some homemade tools - pin wrench and floor scraper

The PC is now working (sorta) - the original motherboard died and took with it 2 of the hard-drives. A substitute motherboard was sourced on Ebay which should have taken the existing memory, CPU, graphics card etc... The motherboard was brand new, but over 5 years old. Basically it didn't last too long - failed in a different way and I was fighting a losing battle trying to repair this "on the cheap"
The "new" PC is simply a new motherboard ("Mainboard" as I was told by the sales guy) with new CPU, RAM and this also entailed a new OS since I exceeded the 4Gb of memory. I still have a few teething problems with my PCI SATA2 card, but I am working on it.

This article covers a few things I had to build during the outage on the PC.

Super Scraper
First is a tool for chipping cement off a concrete floor. There are floor scrapers available to taking plaster off floors, but this tool will remove tiles, cement, lino, cats, whatever you point it at. The secret to this tool is the heavy duty blade, coupled with it's weight.


Figure 1 - The super scraper leaning against the shed door

The blade is a bricklayer's bolster - a broad "chisel" which can be picked up in the discount tool stores for around $15. the bolster is modified by removing any rubber handle/covering, and then welding the handle to/inside a pipe handle of around 1500-1800mm (5-6') long. I deliberately choose heavy walled pipe for this job since you want a fair bit of weight in the tool. Since this one was made away from my scrap pile, a short length of thicker pipe was used to form a socket, and then a slightly thinner pipe was inserted to achieve the desired length.




Figure 2 - The head of the "super scraper"

The tool is used by simply sliding/ "driving" it along the concrete floor at an angle of around 45 degrees s the blade skims along the floor and the weight carves the "stuff" off the floor. A nice touch is to close in the other end of the pipe handle so there is no chance of cuts on any burrs or edges. It seems to self-sharpen as it wears on the concrete, but the bolsters tend to be pretty tough and don't wear that quick. This one was made to help a friend remove the leveling cement from under the tiles in his kitchen renovation. Prior to handing it to him, it was tested on the apron of my brother's shed where it removed lumps and cement dags with hardly any exertion.


Grinder Spanners

Another tool I had to make was some replacement wrenches for an OLD 9" (230mm) angle grinder. This grinder is an heirloom, and is so old it doesn't have spindle locks or any form of softstart. This means the spindle torques up really fast, and this seizes the retaining  piece on. I modified an old 7" pin wrench and 17mm spanner to undo the retainer in the past, but during some work the retainer became so tight the pinwrench failed during attempts to undo it.



Figure 3 - old wrenches alongside new wrenches - the ruler is 300mm (12") long


Figure 4 - old wrenches which failed

I made a new pin wrench using 1/4 x 1 1/4" flat bar with some grade 8 bolts filed down to make the pins. (4.6mm diameter on 28.1mm centres) The handle to this new pin wrench is twice as long as the original and once used the cheap modified 17mm spanner started bending. More scrap steel and I made a heavy duty 17mm spindle spanner.




Figure 5 - bolts used to provide pins in pin-wrench


Bonus Shop Tip - Cigarette Lighter Parts



Figure 6 - Disposable lighter found on road - cracked and empty

I walk the dog each day and often find discarded broken cigarette lighters. I usually pick them up and take them home to pull apart. What's worth having in a cigarette lighter?



Figure 7 - parts inside a disposable cigarette lighter

There is 2 springs and a "jet" which can be useful. The springs are a useful size for making detents in small tools, and the longer flint propelling spring is a size which is sometimes found in rifle ejectors. I've only started collecting the jets since I figure I can use them to solder into larger brass pieces instead of trying to drill such a tiny hole - useful for a burner in my project list.

Next articles will be the construction of the lathe stand.

Grabby & Squeezy - Hands part 2

This page covers the shrouds of the hands, and fixing the hands to Bender's arms.

The shrouds are simple conical transitions. From my interests in model rocketry, I had a tool called VCP (Visual Centre of Pressure) which contains a simple little utility for generating the development of a conical transition on paper. I used the package to develop the template for the hand shroud using the arm diameter at one end, the flared diameter at the other end, and the length of the transition being set to the height I choose (83mm to match the arm diameter, but then padded the number out to 95 so I had room to adjust things during construction).
The resulting VCP printout was then cutout, and traced onto the colourbond offcut shown above.
I added some extra depth at the narrow end of the conical section for retaining tabs, and proceeded to cut out the shape.

The first shroud has been cut out, and rolled, the second one hasn't been cut yet. Rolling the colourbond would have been easy if I had some sliprolls, but I don't. I simply clamped some pipe to the benchtop, and pulled the colourbond piece through and manually forced the curve into the metal. I repeated the bending a few times to tighten the curve, then clamped, drilled, and pop-riveted the shroud together.

This picture shows the tabs I cut for retaining the shroud. Knowing the shroud can't move towards Bender's fingers due to the conical shape, I wanted to retain the rear of the shroud by pinching it in the wrist joint. I know if I'd measured and marked everything to the highest degree of accuracy, it wouldn't be necessary, but knowing my welding, the slightest warp would have betrayed the joint, it was easier to make the shroud retained against the joint for a seamless fit.

The photo above shows one shroud fitted to one hand, the second (right) as the two pieces. A small slot was ground into the wrist plate to provide clearance for the pop rivet. All rivets were beaten down flush with the sheetmetal to reduce the protrusion, then later tidied up with bog.


