Intro: Handscrew Clamp
Handscrew clamps have been around forever but it's something that was missing in my workshop. High school was the last time I used one. long time ago but as I've always thought they looked cool I decided to make one.
The cool thing about this clamp is, even though it has two right hand threaded screws it still adjusts in the conventional way a bought handscrew clamp works. The hand over hand method. A normal handscrew clamp has opposing threads, one screw will be right handed and the other left handed. This allows the hand over hand method for adjustment to work. Usually a handscrew clamp with two threads the same will be such a pain to use they will be discarded, put away and never used again. It will become apparent how I achieve this later in the instructable.
I used wooden threads to make this clamp. Last year I made a screw threading box and since then I've meant to use the threads for something useful, so that's what I've done here. If you don't have a threading box you could either make one like I did or there are a few commercial versions available to purchase. I made a video on how to make your own on my YouTube channel. The diameter of the screws I made are 34mm but you could make screws of any size, the jaws would need making to an appropriate size to match. My clamp is quite large.
Another reason to make them is they look so cool, at least that's what I reckon.
Step 1: Preparing the Screws
I made the screws out of Camphor Laurel. It's a medium density hardwood that turns very cleanly on the lathe and also is ideal for cutting threads into. I roughly cut a blank down to size with the bandsaw, 52x52mm then cut it to length with the mitre saw to 320mm.
After marking the centres I mounted it on the lathe and turned the whole thing down to 50mm diameter. This will be the thickness of the handle, you could turn it down more but a thick handle makes it easy to grip and apply pressure to the clamp.
Next I used a story stick I made. This is just a stick with all the relevant markings on, so when I make any more clamps I don't need to measure everything over and over. I marked where the handle finished then turned down the rest of the screw to the required diameter, 35mm in my case.
The two screws are different, one has a notch near the handle and the other has a notch near the end. The plan I provided will show the layout better.
Using the markings again on the story stick I marked and turned the relevant notches etc, for each screw.
I put a chamfer on both ends of the handle, the notches and the end of the screw, this makes it easier to start the threading of the screw.
Step 2: Making Threads
As I said earlier I used my home made threading box but there are commercial ones available too. They are a great tool to have for making vices, clamps and even decorative nuts and bolts.
I soaked the screw blanks in linseed oil overnight. This helps stabilise the wood fibres and helps for a cleaner thread. When cutting threads there is a chance of some chipout, it won't affect the way the threads work but it can look a little unsightly. Different wood works better than others, I like to use camphor laurel as it cuts clean threads without soaking in linseed oil. The linseed oil still improves the Camphor Laurel slightly so it's still worth the extra process. If a wood turns well on the lathe or carves well then it will be suited to cutting threads.
When cutting the threads, the screw with the notch near to the handle only needs cutting up to the notch.
It won't be possible to cut the threads all the way up to the handle on the other screw as the threading box will bottom out on the shoulder of the handle. An allowance will be made for this when making the jaws.
Next we move on to the jaws.
Step 3: Making the Jaws
I used some old packing pine for the two jaws. I'm not sure where I acquired it but it was fairly substantial and as my screws are quite large, the jaws need to be in proportion. I cut them to size 45x60mm and 400mm long. Then I cleaned them up with a hand plane. It's worth getting them as square and true as possible as they will work nicer and close together better. I made them out of pine as softwood won't mark the workpiece when in use.
Next I drilled holes into the jaws to take the screws. Careful attention is required here as each hole is different. On one jaw the two holes will be threaded but one of those needs drilling slightly wider so far down. This is because the one screw we threaded didn't thread all the way to the handle. The distance between the handle and the last thread (on the screw) will be the depth you need to drill a larger recess.
On the other jaw one hole is drilled slightly larger than the outside diameter of the screw including threads. My screw is 34mm and I drilled the appropriate hole in the jaw with a 35mm forstner bit. The other hole needs to be slightly larger than the end of the other screw. This can be drilled all the way through or it could be stopped (drilled to the required depth) if you would prefer that look.
The last thing I did was to roundover the holes with a trim router using a 3mm rounder bit. This makes it neater but also reduces tearout when the threaded holes are threaded with the tap.
Step 4: Threading the Jaws
Using the tap, thread the two holes.
Both holes are in the same jaw and the reason the clamp adjusts in the normal handscrew manner. A handscrew clamp usually works by one screw going through a jaw and screwing into to the opposite jaw, then the other screw going back through that jaw and screwing back into the first jaw. For this to work with the easy hand over hand adjustment the two threads have to be opposing. You can still use two right hand threads to make a clamp this way but it will be a pain to adjust. So much so, you will probably never use it, at least in the middle of a difficult glue up.
The video may help show this better.
Step 5: Making Collars
The collars are made to fit around the notches in the screws. They don't actually have to take any strength but they do keep the clamp together. The clamp would function without them but it wouldn't be pleasant to use and the whole thing could come apart. I used Camphor Laurel again and cut two pieces the width of the jaws and 6mm thick to fit into the notches of the screws. They need to be 70mm long.
After finding the centre I drilled holes slightly larger (1mm) than the diameter of the notch in the screws.
Then I cut the two collars in half straight down the middle using the bandsaw. This could be done with a handsaw too.
Next two dado/recess needs making on the inside of the jaw that hasn't been threaded. These are to house the collars. Mark them out by using each collar and cut to the depth of the collar (6mm). I used the tablesaw making multiple passes. You could use a router or even cut by hand with a handsaw and chisel.
Next I fitted the collars to the jaw and clamped them in place. I pre-drilled and countersunk a hole in the corner of each collar.
Step 6: Making a Taper in the Jaws
I used the bandsaw to cut the end of the jaws into a taper, you could also do this with a handsaw. Then I cleaned the saw marks up with a hand plane and chamfered all the edges to make it more comfortable to handle.
Step 7: Assembly
The screw with the notch in the end is installed first. This is screwed all the way through the threaded hole nearest the end of the threaded jaw. Then the opposite jaw is taken and the end of the the screw is inserted and with four screws the collar is fitted to hold the screw in place. The other screw is pushed through the unthreaded hole from the other side of the clamp and screwed into the opposite jaw. The collar is then screwed in place and the clamp is finished and ready to use.
The only thing this clamp can't do that a normal handscrew clamp can is it won't clamp anything tapered. But that isn't something you need to do often.
And that's it, enjoy your new homemade clamp!