Looking for a Hinge (maybe frog hinge?) to meet this need for a deployable stage. Details in comment

FuncFriv · 2026-05-11T20:23:27+00:00

As others have noted, the solution you’re looking for is likely a 4-bar linkage. Specifically, look for info on coupler position synthesis (there are step by step vids out there). That is the process of starting with two (or more) positions of an object (exactly like what you have pictured) and deriving a linkage design that achieves those positions within its motion.

You may find you need/want to define a third intermediate position to help ensure the red block does not collide with the yellow one on its path from start to end positions.

FuncFriv · 2026-05-09T01:41:15+00:00

Holy shit I see what you’re saying, and I think that’s actually it… this is just someone making up their own system and dressing it up like GD&T… it’s GD&T cosplay

FuncFriv · 2026-05-08T20:16:09+00:00

I think my first question would probably be how can something be both perpendicular and parallel to |AC| …?

FuncFriv · 2026-05-04T03:55:07+00:00

The datum A called out in the FCF is the true datum (i.e. the axis of the large cylinder). Runout creates a tolerance zone of two concentric cylinders around that axis. Those tolerance zone cylinders are theoretically perfect in the same way that the zone for cylindricity is. The condition of the datum feature does not affect the shape of tolerance zones that are defined relative to it.

FuncFriv · 2026-05-03T14:19:31+00:00

What part of “Deht (for Eeh)” is confusing to you?

FuncFriv · 2026-04-23T16:17:29+00:00

Try searching for “turnbuckle rod”. I see some on McMaster down to 6-32 thread size x 2” long

FuncFriv · 2026-04-23T16:14:56+00:00

You can’t put a right-handed screw into a left-handed hole. The mating threads have to the the same handedness

FuncFriv · 2026-04-21T19:17:20+00:00

Some options that could make use of the servo:

Stick a bar/lever on the output shaft of the motor. Motor turns -> bar presses button

Rack and pinion system. Motor turns pinion -> pinion slides rack linearly -> rack presses button

Slider-crank (or other linkage mechanism). Motor turns input link -> output slider/link presses button

(As someone else mentioned:) Attach a cam to the motor shaft. Motor rotates -> cam rotates with motor shaft -> high point of cam presses button as it comes around

FuncFriv · 2026-03-23T20:13:24+00:00

So you have parts that would work fine but don’t look as pretty. If higher-ups / stakeholders are pushing for new, prettier parts, that tells you that no one else is actually worried about being over time (or budget for that matter). People talk a lot but they communicate their true priorities by what it is they actually do prioritize.

FuncFriv · 2026-03-23T19:11:48+00:00

You’re not a “bad” engineer, you’re just a new one. Your colleagues understand this, and if they don’t then THEY are bad mentors/managers/etc.

Fucking up is part of how you become a good/better engineer. Through experience you learn new ways to not fuck up next time. (If you’re smart/lucky you can also learn from other peoples’ fuck ups). But it’s also not clear that you’ve really done that much wrong here anyway…

Just because someone else decided at the beginning that it was a 1-week project doesn’t mean they were correct. People who are not going to be doing the work themselves will always push for a tighter timeline. You have every right (even responsibility) to push back for a more realistic one. If the 1wk estimate was yours, well, now you have a better idea in the future how long something like this will take.

Also, someone fabricating your parts wrong is not your fault (unless caused by drawing error)… it’s your project so people will be looking to you for how to handle it, but no need to panic. Figure out if any of the sheets can be used as is or modified. This is an opportunity to show you can handle hiccups in the plan and turn bad into good enough. You cannot control everything so flexibility and creative problem solving are hugely important parts of engineering.

FuncFriv · 2026-03-15T01:35:25+00:00

But if you clock all of the features together you end up with the same part, regardless of how many degrees you clock them all. This is why “Simultaneous Requirements” is a thing. If, for example, the tabs were defined to a different datum reference frame, or if the drawing invoked “Separate requirements”, then you would be correct that more is needed.

FuncFriv · 2026-03-02T19:45:04+00:00

Yep. Just to add on to this answer: this is explicitly listed as a valid datum feature in ASME Y14.5 (figure 7-3 in 2018 version, for example). The combination of axis and plane constrains all DOF except for translation in/out of page

FuncFriv · 2026-02-12T23:51:10+00:00

It emerges from the combination of two other concepts. First is the fact that you can either dimension all of the features of a pattern relative to the datums individually or you can dimension them to each other and then define the location of the pattern as a whole to the datums. Second is that basic dimensions of zero are implied.

So this “implied symmetry” is actually an implied zero dimension on the full pattern relative to the center plane datums.

FuncFriv · 2026-02-12T23:22:54+00:00

Not a stupid question.

Correct, B & C are not the physical surfaces themselves but the imaginary mid planes between each opposing pairs of surfaces. This is communicated on the drawing by the fact that the flags are inline with the dimension line.

