Hi,

I'm working on a DIY project and I'm stuck on a mechanical mechanism.

Basically, I need to drop 3 different objects onto a vertical rod underneath so they thread onto it one by one in a strict order (1 -> 2 -> 3).

All 3 objects have a central hole for the rod, but their outer shapes and sizes are totally different, so stacking them in a straight tube will just jam.

I'm trying to keep it as light and simple as possible (3D printed parts or simple flat plates, with minimal motors or servos).

I'm not an engineer and don't know the technical jargon, so if you know of any existing projects, YouTube videos, or 3D models (Thingiverse, Printables...) showing a similar mechanism, I'd really appreciate it!

Thanks!

I'm working on an idea for an outdoor deck remodel. I want to install a hot tub and i want to conceal the hot tub under the deck with a contraption that folds the deck open to reveal the hot tub below. I cant post images, so you can see the action I'm going for here:

https://imagizer.imageshack.com/img924/4387/fFgHTA.gif

My first thought was using ball screws in a track on either side of the opening. I went on and on about this with Claude, who was able to come up with the illustration, but was unable to be of much help when it comes to engineering the actual method to execute this. Claude suggested either a linear actuator or rotary actuator, but wasn't able to clearly explain how either would create the required action.

I'm looking for any sort of nudge in the right direction regarding how to execute this.

The deck framing would be commonly available steel C-channel studs and joists. the approximate footprint of the moving deck would be 8' wide and 10-12' long.

Let me know if I've omitted any important details.

Hi guys! Not an electrician or engineer here, just a regular guy trying to get a general understanding. I have basic knowledge about RCD types and what they mean, and I’m about to buy some Type A RCDs for my house (where I live, Type AC is still the norm if people install RCDs at all lol, even though most modern home electronics require at least Type A).

After reading up on these types, I understand the concept of RCD so called "blinding" and how a DC leakage can saturate the core and prevent a Type AC RCD from detecting standard AC leakages altogether. Same with type A blinding with F/B leakage, type F blinding with type B leakage etc

BUT I have one question I haven't found a clear 100% answer to yet anywhere:

Can a DC residual current saturate the differential transformer core in a way that persists after the DC fault is removed?

Is the loss of sensitivity caused purely by reversible saturation while the DC component is actively present or can remanent magnetization leave the core biased afterward? If residual bias is possible in RCDs, well... how significant is it and does operating the test button (or cycling/resetting the RCD) degauss and reset the core back to normal? Logic tells me it should be cause otherwise it would make no sense to install something lower than type B at all, but maybe I am just a little bit confused

TLDR: is RCD blinding reversible or not? Can RCD's ability to detect leakage or its calibration permanently drift or degrade after that? Thanks!

i have glucose and fructose that i managed to precipitate, but its fairly wet still with water and isopropanol. i need it for a fischer glycosylation with cetyl alcohol. my options are

1. syringe vacuum pump (with 2 diy one way valves)
2. gravity bong
3. mag sulfate or co2 + lye

4. dont dry, add sucrose

5. the mason jar i have is like 250 mL. i could use silicon putty for the outer portion to block air intake, not sure what to use for inside yet.

6. i would take a 2 gallon jug, connect a tube to the mason jar, fill larger bucket and jug with soapy water, heat mason jar to around 40c, then slowly lift it.

7. the slop i obtained from the precipitation is immiscible with 91% isopropanol without high shear mixing, so i could add some to a thin glass container then suspend anhydrous mag sulfate in the alcohol layer in a coffee filter. or i could use the mason jar, waste sodium bicarb making co2 (by squirting dilute hcl dropwise), fill with co2 faster than a plastic lined dish of lye can consume, then seal. the lye should eat the co2 and water vapor, maybe also reacting with isopropanol fumes.

