Round Tube Center Finder!

I sometimes have trouble aligning my drill bit with the center of a tube. Especially on larger tubes where you can miss by 1/16" and not realize it until you've already drilled the hole. Enter the Round Tube Center finder! This tool is for use on a drillpress.

Step 1: Tools and Materials

Tools

• Tape measure
• Drill and bits (I used a drill press and this tool is intended for use on a drill press)
• Hacksaw
• Files
• Tread tap (although you could just as easily use a cotter pin or rivet)

Materials

• Solid aluminum rod that will fit your drill press chuck (I used ½")
• Sheet metal (I used 3/32" sheet aluminum)
• Screw, cotter pin or rivet

Step 2: Start at the Y

While the central point of this unit is the rod that clamps into the drillpress chuck, the better place to start is with the "Y" shaped alignment device itself. Mainly because most people will make one or more attempts before getting one that is perfectly aligned.

I had a scrap of 3/32" sheet aluminum with a #6 hole in it, so that was my starting point. This project might go easier if you started with a layout and drilled the hole last.

Here's the idea. Designate a pivot point, and from that point extend two arms down at a 45° angle forming a 90° angle. Also at a 45° angle, relative to the two arms, position one arm straight up to be the indicator flag. this results in an inverted "Y" shape. The alignment arms can be any width you want, but the length from the tips to the center of the indicator flag should be the same on both sides. Drill a pivot hole such that the distance from the hole to each tip of the arms is also equal.

The indicator flag should be the same width as the rod you used. It's also a good idea to paint the indicator flag a bright color to make it easier to see. I used red.

Step 3: Make the Guide Rod

Ironically, having a center-finder would be ideal at this point.

In the end of the guide rod, drill a hole of appropriate size for your pivot screw (or cotter pin or rivet). If you are using a screw, thread the hole.

Mark a line perpendicular to the hole and cut a slot down that line. It should be wide enough and deep enough to accept the sheet metal "Y" from the previous step. A single pass from a hacksaw will not likely be wide enough. I took two passes with my bandsaw and still had to do a little sanding with the belt sander (and some filing) to make a smooth path for the Y indicator.

Step 4: Assemble the Unit and Test

Once you have the slot wide enough to accept the "Y" indicator, connect the two together.

From this point, the only thing left to do is chuck it up in the drill press and align the stock to the device. If the flag is poking out on one side or the other, the tube is not centered under the chuck. Once centered, install a drill bit and drill a hole. If the hole is through the center of the tube, you got it right!

Step 5: Watch the Video!

Comments

[Lorddrake]

i really like the concept of the off center indicator you incorporated above the pivot point.

well done!

[dougslatter]

The simple method I use is to put your Xblock into your drill vice fit the drill into the chuck and move the vice and X block under, lower the drill bit and move the Xblock so that the drill centres itself into the V of the Xblock. Raise the drill and place the pipe in position under the drill bit and drill your hole

i

[MikeD148]

my preferred method uses a 3 inch nail. Cut the head off and tighten into the drill press chuck . Use a file to sharpen the nail to a point while it is rotating.

Switch off then place the round or bar in the vice and slid it under the nail point to the approximate centre.

Place a 6 inch metal rule on top of the round object and lower the nail point onto the rule.

If the rule is sloping down to the right, move the vice and bar/tube to the right until the rule is exactly level (or vice versa if the rule is down to the left).

The nail point is now exactly over the centre of the round bar/tube. If the material is soft eg aluminium, raise the nail a little, remove the rule and lower nail and apply some pressure to mark the centre on the tube/bar.

Otherwise, carefully raise the chuck without disturbing the vice and bar or tube, fit the drill ( a small pilot drill first if a large hole is required, then follow up with the larger drill) and drill the hole.

gets you perfectly on centre every time.

[gm280]

Nice concept for sure. But the efforts to make such a tool has to be spot on as well or it will not be in true center. So if you make one, you have to pay close attention to everything for it to function correctly. You could even drill a larger hole at the top sliced area to see the red portion coming to center as well. A mark on the outside and one scribed on the red tab vertically would allow you to get it exact. But really useful project either way. Thumbs Up!