Falls of Clyde 1878 by GAW - FINISHED - scale 1:96 - iron 40-frame hull center cross-section

[druxey]

Thanks for the explanation, Gerald. My local jeweller has a rolling machine to reduce precious metal strip in thickness, which is what I was thinking of. I suppose, from its rugged construction, that it could exert the kind of pressure you describe. I did understand your earlier explanation of the fabrication process for your 'bulb iron'.

[GAW]

July - 2016

 

Fig-29 - The Beam Making Tool (BMT) - this is actually two tools in one  The first I had much trouble with, attempting to copy the original method by making a cut in the end of the beam at the bend point, and then bending half to form the knee, leaving a triangular opening to be filled with a piece silver soldered in place.  As I stated last month, the brass would split every time. So I ended up with converting the cutter to a clamp, which then solved the problems.  The half of the BMT shown, consists of a pair of clamps.  The one on the right being fixed and holds the beam in place, while the one on the left pivots to an adjustable stop.  In operation the beam is first cut to length determined by it’s position in the Frame, then marked for the centre of the knees at each end.  The half round cut is made before setting the beam under the clamp on the left.  The lever on the right is then held firmly down to clamp the Knee section, before rotating the lever to a previously set stop.  The beam is then removed, turned around and replaced under the claps, so that the second knee can be bent to the same stop.  The stop is micro adjustable to accommodate any required angle for the knees. The second tool built into this unit we will see in operation at a later date.

 

Fig-30 - When the knee is bent the half round cut out becomes an almost straight line.  A touch with a file to true this up, and a scrap of flat brass silver soldered  at the corners, is all that is needed to complete the beam angles at each end.  These are then cleaned up with files and paper to remove evidence of the soldered joint and trimmed to the required length.  The parts are held in place with the bent wire ‘Dogs’ for the silver soldering process.

 

Fig-31 - Single Rivet Head Maker (SRHM)  - There are many places in the ship construction where single rivet heads are called for, or short rows of rivet heads, that cannot be accommodated with the  first RHM.  The beam end brackets being a case in point.  Here 6 rivet heads are called for at each end where the beam is attached to the reverse frame.  This machine, with double cam action, single pointed tool, and micro adjustment of the clamping table, provided for this need.  The bracket end is clamped to the table and passed under the the tool, which is then pressed down to form the rivet head, six being required as regular spaced intervals along the edge of each bracket.

 

Fig-32 - Showing the beam ends in the main hold of the Falls of Clyde, and the six rivet heads. Note also the detail of the rivets holding the frame to the reverse frame, and the the stringers.

 

[GAW]

For the moderator - had problems adding the photos this time, could not get them to upload in the right order, perhaps you can adjust them at your end please - Gerald

[druxey]

Brilliant - as usual! Love the tooling as well as the final product.

[GAW]

August

Fig-33 - With the ships beam formed of Bulb Iron, and the brackets cut - bent -and the opening filled with a plate, originally hammer welded, but in this case silver soldered in place, we are ready to complete the beam for fitting into the Hull Frame.  First the ends are trimmed to the correct length, then two brass angles - with rivet heads formed, are soft soldered to each side of the top edge, this being undertaken on the soldering table with the aid of the resistance (carbon rod) soldering unit.  A thin groove is cut into the soft soldering block and one tinned brass angle placed in it.  The tinned beam is placed on to this, with a second tinned brass angle placed on top of that.  Care is now needed to aline all three so that they meet at the top edge of the beam for the full length, at which point the carbon rod can be applied to heat the parts, melt the solder and fix the joints.

 

Fig-34 - Here we see the second tool, built into the ‘Beam Making Tool’ (BMT), used to form the curvature of the deck beam.  It consists of a double action cam operated press.  The working end consists of two thick plates, with a matching curved surface to form the camber of the deck where they meet. The lower one, next to the operating handle, being fitted with a hinge, and a groove across it’s face so that it can be turned up, to allow the finished beam to be placed into the groove.   When returned to it’s lower position, the handle is pulled, thus forcing the two plates together, and forming the camber to the deck beam.  All beams have the same curvature, they only difference is in their overall length

 

 

