Cutting out multiple parts from one piece of stock

[CarlofET]

Hello all -

I've hit a bit of a road block and wondered if the folks here could help me.

I have a brand new DIY CNC machine that has a cutting table of about 30"x108". We want to be able to put one piece of stock on the table and cut out as many pieces as will fit in that stock, while preferably having one cut from the router share edges from two different parts.

We would like to leave the pieces connected with little tabs to maintain the one-ness of the stock such that the parts can be either broken out when finished or cut out easily with a knife.

The parts are designed in Solidworks. So far I have tried making new parts in solidworks that are nests of the parts we want with the little tabs included, but I'm having a heck of a time getting mastercam to generate usable code. If I leave a 1/4" gap between parts in solidworks and then tell mastercam I'm using a 1/4" bit, it doesn't seem to want to make the cut. It's starting to make me a little nuts, wondering if I should try some other software or what. Hoping someone here has some insight on the subject.

Thanks in advance!

[jhowelb]

http://www.vectric.com/WebSite/Vectr...ew_nesting.htm

[jsheerin]

I usually space my parts slightly larger than what the cutter size is. Otherwise I get the same problem as you do where my cam program (visual mill) won't want to cut there. If I want tabs between my parts, I either have to do what it sounds like you're doing (draw the tabs in by hand) or space the parts farther apart so my cam software will put them in and they won't get cut when cutting the adjacent part.

[Phife]

There are several CAM software packages available that do all the nesting and generate the code for you. Its very quick and simple to use.

I am using Vcarve pro to cut out my nested sheet stock. Vectors are drawn in sketchup and then exported to Vcarve. I then use vcarves join vector feature to fix up the broken lines and use its nesting feature to lay out the parts.

Doesnt mastercam have something similar?

[ger21]

A lot of the high end woodworking nesting programs can do that, but they run several thousand dollars.

[louieatienza]

You think it would work if you spec'd the cutter a couple thous smaller than it really is?

[CarlofET]

Thanks for the info everybody. I spent the better part of today battling mastercam and came up with a solution.

The problem I was having, as I mentioned, was that mastercam wouldn't mill out a 1/4" gap with a bit that's exactly the same size. First I re-arranged the assembly so that the parts were spaced 0.3" apart, and I was able to get the profiles worked out, but it was still ignoring the tabs I added. Further, it was then making two passes down each shared cut, which I wasn't very crazy about. Eventually I figured out a way to manually select each edge for the bit to follow and was able to move the pieces back to the 1/4" gap and have it follow my tabs. The process is a little time-consuming, but shouldn't be bad when considering the time I'll save on the machine while being able to share cuts between parts.

Originally Posted by jhowelb http://www.vectric.com/WebSite/Vectr...ew_nesting.htm

Originally Posted by Phife There are several CAM software packages available that do all the nesting and generate the code for you. Its very quick and simple to use. I am using Vcarve pro to cut out my nested sheet stock. Vectors are drawn in sketchup and then exported to Vcarve. I then use vcarves join vector feature to fix up the broken lines and use its nesting feature to lay out the parts. Doesnt mastercam have something similar?

Coming up with the actual nest layout isn't so important for me -- the parts we're cutting are pretty regular sized and so it's usually just a grid. Mastercam does the nesting thing too but I found it much to annoying and not all that efficient to use.

Originally Posted by jsheerin I usually space my parts slightly larger than what the cutter size is. Otherwise I get the same problem as you do where my cam program (visual mill) won't want to cut there. If I want tabs between my parts, I either have to do what it sounds like you're doing (draw the tabs in by hand) or space the parts farther apart so my cam software will put them in and they won't get cut when cutting the adjacent part.

Originally Posted by louieatienza You think it would work if you spec'd the cutter a couple thous smaller than it really is?

I first went down this direction but was unhappy with not being able to share cuts.

Originally Posted by ger21 A lot of the high end woodworking nesting programs can do that, but they run several thousand dollars.

Out of curiosity, which ones are they? This is for a business so if there's a better software package that could make this job a lot easier, it would be worth the money at some point.

[ger21]

Are you using MasterCAM router? It does common edge nesting. Also check out Cadcode's nesting package. Others are integrated into cabinet packages, which makes the cost prohibitive.

Not sure if you can use common edge nesting as well as tabs, though. I use alphacam, and have found that it's tabs don't play nice with nesting, but we have a slightly older version.

[CarlofET]

Originally Posted by ger21 Are you using MasterCAM router? It does common edge nesting. Also check out Cadcode's nesting package. Others are integrated into cabinet packages, which makes the cost prohibitive. Not sure if you can use common edge nesting as well as tabs, though. I use alphacam, and have found that it's tabs don't play nice with nesting, but we have a slightly older version.

Yes, and I didn't see any option for that when I tried it. I'll keep those in mind, though so far things are looking OK for me. Once we get programs written I don't anticipate having to do a lot of new stuff, which is why I'm not all that worried about having the computer do the nesting. Thanks again.