The Vemco Drafting Machine

This is a design setup which was used by Dave Salyer in the aerospace industry before CAD in the 1980's,
He shares his experience-

The machine that has the track running horizontally and vertically is a Vemco Drafting Machine. We could draw lines anywhere on the board and make them parallel or at an angle of our choosing.

The head of the Vemco machine is rotatable and graduated, but most of the time, we used triangles to draw angles at 30, 45, 60, and 90 degrees. I preferred not to have the vertical scale (aka ruler) and only used a horizontal one since my vertical lines were done with a triangle. This is because the vertical scale would get out of calibration (loose screws) very easily and you couldn’t trust it.

We would mount a vellum sheet on the green surface you see here. We used masking tape in the corners to secure the paper to the table surface. The green surface is actually a silicone rubber sheet that has just the right amount of give for our pencils to make crisp, clean lines. A hard, smooth surface is not good to draw on. In the old days, people would draw on soft wood boards that would have to be sanded down every now and then because they’d be grooved, so these resilient sheets were state of the art at the time.

The vellums were typically ANSI B, C, D, E, or F size sheets. Sometimes, we’d have roll-size H or J vellum and we’d have to roll each end up so we could work on a section of the roll at a time.

Circles were drawn with templates preferably if we had the right size, otherwise we’d use a compass, which really took a lot of practice to master.

I’d always practice my important circles/arcs on scratch paper before darkening in. It could ruin your whole drawing if you didn’t get it right.

For all other lines, drafters would use a “lead holder”, which was sort of like a mechanical pencil, but it just held a thick graphite rod. We needed to put a point on that to make our lines the right thickness. These are still common today because they make great sketching pencils.

When we drew our lines with one of these, we actually rotated the pencil as we drew so the lead would wear evenly as the line was being laid down. It took me a while to get used to that and still draw a straight line.

There was an art to putting that point on and we were taught to use sandpaper to do that, but later I learned the pros would use a lead pointer attached to the end of their Bruning electric eraser. I splurged and bought a new one for $100 at the time.

Yes, we did lots of erasing so we had to have one of these. We didn’t have a MOVE command back then, but we did have an ERASE command!

To do precision erasing, you needed a shield like this:

Back to drawing lines and selecting leads. Selection of the right lead for the job depended on the task. If you were doing construction lines and “lightening in” object boundaries and guidelines, you would use a 6H lead. You wanted to lighten in your complete drawing and dimensions because if your design changed or you screwed up something, you might have to erase a lot and re-draw; 6H lines disappear easily and completely if they aren’t “darkened in”. Measure twice and darken in once.

To draw centerlines, you’d use a 4H lead, pretty sharp. I like my center lines very thin while also being super dark. Hidden lines would usually be a 2H, and object lines would be H. Lettering could be an H, but a lot of guys liked to use F or HB, as it was less fatiguing and didn’t require so much force. But those leads broke easier and the graphite smeared easier, so I usually used H.

On rare occasions, we did inking on mylar, but that was only for special circumstances. I still have my Staedtler Mars ink pens that cost me a small fortune back then. We also did what are called “wash-off” mylars, where a vellum drawing is reproduced and printed on mylar with black lines that can easily be erased. We used special pencil leads made for drawing on mylar and special erasers that could erase without taking the matte finish off.

Think of wash-offs like opening a drawing and doing a Save As, then making a few edits to the drawing and title block, and then releasing the new drawing in 1/10th the time. Wash-offs were as close to CAD as we got back then.

We were taught to use drafting dusters, which put little tiny eraser balls on the drawing. The dusters looked like a sewed up sock and they were good for cleaning the smudges off the drawing.

The little balls helped our tools glide across the surface without smearing. But I learned that the real pros used these very little. The truth is that if you used too much, it would actually slightly erase all of your lines so you’d have to go back over them so they’d reproduce better in the blue line or black line machines (copiers). If you lettered with nothing softer than H, you wouldn’t have a problem with smudges either.

We always kept one of these handy too:

In the 80’s, the Pentel pencil was becoming very popular and it improved drafting quality because you would pick a lead that was already the thickness you wanted for your lines and you didn’t have to make a point just right each time. We would use 0.3 mm for center lines, 0.5 mm for hidden lines, and 0.7 mm for object lines and lettering. We would still use our lead pointers with 6H lead for doing guidelines and layout work though.

Lettering was usually done by hand but on some projects, the client (U.S. Military) insisted on stenciled lettering so we did a lot of that. It slowed us down a little but honestly, once you get used to it, you can letter pretty quickly with a good stencil and a Pentel pencil.

So that’s how we did the drafting. I will say that back then, we had to use our minds to visualize designs and the exercise of doing that forced us to be more focused on the concepts. There might be one layout of the design and it would be a primary elevation or section view of the assembly. You had to know what you were looking at to project the geometry in the other directions in your mind and then go to the drafting table and draw those parts in 3 or more orthographic views.

Scaling was a pain. You were blessed if you could draw at 1:1. So many errors were made back then because someone was drawing at 4:1 or something and they forgot to multiply or divide by 4 or whatever.

This was also an issue in the early days of AutoCAD because there was no Paper Space back then. You had to decide what takes precedence, the model or the paper. At first, we chose the paper because we were paper drafters after all, but later we realized it is easier to scale the borders and annotations but leave the model at 1:1 and plot the drawing at the paper scale. But oh, were you in trouble if you had mixed scales on one drawing!

The biggest drawback to hand drawing was not that we didn’t have beautiful, rendered 3D views of our models. Everyone had a picture of the model in their heads already so that wasn’t a problem. The drawback was when we needed to make a simple change it was a monumental effort or a big risk. You went back to the layout and salvaged what you could, you did calculations by hand and marked up all of the affected drawings and sent them back to drafting to incorporate redlines. You wouldn’t truly know if you did all this right until the parts were made. Because of this risk, a lot of designs were simply left alone if they would work like they were, knowing they could have been done better if we took the time to make the change and do it right. Better was often the enemy of good enough. CAD changed that for sure.

In 1985, I started doing AutoCAD on an IBM-PC XT computer. It was very unnatural for me and many of my colleagues at first. I wasn’t drawing on the board for long (4 years) so I converted pretty easily but some of the old timers back then never could get used to CAD and were happy to finish out their careers and head on into retirement without ever learning it.

We had a 640x200 (CGA) color screen but I’d rather work on a Hercules Graphics Monochrome display with 720x348. It was tough to do complex layouts this way but I eventually managed.

A lot of people couldn’t get used to doing layouts in AutoCAD and did their design by hand, only using AutoCAD as a drafting tool once the design concept was laid out. But all that changed when we got a 14″ color monitor with 800x600 (SVGA) resolution, as we could appreciate layers better.

By 1988, we had display list processors, 19″ CRT displays, and 1024x768 resolution so we were loving it. I never did a drawing by hand again, including layout work, unless I had to dig a vellum out for a direct vellum change on an old drawing.

That was a trip down memory lane for me.

I hope this gives a little feel for how things were in that era for the curious and nostalgic.

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