Introduction: How to Make Handscrew Clamps
I've always liked these handscrew clamps and own a pair but sometimes they are too big and a bit cumbersome. So I decided to make a smaller pair for smaller clamping jobs. Mainly I want to use these for work holding or for holding small diameter dowels when cutting them on the bandsaw.
3/4 inch Square Hardwood
1/4 inch Brass rod
3/8 inch Brass Tube
3/8 inch Mild Steel Rod
1/4 - 20 Right Hand Tap and Die
1/4 - 20 Left Hand Tap and Die
Hacksaw or Portable Bandsaw for cutting metal
Various Grit Sand Paper
25/64 inch Drill Bit
5/16 inch Drill Bit
3/8 inch Drill Bit
Brass Wire Brush
Danish Tung Oil
I first prepped the wood, in this case its some 3/4 inch Walnut stock that I used. I ran the pieces through my table saw to make sure they were 3/4 inch square then I marked and cut some 4" pieces. I used my belt sander to sand all four sides and make sure they were parallel to one another.
I have to be honest here before making these I had no real idea of how these worked so I sort of had to figure it out as I went along. They are fairly simple but I had never really put much thought in to the mechanism of their operation.
I bought some barrel nuts aka cross dowel nuts that I used to mock up their location on the wood blanks. When I found what looked about right I marked the wood for drilling. Their location isn't really crucial as long as you stay above the half way mark of the length of the wood and space them evenly. Also make sure the holes are drilled in the same location on both pieces of wood. The barrel nuts were 25/64 inch in diameter so I drilled those four holes first. Initially I thought I would be using four purchased barrel nuts for each clamp, later I realized I had to make my own for one side.
After making the holes for the barrel nuts I next transferred the lines to the adjacent side of the wood in order to drill the holes for the screw portion. I used a 5/16 inch drill bit for these holes. You can see in the last pic the eight holes drilled in each piece. You will also notice that the 5/16 inch holes are elongated this is to allow for some play side to side where the threaded rods come through. To elongate the holes I just twisted the wood blank up and down while drilling. This could also be done with a router but I chose to use the side of the drill bit.
I cut a 12 inch brass rod in to two equal sections using my portable bandsaw table.
A little bit of a disclaimer I am skipping my mistakes and getting to what I eventually figured out after some trial and error and a little research. I wasted about 2 feet of brass rod in my experimentation, I really should have just done the research before my first attempt and saved some time and material.
The first picture shows you a threaded brass rod and a brass rod with some markings. In order to get these clamps to work the screw portion has to have two different thread types, one half has a right hand thread, your traditional thread righty tighty lefty loosey, and the other half has a left hand thread. The rod with the markings shows an exaggerated view of what the threading on the rod actually looks like. This threading is necessary if you want the clamps to work like the traditional ones where you can hold the handles and spin them like a bicycle crank. In order to accomplish this you need two thread cutting dies a Right Hand thread cutting die and a Left Hand cutting die. You will also need a Left Hand tap as well because a left hand threaded screw will not screw in to a right hand threaded nut.
I used my bench vise to hold the thread dies. I made sure to round off the ends of the brass rods so they would find the die center more easily. Next I chucked the brass rods in my hand drill and ran them through the right hand thread cutting die but only to the half way point of the brass rod. Then I removed the brass rod from the drill flipped it over end over end and chucked it back up in my hand drill and ran the brass rod through the left hand thread cutting die up to the half way point. I left a tiny section of brass rod right in the middle that was left untouched by either die. Ideally this should be your center point this will be important later.
If your hand drill damages the threads you can just re-align the threads with the correct die by hand. To do this I screw two barrel nuts on the undamaged end and tighten them against one another and then run them through the correct die by hand.
Now that I have left hand threaded rods I needed left hand threaded barrel nuts which are not readily available so I made my own. I had a piece of scrap 3/8 inch steel rod that I could use for the nuts. I marked the approximate length and then used my file to make a flat spot on the top. Next I used my center punch to make a mark on my flat spot. I used a drill press and drill vice fitted with a #7 drill bit, from my tapping kit, to make the hole for the 1/4-20 left hand thread tap in the 3/8 inch rod.
Next I secured the 3/8 rod in my bench vice and attached my left hand threaded tap to the tap handle and began to cut the threads. I used some oil to lubricate the tap while I tapped the hole. It is important to go slow when cutting threads you don't want to break the tap so ideally you twist a little in one direction then twist back the tap to clear the metal cuttings and then twist the tap again to cut the threads little by little until there is no resistance when twisting the tap. Once I finished cutting the tap I used my portable band saw stand to cut off the barrel nut I just made. I repeated the process several times to make all my left hand threaded barrel nuts.
The first pic shows the barrel nuts I made on the top row and the bottom row are the barrel nuts I purchased. I wanted all the metal pieces to be brass or have a brass look. There is a fairly simple way to apply a brass finish to steel with a blow torch and a brass wire brush called "brassing".
First I used acetone to clean them all up and remove any oily residue. I dried them off and then I screwed all the left hand threaded barrel nuts on to one of the spare brass rods and heated them up with a blow torch. As the metal heats up I brush it with the wire brush. The heat of the metal will melt the brass from the brush and deposit it on the steel as a sort of brass plating. You just have to get the metal hot enough for the transfer to occur. Its a little bit of trial and error but you know when you get the metal hot enough because it starts to turn brass colored.
I repeated this process for the right hand threaded barrel nuts, it didn't work quite as well but it was good enough.
I needed to make handles for the clamps so I used some more of the 3/4 inch walnut which I cut in to 2-1/2 inch long pieces. Using a 1/4 inch drill bit I drilled a 1 inch deep hole in the center of each piece so I could mount it in my lathe.
I used my pen mandrel and a live tail stock on my lathe to hold the handle blank in place, I added some blue tape around the mandrel to get a nice tight fit on the blank. I first cut the shoulder for the ferrule making sure to regularly check the diameter with some calipers. Once the shoulder for the ferrule was cut I then shaped the rest of the handle. I didn't go for anything too complicated just a nice simple shape.
For the actual ferrule I cut a few pieces off of a 3/8" brass tube. I cut the brass tubing a little long and then sanded off any excess so that it would sit flush with the handle.
Time for assembly, the right side or the piece of wood on the right has the barrel nuts that are right hand threaded. The piece of wood on the left has the left hand threaded barrel nuts I made. Next I inserted the threaded rods and only just threaded them in to right side. The key here is to make sure that the space from the wood to the center of the rod is the same on both sides. This is important because as you twist the clamp closed if the center mark is not in the center then one side will hit the center mark first and get stuck due to the lack of threads. Ideally you could compensate for this by making one side slightly longer to give more room for error when you assemble the pieces. I figured that out after the fact.
I decided I wanted the clamp to spread about 1-1/4" inch wide. So I opened the clamps to that width and prepared for gluing the handles on.
I did a quick mock up to check my handle placement. I then mixed up some 5 minute epoxy and glued the handles in place. Make sure to leave some room between the handle and the clamp jaw so you don't glue the handle to the jaw. When the epoxy dried I fully extended the handles and cut off the excess threaded rod on my portable band saw table.
In order to give the clamp it classic look I trimmed off the corners of the jaws, then hand sanded the clamp using 220 grit sand paper. I mostly just knocked off the edges and corners. Then I added 3 coats of Danish Tung oil.
I'm super happy with how these turned out, and I know they will get a ton of use in my shop. It was also very satisfying making my own barrel nuts. Its always a good feeling when you can make most of the parts for a build by hand. I hope you all find this helpful and maybe it will inspire you to make your own.
Second Prize in the
Build a Tool Contest