|Wire and Insulation fittings|
In the past I have made small pipe fittings that look pretty good. My method is to take a piece of insultated wire, strip off the insulation whole and then cut the insulation into small doughnuts. Sliding these rings back on the wire and secure with super glue .. they give a pretty darn good simulation of pipe fittings.
In the pic to the left you see a piece of #12 NM wiring with the ‘doughnuts’ cut from the insulation (neutral).
|With paint and weathering the finished ‘pipe fittins’ look pretty good. The problem is simply that cutting those little slices of insulation is a pain to get equal thick sections. I assume that a more accurate way could be found . perhaps setting up a single edge razor blade as a chop saw?|
|O Scale 4″ Pi;e|
In 1027 the American Standards Association authorized a committee to standardize the dimensions of wrought steel and iron pipe fittings. What we ended up with are pipes with varying wall thicknesses depending on the Schedule of the pipe . so the ID varies.
From this a nominal 4″ pipe actually has an OD of 4.5 iches. The ID varies – a SCH 5 pipe will have a 0.083 in. wall thickness while SCH 120 has a wall thickness of 0.437 in. For the purposes of my modeling I totally ignore the varying ID and focus on the OD .. that is the part we see on the model. For 4″ pipel then, in O scale that will be 0.094″ OD. Evergreen #223 tubing has a 0.093″ OD and a 0.039″ ID. In metric that is 2,4mm OD and 0.99mm ID.
Since this was the smallest Evergreen tubing I went wtih this and came up with some fittings that would ‘fit’ this tubing. The elebow shown is a good example. As shown, the 2.8mm section represents the boss that I formed using the wire insulation. It is only .2mm ‘proud’ of the tubing OD which in O scale translates to about 3/8″. The 0.98mm stud fits into the tubing ID. Finally the 0.6mm bit is simply a short sprue.
|To test out the concept I created a sprue with 10ea – 45° and 90° elbows, 10ea – couplings and Tees. 4ea gate valves and 4 handles.|
|Everything came out pretty well. I had one piece loose .. the elbow below. It broke at the 0.6mm sprue. That tells me that is just a bit too small. Since the stud is 0.98mm the only reason for that size was simply so it would part from the larger spure easier. The next set if I bump it to 0.8mm that should be fine.|
Here i used teh Evergreeen #223 styrene tubing. At 3/32″ dia it is right at the nominal dia for 4″ pipe. The small stubs sticking out fit inside the tubing.
This is – let’s say .. close to the limit of current 3D printing technology available to the hobbiest. I had these printed in FUD. With a layer thickness of 25 microns it is surpassed by FXD with a 16 micron layer thickness. Still .. worth looking at.
|The gray tubes on either side is the Evergreen 3/32″ tubing. The valve stem is a length of .018″ dia pin and the handwheel is one of the smaller handwheels Vectorcut has in their HO sized Handwheels and Gear set.|