Chisel mortiser bits snapping-now what?
#11
  
About 6 months ago I snapped the end off from a 1/4" bit. I purchased another (Fisch?) and started to use that. I cut a few mortises today and bang!, snapped another.

The cross section that holds that size bit together is a little larger than a piece of rice. I'm not kidding. Those bits take a beating and the small ones obviously don't last long at least for me. I am pushing on the bit (with a dedicated mortiser) just enough to cut wood (usually cherry). Its relatively new so its sharp or should I say was sharp.

Should I move up to a 3/8" mortise for 3/4 wood? Is there a better quality bit for sal?

Help!

Thanks,
Mark
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#12
  Re: Chisel mortiser bits snapping-now what? by sawnuts (About 6 months ago I...)
Here's some info from POP Woodworking. I like to remove most of the waste with a forstner bit in a DP, then finish with a mortise bit.

...."Tenon thickness: This one gets debated a lot, and with good reason. Traditional texts say the tenon’s thickness should be one-third the thickness of the stock being mortised (an important distinction). So if you are joining two pieces of 3/4″material for a door, the tenon should be Ã?¼” thick. If you are joining a 7/8″-thick apron to a 1-1/2″-thick table leg, the tenon should be 1/2″ thick.

Some modern texts say the tenon should be one-half the thickness being mortised , not one-third. My opinion is that this difference relates to the tools being used. If you mortise by hand, with chisels, the one-third rules makes more sense in my experience. Using a 3/8″-wide mortise chisel on 3/4″-thick material invites destruction in many cabinet woods.

But if you’ve ever used a hollow-chisel mortiser, then you’ve probably been amazed at the difference in performance between the 1/4″ chisels and the 3/8″ chisels. The 1/4″ chisel gets clogged up much more easily because its escapement is much small. Plus, the hollow-chisel mortiser doesn’t put the kind of lateral strain on your work that hand-mortising does. So a 3/8″-wide mortise works with machines....."

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#13
  Re: Chisel mortiser bits snapping-now what? by sawnuts (About 6 months ago I...)
(01-22-2020, 06:20 PM)sawnuts Wrote: About 6 months ago I snapped the end off from a 1/4" bit. I purchased another (Fisch?) and started to use that. I cut a few mortises today and bang!, snapped another.

The cross section that holds that size bit together is a little larger than a piece of rice. I'm not kidding. Those bits take a beating and the small ones obviously don't last long at least for me. I am pushing on the bit (with a dedicated mortiser) just enough to cut wood (usually cherry). Its relatively new so its sharp or should I say was sharp.

I think your issue might be sharpness; a new bit does not equate to a sharp bit, and its not just the bit, the chisel should be sharp as well.  In the past when my benchtop mortiser was new to me I had the same thing happen, but once I paid more attention to sharpening both the bit and the chisel (the latter from the inside only, with a dowel wrapped in 500 grit wet dry) things became much better.  My theory being that you have to have crisp cuttings for them to pass through and exit the bit/chisel.  Worth a try.
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#14
  Re: Chisel mortiser bits snapping-now what? by sawnuts (About 6 months ago I...)
Also make sure your Mortise bit is square to the wood.
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#15
  Re: RE: Chisel mortiser bits snapping-now what? by med-one (Also make sure your ...)
Or use a router with any bit you want for excellent results.  When the bit finally gets dull, chuck in a new one.  

John
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#16
  Re: Chisel mortiser bits snapping-now what? by sawnuts (About 6 months ago I...)
Right after I purchased my hollow chisel mortiser I snapped a couple of bits. They were all 1/4". I thought I was probably forcing the feed rate a little, so I slowed way down on the smaller size bits. Haven't broken one since.
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#17
  Re: Chisel mortiser bits snapping-now what? by sawnuts (About 6 months ago I...)
Thanks everyone,

I found that I have a 5/16" bit in my set and that will be the one I use in the future. I can't see where having a tenon 1/6" larger is going to cause any issues with anything and I'm hoping the 5/16" is stronger.

Mark
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#18
  Re: Chisel mortiser bits snapping-now what? by sawnuts (About 6 months ago I...)
I don't ever remember breaking one. I have the Jet mortiser, and the jet branded bits that came with it. Plus some grizzly branded bits.
None of them were really sharp out of the box, so a good touch-up really helps.
Steve





 
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#19
  Re: Chisel mortiser bits snapping-now what? by sawnuts (About 6 months ago I...)
I do not know much about routers but thinking of these things

1.  How deep did you put the shaft of the bit into the router?  If not far then it will break.

2.  How deep are you trying to cut at one time?  I would not go more then 3/16 of an inch

3.  How much were you pushing it?  I would just let the router make its own pace.

4.  Is it a quality bit or from China?

5.  Hard wood or Soft wood?  Hard wood would be easier to break the bit  with the above 4 questions
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#20
  Re: Chisel mortiser bits snapping-now what? by sawnuts (About 6 months ago I...)
Buy the Powermatic chisels/bits.
Wood is good. 
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