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.

Taig Lathe Cabinet - Motor Mount and unloader

I'll start documenting the build of the lathe cabinet using those photos still on the card in the camera (the other photos will have to wait until after the PC is rebuilt)

The Motor Mount
The original lathe stand used a jackshaft mounted on a wooden slide-way for a clutch, and speed control was limited to the cone pulleys on the motor/jackshaft - and then the standard Taig 6 speed cone pulley.

The new motor system would have the motor speed controlled by a VSD (Variable speed drive) giving infinite speed control over the range of 0-100%.
I still wanted a clutch (unloader) so I looked at various designs used by others and cobbled up a version of my own.

The belt tension aspect of the motor mount is loosely based on a design shown on Nick Carter's website. (www.cartertools.com)
His design uses rods for alignment, and a threaded rod for adjusting the position of the moving member. My design uses slots cut in the mount for alignment, and a threaded rod for adjustment.
The basic structure is made of two pieces of 50x50x3mm angle iron (2" x2" x1/8") welded together to make a channel 100mm wide and 50mm deep (4"W x 2"D). the length of the pieces is approx 200mm (8")

I then cut 2 pieces of 50x50x3mm angle iron at around 300mm (12") long and cut slots about 12mm (1/2") from one edge. The slots were a clearance fit on standard 6mm bolts. (Slots were cut using drills to mark the ends, then 1mm cutting disc in between)

Corresponding holes were drilled in the piece made earlier in the description, and 20mm (3/4") bolts were tacked into place so the threads extended out through the slots.
End pieces were measured and made up to close out the end of the longer pieces, as much for stability, but also to support the threaded rod used for the adjustment.
The moving part is driven by a nut which was threaded in, and then tack welded to the underside of the moving part.Nuts spun on to the threaded rod, and welded in place became the thrust surfaces for the rod's action, and one nut was welded in place out the front of the unit for adjustment purposes.



Figure 1 - base of motor mount - sliding parts.

The pieces already described do not actually mount the motor, instead they provide a base which can be adjusted. The part which actually supports the motor is a hinged channel (cut from the side of some 100x100x3mm square tubing) so it actually 100mmwide, and 15mm deep.
A corresponding piece is fabricated from 4mm plate to sit atop the moving motor mount part made earlier, and to support the channel piece just described. The channel piece supports the motor by means of 2 slots cut in the channel at right angles to it's long axis - these permit adjustment of the motor position along it's shaft axis.

The channel is hinged onto the mount plate, and a cam is placed near the mount hinge to change the angle of the channel. The cam was built by cutting an approximate shape from 4mm sheet, then  tack-welding a 15mm wide strip of sheet around the cam surface for wear reduction. The cam has a position where the "lifting effect" is stopped - this is the position where the motor is tilted back away from the headstock of the lathe.


Figure 2 - the built up cam which tilts the motor mount channel.


So the overall structure is:
the motor tilts forward and backward within a range of motion governed by a cam (35mm = 1 1/2")
which sits atop a sliding mechanism which adjusts belt tension over a range of 75mm (3")
The motor can also move along it's shaft axis by 25mm (1") via the slots its mounted in.

The cam is operated by a wire lever about 250mm (10") long located well out of the way on the LHS of the cabinet.


Figure 3 - completed motor mount assembly

A standard steel ruler pinched under one of the slide nuts was used to test the range of the tilt mechanism



Figure 4 - Motor mount system in the unloaded (belt tension released) position.

The recorded range of motion was approximately 35mm (1 1/2") between unloaded (no tension) to the loaded (tensioned) position.



Figure 5 - Motor Mount in the loaded (tensioned) position.

Why have the facility to drop belt tension via the lever?
#1 - ability to leave the lathe when not in use with the belt un-tensioned to prolong belt life
#2 - easier changing of positions of the belt on the 6 speed pulleys
#3 - less chance of driving the motor when moving the spindle by hand (new motor is a PM DC motor which would act like a generator if I spin the chuck by hand)

So based on this design whenever I change the belt, I would place the belt on the appropriate pulley range and push the lever up into the "loaded" position.
I would then use a 17mm socket to adjust the threaded rod and move the sliding part so the belt tension was where I wanted it.
Then I would use the lever to reduce the loading, and adjust speed ranges accordingly.

In testing, I have found the flat section on the cam is sufficient - I can "feel" it click in through the handle, and the tension stays constant during use.


Next couple of posts:
I have photos of the frame construction, basic sheet metal work, and the construction of the control panel i can access. It doesn't cover much of the control electrical system, but does cover the fabrication of the switches, and the panel-work itself.

Taig lathe cabinet - completed

Today I took advantage of some time away from work during the public holiday to bolt the Taig lathe to the new stand.

