Bolt cutter repairs

Bolt cutters, aka "The keys to the city"

Long story short, I bought these ages ago - a generic set of 900mm (36") bolt cutters with a nominal capacity of 3/8". I bought them for cutting up expanded aluminium to drop in the furnace for melting.
I loaned them out so someone could cut up some 1/4" and 3/8" reinforcing rod, and there was a hard spot in one of the 3/8" rods - the paper thin handles didn't stand up to the use and tore.

So as a result, I had to repair this tool. I cut the remaining handle piece from the head castings by careful use of a sharp cold chisel. I tested the other handle by trying to cut some 3/8" rod
and a temporary handle, it failed as well - most likely find the other handle was weakened, but not visually damaged.


I tested some of the pipe sizes in my rack and found a couple which gave good slip fits, with wall thicknesses around the 2-3mm mark.
I made some replacement handles about 8" (200mm) longer than the originals, drilled some 11mm holes and welded some 10mm nuts on so some 10mm bolts can be used to retain the pipe handles onto the head castings.

I painted the pipe handles up since they wouldn't be used too often.

Once the replacement handles were made, I built up a "tool" to hide in the end of one handle. Made from 25x6mm (1" x 1/4") flat bar, the tool serves two purposes...

a - open ended spanner to tighten/ loosen the 10mm bolts

b - a 3/8" slot to serve as a "go-no go" gauge for testing material to be cut.


Removing the tool from it's storage in the handle end.


Testing the spanner on the retaining bolts

a piece of 3/8" rod passing the "go" gauge.... compared to

a piece of 1/2" reinforcing rod failing the "no-go" gauge.

I've since loaned the colt cutters back to the guy so he could finish his job, and it worked well.

welding cart

The welding cart was built to overcome the issue of always working on the ground. For some tasks, the cart is not suitable, and the welder is removed from the cart, and taken to the job, or the cart is simply left near the job, but the earth lead is disconnected from the cart, and clamped to the job.
The welding cart offers another advantage - one of a "large earth"... All my welding experience up until I built the cart was based on attaching the "earth clamp" to the piece being welded. Sounds good, but sometimes it's easier said than done. I had seen other people clamp to a large sheet of steel, then drop delicate work on the sheet, and use it's contact with the sheet as the return path. The entire cart is like that sheet of steel. The return clamp is attached to the cart (in my case by the clamp being attached to a tab on the underside of the table) so anything I place on the top of the table can become part of the current path, simply by it's electrical contact. This simplifies any delicate work considerably, and allows repositioning without fighting with the return lead.

I'll talk more about the welder itself in another page, but it has been considerably modified to make it more usable for the kind of things I want to do with it.

The cart was made from salvaged materials. Most of the sheet metal was cut from a discarded instrumentation cabinet. the steel is all 1.5mm (about 1/16") thick, and was powder coated/enamelled. The cabinet was basically cut so the top and bottom portions became the top and bottom of the cart, but the sides were replaced with other material.
The main structural components (frame, uprights, etc) were made from a rolled shape which I got from the tip. The cross-section resembles a squared up letter C, and it came in lengths of 1200mm (4') with grey paint on it. I believe it was some kind of packing material for shipping motorcycles, but I really can't be sure. The steel is 2mm thick, and the C shape is basically 30-35mm wide, and 19mm (3/4") deep. The slot on the open side of the C is 10mm (3/8"), and a 3/4" square tube will ride inside the C section if one corner is protruding through the slot (I used this exact concept to make the leaf folding mechanism)


Construction was basically determining the finished height, and then making up the side frames to that height with the top member equal to the width of the cabinet top.
The frames were welded to the top and bottom pieces, and some cross pieces were cut and welded in to form a "shelf" in the middle.

The middle shelf does not extend across the entire width of the table, since I determined it would be prudent to have the full depth of the table available on one side for hanging cables. Additional cross beams were cut and welded in to form the sidewall of the middle shelf, and some hooks were welded in on these beams for hanging cables.


