I've recently had a few issues with hose clamps not pulling tight enough or breaking, probably because I bought cheap ones. I ended up just twisting some wire around the hose which worked great, except for sometimes I broke the wire and other times I'd scratch my hands on the sharp end. I've seen a few different variants of these wire clamping tools floating around and they either cost a lot to get shipped to my country or require welding or access to metal lathes and milling machines to make.

I worked on a couple of different designs that would make use of the materials I had on hand and basic power tools such as a grinder and drill.

Mr Clampy Instructions.pdf
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Supplies

Steel Pipe (12mm outside, 9.5mm inside)
Steel Bar (10mm)
Steel Bar (13mm)
M8 Coach bolt
Washer
Small rods or Allen wrench

Bench Grinder
Drill
M8 Tap
Hammer
Centre Punch
Flat File
Small round file
Dremel
Buffer

Mr Clampy.pdf
Download

Step 1: Make the Body

You'll notice that the length of the parts gets smaller later in the instructions, that's because I changed my mind and cut the parts down later on. The plans have been updated to reflect the final measurements.

Cut the length of the pipe and a piece of the smaller bar and then measure off about 20mm that will be inserted into the pipe. Lock the bar into a drill and while it's spinning run a file or sandpaper over it until it can be fit tightly into the pipe. This needs to be a tight fit, once you are confident it will fit you can hammer it into place. Be careful not to bend the bar or pipe.

Step 2: Taper the Body

Now using a grinder make a taper on the bar, to do this you need to keep turning the piece while it's on the grinder. You can even place the piece in a hand drill if you want to speed this up, but I did this freehand.

The metal will get hot from grinding so either keep dipping it in water or use a piece of wood to hold it in place. The small end should be about 5mm in diameter.

Step 3: Cut the Slot

Now mark out where you need to cut the slot, drill a series of holes through the pipe and use a Dremel cut-off disc to cut the remaining metal out to form a slot. You need to make this wide enough that you can fit the flat file into it and then file the slot smooth.

I thought this was going to be the hardest part of the build, but were pleasantly surprised by how easy it was.

Step 4: Screw Shaft

Cut the head off the coach bolt and insert the bolt into the tool body, then mark where the pin needs to go. Remove the bolt and centre punch the mark and drill the hole through the bolt. I drilled the hole through the tapered end of the body at the same time.

Step 5: Make the Pins

I used a couple of old Allen Keys as the pins, I cut them to length with a grinder and then ground them until the were round and the correct diameter. These need to be a snug fit so they don't fall out.

I wish I had done this step differently, I only used the old Allen Wrenches because I didn't have anything else suitable. I was worried that if I used a nail it would bend. It took ages to grind the pins down to size, I recommend you find something the right size metal bar.

Step 6: Groove

You need to make a small groove in the end of the tapered body to hold the wire. I did this by holding the body in a vice and using a Dremel to make a small slot. You can notice I've got a drill bit through the bar to help visualise the alignment of the groove. Once the slot is cut you can use this to get the file started to carefully make the final groove.

Step 7: Make the Handle

Now cut the length of the larger bar and then mark the centre with a punch. Drill a small pilot hole and then a 7mm hole through the bar. Now clamp the bar in a vice and use the M8 tap to thread the hole. Lastly, clean up the bar on the grinder and bevel the ends so it's comfortable.

Step 8: Buff the Parts

This is an optional step but it's an easy way to make things look great. There's a lot of truth to the saying 'It will buff out', give everything a good polish up until it really shines and then apply a thin coat of oil to prevent rust.

Step 9: Assemble the Parts

Drive the pins through the threaded shaft and body of the tool, then install the washer and handle. You can now mark the threaded shaft to the final length. I removed the handle and replaced it with a nut, then cut the shaft to length. Now clean up the cut on the grinder and remove the nut to help clean off the thread.

Reinstall the handle and you are done.

Now print out the handy instructions to keep with your new tool and enjoy clamping stuff reliably.