Fig-35 - We now return to the FMG, the top portion of which is the beam setting tool.  This consists of a hinged frame, to which are attached two adjustable fingers with cut outs to locate the two deck beams,  The distance between the tween deck and the main deck will be the same for the length of the hull, but the distance between the keel and the two decks will change as we pass along the length of the hull.  To accommodate this a micro adjustment has been provided to the platform holding the two fingers with the deck beam stops.  Each of the original aluminium frame plate patterns is so made, that the top of the plate represents  the position of the topgallant rail.  With the master frame pattern in place in the FMG, a small setting block  - so made to set the distance from the top to the main deck - is used to clip over the top of the pattern, so that the fingers can then be adjusted to their rightful position for the two deck beams.  The pattern plate is then slid out from the top of the jig, and replaced with the aluminium soldering table.  With the frame now fitted and held in place with wire dogs, the two beams are fitted in place up against the finger stops.. With the end brackets already tinned, it just needs a slight heat from the carbon rod to remelt the solder and secure both the beams in place.

 

Fig-36 - The first set of ships frames complete with deck beams and number tags, ready for the next set of fittings before being assembly to the keel.

[druxey]

Exquisite work, Gerald. Is the multi-arm soldering station your own creation or a commercially available unit?

[rwiederrich]

Oh My....words can not describe the feelings.......only to say that my father built a hull of a fletcher class destroyer once similar to this.....

 

I love the machines built to fabricate the hull frames.....

 

Rob

[mtaylor]

The tools and methods are just as much an art as what comes off them, Gerald.   Just stunning work.

[albert]

Fantastic, very very nice work.

[GAW]

September 2016 - Apologies for the slight delay in this one, it is the holiday season after all. Thank you folks, your generous comments are much appreciated - all of the tools are designed and custom made by me for the job in hand - a workshop is a never ending delight, when ‘almost’ all things are possible.

 

Fig-37  - So we now have a set of Ships Frames, well almost, there are still some fitting to be made and attached before we can start to assemble them, however I first needed to know what problems there could be in the process before advancing to that stage.  Apart from a model ship yard - jig - required to hold all the parts together, there appeared to be two further machines required before I could get to that stage.

 

Fig-38 - All of the Ships Frames run across the hull, for obvious reasons, but what holds these together are the Keels and Stringers, in the first place, after which the Ships Plating, which we will come to later.  The Keels and Stringers presented a particular problem.  The Frames are set at two feet intervals - scale size one quarter inch, indicating that rivet heads, now need to be placed very precisely  on the angles at these distances, further, that two rivet heads are needed at each frame crossing, as at each such point a small angle bracket was riveted to the Frame on the opposite side to the Reverse Frame.  So in the case of a Stringer made up of two Angles riveted together for their full length, where this crossed a Frame, it was riveted to it with four rivets, two to the Reverse Frame, and two to the small angle bracket.

 

Fig-39 - The placing of the Rivet heads on the brass angles to be used to make up the Keels and Stringers, now needed to be placed exactly 1/16” apart at 1/4” intervals.  I did consider a spiked wheel as with the previous rivet head maker, but the larger gap between the spikes would not allow it to work satisfactorily, so a new solution was required. This was to replace the single pin in the Single Rivet Head Maker (SRHM) with a double one with the two points formed exactly 1/16” apart. To place these at 1/4” intervals I devised a stepping mechanism that attached to the front of the SRHM, in place of the adjustable table. With the brass angle clamped to one end, this provided for twenty stops, equivalent to 40 feet of angle, which was about right for the lengths used.  For those interested in the mechanism, detailed photos can be found here < http://www.wworkshop.net/Falls_of_Clyde/Gallery-12.html >

 

Fig-40 - Before the Stringers and the Keels can be attached hundreds  of very small angle brass brackets, each provided with rivet heads on both angles are required, all cut to exactly the same length, and for convenience, cut from pre tinned material. Also required further down the line are the Ships Plates together with their Butt Straps, among other parts, again all needing to be cut to an exact length, and many times over.  For this I created a precision Guillotine with a hardened gauge plate cutter formed in two sections.  The main form of the blade provides for a long straight cut, but on the right side the blade is formed into a small ‘V’ for cutting the angled brass, with a ‘V’ed channel running up to this, so allowing the brass angle to be cut and not deformed in the process. The Guillotine is so made that it is provided with micro adjustment of several stops, that can go down to two feet and up to 40 feet, in scale size of course.  Note Jock the riveter, I made him early on as a guide to proportional size on all things, and found him very useful for the purpose. Construction details of the Guillotine can also be found on my web site.

[druxey]

Thank you for sharing the beautifully made precision jigs and tooling that you use, Gerald. They are impressive in themselves, and give lovely results.

