Hot Glue Insulation Block

Insulating wires that you have soldered together is pretty important, heat shrink is great but not always the best choice. Using this Insulation Block will allow you to inject hot glue around your join to keep it protected.

Flat steel bar (aluminium would be easier)

• A couple of nails
• Drill
• Bench Grinder
• Angle Grinder with cutting disc

Flatten the metal bar on a grinding belt to make sure the surfaces are polished. Now measure and cut two 50mm lengths of the bar, use the grinder to smooth out the ends.

Mark and centre punch two holes in opposite corners of the block. Now use a 3mm drill bit to drill a hole through both blocks while they are clamped together.

Now cut off two lengths of a 3-inch nail, hold the nail in the drill and use some sandpaper or a file to polish one end so it can fit into the 3mm hole easily. The other end of the nail needs to be a tight fit. Now use a hammer to tap the nails through one block, you only want about 3mm poking out the other side.

Lastly, grind the back of the pins off so the outside is flush. Make sure the two halves fit together perfectly.

If the metal bar is too wide like mine, now is the time to trim it down to a smaller size. Since the two halves are pinned so they won't move you can grind all the sides so everything is nice and flush.

Clamp both halves together for this step, and using a ruler and scribing tool mark the centre of one end of the block by scribing a line from corner to corner. Centre punch the centre and drill a 3mm hole from end to end.

This is a bit of a pain as it can take a little while to drill this all out, if you use aluminium for the block this step will be a lot easier as the aluminium is a lot softer than steel.

Anyway, to bore out the cavity open the block up and scribe two lines about 10mm each from the centre (20mm apart). With the diameter of the drill bit we are using this will give a 28mm long cavity.

Either clamp the block or use a drill vice and set the drill depth to 4-5mm. Now drill a hole on each of the marked lines, then proceed to drill out all the metal between the two outer holes to make a long cavity. You could also use a hand drill and dremel to machine this out if you don't have a drill press. If you are lucky enough to have access to a milling machine then ignore everything I said and use that.

One you have completed one half you need to do the same on the other side.

Clean off both parts and then clamp them back together, along the long edge mark the centre by once again scribing from corner to corner. Centre punch this to stop the drill bit wandering and drill a 4mm hole, be careful to only drill this half way through the block. Once the drill goes into the cavity stop drilling!

I then used a 7mm drill bit to enlarge the opening of the glue hole, this only needs to be drilled a few millimetres deep.

There are likely metal burs on the middle surfaces, using a small file quickly polish these surfaces up so both sides fit back together snugly.

The last thing to do is to give everything a little tidy up, either using the grinder or a file carefully put a small bevel on all of the corners to remove any shape edges.

You are now ready to use the Insulation Block!

You need to prime the block with a release agent to stop the Hot Glue from sticking to it, a small squirt of any oil will work, I used cooking oil.

Put the wire joint that you need insulating inside one half of the block making sure the joint is centred, then close the block up and use a small quick clamp to hold it together.

Make sure your hot glue gun has fully heated up and quickly fill the cavity up from the glue hole and wait a little while for it to cool.

Remove the clamp and open the block, you will need to remove the sprue with some wire cutters or a knife. The joint is now fully insulated.

You can get coloured hot glue, but I didn't have any. I will be ordering some coloured glue to match the wires in the future.