Mortising Chisels getting stuck


Old 12-07-99, 11:15 PM
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I have a mortising attachment for my drill press. The problem I am having is that when I go to make the 1st plunge, the chisel gets stuck in the workpiece. I have tried coating the chisel with wax and moving the drill further below the chisel to try & get rid of some of the wood before the chisel starts, but haven't had any luck. Any help on how to cure this problem would be greatly appreciated. Thanks!

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Old 12-08-99, 01:42 AM
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It is the nature of a hollow chisel mortising bit to stick on the first hole. They usually stick worse in soft woods than hard since the sides of the hole aren't as "clean". Using wax as you are is a good way to help decrease the friction. If the auger bit is of the proper diameter, it should be just slightly larger in diameter than the chisel is square. I think that lowering the bit will only make the problem worse. It should generally be up into the chisel as far as it will go without generating undue heat. I have tuned up the inside of the chisel by smoothing out any burrs or mill marks left from the machining process. Also, make sure that you are using the holddown fingers that should come with the mortising attachent & adjust them down as close to the top of the workpiece as possible. About 1/16" is good. This doesn't change the friction any, but makes it easier to grunt the bit out of the wood.

[This message has been edited by The Timber Tailor (edited December 08, 1999).]
Old 12-11-99, 02:58 PM
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You didn't mention the prior amount of useage on the chisel. If it's NEW, it should not bindup, in my opinion. If it's worn from many prior useages, it may need sharpening.

What happens to ALL shop cutting tools, besides becoming dull from useage, is the relief angle behind the cutting edge becomes higher, which causes some of the binding.

This also happens from any prior shapenings the tool had, if any. If the person doing your sharpening fails to grind the relief angle back to the orginal angle, binding will occur.

Another possible problem, if the chisel or ANY tool that bores a hole binds up, is if the starting points outside diameter has been decreased. <The starting point is that part of the tool that enters first.>

Should this be the case, the tool for all intensive purposes is junk.

I have been doing professional saw and tool sharpening in my own shop as a vocation for over 20 years.

A professional sharpeners saying:
"I can sharpen anything except the mind and the wits." haha...:-)

Good Luck

'Accurate Power Equipment Company.'
A complete saw and tool sharpening service for the homeowner and contractor.


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