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Need countersink help

mwb315

Plastic
Joined
Oct 31, 2023
I’m applying a .322” 82 degree countersink to a .174” hole using a 6 point, 3/8 x 82 deg countersink bit. This is on 11 ga mild sheet steel using a stand up drill press, because I don’t have a mill.
Brand new countersink bit, 300rpm, have also tried 400rpm

The problem I’m facing is 1. Super fine shavings, (the consistency of Dill Weed) and 2. Funky shaped holes. Any help would be appreciated, I included pictures below
 

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If you can't get the speed down, jam a small 1" square piece of rag in there before cutting the c'sink. Alternatively, if you have a depth stop, use it to limit down travel while cutting. Bump it down as you go.
 
If you can't get the speed down, jam a small 1" square piece of rag in there before cutting the c'sink. Alternatively, if you have a depth stop, use it to limit down travel while cutting. Bump it down as you go.
Piece of rag in where? The pilot hole? I think I’m missing the point
 
Piece of rag in where? The pilot hole? I think I’m missing the point

Yup. Set it right over the hole and jam the cutter in there right on top of it. If it still chatters, fold it over so it's thicker and try again. Sort of a low-tech version of the depth stop technique. It limits the depth of cut that the teeth can take, so makes them take a gentle nibble instead of a deep bite. The deep bite combined with lack of rigidity is what is causing your chatter.

You can often do a pretty good job with a hand drill with variable speed too. Push very hard and spin the drill as slowly as you can.
 
Yup. Set it right over the hole and jam the cutter in there right on top of it. If it still chatters, fold it over so it's thicker and try again. Sort of a low-tech version of the depth stop. It limits the depth of cut that the teeth can take, so makes them take a gentle nibble instead of a deep bite. The deep bite combined with lack of rigidity is what is causing your chatter.
Okay will try that. I’ve got depth stop set on drill press but it’s quite inaccurate and more of a ball park estimate. ($400 Ridgid drill press)
 
Okay will try that. I’ve got depth stop set on drill press but it’s quite inaccurate and more of a ball park estimate. ($400 Ridgid drill press)

If you're using the depth stop only as a depth stop for c'sink size, it won't help you combat this problem. If you want to use it to fight the chatter you've got to set it so that it stops the cutter just as it touches the start of the hole. Then nudge it down just a bit and take another nibble. Then do it again. And again. And again. Until the hole is to size. Much quicker and less hassle to use the rag bodge, though. Single cut are less chatter prone, these methods are more a "right now" solution to work with what you've got.
 
If you're using the depth stop only as a depth stop for c'sink size, it won't help you combat this problem. If you want to use it to fight the chatter you've got to set it so that it stops the cutter just as it touches the start of the hole. Then nudge it down just a bit and take another nibble. Then do it again. And again. And again. Until the hole is to size. Much quicker and less hassle to use the rag bodge, though. Single cut are less chatter prone, these methods are more a "right now" solution to work with what you've got.
Rag has been working, will get through this job and then consider alternative, more permanent solutions. Thanks
 
I’m applying a .322” 82 degree countersink to a .174” hole using a 6 point, 3/8 x 82 deg countersink bit. This is on 11 ga mild sheet steel using a stand up drill press, because I don’t have a mill.
Brand new countersink bit, 300rpm, have also tried 400rpm

The problem I’m facing is 1. Super fine shavings, (the consistency of Dill Weed) and 2. Funky shaped holes. Any help would be appreciated, I included pictures below
too fast, and not ridgid enough setup.
 
Okay will try that. I’ve got depth stop set on drill press but it’s quite inaccurate and more of a ball park estimate. ($400 Ridgid drill press)
those ive used, and are stupid flimsy junk, the head has a ton of play into them from factory and bends too easy when full extension.
any sideways force might as well give up,
there isnt any torque to them, the belt sucks and doesnt work worth a crap on the tensioner
the table its mounted onto pivots easily and allows all the vibration to happen in the workpiece.

AKA its junk, need a more solid machine to do things like this.
 
The problem I’m facing is 1. Super fine shavings, (the consistency of Dill Weed) and 2. Funky shaped holes. Any help would be appreciated, I included pictures below
Setup stability is causing this.
It's chattering so violently that the cutter is bouncing around. Hence the small slivers of chips because it can't stay in the cut long enough to form a bigger chip.
Find a way to make the drill press setup more stable, or find someone with a bridgeport that you can use.
You may be able to buy/make a different size pulley to slow down the drill press spindle if it's belt driven.
 








 
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