[EdT]

I am sure the model will be extraordinary, but I continue to be most impressed - perhaps I should say knocked out - by the machinery you have created.  Simply astonishing - not only in its functionality but in its beauty as well..

 

Ed

[GAW]

October 2016

 

Fig-41 - Each position on a Frame where a longitudinal member - Keelson - Side Keelson - and Stringers etc. cross it, requires a small bracket riveted to the opposite side of the  Reverse Frame.  At the point that we are at now, the Floor will be between the two.  This allows the cross member that will be made up of a least two angle iron parts, to be riveted in four places each time is crosses a Frame.  Here we see one side of the soldering table, used to hold three of these angle brackets in place.  With the parts pre-tinned, and this side of the table being live - connected to the resistance soldering unit - one touch of the carbon rod at each section, is all that is needed to secure the joints.

 

Fig-42 - In April - Fig-18  - I made mentions of my use of licence in making a small slot in the top of the Floors to assist in locating the longitudinal member in the final assembly.  Here we see this locating slot extended across the small angle brackets, as also across the Reverse Frame.  The slot only extends down to half the depth of the angle, so that in the final assembly the part of the Keel or stringer engaged in the slot cannot be seen, but is sufficiently deep to locate the part.

 

Fig-43 - The longitudinal members on the inside of the hull of the Falls of Clyde consists of the Middle Line Single Plate Keelson, (Keelson for short) made up from a length of iron plate, with angle iron riveted to each side at the bottom and a further two lengths of angle iron riveted to each side at the top, and on top of this a length of flat plate riveted to the last two angle iron sections - the bottom two being riveted to the Frames, four riveted per Frame.

Out side of the Keelson, on each side are the Side Keelsons, made up from two lengths of angle iron riveted to a set of plates, called an ‘Intercostal’ - these extend down between the Frames, and are riveted to the frames on each side and the Plating at the bottom by way of short lengths of angle iron.

The next across the ‘Ceiling’, just to confuse you, this being the actual floor, are the Bilge Keelsons, again one on each side.  These consist of two lengths of angle iron riveted together with a length of Bulb iron between.

The photos shows these being assembled with soft solder on the soldering table.  The two slotted lengths being for the Side Keelsons, the individual plates forming the Intercostal. These slots engage with the ‘licensed’ slots in the Floors so that the Frame assembly goes together ‘egg box fashion’ which greatly facilitates the complete assembly of the hull structure.  In full size practice the ‘Intercostal’ plates would be assembled individually between each pair of Frames. The red markers is very significant and I will deal with them next month

 

Fig-44 - Another Tool and another Jig - The lowest row of Plating on the hull is called the Garboard Strake, which attaches the Frames to the Keel - this being a substantial length of thick iron, it’s purpose is to protect the ships Plating should it run aground. - It is the Keelson on the inside of the iron hull that is the backbone of the hull construction.  

Each of the plates for the Garboard Strake has to be bent, with each bend being very slightly less than the last, from the centre out to the stem and stern.  The Bending Tool, has micro adjustment to allow for this, although in the case of the forty centre frames for this model, the difference in angle was very slight indeed.  The bar and cage jig illustrated are for the assembly of the Garboard plates to the bar Keel.  The cage has a groove machined down the centre to accommodate the keel, the width of the cage being equal to the width of both plates, with the keel between. The second half of the jig consists of a length of aluminium with two flats set at the angle corresponding to that of the Frames at the centre of the hull.  This served for my forty frames, with a little adjustment for the extra angle at each end.  Had I intended to complete the Hull, then further jig plates would have been required to accommodate the differing angles as I proceeded fore and aft of the centre.  Although in practice, once the Garboard Strake for several plate lengths were in place on the bar Keel, and this attached to the first few Frames, it was less of a problem fitting the remainder.

In use the Garboard Strake plates are assembled on the aluminium bar, together with the bar Keel, with the aluminium cage over the assembly.  With all parts previously tinned with soft solder, and all of the parts lined up to their intended positions, it is a simple matter to heat and melt the joints together with the Carbon Rod tip in the gaps of the cage, which can then be moved along the jig as required.

 

[EdT]

I continue to be speechless over the tooling and methods - to say nothing of the scale.

 

Ed

[druxey]

Simply superb metalwork!

[GAW]

November 2016

 

Fig- 45 - Here we see the Garboard plates being soft soldered to the  Bar Keel, held firmly in an aluminium jig, that is it’s self clamped to the live soldering table.  The cage on the top can be slid along the plates, as the soldering progresses.  This is again the resistance soldering unit in action, that I feel is paramount in this sort of work, where a soldered joint is required, with out visible soldered - or nearly so, depending on your skill.

