Drilling holes in cast iron with portable drill

[James Baker SD]

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

[Jerome Hanby]

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 :)

[Greg R Bradley]

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?

[Steve Leverich]

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-Attachment-4-Inch-8-Inch-Drills/dp/B000JCIMEA/ref=pd_cp_hi_0?pf_rd_p=413863601&pf_rd_s=center-41&pf_rd_t=201&pf_rd_i=B0000E6TM6&pf_rd_m=ATVPDKIKX0DER&pf_rd_r=1XRPSP79Y8NQ2BASP0VS

HTH... Steve

[Chip Lindley]

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!

[Ryan Hellmer]

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

[David Cefai]

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_generated/en/products/product_groups/857_product.html

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

[James Baker SD]

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.

[Thomas Delpizzo]

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.

[Ben Abate]

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.

[Callan Campbell]

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:p:p:p
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:D:D:D

[george wilson]

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

[Mike Henderson]

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

[Jason White]

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



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

[Scott T Smith]

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.

[george wilson]

Cast iron is used for machinery because,as said,it is self lubricating. I am an experienced long time machinist,and know it is cut or drilled dry.

There was a company years ago which tried making large jointers with steel tables. They got grooves in them soon,and the practice was abandoned. It was Oliver,I think.

[Norman Hitt]

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 on the top of the hold 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.

+1 on "everything" you said. One thing NOT mentioned here is that when bit starts out the back side, you need to ease off on the pressure but keep a good grip on the drill, because the bit will try to grab the remaining bit of metal and run on through (like a bolt in a threaded nut) and this will many times cause a chip/chunk to break out on the backside. You can also prevent this if you have room to clamp a piece of hardwood on the backside the same as you would when drilling through wood to prevent tearout on the backside of the hole. (and yes, drill it dry)

[Rich Engelhardt]

Cast iron is used for machinery because,as said,it is self lubricating. I am an experienced long time machinist,and know it is cut or drilled dry
Ok - that's good info & worth every bit of the six bucks I paid to be here. ;)

Next logical question would be - do you tap cast iron dry also or use a lube?0
(I know Scott mentioned it - but - I'd like to hear what George says - (he's a grumpy old fart just like me ;) & we think alike - just kidding ;) )

Using a countersink on the top of the hold before tapping is a good idea.


? I'm not real clear on what that means?
Slightly bevel the hole with a countersink?

FWIW - I'm just getting ready to drill/tap my CI table saw top so I can put a mount on it for an outfeed.

[Scott T Smith]

Ok - that's good info & worth every bit of the six bucks I paid to be here. ;)

Next logical question would be - do you tap cast iron dry also or use a lube?0
(I know Scott mentioned it - but - I'd like to hear what George says - (he's a grumpy old fart just like me ;) & we think alike - just kidding ;) )


? I'm not real clear on what that means?
Slightly bevel the hole with a countersink?

FWIW - I'm just getting ready to drill/tap my CI table saw top so I can put a mount on it for an outfeed.

Sorry Rich, I had a typo. You're interpretation is correct - slightly bevel the hole with a countersink.

No offense taken re asking George's opinion - I pay a lot of attention to his thoughts as well.

[Chip Lindley]

Aside from personal experience, I take my advice to drill CI dry, from The New American Machinist's Handbook (1955). Basic machining principles have changed little for those of us using HSS tooling in older machinery in a home shop.

Drilling CI creates powder instead of a curling chip. Dulling of bits is hastened by the slurry created by oil as a lubricant. Dry drilling allows the iron particles to be lifted by the drill flutes. Frequently blowing out the bore with compressed air is advised.

No doubt in commercial settings, there might be a trade-off between production speed, and bit sharpness with the use of a lubricant as coolant. But, carbide tooling is utilized there also.

[george wilson]

To avoid your drill grabbing when coming through the other side of cast iron,plexiglass,or brass,grind a vertical flat on each cutting edge of the drill bit. It will have a scraping action and will not get sucked out of the opposite side and crack the plastic or cast iron. Nor will it get sucked out the other side of brass and break your wrist by the drill suddenly twisting.

I had to drill some 3/4" holes through some brass with a powerful hand drill. The first hole nearly got my wrist before I could let go of the trigger. The drill was geared down to 850 RPM,and was very powerful. After that,I ground my bit
thus,and had no further problem.

Some guys were operating a hi-fi shop,and made a speaker enclosure from plexiglass which was very expensive. They said they kept breaking a lot of plexiglass drilling through it. I showed them how to sharpen their drill bit,and they were then able to make the cabinets cheaper,and perhaps sell some!! I didn't think a clear plastic enclosure showing the speakers and all the wires was attractive,personally.

It is good to drill a pilot hole the size of the drill's web first. The web doesn't cut well,and pushing the web through by hand is work.

[Rich Engelhardt]

grind a vertical flat on each cutting edge of the drill bit.

George,
You lost me there.:confused:

I'm not sure what that refers to?

Also - should I tap lubed or dry?

[george wilson]

On the front edges of the drill bit where the cutting action takes place,grind the cutting edges vertical to the axis of the drill,so the drill has a scraping action rather than a cutting action. They used to make drills for brass. Their flutes ran straight up the drill bit rather than spiraling. Their cutting edges,or lips,were therefore vertical. They looked like the straight fluted bits found in the wooden handles of old eggbeater drills,except the brass drills were made of HSS. You can simulate their cutting action by grinding the cutting edges vertical,even for only 1/32" it keeps the drill from grabbing when it breaks through.

[Rich Engelhardt]

Gotcha!
Thanks!

(just kdding about the GOF - you Da Man George)

[Phil Thien]

What works really well for this, BTW, is those portable drill presses with magnetic bases that mechanical contractors use for drilling holes in i-beams, etc. They're very expensive, but man they're neat.

Back in about 1986 (I was about 20-YO at the time) one of my jobs was to write code that controlled machines that polish nuclear fuel rods. They used these magnetic drill presses from time to time when upgrading/changing machinery. They had one where you could secure the base, and then very precisely align X/Y with little knobs. It was slicker than snot.