August 28^th

I’ve had a bit of a hiatus for one reason or another but I’m back with some things big and some things small.

The main boom has now been fitted with all of its ladders and platforms for the maintenance staff. 

Figure 101 shows a service platform for the static line attachment from minor boom top to main boom midpoint. Of course when the main boom is up at a fixed angle of 38 degrees this platform will be horizontal. It will be noticed that the ladder to this station from the main stairway below is protected by a closed safety cage. Of course it will be vertical in the final stage. 

Figure 102 shows a pair of vertical ladders up to the service platform across the bridge. Also visible in this picture are four 4inch diameter aluminium guide pulleys which have been mounted to run at the ends of some tubular struts, continuing the boom’s overall tubular construction. Some special wraparound straps were fabricated to join these struts to the bridge. All the attachments of stairways and ladders are done in the same way. The total stairs/platforms job has used an enormous quantity of narrow strip.I found my initial estimate was far out and had an extra 300 minted. They have all been used to the very last one.

Fig. 101: Service platform for static lines on main boom

 

Fig. 102: Service platform across bridge, with 2 ladders

Figure 103 shows the controller’s binnacle, with a close up of his/her cabin in figure 104. The cabin is seen fitted with chair, drag and hoist levers, a small shelf for coffee pot etc. and a modern day thing is a screen to monitor machine efficiency. 

The cabin is enclosed by 3mm glass panes. At the scale of 17 to 1 these would be 51mm on the prototype, probably about right for its armourplate glass.

Fig. 103: Controller's binnacle

Fig. 104: Detail of above

 

In Figure 105 some measures against cable derailment are shown. 

These have also been fabricated from aluminium tube, to continue a theme. Judging by the paint scratches on the prototype devices, there were times when the mighty 5 inch diameter steel cables flicked upwards by about two feet.

Fig. 105: Cable derailment prevention device

I have now acquired some 70mm aluminium stock to machine some cups to hold the ends of a 1300mm long and 50mm diameter tube connecting the tops of the two minor booms. 

The turned devices can be seen in figure 106.

Fig. 106: Aluminium cups to hold ends of connector tube for two parts of minor boom system

If the things described so far are all small and/or cosmetic then the two heavy duty winches which have been mounted on the fronts of the forward struts of the gantry are the opposite.

At this stage the left hand minor boom has been attached too and is seen in the horizontal position in figure 107.

In figure 108 it has been lifted part way up. In figure 109 it has been lifted to its final angle, while figure 110 shows the right hand minor boom also attached.

The small motor car trickle charger seen at bottom right in figure 109  is strong enough to power only one winch at a time. 

When more motors are turned on I use the transformer rectifier made for me by Postma and Postma of Port Elizabeth. It can put out 83 amps at 12 volts.

 

Fig. 107: Left hand minor boom in horizontal position

Fig. 108: Ditto, part way up

 

 

 

Fig. 109: Ditto, final angle

Fig. 110: Right hand minor boom now attached

 

June 17^th  2021 

I have had to take a break from Big Muskie in order to do quite an extensive carpentry job but now I’m back at my core business. The first thing to do was to complete the two minor booms ( one from scratch) with all their equipment auxiliary to the main structure which is tubular aluminium, similar to the main boom. Figure 95 is an overall view of the two 9 foot booms side by side. Figure 96 shows the top ends of the two units. Each is fitted with four 4 inch turned aluminium V pulleys which are part of the mechanism for pulling the 18 foot main boom up into position.These pulleys run on an 8mm rod which is journalled into a very strong box built from 2mm plate and which is fixed to the aluminium tubes of the structure. Also visible in figure 96 are the staff access stairs and working platforms.

 

Fig. 95: Overall view of two minor booms

Fig. 96: Closer view of the upper ends

Figure 97 is a close up view of the boxes alluded to above. It will be seen that there are two other devices which run on each of the 8mm axles. Each of these is a heavy gauge plate with 6 dice like fittings bolted to it. The latter are the anchoring devices for the static lines which will hold the main boom in position. Each is a 20mm length of 16mm square mild steel stock with holes drilled at right angles. One hole is 6mm and has an M6 bolt passing through it to anchor it to the heavy gauge plate while the 5mm hole will have an M5 static line passing through it. Figure 98 is a close up of the remainder of the 60 dice like fittings for the 30 static lines.