 

Fig- 46 - Now we come to the ships plating in general and the first thing of note is the ‘B’ in the centre, and the frames on either side.  This represents the centre of the riveted iron hull.  Note that the rivet heads are on each side of this opening between the frames, whereas fore and aft of this point, they are on the aft side forward of this point, and on the forward side aft of this point.  To understand the reason for this we need to go right forward and right aft to see what happens to the frames as they bring the plating to the stem and stern posts. In the centre of the hull the out side flat flange of the angle iron frame is at right angles to the frame.  As we move fore and aft of the centre line, an ever increasing angle has to be formed on this flange, relative to the frame across the hull.  As we move forward for example this angle becomes very acute, such that if the flange was forward of the frame it would be impossible to attache the rivets to it as the angle becomes less with each frame.  By having the flange aft of the frame , the angle increases, so allowing more room for the riveters to do their work. And the same for the rear frames of the hull, with the flat forward of the frame, the riveter has the maximum space in which to work.

This would appear to not make a great deal of difference with regard to building the model, as the rivet line - flange of the angle iron - are still placed two feet apart.  However in making the Floors, I did leave a small pip at the bottom of each, to assist in locating the frames to the Bar Keel.  This means that at this centre point all frames forward are reversed, thus requiring the Floors to be on the opposite side of the frame, so the locating holes for the Floors, needed to be plus one angle iron width further apart at the centre.  This is why there is a red mark on the bar keel, each side of which these two holes are located, showing the centre of the model hull. 

 

Fig- 47 - The Bar Keel is now assembled with the Garboard Strake of plating on each side and awaiting the Butt Straps to be riveted/soldered across the joints where the plates butt against each other.  One big mistake is visible here, and was something that had to be watched for at every stage of the construction and that is, that the Bar Keel has ended at the same place as the Garboard Strake plating.  This is a fatal error as all joins in plating, stringers keel parts, should be at least five frames from the next, as it weakens the structure. In this case it should have been places in the centre of the Garboard Strake and not at the end.  This was amended later, but it was a problem having decided to start construction at the centre of the hull.  If I were to remake this model, it would be started at one end and work through to the other, but this is a learning curve, and I was still at the bottom of it.

 

Fig- 48 - The RHM is now being used to provide the rivet heads on the ships plating, together with strips, later cut to length for the Butt Straps. With the adjustments built into the tool it is possible to run any number of rows of rivet heads as required, and with a little practice to have them all start at the same point.  Although looking at the riveting on the inside of the hull on the actual ‘Falls of Clyde’, they ware not so accurately placed as one might imagine.  The rivet heads are only visible on the inside of the hull as the heads were counter sunk on the out side, to give a smooth flow to the water around the hull, an important consideration when all you have is the wind as your motive power. 

[GAW]

December 2016

 

Fig- 49 - Please bare in mind that there is a big BIG learning curve for me in this build - a first time for me, and as no one that I know of has written anything on the subject of building an iron ship in miniature, it is called flying-by-the-seat-of-your-pants, so many mistakes on the way, most of which will be shown as is.  Here we see the first stage in making up the ships plating - Sets of six plates, complete with rivet heads and Butt Straps, ready to be assembled/attached/soft soldered to the Garboard Strake. The mistake is that although the first couple of strikes of plating will be in a straight line, there after, there will be a very slight curve in them.  At the  4th -&- 5th  strakes it is very slight indeed, but if ignored, can give big problems later on.  It is still possible to make up the plating in lengths of several plate such as this, but we will see later, a very simple way to finely adjust that all important curve in laying up the plates.  Note the small strap across the Bar Keel between the first strake of Plating on each side, at the point of contact for each Frame.  The Frame must be in contact with the ships Plating at all points to be able to be riveted to it.  As the Plating is in the form of One in and One out, a filler piece is required between the ‘Out Plate’ and the Frame at each point of contact.

 

Fig- 50 - The ‘Ship Yard’ - the last of the tools.  This consist of a precision  machined aluminium plate with grooves to hold columns on which are mounted a series of arms to hold the frames in place and vertical while they are assembled to form the ships hull.  Six columns are provided each of the columns has two arms, with three fingers at the end of each.  These correspond to the spacing of the Frames.  All of the parts are fully adjustable at all points, so could accomodate the Falls of Clyde hull for it’s full length.  Although the plate will only hold 24 Frames at one time, the Hull, as we will see, can be moved through the ‘Yard’ as the build progresses.  The centre of the plate has a groove down the full length that contains a carriage, to which the Bar Keel and Garboard Strake assembly is held in place with a clamp. 

