Best drill bit and drill speed?

[TNhobbyfarmer]

I need to drill a large number of a 1/2 inch holes in 1/8 inch wall steel tubing. I will use a drill press. What will be the best (longest lasting) type drill bit to use? Also, what would be good RPM speed to use?

 

[whistlepig]

Around 700-800 RPM for drilling mild steel. Cobalt drills last a little longer than high speed drills but cobalt is brittle, easy to break, and more expensive than high speed bits. You may want to consider a Unibit. These work well on thin walled pipe. A good cutting oil will greatly increase the life of the drill bit.

 

[mikehaugen]

what is a "large number of holes?" I like the dewalt pilot point bits because you can do a 1/2" hole in one shot. They last reasonably long (especially in a drill press) but they can't be resharpened. I haven't bought them for a while... the ones I have are made in Germany, I think the new ones are made in China or Taiwan so I don't know if they are as good. They are HSS, and as posted above, that is probably the best for your situation. Though using a drill press you may be good with the cobalt bits. The unibits are a good suggestion, and they do well in thin metal, but if you are doing a couple hundred holes I think they are too expensive and you would be better off with good regular bits. You can probably buy 5 or 10 decent twist drills for what a unibit costs and if you are doing them all the same size, you are not getting the advantage of the unibits.

 

[PILOON]

I need to drill a large number of a 1/2 inch holes in 1/8 inch wall steel tubing. I will use a drill press. What will be the best (longest lasting) type drill bit to use? Also, what would be good RPM speed to use?

Lowest speed you can do on the press and use cutting oil and you should be able to do a ton of holes.
Naturally a good bit is what you want, like Dormer is one top brand.

 

[whistlepig]

Too low of speed and the drill bit will grab and chip the edges. Too fast of speed the drill bit will burn up. It's best to use the recommended SFM when using high speed tooling. The recommended SFM for high speed tools in mild steel is 100 SFM. That works out to be 746 RPM with a 1/2" drill bit.

 

[sal64]

HSS Bright Finish 118° Jobber Drills - Jobber Length Drill Bits | MSCDirect.com

 

[SPYDERLK]

I would use about 400RPM for the 1/2" ... but I would drill a 1/4 pilot first and then go to a Unibit, as mentioned, due to thin wall. Square or round tubing?

 

[flusher]

I need to drill a large number of a 1/2 inch holes in 1/8 inch wall steel tubing. I will use a drill press. What will be the best (longest lasting) type drill bit to use? Also, what would be good RPM speed to use?

What's the diameter of the tubing? If it's 1" dia or more and with only 1/8" wall, I'd use a step drill at 150-200 rpm like electricians use to drill holes in circuit breaker boxes, etc. I'd be concerned about out-of-round holes using a twist drill in your thin-wall tubing.

Good luck

 

[TNhobbyfarmer]

I would use about 400RPM for the 1/2" ... but I would drill a 1/4 pilot first and then go to a Unibit, as mentioned, due to thin wall. Square or round tubing?

Rectangular

 

[SPYDERLK]

Rectangular

Good ... better for the bit than round. Anyway, as previous noted, it will be difficult to get round holes at 1/2 size on 1/8 stock unless you use a UniBit. Beware of the HF step drills. They seem to all be undersized - probably the nearest metric inch equivalent. For just using 1/2" possibility - -If you have a vise setup you could drill a pilot hole in thicker metal and then use that to stabilize the bit for each hole.
... Or you could drill a slightly smaller hole and use a tapered reamer such as McMaster Carr item # 3089A15 to finish.
larry

 

[muddstopper]

Sioux Tolls makes an excellent hole broach set that will make round holes in your metal. http://www.siouxtools.com/kSuite/cmsLite/content/file/SiouxLit/Drills/Vac-Force_Brochure.pdf
Scroll down to the 3rd page. I have one of these sets and it works great in everything but thin, (26guage) metal. It would probably be alright in the light guage metal as long as you put something below to keep the teeth from grabbing the metal. Warning, if you plan on using this setup in a hand drill, replace the push pin with a small drill bit, otherwise the broach can grab and break the bit. In a drill press nothing will drill faster or make a cleaner (round) hole

 

[texasjohn]

consider getting a drill doctor... a sharp bit is your best friend..I waited too long to get one...they truly work and put a good edge back on a dull bit which vastly improves drilling speed

 

[brucewj]

Sioux Tolls makes an excellent hole broach set that will make round holes in your metal. http://www.siouxtools.com/kSuite/cmsLite/content/file/SiouxLit/Drills/Vac-Force_Brochure.pdf

Where can these be purchased and how much are they? I tried looking on their website but get "item not found"

 

[Scooby074]

Where can these be purchased and how much are they? I tried looking on their website but get "item not found"

Item # 278. Here: Sioux Tools Portfolio

No idea on cost though.

EDIT: found one price, Sioux Tools Inc 278 Price: $285.6. $285. Sioux tools are industrial grade, mostly made in USA.

You could try Blair tools on Amazon. They make Rotabroaches too. Made in USA. Cheaper price. http://www.amazon.com/s/ref=bl_sr_a...ld-brandtextbin=Blair Equipment&node=15684181

 

[brucewj]

Thanks,
I appreciate it.

 

[muddstopper]

I will say this, I didnt know the souix tool 278 cost that much. I bought mine direct at the company head quarters in Murphy. I think I paid like $25 or $30 for it just a few years ago. Seeing that $285 price tag makes me wish I had went ahead and bought the metric set while I was at it.

 

[SPYDERLK]

I will say this, I didnt know the souix tool 278 cost that much. I bought mine direct at the company head quarters in Murphy. I think I paid like $25 or $30 for it just a few years ago. Seeing that $285 price tag makes me wish I had went ahead and bought the metric set while I was at it.

Its apparently a price on the whole set of core bits up to 1". These arent good for pieces that arent firmly restrained. Starting the hole is an issue. Not ideal for the OP.
larry

 

[npalen]

Unibit 3/16"x1/2" #2 Step Drill (10232) - Specialty Bits - Ace Hardware
You can get these from Harbor Freight, as someone mentioned above, but the quality of this Irwin is probably better. I too would recommend using a step drill like this.

 

[muddstopper]

Its apparently a price on the whole set of core bits up to 1". These arent good for pieces that arent firmly restrained. Starting the hole is an issue. Not ideal for the OP.
larry

I did buy the complete set, 4 or 5 cutters with arbor. Thats why I am so suprised at what that one company is selling the set for. As for starting the hole, yes these bits are best used in a drill press where the piece being drilled is properly clamped. That is not to say that if you replace the center plunger with a drill bit, this tool cant be used in a hand held drill. I do it all the time, you just have to be careful and not wobble around with the hand drill and not try and force it thru the metal. Just like using a bi-metal hole saw, if you wiggle the saw around, the hole will be wallowed and the saw will jerk and grab. Of course if this set of bits does indeed cost $285, and that one company isnt grossly overpriceing the set, I would probably look for a cheaper alternative for use in a hand drill.