# Cutting and forming sheet metal



## partsguy (Nov 9, 2017)

All, I have a question. Perhaps, you might have an answer. I am trying to make the bracket below. The left side is a rough prototype, which I refined last night to perfection. I have the tools to cut and bend this to the perfect shape. The only problem I ran into was trying to cut out the half-circle tab at the end. Dad is an engineer and taught me the basics of designing and cutting metal. Taught me everything I know on building things, actually.

However, neither of us know for sure how to cut this hole out without using a stamping press (which is how Huffman did it in the 50's). We tried drilling a small hole at the start and using two different router bits for a Dremel. The first would not cut the steel, it would jump around and ream out the groove. The second bit could not be made to turn.

Does anyone have any suggestions? Would like to get this done, it's a favor for a member who helped me out.

Thank you in advance!


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## THE STIG (Nov 9, 2017)

drill a bigger hole and shape it with a carbide bit or sanding drum


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## partsguy (Nov 9, 2017)

THE STIG said:


> drill a bigger hole and shape it with a carbide bit or sanding drum




Sanding drums are too big (if what I am thinking of is a rubber end with a sandpaper cylinder over it). But the carbide bit is a possibility. Is there maybe a really small jig saw of sorts that, once I drill the pilot hole, can just cut out what I need?


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## RustySprockets (Nov 9, 2017)

If just the one item, I'd suggest trying a diamond-coated coping saw blade for the rough cut, then finishing with a small half-round file.  In fact, the file alone is probably adequate.


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## momo608 (Nov 9, 2017)

I would make the tab a separate piece and weld it in.


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## Andrew Gorman (Nov 9, 2017)

Clamp the piece firmly and use a jewelers saw to make the cut.  They are cheap and useful for all kinds of precision cuts.


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## partsguy (Nov 9, 2017)

momo608 said:


> I would make the tab a separate piece and weld it in.




Do not own a welder, tho it is on my bucket list.


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## partsguy (Nov 9, 2017)

RustySprockets said:


> If just the one item, I'd suggest trying a diamond-coated coping saw blade for the rough cut, then finishing with a small half-round file.  In fact, the file alone is probably adequate.




I do have some very small files for such a job. I like the coping saw idea, and Andrew's jewler saw idea. Slow and steady wins the race!!


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## partsguy (Nov 9, 2017)

I think I will try the coping saw and jeweler's saw methods. Much more precise and more controlled. Thanks, guys!!


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## bricycle (Nov 9, 2017)

A punch can be fashioned from an old socket.


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## DonChristie (Nov 9, 2017)

Rat tail file!


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## kwoodyh (Nov 9, 2017)

Leather punch, they come in all shapes and sizes.


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## rustystone2112 (Nov 9, 2017)

Drill a series of 1/16 or 1/32  holes around the outside close together , break it loose and file the edges


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## TR6SC (Nov 10, 2017)

Lots of excellent advice here.


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## kwoodyh (Nov 10, 2017)

I have the ballistic solution! Christmas is nearly here and if your area of the country is like mine there will be someone set up at the mall selling items cut from sheet steel, it's usually some bootleg college logos like OU or UCSC (go banana slugs) well it's a good chance he has a CNC plasma torch, take one of your mostly finished brackets and see if he can set up to replicate! And your welcome!


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## Craig Allen (Nov 12, 2017)

The reason the Dremel bits are bouncing around is probably because of the rpm's and not holding the work steady enough. Having the work clamped in a milling machine would solve that and just nibble away at the work with small end mills.  In case you don't have access to a milling machine the best advice that was previously posted here is using small files. Slow work, but the most accurate.


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## Craig Allen (Nov 12, 2017)

One small addendum - Using a Dremel grinding wheel will cut better than the router bits and they won't bounce around. Router bits designed for cutting wood don't work the best on metal.


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## partsguy (Nov 17, 2017)

I want to give you all an update. The bracket has been cut, bent, and routed. All the rough work was finished last night. HUGE thank you to everybody who chimed in!

Tonight, I will will drilling the three holes, and filing and sanding all the rough cuts. Lastly, I did end up re-working the first tab and I do have some marks to fill in from the hammering I did. It will painted, tonight or tomorrow morning, and J-nuts will be installed. This will be completing a green Radiobike (not mine). Thank you everyone!!!


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