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We're setting up for a new cnc. I've been looking at what size material to use and it's a bit of a 2-side coin.
I optimize for all kinds of sizes, but our distributor carries all sizes of the thicknesses we typically cut. Our bread and butter is 4x8, but 5x9 or 10-12 ft stock will also fit on our table to nest with. The handling and storage drive the stock choice, unless we need certain sizes. I will nest those parts with others to get +/- 88% yield or better. Nesting on 5x9 generally nets higher yield, but at the cost of convenience for storage and handling. I'll nest on those bigger sheets if there is a whole run of cabs that are deeper, but if only a few parts are wide then the rest of the parts fill in.
All this is moot if you are doing wood veneers that are generally available in 4x8 ubiquitously, but are special for the other sizes. I'll often do trial nests before ordering material so there are no surprises, but again we do mostly melamine, so its about convenience mostly, not yield.
I think the best initial move would be to take a look at nesting your most common components in the available sheets.After looking at component yield and sheet cost a few pointers ought to emerge.Obviously veneer faced panels will have a reduced yield because you can't deviate very far from the grain orientation.If you don't currently have nesting software,maybe the trial version of Vcarve would be worth an hour or two of your time.
Thanks for the responses. It has helped me think it through.
Material is generally the least of your costs on a CNC.
Whatever you save on material you have spent on the time it takes to trial nest on different sizes of material.
Use the largest material you can regularly buy. Load/unload and tool change time doesn't care if you are cutting 4X8 or 5X10.
And resist the temptation to try to use offcuts unless they are 3/4 of a sheet or larger. The offcuts you use are just replaced by the ones you create.
% of yield is not a number to watch, if one pattern takes 4 sheets and is faster than a more complex patter than takes 4 sheets with higher yield, unless the drop is high dollar I think its more important to focus on number of sheets consumed, not yield.
We use 5/8" almost exclusively. Its very rare that we need a 5' sheet.
For the fridge gables your concerned with being 26 or 30" wide, there are usually other small parts that can fill the rest of the sheet.
If not, we just chuck the waste and just consider it part of the jobs material cost.
The 5' wide material usually carries a bit of a premium and the sqft price, so the cost difference is usually only a few bucks on a kitchen.
We have a 5x12 machine. It’s pretty ugly when 5x8 materials come in Then there is 5x12 1 1/8” pb. The bigger stuff wears you out even with a lift
Make sure you keep in mind a quality core
When going to nesting, my big mistake at first was thinking like I did before. When I changed the way I looked at things, we solved a lot of problems. Multiple materials are a huge waste. We were building cabs with 3/4” sides, 1/4” backs with 1/2” nailers. Yield on 1/4” is horrible and it doesn’t cost 1/3 less than 3/4, so in the end it cost more than 3/4” when you throw out 1/3 of a sheet, not to mention storing it and handling. We went to all 3/4”, sides, tops backs, use stretchers on top. When we did that yield went to 99% on every sheet but the last one as everything fits in. In your situation you won’t nest 2 fridge verticals on a sheet, you will nest a whole job and might have a fridge panel and 12 small parts on that sheet. Don’t think like a table saw and line bore, think like a jigsaw puzzle. Don’t think this is how we build cabinets, think how can we build efficient cabinets.
Then the issue is how to get to building as fast as you can.
I would always cut the nest backwards starting with the second last sheet. You get more parts faster and are more likely to get all the parts for any given cabinet sooner. I cut the last sheet last because it is not likely to be full and you should have room to add a damaged part if you need to.
We have a rolling carts with slots in them. Number the slots to match the cabinet numbers. Off the machine and into the slots. Band before or after, doesn't matter.
Do it right and you can be building the first cabinet of the job while the CNC is still cutting the rest of them.
In cv you can adjust how it nests best yield with no order will give you parts for cabinet #1 and 100 in first sheet, we set it to overlap 5-10 cabinets. That gives us best yield and keeps them close enough that we can start building
The seven last words of a business are:
"We've never done it that way before"
Post #13 has the ring of experience about it.Is there anybody who has not been in a situation where this kind of thing surfaced?
thanks for the responses guys/gals