Tag Archives: Maintenance

Cutting Down Spears

Why would anyone want to cut down a spear? Ever had a tip snap off at the flopper hole? Bent a spear at the flopper on a long gun? Well now you should be able to recycle these old bits of steel for another gun and hopefully another fish. Other things you can do are add floppers to spears like those butterfly spears or change floppers from top to bottom. Whatever the reason you need to cut a spear down here’s how to do it.

First thing is spring steel spears are MUCH harder to drill and machine than spring stainless spears. But I haven’t come across a spear that I’ve never been able to drill…eventually. Particularly tough spears are the freedivers spring steel and the Rabitech spring steel spears. Rob Allen spears are fairly average to drill, Riffe are just as easy and Torres tuffs are like cutting butter.

The first part of chopping down the spear is getting the flopper off. This can be a little tricky depending on the manufacturer. Riffe spears are near impossible and you may as well buy a new flopper! Here is a freedivers spear in the vice ready for the flopper to be removed.
Now all you do is file off the rivet flush down with the flopper and tap it out with a centre punch. This doesn’t always work so you may have to flip it over and file down the other side and punch it out that way. Either way after a bit of stuffing around you’ll end up with a spear with no flopper like so:

Now the next part is drilling the spear. If you’re taking off 10cm from the spear obviously put a nice big pen mark 10cm from the end. Now get the flopper and position it about 1cm behind this mark. Where the end of the flopper sits is where you want your hole. Always have a little bit more tip than the length of the flopper.

So no you know where you want to drill your hole how do you go about drilling through these hardened bits of spring steel? Well the first step is a drilling jig. All this does is keep the spear locked in place by the stainless screw and it has little hardened inserts to keep the drill bit in the centre of the spear. You should be able to buy something similar from a dive shop, if you have a lathe you can knock one up on the lunch break. I used bits of silver steel for the inserts, did all the machining and then hardened them. I have two drill hole sizes, 3/32” and 7/64”. I use the smaller one for 7mm spears and the bigger for 8mm spears.

Enough of the jig, here’s how you mark your spear. Place the mark where the hole needs to be on the little hole on the jig and mark another line so when you shove the spear up the guts you know where to stop!
Now don’t go tightening the spear in the jig just yet. You may want to line the spear up so your flopper goes straight up and down (yes I’ve had them come out at 90° before!) I use a little bit of stainless or nail or whatever to make sure the spear hole in the back of the spear is vertical, THEN tighten the jig so your flopper hole will be up and down. Seems obvious but I’ve done it a few times!

Now to drill these spears I use a Formula Cobalt drill bit in the 3/32” or 7/64”. You will also need some cutting compound. You may get away without for stainless spears but with spring steel ones forget it. This is what I use, ‘Rocol’ it’s a brown turd coloured paste but it works a treat.
Another compound to use is ‘Molycut’ but it’s a liquid stuff. Either will work fine and make drilling a breeze. So set your bit up in a drill press and make sure you put a nice smear of cutting compound on the bit. Use the slowest speed possible on the drill. Don’t be tempted into “going faster means finished faster!” You won’t get anywhere. If you want to use a hand drill you can try but you will probably snap a few drill bits. A drill press is the way to go with lots a downward pressure and remember SLOW!

Once you’re through take the spear out of the jig and viola! If you can’t get through the spear which will happen on the odd freedivers spear try a new drill bit. If that doesn’t work you may have to heat up the area to be drill cherry red and then let it cool and then drill. After drilling put the temper back into the spear as follows below. Only do this as a last resort.

You should run over the drill hole with a larger drill bit to sort of counter sink it to get the burrs off. The next part of the whole process is putting a tip back on the spear. Lucky with spring steel spears they can be re-tempered which means ANGLE GRINDER. You don’t have to worry about getting it red hot because it’s going to happen down the track anyways. So go nuts and put that tri-cut back on the tip. Work one edge at a time to get a basic shape and the angles right. A few minutes later and you will end up with a nice tip like so. You will get better and better doing these tri-cuts so if the first couple turn out a little less appealing than the mother in law don’t fret, just practice on some old spears. A file isn’t really necessary after a while but it will help to clean the tip up a bit.

Note; only go hard out with the grinder on spring steel spears, on stainless try not to get it discoloured or red because you can’t put the temper back into them. It will take a while longer but then again they aren’t as hard as spring steel spears.

Now to put the temper back into the tip of the spear so it’s not soft as butter. Simply rip out that blowtorch from all those prangers you’ve been making and heat the tip up cherry red. Once it’s all hot plough it into a jar of oil. Any oil will work; I used the old stuff out of my car so it’s not critical! Don’t use water or you will cool it down too fast and the spear will be too brittle. A little smoke and smell here is normal.
Now we are back to where we almost started a spear without a flopper. Pinning floppers is an art in itself which needs to be practiced or shown. For a flopper pin I find a snap clip works a treat. Don’t be tempted to use nails or what not the pin needs to be pretty hard stainless. Some brands of spears use 316 pins and the floppers stuff up very quickly as the pin bends out of shape. Snap clips and shark clips are made from high tensile spring stainless steel and do the job perfectly, never had an issue with them. You can also use proper flopper pins from a dive shop. Snap clips fit perfectly in the 3/32” holes, bigger shark clips work well for the 7/64” holes. Use some bolt cutters to snip off a bit about 2.5mm wider than the flopper. Also check to make sure the flopper is on the bottom (yes that’s happened to me before as well!)
Now you will need an anvil of some description, a vice jaw works okay but I have a bit of railway track that’s perfect for it. Using a ball pin hammer gently rivet over one side.

Don’t go bashing it too hard and try to get it as around and wide as possible. Repeat for the other side. You have probably got a flopper that’s pretty stiff or something wrong with it. Not too worry this can be fixed! For a stiff flopper usually forcing a bit of 8mm stainless into it to make it wider will do the trick:
This should make the flopper swing open and close willy nilly. If not try some 10mm stainless or get the pliers out and wiggle it around, you should be able to pick the points of friction making it stiff. So assuming your flopper is nice and loose gently tap this area down with a hammer:
This hopefully will make the flopper swing open to about 30° and then lock open the rest of the way.
The best way to tell if a flopper is tuned properly is to put the spear in a gun and hold it upside down so the flopper is sitting down on the spear. Give the gun a sharp smack with your palm and the flopper should flick all the way open and stay there. That’s how a perfect flopper should be.

So now you have a perfectly working spear that can take down another few fish. This is particularly handy if you have all the same brand gun and you bend a spear on your 1400 and then just cut it down for a spare 900 gun spear. You can also put two floppers on spears if you’re keen. Also now you blokes should be able to put floppers on threaded shafts so you can have cool looking spears with prangers or points for comps!