Hollow Chisel Mortising System Opinions

[Hobbyman2]

I have used the mortiser attachment several times with good success , my results match reible's post . I picked up a set of off brand bits from the neighbor and they would not work do to the shaft size and the collar , I had a local machine shop ,make a collar to fit the bits and quill .

[rambo2981]

The mortising attachment arrived, and installation was straightforward. I spent some time sharpening the chisel with the supplied cone sharpener, and cleaned off the outside burr on all four sides with Japanese water stones. The initial results, however, were disappointing. For some reason, the bit cutter arc swings outside the square chisel lines. For mortises that mate with a piece that has shoulders, like a fixed tenon, these imperfections would be hidden. But for exposed mortises, like I need to cut, they’re unacceptable. I removed the bit and sighted the bottom as I turned the bit slowly by hand, and the cutter does swing slightly outside the chisel line. I’ll call Shopsmith support on Monday and talk to them.

[reible]

Did you use the dime trick to adjust the cutter to chisel spacing? Either too much or too little space can be a problem.

Ed

[JPG]

How does the 'spacing' affect the OD?

Methinks a QA problem.

[rambo2981]

How does the 'spacing' affect the OD?

Methinks a QA problem.

It doesn’t.

[JPG]

How does the 'spacing' affect the OD?

Methinks a QA problem.

It doesn’t.

Good luck Monday!

[rambo2981]

I put a caliper on the chisel and the bit. Chisel is .374 and the bit is .364, so it’s not the end of the bit being oversized. I laid a straight 1/4” steel rod on the shaft of the bit as it spun and saw no movement on the shaft. Then, I rolled the bit on a flat cast iron table with the cutting end hanging over the table end, and there a wobble in the fluted portion of the bit which wouldn’t show up with my steel rod test, because it’s further down the shaft of the bit. At this point I believe the 3/8” chisel bit is defective. I’ll try the other bits.