Blade cuts a curve when ripping a wedge V

**Dengue** · 1st September 2021, 11:36 PM

My son-in-law makes cricket bats. They come in two parts, the blade and the handle. He cuts the V in the blade, and then cuts the handle on the bandsaw into a wedge shape to fit the V in the handle. Needs to be an exact fit, ready for gluing.

When purchased, the handles are a rough cut round piece of timber. like a 1.5" diameter dowel.

When cutting one end of the handle into a wedge V, it is held in a jig, and the jig slides forward for the first cut on the right side of the wedge, and with a spacer, the jig is rotated 5 degrees and the other side of the wedge is cut.

The problem is the the cut on one side is perfectly straight, when measured with a straight edge and a light underneath, but the other side of the V does not cut straight. It is rather curved, as shown exaggerated in the attached hand sketch.

He also uses this jig to trim the side of the wedge, running it up and down on one side of the blade to get the cut surface fairly smooth, ready for gluing in the V in the handle

He uses a 3/4" blade, about 4 tpi, and it has not had much use since new, because of this problem.

Can anyone please advise the likely cause of this curved cut, and how to solve this problem?

Bat handle cut.jpg 20210831_182427 Large.jpg

**riverbuilder** · 2nd September 2021, 07:44 AM

Must be the blade, try a different band.

**NCArcher** · 2nd September 2021, 10:04 AM

Drive a wedge against the cut side so it can't deflect away from the blade. The first cut is straight because there is enough material there to support the cut and stop it from deflecting.

**Mobyturns** · 2nd September 2021, 10:43 AM

Originally Posted by NCArcher

Drive a wedge against the cut side so it can't deflect away from the blade. The first cut is straight because there is enough material there to support the cut and stop it from deflecting.

I agree, the handle is flexible, so when the first cut is made there is a reasonable amount of material supporting the cut. However on the second cut there is minimal support on the "keeper" side of the cut, which allows the handle to deflect in the cut. When ripping "thin" or "composite" materials the blade will often take the path of least resistance, which may not always be the desired path.

Same can occur when commencing a cut with a bandsaw depending on the grain orientation within the blank - i.e. cross cut, rift, plain sawn, quarter sawn etc.

Solution - simply make a two stage sled for cut 1 and cut 2 which fully supports the cut to prevent both deflection and any potential rotation. Also a slow feed on commencing the cut will help alleviate deflection issues. Other thing to look at - saw plate thickness - thin kerf rip blades can wander badly in some scenarios.

**labr@** · 8th September 2021, 07:35 PM

How did you get on with this Dengy - is it fixed and if so what worked?

**Dengue** · 8th September 2021, 11:24 PM

hi Bob, a new 1/2" 3tpi bimetal blade arrived today from NSW. I have just sent it over to the son-in-law, who will probably fit it on the weekend. I have also passed on the tip about using a wedge to keep the workpiece in position while it is being cut.
Will keep you informed.

**Mobyturns** · 9th September 2021, 08:27 AM

Another thing to check will be blade tension ....

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