Some history...

Figure 1 - original lathe stand

I bought the original Taig lathe from an amateur pyrotechnician in Brisbane in 2001 (or was it 2000?) The motor which came with it was a salvaged unit from a washing machine.


I modified the motor mount to retain the pillow block and 1/2" shaft, but mounted the motor and jackshaft on a set of sliding mounts which gave me a clutch in the form of a "belt unloader".


Figure 2 - motor mount and jackshaft on sliding mechanism

I put a drawer underneath the 18mm (3/4") MDF top sheet and used it this way ever since. In the meanwhile a removalist broke the jackshaft mounts, the motor board started a gradual twist (compensated for by inserting popsticks under the motor mounting), and the bearings in the motor started to fail.


Figure 3 - tail stock view of old stand

The motor controls (on-off switch) is mounted in the front of the white icecream container screwed to the baseboard - inside the icecream container is the start capacitor and the wiring out to the motor. - real high tech.

Over the past 5 years I commenced modifying the lathe by adding a leadscrew and halfnuts, converting the tool post and tail stock socket screws to thumb bolts, and building accessories.



Figure 4 - the conversion of socket screws to thumb bolts

So after essentially 10 years, this 12-14 year old lathe is getting a new cabinet and drive

That was the past - now here is the future...

Figure 5 - the new cabinet with Taig lathe in place


Electrical highlights
300W DC PM motor driven via a PWM VSD (Pulse Width Modulated) (Variable Speed Drive)
NVR and E-stop safety circuitry (No-Volts Relay)
4 switched GPOs onboard


Powered from a single 240VAC IEC power cord


Figure 6 - electrical cabinet

Mechanical features
Metal cabinet with enough "meat" to permit drilling and tapping accessories anywhere I want.
Swarf tray with gate in floor
magnetic metal base for DTI, etc
motor mount has a "belt unloader"
All painted up in "Bender gray" except the 4mm thick metal baseplate

The motor mount is loosely based on the Nick Carter design, but modified for my purposes with a cam operated unloader mechanism.



Figure 7 - the motor mount in the "unloaded" position

The control panel represented an interesting amount of work which will be covered in greater detail later. one of the fun parts was the logos and labelling - the frustrating parts was doing the wiring to a suitable standard which permitted easy construction, and repairs.


Figure 8 - close up of control panel

In all, about one month's work over weekends, and the odd day here and there (mornings during shift rostered days.) - estimated total labour time would  be 100 hours
The wiring took about 3 days since I had to redo some of it when my neighbour offered some advice on how to make it better for someone else to fault find in.
Everything except the motor and some electrical components was either constructed, or salvaged - the out of pocket expenses were around $200, and a large chunk of that was for the power supply.

I will do up some articles which highlight the construction process, with focus on the various components/ skills, but in the mean time I'm going to enjoy using this "reborn" lathe.

Making some dolls houses (CBFT training aid)

My ERT trainer mentioned once that as part of Compartment Fire
Behaviour Theory (CFBT) training, we can observe the phenomenons
(neutral plane, pyrolysis, etc) in a training aid called a "dolls house".



Figure 1 - cutting up the chipboard

A dolls house is made of chipboard and is nominally 400 x 400 x 400 mm  in size with a door way cut in one side.
The plans called for 16mm chipboard, but all the local supplier had was 18mm - no difference, just means the internal volume will be slightly less... with thicker walls the burn may take more time before the house falls apart.

Basically I cut up 2 full sheets using a circular saw, and then nailed the pieces together to hold the bits together whilst the "liquid nails" (construction adhesive) set up.



Figure 2 - the doorway cut into strips which can later be broken up as cribbing


I cut up the left over pieces to make 6 small "tables" to simulate internal furniture, and the remaining timber was cut into small pieces to kindle the internal fire ( pieces called cribbing are all about 1/4" wide, and the full 18mm thick)



 
 Figure 3 - open door to dolls house with "ikea table" inside



I also had to make a stand to place the completed dolls house at around chest level. I had a cast iron base from a large industrial fan which I modified to take a base for the dollshouse.



Figure 4 - completed stand with base for dolls house

During the construction of the stand, I had to undo a bolt on the stand which was slightly rusted - when the nut/bolt rust finally broke free, the spanner spun through and crushed my ring finger splitting the nail from side to side. Hurt like blue blazes, and bled like nothing I've seen in ages. After a few hours the bleeding had stopped and this is what it looked like...



Figure 5 - injury to ring finger


Job done as delivered to the trainer.



Figure 6 - completed houses and stand


Next posting/s should be the completed taig lathe cabinet, and construction articles.

