I was at work and did not have access to any of the files. I was aware how hard it would be to explain....lol

I've had another look, and I *think* the problem may be an Open Vector. See pic.
When I select the inner edge, the bottom section has a the dark line still visible.

I think this is causing that edge to be ignored. I ahve not been able to fix it yet. Still looking at it.

Steve

Re: Cutting a step on the outside of a part.

Posted: Mon Jul 30, 2018 12:58 pm
by sterob
The dark line above was caused by a double line....somehow I drew two lines on top of each other....doh.

Cut2D will let me cut the 'step' on the outside of the inner line but it won't let be do final full depth cut to release the job.
I get this error:
Steve

Re: Cutting a step on the outside of a part.

Posted: Mon Jul 30, 2018 1:13 pm
by bravesoul
Generally that means that you have selected a tool that is too large for the job.

Re: Cutting a step on the outside of a part.

Posted: Mon Jul 30, 2018 1:52 pm
by sterob
I though that as well. I then added a larger boundary to make sure there was enough room for the tool.
That was ok, but I still can't do the final cut out toolpath. It seems to think there isn't enough room when there is.


I'm stumped for now.....

Steve

Re: Cutting a step on the outside of a part.

Posted: Mon Jul 30, 2018 3:40 pm
by Adrian
What toolpath are you using for the cut out? The usual is to use a profile toolpath set to be Outside the vector.

Attaching the actual file is always best with issues like that as it's hard to tell much from a screenshot.

Re: Cutting a step on the outside of a part.

Posted: Tue Jul 31, 2018 4:35 am
by sterob
Adrian wrote:What toolpath are you using for the cut out? The usual is to use a profile toolpath set to be Outside the vector.

Attaching the actual file is always best with issues like that as it's hard to tell much from a screenshot.
I have tried a Profile tool path. I tired to use a 6mm tool so the result produced a wider 'step' so when I cut it out, it cut the step to the correct size...
I tried a Pocket tool path( correct size) AND over size ( to make room for the tool )

It must have something to do with the changing widths of the 'step' as a simple circular object with a step is no problem ( I tested it. )
Trailer Adapter Back Plate FINAL.crv
(164.5 KiB) Downloaded 200 times

Re: Cutting a step on the outside of a part.

Posted: Tue Jul 31, 2018 7:44 am
by LittleGreyMan
The problematical toolpath does not seem included in your file, so it's hard to tell what's going wrong.

Is it this that you want to achieve?
Backing plate.jpg

Re: Cutting a step on the outside of a part.

Posted: Tue Jul 31, 2018 8:07 am
by Adrian
The outside vector is open which will probably be the root of your problems. If you look at the bottom of the right hand vertical section the issue is there. There is a short span that overlaps rather than joining.

Re: Cutting a step on the outside of a part.

Posted: Tue Jul 31, 2018 8:20 am
by sterob
LittleGreyMan wrote:The problematical toolpath does not seem included in your file, so it's hard to tell what's going wrong.

Is it this that you want to achieve?
Backing plate.jpg

Thanks Adrian,
I couldn't complete the last two tool paths due to the error.
Its almost right. I want the outside edge to be stepped down.

I will see if I can find the overlap you mentioned.
Thanks

Re: Cutting a step on the outside of a part.

Posted: Tue Jul 31, 2018 8:33 am
by sterob
I found the problem you mentioned and fixed it. There was a short extra line that I couldn't see. Thank you.
I noticed the difference in the dotted lines at that point before, but it didn't register as a problem.

Thanks for your help guys! :D
Steve

Re: Cutting a step on the outside of a part.

Posted: Tue Jul 31, 2018 11:17 am
by LittleGreyMan
Adrian wrote:The outside vector is open which will probably be the root of your problems.
I didn't noticed that. As I quickly selected the outside vector and run a profile cut with a 6mm mill selected by error, the toolpath was calculated without any warning and the part was totally cut in the simulation. But looking closely at the toolpath, it is not closed in the overlap region. The material is totally cut because of the sufficient tool diameter.

With a 3mm mill, I get the same error.

I will report it as a bug.

Aspire V9 demo

Re: Cutting a step on the outside of a part.

Posted: Tue Jul 31, 2018 12:33 pm
by mtylerfl
This is not a bug. The issue is the vector itself. The problem area is easily found by using the Vector Validator Tool. It's up to the user to make the correction after that. (see screenshot)