Need Steel Drilling Help

[All]

I cannot imagine a more cumbersome arrangement than an X-Y table, permanently attached to the drill press table, when trying to align the bit to a center-punched hole.

Are there any other problems that you have experienced using an X-Y table besides aligning the bit to a center punched hole?

It could be that I'm doing things all wrong, and this discussion is a good way to discover what the best practices are in using a drill press to drill through metal.

I have found that the X-Y table is actually helpful, rather than a hinderance, to aligning the chucked drill bit in the quill to center punched holes in the material to be drilled. Perhaps one of the most critical aspects of assistance is that the X-Y table enables the work piece to be moved AFTER it has already been clamped and secured.

Sometimes, the act of clamping a work piece may also shift the work piece, as clamping it, with either a vise or with vise grips, removes the air slack between material and jaw.

Whether it is an air gap, or a film of viscous cutting fluid/oil, or a rogue chip that got trapped between the material and the vise jaws, there can sometimes be a shift between where the part was positioned and held by hand, versus where the part ends up once held by a tightened down vise.

An X-Y table is useful for correcting any inadvertent shifts, WITHOUT having to loosen the grip of the vise in order to make the correction.

I would change careers rather than have to deal with such nonsense.

Does your current career involve lots of drilling with drill presses?

Your trio of drill presses with tool boxes is neat. My drill press looks similar to the one you have on the right.

Very curious to know who you learned this technique from. Surely not from a professional.

I have no idea who designed the X-Y table, but whoever designed it made it self-evident as to how to use it.. hence no one taught me. No one had to. I simply turn the dials to make the table move where I want it to go.

It takes only a split second to line it up when you can freely slide the workpiece around.

The work piece can still slide freely, by hand, on the X-Y table, prior to it being clamped.

In the present and specific case of drilling a series of eight (8) 1/2" holes through the longitudinal centerline of a 3/8" thick flat bar of steel that is only 1-1/2" wide, which is a fairly narrow width within which the 1/2" holes must more or less be centered so as to leave an equidistant margin on either side of the drilled holes across the narrow flat... an X-Y table is helpful by allowing the part to slide laterally along it's length (30"), while not traveling forward or backwards at all.

My flat bars are already drilled and done, but my questions regarding ideal pilot drill diameter remain.

I found that 1/4" was a bit too fat for an initial pilot. I don't remember the angle of the drill bit tip, but I can see where that angle would make a difference in how the bit nests into the center punch mark.

I ended up going the other direction, making the initial pilot with a 3/16 diameter bit... the smallest diameter I had with a triangular cut shank to better nest within a 3 jaw drill chuck without spinning or slipping.

I followed the 3/16" up with a 1/4" pilot, still stopping short of punching all the way through, in order to create the bowl in the hole to conserve cutting fluid.

I then jumped to the final diameter. While I said 1/2" diameter in my description of the project, the actual diameter I drilled was 33/64" , to allow wiggle room for the 1/2" bolts when aligning these bars through multiple parts simultaneously when installed.

Future corrections I could make, as instructed by GJ'er responses since I resurrected this thread:

1. I should purchase a centering drill

2 I should purchase a Starrett Automatic Center Punch, since the half dozen automatic centering punches that I already have don't work consistently enough to bother using.

 

[MushCreek]

I have a full range of these, from tiny, easy-to-break ones up to a 5/8" body diameter. The idea is that they are short and rigid, so they don't skate around on the surface of the steel. You don't need a big starting divot; the size of the web of the big drill is sufficient.

 

[whateg01]

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My flat bars are already drilled and done, but my questions regarding ideal pilot drill diameter remain.

I found that 1/4" was a bit too fat for an initial pilot. I don't remember the angle of the drill bit tip, but I can see where that angle would make a difference in how the bit nests into the center punch mark.

A split point drill will drill easier than a chisel tip. With a drill press, though, even a well sharpened 1/4" drill should cut easily enough to not need a pilot.

As far as the ideal size, the width of the web of the bigger drill is a good guide. This leaves most of the big drill cutting, reducing chatter which is what destroys cutting edges on drills.

 

[ez-duzit]

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In the example you show, the X-Y table is a hinderance and is entirely unnecessary, as you only need to open the vise in order to reposition the workpiece for the next hole.