Taig Lathe Stand/Cabinet - introduction

The current project...
My Taig lathe has been residing on a sheet of 18mm MDF for the past 10 years. The sheet has a wooden drawer built in underneath it, and a clutch/ jackshaft system for speed control. I will put a photo up in this series of articles, but not yet, this post is more a "preview".

Basically the old base (lathe stand) works, but it has limitations and problems. Some of the problems are the result of a certain removalist, some the result of bad design on my part, and most are simply the result of cutting corners due to cost constraints. - whatever the reason, it's time to make things better.

I'll do up a series of articles covering the design and build (mechanical and electrical) later, but for now here's some progress photos and a brief note of some features...
Lathe stand/ cabinet features:
full length/width drip tray
2 lockable equipment drawers under the drip tray with full extension
removable swarf tray
swarf gate in drip tray for dumping swarf
removable back board
4 switched GPO's (power points) with MCB
adjustable motor mount with belt unloader (clutch)
fold in carry handles
magnetic base with enough thickness for tapping holes if needed.
enough room to permit/ support my planned projects (backgear, change-wheels, taper turning attachment, indicator bases)

Motor controls:
24VDC 500W PWM VSD with reversing switch
16-20A over current protection
NVR (No Volts Release) circuit with additional e-stop at tail stock end




Just  waiting on the postman to deliver a few parts and this job is finished. The VSD cabinet (LHS rectangular section) contains:
500W 24VDC PSU (courtesy surplus parts online)
6800uF capacitor from a Seimens VVVF (for smoothing)
125mm fan (with some trickery in the ducting) for forced cooling
PWM circuit (with heatsinking)
control switches (Start, Stop, Speed control, reversing switch)
IEC socket with filter

DIN mount rail containing -
16-20A SFKOL overload protection device
NHP Terasaki MCB for isolating all 240VAC circuits
Industry standard relay mount and relay for NVR circuit
The DIN mounted components are accessible through the front panel (for resetting, or fault finding)




Both drawers are accessed from the front, on ball bearing slides with full extension - no excuse to have things lost in the back of the drawer again.




The removable back board supports the electrical circuits, and a tray for storing things during work - a work light will be attached to this backboard as well.




The range of travel in the "unloader" mechanism is shown here (the distance between the shaft and the vertical steel ruler - about 35mm (1.5")). The adjustable motor mount is shown midway through it's 100mm (4") of travel.




A photo from the tailstock end of the cabinet showing the tray mounted on the backboard - the rectangular holes visible in the slanting face are for the GPOs. The tray has a false floor and is sealed so the GPOs and cabling are protected. The GPOs were mounted in this manner (downwards sloping face) to provide easy access, but also make it impossible for swarf or coolant to fall into the outlet holes.

The materials used is basically salvaged sheet metal - some 4mm gal sheet for the load bearing areas, and sign-white (colourbond) for the rest.
The frame is a hotch potch of 25x25x3 angle, and some 25x25x1.6 square tubing.
All sheet metal bending (that worked - see future postings) was done using metal clamping with judicious use of hammers, wood blocks, and muttered cussin'
Most of the electrical parts are salvaged, however the power supply, and PWM section are purchased/ built  - all other parts removed from salvaged equipment (even recycled some bus mounts from a switch board to make the drawer handles)

The techniques, design, and details will be covered once I get the main computer fixed (power outage cooked one of the bridges in the mobo - lost the O/S drive and a few other peripherals), and few other demands on me at this time

Next update will most likely be in two weeks time - the pictures are already taken, it's just time to type, format and upload.

shed PC cabinet, and electronics test gear

another set of projects!!! - Yes I know - got more than enough on my plate as it is, but it is related (see end of this post)

I needed a PC in the shed for programming work. Given the lack of space, the easiest thing to do was put the PC in a wheel-able cabinet, and packaged in such a way to permit it to be collapsed as small as possible.

I'd rescued an old 3M overhead projector a couple of years ago, and the wheeled stand it came on... This stand, with a few modifications, became the PC cabinet.

The original stand had a top which was set approx 6" (150mm) under the level of the top vertical posts, and the 2 flip out leaves attached to the posts. I raised the top shelf to line up with the posts, and then closed in the underside on 3 sides with some old sheet metal.  I took another piece of metal to work and bent it up to make a door for the fourth side.



The "front door" of the PC cabinet is the grey sheet of metal on the RHS of the picture - with black cloth tape covering the cut edges for hand protection.


The above photo shows the LHS leaf in the raised position - whereas the other photos in this article show both as lowered.

The PC is an antique (old celeron from memory) but it does what I need (runs the PICAXE suite of software). Network is accessible (if I run out the 15m patch lead) and the speakers, mouse and keyboard cabling is wrapped in a spiral wrap and pinned under the top shelf.

