Introduction: A Small Low Profile Machine Vise
I knew my small old horizontal milling machine needed cutters, an arbor and arbor support, a drawbar, guards and a vise when I got it. It turned out it needed a lot more than that.
I have a nice old Wilton 3 1/2" drill press vise, it has a fast action screw and the jaws open to 3 3/4" but are 1 3/4" high so it's kind of too tall for the small stuff I usually have to mill. I tried using a cheap imported drill press vise I got from a yard sale and it was difficult to rely on for a single part and impossible for two, but its very obvious shortcomings made me read about different types of vises.
At the time I looked there seemed to be fewer affordable options. First I checked out Palmgren's low profile vises because they had been recommended for my machine, but decided a screwless vise might work alright, too, and later found some plansfor making them. Then I read about pull-type vises on Kurt's website, which work in a similar way. They were way out of my budget but they seemed like something I could make using a nice piece of left over cast iron I had scavenged for making a milling slide for my lathe.
The finished vise is a good size for holding little things - for comparison it's about the same size as the ones for a Taig, and about half the size of the smaller Kurt. I think it works really well.
Step 1: Design
The pieces I had, combined with a catalog diagram and a left-hand tap determined the basic design. If I had a taller piece of square cast iron I would have made it with slots in the sides instead of lugs, and if it was a little longer I would have put the thrust bearing under the jaw inside the vise.
The 3/8"-20 thread is fairly strong and left enough room so I could have a 1/4" hex drive on the end and use a ratchet for tightening it. The screw is centered in the base of the vise and pulls against the end with the fixed jaw, and the moving nut fits in a channel and is angled at the front where it presses against a similarly angled flat on a dowel pin. Clamping pressure draws the jaws together, and pulls the moving jaw and the nut together against the vise body.
What I found from a quick, non-exhaustive search both features seem to have been patented independently in 1951 in the United States by L. L. Walker and L. Pupura but I've seen it advertised that their combination is manufactured exclusively by Kurt.
Step 2: Parts
All the parts were scraps I had already, I don't know how much it would cost to buy them.
The base of the original is an 18mm thick and 15cm long t-shaped piece of seasoned gray cast iron. The stem of the t is 48mm wide, and the arms are 70mm across and are made into the mounting lugs. I have some 1/2" x 2" steel pieces that I thought about making a vise with slots in the sides instead of lugs but I don't know if it's a great material for it.
Both jaws are 2" wide steel bar. The fixed jaw is 1/2" thick and about 1 1/8" long, and the moving jaw is about 3/4" thick, and 1 5/8" long.
The screw is a 179mm long 1/2" drill rod with a 4mm piece of 5/8" pressed on the end. The bearing housing is a piece of 3/8" steel about 1" long and 7/8" wide, and the nut is a piece of steel 1"x1"x1".
There is a 2" 0.250" hard dowel pin, a 2" piece of 1/4" keystock, two 1" 1/4"-20 socket head cap screws, four 5/16" 8-32 pan head machine screws, one 1/2" 8-32 set screw, two 5/8" 2-56 socket head cap screws and a thin 1/4" shaft collar with 3/4" outside diameter.
The base is a piece of 1/2" steel plate I found that already had a stepped bore. It's about 5"x4". I made the clamping plate to fit from a big shaft collar. The locating plate is a piece of 1/8" tool steel from an old circular saw, maybe 1 1/2" long and a close fit to the width of the lower part of the slot in the vise body.
Step 3: Base
I made the base first. I cold chiseled and filed the shape for the lugs, and, I think, I belt sanded and filed the bottom side and then milled the top including the keyway, as well as the slot with it clamped to the table. This way I could adjust it square when I flipped it over to machine the bottom.
Step 4: Nut
I think the factory made nuts are cast, it took some more chiselling and filing to make the shape so it could extend forward of the angled face. I cut the angle with a 60° dovetail cutter. I drilled the nut with it clamped to the base after first drilling a pilot in the base so the setup was the same.
Step 5: Jaws
I milled the moving jaw with a small endmill so it took a long time but probably I could have made the small radius corners by drilling them first, or even by making it in three pieces, with a channel and two ends. The ends are radiussed at the bottom, in the front to clear the top of the nut, and in the back so if I ever radius the end of the base it will get another 15mm capacity. I ground the middle of the dowel pin, and honed it flat.
After milling the keyslot on the fixed jaw I fit the key to both parts and pressed them together, marked for the screws and drilled, counterbored and tapped for 1/4"-20 socket head cap screws.
Step 6: Screw
The clamping screw is threaded 3/8"-20 left hand. I used the tapped hole in the nut for a gauge since it's easier than measuring the pitch diameter with wires so it's probably oversize. I bored the housing but the outside is just sawed and filed to shape. The 5/8" collar on the end of the screw is press fit, and the thrust washer is also press fit into the housing, after filling it with grease. I didn't find the small shaft collar until afterwards so I had to make it shorter it to fit the screw.
Step 7: Swivel Base
I made the swivel base at the same time as the vise, and it helped mounting the vise in different places but was not very good for its stated purpose because there wasn't any register between the vise and swivel plate except the clamping screws, which aren't fitted to the lugs on the vise, and I didn't want to weaken the vise by milling a key slot in the bottom. It wasn't until last week I realized it already had a square slot in the bottom.
Step 8: Use
The vise had crude hacksaw marks and funny overhanging parts, and was a little out of square because of poor machining until last week. It wasn't as difficult to get the important surfaces square and parallel as the milling machine itself, which besides wear had been machined out of square and flat by as much as 0.5mm. Now the milling vise works better by what seems the same amount as it had worked compared with the crappy drill press vise, but the new paint is already coming off.