I'm too stupid to drill a hole!

[Tanshanomi]

I'm trying to make two simple spacer plates out of ordinary 1/8" mild steel. I just need to drill a couple of 17mm holes and shape it a little with a grinder. Really, really, simple stuff. Well, here are my first three failed attempts:

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I ordered a couple of "precision" metric hole saws online that ended up being shipped directly from Hong Kong, which scared me a bit. I chucked one in the drill press and gave it a shot. The runout was terrible and since my drill press doesn't have a slow enough speed, it was worn dull before it got halfway through, even though I used a little 3-in-1 household oil to lube the teeth.

So, I tried again with my 14.4V hand drill, trying to keep the speed where it was making the biggest chips. By the time I was half-way through, the center hole was so egged out that it was ruined.

I asked a friend of mine what I was doing wrong, and he said, "just pay a shop to cut them with a waterjet." That's not the only right answer and certainly not the one I was looking for. I'm trying to build a bike from scratch, as an experiment [http://www.caferacer.net/forum/topic.asp?TOPIC_ID=20019. I THOUGHT I was pretty savvy in the garage. I've been riding and maintaining bikes for over 30 years, but my only previous exposure with any sort of really serious custom fabrication was many years ago, when I was putting myself through college at a bike shop, which gave me access to all sorts of tools and equipment and mechanic friends to help me. Doing stupid little stuff like this alone in my garage is turning out to be a whole lot more difficult than I expected. I know there are guys without lathes and milling machines who do this kind of stuff. Am I really this stupid, or do I just not have decent tools?

 

[Jagmandave]

1) You need a slower speed for your drill press.

2) Drill the 1/4" hole, then use a small piece of 1/4" rod to guide the saw, then it won't egg out.

You need a lot of steady pressure on the saw and slow speed to get a good clean hole, also I'm not sure 3 in 1 is the right oil to use, I'd use cutting oil.

 

[Primered Thunder]

Buy a good quality (not Chi-wanese) bi-metal hole saw. Go slow. Used motor oil is fine, as it is used more for lubricity than cooling.

 

[Tanshanomi]

1) You need a slower speed for your drill press.

So what you are saying is, I need a better drill press.

 

[alan camby]

You need a good quality cutting tool and the proper speed. My craftsman DP only goes down to 250 rpm and i can drill holes like yours with no problem.

I drilled 36 holes in this c channel that had a thickness of over 1/4" all with one carbide tipped hole saw. The holes are 1-1/4"

 

[toolchaser]

An Annular Cutter is your best friend for jobs like that...

 

[antinym]

like everyone else said. You need to go much slower. When I'm cutting metal I use a lot of lube. Too much maybe messy, but way better than too little. I even built a pseudo portable coolant system.

 

[zip95864]

I learned some stuff about drill speed here: http://store.curiousinventor.com/guides/drill_speed

 

[jrlp]

Rapid Tap is the best cutting fluid I've come across. I bought a small USA made piston oiler with a flexible nozzle, and use it on everything. I use it whether I'm sawing something with the portable bandsaw (especially SS), sawzall, drilling tapping holesawing.. It makes a huge difference. It's thick enough to not get flung everywhere and sticks rather well to both the cutting tip and the stock. For the parts you're trying to make, someone with a plasma can kick them out for you in a few minutes. Have them cut it a bit large and use a die grinder to clean the edges up.

 

[larry_g]

I notice a couple of things with the cutter you posted a picture of. The teeth seem to have a negative rake which is not good for what your doing. The second is that the od of the cutter straight with no relief for the cutter shank to not rub on the od of the hole your cutting. You need some clearance between the cutter and the hole being cut, both on the od and id of the cutter.
Take a file and see if you can cut, file the tool that you have destroyed. If you can then you have a tool that is not hardened which could be from the material it is made of or not heat treated correctly. I would suspect that is a wood cutting tool, but I'm not familiar with the geometry of wood cutting tools of that nature.

Also investigate the difference between cutting fluid and lubricating oil. Lubricating oil is designed to keep metal parts separated so they have no friction or wear. Cutting oil or fluid is of low shear strength and will allow the cutter to contact the material it is supposed to cut. In the big box store go to the plumbing section and get some light or heavy cutting oil and try it. There is some advise above that I would take with a grain of salt.

lg
no neat sig line

 

[Dick in Wisconsin]

You need a good quality cutting tool and the proper speed. My craftsman DP only goes down to 250 rpm and i can drill holes like yours with no problem.

I drilled 36 holes in this c channel that had a thickness of over 1/4" all with one carbide tipped hole saw. The holes are 1-1/4"

What did you use the finished C-Channel for?

 

[alan camby]

What did you use the finished C-Channel for?