The original build on this cart had four wheels, one at each corner, but within a very short time, I determined was troublesome - firstly for the issue of uneven ground, but mostly since the cart would move under the forces of grinding, or other metal abuse activities. The front wheels were cut off, and some 3/8" nuts were welded into the front pillars. Some 4" long cup-head bolts were screwed into these nuts, the heads of the bolts forming the feet for the front of the cart. A telescoping handle was added into the shelf beams, to assist in lifting and moving the front of the loaded cart. The telescoping handle is nothing more than a piece of the C section steel tubing, with another piece of 3/4" square tubing inside it, some stops welded in, and a "handle" to make it easy to pull out.

The telescoping handle can be seen just above the top PVC tube, extended out approximately 6"

The top of the bare cabinet was about 400mmW x 500mmD, and adding the widths of the two support frames either side only added another 70mm to the overall width - not nearly enough room for any serious fabrication. A means of making the table top larger was required.
One of the cut away sides was stiffened up by welding a piece of "C" tubing at each end, the original folded edges were sufficient for the sides since the folds were 3/8" deep, and 3/8" wide, 3 sides of a perfect square.
Some hinges were padded out, and screwed in place for the drop leaf, and the salvaged rear axle of a dumped lawn mower was used for the hinge of the brace. The ends of the axle were trapped in some short pieces of 3/4" square tubing which was tacked under the sheet metal leaf.

Photo taken from underneath the raised leaf, showing the brace, vertical track, and it's joints.

The other end of the brace is bolted to a "shuttle" which runs in a vertical track. The shuttle is nothing more than a piece of square tubing running in another piece of C tubing, with a tab welded to it for the brace to bolt onto.
When the leaf is dropped, the shuttle is in the bottom of the c section track, but when the leaf is lifted into position, the shuttle moves upward, and trips a weighted pawl which prevents the shuttle returning past it. This pawl keeps the lifted leaf in the "up" position, level with the permanent table top. The pawl is released via a lever at ground level which can be activated by the operator's foot.

The locking pawl as viewed from under the shelf. The release mechanism, and counterweight is operated through the 3/8" rod which acts as an axle for the pawl. All joints are simple clearance holes through scrap steel, nothing fancy.
Top photo - leaf lowered

Photo of leaf raised


The welding cart has evolved a little over time, the middle shelf had some lengths of PVC pipe added for providing storage for welding rods (2.5mm and 3.2mm), and a block of wood with some holes drilled through it was added for holding the "live" electrode (handpiece) in an insulated holder so I could put the handpiece down during a job, and not worry about current flowing (the lesson on that effect was most uncomfortable).

The 3/8" cup head bolts failed recently (see Hose suspenders page) when I wheeled the cart out in the street so I had enough room to turn a 4m (12') length of 3/8" square rod through a jig clamped atop the welding cart. It was during the repairs that these photos were taken. The 3/8" bolts, and nuts were removed, and replaced with some 20mm (~3/4") anchors and nuts. I don't know what the anchors were for (part of a toolbox full of junk which I found on the side of the road - it's amazing what falls off trucks around here), but it's nice to use some of them up.


That's about it - I know I took better photos during the construction of the cart, but I don't seem to be able to find them. I know the cart looks rough, and I'm really not in the mindset to go nuts painting things like this when all they do is get dragged between the shed, and the job. I paint things which will spend more time "sitting" than working, unless painting is needed to protect the "thing" - given this cart is my biggest workhorse, I don't see the point painting it. If fact, I have to periodically run the grinder over the top every month or two to remove any rust, or paint which would stop the current flowing through the top and whatever workpiece is on it.

A lot of what was built when I first set up here was built from scrap I collected from friends at work, and the local tip (Salvage). I'd just moved to start this job, and disposed of all my building materials for the move. You will find a lot of what I describe and show in these pages will be made from salvage/ surplus materials. Some if it is my desire to save money, most of it my desire to reuse materials, and find uses for "junk". I read shop notes books from the 1900's for fun, and do not subscribe to the throw away mindset that many others have.

Foundry "Robot" - part 3

The controls for the robot are all located at the operator end of the device. The controls primarily comprise a pair of handles at 90 degrees to each other for swinging, turning, and moving the main beam (3m (10') pipe) through the spigot, tilt, and sleeve joints. The two handles are attached to the beam via a sleeve which is pinned to the beam with a thumbscrew. This allows the handles to be moved if the operator prefers a clockwise pour, or anticlockwise pour.
The end of the pipe beam is left exposed, and open to permit the future (possible) addition of counterweights should they prove necessary, although as yet they haven't, even when the robot was used with 5L of lead used to deaden a homemade anvil.

