How do I drill holes straight across a length of pipe?

[R W]

If you want the holes to go through the pipe and be correctly aligned, it will need to be marked out accurately and drilled from both sides.

 

[mikehaugen]

Use the angle iron method to get the straight line down the length of the pipe, then mark distances from ends. Take a piece of wood or steel or whatever that is the same width as the diameter of the pipe and mark a hole on center. Clamp it in you vice and line up the mark. Clamp the vise to drill press table then remove block and insert pipe into vise. The drill bit will be centered over the pipe. Now you can rotate and slide it wherever to line up the marks.

 

[jenkinsph]

I am with BCP on this and would use angle iron and a center punch followed by a pilot bit. This will be more than adequate for a bunch of harrow spikes. Make sure the tubing or pipe you use is strong enough for the job.

 

[the old grind]

... Alignment under the drill press quill is paramount!

Yes, and the angle-iron marking jig will get you parallel alignment, but as Cal points out it's drilling the backside holes that must be controlled. Marking and drilling those separately will assure that they are parallel, more critical than how precisely they are centered on the tube. You will want to keep the drill bit repeatably on center, and that's as simple as clamping a backstop onto the DP table.

I like the full length wood v-block setup to keep the tube from rotating as it goes across the table for each hole. Rotate & re-clamp to it for the back side. If the tube/fixture is long enough, have a helper to hold the overhang (.. & don't have him/her birdwatching instead of helping to keep it level .. BTDT) Since any flats made to ease drill centering may not be consistently perpendicular to the quill a center drill or split point (preferably 'stub' length vs 'jobber' length) would make things easier.

btw: IMO, maintaining position to the hole and switching bits more back & forth per hole is worth the trouble of twisting the chuck key vs doing all holes between bit swaps and re-centering the part for each finishing pass. I'm sure your patience would be rewarded in tight planar alignment of front & back holes for the tines, esp since this is a one-off & not production wok. (.. yet? )

Be sure to add pics so we can copy your gadget after you've engineered (.. scrapped, re-done, etc) all the hard parts.

 

[kacole]

a center finder is the only way to go. they are a little high but if your gonna be drilling pipe they will make you life a lot easier and it will be right https://pipefitter.com/store/centering-head-standard.html

 

[bcp]

a center finder is the only way to go. they are a little high but if your gonna be drilling pipe they will make you life a lot easier and it will be right https://pipefitter.com/store/centering-head-standard.html

I've seen those, but don't understand them. No matter where or how I centerpunch a pipe, the mark is at the end of a radius line. Does it only work for finding top center (or other angle) on a fixed position pipe? If the pipe is loose and I want a straight row of holes, why would I want to use that instead of a straightedge, like an angle iron? Why would I use it for any number of holes if I have a centered v-block on a drill press?

Bruce

 

[kacole]

it works on all angles, if it was me i would still use the angle iron and make the strait lines then punch mark where i wanted the holes then you can set the center finder to 0 (the bubble rotates to change the angle) then rotate the pipe in the vise or whatever your using to hold while you drill till the bubble is level and that will be top dead center. If something moves on you, you can still go back to one of the punch marks and get everything back to top dead center

 

[kacole]

really easy to use

 

[chevy]

A Wooden V block has always worked for me with a drill press. Center the bit in the bottom of the V. Clamp the block to the drill press table, lay the pipe in the V & drill holes.

 

[bigdeano]

I did jobs like this lots of times when I was working as a machinist, usually in a milling machine, but a drill press works fine too. Clamp your vice on the table with the fixed jaw the proper distance in back of the spindle centerline so you're drilling through the center of the tube. Clamp a short piece of angle to one end of the tube and put a level on the angle so when you clamp the vise the top of the angle is level. Repeat for each hole. Use a good size center drill for each hole and change bits so each hole is finished size before loosening vice. Use a drill bit large enough so it doesn't wander when going thru the bottom side.We did this on 20' long shafts to line up keyways or holes thru shafts.