Hydraulic press

 

[bad_idea]

I work in ship repair and have to routinely drill holes upwards of 4" with a hand drill through 1/2" steel.

Drill the 1/4" hole, then use a piece of 1/4 stock as a guide instead of the drill bit. The shaft from a phillips screwdriver will work with some cutting.

Bimetal holesaw is good enough, morse or lenox are good.

Slow speed and steady pressure.

Anchorlube is a great cutting paste, lot less messy.

No need to buy a new drill press, 400 rpms will get it done. Plenty of cutting paste or fluid and lift the handle routinely to clear the shavings. The biggest thing I have found that dulls the holesaw are the shavings from the cutting operation. Once the hole saw cuts below the depth of the teeth it slows down quite a bit. This is only an issue on metals thicker than say 1/4". If it is thicker plate I usually drill a relief hole right in the path of the hole saw.

Don't worry, I work with plenty of jackasses that can't use a holesaw. It takes a little getting use to and some finesse. If using an electric drill, be careful it doesn't take you for a ride! If it catches it will ****** hard! I prefer a air drill if I have to drill it by hand, they stall instead of spinning.

 

[Jack Olsen]

There's really no getting around the slow speed part. You can buy a low-RPM hand-held drill at Harbor Freight, even.

 

[Olafur]

Even at way to fast rpm a decent hole saw should last several holes - and many with good cutting fluid. These drills are probably junk.

A decent step drill should do the trick also.

 

[darkk]

Your first problem is those are not precision hole saws. Those are spot weld cutters and were never designed to cut a thru hole in metal of any thickness. They were designed to cut through thin sheet metal around a factory spot weld. We used them *a lot* in the body shop........

 

[Tanshanomi]

The lowest speed on my drill press is 620 RPM, so I'm definitely going to have to use my hand drill to get down to the 250-400 range. I'd actually thought about using a section of rod in the pilot hole. I might also back it with a thicker chunk of steel with a 1/4" hole.

 

[Tanshanomi]

Anybody know where I can find quality bimetal hole saws in metric sizes? In this particular case there's no need for exact tolerance, so an 11/16" will work, but I will eventually need to make some fairly precise 15mm and 19mm holes...or do holes that accurate, that big really need to be milled?

EDIT: found this on Ebay — anybody know if this will do what I want?

Blair Rotobroach Metric Hole Cutter Hole Saw Kit 11092

http://www.ebay.com/itm/190696469529

 

[Jack Burton]

If you have a drill press, I'm assuming you can chuck up to a 1/2". So why not buy an 11/16" bit with a 1/2" reduced shank? Beats the hell out of any sweet & sour hole saw.

EDIT: McMaster has 17mm bits with 1/2" shanks.

 

[larry_g]

Anybody know where I can find quality bimetal hole saws in metric sizes? In this particular case there's no need for exact tolerance, so an 11/16" will work, but I will eventually need to make some fairly precise 15mm and 19mm holes...or do holes that accurate, that big really need to be milled?

EDIT: found this on Ebay — anybody know if this will do what I want?

Blair Rotobroach Metric Hole Cutter Hole Saw Kit 11092

http://www.ebay.com/itm/190696469529

That looks to be what you need, other than it contain no 17mm cutter. You can get the 17mm here http://blairequipment.com/Kits/Cutter_Kits.html and also research the difference between the cutters you have and what you need.

lg
no neat sig line.

 

[bad_idea]

If you want precision, then a hole saw on a hand drill is not what you are looking for. Hole saws wobble some when used and hand drills compound the issue. If precision is an issue, I would send it to a machine shop. I don't think it is worth the money to invest in the equipment to achieve precision at home unless you are making a shitpot of them. For basic things I buy lenox hole saws from home depot.

 

[Provincial]

I have a Blair Rotobroach set in inch sizes up to 3/4" that I have used for thirty years. I only use it occasionaly, but it has held up very well. I always use a slow speed and plenty of lubricant. Since they are made from High Speed Steel, they can't stand too much RPM.

Most any good industrial supply store can sell you a bimetal hole saw blade. Starrett, and Lenox are very good ones. You will not be able to make a precision size hole with a hole saw, but you can rough one out a little undersize and have it bored to size. If the part is small enough to chuck in a lathe, it is often quicker to bore it that way.

 

[HeelSpur]

Think you can't drill a hole, I got distracted and grabbed a 1/2" concrete bit and started drilling on some angle iron. Didn't realize it until the bit started breaking apart.

 

[Tanshanomi]

Thanks for all the advice, guys. With the helpful instructions, I actually managed to use a hole saw (somewhat) successfully. Using a garden-variety bimetal hole saw from the local Ace hardware store and an aerosol can of Tri-Flow allowed me to drill through 3/8" mild steel plate two separate times, using my drill press's lowest speed of 620 RPM. It only took around 30-40 seconds to go through each plate.

