Drill bits

[pepi]

Have the 750 as well, I believe its advantage is the ability to do 3/4 bits or comes with the chuck.

The biggest mistake I see many make, trying to force the bits. More force dull bits, let the tool do the cutting, and stay sharper longer.

As to coated bits @ this price and I qualify this with the following word "Banggood", it is an affordable price to experiment with.

http://www.grizzly.com/products/TiN-Coat...rizzly.com

My question what is special about them, what materials are they designed for, advantage? I have searched and have not seen anything yet, anyone have a link on the coatings, please post it.

My personal experience thus far.... drilled some rivets on a ball joint for a so/so friend. In return because I bailed him out of a jam. Brought me a Dewalt coated small set 1/16 - 1/4.

After using some of the bits, saw zero difference, think they are less efficient then black oxide bits. So they sit on the bench in a box collecting dust.
Greg

[EdK]

I have the 750 and it works well for me.

Ed

[wawoodman]

An often-overlooked factor, especially by new users who might be following this thread, is the importance of choosing the correct speed. Here is a handy chart:

https://www.fnal.gov/pub/takefive/pdfs/D..._Chart.pdf

[pepi]

Still got this bug for a new set of good drill bits, anyone know or have used these.

http://www.wintersdrillbitcity.com/

They are on my radar, have talked with the owner, sent me his catalog (PDF). A best drill bits search done, these were mentioned on a practical machinist, thread .

Told no pre-drilling, what I call a pilot hole needed, fractions have flats & sells single bits if ya brake one, happens now and then.

Oh and was told to run his bits 350 and below, that btw is something I have started doing since I acquired the mill. Lowered the drill speed using the press also.

All ears or eyes in this case tell me what you think..please

Greg

[Mayhem]

(05-02-2017, 03:08 PM)pepi Wrote: ...Oh and was told to run his bits 350 and below...

Greg

Personally, I set the RPM to suit the diameter of the drill and the material being drilled.

[pepi]

(05-03-2017, 06:58 AM)Mayhem Wrote:

(05-02-2017, 03:08 PM)pepi Wrote: ...Oh and was told to run his bits 350 and below...

Greg

Personally, I set the RPM to suit the diameter of the drill and the material being drilled.

I agree, just took the 350 as a base line or reference. The speed charts, after looking them over have a too fast feel about them.

Drilling is like any other machining process in my mind. If in doubt start at the recommend base line and adjust accordingly.

Greg

[TomG]

350 is the perfect rpm for a 7/8" drill in steel. Using that rpm for smaller drills wastes time and for larger drills, would burn them up. The old standby formula for rpm based on cutting speed works on any rotating tool or workpiece. Just take the cutting speed of the material being cut (100 sfpm for steel), multiply it by 4 and divide by the diameter of the tool or rotating workpiece. A 1/4" drill in steel for instance would be 4 X 100 / .25 = 1600 rpm. Use this formula and you'll never waste time, break an end mill for going too slow, or burn up a drill for spinning it too fast.

Tom

[pepi]

(05-03-2017, 08:21 AM)TomG Wrote: 350 is the perfect rpm for a 7/8" drill in steel. Using that rpm for smaller drills wastes time and for larger drills, would burn them up. The old standby formula for rpm based on cutting speed works on any rotating tool or workpiece. Just take the cutting speed of the material being cut (100 sfpm for steel), multiply it by 4 and divide by the diameter of the tool or rotating workpiece. A 1/4" drill in steel for instance would be 4 X 100 / .25 = 1600 rpm. Use this formula and you'll never waste time, break an end mill for going too slow, or burn up a drill for spinning it too fast.

Tom

Tom,

Thanks I will put this on paper and hang it in my shop, until I have it committed to memory.

Thanks,
Greg

[Mayhem]

I made up an excel spreadsheet that has all the wire gauge, letter, fractional and metric drills up to 1" / 25mm and the recommended RPM for a variety of materials. I printed it out, laminated it and it hangs next to the drill press. I'll see if I can dig it up and I'll post it here.

[pepi]

That would be very nice of you, I for one would print it and post it. Happy hunting, I say that cause I have stuff saved on my computer. That I can never find when I want it. When saved, the folder I placed it in made perfect sence at the time....

Greg