Questions on Nesting

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mkingaz
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Questions on Nesting

Post by mkingaz » Fri Nov 01, 2019 2:44 pm

As a new guy still learning a lot, I have a question on nesting parts. When I see other nesting a full sheet (some are amazing) do they keep the cut speed the same throughout the entire cut and are they cutting all of the parts continuously. I see many with large parts and a ton of smaller jobs and trying to understand how this cutting is done.

Thanks,

motoguy
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Re: Questions on Nesting

Post by motoguy » Fri Nov 01, 2019 11:32 pm

In sheetcam, I add each item as an individual "part" in sheetcam. Each "part" has multiple layers, and each layer may have different settings (cut speeds, rules, etc). That is when I add each part individually, and nest manually.

If I nest in my software (CorelDraw) using a plugin (eCut), it outputs everything as a single DXF file. Unless I break that file up manually in Sheetcam (ie, manually separating out parts again), the whole sheet is cut with the same setup/settings/rules.

So, the answer is...it depends.
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acourtjester
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Re: Questions on Nesting

Post by acourtjester » Sat Nov 02, 2019 8:54 am

Another thing to consider is if you are cutting a part with both inside and outside cuttings. You plan the the inside part first and then the outside, this helps as the part may drop out. If the outside is cut first and drops out then you cannot cut the inside part. If the planning is done in SheetCam some operations will be done first covering the whole sheet the finish the rest. By this I mean I have setup center punch makings for all the parts in a nesting of many parts. SheetCam will work all the center punches in first then start cutting the remaining parts. In this video you can see the center punches being marked and then I have a pause in the plans so I can change the amp sitting then finish the cutting of the parts.
https://drive.google.com/file/d/19JD2Tc ... sp=sharing
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beefy
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Re: Questions on Nesting

Post by beefy » Sat Nov 02, 2019 12:06 pm

Your question has me confused. What do you mean when you say you are trying to understand how this cutting is done. Cutting 2 or more parts is done the same as cutting one part.

Why do think it may be necessary to change cut speed simply because there's more than one part.

And what do you mean be "cutting continuously". Are you referring to chain cutting where the torch does not pierce for each peice but instead the leadout of the previous cut simply continues to the leadin of the next cut.
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motoguy
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Re: Questions on Nesting

Post by motoguy » Sat Nov 02, 2019 12:19 pm

beefy wrote:
Sat Nov 02, 2019 12:06 pm
Your question has me confused. What do you mean when you say you are trying to understand how this cutting is done. Cutting 2 or more parts is done the same as cutting one part.

Why do think it may be necessary to change cut speed simply because there's more than one part.
True, but different parts may have different requirements. Part 1 is a large (24") circle...cut at book speeds, THC active, all is good. Part 2 may be a small bracket, with 4 sharp corners, and 4 small (.2") holes. If you want those small holes to be round, you'll need to slow down your cut speed. Which means disabling THC as well.
beefy wrote:
Sat Nov 02, 2019 12:06 pm
And what do you mean be "cutting continuously". Are you referring to chain cutting where the torch does not pierce for each peice but instead the leadout of the previous cut simply continues to the leadin of the next cut.
I agree, his question is vague, but I can see some ways that it can go. Do you just start cutting vertically up and down the sheet, in a cut path? Or do you cut all inside contours first, then all outside contours (not recommended)? Or, do you cut each part individually, then move on to the next one (recommended)? Etc.

Some clarification of the question would be helpful. However, I see echoes of my experiences in it. Ie, the first time I changed from .part files defined in Sheetcam (multi-layers, multi-rules per part, etc), to exporting a "nested dxf" from Coreldraw...where an entire sheet of cuts is treated as 1 big layer.
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Re: Questions on Nesting

Post by beefy » Sat Nov 02, 2019 6:50 pm

Hi Motorguy,

the OP definitely needs to be a little more specific. Regarding the "how this cutting is done" question (very vague), and the changing cut speed question, I fully understand what to do if you have the differences in parts as you describe, but I just want to make sure I know exactly what the OP is asking for first. Sometimes I answer questions only to find out I wasn't answering the right question LOL.

I think half the problem for new guys is they are not sure what to ask. They have some idea in their head of what the want to achieve but don't know how to ask it in a specific way.
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Re: Questions on Nesting

Post by djreiswig » Sat Nov 02, 2019 10:16 pm

Even if you do answer the wrong question, I'm sure at some point in the future the information will be helpful to someone.
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beefy
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Re: Questions on Nesting

Post by beefy » Sun Nov 03, 2019 5:13 pm

djreiswig wrote:
Sat Nov 02, 2019 10:16 pm
Even if you do answer the wrong question, I'm sure at some point in the future the information will be helpful to someone.
Of course I could do that, but I choose not to. I have a lot to do outside of trying to help a little on forums and do not wish to double up on my time writing something up again when the first one was not the correct answer. Plus what I've found quite often is many I've helped aren't appreciative enough to say a simple thanks. Many times they don't even come back to the thread. If I wanted to give random information away to the masses I'd write a PDF and post it here.

If it's important to the OP he/she will be back to clarify the question.
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Re: Questions on Nesting

Post by djreiswig » Sun Nov 03, 2019 8:35 pm

I for one appreciate all the help you have provided.
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Re: Questions on Nesting

Post by acourtjester » Mon Nov 04, 2019 9:51 am

There have been many questions posted and many answers given. Many times, the OP just gets the answer and does not reply, this effect the validity of the answer. This presents a problem in that wither the answer was correct or the OP found an answer, or the answer help them to find a correct answer. Now this make it so any other member having that problem will need to post the question again. Where if the question was answered or a reply stating what the correction was. This is now available for other to find it with simply using the search function on the site. This is more helpful in a manor of time those having a problem then waiting for a member to read and then reply to their question.
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mkingaz
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Re: Questions on Nesting

Post by mkingaz » Mon Nov 04, 2019 11:01 am

Well you all offered several solutions and I realize my questions lacked some detail. As a brand new operator of a machine sometimes I simply don't know how to ask a questions because I don't have the experience. The main questions was cutting a full nested sheet with many different parts requiring different speeds, etc. I think the best answer I saw was that they are NOT always cut all at the same time with the same tool set. I can understand that, plus the options to add parts in Sheet Cam as a layered part (I think I'm explaining the correct). The answers to the post was helpful to me.

Thank you,

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acourtjester
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Re: Questions on Nesting

Post by acourtjester » Mon Nov 04, 2019 9:25 pm

I have found if you are cutting parts from a single sheet the cut speeds will not differ along with the other setting (amps, height, ect). In the video I attached I was not cutting all the way through the sheet to make center punches with 20 amps. Then a pause was in the G-code for me to return to 45 amps to cut through the metal and finish all the parts. Now if you do as some do they use code snippets to have the torch movement slow for corner cutting, this again is planed into the G-code. I find no change in speed for inside, outside and on the line cutting, this also is in the plan for the g-code to me created. Normally the cuts are made with the inside cuts first and then the outside last for each part. It may help to view some YouTube videos to see a table cutting parts to clear thing up. ASk questions but do include you table info and material info too.
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