best drill bit for hand drilling larger holes and enlarging existing holes - Page 2
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  1. #21
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    See! Reamers.



    Quote Originally Posted by sfriedberg View Post
    Bridge, car or construction reamers. Can easily take off 1/8" on diameter, more if you've got a good rigid drilling setup (which is not how they are normally used).

  2. #22
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    Quote Originally Posted by ericfox View Post
    Hey guys,

    Here at our plant we have some silver deming bits - made in the USA cobalt bits. We don't use them a lot - but today was one of the times we needed them.

    One of our employees had to enlarge some 3/8" holes to 7/8" holes. The material was about 3/16" carbon steel. He did this by stepping up bit sizes one at a time. He said all our bits were dull and no good. I look at the bits and all seem sharp - each had a minor damage to the very outside tip of the cutting edge - so maybe that will kill the effectiveness of the bit.

    I have read on here that some people say stepping is not necessary and deming bits will not step good - then other people say they have been doing it for 30 years with no issue

    Later I tried drilling one of the holes personally going from the 3/8" straight to the 7/8" size. We were using a heavy duty Milwaukee cordless drill. It worked pretty good until we got about half way to three quarters through the thickness and then it slowed down big time. We made it through but it took another 3-4 minutes to make it the rest of the way.

    Is there a better way to enlarge holes like this? maybe a different type of bit? still needs done with a hand drill though if possible since we can't use our mag drill on everything - like in this case

    Thanks! Eric
    OK, am I the only one finding this ironic? "We" chased a guy off recently for using a home built (whatever hobby grade) cnc trying to machine a part, and here we have 2 pages going about helping a guy 'enlarge' a hole with a hand drill? ---

    3/16" carbon steel... OK, what kind?

    since we can't use our mag drill ... OK, no drill press, bridgeport, nothing else available? (this is a professional forum after all... )

    Whatever I guess.... lots of people complaining about the site going down hill. This^^^^^ seems like the perfect example to have a "hobby" sub, but that went over like a turd in a punchbowl so I am not sure what guys here are looking for....

  3. #23
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    The tapered reamers work pretty well in truck frames, so hard they dull regular drills. Not every job can be set up in a machine, and not everyone who wants to do such jobs is a hobby shop guy. The constant personal attacks are why I dont read some parts of this forum. Everyone from time to time needs some kind of help or information. Its nice to be able to reach out and find the help you need. Tough to have a job beating you up, and no where to turn. Just sayin.

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    Quote Originally Posted by Mike1974 View Post
    OK, am I the only one finding this ironic? "We" chased a guy off recently for using a home built (whatever hobby grade) cnc trying to machine a part, and here we have 2 pages going about helping a guy 'enlarge' a hole with a hand drill? ---

    3/16" carbon steel... OK, what kind?

    since we can't use our mag drill ... OK, no drill press, bridgeport, nothing else available? (this is a professional forum after all... )

    Whatever I guess.... lots of people complaining about the site going down hill. This^^^^^ seems like the perfect example to have a "hobby" sub, but that went over like a turd in a punchbowl so I am not sure what guys here are looking for....
    Just my $0.02, but ...

    Given that professionals on this site span from those who can machine intricate micro-precision parts, to those who fab multi-ton machinery, to everything in between, I can easily imagine that a professional shop might find itself in the situation described by the OP.

    What I find much, much less likely is that a hobby shop has a mag drill at all, much less a mag drill but no other tooling.

    And what I find pretty near impossible to imagine is that a hobby machinist has employees ... !

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  7. #25
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    Quote Originally Posted by ericfox View Post

    One of our employees had to enlarge some 3/8" holes to 7/8" holes. The material was about 3/16" carbon steel. He did this by stepping up bit sizes one at a time. He said all our bits were dull and no good. I look at the bits and all seem sharp - each had a minor damage to the very outside tip of the cutting edge - so maybe that will kill the effectiveness of the bit.
    During the process with a hand drill how do you keep the hole from getting that triangle shaped pattern?

    I have done stepping like that with a drill press and had not much choice in speeds. The slowest speed on a Rockwell 6 speed drill press was not slow enough. The material was only 1/8 thick carbon steel. The 1" bit got slightly damaged on the outside tips. Drilling on a mill is so much better.

