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Technical Shop Class Basics: How to Properly Drill a Hole in Metal

Discussion in 'The Hokey Ass Message Board' started by phartman, May 13, 2019.

  1. big duece
    Joined: Jul 28, 2008
    Posts: 5,435

    big duece
    Member
    from kansas

    Its very important to clamp your work piece down to avoid injury... drillpress.jpg
     
    j-jock, clem, Rich S. and 2 others like this.
  2. Always let the drill bit do it's job, being impatient and putting a lot of pressure on the drill only heats up the bit and dulls it faster, it also can cause the bit to wonder, go as fast as the bit wants to cut and keep it lubed.
     
    flatford39 likes this.
  3. 55Belairretrorod
    Joined: May 2, 2013
    Posts: 65

    55Belairretrorod
    Member
    from Australia

    Was taught by my dad (qualified fitter/turner and machine shop teacher) to use kerosene for lube when drilling aluminum.
     
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  4. Als27T
    Joined: Jun 2, 2010
    Posts: 41

    Als27T
    Member

    You can also consider water soluble coolant. You purchase concentrate and mix it with water - ratios of 5 to 1 to 10 to 1 (water to concentrate) in a hand spray bottle. Water is an excellent medium for the transfer of heat - the enemy of cutting tools. You'll note when you spray the coolant on a drill the water vapor (not steam) be created by the heat of the shearing of the metal by the cutting tool. That heat went into separating the water from the concentrate. What little concentrate whirls around in all the cutting action. When you're finished machining you may want to wipe any coolant that didn't get consumed in the machining. Here's an example of a water soluble coolant (concentrate) - not a particular product recommendation.

    Anchorlube G-771, 8 oz Bottle Cutting Fluid
    - Water Soluble, For Broaching, Counterboring, Drawing, Drilling, Engraving, Fly-Cutting, Hole Extruding, Milling, Piercing, Punching, Sawing, Seat Forming, Spot Facing, Tapping
    https://www.mscdirect.com/product/details/00063909
    https://www.anchorlube.com/anchorlube.html
    "Water soluble fluids blend oil with emulsifiers and additives to create an oil-based coolant to be diluted with water. These fluids provide excellent lubricity and an increased cooling ability over straight oils."
     
  5. atch
    Joined: Sep 3, 2002
    Posts: 4,194

    atch
    Member



    Yes. Be sure to wipe everything down every time you use this. A friend bought a horizontal bandsaw several years ago. It was "rated" for water soluble coolant and had the built in pump and coolant storage tank. Unfortunately, after 3-4 years the metal in the coolant troughs rusted through so badly he quit using that bandsaw and bought a new one.
     
  6. gimpyshotrods
    Joined: May 20, 2009
    Posts: 15,938

    gimpyshotrods
    Member

    We use these in the R&D shop, for sheet metal:
    [​IMG]

    Away from a machine, step bits.

    For drilling aluminum, when it cannot be put in a machine, we use undiluted fluid from the CNC mill. For stainless, we use Elmer's white glue. For steel, Tap Magic.
     
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  7. We had a local shop, people still talk about this one that happened around 1976, my brother worked down the street in another shop at the time. This was an R&D shop, still is. Someone was turning a large part on a big gap-bed engine lathe. Deep down in back-gears, like 34 RPMs... his shop coat tail got caught in the lead screw. Nobody was around when it happened, safety-101 was not being employed, avoid working alone in machine shops! The lathe didn't even skip a beat. The guy was pulled in and wrapped around the face plate, probably dead in seconds. When someone came in, pieces of the guy & coat were still spinning.
     
  8. We had the best drill sharpener in the world at work, I'll have to see if I can dig up the name, something like Blackhawk.. found it, Black Diamond! That would do 1/8" easy, but tough to get a good sharpen out of anything smaller. When I buy small drills, I always get a package of 12. For work on the Bridgeport, I like screw machine drills. The TiN coated ones hold up well and are only a few cents more per.

    This is a good formula that will keep you from smoking up drill bits.
    RPM = (CS X 4)/D.
    Cutting speed you can look up, mild steel is 100, aluminums are 300 and up. The 4 is a constant, D is the drill or cutter diameter.
     
    Last edited: Jun 14, 2019
  9. I keep a few cutting oils around. Water soluble, Hangstefers (sp?) has one with a 50:1 mix ratio, a little goes a long way. Anchor Lube is also good on stainless steel, the green stuff can be thinned with water. Very good on titanium. Mold Dee (made now by Castrol) for tough steels. There is one for aluminum, Alumatap, said to be kerosene (Klansman Cologne..) based. I got a can of Tap Matic fluid, works well with their tapping heads. Plain old WD40 or 3 in 1 oil is good in a pinch, so is MMO.
     
