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How to make a 0.75" Hole in Stainless Firewall?
- Thread starter DHeal
- Start date
Mike S
Senior Curmudgeon
BillL
Well Known Member
Drill Bit -NO - NO - NO
Unit-bit - OK
but make it one step undersize and then use a carbide burr or sand out to size. Be very careful - - don't touch it until sanded to final smooth.
If the undersize looks good, no distortion tearing etc. then go for the next one, otherwise use method above.
Best - punch! - still have to sand the burr
YMMV
Unit-bit - OK
but make it one step undersize and then use a carbide burr or sand out to size. Be very careful - - don't touch it until sanded to final smooth.
If the undersize looks good, no distortion tearing etc. then go for the next one, otherwise use method above.
Best - punch! - still have to sand the burr
YMMV
Last edited:
Rotacut sheet metal hole cutters
I didn't have much luck with a unibit. Caught just as it was going through.
Much better luck with a rotacut sheet metal hole cutter. Back up the inside of the hole with a piece of plywood.
http://www.hougen.com/cutters/sheet-metal-hole-cutters/Rotacut-sheet-metal-hole-cutters.html
I didn't have much luck with a unibit. Caught just as it was going through.
Much better luck with a rotacut sheet metal hole cutter. Back up the inside of the hole with a piece of plywood.
http://www.hougen.com/cutters/sheet-metal-hole-cutters/Rotacut-sheet-metal-hole-cutters.html
LifeofReiley
Well Known Member
Larry DeCamp
Well Known Member
SS hole
The rota cut style will work. I used a high dollar carbide unit ( my brother in laws) and it was beautiful. If you only need one hole, try a cheap one.
The rota cut style will work. I used a high dollar carbide unit ( my brother in laws) and it was beautiful. If you only need one hole, try a cheap one.
Hi David, Just did one in my six..... Used a uni-bit, but started with a standard drill bit for the pilot hole. Center punch... drill 1/8"... then 1/4" then uni-bit. Used a battery drill motor on low speed-high torque and used a little cutting oil. Go slow and use firm pressure to keep it cutting. Did a nice job.
The SS might be too thin to punch without adding a layer of scrap to the area.
I used the 1 inch punch from aircraft spruce:
http://www.aircraftspruce.com/catalog/topages/knockout2.php
As said worked great just needEd to debur the edges a bit when done.
Adding a layer of scrap sounds like a good idea just to be sure... .
Doug
Well Known Member
Bob Avery's Rotabroach tool is a delight to use for just this purpose. A little 'exe' but hurts only once.
David-aviator
Well Known Member
Unibit worked here.
50 caliber is not quite large enough or it could be an option.
50 caliber is not quite large enough or it could be an option.
I have used somehing very similar for 30 years - it works great. A pilot drill #40 then use the cutter for the size you want. They are sold by many companies as "Spot Weld cutters" Avery's set is very nice.
DHeal
Well Known Member
Follow-up: I used my trusty Uni-Bit tool and a touch of coolant to make a very round/neat 0.75" hole. As expected, it left a pretty good-sized burr on the outboard side of the hole which was quickly smoothed with a Dremel grinder bit and deburring tool. Thanks for all the input!
ps -- While an interesting idea, use of a 1911A1 was considered but deemed not legal - this is California don't ya know.
ps -- While an interesting idea, use of a 1911A1 was considered but deemed not legal - this is California don't ya know.
n82rb
Well Known Member
would you suggest a wadcutter and how many grains?
rzbill
Well Known Member
Yeah, full wadcutter, not an SWC since it can be hand chambered. Low powder load, like 4 grains?
