Need a new drill bit

[Weldangrind]

Where's the best (and cheapest) place to buy a 1-1/16" drill bit? I found one locally for over $40, and I found one on eBay for $17.50 (but it looks like junk). I'm drilling a hole in aluminum and it needs to be true, so I'm nervous about Chinese bits. I'd happily buy a Taiwanese bit, since they've been making decent tools for a long time.

What do you recommend?

[SpudRider]

Wow, that's expensive! 8O I'm sorry I can't help you, Wag. :( However, I hope someone posts a good solution for you very soon. :)

Spud :)

[Reveeen]

What level of precision do you require?

[Barnone]

How about a hole saw? Not accurate enough?

[davidsonsgccc]

i believe the chinese drill bits will drill tru enough as long as you drill a good center or pilot hole for it to follow. starting on center is the key to a straight hole. this is my opinion backed by my experience . good luck

[2LZ]

As much as I hate asking for others services and try to avoid it at all cost, if I was to make a decision between a 40.00 drill bit for one hole and another option, I'd probably opt to call my local machine shop and see if they'd drill it for 5.00. Is the part portable?

[Weldangrind]

Reveeen, there will be a little forgiveness, but I'm hoping for a nice straight bit.

Barnone, I'm concerned that a hole saw will wobble, as has been my experience.

davidsonsgccc, I should have said that I'm enlarging a hole this is ~ 7/8" already, so a pilot hole ins't possible. My hope is that I can center the piece in my drill press vise and slowly open up the hole.

2LZ, I'm gonna think on that some more. The part is very portable, but if anybody is gonna screw it up, it better be me.

[davidsonsgccc]

you may consider finding a 4 flute endmill with a reduced shank for your drill press.

[mizke]

how about a flowjet..lol.. some one here needs to buya flow jet and start cutting some parts..

weld your pretty handy, im sure however you attack enlarging that hole it will turn out how it should

[Weldangrind]

you may consider finding a 4 flute endmill with a reduced shank for your drill press.

I thought about that. I found MT tapered bits on eBay for less, but it would limit use to an MT equipped device. And end mill would be useful on the lathe, for sure.

[Weldangrind]

how about a flowjet..lol.. some one here needs to buya flow jet and start cutting some parts..

weld your pretty handy, im sure however you attack enlarging that hole it will turn out how it should

Thanks Mike. :)

[dmmcd]

What thickness aluminum? I wouldn't think you would need an expensive bit, Al drills really easy. You shouldn't dull a cheap bit in one hole, especially if it is already at 7/8". I usually buy my stuff for work from McMaster, but I think in that size you are looking at a minimum of $40 and up from there. Or borrow one from a local machine shop, or maybe rent one? I have a few 1" bits that are worn that I would send you, and you could sharpen them, but that obviously won't do you any good...

[Jim]

The part is very portable, but if anybody is gonna screw it up, it better be me.

:lol: :lol: :lol:

[Weldangrind]

dmmcd, the material thickness is about 1", and it's already drilled out to about 1/2". I have a couple of 1" bits as well, and I might try them just to practice before the final size. As you say, Al drills easy.

What do you like for cutting fluid with Al? I use Rapid Tap, but mostly on ferrous metal.

[dmmcd]

I don't use anything usually for cutting fluid, but you might want some water in a spray bottle as coolant. You can easily melt the aluminum if it gets too hot, which is a bad thing, trust me... But a 1" piece is going to take a LOT of heat to melt. Use a fairly high spindle speed, but don't apply too much pressure.

[Weldangrind]

Thanks for that tip. I have my drill press slowed down as much as possible for steel, but I can see the logic in speeding it up and using light pressure with Al. Any recommendations on spindle speed?

[2LZ]

Thanks for that tip. I have my drill press slowed down as much as possible for steel, but I can see the logic in speeding it up and using light pressure with Al. Any recommendations on spindle speed?
Well heck ,WAG. On my Rigid floor model, the scale shows for aluminum/brass....the biggest hole is 3/4"/19MM and is at 400-600 rpm's....and it got slower as the hole got bigger. You may want to dig it out with a spoon. 8)

[Weldangrind]

I just looked at a few drill press charts, and they all recommend 1000rpm for a 1" bit in aluminum. I'm glad I started this thread; spindle speed hadn't occurred to me for this project.

Thanks guys. :D

[dmmcd]

As the bit size increases, your tip velocity also increases for the same RPM (v=wr), so you want to slow down the RPM relative to a smaller bit to keep the same tip velocity. My comment about speeding it up was relative to steel. For harder metals you want to go slower or you will burn up the bit. Softer metals like to go a little faster.

Check the charts, but I would think in the 600-800 RPM range for aluminum with a 1" hole.

[david3921]

I would try a forstner bit. I did a fast search and found this;

http://www.proshoppublishing.com/tips_user.html

[Weldangrind]

Thanks David. :)

I thought of that, and my forstner bit set goes from 1/4" to 2-1/8", but it jumps from 1" to 1-1/8", and I need 1-1/16". For the Metric guys in the shop, I need 27mm.

BTW, carbide router bits also work very well on aluminum to round off corners and do light milling. I once met a guy with a '50 Ford who had created his own side window molding that way.

[david3921]

I've used router bits on aluminum myself that's why I thought of the forstner would work.

[Weldangrind]

I agree with you. Unforunately, even if I could find a 1-1/16" forstner bit, I'm not likely to ever use it again. At least a 1-1/16" spirol bit has a chance of being used again in my lifetime. :lol:

Thanks again for the idea. :idea: This brainstorming session is likely to produce a solution.

[davidsonsgccc]

300 rpms is about 80 % surface footage that is about standard for hss drill. aluminum can go a little higher but unless your drill press is really rigid i wouldnt reccomend it. if your spindle isnt that rigid it could possible egg the hole alittle. plenty of tapping oil or water and easy feed should make a good hole. just my opinion. and you know what they say about opinions :lol:

[mizke]

not to thread jack but im a little confused after reading this page.

for drilling a hard metal high speed is not the best option ? 800rpms seems fairly slow to me, but then again i am so accustomed to wood working since i built staircases for 7+yrs

[dmmcd]

With metals, the harder the material, the slower the speed. If you get into real hard metals, you need special bits such as carbide and diamond. I still use HSS bits on most steel alloys like chromoly, but they don't last as long.

[mizke]

what does hss stand for ?

[Weldangrind]

High speed steel. It's generally the least expensive bit.

I have an index up to 1/2" (plus several larger bits) that are all HSS, and I have one index of cobalt up to 3/8". Cobalt is usually (bot not always) identified by a rainbow colour, whereas HSS is usually black. I've had very little luck with titanium coated bits.

I usually find that a nice, slow spindle speed with plenty of Rapid Tap will drill through mild steel with little effort. just don't pull too hard on the quill.

Interestingly, cobalt doesn't go through wood without burning it, but it's the only bit that will easily go through stainless.

[davidsonsgccc]

the titanium coating will only really make a difference at high rpms where it will help withstand the heat. being slightly harder than hss it would probably chip and wear more quickly than a good hss drill.

[katoranger]

I have learned alot about drilling metals in this thread. My drilling experience is pretty limited.

[waynev]

I'd just use the hole saw, can you clamp a pc of something on the one side of the existing hole so you can use the pilot on the hole saw?

[Weldangrind]

Most of the hole saws I've used have not been very accurate, and as well, I haven't investigated a 1-1/16 hole saw. Thanks for the tip; I'll check at my local tool shop. Maybe they have a good quality hole saw that will work.