Monday, April 26, 2010

Process and Instrumentation Diagrams-P & IDs.

You can have too much of these. I've been doing a few in the last week or so, and I'm just about all PIDed out. Where I'm working they don't have a standard, so we went with a bunch of symbols that the engineer liked the look of on a previous job. He did not particularly like the ones that I have posted on my site at

There seems to be all sorts of ways of doing a valve unsurprisingly: the ones on my site have little bits of line on the ends of the valves, and they have actuators built in. On his ones, the actuators come as a separate block. Some of them have invisible attributes, some don't.

They are also plainly "old autocad" in that there are no dynamic blocks at all. I have not been a fan of dynamic blocks for normal drafting, but I think they might be the best for PIDs.
If I get enthusiatic enough, I hope to post a set that could do pids.

It looks like a fertile field for lots of lisp macros. On that springs immediately to mind is a routine where you specify 2 points and a line is drawn between the two with maybe a continuation tag at one end and a valve in the line, already inserted.

You can pay for such things, but it seems most people don't, preferring to slog it out with plain Autocad.

There are all sorts of ways of doing pids- I like the tanks drawn in a heavy line-the engineer likes them in grey or very light so that the lines are the emphasis.

Anyone interested in a CAD standard? I have a very lightweight one that just covers the basics.
Maybe next post......

Thursday, April 22, 2010

Video Driver for Autocad Fun...not

As always with a new version of Autocad (R2011) , it is a good idea to update your video driver.
I am lucky enough to have a quadro FX1500, so I duly updated it.

Somewhere along the line, and I'm sorry I cannot remember the exact sequence of steps needed, this all came unstuck. I had text that disappeared after moving, slow everything, viewports that went all funny. Just beore I thought to blame Autocad, I decided to check 3dconfig. There it had a choice of 2 drivers- One Autocad and one that looked like an invdia one.

I changed to Autocad and all was fixed.

Hope this helps someone!

Saturday, April 17, 2010

The disappearing draftsman, slips and trips, and DS and DIMLO

First, The Disappearing Draftsman. Last week I had an interesting viewpoint explained to me by an engineer I'm working with. He had gone ahead and done his own PID's, but needed me to knock them into shape so that they would be presentable, which took a day to do. I'm not sure how long he spent on them, I would imagine at least 4-5 days.

He explained that he found that he could use Autocad as a faster, easier way of producing a sketch of what he wanted than doing a hand sketch. Plus there was an added advantage that the draftsman was only required to do a short "tarting up". The last place he worked, there was a proper drafting department, and they were probably grumpy that he was doing part of their work.

Here at his new work, there is no drafting dept (only me, 2-3 days a month!). So he has to manage somehow.

I have done a few PIDs, but would hardly call myself an expert, so I was interested to hear his take on how they should be done. He reckons, at the quotation stage, you just insert symbols, and leave it at that. You do not use symbols with lots of hidden attributes so that at a future date you can extract a full Equipment List from the job.

The generation of tag numbers, he said, should be the preserve of the Electrical guys, who make a large database. When they have done their thing, and the job is a go, then you can put the tags on.

Slips and trips: I recently had a reasonably complex design to draft. It was a "bag massager".
I came unstuck in one of my drawings: the 20mm plates welded onto a 100x100 axle, somehow got moved by 100mm, this was only in the detail drawing- the main ass'y drawing was correct.

Which made me think: could this have happened in Inventor? Probably not. But I'm stuck with Autocad, so what could I do to prevent this happening again? My only idea is that I make it policy with any assembly to xref in all the parts.

DS and DIMLO: Yet another engineer, at a different plant, has arrived, and he seems keen on doing his own drawings. That is OK by me, because less time working=more time living. He seems pretty good, just a little polishing required in the dimensions department. Namely, he had large arrows and tiny text on his dimensions.

I explained to him the system I use-but I'm not sure he was at all in favour of it, which is to use 2 lisp routines, DS.lsp to set the text height and DIMLO.lsp to insert, then erase a block that has most dimensions styles a mechanical draftsman might need.

In the past done I have done things differently-see a previous post about zero height text.

Here are the two routines:


;This routine sets up for text to be right height
;By Bill Le Couteur
(defun c:DS()
(setq skale (getreal "Please enter the plotted scale: "))
(command "-style" "STANDARD" "ARIAL" "0" "1" "0" "" "" )
(tblsearch "style" "R1")(command "-style" "R1" "ARIAL" "0" "1" "0" "" "" ""))
(if (tblsearch "style" "R1-25")(command "-style" "R1-25" "ARIAL" "0" "1" "0" "" "" ""))
(if (tblsearch "style" "R2")(command "-style" "R2" "ARIAL" "0" "1" "0" "" "" ""))
(if (tblsearch "style" "R5")(command "-style" "R5" "ARIAL" "0" "1" "0" "" "" ""))

(setvar "MIRRTEXT" 0)

(setq the_textsize (* skale 3))
(setvar "textsize" the_textsize)
(setvar "dimassoc" 2)

The nice thing about this is if you have an existing drawing an someone has used the style R5 say, then you can change that at the same time as well.

Here is DIMLO.lsp

;This routine sets up for dims and text;
By Bill Le Couteur
;imports a dummy block containing a set of dimension styles
(defun c:Dimlo()
(command "-insert" "c:/cad/library/symbols/dimension styles" "0,0" "1" "1" "0")
(command "erase" "l" "")

A very simple routine-I have no idea why Autodesk don't have a magic button that does all this...

Of course, many will argue that you need to set up your prototype drawing nicely, with all the needed scales and the text the right size, and this is correct, except what happens when you change scales? As well, if you purge the drawing your nicely setup scales that are not used are ditched, so if you want to use a 1:20 dimension style, it won't be there.

Sunday, April 4, 2010

Autocad 2011

There is not much point me going into the user interface etc etc as you could go to, say,Robin Capper's excellent blog at where he does a good job of giving a run down on R2011. You might have to reverse through to the post, as he seems to be churning them out!

So, I'll just outline my experiences with it and hope that someone gets around a few of the things that I found as I proceeded to waste my Easter weekend drawing a set of instructions for a do-it-yourself cabinet assembly.

On firing up for the first time I noticed: No toolbars. Well, it turns out that they are still there, just hidden-I guess that Autodesk want you to move towards the Ribbon system. Here is a snip of my screen setup, just of the ribbon, shown vertically as I have two screens:

(By the way, there is a snipping tool in Vista-look under Accessories)

How to get your toolbars? Just to the right of the Quick Access Toolbar there is a small triangle.

Press this and locate "Show Menu Bar". Then go Tools/Toolbars/Autocad and tick the ones you want.

Another fun annoyance, was the helpful popups that appeared in the top right hand corner.

On pressing "Don't show me this again" it appeared yet again, and again. A friend told me that they were all different ones and that after a while all sorts would be eliminated. Makes sense, really, because you want your new users to be looked after.

A lot of new changes are not immediately apparent- for instance the loft command has been overhauled to allow for surface creation. Previously, the dialog box came up automatically, now you have to use the Settings option to make it come up.

As usual with new releases, I tread carefully, making sure I do regular backups.

The neatest things I'm finding are:

*The materials system has been overhauled and is looking good.

*Hatching has had a lot of work done on it and seems much better.

*Polylines are a lot nicer to edit - but old habits die hard!

*There is a new display bar on the right of the screen which has the often used orbit button on it, and the "Steering Wheel" which I have not been using but have been driven to because of it's handy little button marked "Center" which is great if you want to reset the orbit center graphically.