Aligning Misaligned Holes

Despite your best efforts, sometimes the holes you drill for a project will not quite align with those in the mating parts.  It is maddening, and often you feel dumb because it is messed up, but there are ways to fix misaligned holes.  Here are a few.

This story and these images are illustrations of my own little mess.  Yeah, it is a little embarrassing, but fiddly mistakes happen.  Such is life in the shop, and so goes some DIY projects.  But, enough lamenting.  The fix is actually pretty easy.

The Silly Misaligned Holes

This project is a custom carrier for my truck using a standard 2″ drawbar and receiver.  With the parts fabricated, and the hole drilled for the pin (in the drawbar), it was just a matter of hooking it up.  But, the pin for the drawbar would not go in the hole.  Almost.  It went in one side, but not all the way through as in the photo.  Twisting the pin and the fixture still did not make it to fit.  And, you can see in the photo, the misaligned holes are are just slightly off.  Bummer.

Well, somehow I always feel a little stupid when something does not fit.  I thought I measured carefully, and I thought it would go right together.  Yet, I do like a close fit, so even a little off and . . . well, you can see, they do not quite align.

We can have another discussion sometime about tolerance with less than super accurate machinery.  However, that is not the point here.  In the meantime, we can fix these misaligned holes.

Possible Solutions

So, here are three ways to solve the problem.  And, a bonus 4th way for a super quick fix.

1. Re-Drill the new hole slightly oversize with a larger drill bit.  That is pretty easy, and it is clean and professional.  Yet, it makes for a looser-ish fit.
2. Use a rat-tail file or a rotary file, or a grinding tool to enlarge the hole only in the area needed.  I could just mark the area with a Sharpie while it is in the receiver, then pull it out and file some on that side.  This method is also a great solution is pretty easy and straightforward.
3. Then there is the fun one . . . Run the same drill bit through the assembly.  That will assure the pin fits by forcing alignment of the misaligned holes.  This method is a little dangerous because it will cut portions of both parts (not just the new part with the new hole).  However, if the new material is reasonably thin, it will cut more from the thinner piece.  Also, please note that this does not work well for thick parts.
4. If you are really in a hurry, just use a smaller pin or a bolt with a little smaller diameter.  This is a 5/8″ pin, and the loads are pretty light, so why not just toss in a 1/2″ pin?  Or use a 9/16″ bolt?  Both of these will work.  Just make sure you choose an appropriately strong bolt or pin.

Solving the Misaligned Holes

It would be great to just use the simple techniques for matching bolt holes in the first place.  But, the hitch is on the vehicle already, so that is out of the question.  In this case, since there is only a small misalignment, and the new material is thin compared to the receiver.  (That means the drill will cut much more from the thin material than from the thick, so it will not bugger up the receiver.)

I choose option 3 – run a chase drill through.  OK, I will admit it . . . I like using power tools, so just blasting through it is also some of the motivation.

Method 3 works pretty fast, usually.  However, the drill needs to be sharp, and the drill motor (for a hole this large) must be quite strong because the drill bit will catch the one edge then suddenly yank to stop the drill.  Just be aware that this technique with a drill bit is a hack job, not precision work.  And, there is a risk of buggering up a drill bit – not to mention bloody knuckles – so control the process.

For this job, I chose a stout pneumatic drill with a relatively slow spindle speed and tons of torque.  Just gotta be careful with fingers, because if the drill bit jams, it will twist violently and potentially smash fingers.  Remember, this method is fast and straightforward, but it is still a hack.

Right Tool For The Job?

Method 3 with a drill is technically not the “Right” way to do this job.  Yes, they do make tools for this exact situation.  They call them “Bridge Reamers” which are also sometimes called “Construction Reamers”.

Bridge Reamers are used to align existing holes prior to installing a bolt or rivet – or in our case – to install a pin.  The point of the reamer is smaller so it fits in the space of the misaligned holes, then the tool tapers out to the size needed for the fastener.  Of course, they come long and short for access in various areas.

With the right tool for the job, aligning misaligned holes is easier and faster.  Also, the risk of jamming the drill and smashing fingers is greatly reduced.  A big plus!  And, you have a lot more control by how fast you insert the tool into the hole.

I do like this method, and would do it, but don’t have this tool in the right size.  That is the way it goes, often, in the shop.  We need something done, and we don’t want to wait to get the right tool.

Well, if you need a bridge reamer, you can find a selection at Drills & Cutters.  (No association, just a place I’ve purchased stuff before.  I’m giving the link because this image came from their website, and I like to acknowledge sources.)

Job Done.

In the end, it worked out well for this quick project.  With the holes aligned, the pin goes right in and there is not much play in the attachment.  Nice.  Maybe next time I can do a better job marking and drilling to avoid the misaligned holes.  After all, that is the best solution.  “Quality is Free if you do it right the first time.”

For the record, even though it is a hack, we think it is a good one.  At least for the right situation.  We recommend this technique for aligning holes in parts such as the telescoping legs of our Gantry Crane, because proper fitting pins are important for Safety.  If the holes are not perfect, sometimes the misaligned holes need just a little help getting there.  Method 3, as in these photos, is pretty easy and it does the job.  Of course, it is even better if you have a bridge reamer.

Good luck in all your DIY Project Drilling !!