alex71
Well-known member
A couple of weeks ago I finally found a mag drill. I've been looking for one forever, and I had a job in mind for it....
I have a 3x6 foot ground cast iron surface plate that I've been using for a workbench/welding table for a while. Its a nice heavy chunk of metal, and has a lip for clamping stuff to, but I've found myself wanting to clamp stuff to the middle of the table many times. If the table was steel, I'd just tack the work to it and be done with it, but being that its cast iron, that wouldn't work. I needed to drill and tap some holes so I could use the clamping kit from the mill on the table.
I laid out a grid of 72 holes (minus a couple in the corner where the vise is mounted) on 6 inch centers. 12 on the six-foot side, and 6 on the 3 foot side. Drilled, tapped, and inserted 1/2-13 helicoils. The hardest part of the job, by far was laying out the grid. I wanted it as accurate as I could reasonably make it, and it wasn't easy to do. The actual drilling and tapping wasn't difficult. Time-consuming, tedious repetitive, but not difficult.
Click for hi-res image.
Layout out the grid. Tools used: Combo square, machinist's square, 6-inch scale, number 2, sharpener, center punch and hammer.
Repeat the following steps, 72 times:
Line up the drill:
Drill:
Tap (using the mag drill, which is a hell of a lot easier than doing it by hand)
I deburred all the holes with a 90 degree countersink in a hand drill after drilling/tapping. (not shown)
Insert helicoils (this is what's left from a bag of 100)
Here is what I wound up with:
And after a bit of cleanup, and a couple of coats of wax... I'm happy with the results.
I have a 3x6 foot ground cast iron surface plate that I've been using for a workbench/welding table for a while. Its a nice heavy chunk of metal, and has a lip for clamping stuff to, but I've found myself wanting to clamp stuff to the middle of the table many times. If the table was steel, I'd just tack the work to it and be done with it, but being that its cast iron, that wouldn't work. I needed to drill and tap some holes so I could use the clamping kit from the mill on the table.
I laid out a grid of 72 holes (minus a couple in the corner where the vise is mounted) on 6 inch centers. 12 on the six-foot side, and 6 on the 3 foot side. Drilled, tapped, and inserted 1/2-13 helicoils. The hardest part of the job, by far was laying out the grid. I wanted it as accurate as I could reasonably make it, and it wasn't easy to do. The actual drilling and tapping wasn't difficult. Time-consuming, tedious repetitive, but not difficult.
Click for hi-res image.
Layout out the grid. Tools used: Combo square, machinist's square, 6-inch scale, number 2, sharpener, center punch and hammer.
Repeat the following steps, 72 times:
Line up the drill:
Drill:
Tap (using the mag drill, which is a hell of a lot easier than doing it by hand)
I deburred all the holes with a 90 degree countersink in a hand drill after drilling/tapping. (not shown)
Insert helicoils (this is what's left from a bag of 100)
Here is what I wound up with:
And after a bit of cleanup, and a couple of coats of wax... I'm happy with the results.
Last edited:
You only get huge pictures if you click.