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The debris around the upper edge of the hole is just rough bits of the paper template glued to the top of the metal plate.
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Unfortunately, the hole saw didn't run true at all. (the pattern of paint wear on the saw attests to that). I knew that before I started because it visibly wobbled on the arbor, but I went ahead and tried it to see what sort of hole size I'd end up with.

Roundness is remarkably good and both holes are similar, but the nominally 7/8" (.875) diameter ended up being 0.89" at the bottom of each hole and about 0.96 at the top, or about 2% to 10% over. That's pretty sloppy, even for welding fit-up (this will be welded onto a 7/8" steel tube).

I'm going to try again with a better-quality Lenox hole saw with a screw-in arbor, and undersize it by 1/16" from what I need. I'll report back on how that turns out.

 

[dayid]

Just curious - but I didn't notice where anyone else asked: What drill press were you using? Many you can swap pulley kits to get the lower-than-stock speeds.

 

[383 240z]

Do you have a dimensioned drawing of what you need? I could bore them to whatever size you want on my mill with the boring head. Keith

 

[Tanshanomi]

Just curious - but I didn't notice where anyone else asked: What drill press were you using? Many you can swap pulley kits to get the lower-than-stock speeds.

I doubt it. It's a Chinese-made 10" Craftsman I got for $130.

 

[Tanshanomi]

Do you have a dimensioned drawing of what you need? I could bore them to whatever size you want on my mill with the boring head. Keith

This is the drawing I am working. the outside shape is pretty arbitrary; I just need to locate a 12mm swingarm pivot 2.5" to the rear of a 7/8" (nom. OD) frame tube.

​

 

[A_Pmech]

Hole saws do not produce round or accurately sized holes, no matter the brand.

If you want an accurately sized hole use an annular cutter. On a weak and wobbly drill press you should still stay within about +.015 of nominal. Use proper cutting oil to keep the cutter working.

Don't buy cheap cutting tools from China either.

Your .480" to .485" hole should be reamed or bored.

Drill and ream the small holes and run a tight fitting pin though the holes. Then drill the large holes so both plates have the same hole pitch.

 

[383 240z]

What is the thickness? Im guessing hot roll steel?

 

[Tanshanomi]

What is the thickness? Im guessing hot roll steel?

3/8", which is probably thicker than I need, but I figured it's better to overbuild than under-build. Now that I've made all my calculations based on that thickness, I'll stick with it, but there's nothing terribly precise about it—so yea, hot rolled would be fine. The piece I started with was a 4"x5" chunk of out of the by-the-pound odd scrap bin at the local metal shop, and I am fairly certain it's hot-rolled.

 

[383 240z]

If your not in a hurry I'll cut you a pair of them, I think I have some of that stock here in my shop.

I'm in the middle of an engine swap right now.Keith

 

[Tanshanomi]

If your not in a hurry I'll cut you a pair of them, I think I have some of that stock here in my shop.

I'm in the middle of an engine swap right now.Keith

That would be fantastic! And there is certainly no rush — I started collecting parts for this bike last October, and I'm just now cutting metal.

 

[383 240z]

What is the tolerance? Keith

 

[Tanshanomi]

What is the tolerance? Keith

Would ±0.01" be too much to ask? I could go ±0.02-0.03 without much issue. After all, it's not as if we're talking internal engine parts here. But less slop would be nice to help facilitate accurate alignment during fit-up and welding.

Here's a mock-up using my crappy hole-sawed plates, showing how they'll be used. I tinted them to make them more obvious.

By the way, the globby welds on the swingarm aren't mine — that's genuine production Yamaha weld quality, circa 1976.
​

 

[Tanshanomi]

I thought I should follow up and show you the successful completion of my original attempt, thanks to a nice quality Lenox bimetal hole saw and some cutting oil. My drill press's 620 RPM lowest speed worked fine.

Once I got the holes drilled, I finished shaping them with a hack saw, a couple of files, and a dremel tool.

Thanks to all who gave me much-need advice!

 

[383 240z]

My old machine can hold 0.005" The operator however might be another story. I should be able to free up some machine time here late next week. Keith

 

[Tanshanomi]

My old machine can hold 0.005" The operator however might be another story. I should be able to free up some machine time here late next week. Keith

That would be very cool. Send me a private message with what I owe you and your contact info; I'll send you a check or paypal you (whatever's easier).

 

[e-tek]

Glad top see you got 'er done!! Although no-one had said it exactly, but those look like spot-weld cutters to me. Someone mentioned the negative rake, which is what they have. You could also have done it with a regular drill bit - I make stuff like that all the time.

As for Alan Camby - I think you've mounted the bottle jack upside down. I have seen a LOT of presses and never seen one mounted like that. Surprised it's not leaking fluid.