Working from Drawings: A Challenge

[Madison]

I thought this might be a fun thing to try. My work of late requires that I produce part drawings that are given to the vendors that produce our parts and, since 488 uses a nearly paperless process during the season, my skills are a bit rusty.

That said, I thought it might be fun for y'all to learn to read drawings and model parts based on them while giving me a great opportunity to learn where and how I can be more explicit so the parts come back from the vendors built correctly. So, I guess the idea here is that I'll attach drawings to this thread every now and again and, if you're interested, I'd like for you to create a model based only on that drawing.

Sounds fun? Maybe only if you're a giant dork, but I'm a pretty giant dork, so.

Round One: 18GA Steel sheet metal part.

[DonRotolo]

Good idea, it'll help ME get some practice using inventor. That'll take a while though...

Spoiler for a clarification of what I am seeing:

I used to think I was fairly competent at this, but I have a question: You spec out in the flat pattern that the bottom 'flange' is 2.21 wide, but the finished bent flange is dimensioned at 2.25. I know I'll feel foolish in a moment, but how do I bend up a 2.25 flange from 2.21 of material? [EDIT] Never mind, I see it now, up top you allow 0.05 for material thickness, well on the bottom you lose 0.01 for the 'bump' so 2.21 +0.05 - 0.01 = 2.25. Toldja I'd feel foolish.[/EDIT]

As far as that whole area, what I think I see is just a 'bump' in the flange, right? That is, the flange is bent up 90 degrees, after 1.25 it gets bent 'down' (away from the viewer's eyes into the page) 44 degrees, then bent back up 44 degrees (net change zero). The drawing of the bent part seems to show it bending up then down though, however that can be a trick of the downloaded image resolution and the interference with the dimension lines.

Don't look at the spoiler if you're going to model this, better you interpret it your way, not mine.

Don

[Madison]

I added a second attachment to the original post that contains a larger look at the end view. I'd have just put the PDF up, but it contains a bit too much information about what this is and who it belongs to

[Pnakovich]

is this metric or english?

[Elgin Clock]

Originally Posted by Pnakovich

is this metric or english?

If it has decimal points in the numbers, then in my experience 90% of the time it's English (or imperial) but that's a good question none the less.

That said, the sheet-metal feature in Solidworks is kinda irritating when you first learn it, (my bends always ended up going in the opposite direction at first) but things like this can be cranked out in no time with some practice. It's actually really cool, the K factor determines what your true radius willl be depending on your final desired angle of the material and the material type.

Good stuff, although to cheat (not that I would ever do that in Solidworks ) I would just extrude the profile and call it a day.. lol

[Pavan Dave]

...I thought too soon when I said it would be neat if somebody would post some CAD challenges... Time to get started!

[Madison]

Originally Posted by Pnakovich

is this metric or english?

English. The title block would explicitly mention this, but again, I can't show that

Originally Posted by Elgin Clock

If it has decimal points in the numbers, then in my experience 90% of the time it's English (or imperial) but that's a good question none the less.

That said, the sheet-metal feature in Solidworks is kinda irritating when you first learn it, (my bends always ended up going in the opposite direction at first) but things like this can be cranked out in no time with some practice. It's actually really cool, the K factor determines what your true radius willl be depending on your final desired angle of the material and the material type.

Good stuff, although to cheat (not that I would ever do that in Solidworks ) I would just extrude the profile and call it a day.. lol

I'm pretty good with the sheet metal features, especially since you can usually just extrude a profile of the finished part and let Solidworks backtrack and figure out what sorts of bends are needed to get there. I have to use the sheet metal features since the vendors like to have the pattern drawings and it's the easiest way, by far, to get them -- though I've seen work by some other folks to get the patterns out that borders between genius and insanity.

[Amir]

If your bend radius in not critical then it is probably better to specify “Use Minimum Bend Radius.” Usually, with sheet metal, the goal is to get as close to 90 degrees as possible. If you specify the minimum, then the sheet metal fabricator will use the tooling set-up to achieve a bend that is as close to 90 degrees as possible without overstressing the material.

If you specify a specific bend radius then the sheet metal fabricator should technically try to hit that radius within your specified tolerances. If you have a close working relationship with your fabricator then they will either know what you are trying to do and just use the minimum or they will call you to confirm. If you just send it out to some faceless shop then they may use your specified radius and this could potentially cost more money.

Using the K factor can be helpful from an engineering design perspective so that you know which bend radius is possible, but putting this radius on your drawing is generally not necessary or advisable.

Hope this helps,

Amir

[Cynette]

A comment on the holes...

I count 8, the description calls out 7 places. I'll admit that I'm not up to date on dimensioning drawings, is this now read "this hole gets this dimension, now look for 7 others and do the same?" Or is the other hole listed somewhere else and is different for error-proofing?

[Madison]

Originally Posted by Cynette

A comment on the holes...

I count 8, the description calls out 7 places. I'll admit that I'm not up to date on dimensioning drawings, is this now read "this hole gets this dimension, now look for 7 others and do the same?" Or is the other hole listed somewhere else and is different for error-proofing?

Good catch. I added a hole to the model after I first dimensioned the drawing and failed to update the note.

[DonRotolo]

OK, now I'm either genius or insane. (Likely the latter)

The bottom 90 bend is "up", the next bend (44) is "down" and the last us "up" again.

But the side view shows these as Up, Up, Down. (CCW, CCW, CW)

Can you help me understand what I am missing here?

Don

[Cynette]

Originally Posted by Don Rotolo

The bottom 90 bend is "up", the next bend (44) is "down" and the last us "up" again.

But the side view shows these as Up, Up, Down. (CCW, CCW, CW)

By Jove, I think you're right! That is how it looks!

[Pnakovich]

so which is supposed to be followed up, up, down or up, down, up

[DonRotolo]

Trust the darwing more than the words. If this was the real world, the guy trying to fabricate a sample, if he couldn't clarify with the designer, wouold use the drawing. Up Up Down until Madison clarifies.

Don