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Thread: Drilling holes in cast iron with portable drill

  1. #1
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    Drilling holes in cast iron with portable drill

    Is it possible to drill a fairly decent hole in cast iron with just a handheld portable drill?

    Think of mounting a power feeder on a shaper top or drilling new holes for adding a cast iron extension wing. I would do as much as possible on a drill press, but some pieces are just too awkward, too heavy, or too hard to get out of the machine they are a part of, to get them to the drill press.

    James

  2. #2
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    I would think you could use your drill press to drill a thick piece of wood for use as a guide with the hand drill. That's not a "just a hand drill" solution, but close

  3. #3
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    Cast Iron is easier to drill than mild steel. It is more abrasive and will wear the drill bit faster. Use coolant to keep the edge on the drill bit from failing.

    A typical medium duty 1/2" corded drill will drill 5/8-3/4" without strain.

    Just curious - won't the drill press move so that the base is under the equipment you are drilling?

  4. #4
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    If you're gonna do more than a few holes, or want to tap them, you may want to invest in this

    http://www.amazon.com/Wolfcraft-Atta...79Y8NQ2BASP0VS

    HTH... Steve

  5. #5
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    James, I did just that, to mount a PF on my old Moak shaper. I laid out the holes accurately, and used a center punch to mark them. A 1/4" hole was drilled with a Black & Decker "Bullet" bit, which has a self-centering point. Then I drilled progressively larger holes, until reaching finished diameter; 27/64". I tapped the table holes 1/2-13. Drill and Tap the holes dry; no lube for cast iron.

    Hang onto that drill! Lots of torque at work there. Enlarging the hole by only 1/32" each time will minimize the bit hanging up. Easy Does It!
    Necessisity is the Mother of Invention, But If it Ain't Broke don't Fix It !!

  6. #6
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    I did this just a year or so ago on my shaper. Drilled with a hand drill, tapped with a hand tap. Worked like a charm. In hindsight, my holes could have been a bit closer to vertical but it's not the end of the world. Do use some lubricant, both for drilling and tapping. The block guide is a great idea as well.

    Ryan

  7. #7
    It's always intriguing to see the differences beween American and European solutions.

    Our version of the Drill Guide referred to above looks like this:

    http://www.wolfcraft.de/jcatalog_gen...7_product.html

    It too is a Wolfcraft product. Do American drills have standard size necks?

  8. #8
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    Thanks

    All--thanks for the encouragement. I know what I will be doing this weekend now. Since I have seen cast iron crack and break when dropped, I was a bit afraid that a drill might chip out pieces of iron rather than removing small bits and I would end up with a very uneven, rough hole.

    Jerome--I like the idea of a template. I will do that.

    Chip--I will use plenty of drills. Why no lube?

    Greg--too many earthquakes here, so I bolted the DP to the floor. Some of the holes are in vertical surfaces also. Coolant is water? Lube?

    Steve--I inherited something very similar from my Dad, use it fairly often.

  9. #9
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    Ditto to all. I had to do it in hardened steel. I ended up starting with a smaller hole a graduating it to the size I needed. Don't forget to use a lot of oil to keep the bit cool.

  10. #10
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    I've did a few tops for power feeders. I used a large chunk of maple as a drill guide. I used a piece of 10 quarter maple, then I cleaned it up and squared it up. I made it long enough that I could get clamps on it. Before I started onto the cast iron top or plate I predrilled a hole at the drill press. This hole acted as my drill guide. Being of 10 quarter stock kept the drill bit very straight. As someone menitioned you should layout your points to be drilled and center punch them and then proceed to use the drill guide. Other than going to your local rental agent and renting a vertical drill such as a HOGAN type magnetic drill I believe you'll not do a good job without a drill guide. Free handing it will not be too accurate, and if you intend to drill and tap the holes it will not be accurate.

  11. #11
    Quote Originally Posted by James Baker SD View Post
    All--thanks for the encouragement. I know what I will be doing this weekend now. Since I have seen cast iron crack and break when dropped, I was a bit afraid that a drill might chip out pieces of iron rather than removing small bits and I would end up with a very uneven, rough hole.

    Jerome--I like the idea of a template. I will do that.

    Chip--I will use plenty of drills. Why no lube?

