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drill big holes

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kthompson
Join Date: Oct 2005
Posts: 5275 South Carolina
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2015-09-04          193538


Have any of you used end mills to drill holes larger than one inch in diameter. (No idea what that is in metric.)
I think 2 flute end mills can be used for that but found end mills at Fastenal with more than 2 flutes they are selling for drilling saying faster and easier on the drill than bit.

I know you can do it but my question is how well can you do it with a drill press. (Know there is no way to hand hold.) Do you have any issue with them slipping in the drill chuck? Know this they cost less.




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candoarms
Join Date: Mar 2007
Posts: 1932 North Dakota
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2015-09-07          193589


KThompson,

I do a bit of milling here at home. I've read a bunch on this issue, as I thought about doing the same thing at one time.

Milling with a drill is a very bad idea. The bearings in a drill press are not designed to be side loaded. Placing a side force against your spindle on a drill press will quickly destroy the bearings.

Milling machines are designed to take the side load being applied during the milling action. As the milling table moves from left to right, front to back, a tremendous side force is applied to the spindle. Tapered bearings (like those on an automobile axle) are required for this job.

For large holes....say over 1" in diameter.....you'd be better off using a metal coring bit. It looks like a hole saw used for cutting circles in wood....but the teeth are made of carbide for metal use. Eye protection is REQUIRED. These things make hot chips by the thousands.

Super slow cutting speeds are required. Most drill presses don't go slow enough. A magnetic drill is a much better choice. You can rent a magnetic drill. Fun to use, too.

Hope this helps.

Joel ....


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kthompson
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Posts: 5275 South Carolina
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2015-09-09          193611


Thanks Joel,

I am not planning on using my drill press as milling machine but sure wish I could afford a good one. Just wondering about using milling bit itself to cut rather than really drill hole. Memory is when I was in a tool shop we did with two edge milling bits.

On the metal coring bit, where do you find that? Also how slow are you talking about? I use to think hole saws were made to cut metal but looking at what such as Lowes have on their shelves they do not really tell you what they will cut.

Please forgive me for been watching too many Alaska shows just thought if the chips are too hot then set the drilling out side in your winter, no problem. kt ....


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candoarms
Join Date: Mar 2007
Posts: 1932 North Dakota
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2015-09-09          193622


KThompson,

You want an ANNULAR CUTTER. These aren't cheap, but they're way cheaper than those huge drill bits....and they remove far less metal when cutting large holes.

If I find you choking over the price of the annular cutters, try one of these. Practice with it on some scrap steel before cutting a hole in something of value.

See link below.

Joel ....


Link:   Metal Cutting Adjustable Circle Cutter

 

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brokenarrow
Join Date: Jan 2004
Posts: 1288 Wisconsin
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2015-09-10          193623


Idealy a 2 flute but three would work. Bottom cutting end mill where the flutes are ground all the way to the center. Idealy three flats and 120 deg. for your chuck to keep from spinning. You could also look into inserted drills. We have some that go to larger than 3" and have taper shanks. (25.4mm = 1") ....


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kthompson
Join Date: Oct 2005
Posts: 5275 South Carolina
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2015-09-10          193624


Joel the Annular Cutter I had seen on line and mistakenly thought were end mills. Yes their price is much better than a twist drill bit. Of course they are not hand held drilling due to design but that pleases me.

Does the kit have arbor to use with drill chuck or must you have something else?

I just spent about half the price of the kit that would have included the 1 1/8 inch twist drill I bought from Fastenal last week. That bit without shank maybe 3 inches long. Not much re-sharpening there.

As to the fly cutter did not know they were also metal cutters. Have had one for wood for many a year and talk about needing low rpms get that out to say 4 inches...lol
For metal fly cutters can you really cut mild steel say even 1/4" thick? Any thicker?

It had been at least two years but maybe five since I had bought bits of inch plus and to me the price has really increased and the availability tighten up. Very few stores here had anything in stock over 1". Have in time past found 1 1/8 at local hardware and I think Lowes. kt
....


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arcwelder
Join Date: Mar 2014
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2015-09-10          193632


Depending on what you have in mind.
I had to elongate the mounting holes on a front end loader mount to line up to my tractor. Couldn't drill new holes without welding up the hole and start over.
So I went to Lowe's and bought a Dewalt trim Router D26670, compact router on sale. It was easier to use than a full size router.
Then ordered 1/4 shaft metal cutting carbide bits from fee-bay.
Scribe the line for the hole, then with hearing protection and Safety glasses, routed out the hole to match up.
What I learned is that you put the bit in the hole, then turn on the router. If you bump the side it will break off the bit. Cuts fast and fairly accurately.
While not perfect, had no problem with 1/2 inch steel.
If you make a guide, you can route through the guide until the non cutting part of the bit is against the guide.
I also used this to make several holes into an adjustment slot.
I think would work for thicker steel, because you can cut a shelf, then lower the bit. ....


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kthompson
Join Date: Oct 2005
Posts: 5275 South Carolina
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2015-09-11          193638


In my years in a heavy equipment manufacture plant one of the best tools I ever saw was a book written now many years ago about what tools you could use to do other jobs than what that tool was sold for. It contained something called common sense (not offered on ebay nor in much of life any longer)and really a necessity for about any DIY or even small operation. In saying that our plant also made use of that same idea with certain machines. It was always interesting to hear the conversation of what machine do we have that can do this new job as most often more than one was offered by that department with what they thought of it's benefits and limitations.

So you use a wood working router with a metal milling bit. Good idea. Know years ago in my small wood project days the idea the best small wood working tools metal cutting tools. Think it was using end mills versus straight router bits.

Thanks for the info. kt ....


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