The control for the gripper is a simple push-rod which activates through a handle located at the operator end. At the gripper end, the push rod operates a slug which is linked to the gripper bell-cranks, whereas at the operator end, the push rod is connected to a handle which can be locked at any point of it's operating range.

In the above photo, the gripper control handle is back, towards the operator, and the grippers would be open. The arc shaped plate (quadrant) is actually the remains of a 9Kg (20lb) Propane cylinder top, left over from making a "George Vortone Muller".
The quadrant has a series of cuts in the edge made with the cutoff wheel of an angle-grinder. The lever at the top of the operating handle lifts a locking bar which engages with those cuts - similar to the rachet and pawl mechanism in a handbrake.
In operation, the user grips the crucible by squeezing the lever, and then pushing the handle forward to close the gripper. Once the crucible is gripped, the lever is released and the handle stays in that position. A small amount of "spring" is in the system to permit minor positioning errors in the cuts on the quadrant.

The above photo shows the griper control in the closed position.


The next sequence of photos shows the approach of the gripper to the crucible
Then the nose piece locating on the tang
and then the gripper closing on the crucible
At this point, the crucible can be picked up, and moved through all the axes of movement the robot offers, including pouring...


That pretty much covers the robot.. I did find one misplaced photo of the gripper mechanism without the fingers bolted on - see below. It helps clarify what I was trying to say about the mechanism being separate from the fingers and nosepiece.


The main thing this robot forces me to do is lay out my foundry area properly. I am constrained
by the centre of rotation of the robot, and the reach of the beam, and sufficient area to work in. I found these constraints allowed me to divide my work area into three distinct "zones" - HOT, WARM and COLD.
Hot is where the furnace is - pretty self evident.
Warm is for molding, pouring, degassing, skimming, etc.
and Cold is for charging, or loading the crucible.





If I pickup the crucible from the cold area, and use the robot to load it into the furnace, then I am guaranteed that it will have it's pouring lip pointed where I want it for the pour.

The robot is tall enough to permit me to place metal on top of the furnace for preheat, but I only do that when necessary - which isn't often here.

So, to sum up... The robot offers the advantage of not needing any significant lifting, in fact the heavier the crucible, then easier it is since your own body weight can be used to counterbalance the load at the gripper.
The gripper can be modified by simple bolt on fingers, and nosepiece for different crucibles, or to replace corroded parts.
The robot encourages the layout of the foundry work area into zones based on tasks, and risks
The robot can be built from scrap, and is fairly intuitive to use.
The robot permits a single operator to load, pour, reload, etc crucibles up to A30 without the use of a second person, with enough accuracy in the pour to pour water into the neck of a 2L coke bottle, and only lose 100mL (5% loss pouring into a target of 3/4" diameter at 10' away.)

Foundry "Robot" - part 2

Following on from "part 1".. the tilting joint (located under the main sleeve joint) is comprised a small pipe/bar joint atop the spigot joint.
The photo below shows the pipe welded to the top of the spigot joint, and the two cheek pieces holding the bar...

Photos of tilt joint in action - from one extreme...

To the other extreme...
The dust cover was also shown is those photos protecting the sleeve joint, and it's bearing shells. There is also a carry handle visible - I put it there since when I first moved the robot, I'd let the spigot joint open, and carry the base as a separate piece form the top... now they are always together with a hook, which is disengaged after movement.

The gripper...
Basically I designed this to be fully adjustable. By changing the "fingers" I can change what it picks up.
The fingers have a full range of movement between two extremes, shown below...

Above was "fully open", now this is "mostly closed"...


I say "mostly" closed since the finger design prevents further movement, but the mechanism permits more movement.

