Saving Money in the Shop

In a recent post about Beck TD, I noted that some new equipment has arrived at the Grant St. Garage, including a large Index milling machine dating from the mid-50's. Here's another photo, just because I'm really proud of this acquisition. It's plenty big, standing 6' 8" tall - exactly a foot taller than I am. I have to use a ladder to reach the drawbar bolt on the top!

Any time you buy new gear, you quickly realize you need some supporting tools and fixtures.

Even though this milling machine has a large vise, there are times when you need to clamp the work piece directly to the table, and fortunately I already had a clamp set from my mini-mill:

The way this set works is to begin with a "T-nut" that slides into the milling table, and then use the various studs, nuts, and other fixtures to securely clamp the work. Unfortunately, the T-nuts in this set are sized for the mini-mill, and are too small to work effectively in the much larger Index table. Here's a photo of the small T-nut, with one of the studs threaded into it:

No problem, I thought - I'll just jump on eBay and find some 5/8" T-nuts for the Index table. There were plenty, and they were cheap enough, but none of them were threaded for my 3/8"-16 studs. When you scale up, everything gets bigger! No problem, I thought - I'll just buy the bigger T-nuts, cut some 1/2"-13 studs and use that. But no... a 1/2" stud won't fit through the slots in the smaller set's fixtures.

I could have bought a complete clamping set with the right T-nuts for about $75, but that seemed silly when I already have a set that would work fine. I decided to make my own T-nuts with the proper thread, and to make them to precisely fit the table I own instead of the "sloppy" generic nuts. Straightforward, if time-consuming. and after a couple of hours I had a nice set:

Notice in the one closest to you in the picture that I stopped the threads short of the bottom, so the stud can't pass through and damage the milling table. Getting the dimensions was a "measure and try" affair, but after the fact I made a nice drawing so I can duplicate them in steel later. These are aluminum, because that's what I had lying around. The fractional dimensions like "7/8" mean "something close," while the decimal dimensions are exact. 

Here's a stud threaded into the new T-nut, held in place so you can see how it fits in the table. The 0.475" dimension is so the top of the T-nut sits just below the table top.

One more photo, showing a right-angle fixture clamped to the table. In use, it would always be farther in, but this way you can see how two T-nuts in a row will securely clamp this fixture.

If I needed to put any sort of reasonable value on my time, it would have been much smarter to buy the $75 set, but since this is a hobby, I spent essentially nothing and got to play with my new machine to boot!