Vike's Complete Guide to Building a Spyder Pump


Design of the Pump Marker

Milling the Body, cont. 


NOTE:  When using tools, be sure to follow ALL safety procedures.  If you are a minor, be sure to get parent permission first and have parental supervision.  Never leave equipment on and unattended, and be aware that while drill bits are very tough, they do tend to shatter when drilling on other metals.  Be sure to wear proper safety goggles and go slowly.


The slot that you cut in the side of the body must be carefully done.  You don't want to cut into the area where an oring has to seal because this will cause leaking.  You also don't want to cut too little out, because then you won't be able recock your marker. 


You should REALLY take your time doing this, and do a good job.  Remember, measure twice, cut once.  If you screw up, you can’t add the metal back!  Fortunately, until you get to the larger sized bits, you CAN adjust your cuts to make up for any previous mistakes.  But, be careful you don’t make the mistakes worse.  Lower the drill VERY slowly – this will be easier on the metal and the bit, and make it to where you don’t have to file so much later on.


I got lucky again because the side cocking striker of my marker gave me a clue as to where I wanted to cut the slot. 


Note:  In a side cocking marker, the pin to recock the striker lines up with the pin that connects the striker and bolt. 


Since I was using the original grub screw hole that holds the connecting pin in, this was the perfect tool for letting me know just where to make my marks.  With the marker decocked, I used a sharpie to mark where I wanted to start my milling.  Then I recocked the marker, and made a mark where the cocking pin hole was again.



I didn't take pictures prior to milling the slot, but here you can see where the pin hole in the striker (bottom) lines up with the pin hole in the bolt (top).  I marked the top tube where the striker pin hole in the bottom tube was, then did the same with it cocked.   

You notice that the top slot is a bit longer than the where the actual pin hole stops.  I found that when I tried to cock the marker, I needed to go a bit further to allow the sear to engage the striker.


Step by step guide to cutting


1.  Once you've made your marks, use the straight edge to draw a line between the two marks down the center of the top tube.  This is where you're going to mill.


2.  Line up the body with the bit in the center of the line.  Take your 2 X 4 and set it against the body.  Now measure from the edge of the wood to the edge of the drill table.  Make sure it is equal on both sides and clamp it down TIGHT.  Then check the bit on the line again to make sure you didn’t move it any.


3.  Using a smaller drill bit, drill a series of holes along the line you drew, close enough to almost be touching, but not quite.  As you raise the drill bit sizes, these holes will end up overlapping.  NOTE:  You DON’T want to start your first hole directly on the line!  You should start slightly back from the starting point as with each larger bit, the metal will be cut away closer and closer to that line. 


4.  I used several sizes of bits, all the way up to 3/8”.  I didn't want a large slot hole, but I didn't want to take a chance on the pump rod binding up, either.  This seemed to be the correct size for that.  Make sure to constantly check that you’re staying in the center of the body.  Once you get all the holes drilled, you can go back and take out all the little pieces with the bit until the bit can move back and forth without hanging up anywhere.  It should look something like this (the top slot, though the bottom slot is what you're striving for):


  Unfortunately, I messed up just a little bit towards the back of the slot.  However, it's these little things that make the marker more personable!  (At least that's what I'm telling myself...)  It's not very noticeable with the pump arm attached.


5.  When you finish with the drilling, remove the body from the drill press and clamp it in the vice (make sure to use cardboard or leather between the body and the vice to prevent scratches).  Use the small files to smooth the pits and rough edges of the cuts.  Take your time and do a good job.  I rounded the edges a bit to make them safer and not quite so sharp.  Use flat files with harsher teeth to remove a lot of material, but be aware you’ll change the size of the slot.  Use the less harsh edges to smooth them out, then use the round files to hit the rounded areas of the cut.  Finally, hit it with some sandpaper – first lower grit like 660 and move up through 1000 grit paper.