CNC Chop Saw

Introduction

• An automated chop saw has the potential to save 60-75% of the cutting time required for all the dimensional lumber that is used to build a Seed Eco-Home.
• The biggest saving with a CNC Chop Saw is the time savings of measurement. Many times lumber is measured, and long lumber takes at least the amount of time to measure as it takes to walk from one end of the piece of lumber to the other. For a 16' piece of lumber, that is 4 seconds at a 3 mph walking speed. Add to this placement of tape (3 s), looking up the measurement (5s), marking (3 s) and then rolling the tape back up - (5 seconds) - this could easily be 15 seconds per marking. Moving the lumber into position takes another 5 seconds, and adjusting on the saw another 5 seconds, for a total prep time of 25 seconds for a single cut. The cut itself would take only about 2 seconds on a sharp chop saw. Then the lumber is placed on a finish cut pile, or another 10 seconds. Counting (inventory) can also take 5 sec as every so often the operator works through an inventory count. Total time to process 1 board: About 47 seconds.
• What is it?The CNC chop saw consists of an elongated table with rollers where the piece of lumber is placed on rollers, and the lumber is rolled on the rollers until the lumber hits a stop. The chop saw moves via CNC to the desired cut length, and all the operator has to do is turn on and lower the chop saw to cut the lumber. The processing time for one board eliminates the measuring, marking, moving, and most of the positioning. The estimated time is 5 seconds to place the board on the conveyor until it hits a stop, 2 seconds to cut, and 10 seconds to place it on a finish cut pile before being ready to start again.
• Ergonomics.Thus, we have 17 seconds vs. 47 seconds. This saves over 60% of the labor to do the pre-cutting - but also another important effect here is the improved ergonomics (mostly the roller) which reduces operator fatigue significantly. This means that an operator could maintain their rate of production for a longer time, as opposed to, say slowing down by 50% in the second half of a day, or 25% slower on average. Thus, the CNC saw would save approximately 70% of the time.
• For the automated route using a CNC Chop Saw - the prep time is reduced to placing the piece of lumber from the pile onto the rollers, which hits against a stop, as the saw moves automatically to the correct cutting length . All the operator needs to do is hold the lumber against the stop, and lower the chop saw after turning the chop saw on.
• The Seed Eco-Home has about 100 modules - or around 600 cuts. This means about 10 hours of cutting and marking. This time can be reduced to 3 hours.
• Process summary. The two versions of the overall process acting upon a stack of different lengths of dimensional lumber:

1. Manual Route: taking a pile of dimensional lumber, measuring, marking, placing lumber on work table, adjusting on saw, cutting, moving to finished pile
2. CNC Route: Placing lumber on cutting table, cutting, moving to finished pile

Used For

• Lumber Production

Basic Design

1. Long Working table surface (20') height is at a comfortable working height for the operator
2. Rollers where lumber is slid into place from the working pile. In this case, minimal space is needed, and a single operator could easily take the raw lumber from a pile and place it onto the rollers by themselves
3. End stop against which the lumber is placed, marking the 0 point of CNC system
4. CNC X axis like in Universal CNC Axis, to which a standard off-the-shelf Chop Saw is attached firmly
5. Back stops in addition to end stops, such as lumber placement involves one push against the back and end stops to locate (zero position) the lumber properly for cutting
6. Placement of chop saw in such a fashion that the rollers are not cut. Possibilities: sliding chop stops at the end of the lumber, no lower. Or, endstop moves together with chop saw so that the rollers never end up exactly below the blade.
7. Basic function is a simple chop, but angle cuts can also be made
8. Touchscreen which allows one to select the piece of lumber for cutting. Logic should be such that the program keeps track of inventory. Turnkey build scenario for a Seed Eco-Home would be completely programmed, where the program goes through cutting based on the workflow of a build event.

See Also

• Open Source Digital Fabrication Construction Set
• Universal Axis