Arranging cuts on sheet goods

[sawkerf]

How do you arrange your parts to be cut on sheet goods? I'll pick up my SB on 1 Oct and I've been wondering about this. Is there some step in the software where you place parts, or is it automatic? Oh, and what is nesting or nested based manufacturing? Thanks, Kip

[beacon14]

Kip,

That's a very good question, one that many cabinet shops will be asking now that the PRTAlpha can offer the speeds required to handle nested-based manufacturing, which is simply the technique of arranging parts to fit optimally on full sheets of material, then machining and cutting the full sheets on one machine. (Much larger operations use point-to-point machining, where stacks of material are cut out on giant beam saws, then individual parts are sent to various machines to have secondary operations like holes, dados, arches, etc. milled).

Unfortunately, the software that comes with the ShopBot will not automatically arrange your parts on the sheet. (It will create the toolpaths once you have manually arranged the parts, or imported nested sheets from another program). If you use CabinetVision, Cabnetware, or some of the other cabinet-specific packages, many of them offer nesting software as an option, and most of the better-known ones will output ShopBot code directly. For now, your options will be to manually nest your parts in PartWizard or another CAD program, or use another (probably more expensive) software program that supports nesting.

I think Gordon and the rest of the ShopBot team will be working on this issue, as it represents a potentially huge market for them. Let us know what you end up doing.

David B.

[srwtlc]

Heres's a great 'Virtual Tool' possibility. Key in your part sizes (might be kind of tough to get arches, dadoes, or toe kick notches) and maybe a option to do shelf pin holes at the same time.

Scott

[bill.young]

Hey Scott,

The "Drill Press" and "Forney Fluter" started out as just a couple of the bits and pieces that will eventually become a cabinet designer tool, loosely based on the 32mm cabinet system. My guess is that it'll end up being a Project Wizard project, though, because of the complexity...too much for a Virtual Tool.

The vision is that you'll be able to lay out a set of custom cabinets and get the cutting files for the parts for those cabinets for a modest fee. Unfortunately it just one project among many, so don't ask when it will happen! Maybe someone at the Programming camp will want to work on it!


Bill

[richards]

Kip,

This may be a little off-topic to your question about nesting, but it is an effective method that I use for cabinet parts.

I use AutoCad Lite to design all parts. After the parts are designed, I align them horizontally and vertically so that as few straight cuts as possible are necessary. (Right now the parts are spaced 0.460 inches apart, based on the use of a 3/8-inch cutter doing a rough cut and a clean-up cut.) After making a layer for each cutter, 1 add two more layers, one is for the rip cuts (a single line in the center of each 0.460 wide X-Axis cut) and the other is for the cross-cuts (again, a single line down the center of each 0.460 wide Y-Axis cut)

Assuming the use of 0.70 inch baltic birch plywood, (18mm), in PartWizard I create a tool path (machine along vectors) for the rip and cross-cuts at 0.60 inch deep @ 3-ips (Porter Cable router, single-flute bit, 19,000 rpm). Next I create a perimeter tool path for each part at 0.660 inch deep @ 8-ips (2-flute spiral bit, 19,000 rpm.)

The rip/cross-cut tool path cleans out the majority of the waste, but leaves a fairly rough cut. The profile cut cleans up the tool path to an almost perfect finish since the spiral cutter only needs to take about 0.040 of an inch. The last cut also leaves a paper thin piece of material to hold vacuum with the Fein vacuum that I use.

(Letting PartWizard make two passes, one 0.030 inch oversize and one at exact size also works, but there is a lot of unnecessary cutting taking place.)

[sawkerf]

Wow, thanks...I think. Hopefully this Shopbotese will all begin to make sense after I get set up! Just 1 more week till I pick it up. But thanks for the input, Ha Ha. Get it? ...input. Ok, lame newby humor. Sorry, Kip

[erik_f]

Nesting is when the computer program will move and rotate parts to find the best fit of the parts onto a given sized piece of stock. I suppose it would be nice to have it (I don't) but I have done just fine without it. Have you decided on what software you are going to use? This will have a big impact on how fast you will be able to get from comuter to cutting. When I started out I had no experiance at all with CNC or CAD/CAM software. I bought a set of software...that got me by...but have invested in some new software a couple months ago...and am much much happier now. Most of all...be prepared if you are as unexperianced as I was, for some gnashing of teeth and moments of bewilderment...but enventually things fall into place and then you will be able to use your shop bot like you use a table saw.

Erik

[sawkerf]

I will be using KCDw, which will export the DXF files. I will probably purchase an optimizer soon. There are several links listed on the KCDw website that offer affordable solutions.
Is nesting and optimizing the same thing, it seems it is but I don't know enough about all thes terms to be sure.

[richards]

Nesting and optimizing are two different things (in most cases).

Nesting usually relates to having parts laid out for the most parts per sheet of material.

Optimizing usually relates to having the most efficient tool path within a part. For instance, in AutoCad Lite, without optimizing, a tool path would be created in the sequence that you drew the lines. After optimizing, the tool path would follow the most efficient path.

PartWizard does a fairly good job of first-run optimizing. When I'm just running a few sheets of the same parts layout, I usually leave the toolpaths created by PartWizard alone. However, if I'm running a set of parts that I'll repeatedly use, I spend the time (minutes to hours) necessary to follow the most efficient path.

Since I don't use a nesting program, I can only speculate that a good nesting program would also include a good optimizer.

Mike