Builders Work Drawings

Any consultant working in the construction industry should be aware of all the other services present on site. To co ordinate this, the principle agent will co ordinate services. However, in order to accommodate the services in the structure, "builders work"drawings are issued to instruct the builder as to what openings are required in the structure. It is vastly preferable to plan for these openings, rather than to create holes in the structure after construction is complete. However issuing a 2D plan requires some understanding of what is going on. Horizontal penetrations require invert levels (the height of the pipe from the finished floor level) as well as width and depth sizes. Vertical penetrations also need to be carefully dimensions so that they fall exactly in the correct location. It is also important to note that the builders work drawing is taken from the soffit of the floor below to the soffit of the existing floor. ie. if one was standing in a building, say on the 1st floor, with the builders work drawing for the first floor, all of the vertical penetrations shown on the drawing would be through the slab you are standing on, and all of the horizontal penetrations through the walls surrounding you would show on this drawing. However any vertical penetrations in the slab above would show only on the drawing above.

This can be tricky when checking penetrations on site, as when the beams and slabs are cast, the horizontal penetrations through the beams will show, as well as the vertical penetrations of the floor above. Thus one would need to refer to the floor below's drawing when checking horizontal penetrations through the beams, and the current floors drawings when checking the vertical penetrations through the slab.

Designing a duct system

So recently I was tasked with designing a duct system for a small dental practice. I learnt a few things that bear repeating. The terminals where ceiling diffusers, so I set about selecting them, looking for which sizes would best suit my flow rates. However I ignored the fact that at these differing flow rates, the diffusers would have to be adjusted to varying pressure levels. Now in a system where all the terminals have balancing dampers, its OK for you to have differing pressure drops in your diffusers, but as was pointed out to me, if I have a diffuser in one room with a low pressure drop, and another in the next room with a high pressure drop, the flow of air will tend towards the lower pressure, and your flow rate there will increase, while your flow rate in the other diffuser will decrease. Thus when designing a system, it is important to insure that all your terminal outlets have similar pressure drops, unless there are individual balancing dampers at each outlet.

CAD tips and tricks 4

So I recently opened a drawing where the UCS was set at a very awkward angle, and tried rotating and redefining, and all sorts of things to get it right. Turns out there is a simple answer to the problem, just type in UCS in the command line, and then use your cursor to designate three points to where the UCS should be. Its almost too simple to comment on, but since I found lots of ways not to do it, I thought it was worth the comment!

CAD tips and tricks 3 - Text Frame

So sometimes its good to have a frame around your text, to highlight it from the surrounding text. I searched high and low for how to do this, thinking that it must be to do with Mtext options. However the only solution I came up with was to use a multileader and to remove the arrow. you can do this by hovering your mouse over the endpoint of the multileader, and a text box will pop up with 3 options, one of which is "Remove Leader" once selected this leaves you with text in a frame, that will update accordingly if you edit the text!

CAD Tips and Tricks 2 - Rev Cloud

So while trying to find out how to make my revision clouds look the way they are supposed to, I discovered a nifty trick that when creating revclouds, one can select an object (ie a polyline) and change it into a revision cloud. No more messy revision clouds for me!

Valve Types

While at a training session recently a valve type was mentioned that I found unfamiliar. Here is some clarification:

Globe valve - this is a valve which is named for the shape it used to be constructed in, round like a globe. I was confused as to what the difference between the Globe and Ball valve was, as I would image the similarity in names. however the globe is named by its OUTSIDE shape, whereas the ball is so named for it inner shape. the flow is controlled by a ball with a hole in it, when the ball turns, so flow is restricted. In a globe valve, there is a chamber, which has a physical partition in the middle with a horizontal plate with a circular hole in it. A cylindrical plug is what causes the reduction in flow, which will be controlled by a screw in manual valves, or an actuator assembly in automatic valves. The plug moves perpendicular to the flow, coming from the wall of the pipe to the centre of the chamber, to sit on the plate when the valve is fully closed.

CAD tips and tricks 1 Publishing

So recently I had to print a whole batch of drawings to pdf at one time. It took a long time, but afterwards I was told this trick. The publish option in AutoCAD, which I have never used, can be used to print multiple documents at once to pdf, DWF and to the plotter that is specified in the page setup of that drawing. This means you don't even need to have the drawing open to plot it, you can insert it into the publishing sheet set, and the publishing option will print it automatically. This has already been a great help to speed up the process when printing multiple documents, especially when they need to be printed to pdf!