Stub length vs. Jobber length drills

[kythri]

What's the difference between "stub length" drills and "jobber length" drills?

Huot's got a couple of different empty indexes that I'm interested in, and this appears to be the difference between the two.

 

[jjjrmx5]

Length.

Duh.

LOLZ.

Machine length (aka stubby) is usually used for use in , um, machine tools like drill presses, lathes/screw machines, and mills. Less chance of bit deflection (bending) and in most cases the drill depth is limited.
Jobber =common length. AKA mechanic's length (I hate that term.)
Taper = long.


Whatcha need or missing if you need shorties? 118 or 135 split point?

I'm sharpening a mondo load of mixed and gently used bits for a GJ member and many are machine length. Fractional, letter and #. If you are looking.

I just sharpen. He's the brains and the money man.

If just buying the index, it just means the "step up" or where the two plains of the index ride to hold bits vertical will be much shorter on the machine length bits (or drills for you UK boys. )

Machine indexes will work for both (but may be top-heavy-FYI). Jobber length indexes are too tall for machine bits. They get lost in the abyss. BTDT.

 

[neophyte]

If you need a drill index for bits purchased at a hardware store you likely need one made for jobber length drill bits. Stub length drill bits tend to be very short and are generally made for drilling holes in thin material at most maybe an inch deep. Jobber length drill bits seem to be the standard length you find at hardware stores. There are also mechanics length drill bits which I believe tend to run about an inch shorter than jobber length drill bits, and tapper length drill bits which might run about an inch longer than jobber length. I believe Huot actually makes drill indexes for all the standard lengths. A 1/4" jobber drill bit runs about 4 inches so use that as a reference for what size bits you have. The length of the bits varies with diameter.

 

[jjjrmx5]

The length of a bit determines how long a hole can be drilled, and also determines the stiffness of the bit and accuracy of the resultant hole. Twist drill bits are available in standard lengths, referred to as Stub-length or Screw-Machine-length (short), the extremely common Jobber-length (medium), and Taper-length or Long-Series (long).

Mechanic's length is a non-descript length that does not fall into std. bit length protocal.

I've seen them the same length as jobber. I;ve seen them an inch longer or shorter.

All just a ploy to sell more bits. NOT something more useful, sadly.

 

[kythri]

Alright, cool, thanks.

So, my next question would be, what length would you assume these are:

http://www.harborfreight.com/115-piece-cobalt-drill-bit-set-47653.html
http://www.harborfreight.com/115-pi...d-m2-high-speed-steel-drill-bit-set-1611.html

Jobber?

I just recently acquired this:

http://www.harborfreight.com/16-speed-floor-drill-press-43389.html

For $80 off of Craigslist.

I didn't have any kind of comprehensive set of bits, and picked these up tonight at some deep discounts - 25% off coupon and some in-store sales stuff that was going on. Figured the cobalts would be for metal drilling stuffs, and the titanium-nitride for the rest of it.

I know that HF and other import drill bits take a lot of flack, but these are relatively cheap for what they are, and my thought process here was to have these, and then replace, as needed, with quality/better bits where it counts. I'm a big fan of not having to constantly run out for this or that, and liked the inexpensive comprehensive sets.

Anyhow, the flimsy sheet metal cases on these really aren't great, and I wanted to snag something heftier/sturdier before these ones open up all over my shop floor.

 

[neophyte]

Drill bits sets like that usually contain jobber length drill bits.

 

[jjjrmx5]

Alright, cool, thanks.

So, my next question would be, what length would you assume these are:

http://www.harborfreight.com/115-piece-cobalt-drill-bit-set-47653.html
http://www.harborfreight.com/115-pi...d-m2-high-speed-steel-drill-bit-set-1611.html

Jobber?

Yes. That is my bet.

I have yet to see HF carry long drill bits or short/machine length.
Everything I have seen is jobber length from them.

Machine length is usually sold to mfg floors and machine shops and long/taper length are usually used for specialty work like AF&PP, vehicle modification shops, construction contractors and other specialty applications.

HF bits are quite adequate for a weekend home shop.

One set for wood/plastics. One set for metal. Keep them sharp via a grinder/Drill Doctor and they will suit 95% of your home needs.

 

[the gypsy]

While we are on the subject of bits, may I ask you guys this. Is it worth it to buy a brand name, is there a difference in cutting ability with a brand name as compared to let's say HF?

