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I have a similar set, don’t use them much but it’s good to have them. I also have a set of left hand drill bits in the arsenal.
 

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I have a similar set, don’t use them much but it’s good to have them. I also have a set of left hand drill bits in the arsenal.
Do they fill the hole back in? Must be hard to push the chips back down the spinning flutes.:laugh:

Sorry couldn’t resist.:hide:
 

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I work as a millwright, very seldom do we use metric drill bits. We just use standard bits for metric holes. With a set of letter, number, and fractional bits you have a bit that’s very close to a metric bit.
 

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Having worked in and ran machine shops for a career, drills and how they were used was one of my pet peeves.

The kinds of work we did with precision location, size, and shape of holes was critical at times. We used metric drill a lot depending on hole tolerance and material being drilled. Metric drills many time made a difference in these specifications.

We used a lot of index-able insert drills, too expensive for occasional home shop use.

For most production jobs with small holes that we did I would order North American made twist drills because depending on material and other conditions I could depend on the number of holes per drill and number of resharpening each drill would produce. Even with a more expensive drill this would keep the cost per hole to a minimum.

My problem was many times some bean counter or other person wanting to be a monthly cash sheet hero would substitute cheap Chinese drills that were not dependable, would not last, and created scrap parts when they failed. It was hard to get the cost per hole idea through there head.
 

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I have a similar set, don’t use them much but it’s good to have them. I also have a set of left hand drill bits in the arsenal.
Kenny,
Can you name a time when a left-hand drill bit would be needed? Just curious....

Sincerely
 

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Drilling out sheared bolts... the friction is usually enough to twist our the bolt without screwing the threads (no pun intended):laugh:
 

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Kenny,
Can you name a time when a left-hand drill bit would be needed? Just curious....

Sincerely
What John wrote below is correct. For me, 50% of the time a broken bolt will turn out of the hole when drilling. If it doesn't come out, them you have a hole to use THESE or THESE. The twisted style "easy outs" are pure evil, evil I say:laugh:

Drilling out sheared bolts... the friction is usually enough to twist our the bolt without screwing the threads (no pun intended):laugh:
 

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What John wrote below is correct. For me, 50% of the time a broken bolt will turn out of the hole when drilling. If it doesn't come out, them you have a hole to use THESE or THESE. The twisted style "easy outs" are pure evil, evil I say:laugh:
I have always used high quality twist-style EZ-Outs with great success. Amazon.com: IRWIN Tools Hanson Spiral Extractor and Drill Bit Set, 10 Piece, 11119: Home Improvement Never had a need for a L/H twist drill, although I do understand how it could help extract a broken bolt. Any other applications aside from that?

Sincerely
 

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I have always used high quality twist-style EZ-Outs with great success. Amazon.com: IRWIN Tools Hanson Spiral Extractor and Drill Bit Set, 10 Piece, 11119: Home Improvement Never had a need for a L/H twist drill, although I do understand how it could help extract a broken bolt. Any other applications aside from that?

Sincerely
The square ones are much stronger Joe, that’s just a fact. Good to hear you’ve had good luck with the twisted one, many cannot say the same.
Extracting bolts has been my only use for LH bits.
 

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If you're tapping a hole that's going to have left handed threads, the hole must be drilled with a L/H twist drill bit.



:hide:
Honestly didn't know left handed bits were a thing until seeing this thread... figured it was an old contractor's joke like a left handed hammer or left handed duct tape. :dunno:
 

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I have always used high quality twist-style EZ-Outs with great success. Amazon.com: IRWIN Tools Hanson Spiral Extractor and Drill Bit Set, 10 Piece, 11119: Home Improvement Never had a need for a L/H twist drill, although I do understand how it could help extract a broken bolt. Any other applications aside from that?

Sincerely
Removing broken bolts and screws are my only use for LH bit too. Did you notice the IRWIN set you linked to has LH drill bits? :laugh:

My experience with the spiral extractors has been where they start to dig in, the spiral expands against what's left of the bolt's wall and makes the stuck bolt tighter. Keep on turning and it keeps expanding the broken bolt. If I had started with a smaller spiral bit, I usually end up breaking it in the broken bolt or there isn't enough meat that the extractor just spins. Can't win either way.

BTW, isn't it a sinking feeling just before the extractor breaks inside the bolt? :flag_of_truce:

Just my 2 cents.
 

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Hi All
The best extractors I have used are Rigid Model 10 screw extractors. They are a parallel spline that is driven into the hole, they are not as brittle as most other easy outs, they start to deform before breaking giving a bit of warning. They don't spread the broken bolt like twisted type easy- outs and they have more contact area than tapered ones.:good2:
Regards John
 

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Removing broken bolts and screws are my only use for LH bit too. Did you notice the IRWIN set you linked to has LH drill bits? :laugh:
I did not!!! I shared the link primarily to show the twisted screw extractors.... That's too funny....!!!:lolol:

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I can add to the left handed drill discussion.
In some old school high production turning equipment (ACME Automatic Screw Machine) a near finished part is picked up from a turning spindle and gripped in a pick off collet and the part can be "back finished" on the end that was cut off from a solid bar. The tools that engage the part in the back finish collet must be left hand cutting.

Also, as to metric, we often need to produce holes in parts that must either be drilled to an exact size or drilled slightly under a exact size and then finished to exact size by other, more accurate means. We use as many metrics as imperials in our shop.


IMG_5233.JPG

Here is a pic of a 6 spindle acme. Oh what a joy to set up and run...
The pick off position is unfortunately on the other side of the machine but this is the cleanest pic I could find in a minute to kind of show you guys the deal.
This machine can produce turned parts with multi features as fast as maybe 400 parts an hour with the right material. It's how we won the big one (war)!
 

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I can add to the left handed drill discussion.
In some old school high production turning equipment (ACME Automatic Screw Machine) a near finished part is picked up from a turning spindle and gripped in a pick off collet and the part can be "back finished" on the end that was cut off from a solid bar. The tools that engage the part in the back finish collet must be left hand cutting.

Also, as to metric, we often need to produce holes in parts that must either be drilled to an exact size or drilled slightly under a exact size and then finished to exact size by other, more accurate means. We use as many metrics as imperials in our shop.


View attachment 662900

Here is a pic of a 6 spindle acme. Oh what a joy to set up and run...
The pick off position is unfortunately on the other side of the machine but this is the cleanest pic I could find in a minute to kind of show you guys the deal.
This machine can produce turned parts with multi features as fast as maybe 400 parts an hour with the right material. It's how we won the big one (war)!

I will bet the guy who runs that has grey hair. Now that I think of it some of it from that machine.:laugh:
 

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I prefer to weld a nut on top of the broken bolt and back it out.

It is simple and no chance to hit threads.

can not always use it but it is effective.
 
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