I am going to be referring a lot to the text on Jig Box etc. but am going to try and parse it down quite a bit.

  • d is a jig box, about 5 feet x 7 feet
    • Ummm .. no. I ended up fitting the Jig Box to the Jig Tank. I ended up with a larger Jig Box measuring 61.92″ (5’2″) x 107.616″ (8’11”)
  • is fitted into the jig tank e by metal plates on the four sides of jig tank and on jig
    • red plates attached to the Jig Box and green plates attached to the Jig Tank. These plates seem to me to be \frac{1}{2}" thick. If you have one plate on the Jig Box, one plate on the Jig tank and leave the thickness of a plate for clearance then you have \frac{}{}" space on either side between the Jig Box and Jig Tank – meaning make the Jig Box 3″ shorter both in width and length than the Jig Tank.
  • This jig box has a reciprocating movement and is worked by double eccentrics f and g keyed to shafting, lying parallel and geared into each other to run at the same speed
  • The jig box is hung from fg by eight rods h
    • The rods are 1″ diameter. The nuts up top are 1\frac{1}{2}
  • The coal after passing through c is at once immersed and goes through a complete disturbance from eight to ten times before it reaches the point of discharge for the coal j and for the slate k
  • The box has, in the bottom, perforated plates that slope to the front end where there is a sliding gate l.
    • This is a 4.2° degree slope. I doubt seriously if it matters re:the sliding gate that much if you will even see it in the model. Possibly from the outside to the front. If I build it .. will just be for the “fun of it”.
    • I noticed that they say .. “The box has, in the bottom, perforated plates…” … plural ‘plates’. Huh. Sounds like these plates drop into a recess. Note that there are those tooth looking pieces hanging down from the bottom of the box.
  • The tank is bushed in on four sides with iron plates to fit squarely against the same character of plates on the jig box, giving the result of a practically tight joint, but at the same time giving the jig sufficient play so that it can be moved up and down by the eccentrics f and g hung on the two pieces of shafting just over the jig
    • Plates are shown – Red plates attached to the Jig Box and Green plates attached to the Jig Tank. Notice that the Green plates are larger. The plates look like they are \frac{1}{2}
  • As the jig box goes down, the water is forced through the perforations in the plates with sufficient force to carry the coal of a certain specific gravity up and over the lower end of the jig, the water being sluiced through an open trough to the settling tank or basin o
    • Again .. mention of plates plural. Note that they can’t just drop in place as the pressure from water being forced through the plates would dislodge them if simply dropped in place.
  • The slate gate or refuse discharge l is raised and lowered at will by the lever m
  • The opening at k is adequate to pass a 4-inch cube, and is the entire width of the jig
    • Again .. not going to show unless I build the Jig Box dry and empty. The scaling of the plan shows about a 5\frac{1}{2}" opening … pretty close IMO for scaling the drawing.
  • the lever m is fitted to a radius of a half circle with slot to accommodate the opening and shutting of the gate l, and is fitted with handscrew so as to enable the setting of this gate at any height
    • Lever m and the handscrew will be visible and obvious .. attention needs to be paid to that. Note that the operator needs to be able to get to this lever .. and handwheel so .. steps, walkway etc. needs to be included in the design.
  • The coal, after having been separated from its impurities, passes over the top of the jig box d and out to j, into what is termed the settling basin n, where it is allowed to settle to the bottom, there being very little disturbance of the water in n


From this point on I will mostly be using mm in 1:48. There are a couple of reasons .. (1) Jumping between Full-Size and 1:48 always means a chance of error so keeping to mm means less chance (2) All of my 3D CAD is in mm – actually what I call pmm = Pseudo mm – basically I model with Model Units set to Decimal Inches with the “Display units format” un-checked (3) actually model ‘as if’ I am modeling in mm. If I were to model a cube measuring 1″ on a side I will then model it in pmm at 25.4 per side. What this does is let me model 25.4 x actual size which solves problems Sketchup has with radii below 0.018″. (4) CAD for 3D printing is much easier as I can just “Export STL” with Export unit set to Model Units which both Shapeways and my printer accepts as the model in mm.

Jig Tank/Jig Box DIM

Getting a handle on things. This may have to be revised at some point but the ‘plan’ such as it is (with all due respect to Robert Burns: “The best laid schemes o’ mice an’ men / Gang aft a-gley.”) .. still .. these are the dimensions I will work from.

  • I show the boards making up the Jig Tank wal\ls as 3″x12″. This being an O scale (1:48) model this is simply using \frac{1}{16}" x \frac {1}{4}" stripwood. The Jig B ox I showed being constructed with 2.4″x12″ boards.
  • Sitting here on a cold Thursday morning with my first cup of coffee it occurs to me that here the KISS principal may very well apply – it would make little sense for the workers constructing the washery to order boards from the sawmill with one group planned 3″ thick and the other 2.4″. With that in mind I have changed all the boards to the 3″ x 12″ \frac{1}{16}" x \frac {1}{4}" stripwood.


Here’s what I will call a “near Finished” version of the Jig Box. Making a claim that it is actually ‘Finished’ would be a mistake as such a statement will bit you in your backside very quickly. The detail is a bit excessive .. some of the bolts and such are simply too small to replicate in 1:48 but it doesn’t hurt. They are also part of the process to locate exactly where the nuts and bolts logically go. This is true of the other parts such as the refuse gate mechanism, the corner reinforcement, the perforated plates (I made them more of a grille. That may change).

Honestly .. I just like creating things in Sketchup and I get a bit OCD ..

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