 

Fig. 97: Pulley clusters and static lines anchor blocks

Fig. 98: Some anchor blocks

The static line system consists of 12 which connect the top of the gantry to the tops of the minor booms, another 12 which continue these up to the top of the main boom, 4 more which connect minor boom tops to the centre of the main boom and finally 2 which will form a cross brace to prevent the minor boom collapsing sideways. The latter eventuality is remote as the anchor at bottom ends is via 2mm plates journalled onto M12 rods and 4.5 inches apart while the connection at the top end is by a length of 50mm thin walled aluminium tube which captures the look of the prototype well. (See figure 99.). I am waiting for some 70mm solid aluminium solid to machine two cups to anchor the ends of this piece of tube. All of this should give immense resistance to sideways moment.

 

Fig. 99: Length of 50mm diameter aluminium tube (cat for scale!)

Finally in figure 100 are shown the two winding drums each driven by two 12V motors which will provide the pull on the cables to pull the main boom up into place. Previously these winches were employed on the wooden wheeled crane used to handle the two heavy toroidal units which formed the basis of the swing facility.

Fig. 100: Two winding drums

 

 

3/18/2021

 

A significant milestone was passed recently. The walking feet were fitted and lift and slide tested. The lifting units performed fine and confidently lifted the machine onto the four pseudohydraulic lift units. However at the first attempt the tub was being left about 3mm behind. The cause of this was the tub itself flexing by that amount when its 140 kg weight was suspended by the central support rod. When adjusting the pretensioning of the tub at an earlier stage I had tried to estimate what the tub would do by stepping onto the floor of the mainframe. My 85kg weight could not cause movement at all. This was not a good indicator of the way the tub would behave since the latter is only 11 holes deep while the mainframe( which is all I was testing) is 22 holes deep. The cure was simple and just required me to climb partially inside the hall, undo the locknut on the rod keeping the two units together and then tighten the nut 4mm and relock it. This effectively pretensioned the tub some more so that on retrying lift the tub followed the rest of the machine up off the ground. On lowering the machine I retested swing to see that I had not jammed it but it was fine. The eight swing units are tremendously powerful and easily handle the effective extra weight of about 180 kg. Figures 87 and 88 show the overall view of the machine from two slightly different elevated positions. The full width of the machine has been reached now, 9 foot. Figure 89 shows me inside the machine adjusting the tension on the bolt.

 

Fig. 87: Elevated front view showing walking feet installed

Fig. 88: Dittom moved slightly to one side

Fig. 89: Me inside adjusting tension!

Initially I had been worried that there would be some rock to the machine when it went up on its four lifter “stilts” but there was none at all. The action of lifting is slow, taking about eight minutes from fully retracted to fully extended for the feet, but the motors remained cool during this time and so did not seemed overstressed. The booms, bucket and ballast will add about 300 kg to weight but I do not expect problems because of the above observation.

Figure 90 shows the two walking feet on the left side, and figure 91 is a closer view. In these pictures the 20mm horizontal stainless steel rods on which the machine slides are clearly visible. Also visible is the upright brass fitting with an M20 thread into which the rotating M20 rod drives up and down driven by two 12V motors geared down to give huge torque. As usual I bolt pinions to gears to avoid torque going through grub screws on axles. They would just rip loose. The large vertical brass unit has a transverse 20 mm hole milled so that it can rock slightly in the slide piece. This is to allow the feet to be planted on slightly uneven ground. I had thought this might be a source of machine rock but the rigidity with which the lifter units are bolted to the machine is preventing this from happening. The slide piece itself is a box made of 2mm material with a pair of   brass rods bored out to a fraction more than 20mm. In fact the whole of the central section of the walking foot is made from 2mm plate except for the bottom which is made of 1mm plate, which is fine since the weight is spread out over a large area.

 

Fig. 90: Two walking feet on left

Fig. 91: Ditto, but a clearer view

To accommodate uneven ground the front and back feet on either side are hinged in the centre. Figure 92 shows this hinge, a 10mm rod with an aluminium machined disc to imitate the look of the prototype.

