3-flat bits VS regular bits... Advantages & Disadvantages?

[techenthusiast]

The bits I've been seeing have either 3 flats or they are just straight...

From what I understand the 3 flats grip better,

What are the advantages of a straight bit as opposed to the 3 flats? And the other way around?

Couldn't you just grind 3 flats into a straight bit if you wanted to?

Thanks

 

[kazlx]

If you use a sharp bit and a chuck that's not clapped out, it shouldn't matter.

 

[techenthusiast]

If you use a sharp bit and a chuck that's not clapped out, it shouldn't matter.

what about the difference between jobber's length and mechanic's length?

i bought the jobber's length HSS black oxide and bronze Triumph bits (under the snapon brand Thunderbit) thinking that because they are longer, they may not fit tighter places, but over time they will last longer because i can sharpen them more times... any input about this?

 

[kazlx]

I use screw machine length just because they don't wander. Precision Twist, around $80 for a set in 1/16ths up to 1/2 through Enco on sale. Can't beat it. Sharpen or replace as needed. Unless you are running production, regular uncoated bright HSS is hard to beat....

 

[kazlx]

http://www.use-enco.com/CGI/INSRIT?PMAKA=317-9912&PMPXNO=19503322&PARTPG=INLMK32

 

[techenthusiast]

Thanks but that doesn't answer the question that I just asked , I'm not looking for a set I already got
One but I'm looking for feedback on my other question,


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[kazlx]

Jobbers are longer with no flats. They are intended to be used on a drill press or something rigid. I believe the mechanics have the flats and are shorter.

Are you using them on a drill press or just in a hand drill? There is a possibility the longer ones won't fit places, but chances are the drill bit isn't going to matter that much. IMO, it's not worth having a thousand bits just in the chance you might need one. I have a couple good sets I use all the time and buy other one-offs as I need them.

My point is, your set is fine. If you really get stuck because you absolutely need a shorter bit, just buy one bit.

 

[jjjrmx5]

Thanks but that doesn't answer the question that I just asked , I'm not looking for a set I already got
One but I'm looking for feedback on my other question,

Yes. Mechanic's length drill bits are shorter than jobber length.
How much so? I've never done a comparison, but I'd say about a 1/4 of the length shorter.

The flats are there for better grip on the shaft (insert dirty joke here-LOLZ) but older bits never used the flats design.

Mechanic length may help you out if space is at a premium, but I see them more as a marketing ploy to sell low volume products as a solution. A lot of folks may buy them, but I see them more as niche bits. But that's just me.

Most machine shops, maintenance depts and production facilities I know use jobber and machine screw lengths (stubby) and even drill length (long) bits as SOP. Easy to source and affordable if bought in bulk.

Jobber lengths are great for wood working and plastics and alum drilling and I often drill out steel spot welds with jobber lengths using a drill press with no problems and no flex.

If you need short bits, as mentioned above, buy a set of machine screw lengths.
I sharpen them all the time and never have a problem.

Only you know what you need. If only a one-off job, just buy what you need.

Good luck.

 

[Provincial]

The web of drill bits is made thinner as it gets near the tip. As you regrind the cutting edge, you work your way into the thicker web. To an extent, you can compensate for the thicker web with grinding technique, such as "splitting" the point, but eventually the web becomes so thick that the bit won't cut properly.

The jobber's length drill may have a little more "sharpenable" length, but not much.

I use jobbers length bits almost exclusively. They don't have enough drawbacks in terms of starting holes, flexing, and access to invest in shorter sets. They are long enough to drill full depth on 95% of the projects I do.

Screw machine length bits don't have as much flex because of their short length, and also are less prone to wandering when starting a hole. They are good for shallow holes or thin materials.

Mechanics length bits are a compromise between jobber and screw machine lengths. My guess is that they would be long enough for about 60% of what I do.

I keep a few long drills around. Most have long flutes, but a few just have long shanks with normal flute lengths. The long shank bits are for reaching into places that I can't fit a drill motor in to and for aligning holes in items with a space between. The long flute bits are for drilling very deep holes in solid materials.

 

[2oolhound]

If you're in a bind because your drill is too long you can hack the **** off with a zip disc but if you're in a bind because your drill is too short you're screwed.

 

[ladarisyuan]

They are intended to be used on a drill press or something rigid.

 

[kenburkholz]

I think the reason for what they call "flatted" shank bits is primarily for keyless chucks which will never have the clamping force of a keyed chuck. Also, the flats will keep the bit from spinning even with keyed chucks when drilling into hard material, or material that has a tendency to grab, such as brass. Ken.