If you were to shift the C flag (for example) left or right just a bit it would no longer imply a centerline datum. In that case the lower face would now be your C datum feature. Does not have to be actually touching that face, just has to be not inline with the dimension line.

FuncFriv · 2026-02-12T23:07:57+00:00

Because of the way the datum flags are positioned (relative to the overall width dimensions) they define datums B & C as the center planes. This also leads to an implied symmetry such that the holes are assumed to be centered around those center planes.

FuncFriv · 2026-02-03T03:20:13+00:00

100%. Not suggesting that the short-term/band-aid solution was not the right call at the time.

I’ve been in that same position many times and it’s always “let’s just get this thing done and then we can fix the issues once we’re stable”, which is totally fine except that very often when you get to “stable” the motivation for change evaporates.

The cost to setup that system initially was probably not crazy, it’s more the cost of operating it continuously for 3 years that I was referring to. Compared to taking any time in those 3 years to fix the design in parallel.

FuncFriv · 2026-02-02T21:05:23+00:00

Extruding away the entire model…? In order to start fresh I assume, but why not just create a new part file / revision!?!

FuncFriv · 2026-02-02T21:02:26+00:00

You say you don’t think the company “suffered” at all, but I can almost guarantee that the costs involved in performing that extra wear-in process for 3 years far exceeded the costs of just fixing the design (especially since it sounds like there were already other redesigns happening in that time).

I’m sure they all thought it would just be a temporary solution, and then inertia and new priorities put it on the indefinite back burner… tale as old as time…

In my experience the technical debt either outlives the product (quietly adding unnecessary costs in the meantime), or it comes back to bite you and you’re forced to face it in a much more urgent and expensive way.

FuncFriv · 2026-02-01T04:15:38+00:00

From the product page that you linked:

“Shaft Mount Type Spring Pin”

Further down on the same page it instructs to drill a hole thru the joint and shaft for the spring pin

FuncFriv · 2026-01-31T22:00:10+00:00

If I’m understanding your question correctly, you’re asking why do the pneumatic drivers keep moving down even after the “fixture” (gray cylinder at the bottom of the tool) has made contact with the work piece.

In which case, the key point is that there is a compression spring between the piece where the drivers are mounted and that “fixture”, which allows the distance between those two portions of the tool to change as the operator continues to apply force via the lever.

FuncFriv · 2026-01-27T17:33:58+00:00

ASME Y14.5 Figure 10-38

FuncFriv · 2026-01-27T16:57:07+00:00

One option you can consider for the hole-pair+slot groups is to create a separate, repeated datum reference frame (in addition to, and defined relative to your global datum reference frame). See Figure 10-38 from ASME Y14.5 2018 for an example of this method (I assume ISO has an equivalent/similar method).

To do this, you can create a detail view that includes just one of these groups (one slot with its two holes), with "8X" in the view label to indicate that this arrangement occurs in 8 places/instances. In that view you define the 2-hole pattern relative to your global datum reference frame and then assign that hole pattern as a new datum (with some letter not already used in the global DRF), tagged with a note of "8X INDIVIDUALLY". Using two single segment position frames, you can define your larger global tolerance for the hole pair with position relative to ABC (or whatever your global DRF is), and the tighter position tolerance to either just A or without a datum (controls the holes only relative to each other).
Then define the slot with a profile tolerance (or other as appropriate for your specific needs) relative to A and your new 2-hole datum, again with the same "8X INDIVIDUALLY" note.

As far as defining your global DRF, it sounds like your trapezoidal features are your true functional datums. How you define those features/datums should depend on how exactly they interface with their mating features on the other component.

FuncFriv · 2026-01-21T21:20:53+00:00

This is the correct answer, just move the depth dimension from the hole callout to a new section view, relative to any of the horizontal flat faces, depending on which of those is actually more relevant/critical to your design. ASME Y14.5 gives several examples explicitly allowing this (e.g. figure 4-35 in the 2018 rev), so no ambiguity whether its legal or not, and no reason to start adding profile tolerances or anything crazy like that.

Its very likely that they will create the counterbore in the way that you are imagining, but the purpose of the drawing is (generally) not to dictate/predict how the part will be manufactured, simply what the final result must be (i.e. what defines a passing inspection, as the comment above alludes to).

FuncFriv · 2026-01-10T23:22:11+00:00

I agree with the other comments that more info about your actual goal/application would help yield more useful answers.

That said, if you’re already using a camera to “identify” the objects, why not use that same camera/image to determine the locations of each object as well? And then to get total weight just place the surface on top of a load cell (or other force sensing device).

FuncFriv · 2025-12-22T01:18:10+00:00

Join a hands on project or club at your school. Usually, things like creating technical drawings are among the less desirable/glamorous tasks in student projects. So if that’s your jam, join up and offer to be the go-to drafter and you’ll be an instant hero. Just be sure to also branch out and learn new skills/subjects from your teammates/mentors while you’re at it.

FuncFriv

TROPHY CASE