The hand is attached to the arm via the captive retaining bolt in the wrist plate. Prior to welding the spacer pipe into the plates, the bolt head was modified so a screwdriver could be used through the access hole to turn the bolt. The one bolt holds the hand in place, and positioning of the hand is accomplished by loosening the bolt, rotating the hand to a suitable angle, then re-tightening the bolt.

When the bolt is tight, the shroud to wrist seam disappears. There is a small step in the diameters at the seam, but that will be disguised when the painting occurs.


Since I was out of "Ole Fortran" beer, I had to make do with one of the drinks favoured in this area. The Lemon-Lime SOLO is a nice drink, and I can see why the guys in the workshop prefer it on hot days (Isn't that everyday around here?) I know I got addicted to them after one shutdown, so now I try and limit myself to only one can per day.

So what haven't I covered yet? Still to come; antenna, head, eyes, and then painting.

Bender's Arms

The arms were made from the same size pipe as the legs, but needed a significantly more aggressive curve coming out from the shoulder. I marked up the 12,2,and 10 o'clock line as I did with the legs, but placed the cut lines closer in the are with the tightest curve. When I cut the 300 degree segments, I cut them wider by using the 2.5mm wheel, and making distinct V cuts, instead of simple straight cuts. The cut, but not bent, arms are shown on the welding table.


The welding table will be the subject of a page in the future, I'm rather pleased with how it turned out.


A closeup of the cuts showing the V cuts in the 300 degree segment. As I bent the pipe I had to tweak these cuts here and there to get the tighter curve for the upper arm.

As with the legs, I omitted to photograph the welding process, but it basically was grind out the cuts to remove the surface rust, then weld the cuts closed, and fill the open cut on the 60 degree segment cuts. The welded arms are seen laying on the ground in the last photo in the legs pages.

Now to make the shoulder/arm joints...

These shapes were made in the 4mm sheet I'd used everywhere else. The one on the left is the ellipse shape to match the arm pipe when cut at 45 degrees, the one on the right was welded into the shoulder joint (see the body page for this). The central bolt will be used for retaining the arm, and the smaller bolt will engage with one of the eight radial holes to lock the arm in one of eight positions. The photo shows the nuts I used to hold the bolt heads in place until they were welded in place from the back.

The above photo shows the ellipse plate welded to the arm pipe. I cut the arm at 45 degrees and then tack-welded the ellipse plate in place before grinding the closer fit, and then finishing the weld.
How did I mark the 45 degree cut on a the curved pipe? - A trick I read about used by blacksmiths was employed. I filled one of the quench buckets near the door with water to the brim, then carefully laid the pipe into the surface of the water so the waterline would mark the 45 degree line. Then I removed the pipe and highlighted the line with engineer's chalk. - The original blacksmith trick used coal dust floating on the water's surface to mark the line, but the rust on the pipe showed the line for me.

The "nut" on the central bolt was whipped up by welding a short length of 3/4" pipe to the nut, and then slotting the end for a scrap of sheet. A few tack welds and I have a long-reach wing-nut.
The photo below shows the wing-nut being used from inside the body to hold the arm in place at the shoulder joint.


A progress photo of the arms and legs attached. The arms were later shortened since I had deliberately made them longer than needed until I finalised the design for Bender's hands.



Next... Grabby and Squeezy - a.k.a Bender's hands

Bender's foundations - feet, legs, base - part 2

Once the pipe for the legs was cut and curved, I welded the cuts and welded the legs to the foot cups on the base. I didn't think to photograph it, but the next step was marking the top of the legs to be level with the base, and at the appropriate height. To do this marking, I used the trick used by cabinet makers, (and dressmakers) of using a block of "stuff" with a pointer and marker contacting the legs, and then rotated everything around to completely mark the legs. In this case the block of "stuff" was the body previously made, packed to height with some pieces of timber.

Once the legs were trimmed to the correct height and level, I tested the fit with a plywood disk I used to test the body of roundness.

A photo of the "high tech" tool stand I used to keep the tools off the welding table whilst I was working. The three grinders proved quite useful since the 9" (230mm) grinder was used with the 2.2mm wheel, the 4.5" (115mm) with a standard grinding wheel, and the 5" (125mm) with the 1mm cutting disks. Yes, I used the faceshield and earmuffs... I value my eyesight and hearing, and see too many of my friends from industrial backgrounds with hearing loss from exposure to these kind of jobs.

The leg joint plate was made by placing an appropriate strip of sheet on top of the crotch plate and drilling all four clearance holes at once. I then marked through the curved (elliptical) ends of the legs, and split the strip with two tabs - one on each leg, both pointing towards the middle of the crotch plate. I then welded captive nuts, and bolts in the joint plates so each leg has one bolt, and one nut for securing it.

The welds were ground back and touched up prior to painting, but the above photo shows the captive bolt on the left, with a nut spun on, and another bolt spun into the captive nut on the right.
I choose a single bolt for each leg to make alignment during assembly easier, but I wanted the extra strength of two bolts, hence the second bolt added into the captive nut.

As always, I like to stack the pieces together to see how my progress is going. This what Bender looked like at the end of the day making the legs. It's obvious I had been picking at all parts of Bender instead of completing one part, and then another.
Until the next installment...