Largest realistic drill size when drilling metal??

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donpol
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Largest realistic drill size when drilling metal??

Post by donpol »

I've recently used my Shopsmiths to drill some small holes in metal. I don't normally do much drilling in metal, but wanted to find out what the capacity would be for my machines, without stressing them too much. Depending on what speed charts I look at there are various recommendations for maximum drill size based on speed and material. My concern is drilling with a bit large enough that the pressure necessary to push the bit through the material would potentially damage the quill or bend the table.

I have a Mark V and a 10ER. The MKV obviously has a slightly slower speed than the ER which, in theory, would be able to handle a larger diameter bit. The ER has a stronger table mount (cast iron v. aluminum) and would be more resistant to flexing.

Obviously bit size will be somewhat determined by shank size and chuck capacity. But, a 2" silver and deming bit, with a turned down shank would fit in the chuck. I bet using a bit that size would damage something though and probably exceed the design capability of either machine.

So, my question is, what is the largest size of twist drill bit that can be used reasonably in the MKV and 10ER to drill metal; ie. steel and aluminum? Thicknesses up to about 1/2".
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JPG
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Re: Largest realistic drill size when drilling metal??

Post by JPG »

Keep in mind this is supposed to be a 'wood working' machine.

That said, I would not hesitate to chuck up a bit slightly larger than 1/2", but the speed 'minimum' attainable will quickly limit the size.

Although you expressed concern re the table supporting the quill pressure, an even greater concern is the ability to resist the work piece 'spinning'.

If you need excessive quill pressure, the bit likely needs sharpening(yes bigger bits do require greater force).

So a good 'rule' is if the unaltered straight shank fits the drill chuck, ok. Reduced shack is a gamble.

Do not overlook 'cutting speed'.

If it is too large, the SS will tell you soon enough. Pay attention.
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Goldie(Bought New SN 377425)/4" jointer/6" beltsander/12" planer/stripsander/bandsaw/powerstation /Scroll saw/Jig saw /Craftsman 10" ras/Craftsman 6" thicknessplaner/ Dayton10"tablesaw(restoredfromneighborstrashpile)/ Mark VII restoration in 'progress'/ 10
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reible
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Re: Largest realistic drill size when drilling metal??

Post by reible »

A lot of this is self limiting. The standard drill chuck will take bits up to 1/2". If you got larger bits with turned down shanks you could go bigger but when drilling metal you will soon reach a limit of the chucks ability to hold the bit without it spinning the shank. That might or might not happen before the shopsmith limits itself by slipping the belt. And this might be before or after the effort of feeding the quill with the short handle of the drill press exceeds your effort. Also keep in mind some metals work harden so if the bit is not cutting it might well be work harding, and the keep in mind the chips are what take some of the heat away so over heating and wrecking the bit all go hand in hand.

I don't recall ever seeing a number published as to a limit but as I said there are many things that limit how things work rather then just the capacity of the machine. Most drill presses do not have the horsepower of the shopsmith but have better ways of chucking etc.

Ed
{Knight of the Shopsmith} [Hero's don't wear capes, they wear dog tags]
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BuckeyeDennis
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Re: Largest realistic drill size when drilling metal??

Post by BuckeyeDennis »

Keep in mind that you don't have to remove the entire hole diameter at once. Having the torque and force capacity to drill a big hole in one pass is important if you're a production shop. But for occasional users like me, it's really not necessary.

You can start with a small drill, and then incrementally enlarge the hole. I find that a step reamer/drill works great for thinner stock. Some people don't like them, but my Irwin step reamers have always cut clean and true for me, without grabbing. Which is more than I can say for my twist drills. I also find them to be a great tool for chamfering holes, because they are self-piloting in all the most common hole sizes.

For thicker stock, you can use a succession of increasing-diameter twist-drill bits, in which case starting the hole with a center drill will help keep things true.
Mike907
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Re: Largest realistic drill size when drilling metal??

Post by Mike907 »

I don't know if this helps, but the Power Pro speed chart has listings for drilling iron/steel up to 1/2", and for drilling non-ferrous metals up to 3/4".

Mike
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skou
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Re: Largest realistic drill size when drilling metal??

Post by skou »

You guys are overlooking the obvious here.

You don't need to drill away ALL the metal
in a hole, just the outside edge.

http://www.aliexpress.com/item/18-35mm- ... .14.YXda5x

And, yes, I'd use the Model 10. Get the speedchanger,
or a jackshaft setup, and you're in like Flynn.

steve
10 ER, stripped down.
Basic 10ER, Parts machine. Will be a semi-dedicated drill-press machine.
10 ER, a "survivor" of the trailer fire, in the back yard, needing restoration. Has a Mk5 headrest. Finally, stripped down.
Numerous parts, for Model 10 stuff. Except for lower saw guard, A and B adapters, I've got it.

Looking for one more, or some 9 inch extension table raisers.
TheGoodMorty
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Re: Largest realistic drill size when drilling metal??

Post by TheGoodMorty »

Does the "speed reducer" add-on part help this at all? Is that what you're referring to, skou?
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JPG
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Re: Largest realistic drill size when drilling metal??

Post by JPG »

TheGoodMorty wrote:Does the "speed reducer" add-on part help this at all? Is that what you're referring to, skou?
He is referring to the model 10 speed changer which in low range goes down to 425 rpm.
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╟JPG ╢
╚═══╝

Goldie(Bought New SN 377425)/4" jointer/6" beltsander/12" planer/stripsander/bandsaw/powerstation /Scroll saw/Jig saw /Craftsman 10" ras/Craftsman 6" thicknessplaner/ Dayton10"tablesaw(restoredfromneighborstrashpile)/ Mark VII restoration in 'progress'/ 10
E[/size](SN E3779) restoration in progress, a 510 on the back burner and a growing pile of items to be eventually returned to useful life. - aka Red Grange
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skou
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Re: Largest realistic drill size when drilling metal??

Post by skou »

JPG wrote:
TheGoodMorty wrote:Does the "speed reducer" add-on part help this at all? Is that what you're referring to, skou?
He is referring to the model 10 speed changer which in low range goes down to 425 rpm.
No, I'm referring to a core drill.

A core drill, only removes the outer
dimension of a hole.

So, you're not removing the WHOLE
hole, just the outside of the hole.

But, thank you, JPG, Couldn't have
done it with out you.

steve
10 ER, stripped down.
Basic 10ER, Parts machine. Will be a semi-dedicated drill-press machine.
10 ER, a "survivor" of the trailer fire, in the back yard, needing restoration. Has a Mk5 headrest. Finally, stripped down.
Numerous parts, for Model 10 stuff. Except for lower saw guard, A and B adapters, I've got it.

Looking for one more, or some 9 inch extension table raisers.
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skou
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Re: Largest realistic drill size when drilling metal??

Post by skou »

TheGoodMorty wrote:Does the "speed reducer" add-on part help this at all? Is that what you're referring to, skou?
Yes, the speedchanger WILL give you a slower speed.
You want that, drilling out a large hole.
But, you only need to drill out the outside
of that hole.

steve
10 ER, stripped down.
Basic 10ER, Parts machine. Will be a semi-dedicated drill-press machine.
10 ER, a "survivor" of the trailer fire, in the back yard, needing restoration. Has a Mk5 headrest. Finally, stripped down.
Numerous parts, for Model 10 stuff. Except for lower saw guard, A and B adapters, I've got it.

Looking for one more, or some 9 inch extension table raisers.
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