Tolerances a bit tight or what?  

You get that (or worse) all the time when you just accept the defaults for a new drawing. Those of us who have used CAD for a while don't fall for it. For a start it makes your drawing look horrible. :)

My Dad was an engineer. In retirement, he got back into motorcycles. On more than one occasion, he's drawn up a bracket or plate he needed made, and I was first in line to source materials and make it for him. He drew up the part, all the measurements for me.

But, it would be based some crazy material size like 7mm steel plate, or needed a length of 9.2mm steel rod. I had to explain that there is no such thing as 7mm plate or 9.2mm rod, he needs to design it based on available material sizes, like 6mm plate or 10mm rod. The typical engineer vs fabricator discussion. He once asked if I could mill thicker plate to 7mm. Its a bloody bracket to hold a GPS!

In many industries the builder has to spend a lot of their time redesigning the engineers work to suit what material sizes are actually available. I've been involved in many meetings where new plans come through and we spend days fixing them so its can actually be manufactured without costing a fortune.

Glenn

That’s a freshman engineering mistake!

Oh yes, been there...  :)
I was somewhat naive in mechanical engineering when I started designing control panels. I've had quite a few visits from the metal shop lads saying "we can't make it like this, will this work?". lol

You make the piece with 1 relevant digit, and use a big hammer to make it fit.

Volhout

Yep, that's the way. The correct use of the percussive adjustment instrument. :)

  Gizmo said  

He once asked if I could mill thicker plate to 7mm. Its a bloody bracket to hold a GPS!

G'day,
This became more prevalent as less people with real world skills on the shop floor where allowed into the office.

Part of my job over the years at several companies was as a "sanity check" on the engineers designs before they where finalized. It is amazing how often the need for a "strongly worded discussion" with someone who cannot see sense because they have never operated a lathe / mill / folder / guillotine / brake press / welder etc. Also trying to prove that something that works on CAD will not work in the real world for reason X.

Not knocking most of these people, very smart and on a lot more money than I'll ever be, but a lot had very high skills in a very narrow area.

Good to see the slot is for a 1/4 bolt  

Regards, Lyle.

It doesn't only happen on the practical side. The number of times I've had to change drawings so that they can be printed... When will people learn that you can hardly see yellow ink on white paper? I eventually changed the default yellow to a "dirty, printable yellow" on my machine. It wasn't difficult.

Oh, and red is a dark colour that doesn't show up all that well on CAD systems with a dark background, but perhaps I'm being unfair on those who only use Mac systems. ;)

Stuff like this is part of the fun and entertainment working with and guiding (university level) students. Add to this the joy of them working almost exclusively in metric, although much of materials in North America are dimensioned in inches. 7mm plate? No, but you can use 1/4 inch.

Plus many have just learned about machine tools such as milling machines, so they are ready to mill the bajeesus out of slabs of, say, stainless steel to fabricate a prototype structure. We might explain that it will be expensive, time consuming and have a high probability of failing because the material will warp.

Fortunately, _some_ of them learn...

  PhenixRising said  

  Gizmo said  

He once asked if I could mill thicker plate to 7mm. Its a bloody bracket to hold a GPS!

GPS = Global Positioning Satellite. Do you know the weight of this satellite ? Maybe 7mm is not enough, and it has to be 0.5"      

Volhout
Edited 2026-06-19 16:15 by Volhout