Cutting a hole in sheet metal

-
pishta

pishta

I know I'm right....
Joined
Oct 13, 2004
Messages
23,821
Reaction score
13,677
Location
Tustin, CA
Cutting some 80mm holes in 16g plate steel. Do I use a titanium tipped hole saw, or one of those adjustable cutters that fit on a drill and have the 2 bits on a T bar? They say they cut light metal but I'm not sure about that. Any experience? I'd have to use a hand drill on the hole saw as my old 'penny store' drill press has some bad run out and makes hole saws not run true and make some nasty cuts. I could plasma cut these but I'd have to make a wooden stencil to get the circle cut as a circle and not some weird shape.
upload_2022-6-15_11-20-1.png
 
Hole saw.
I have used those t-bar cutters..... in a Bridgeport with a hundred pound vise.
Heck, you will probably need a drill press for the hole saw.

(For what its worth, I have made tens of thousands of holes in 1/4" steel, with a hole saw...... in a bridgeport.)
 
Believe it or not I have cut holes in 1/2" THICK steel AND MORE with hole saws. Use a press that has a VERY slow speed, and LOTS of cutting oil / fluid
 
Another thing you could do is "rig" a mill/ burr/ sanding device in a press, "rough cut the hole slightly undersize by drilling a series of holes all the way around, then clamping the work to scrap board, etc, and rotating it against your burr to smooth the rough hole
 
33IMP said:
80mm is over 3". Never seen a chassis punch that big. (Not saying it doesn't exist, just never seen one.....)
Click to expand...

I have one that's 3.25... 80 mm is 3.14961... Unfortunately I'm in Texas right now & thats not gonna help pishta
 
Find some 16ga. 3" exhaust tube that is swedged open to go over 3" pipe, should be just over 3.13" and use that as a plasma template.

Whats the tolerance on the 80mm Dia. and how "circular" does in need to be?
 
Use this. I’m a retired commercial plumber. These work really well. Milwaukee makes them as well
Cheers!
Dart Guy
9583F21A-3F25-495D-8BB5-9BA349C00B48.jpeg
 
I haven't tried this but.....what about welding a 1/4 x 3" bolt to metal and use a string around it and the plasma head and do a 'ring around the rosy"? Just came up with that ****!!
 
Hole saw was my first choice too but my pos wallowy drill press won't go that slow. That's why I suggested the slower hand drill. I'm trying to make a 1.5mm head shim (looks just like a copper head gasket) out of 16g steel. The 80mm is the bore of the cylinders and I only have about 5mm land between cylinders so it's gotta be pretty close. I could probably get away with the "dotted line" method after a few minutes under the die grinder. COMETIC doesn't make this application. If I had a mill, this would be made by now and I'd be selling extras for $40 online, half what they cost new and not in only .020....
 
Bimetal hole saw will work great. To keep it from trying to ‘walk’ , after drilling the pilot hole replace the bit ‘I am assuming 1/4”with a smooth 1/4” rod.
I used the smooth section of a long 1/4”grade 8 bolt.
When cutting hole use a little thread cutting oil and operate the drill slowly. A hand drill can do this easily using minimal pressure.
Let the saw cut, don’t need to force it, be patient. I have cut holes in the hood of my car and 3/8” metal doing this.
Yote
 
clementine said:
I haven't tried this but.....what about welding a 1/4 x 3" bolt to metal and use a string around it and the plasma head and do a 'ring around the rosy"? Just came up with that ****!!
Click to expand...
That method is sound. I made a science project with my son that showed reflection angles. We took 2 points and put nails in them then took a loop of string larger than the 2 points and looped it around them. Took a sharpie and stretched the loop taught on both of the nails to make a triangle and continued to draw the oval with the sharpie so it was an oval around the 2 points. We then put a 1" border following the oval line and lined it with reflective foil. Took a laser pointer and set the tip on one of the nail points and wherever you pointed the laser pointer within the oval, The reflection would pass over the other point. Got the idea from an oval pool table demonstration with 2 balls on the points: wherever you hit one of the balls, it will bounce back and hit the other ball minus and english you put on it.
 
You're far better off doing it in the dress press because you won't be wobbling it around like you will with the hand drill.
Since you mentioned your drill press is to fast I can help you out with that. Below is the link to the very 15 amp Electronic Fan Speed Controller I use on my drill press when the slowest pulley just won't do it. If you buy one of these units you'll be able to do a lot of things on the drill press you never thought possible.

https://www.amazon.com/dp/B07T9BLJ7L/?tag=fabo03-20

Vsriable-Controller.jpg


Tom
 
pishta said:
Hole saw was my first choice too but my pos wallowy drill press won't go that slow. That's why I suggested the slower hand drill. I'm trying to make a 1.5mm head shim (looks just like a copper head gasket) out of 16g steel. The 80mm is the bore of the cylinders and I only have about 5mm land between cylinders so it's gotta be pretty close. I could probably get away with the "dotted line" method after a few minutes under the die grinder. COMETIC doesn't make this application. If I had a mill, this would be made by now and I'd be selling extras for $40 online, half what they cost new and not in only .020....
Click to expand...
Oh wow Man, for that engine you are conquering? I get it now!
 
pishta said:
That method is sound. I made a science project with my son that showed reflection angles. We took 2 points and put nails in them then took a loop of string larger than the 2 points and looped it around them. Took a sharpie and stretched the loop taught on both of the nails to make a triangle and continued to draw the oval with the sharpie so it was an oval around the 2 points. We then put a 1" border following the oval line and lined it with reflective foil. Took a laser pointer and set the tip on one of the nail points and wherever you pointed the laser pointer within the oval, The reflection would pass over the other point. Got the idea from an oval pool table demonstration with 2 balls on the points: wherever you hit one of the balls, it will bounce back and hit the other ball minus and english you put on it.
Click to expand...
I went to a Bowling Alley to play pool, while visiting Uncle Sid in the late 80s. Man, we didn't have laser pointers then.. but my eyes did! Couldn't miss one shot, as the whole table had a dim chain link style grid that would super electrify where you pointed the stick...
 
Ironracer said:
Yeah, I never figured they would cut anything but drywall, and I have netter tools for that! Lol
Click to expand...

Tried it on wood also but it has to be perfectly vertical or it is nearly impossible with a hand drill. A drill press was better but far from being a decent job .
Yote
 
As stated, use plenty of cutting fluid & minimal pressure. Let the hole saw do the work, maximum pressure & trying to force it to cut equals work hardened metal.
 
I think the plasma and some circle frames would do the job, finish the rough edges with a rat tail file and make sure its sanded smooth. I just bought a handful of 1/4 inch woodruff keys and they are wide enough to make a 2 degree (1.7) offset bushing: file a step on the right bottom and top left. That will advance the cam to the crank enough to negate the shorter cam to crank distance without needing a head shim. Standard compression is gonna take a little bump but it is what it is. Non interference motor.
 
You must log in or register to reply here.
-

Back
Top