Mortiser problem

[Larry R. Tysinger]

I'm new to mortising and experienced a problem with a new Powermatic model 701 bench top mortiser.

When doing my first attempt the chisel and bit got extremly hot in just a few seconds. I thought may be I did not have the bit and chisel installed properly. I read instructions and tried again with the same results.

I was working with birch using 1/2 chisel and bit. I need a 1 1/4 deep mortise.

Any sugestions would be appreciated.

 

[Travis Porter]

I would suggest you have the drill bit too deep / too far into the chisel. You need a big enough gap that the bit can freely discharge the chips/waste up the chisel. I learned this the hard way with 1/4" chisels. I had left a gap, but a small one, whereas I should have left around 1/16 to an 1/8". I broke three bits.... For that big of a bit, I would probably go 3/16 to a 1/4". Basically, the bit is at the bottom of the chisel points.

Hope that helps.

 

[romanf]

I can't remember where I read or heard it, but I was told to use a dime as the space between the chisel and the bit. Easy enough to remember and is a good starting point. Depending on the wood and how the wood actually chips out, you may need to increase the space a bit to accomadate larger particles of wood. Be very careful to allow enough space, as you can lose the temper on the chisel if it gets too hot. It will turn blue near the edge and not hold an edge very well after that.

 

[Sully]

Beeswax can also help on the chisel. Plunge a little, touch beeswax to the chisel. Repeat.

 

[BrianGeib]

Larry - I picked that same model on Friday at Woodcraft. Have not had any problems using oak. One question would be - did you insert the top "spacer" when you were install the bit/mortiser? There are two spacers which swing out from the mortiser to provide proper spacing. After inserting the bit you swing the spacer out of the way.

 

[Travis Porter]

Check out this article from Tom Hintz, one of our members. It has pictures so that should help.

http://www.newwoodworker.com/setupmort.html