Friday, March 17, 2017

TUTORIAL - CUTTING PVC PIPE FOR BACKDROP STRUCTURES

Not much to report on the steel mill front, but I was doing some preliminary work on my future sinter plant and thought the technique involved might be useful.   The sinter plant is going to occupy a sliver of real estate against a backdrop and essentially cover up a hole that is needed for access to a concealed section of track.   I'm using the Bethlehem Steel sinter plant as a lose prototype for the structure.   One of the elements of the Bethlehem Sinter plant was a bank of storage silos for raw materials.  Storage silos always make for good backdrop structures as there is rarely a single silo - usually a half dozen or more.  Prototypes can range from glass making, grain, portland cement, coal, sand mining, and more no doubt.     Of course, for the budget minded modeler, PVC piping offers a cheap material modeling and comes in a variety of diameters.    Cutting PVC to length is simple on any chop saw - cuts easy and you should be able to get nice smooth, receptive cuts.    The trick is when you need a half section of pipe.  Cutting this can either be very tedious or very dangerous.    Besides the obvious alignment problems (cutting perfect halves) there is a serious danger of kick-back if you try to cut on a table saw.   There is a bit of tension in the plastic and cutting it can cause it to press against the blade excessively.  


Cutting halves can be a breeze on a table saw.  The trick is turning the round pipe into something with a square section.    The first step is to use a ruler, tape, or easiest, the pipe itself to set the fence of your table saw to the exact outside diameter of the pipe.   Take some scrap 3/4" plywood and cut square pieces - two for each piece of pipe you are cutting.    Using a hot glue gun, glue one of the blocks to the end of the pipe, fitting it perfectly onto the end.  Then place the block and pipe on a flat surface and glue on the other block, using the surface to ensure exact alignment with the level plane.    Now you have essentially turned a pipe into a square block of wood.  

Set the saw blade height just slightly higher than the wall thickness of the PVC pipe and set the fence so blade is exactly centered on diameter of pipe (and width of wood blocks)    All that is left is to turn on the saw and run the assembly through once and then flip it and run it through again.   Since you are only cutting slightly into the wood, the glue and the block will maintain the structural integrity of the pipe until all the cutting is complete.    Just knock the blocks off with a hammer and you will have two perfect half pipe sections.  NOTE - knock sideways with hammer.  Hot glue has a decent amount of tensile strength (pulling object away from glued surface) but not much sheer strength (hitting it sideways)    The blocks should pop right off.


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