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Discussion Starter #1
So I needed to put 2.75" and 3.25" holes in 1" thick plate. I didn't want to spend all day trying to machine that big of a whole start to finish on the lathe, so I instead decided to use a hole saw to get 2.5" out of the way, and then use the lathe to finish up the project. I had used big hole saws on 1/4" plate before, and it works fine. Usually I will drill most of the way though on one side and then flip the part to finish it off..

I didn't have a lot of success on 1" plate. I have a big drill press and used the slowest speed, also used tons of oil. It cut about 3/16 or 1/4" deep pretty quickly and then bogged down there. After what seemed like an hour of cutting, lifting to clear chips, cut, lift to clear chips etc. I finally got the first of 4 holes done. So deciding that the issue was the chips had no where to go once the teeth were too deep I decided to try a new tactic. The hole was supposed to be 2.5" diameter so 1.25 radius. I drilled 1/4" holes with their outside edges right at 2.5" giving the chips a place to go as I cut. With drain holes, the hole saw cut through the 1" plate in a few minutes. It took time to drill the 1/4" holes, but the overall process was at least twice if not 3 times a fast as trying to just cut the plate with the hole saw alone... Not required for thinner plate, but if you need to make a big hole in thick plate, you might want to try this technique...
 

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I have used 3/16" holes and for that size hole, use 4 or 6, depends.
I do that whenever the material is just thicker than the teeth are deep, and thicker.
Helps a LOT!
I never thought to share that.
Thanks x-rated!:smokin:
 

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If the part(s) could be held on a lathe,a trepan tool may have worked.
 

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Guess depends on what accuracy you are looking for. If it's a rough hole, then use oxy/acet setup, use plasma CNC, Laser, etc.

Setup time for machines can take up alot of time and overhead.
 

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If the part(s) could be held on a lathe,a trepan tool may have worked.
This! I have used a trepanning bit I ground many times with great success for larger holes...

Your hole drilling tip to let the shavings out has been around for a while and does work great though too! :)
 

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Can you make a machined insert and torch the oversize hole out and weld in the machined piece? That is how I drop in a threaded center in trench plate (1"+ material) for lifting eyes.
 

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Discussion Starter #12
This! I have used a trepanning bit I ground many times with great success for larger holes...

Your hole drilling tip to let the shavings out has been around for a while and does work great though too! :)
I didn't think I invented the technique, but I have been lurking in this forum for years and never seen it mentioned. Thought someone else could use the tip...

Merry Christmas! :)
 

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I didn't think I invented the technique, but I have been lurking in this forum for years and never seen it mentioned. Thought someone else could use the tip...

Merry Christmas! :)
Good tips are worth repeating.... old farts like me keep forgetting them! :flipoff2

Happy New Year,

Tom
 

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You'd have to find a BIGASS mag drill. We have two at work, and drilling 1"+ holes gives them (and me) a workout.
Annular cutters are easy. They're closer to hole saws than twist drills. Converts only the outer 3/16" or so of the hole into chips (vs 100% for a twist drill), the center slug drops right out the center.
 

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Annular cutters are easy. They're closer to hole saws than twist drills. Converts only the outer 3/16" or so of the hole into chips (vs 100% for a twist drill), the center slug drops right out the center.
I know what they are and how they work, I use them at work every day. However even when you're only removing the outer 3/16" of the hole to chips, when you get into larger holes in thicker material the volume of the material removed grows a ton.

As a result of this, the electrical motor has to work harder and more downward pressure is required to get the cutter to bite. Even drilling a 13/16" hole in 1/2" plate isn't a "cake walk" however it is far better than using a twist drill.
 

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Biggest hole I have ever drilled was about a 5" hole with a hole saw in 1/2 HR steel. took about 30 mins. each. Did two.
 

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Drilling 6 holes seems like a lot to get 1 hole that is 2.5".

Want to get 100 holes per saw, 200 holes per saw, 300 holes?

I have a customer using these in a drill press cutting 1-3/16" dia holes into a 2" pipe (perpendicular to the axis of the pipe). Wall Thickness is about .125" and they stopped counting after 350 holes. A good morse, milwaukee, or lenox bi metal hole saw would get 13-15 holes per saw.

I have another customer that drilled at least 180+ holes into 1/8" plate and stainless 1/16". I hope Corey comes on here and tells about it.

Also takes 1/4 the drill time. These can be used in a press, hand drill, or mag press - no noching...yet.


 

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Drilling 6 holes seems like a lot to get 1 hole that is 2.5".

Want to get 100 holes per saw, 200 holes per saw, 300 holes?

I have a customer using these in a drill press cutting 1-3/16" dia holes into a 2" pipe (perpendicular to the axis of the pipe). Wall Thickness is about .125" and they stopped counting after 350 holes. A good morse, milwaukee, or lenox bi metal hole saw would get 13-15 holes per saw.

I have another customer that drilled at least 180+ holes into 1/8" plate and stainless 1/16". I hope Corey comes on here and tells about it.

Also takes 1/4 the drill time. These can be used in a press, hand drill, or mag press - no noching...yet.



Are you stricktly online purchasing? is there a store in Orange?
 

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People can stop by and will call anytime. Someone is there between 7am and 6pm. Send me an email cause I run in and out a few times a day.....
 
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