    Greg--too many earthquakes here, so I bolted the DP to the floor. Some of the holes are in vertical surfaces also. Coolant is water? Lube?

    Steve--I inherited something very similar from my Dad, use it fairly often.
    What Chip was referring to is that some types of cast iron are easier to drill and tap than others, something to do with the make-up of the casting material. Kerosene was an old stand-by drill bit lube for cast iron as it's slippery, thin, and not expensive. I've drilled cast iron that had so much sand and other particles that lube was the least of your worries. Other cast was so smooth and greasy that no lube was required.
    For our uses, just use WD-40 as a cheap substitute. It's thin, will give enough lube, and it's cheap
    You also may need to brush the chips off your taps with a used tooth brush as cast iron won't create curls of metal when being machined. If the holes are deep, a shot of compressed air with you wearing safety glasses and holding a rag over the hole, helps to clear out chips as well.
    Last tip, this is a good one. Once you've drilled the holes to their tap drill size and are ready to tap them, put a decent counter-sink bit in your hand drill, and cut a small chamfer at the holes you've just drilled. This will make it easier to start the tap by hand, and you end up with a much cleaner looking threaded hole when you're all done. It doesn't take much extra time, just kiss the holes with the counter-sink for a 1/32" to 1/16"wide chamfer.
    Nice trick for any threaded hole, but always looks sweet in cast iron IMO

  12. #12
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    CAST IRON IS DRILLED DRY. Has anyone noticed that a few of these posts said that??? It is correct.

  13. #13
    Quote Originally Posted by george wilson View Post
    CAST IRON IS DRILLED DRY. Has anyone noticed that a few of these posts said that??? It is correct.
    I've always been told the same thing. I believe the reason you drill cast iron dry is because it has a high carbon content and the carbon acts as a lubricant. I was told that using oil only causes the swarf to accumulate, while drilling dry allows the swarf to blow away.

    Personally, I've never had any problem drilling cast iron, even with a battery powered hand drill.

    Mike
    Go into the world and do well. But more importantly, go into the world and do good.

  14. #14
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    Piece of cake! Cast iron drills very easily with no lubrication needed

    Use a slow speed on your drill and metal-cutting drill bit. Make a dimple with a punch or nail first so the bit won't wander when starting the hole. Jason


    Quote Originally Posted by James Baker SD View Post
    Is it possible to drill a fairly decent hole in cast iron with just a handheld portable drill? Think of mounting a power feeder on a shaper top or drilling new holes for adding a cast iron extension wing. I would do as much as possible on a drill press, but some pieces are just too awkward, too heavy, or too hard to get out of the machine they are a part of, to get them to the drill press. James

  15. #15
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    As George stated (and ask any machinist), cast iron is typically drilled dry, as it is self lubricating. I used to own an automotive machine shop, and have drilled many holes in CI over the years.

    You do not need to step the hole in small sizes either. Simply drill a pilot hole, and then use the correct bit for the tap that you will be using. Using a countersink to bevel the top of the hole before tapping is a good idea.

    A cordless drill will work just fine. Use a sharp bit and keep good pressure on it when drilling. If you have access to a Hougan mag drill, then fine, but it's overkill (and not usually used to drill the small holes that you'll probably use to mount the feder).

    The exception to the rule is if the cast iron that you're drilling is of extremely poor quality, and has hunks of unmelted recycled material in it. Then, it's anybody's guess.

    Be sure to check the bottom side of the casting for ridges before you start to drill. If you catch the edge of one with your hole, it may cause your tap to break when you tap it.

    I've tapped CI both with, and w/o a tapping fluid. It seems to work fine either way, but usually I'll use a small amount of tap-magic as a precaution.

    When you are cutting threads in CI, your tap should cut smoothly and consistently. If/when you feel a sudden increase in backpressure on the tap, it's a good idea to stop, reverse the tap for about 1/2 turn, and then continue to tap the hole. This will relieve the excess pressure on the tap and in many instances prevent you from breaking the tap. It is especially critical to do when you're tapping small diameter holes (less than 1/4"), as it does not take much pressure to break the tap.
    Last edited by Scott T Smith; 08-28-2010 at 6:48 AM. Reason: fix typo and added clarity

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