I have been a professional boat builder for nearly 50 years, and use my drill presses virtually daily. My recommendation is to unburden yourself from this tedious reliance upon such contrivances which only cost you time, and vastly limit the usefulness of such an important machine.

 

[MushCreek]

For a bunch of evenly spaced holes, a dedicated fixture is the way to go. Drill the first hole, advance to the next position, where you put a pin into the fixture to set the spacing. Then you just keep repeating that operation. Many years ago I worked at Kenyon Marine, and we drilled miles of track that way.

 

[tarbellb]

For this exact type of operation I would be using fence not a xy table

Set the fence at exactly centerline then move piece along fence hitting your marks


And yes! buy a decent auto punch and a couple of enter drill bits

 

[All]

Once the X axis was set, it wasn't moved, and the back jaw of the block vise on top of the XY table became the "fence" so to speak.

With front jaw of vise loosened, the piece was moved along the "fence" of the back jaw freely by hand.

The XY table is NOT used to move the work from hole to hole, in case there is any misunderstanding.

The holes were 2-1/2" on center, within groupings, but there were multiple groupings on the same bar, and the cadence of the groupings did not match the cadence of the individual holes within each grouping, as the holes were positioned to match existing structures that the bar would be bolted to.

And each bar was different from each other, as far as relative position of groupings. The bars were made to match the idiosyncratic installation of an existing structure built by another party.

Therefore, a single jig, or a single stop, could not be used to drill all holes, as the groupings were out of cadence with each other.

The X axis (front to back) of the XY table stayed put, once set to the longitudinal center of the flat bar.

The Y axis (side to side) of the XY table was only moved minutely, as in micrometers, in order to make up for any inaccuracies from hand positioning and vise jaw tightening.

With the drill motor off, the quill was lowered to feel how the bit engaged with the ***** mark of the center punch. The piece was adjusted infinitesimally left to right as needed... by hand before tightening the vice, and by the Y axis after tightening the vise, if there was any change imposed by tightening the vise. There was no cranking the XY table from hole to hole.

If there was any question about alignment, the spindle was rotated 90 degrees to orient the two flutes of the drill bit perpendicularly to how alignment was checked the moment before.

If there was really a question, since the work was recessed into the vise jaws that were broad enough to prevent rotation of the work, the drill motor could be turned on and the quill lowered to just graze the work piece, without pressure or penetration. The grazing would leave a circular witness mark as to where the pilot hole would end up.

If the vise jaws were slightly loosened, the grazing (of a small diameter pilot bit) could self seat the piece that was recessed within the vise jaws to prevent rotation of the work itself. Such grazing is with no pressure applied.

A caveat to all of this is alignment of drill press head to drill press table, especially with a tubular column, gear track, and crank handle typical of a floor standing drill press.

When cranking the table up and down, it tends to wig wag with each crank of the handle, and of course the table has to be loosened in order to move it.

The loss of head to table alignment is why I prefer not to adjust the table up and down if it can at all be helped, because I don't want to have to realign the drill head to the table to 90 degrees again.

 

[All]

I have the MSC Direct webpage open to Center Drills and Countersink Sets.

Looking for recommendations.

I don't always drill holes with a drill press. More often than not, I use a hand held drill.

All 90 holes drilled in the two tubes shown below (from the single 6"x6"x1/4"x36" tube that I asked GJ about cutting in half about a month or so ago) were drilled with a hand held battery powered drill on a piece of cardboard on the ground, and the holes on one side of the tube had to match corresponding holes on the opposite side of the tube, as 10" long bolts passed through the opposing facets of the tube.

Obviously, I couldn't drill straight through one side of the tube into another, due to the 6" diameter of the tube, so I have become more conscious of the need for precise centering of holes, and since I have neither the space nor the funds for a milling machine, I should at least invest in a set of quality centering bits.

If there is any difference in types of centering bits that work better with a 1/2" chuck on a hand held drill motor, as opposed to a 5/8" chuck on a drill press, I'd be interested in learning about the different characteristics of center drill designs optimized for these two different drilling applications as well.

 

[ez-duzit]

Center drills are designed to be used in a lathe to produce turning centers. Ideally one would use a spotting drill, first, in the centerpunch divot, followed by the final drill size, which could be preceded by a small pilot hole.