Currently (due to other projects) the most this PC does is play music for the shed area - the programming has been on hold for a few weeks now due to other commitments.




As part of the PICAXE work, I needed to rig up a 5VDC power supply for the breadboard and other circuit prototypes. Digging through my boxes of salvaged gear I found a near new 5VDC SMPSU. Using some scrap pexiglass, I fashioned up a board with the SMPSU encapsulated at the top. The scrap pexiglass had some bends in it already, and I used them to form the cover for the 240VAC section, and to mount the power switch.



It was a simple case of then bringing the 5VDC and COM rails out to the prototyping area by means of the terminal block. I also brought the mains Earth out as well. The colour code for the terminal positions is shown on the LHS of the cover.
LRF are applied on the bottom of the unit to stop the fixing screws from scratching up the top of the cabinet.







The unit fits nicely in the box with the other electronics bits.




Why PICAXE?
I needed something, and I was so out of date with my previous experience (6502, 8086, pic16f84) that I asked on the newsgroups what was the best to come back in with... the suggestions included Arduino and other systems, but PICAXE came through loud and clear as suited for what I'm trying to do...
I've a project to help someone who's eyesight is going. He's a machinist who's finding it hard to use a standard dividing head - I can't afford a "DivisionMaster" (excellent product designed by Tony Jeffree) so I'll try and build my own version (with several features not in the original - suited to the user's tasks) and bring my skills back up at the same time.
That is the story of my life so far - get an idea to do something, identify pre-requisite equipment and skills, acquire those, find there are more needed, etc ad nauseum.
Kinda the model engineer creed - "Build a jig to build a tool, to build a jig, to build a tool, to build a jig to build a project". In my case the lathe was bought to build a micro hybrid rocket motor, but the lathe needed parts so I started building parts, which meant I needed the furnace, which meant I needed to learn.... and on the story goes.
Don't take the above as a complaint - by the time I build that motor I'll have a fully equipped workshop, an amazing set of skills, and a very diverse set of experience - all I need is time... and patience... and space for junk... and money for bits...       :)

welding helmet renewal

I learned to weld (SMAW - aka Arc welding, aka "Stick welding") with a standard CIG "rockhide" full face helmet. You had to flip the helmet up and down to see whenever the arc wasn't running. Better than the handheld mask I used a few years later, but still painful to use compared to the newer "speed glass" style auto-tinting helmets. It's so much easier to weld when I can see the tip of the rod moving up to the point of the weld, instead of losing sight of it due to flipping the filter down

I bought a cheap helmet and used it for several years, and eventually it stopped working. Being the tinkerer that I am, I opened up the main unit and discovered a few things...

The helmet has a solar cell on it, and was advertised as never needing batteries since it charged from the sun. The batteries inside were 2 silver oxide non-chargeable button cells. My guess was that the solar cell reduced load on the batteries, but was never able to charge them. (Silver oxide batteries aren't rechargeable)

The other finding when I opened up the unit was that the nominal 6VDC across the 2 batteries was only 2.8VDC... I can hardly complain since they lasted seven years.




The rest of the circuitry is under the white "potting" used to protect the circuitry - I never disturbed that, just accessed the silver terminals which used to be spot welded to the original batteries.

Armed with that finding, I quickly fashioned up a 6VDC supply and connected it to the original battery leads (with the old battery removed) and tested the helmet - it worked.



The photo above shows the hole drilled through the back panel of the glass unit, and some flexible Cat5 cable led through for accessing the power terminals of the electronics.

A more permanent solution was made up...
The battery holders are from some cheap solar garden lights the dog broke
The cable is some flexible Cat5 patch cable
A number of holes were drilled in the helmet to affix the battery holders, and cabling.
All holes were then sealed over with some hot-melt glue, and painted over to block the UV from the welding operations.






Problems found with this solution:
Firstly the weight of 4 AA batteries sitting at my mouth level caused the front of the helmet to always hang down - rendering the friction locks at the headband useless - I ended up resorting to a short length of cord which runs from the top of the helmet to the back of the headband to stop that
The other issue I found was the attempt I made to have the power "switched", and removable - the 2 automotive crimps - frankly they proved more trouble than benefit. I'll cut them out and replace them with a soldered joint.


What else do I know about these units?
They don't like being dropped in quench buckets full of water
They don't like sweat dripping into them - day after stinking hot day
They can be replaced for around $30 via ebay (6shopriver is an example seller - no connection)

I don't consider the repairs I made to be a waste of time, they bought me some time so I could finish the job until I could replace the failing helmet. I will fully repair this helmet if possible and keep it as a back up.