The gripper consists of some major parts - all of which are visible in the photo above.

a - The actuator and bell cranks -square pipe at low left and flat bar bolted to it, up to and including the small plates which tilt between the pincers

b - bolt on "fingers" - held to the bell cranks via 2 of 1/4" bolts - the angle iron "pincer" shapes with the small length of flat bar at the end near the bell cranks

c - nose piece - it's the small piece of round pipe visible protruding from the end of the square pipe... the nose piece actually includes the last inch of square pipe (removable)

These components allow the gripper to work, and be modified to suit the crucibles in use. My pipe crucibles have a "tang" which I use to locate them, and the nose piece mates with that. If I use a ceramic crucible, the nose-piece is swapped for one resembling an up-side-down letter "L" which locates the top rim of the crucible, and the fingers are broader, and more curved.

The next part will show the controls, and a test drive of the robot

Bender's Head - eye shroud

The fiddliest bit of the project - the shroud which goes around Bender's eyes.
I first planned on building this part using slices of extinguisher and simply flattening the round section onto a mold/pattern/former, and then cutting and welding it on - sounded good in theory, but nearly impossible to do in practice without resorting to heavy equipment, or forging temperatures. - sorry no photos of that attempt - all evidence was taken to the tip months ago.

The second (and successful) attempt was to use a "built up" approach. I split some of the pipe I used for the arms and legs longitudinally, and inserted pieces of sheet in between the pipe halves to form up the shroud. In the photo below the two halves of a shroud are seen on the left, and a completed shroud on the right.

I didn't bother making the sheet the same length as the pipe halves since I knew the pipe had to go back to the centre line of Bender's head, where as the sheet did not. In the next photo the marking for the intersection with the head has been marked with a cheap whiteboard marker. (I grab the cheap ones whenever the discount store is in town - I use them for marking metal if I need to have contrast, or the ability to erase the lines (if on smooth metal) - I basically use whiteboard markers like chalk on rusty metal, or prussian blue on smooth. - I do use chalk as well, just whatever suits, or is within reach at the time)

The waste material is cut away, and the shrouds are ready for fitting to the heads.

A sharp observer will notice I have not cut the corners at the back of the shroud too accurately, and have instead commenced thinning the metal from the inside. Knowing the pipe has wall thickness of around 4mm (just under 3/16"), it knew a smooth transition would require the metal to be thinned considerably.

Fitting the shroud to the heads was fairly straightforward. I attached an eye-plate to the head, and then labeled one head "A", and the other "B". I then marked each shroud with a corresponding letter, and marked the top surface of the shroud so the shroud would always be placed on the same head, the same way up. I then worked around the seam touching up grinding, thinning, and contouring until the fit was less than 1mm (~1/16"). I also marked the head so the indestructible red paint could be ground away for the welding.

A note about the red paint... I don't know what NuSwift used, but that paint is amazing. It prevented rust for over 20 years, is hard to remove, and doesn't burn very well. In the welding photos a margin of only 1/2" can be seen between the weld, and the unburnt paint. I weld salvaged material a lot, and the epoxy paints favoured by local industry burns to a margin of at least 1" when I weld comparable thickness metals. The interior of the extinguishers had another paint inside which was pretty good at well... a thin grey paint which was found failed in only 3 of the 40 extinguishers I cut open.

Back to fitting the shrouds on...
Once fitted, the shrouds were welded in place (see photo below), and I then ground and rewelded to try and build a neat consistent fillet.
The fillet is just visible in the photo below. I placed the eyes on the plate, and bolted it in for testing the fit and look - perfect!!


The next thing to do was the liberal application of bog (automotive body putty - "bondo"), and a lot of sanding and general clean up of welds, fits, and general appearance.
I didn't take photos since the amount of dust generated from the process coated everything with a lovely dust, and I didn't want the camera filled with it.
My approach to the preparation for painting was to sand back all rust, and paint, and then apply a skim coat of bog, and then sand back so the surface was smooth. I predominantly used a flap wheel on my grinder for the aggressive work, and used files, knives, and sandpaper for the finer work.

Looking back, I know I missed a few spots here and there - I'll be the first to admit I simply wanted to get this project finished, and weighed the effort for perfection, versus the return on my time. As I said a few times to people, "it's a lawn ornament, not a show piece. I can always go back and strip him back to metal and refinish him if I change my mind."

Next article... painting. I'll discuss the colours I used, and masking the "fiddly bits"