What’s the woodworking bottom clearing knife?
Woodworking bottom clearing knife can be used for slotting, milling plane, and can also be used for the tenon. The blade of the bottom cleaning knife is relatively wide, which is suitable for the fine finishing of a large area. The bottom cleaning knife is mainly used for processing shallow grooves, and the groove depth is lower than the thickness of the plate. Therefore, the bottom cleaning knife has higher requirements for the surface finish of the bottom of the groove than the double-edged straight knife. The bottom surface of the shallow groove is required to be smooth and free of burrs, eliminating the process of reprocessing the plate and improving the processing and production efficiency. The size of the bottom cleaning knife can be selected according to the groove width and depth of the plate to be processed.
The blade of the bottom cleaning knife protrudes a little downwards, has a certain undercutting ability, and is a little more convenient for milling closed grooves. But because the down-cutting ability is not very strong, milling deep grooves often needs to be milled several times. I would rather use ordinary straight cutters + electric drills. But the bottom cleaning knife has another use: it can be used to level wood with a simple jig, partially replacing the function of an electric planer. If you don’t have an electric planer or the electric planer is not good enough, you can try to use a bottom knife, which is a bit tiring and has to be milled many times.
What’s the straight cutters?
Straight cutters can be used for milling grooves of various widths, milling tenons and mortises, etc. It can also be used for straight tenon connection, finger jointing, or panel jointing with simple fixtures. There are many sizes of straight knives, the most commonly used are 1/4 inch and 1/2 inch straight knives. If you want to mill a slot wider than 1/2 inch, you can mill it twice, and the slot between 1/4 inch-1/2 inch can be milled twice with a 1/4 inch straight cutter.
The straight knife is mainly used for grooving or tongue-and-groove, the bottom cleaning knife is mainly used for repairing the bottom of the groove, and the trimming knife is mainly for repairing the edge of the workpiece.
Differences between straight knife and bottom clearing knife:
Simply put, it is a bottom job and a side job. Undercutting knives generally have a blade length lower than the thickness of the plate (shallow groove) to try the bottom and the measuring surface to produce good results. Generally speaking, the straight knife only has the cutting function of the lower knife, which means that the side processing effect is good, the bottom processing is not good, and the bottom processing cannot even be done.