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Fire Monitors Part 1

The white metal items supplied are OK but really don‘t lend themselves to being working items. Graham93 has already completed a version which looks just like the drawing and photos available, and are the best I’ve seen. The bar has been set so here goes, whenever an item like this is been contemplated it’s always good to spend some time in planning a sequence of operations and assessing the problem area’s at the start of the work and if possible dealing with these parts first. Failure of the difficult process doesn’t mean you have wasted work on other parts that are now scrap. I think the most difficult and problematic piece is the pipework that sits at the top and curves round in two halves, this in reality is a casting, however replicating it can be done using brass pipe. Brass pipe can be purchased in annealed form; however my stock wasn’t so the first job was to anneal the tube. Heating to a dull red heat and allowed to cool, this treatment will soften the metal completely. In some books it is suggested that the brass should be quenched in water (which is what I do) after heating but this is to speed up the commercial process, and quenching has no effect on the annealing process. So tube annealed we need some method of retaining its tubular form during bending, in plumbing I use a spring but when you compare wall thickness/dia a spring would have to be mighty strong and so small. An easy alternative is to crimp one end of the tube and put some soldering flux down the tube, follow this by heating with a low temperature blow torch to melt solder and fill the tube, then allow to cool. You now have a soft tube which when bent will hold its shape. That’s the next challenge, the shape, and being able to replicate it twice, so an easy jig is required. Having marked out a scrap piece of hardwood I cut the “U” shape using the band saw and filled a groove along the top edge, this was then placed under my drill press with the appropriate dia bar (this must be calculated accurately as it helps to create the final form) on top of the tube, then just pull gently down (it takes very little force) this jig leave a small amount to finish bend to a complete a circle, the excess length is trimmed off and then I used a piece of hard wood with a small radius on the end to tap the final curve. Next the circle needs to be cut into two pieces I used a small slitting saw in the . Now it’s time to remove the solder, simply heat up holding in plyers and then shake vigorously to expel the solder. (Make sure you do this on your own and wear safety glasses.) The white metal “main pillar fitting” and the monitors final “exit pipe” will be used in the unit and all that is required is to mount them in the lathe and drill a 4mm hole through each and clean up the casting. Next I cut 4 pieces of 4mm brass pipe; these will form the main water passage. Two more machine turned items are the “pivot post top” that feeds water through the 2 brass pipes into the “junction block” which then feeds into the exit pipe, sounds all very simple? Having made all the components, it’s time to think about fastening them all together. First items to be joined are the “upstand pipe” to the “pivot post top” X 2 also the “feed to exit pipe” and the “junction block” X 2, these four joints are all to be silver soldered. I mounted them in a piece of wood and placed a tight spring brass ring around the upright pipe to stop then sliding down when heated. Having the joints spotlessly clean is paramount, the flux is added, I insert very small pieces of silver solder into the holes at the top cross holes (less is more) a gentle heat, and watch as the flux goes “glassy”, this is closely followed by the solder melting, watching at the lowest point of the joint for the tell-tale shinny liquid metal. No fettling is required so the 4 parts are dipped for 45 minutes in masonry brick cleaner (dilute hydrochloric acid) the parts are now clean and ready for the next soldering activity. See part 2

5 years ago by mturpin013

Forum

Workshop

"Nifty little lathe,- Proxxon- looks German? " Correct! (Richtig😉) https://www.proxxon.com/en/micromot/24150.php The little is also Proxxon. https://www.proxxon.com/en/micromot/27110.php There's also now a CNC ready version - There wasn't back then 😭😭 https://www.proxxon.com/en/micromot/27112.php Might invest in the MICRO compound table KT-70/CNC-ready! to upgrade my manual job! They have a range of bigger versions as well https://www.proxxon.com/en/micromot/precision-lathe-and-milling-systems.php Not the cheapest around, but built like the proverbial brick "whatsit" house😉 Google / Ebay around, should be able to find some at reasonable prices. Think I paid around €150 for my little lathe back then. The miller around €90. Happy machining folks, don't forget the goggles🤓 Cheers, Doug 😎 PS Odd!? Someone else's pics keep creeping in?? A new phenomenon!😐

5 years ago by RNinMunich

Forum

Workshop

My granddad's pal/neighbour had an engineering workshop in his Glasgow tenement flat (ground floor)from 1945 until he passed away in the mid 70s he used to do sub contract work for D&W Hendersons shipyard don't know what the Corperation thought as it was a council house .I remember there being a big Colchester lathe and a and a pot arc welder,thought I should mention he was single and the house smelt of coolant my grampa used to do a lot of welding for him.

5 years ago by marky

Forum

CNC boat kits...?

My plan is to trace PDF files into DSM and output as DXF, or work up my own drawings. I have DXF to G code so I guess I could deal with your files. When finished, my OX will be used for all sorts, cutting aluminium is a must, Daughter has demanded name plaques for her horses stable, she reckons her horsey pals will pay for nice carved name plaques so who am I to argue! ply and balsa cutting will be essential and possibly light brass sheet, hence my first choice of the 900 Watt DeWalt router. I may well end up with an arsenal of spindles/routers and eventually a laser head. I am using the CNC shield for now but the intention is to use a Rumba board, a versatile Arduino mega 2560 based board with loads of output options more commonly used on 3D printers, I have upgraded 2 of my printers with them already. Like 3D printers, the options for modifying/tweaking are endless. I will be fitting endstops, but I may use TMC 2130 drivers, which do not need endstops, as soon as they detect a substancial increase in current they switch off. My Mk3 Prusa has them, certainly reduces the ammount of wiring! I have a notion to draw up some plans for a series of warship boats at rc able size, ie, 47ft Whaler, Skimming Dish FML Cheverton Launch etc, interesting boats but rarely seen actually on the water as working models. I have a so a plentiful supply of milling cutters is available for a range of jobs.

5 years ago by Nickthesteam

Blog

Detailing the cabin – Part 2. The Roof Rails.

Some hardwood dowel is supplied in the Vintage Model Works kit for the handrails that would look perfectly acceptable for most builders but as I’m going a bit overboard with the detailing of my boat I chose to fabricate mine differently to look a little more authentic. This involved selecting some obeche stripwood of suitable dimensions and carefully measuring and marking out the positions of the supporting legs and the spacing between them. Again I used some ‘photos of the NMM model as a guide for this. Fortunately I had previously treated myself to a vertical stand accessory for my Dremmel drill and I used this as a with the addition of a suitably sized sanding drum and an improvised ‘fence’ attached to the base of the stand. After making a test piece I also chose to attach a vacuum cleaner hose to the stand to extract the dust as the process generates quite a lot! Milling out the recesses in the obeche strip was a remarkably quick process but the subsequent hand finishing using abrasive paper glued around a dowel and some abrasive pads took a great deal longer to achieve the final profiles. I was very pleased with the final result and so I applied several coats of Teak stain before hand drilling a 2mm hole in each of the supporting legs to take a plasticard rod which was superglued in place. These form fixing spigots that will enable me to easily fix the rails through the roof without using epoxy or superglue on the roof surface but on the underside of the roof instead. The legs at each end of the handrails were drilled to take 1mm rods as the legs are a bit smaller. The rails were then laid out on the cabin roof and with the aid of some masking tape the position of each plasticard rod was marked and then the drilling centres marked with an indent through the tape onto the roof. The fixing holes were all hand drilled through the roof and the handrails pushed into place before being secured with a drop of superglue on the underside. When set the excess plastic rod was cut flush with the roof panel. The finished result is very pleasing 😀 as seen in the last pic along with a sneak preview of the searchlight.

5 years ago by robbob