Over this is a mechanism/clamp, also fully adjustable,  to hold the individual frame in place while it is soft soldered to the assembly below, the top of the Frame being supported  at two points on each side, by the fingered arms on the columns as can be seen,  The columns and the frame clamp can be relocated to any position on the base plate to suit the job in hand. Provision is also made to make the whole assembly live, when connected to the resistant soldering unit, the essential means by which all of the soft soldering is undertaken on the hull assembly

 

Fig- 51 - The Frame Clamp set up with a Frame under the business end, while the sides of the frame is held perfectly vertical by the fingered arms attached to the columns on each side.  Note the PIP at the bottom of the Floor in the centre, which is set over a corresponding hole in the Bar Keel made to take it, and so locate the frame in its correct position.  The next step is to flux the area to be soldered, slip in between the Frame and the Keel assembly a small sliver of flattened soft solder, adjust the clamp to press the parts together, and apply heat to the precise area with the live carbon tip to fuse the parts together.

 

Fig- 52 - Here we see the first series of frames being assembled to the keel, with the next Frame ready to Go-Up.  The fingers on the column will then be slid in and be locked in place, once the frame is lined up with it’s neighbours, a solder tab slid in place at the bottom, clamp applied, heat applied, assembly moved forward and process then repeated until all the required Frames are in place.  Note that it is only alternate Frames that have deck beams, and that each is provided with a tag holding it’s number.  With twenty Frames made and ready for assembly at the centre section of the hull, all seemingly of the same shape and size - which they are not -  big problems are there for the unweary.  Note also the seeming disk at the bottom of the photos.  This is in fact a reel of soft solder that has been passed through the flat rollers of the RHM to make it paper thin, then trimmed to three fingers.  These are snipped off as required and used to sit between fluxed and tinned parts to be soft soldered together. Apart from the use of tinning parts - applying a thin layer of soft solder  to the part -  the soldering iron is not used at all in the assembly of the hull.  The reason being that it will of necessity leave a solder residue after it’s use.  Here the soft solder is used in place of the actual rivets, so none should be visible in/on the finished joint.  The only way - that I have found - is to use a minimum amount on each surface - tinning - and place a very small - tab/sliver - of solder between the parts.  Then hold the parts together and apply heat - in this case with the tip of the resistance soldering carbon rod.

[GAW]

Seems the photos have come over in the wrong order again - they arrive correct for the preview, then get mixed - if some one could adjust the order at your end,  I would be most grateful.

[druxey]

From your clear descriptions the sequence is obvious anyway, Gerald. The number of jigs you make and use is quite extraordinary. Brilliant!

[Ian B]

The work involved in prep and creating jigs just to make a section is outstanding--- watching this build with amazement--- thanks for taking the time to share it in such detail.

 

Cheers Ian

[mtaylor]

Gerald,

 

I'm enthralled with this build. 

 

As for the picture problem.. I think you're missing a step or two.  Have a look here: http://modelshipworld.com/index.php/topic/540-how-to-add-pictures-in-your-posts-and-pms/

[rwiederrich]

Amazing........mixed up pix an-all...simply amazing.

 

Rob

[EdT]

GAW, my amazement and speechless state continue with each new post.  

 

If I may make a suggestion on the pictures.  I think there is value to interspersing them in the text, especially when they are lengthy descriptions/explanations describing each.  After loading the pictures in the "More Reply Options" frame, place the cursor in the text where you wish to add a picture, then click on "Add to Post" in the box at the lower left.  This will place that picture at the cursor location.  Repeat for the others then check the placement in the Preview screen.

 

Hope this helps.

 

Ed

[Mike Y]

That looks like a true mini-shipyard. The only thing left is to add a tiny welding robots to connect the metal parts together!

[Mirabell61]

awesome metal work and fixtures Gerald,

 

will those tools be multipurpose for other ships frame making as well ?

 

Nils

[GAW]

January 2017, A Happy, Healthy and Productive new year to you all, and thank you for the comments and advice, we never (should) stop learning - and no Mike Y, no place for Welding Robots in a ship yard of 1878 that is why you will find Jock the riveter, turning up from time to time here, as in Fig 40. 