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    Getting a Mag drill to hold on 3/16” Steel is going to be problematic, at least from my experience.

    Can I have the old Deming drills? I have a bench grinder... :-)

  9. #27
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    Quote Originally Posted by ericfox View Post
    Hey guys,

    We were using a heavy duty Milwaukee cordless drill. It worked pretty good until we got about half way to three quarters through the thickness and then it slowed down big time. We made it through but it took another 3-4 minutes to make it the rest of the way.

    Thanks! Eric
    My guess is that portable drill was running at full speed and producing dark blue chips. It is very easy to work-harden material running a large bit at high speed. Try using a lower speed and a heavy enough force on the drill to make decent sized chips that are no darker than straw color.

  10. #28
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    We do have a prohibition against discussing "hand" tools. I take that to mean things like repairing a hammer or sharpening a hand saw or perhaps even repairing an electric hand drill. That is, discussion of the tool itself, not discussion that involves USING a hand tool. Professionals use hammers, screwdrivers, pliers, and hand drills.

    It is nice to have expensive, "professional" tools to do everything, but there are things where those professional tools are not the most appropriate choice. For instance, lets say that a PROFESSIONAL shop needs to drill a hole in the side of a 300 foot ship with aluminum exterior plating. What does a PROFESSIONAL shop do? The ship would not even fit in the shop door, much less on the table of a drill press or mill. I don't know about your foreman, but I would hand the employee a hand drill, battery or line powered, and tell him to hang off the side of the ship or climb a ladder or scoffold on the dock and drill the hole with that HAND drill. I worked in TV and I assure you I was a professional in a professional environment. On several occasions I had to drill holes in tall TV towers, once at about 450 feet above ground level. And, the members to be drilled were small angles and they had heavy coats of paint on them, so a mag drill probably would have been problematic. Yes, that tower could have been taken down and only the sections that were to be drilled could have been brought into a large shop. That way, those holes could have cost hundreds of thousands of dollars to drill and the job would have taken weeks. AND the TV station would have lost millions of dollars due to lost air time. I used a HAND drill: that choice was so obvious that there was NO debate on that in my mind nor in anyone else's. The job only cost hundreds of dollars, mostly for my time, and was completed in a single afternoon WITH NO INTERRUPTION TO THE USE OF THE TOWER. And I will defend it as a completely PROFESSIONAL method.

    I am sorry, but "professional" is not defined by the machines used. Nor is it defined by "machine" tools vs. "hand" tools. Professional is what professionals DO when confronted with a job that has to be done.

    I am not arguing against the board's rules. I understand the need for them and I support that. It is just that it is not possible to cover every situation with a few words in a statement of what is permitted and what is not. I personally think this is a good discussion for this board and apparently our moderator must agree as this thread has not been shut down.



    Quote Originally Posted by Mike1974 View Post
    OK, am I the only one finding this ironic? "We" chased a guy off recently for using a home built (whatever hobby grade) cnc trying to machine a part, and here we have 2 pages going about helping a guy 'enlarge' a hole with a hand drill? ---

    3/16" carbon steel... OK, what kind?

    since we can't use our mag drill ... OK, no drill press, bridgeport, nothing else available? (this is a professional forum after all... )

    Whatever I guess.... lots of people complaining about the site going down hill. This^^^^^ seems like the perfect example to have a "hobby" sub, but that went over like a turd in a punchbowl so I am not sure what guys here are looking for....

  11. #29
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    Nicely worded EPA! You never know what you need till you get there, & there’s the other thing, WTF do you do if a bridge is 300’ over water??? You can’t carry it to the shop.

    We used to call them core drills (google foo seems to suck on this???)… A small set to 3/4” attached (no.. not horrible freight, likely unobtainium these days). A 1980’s era holeshooter works well up to 3/4”. Never tried them with 3/16” thick but 1/4”+ they're good to go...

    Good luck, Matt
    Attached Thumbnails Attached Thumbnails core_drill1.jpg   core_drill2.jpg  

  12. #30
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    I have also heard “dreamers” as a term for those.


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