How to Use the Bar Cutting Layout Optimizer
Angle, channel and tube arrive as mill lengths, typically 20 ft bar stock, and several different part lengths come out of each stick. Which lengths get grouped together decides whether a job takes eight sticks or ten, and the leftover drop usually goes straight to the scrap bin, so the layout is a direct cost item.
Enter up to three part lengths with quantities, the stock length in inches and the blade kerf. The solver sorts pieces longest first and places each one into the first stick that still has room, which is the first fit decreasing method. One kerf is deducted for every piece cut, so drop lengths come out slightly conservative, and the pattern table lists each distinct combination, how many sticks use it and what drop is left over.
The theoretical minimum is total part length plus all kerf losses divided by the stock length. When the solved count equals that number there is nothing left to recover. If it runs one or two sticks higher, trimming a part length slightly or ordering a different mill length often closes the gap. Setting a minimum length worth keeping in the remnant rack also helps, and any change to structural member lengths should go back through drawing review before it is used.
Frequently Asked Questions
By first fit decreasing, which takes the longest piece first and drops it into the first stick with room left. It follows the same order a fabricator uses by hand and runs instantly even for large quantities.
A band saw usually takes about 0.09 in, a cold saw 0.125 to 0.16 in, and plasma or oxy-fuel 0.2 in or more. The model deducts one kerf for every piece cut, so reported drop lengths are slightly conservative.
No. Solving one dimensional cutting stock exactly is expensive, so first fit decreasing returns a good approximation. The theoretical minimum is shown alongside it, and when the two match there is nothing left to gain.