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Going thru an older shear
For quite a few years I had the idea that a gap shear could be used to cut various angle notches in metal but everyone I asked about it looked at me like I was from another planet or told me I needed a notcher. Notchers that are adjustable to cut various angles other than 90 degrees are hard to find used and command high prices so that just never made sense for my small shop. About 2 years ago I finally scored a gap shear and have recently tried my idea on 4 pieces I needed for the reinforcements for the back-gauge.
The first photo shows a trial cut I made on some thin scrap sheet just to try out the idea and see what I may be up against. I found out both sides of the sheet have to be laid out with scribe lines for cuts because you have to flip the piece being cut to make your second cut. I also found out the shears hold downs may not be in the right place to do this operation so I’m considering cutting away the side member (blue arrow shows where) between the table mounting bolts so I can use a heavy C-clamp for a hold down when needed. No one has ever told me this could be done so I used the thin sheet metal as a test piece…. I was a bit worried about possibly damaging the shear. The 2nd photo shows the sheet metal template I made and used to scribe my cuts on BOTH SIDES of the ¼” plate…… more on this later in this post. (3rd photo) From my test pieces I determined that the shear stops cutting 2.500 from the edge of the table that holds the lower knife so I scribed a line that distance and at a right angle to my first cut, then all I had to do was visually line up the scribe line with the edge of my table and the first cut would stop at the correct place. Now I’m considering adding a laser to point where the cut stops, then in the future I wouldn’t need to bother with the scribe line, just line up the laser dot with the tip of my scribed angle on the blank. The fourth photo photo shows the piece after the first cut. You can see how much the rake of the upper knife / blade deflected the sheet. This is why the piece has to be flipped over before making the second cut. It would not be able to sit flat on the shear’s table in this condition. The fifth photo shows the final cut being made. None of the shear’s hold-downs landed on the piece correctly so I held the sheet down with a 3 foot long carpenter’s wrecking bar. Photo #6 says it all….. SUCCESS. My idea actually works. I can notch pieces at any angle I want without an ultra-expensive angle adjustable notcher. What does this mean for you guys making automotive panels ? Just possibly you should consider buying a jump shear that’s a gap shear. Of course you can also cut lengths longer than the shear blade length by sliding the sheet along the back-gauge and making several cuts so it’s pretty important to buy one that has a back-gauge. The down sides to a gap shear is they are bigger (mostly deeper front to back), heavier and rarer so harder to find. Anyway some things to ponder. ~ John Buchtenkirch !!!!!!!!shear15.JPG !!!!!!!!shear26.jpg !!!!!!!!shear17.jpg !!!!!!!!shear19.jpg !!!!!!!!shear20.jpg !!!!!!!!shear25.jpg !!!!!!!!shear28.jpg
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John |
#2
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Its your shear, you can do what you want. If it were mine, or in a shop I worked in and had control of the situation, I don't think I would allow it. Someone is bound to get hurt, the machine is bound to get hurt, or something. It is outside of the original machine design intent.
Perhaps I worked around too many people that pushed machines WAY beyond their limits and seen too many people hurt themselves or machinery. I was the one that had to fix them, or call 911 to get an ambulance on the way. just my .002, which I am sure you asked for Marty
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Glad to see your "theory" worked as expected. To me most machines are only a starting point to help you get where you want to go and modifying them is what metal working and machineing is all about. I do agree with Marty's comments on over modified equipment....just to many boneheads out there that don't think thru their efforts to the end or even more so....think one step ahead of the safety required.
And I'm not sure I understand the difference of a gap shear vs a jump shear George
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George If you are afraid to fail, you will never learn |
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