 

Fig. 92: Central hinge between walking feet

The walking feet will be finished off by installing a boxlike hydraulic pump housing on each. All four are shown in figure 93. The units are plated with recycled coffee tins which were easy to bend into small radius curved corners to continue the theme of such corners started on the hall. The small box at the rear of each I believe contains air filtration equipment so that filtered cooling air is made available to the powerful hydraulic pumps. The air intakes point downwards to prevent rain from being taken in. There is also a door opening on each, opening out onto a walkway which will allow staff to enter from the top of the foot which in turn is accessed from the ground by ladder. Although I am not modelling the inside of the pump stations they would also hold tanks for hydraulic fluid. There was a total of 200 000 litres of fluid on the machine for all the hydraulics. That would fill 4 normal sized domestic swimming pools!

 

Fig. 93: Four hydraulic pump houses

Before I close up the hall I am going to install 10 ersatz swing motors shown in figure 94. The employ recycled paint cans and coffee tins. I think the small device at the top is some kind of electrical unit in reality. Maybe a capacitor?

Fig. 94: Ten ersatz swing motors

 

 25^th February 2021

 Further work on the machinery hall enclosure has now been done, almost bringing this phase to completion. The hall has now reached it full width of slightly more than 7 feet.

 

Fig. 78: Left frontal view (whole machine)

The side extension “lugs” on either side have been enclosed, as can be seen in figure 78, a view from the left front. A pair of stairways connect the left front roof to rooftop walkways which each cross over to the other side of the machine. The long stairway to the left gantry top leads off one side of the front walkway while a similar stairway to the right gantry top leads off the other side. At first I wondered why staff couldn’t just walk across the roof but then I pictured a wet or ice covered roof and I saw the reason! The purpose of the rear walkway seems to be to allow entry to the air filtration plant from either side and would also allow staff to clean insect build up from the front insect mesh using brushes on long poles.(My guess anyway.)

 

Fig. 79: Closer view of left front, showing removable side panels and stairways to the roof

Figure 79 is a closer view of the left hand side and shows the two short stairways in more detail. Also visible is some side panelling, in particular two removable panels measuring 18 by 15 inches. The space between them will be filled in by fixed plates when I am finished installing the rest of the machinery hall equipment. Still to come in this regard are the high powered hydraulic pumps which lift the whole machine on its walking feet and ersatz swing motors.

Fig. 80: Rear view of right hand hall extension. Note removable panels again
 

Figure 80 is a view of the right hand extension from the rear. The hole seen here will be filled by a door on hinges. I have seen pictures of Big Muskie with the door open and a cantilevered hoist beam extended outwards. I presume this is used to service the hydraulic pumps and other equipment out of reach of the main service crane. Also visible in figure 80 are two more removable panels. Note the asymmetry between left and right hand sides. As mentioned before this is because of the large cooling air plenum installed in the right side.

Fig. 81: View from rear showing air filtration plant in top floor

 

Figure 81 is a view from the rear showing the still open filtration plant. There are four large impellor compressors and each is mated to a boxcar sized microfilter unit. The two units on the right supply cooling air to the winding drum area and the two on the left likewise to the motor generator park which is visible below on the main hall floor. The main 5 foot service crane is visible between the two floors. A second, smaller crane rides on rails which traverse the filtration room. A small red plastic Meccano motor which powers the small crane can just be made out at the top of the picture. The crane has a cross traveller but it is not powered and neither is hoist due to space constraints and I have been unable to source small enough motors. The main crane has four wheels powered by a large 12V motor situated on the left side. Drive is taken across to the right by an 8mm shaft. A 4mm shaft would suffer from too much twist over such a long distance and the motion would be jerky as a result. The cross traveller on the large crane is powered by a small Meccano motor as is hoist.

 

Fig. 82: Front insect screen on air filtration plant

Figure 82 shows the insect screen painted black and sloped backwards at the front of the filtration plant. A similar screen will be installed at the rear.

 

Fig. 83: Later picture of rear with roof complete and four of six rear doors installed

By the time figure 83 was taken the last piece of roofing had been completed and the rear wall was well advanced with four of the six doors installed. Figure 84 shows these doors in the open position so as to allow the service crane to exit along with its load. Figure 85 shows a boxcar sized microfilter unit with staff safety rails around top.

 

Fig. 84: Rear doors opened

Fig. 85: A microfilter unit

Fig. 86: Main service crane rolled out the back on cantilever rails

 

Figure 86 shows the main service crane rolled out the opened rear doors on the cantilevered rail extensions. The two central wheels on either side are driven.

