Two drilling questions

I too have a bunch of cheapies. I think we have replaced bearings in all of them. And, the bearings don't always fit into a good bore and the shafts aren't great fits either. I won't buy them anymore, there are too many used good ones out there.

You might have better luck with single flute step-drill bits in sheet metal. They are less likely to make oblong holes in thin stock.

for sheet metal use a unibit, they will cut a round hole.

above is just one size, they make 2 or three others.

Thank You, Randy

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So find some _decent_ drill presses, and expect to pay at least 10x for one instead of 4x -- but expect to never mess with it again.

Alternately, as 'Buerste' suggests, get an older good drill press, rebuild it, and use it forever.

Getting a cheap Chinese tool is kind of like getting a comprehensively clapped-out tool -- you can't rebuild it, because every part is just _wrong_; by the time you got all the problems fixed you'd have a scratch- built tool with the original power cord.

I have one with a bad (intermitttent) power cord.

Have you tried the "bullet-point" drills? These were made for thin stock, I have a set I use for just that. B&D I think is the one that owns the trademark but there are other makers. If you haven't seen them, they're like a two-step step drill, the small nib acts like a spotter. No wandering. I've used them on 4140 thinwall tube, worked fine. If you need accuracy, go with bushings and a drill jig. Heinrich makes a number of different ones for drilling on the centerlines of round stock, for a price. Strictly production-level stuff. MSC has them.

Stan

Solid carbide drills are great for drilling hard to drill materials.

Just yesterday I used one to drill a bearing ball made from bearing ball steel. Even with the carbide drill, it generated a tremendous amount of heat. I drilled it with a 3/16" carbide drill, and then enlarged the hole with a 3/8" carbide endmill. This is a stupid thing to put a ball at the end of a formerly ugly key for a Jacobs 18N chuck.

In any case, aluminum is not a hard to drill material, but I think that what your application lacks is tool rigidity. Assuming that your drill spindle has no runout, I would try very short drill bits that do not flex much when coming out of the drilled hole. McMaster has plenty of those.

Use of carbide drills in cheap drill presses is questionable, as they do not like to flex much and can be broken by excessive runout or just flexing of the drill press. If I were you, I would try short drill bits first.

i

For small diameter holes I like brad point bits for aluminum or soft copper. For larger holes the uni-bit works well.

You might also get good results drilling close to size with a center drill and then finish with an end mill.

You can also try punching the hole. the technique I would try would depend on how many holes I needed, and how accurate I needed to be.

As to your inquiry about spade bits I find these to be virtually useless.

There's an old boy on ebay that has a lot of drill bits--he calls them "Piloted" they have an undersized 3/8 to 1/2 start which gives you your

3 lobed hole in thin metal, but then the remainder is full size and seems to ream the hole true round.

I'm in the market for a good used drill press. Do you have any suggestions as to brand/type? Smaller is ok, low speed (as for a hole saw) would be a plus. Everything I've seen is an East Asian import except for one vintage Delta with a bent spindle.

bob prohaska

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I have a hobby of buying stuff in liquidations. Here are some observations.

We are in the middle of a once in a generation destruction of American metalworking industry. This may not necessarily be a negative for the country, as the old technology would possibly make way for new technology, but this old technology is valuable to hobbyists because we can actually comprehend it.

So, where to look for those drill presses?

The answer is, at liquidation auctions.

Two weeks ago I bought an old 1/2 HP Craftsman bench drill press for $15, for example. It worked great. It is nothing like what you can buy at Sears today. It weighed at least 120 lbs.

check out also

(the motor here may be somewhat underpowered)

i

Where do you live? Ive got several Deltas, Rockwells and whatnot.

Gunner, California

Whenever a Liberal utters the term "Common Sense approach"....grab your wallet, your ass, and your guns because the sombitch is about to do something damned nasty to all three of them.

Watch on Craigslist and look in the local shopper newspaper. I'm partial to Rockwell, old Delta Milwaukee and Walker Turner drill presses. All three companies became related due to buyouts. I prefer step pulley models due to simplicity and I'm told that there was a period of time in the (I think) 1970s-1980s where Rockwell variable speed machines were not well made. If you're in central PA, I"m going to sell my bench model Walker Turner which I replaced recently with a

20" floor model Rockwell.

RWL

Thanks for all the suggestions. Getting better presses is ideal, but that's going to take some time and I'm just looking for a easier option for now. The right bits work fine. I was using bits I found with an almost neutral rake and that solved the problem. But I can't find those or anything like them anymore, nor can I find anybody that is capable of sharpening some like them in this ever de-evolutionized world where nobody knows how to do anything anymore... So I'm still looking. I tried the Unabit and they do work well, but sorry... I should have mentioned this is mainly for doing two sides at a time through tube. So every extra step greatly lengthens the amount of work. Ideally I would love to find letter sizes, which would eliminate one more step. I'm mainly doing about 1/8 or #27 to about F or G. The biggest is maybe 21/64, but for some reason those don't seem to have a problem. mainly around the 1/4 size do. Somebody said I should try the straight flute or the one I originally showed, because they have a low rake. But I've tried so many, I just wanted to see what people thought before I spent more money. Some day I want to do this with CNC, but that's a ways off.

On the subject of the evaporating American heavy industry... It's a sad thing, but as mentioned, there can be an up side. There's some surplus stores out there that are awesome. Stainless fasteners dirt cheap... all kinds of stuff. There's a place in CA that got a lot of it's stuff from Lockheed Burbank when it closed... They've even got some of the old metal placards and stuff.

Update... I've found that the DeWalt "Pilot Point" bits seem to work fairly well in thin stock. They still need a smaller pilot hole to work perfectly on larger sizes, but they do work. So that at least helps until I work out the real issues, which is probably just drill machine quality. But the next step is to find pilot point style bits in letter sizes. DeWalt apparently doesn't have them. I've seen other brands in the same style, but no letter sizes yet.