 

[jjjrmx5]

While we are on the subject of bits, may I ask you guys this. Is it worth it to buy a brand name, is there a difference in cutting ability with a brand name as compared to let's say HF?

The big question is what are you going to be drilling?

For metal, yes. Quality ranks very high.
Wood and plastics are much softer thusly they are more forgiving and less stressful on a bit.

We get USA Dormer bits from our supplier and I am happy with them.
Norseman bits (can even get them from Epsteins) are at the top too.

That's why I keep two seperate sets . (Well more than 2 now LOLZ>)

118 degree or 135 split point for wood/plastic . Good 135 degree split point for metal.

I have a drill bit sharpener so no bits daunt me, but the HF set for wood, plastic, alum, and sheet metal normally are a good value. At least until they make them shittier.
Drilling plate steel, bolts or hardened metal with them can be less than fun.
Drill out spot welds and that is even higher on the **** scale.

It's another item where pro users vs. weekend-warriors make a fork in the road and the high/low $$$ choice is apparent.

For heavy users, bits (aka drills UK) are use and scrap items.
Buy. Use. Toss.

For metal work, good drill bits make life far easier and more porductive.
My $.02.

 

[kythri]

I have a drill bit sharpener so no bits daunt me, but the HF set for wood, plastic, alum, and sheet metal normally are a good value. At least until they make them shittier.
Drilling plate steel, bolts or hardened metal with them can be less than fun.
Drill out spot welds and that is even higher on the **** scale.

It's another item where pro users vs. weekend-warriors make a fork in the road and the high/low $$$ choice is apparent.

Just out of curiosity, how does that apply to the two different bit types - cobalt vs. titanium nitride? Am I off base thinking that the cobalt bits are better for metal?

 

[larry_g]

I would not spend a dime for Ti coated bits. They are for production use. The Ti coating on a good bit gives a bit longer life when being used for repeated use like in a CNC manufacturing situation. A lot of the cheaper coated bits are just a cheap bit with coating. A bit like polishing a turd. Cobalt bits are for harder metals so if your doing that then spend the money. Me personally I just use good HSS bits for most stuff. If necessary I'll get a cobalt or carbide bit to do the job.

lg
no neat sig line

 

[Mr. T]

For what it's worth, I have a set of cheapy HF Ti bits and the coating is worthless. That and if you get them within eye shot of metal they need to be sharpened. Great for wood/plastic though.

 

[justanengineer]

I concur with jjjmrx5 in that MOST hobbyists can get away with cheap drills for wood, plastics, etc. However, if they start drilling anything in a critical piece of metal I would highly suggest taking the time to find/purchase a GOOD QUALITY drill as removing broken drills stuck down in a hole can be extremely difficult at times.

 

[skruft]

I think the best place to get twist drills (the extra-correct name for these) to start out is at flea markets. Sets of good HSS drills are easy to find for $10 or so. Then when they are dull, sharpen them or have them sharpened. I believe, never buy new drills except the small sizes that break.

 

[Ign]

I've got several parts I make where I don't want to spot drill/center drill prior to, well, drilling. I use 135 degree screw machine bits because they're much less likely to walk.

If you do any metalworking more than twice a year invest in good bits, I've become loyal to Precision Twist (PTD) thru good results.

 

[fredybender]

General rule of thumb on sub & jobber length:
Jobber: Ratio of about 4-5:1 on diameter to cutting length
So a 1/4'' drill would have approximately 1" to 1-1/4" cutting length

Stub: usual 2-3 X D
so 1/4" would have 1/2" or so cutting length.

The stubs usually come in at 135 deg split point.

The shorter the drill, gives best results on hole tolerance, finish, and drill will not flex as much when feed force is applied.
Run out is also directly related to length;
In a machine application a 1/4" drill with 0.002" run out, will give you about 50% less tool life. If using carbide instead of HSS, that number drops to about 20% of the tool life expected...

 

[0.511MeV]

While we are on the subject of bits, may I ask you guys this. Is it worth it to buy a brand name, is there a difference in cutting ability with a brand name as compared to let's say HF?

I would say yes there is a difference. Even in a 12 pack of the same size drills from the same company, probably the same production run, on the smaller sizes (tiny wire gauge sizes) I've noticed that 1 of those drills sometimes will not cut the same as the others. And I only buy decent brands of drills if I need a 12 pack. So if a good brand has a that kind of QC, how do you think the QC is for a crappy brand?