 

15^th Jan 2021

 

The machinery hall enclosure has now been considerably advanced. All twelve of the main vertical stanchions and roof they support via six trusses have been installed (except for a short section of roof at the very rear). The twelve matching support stanchions the service crane rails are also in place and the rails themselves are nearly complete. Figure 70 shows a current overall view from the offside front. It shows a number of things apart from the front part of the roof. The second floor which houses the air filtration plant can be seen to the rear of the roof over the winding drum area. This view seems to show a translucent front to the area as the light from the garage window behind is visible through it. This is correct as this feature is meant to represent a fine mesh screen which prevented insects and birds from being drawn in by the air intakes on the prototype. I originally intended creating this screen out of  a fine galvanized fly screening but dropped the idea on learning that this product is  only available in nylon now at my hardware store. Instead I created the sense of permeability by reaming the 4.2mm holes in a series of 5 by 11 hole plates out to 8mm (all 55 except four in the corners). I know that this would not be effective against insects or even small birds if scaled up by a factor of 17, but  then like all Meccano it is only a representation of reality.

Fig. 70: Elevated frontal view

 

 

 

Figure 71 is a view into the air filtration plant room from the rear, which is still open. The floor is supported by three trusses, the front one being a combination roof and floor truss to allow development of the curved roof into a flat floor. The rear truss is similar allowing the reverse transition while the central one is just a floor truss. Pictures of all these have been shown earlier. The insect screen is visible to the front and there will be a similar screen at the rear. Both screens have a slant to them which would prevent rain from being drawn in. At the far end of the picture an impellor type compressor can be seen. There will be four of these, each being mated to a large microfilter stack. I have no information on what these units looked like on the prototype but I did find the website of a company which specialises in building similar units for modern day draglines so I’ve had to extrapolate a bit!

Fig. 71: Inside the air filtration plant

  

At the top of the insect screen a strong roof support beam can be seen spanning the six foot wide from wall to wall distance. Attached to bottom of this beam is a five foot long rail on which a small service crane (about 22 inches wide) will run. The rail on the other side can just be seen in the top right of the figure.

Fig. 72: Close up of an impellor compressor (with ersatz motor in black)

 

Figure 72 is a close up of an impellor compressor unit with ersatz motor using a paint ca in black. The two compressors on the right supply cooling air to the front of the machine and they do this through a duct or plenum which is visible in figure 73 which shows the underfloor area of the filtration room. The silver plenum is created entirely out of recycled coffee tins as are the compressor/microfilters except for some laser cut quadrant plates seen in figure 72.

Fig:. 73:  Underside of filtration plant showing silver air supply plenum.

Fig. 74: Top of gantry, built from 2mm plate

 

Figure 74 shows the top section of the right of the gantry completed. It employs 2mm gauge plate as it has to support the forward pull of the boom system and the bucket (total weight about 200kg).

Fig. 75: Left hand gantry top showing aluminium pulleys of boom hoist mechanism

 

In figure 75 four 4inch diameter aluminium pulleys can be seen at the top of the left hand side of the gantry. These form part of the boom hoist mechanism. There will be similar pulleys at the top of the left hand minor boom and the whole device will be repeated on the right side.

Fig. 76:  Stairs to the top of gantry going up right front gantry stanchion.

 

Figure 76 shows a stairway from the roof up to the gantry top going up the right front gantry strut. There is a similar stairway on the left and the two are connected by a walkway going across the roof. The path to the roof will be from the top of the left lug addition to the hall which can be seen in figure 70. the walling of the two lugs will feature two large removable panels on either side, to see inside the finished hall.

Fig. Fig. 77:

Hall walling has now progressed to the rear. Figure 77 shows the right rear corner with the curved plate profile in red continuing that of the heavily built under frame in green. Also visible is the cantilevered extension to the service crane rail which will allow said crane to move out the back of the machine to drop its load on the ground (or the reverse). There will be a rather complicated set of six doors in the rear wall which will allow the crane plus whatever it is carrying to do this. Two doors open outward and four open inward. This is necessitated because of the double crank design of the back of the machine. Finally the two small holes seen in the walling are for the extractor fans from scrapped computers.