    Last edited: Jun 14, 2019
    gimpyshotrods likes this.
  10. ekimneirbo
    Joined: Apr 29, 2017
    Posts: 134

    ekimneirbo
    Member
    from Brooks Ky

    Its really pretty much just common sense what you need to do. When drilling you need to be able to get the cutting edge of the drill to shave a chip rather than just rub and work harden the metal. If drilling large holes, you slow the bit down, and smaller holes you speed up...somewhat. Most drills are dulled because the person doing the drilling runs the hand drill or drill press too fast. Especially hand drills are usually held full throttle when drilling.

    Pressure is also important. A lathe/drill press/milling machine will have a mechanical advantage that allows the machinist to exert far more pressure than a hand drill applies. The ease of applying this pressure with the mechanical advantage fools people into thinking they aren't applying much pressure. You usually get notified quickly when too much pressure is applied. On the other hand, too much speed or too little pressure rubs , and doesn't allow the cutting edge to slice a chip. It fools you and you increase speed and make it worse. The drill seems to quit drilling because the workpiece has hardened. Then you try a new drill and it quickly dulls too.

    Not saying you can't apply too much pressure, but usually the culprit starts with too much drill speed. Try drilling holes at about half the speed you normally do and see if results are not more satisfactory.

    You can write a book on cutting oils and coolant. In production shops, high speed feeds and continuous cuts generate heat. The water based coolant helps keep the heat down in the part and the tool. It is seldom needed in a home builders shop. Oil of any kind usually helps, but you seldom find a place to use it when drilling on your car. It is handy for tapping holes and reaming and drilling something restrained in a machine.Use of virtually any non-flammable liquid usually helps. I wouldn't get caught up in any one type of oil being particularly better than another in any situation other than production machining. When I tap threads, I usually squirt a little WD-40 on the hole and tap.
    Not because its the best, but it does what I need, its easy to wipe up, doesn't create a big mess, and I'm lazy.

    Edit Note: The rpm range you use for drilling will be faster when drilling aluminum than the rpm range you use for drilling steel. Stainless usully mimics regular steel but generally requires more pressure to cut a chip.

    Look at some of your drill bits. See if they all have the same tip angle ground on them. The web in the middle of large drills often creates a problem because it pushes against the surface rather than cuts and resists your attempt to drill. Thats one reason you drill pilot holes before using the larger drill sizes.
     
    Last edited: Jun 15, 2019
  11. ekimneirbo
    Joined: Apr 29, 2017
    Posts: 134

    ekimneirbo
    Member
    from Brooks Ky

    We used to have to watch training videos showing us not to wear loose clothing, especially a tie when operating any machine, but especially lathes. Then when the oil/gas shortage hit, they turned the heat down in the manufacturing buildings and everyone had to wear coats and gloves. Then summer came and they cut the ends off the water cooler cords......but kept the A/C working in their offices. Never saw a machinist that wore a tie to work...only engineers.
     
  12. DDDenny
    Joined: Feb 6, 2015
    Posts: 11,455

    DDDenny
    Member
    from oregon

    Not saying some engineers aren't capable of doing machine work but we had an unspoken rule about our engineers using equipment, don't let them.
     
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  13. gimpyshotrods
    Joined: May 20, 2009
    Posts: 15,938

    gimpyshotrods
    Member

    I'm an engineer.
     
  14. DDDenny
    Joined: Feb 6, 2015
    Posts: 11,455

    DDDenny
    Member
    from oregon

    I do know that, and I'm pretty sure I understand your broad range of capabilities.
    You were the first person to come to mind here, precisely why I worded my post so diplomatically.
    To be clear, we had some very capable engineers, we had some that had to hire out having their shoes tied too.
    We even had one where it was common knowledge that we check any work he did after lunch as his lunch did not consist of "food", if you catch my drift.
     
  15. gimpyshotrods
    Joined: May 20, 2009
    Posts: 15,938

    gimpyshotrods
    Member

    You are correct, though, and, very sadly, everyone is called an engineer these days.

    I have to deal, daily, with engineers that design things that cannot be built, and would accidentally kill themselves in a machine shop.

    Worse than that, I have to deal with self-important "software engineers".

    The way that I was raised is that engineers are responsible for designing things. Software is not a thing. It is the basic difference between a product, and a service. If you can drop it on your foot, it is a product (aka: thing). If you can't, it's a service.

    Without software, hardware is manual. Without hardware, software is fantasy.
     
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  16. As a shop foreman I had to deal with many types of engineers. The worst type were those fresh out of school. they thought their book training was sufficient to direct us how to do things. I used to tell them you went to school, now you are in the real world, and this is how it is really done. When I got my first job as an apprentice, the old timer toolmaker showed me how to sharpen drills. It wasn't that easy, but I eventually got to know how to do it. He also showed me how to sharpen drills for different materials. Later when I was employed as a set up man I learned how to sharpen drills to be used on some exotic metals. This was a great education that I am still able to use.
     

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