View Full Version : screw slotting and other ideas for a cross slide milling table

12-16-2004, 10:21 PM
I have only a lathe and I want to make a bunch of 1/4 set screws so I thought about using a table on my cross slide with with a slitting saw held on a mandrel between centers (dremel cutting them is OUT...) . I want to screw the threaded pieces into the table and slit all of them (maybe as many as 20) in one shot but how would you hold or tighten them down? I have a block of aluminum about 1" thick and was going to use this with drilled and tapped holes, all in nice rows to put the threaded parts into. I have a disturbing number of bolts from years of scavaging so I thought I would cut the heads off and use them. Also, I don't anticipate having a mill in the 10 year forcast so does anyone know of an easy way to use packing or some other machination, in a vice that I can attach to said crosslide for raising and lowering stock, kind of like in a horizontal mill only without the ability to raise the table? I appreciate any ideas or input. Scott.

12-17-2004, 10:42 AM
Ewe, if there's anything I hate, it's straight slot screw heads :D

But what you could do to hold them is make a split fixture block. A simple way to do this is to get an extra deep nut (a coupling nut) and saw it down one side with a hand hacksaw. You can then collapse the nut in a vise type fixture and grip your blanks without marring the threads.

Or, you could get fancy, and make a fixture to do the same thing, starting with two pieces of stock, shimmed a few thousandths apart. Drill and tap holes right on the edge, forming half holes in each side of the block. Remove the shim, and then install your blanks in the fixture and reclamp.

BTW, PM me if you are in need of a cross slide vise for this project.

12-18-2004, 10:23 PM
Huflundung, I will have to think about how to apply this to slitting several screws at one time. At first I thought about just running several bolts into threaded holes in the crosslide block I am making and tightening them down then cutting the heads off relying on torque to hold them. This seems dangerous if they were to work loose when the saw was on them. I will keep that vise in mind. Scott.

12-18-2004, 11:32 PM
Scott I have to ask :) why the slotted set screw?, you can get socket set screws for probably no more then $6-$8 dollars a hundred.

12-19-2004, 12:33 PM
Here's another plan which may work more securely for multiple screw holding: my previous plan had a fixture that was split parallel to the screw axis. You are right, this may or may not hold all the screws tightly, and likely is not reliable.

Instead, this time, make a fixture consisting again of a sandwich of two plates stacked on above the other. Drill and tap holes for your screws through both plates (Note, the plates must be clean and tight together, and threads tapped with them tight together!). Now, at a few other places on your plates, drill and tap holes through only one of the plates. Use these holes to install "push" setscrews. After you have screwed the blanks through the two plates, then, push the plates apart with the "pusher setscrews". Hopefully this would create enough bind effect to hold the screws for slotting.

Another option is to use a single plate with tapped threads, and use a jam nut on the opposite side to hold the screw while it is slotted.

A collet fixture would also serve for doing singles. There is not a lot of torque reaction put on the screw when being slotted across the center.

12-20-2004, 09:32 AM
All this for slotted set screws - phew - .
When I need something slotted for a screwdriver I usually hold in in vise-grips and push it into my bandsaw.
All the fixturing advice above is perfect. The only other I can think of is to drill your (tapped) holes through in your aluminum plate,. make sure it has full support underneath and drop spacers into the holes to tighten your threaded blanks against.
I would imagine your slitting saw (for a screwdriver) will be narrow and will generate very little cutting pressure if operated correctly.