 

Yes Mirabell61, the tools are basic, ie, made to do a job, if the project is a riveted iron or steel ship, then these tool could be used to make it. I should point out here, that the tools were all made before the model was even started - I brain stormed for 9 weeks, to imagine my self through the project, building the tools as I went.  Now at this end of the completed project, I and perhaps your good selves, can see more simple ways of doing these things.  But the other side of that, is that I am finding some of the tools very useful in other modelling field as well.

[GAW]

 

Fig- 53 - Using the resistance carbon rod tip to heat the parts to melt the sliver of soft solder between the frame and the garboard strake of plating that can be seen going together in the Fig-52.

[GAW]

Fig- 54 - These are the parts shown in Fig-43 being assembled on the soldering table,  shown here, bottom right,  ready to be assembled into the centre 20 frames.  They consist of the Keelson - properly called a ‘Middle Line Single Plate Keelson’, made up of a centre plate, with two angles riveted at the top and two at the bottom, and a second plate riveted on the top called a Rider plate.  Next out on each side are the Intercoastal Side Keelsons, one on each side, consisting of a series of plates joined together at the top with an angle on each side.  Then follows further out, the Bilge Keelson, comprising of a length of Bulb iron, with an angle riveted to each side.  The final longitudinal item is the Bilge Stringer, that consists of just two lengths pf angle irons riveted together, at which point we are now starting up the side of the inside of the hull. All of these are directly riveted to the frames where they cross. NOTE substitute soft solder where you see riveted, one is real life the other ‘in miniature’.

 

 

The Intercoastal Keelson, in fact consists of a series of plates set between the frames at this point,  each of the plates is riveted to the Frame fore and aft  with a small angle bracket, and also to the ships Plating below.  The tops are joined together longitudinally with a length of angle iron on each side, all riveted together.  This is where I have used licence, and not followed standard practice, adjusting the parts to meet my needs.  These being to make the plates as a single length, but slotted, to fit slots in the frames, so as to assemble them egg box fashion.  With the slots precision cut, it allowed the frames to be placed at the bottom level exactly were needed and squared off to the Keel. I did not fit each plate with brackets to the frames fore and aft - (1) because it was almost impossible to get to them with a heating device to solder them in place at each station, and (2) they could not be seen in the model when finished if I had included that detail.

[GAW]

 

Fig- 55 Here we see a pair of clamps machined from an aluminium ‘U’; section, the slots corresponding with the spacing of the frames. It is made in two parts, the outside being the ‘U; section, while the inside is a flat aluminium plate.  After machining the slots and assembling the inner plate, secured with four knurled screws, it was bent on two planes, to match the assembled middle Frame Master Patterns, to copy the slight curve of the deck and also the very slight curve of the out side of the hull in the centre section.  The adjustable uprights on the Ship Yard can locate and accomodate 9 Frames, OK for assembling them on the Keel, and allowing the Hull to pass through the Ship Yard, but not good enough to locate sufficient Frames for assembling the longitudinal members in their rightful places with precision .  These Comb Clamps, as I call them, will hold 21 Frames at the tween deck level, in exactly the correct place for fitting all of the Stringer Plates and most of the ships plating.

[GAW]

Fig- 56 With all the parts ready tinned and slotted in place, it was just a matter to run the heat along each side to fix/melt the solder and fix them in place.  Here I have modified a copper soldering iron bit to give me a short length of hot iron. However I did find that it took forever to heat up enough to do the job, and finally resorted to filing up to the same shape, to the end of a carbon rod and using that.  In use, one needed to make contact with the parts with the tip of the rod, then with the foot switch, switch on a low power, and just slide the heating carbon tip along the top of the pre- tinned angle, then switch off and remove the carbon tip. My concern in not using the carbon rod at this stage, was the shorting of the rod against the other metal parts deep down in the hull should I inadvertently touch them - easy done.  Shorting is the only danger with the use of the resistance soldering unit, if the live rod does touch another part, one will get ‘spark erosion’ ie a hole in that part.  However some further experiments, showed that all I needed was a thin tube of paper - any paper - around the rod with just the tip showing to solve the problem, as will be seen later in the project. The heating at the tip is not on long enough to set the paper on fire, but even if it did, it would course less damage than ‘spark erosion’.

 

 As I remarked earlier, this is flying my the seat of your pants, you learn as you go along, hopefully doing as little damage as possible in the process. Note that the end of the Comb Clamps can be seen at the top on the assembly on each side at the tween deck level.