Friday, May 12, 2017

Calibrating a Drill Press

Remember that second-hand drill press I found that was made in Taiwan?  It was a little rough around the edges.  I had even checked the quill and replaced the bearings and chuck (that little South Bend chuck was worth every penny).  Well, as I've been trying to set up the tooling for building that table for my dad, I knew I needed to make sure the drill press table was level.  If it is not, you never get 90-degree holes.

In order to get it level, you have to "tram" it.  "Tram" is short for "trammel", which is a tool used to calibrate machinery.  A good trammel will give you measurements within 0.0005" - but I don't have that kind of dial indicator, nor will I unless it is a donation.  But, I needed a trammel.

I had seen a video on youtube (by Dale from Metal Tips and Tricks) on making one.  His was gorgeous, but I just needed it to work.  I ordered 1"x1" aluminum stock about 12" long, and a 1/2" chunk of drill rod, and two cheap dial indicators from Harbor Freight.  Do they have to be right on?  No, because it's a relational measurement that you are after anyway.

Once all of the parts arrived, it took me an evening of work to get the block drilled, cut, tapped, and the drill rod cut and faced, then the whole thing assembled (and to learn how to merge videos, convert them upload them and post).  Not a bad job.  Here's my new trial run at doing this - a video on youtube.

The above video was taken using a cheap Chinese "GoPro" knockoff, an SJ7000.  The camera does have its limitations (it won't do high-speed video work), but it is perfect for throwing a $40 camera into the shop and recording 1080 video (not fake 1080p resolution, the real 1920x1080x30FPS) without fear of destroying it or soaking it in cutting fluid or oil.  It's not bad, but I made the video even worse by having light behind everything - it washed it all out, but the video still came out okay (definitely not professional quality because of the way I did things).  Here's the final "product" :

With that, I threw it into the drill press and measured the table.

Forward-aft is pretty accurate (actually 0.005" off - which is phenomenal for a drill press).  Side-to-side was not so good.  It was 0.200" high on the right, and 0.200" low on the left.  That was actually amazing in itself, as all I have to do is loosen the bolt that allows it to tilt, twist the table, and re-tighten.  I'll do that on Saturday, and I should be able to drill some pretty accurate holes!

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