Kurt Vise Root Canal

A few articles ago I wrote about a pleasant machinery surprise I found. The surprise was a nice four inch Kurt vise that came with my Clausing drill press for nothing. The vise was pretty hammered when I started working on it. Originally I thought it was an offshore knockoff and even considered trading it away for something else. Lucky for me I decided to give it a bath and take a closer look.

The vise was in pretty sad shape when I started in on it. The jaw mounting surfaces were whupped from clamping parts with no jaws. The handle is lost to who knows where and the replacement is welded in place no doubt to prevent its loss. A fine patina of sulfur based cutting oil residue rounds out the gruesome picture.

The moving nut has seen the business end of too many drill bits to count. One bonus here is the table of the drill press is relatively unmolested. Probably because the vise took the bullet for the team protecting the table. Look closely at the divits on the right side of the nut. They look a little wonky to me so I started picking at them with a awl. I was able to pop out a couple of loose fillings made of epoxy.

A few minutes in the dentist chair and now we have a clearer picture of the necessary dental work. I don't understand how somebody keeps drilling in a situation like this. The one hole at the top of the image goes halfway past the vise screw. I know now why the bozons patched the holes with JB weld or bondo. They had to keep the chips out of the screw or nothing would work.

Many of the edges of the vise were chowdered up like this. A trick a dutch toolmaker showed me a million years ago is instead of filing the raised burr off is to displace the material back into position. You will need a smooth flat faced hammer. Its important that the edges between the face and the side of the hammer are rounded so you don't get a bite mark if you hit off angle.

The trick is to hammer and direct the blows so the face hits flat. If your careful and work slowly generally you can push the material back into position pretty well. If you file it off its gone forever.

A little careful tapping and the corners are mostly back where they belong. Its going to take more than a little tapping with a hammer to get this vise looking good again.

The first step in fixing the Swiss cheesed vise nut was to make a copper mandrel to fit inside the threaded hole through the center. The purpose of the mandrel is so any weld metal doesn't get into the threads. The nut would be difficult to re-thread in the lathe because of its awkward shape and odd size and left hand to boot.

The copper mandrel fits in the threaded bore with a easy slip fit. I expect this to get a little stuck after the welding.

A short preheat and it will be ready for welding. Looking for something like three or four hundred degrees F or so. Hot enough to smoke the old cutting oil.

I'm TIG welding the holes with 1/8 diameter Ni-99 rod. Tungsten is 3/32 diameter Lanthanated DC straight polarity. A reader has been asking me what kind of current I'm running on some of these jobs so I set the camera up and took a picture.

I did it twice and the current was the same at 100 amps. The machine was set in the high range which is the upper scale on the right hand meter.

It took two filler rods to fill the cavities up to this point. If I was really a dentist this would be called a trans-cavity bridge filling.

While it was still hot It got wrapped in a fiberglass blanket and allowed to cool overnight. Next up will be the mandrel removal.

The next day I went to work on removing the copper mandrel. Driving into work I thought of a good way to drive it out by just inserting the lead screw and pushing it out. I was so happy I thought of an easy way to push it out I was thinking about it during the day.

It was a great idea for about half way. The mandrel stopped moving so I had go to plan B and get medieval on it. I ended up cutting if off short and drilling as big a hole as I dared in the now dead soft copper. If you haven't experienced dead soft copper and drill bits consider yourself warned. After drilling a pretty good sized hole through it still wouldn't come out so I used a jab hacksaw to split the copper tube that was left of the mandrel and collapse it into the hole. I didn't take any pictures of this process as I was annoyed and just wanted to get it done.

I did some sanding on the weld buildup to make it look more presentable. It least the holes are patched and no chips will get down into the screw and nut assembly.

The finished product. Not factory new but definitely better than usable. I made a set of steel jaws with a built it parallel step and vertical vee groove. Not a bad ending for a vise that was close to its expiration date. I called Kurt to ask if they had parts for this vise. I was told this vise is a very early model. The clues were the five inch width and the lack of a needle thrust bearing in the screw. This dates it to the dawn of Kurt history. A real relic.

Thanks for looking.

Tom Lipton