Safe fixturing question for a cutoff operation

markba633csi

markba633csi

Mark Silva
H-M Supporter Gold Member
I need to cut the bottom off a 22 ga. stainless steel water bottle. The bottle is about 2.75" diameter. I wanted to build a fixture to hold my 4.5" angle grinder to the bench, mount a 1/16" Norton cutoff wheel, then perform the cut by holding the bottle against the bench and rotating the bottle (with safety gear on of course) as I bring it into the wheel.
In the picture, which is the safer cutting configuration, wheel cutting down or wheel cutting up? I'm thinking up is less likely to jam and buck. Right?
Mark S.
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This is the equivalent of climb milling. For safety you want the bottle rotating the same direction (CW or CCW) of the cutting disc. That way they are in opposite directions when they meet. Up or down is relative.
Robert
 
Agreed, but do you want to be cutting down toward the table (potentially pinching the work) or cutting up away from the table, which would kick the work up and away- I don't know but it seems safer to do the latter
 
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You want the pressure to be going against a solid surface, not lifting. Saying that, I still wouldn't do what you're thinking
 
You mentioned cut off wheel & grinder so I'm assuming you're planning on using an abrasive cut off wheel & not a toothed blade. If that's the case I would go with the first method.

Wheel spinning down as it engages the work so the sparks fly down & will keep the work pushed against a solid surface. Don't want sparks shooting up into the air nor have to fight trying to hold the work piece down if holding by hand.
 
If you must use an angle grinder with an abrasive cut off wheel, I would much rather secure the workpiece & hold the grinder by hand rather than secure the grinder & holding the workpiece by hand.

If you are going through the trouble of making a jig to secure the angle grinder, sounds like you have to do a number of these? I'm not so sure an abrasive wheel is a good solution if you need to do multiples. Abrasive wheel is messy & will cause a lot of heat, as you know stainless doesn't dissipate heat well, it'll very likely discolor the stainless if that matters.

Do you have a bandsaw, a horizontal preferably? If I had to do multiples I'd use something that cuts/saws rather than grind/abrade. This is similar, what I did for a friend. Cut two pairs of stainless steel mufflers & exhaust tips. 3" mufflers (inlet/outlet) & 3.5" tips cut at a 15° angle. With a bandsaw you'll get a clean straight cut (if adjusted properly), no discoloration, & much safer.


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I’d clamp the bottle and control the angle grinder with both hands. Drill a hole 2.75” diameter in piece of plywood approx. 12” square. Now saw through the wood parallel to one edge so that you split the hole in half. This give you a clamp that will hold the bottle. Use the wood as a guide so that the wheel guard rests on it and gently move the grinder round the bottle cutting as you go.
 
I tried the vertical bandsaw but the carbon blade just skidded off the bottle, wouldn't cut. I figured this stainless is too difficult to cut with a toothed blade and would probably break the blade or strip teeth so I stopped while I was ahead. All my blades are carbon anyhow, and this bottle is too thin.
I thought about holding the grinder but knew the cut would be ragged if I did that- Maybe I'll try MalR's idea
M
ps If I had a big enough lathe I would chuck up the bottle and use a tp grinder with a cutoff wheel
 
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