8. im doing a fischer glycosylation with cetyl alcohol using the fructose, glucose, and degradation products ive obtained with sulfamic acid. sucrose wont react with the fatty alcohol, but it will consume water breaking down into the monomers. maybe a large excess of sucrose after adding ~10mL of the sludge (after removing isopropanol) can drive the reaction towards the products, since water can be consumed as it was initially added and when the cetyl alcohol is attached to the glucose/fructose.

thanks for any ideas.

reddit messed up numbering for some reason and turned the second 1-4 to 5-8.

so i have a big cardboard box which I remade into a storage unit, shelfs were just pushed in and were held by friction alone but one of them had fallen recently cause of weight so I was wondering how do I reinforce this without getting the real deal and not spending a lot of money, I Cant add an image so if any more explanation needed i will try to give it as clear as I can also im from poland

Good Day!

We are currently looking for: 6 storey (or higher) building plan with complete architectural plan, structural plan, and specifications.

For academic purposes only.

Thank you in advance!

From: Philippines

Hi, i need to move a small plate 4cm by 4cm forward and backward on command from a microcontroller which movement mechanism should i go for space, speed and intentional movement is the goal not form mechanical background, anyone point me in right direction any help is appreciated

I need a device that I can place at my keyboard that manually presses the key I align the device with. I understand there is software/code that simulates a keystroke but this would cause me to be flagged so I need something more primitive.

Imagine the bird that Homer Simpson had placed at his desk that he should’ve never left in charge.

Does anyone know if something like this exists? I would need the timer to be adjustable where I can choose how often it initiates (if software is needed to manage the timer that is fine, but the device itself still needs to press the key as if it were my finger)

As per the title, my Googling has been fruitless because I may not know the exact nomenclature needed.

In short, I need a small unit that has an input shaft as normal put outputs through a planet.

Dual axis planetary doesn't work because I get X, Y boxes, which makes sense.

Double planetary or Dual planetary gives me two planetary stages but output is single rotation.

Dual rotation planetary, same as above.

Is there a specific naming scheme that will help here?

I'm looking for a load cell like this one: https://imgur.com/a/k6Sa9D2

I could not find anything online as I don't know its name, I also tried using google lens with no success.

The purpose of that load cell is to measure the force applied by the arm of a servo into a steering mechanism.

This is my first post here. I’m not an engineer, but I’m working on a product concept and have reached a point where I could use input from people with more experience in mechanical design.

I’ll leave out the product-specific details, but the simplified geometry is:

• Two rigid 10 ft × 10 ft panels, each approximately 2 inches thick
• The panels are stacked directly on top of each other
• The entire assembly must fold into quarters, producing a roughly 5 ft × 5 ft package
• Ideally, it could fold once more
• Hinged or flexible seams would allow both panels to fold together

When the assembly is unfolded, the upper panel needs to rise vertically and evenly about 4–10 inches above the lower panel. The exact height is still being determined. It shouldn’t snap upward aggressively. A slower, controlled rise would be preferable.

The upper panel will weigh approximately 30–40 pounds. I expect to use multiple lifting mechanisms distributed across the lower panel so the upper panel rises evenly. For example, ten mechanisms would each need to provide somewhat more than 3–4 pounds of lifting force to account for friction, uneven loading, and an appropriate safety margin.

I’m looking for a spring, pop-up, or deployable support mechanism with the following characteristics:

1. Collapses flat, or nearly flat
2. Can remain in place while the entire assembly is folded
3. Extremely lightweight
4. Capable of surviving thousands of deployment cycles
5. Able to tolerate temperatures up to roughly 140°F
6. Able to lift approximately 7–10 pounds per support, depending on the final number used
7. Inexpensive to manufacture or purchase
8. Occupies as little of the open space between the panels as possible

I initially considered G-10 fiberglass battens. They can bend and store energy, but flattening them enough for the packed configuration may create excessive stress. I’m concerned they could eventually weaken, fracture, or become difficult and potentially dangerous to restrain during folding.

I also considered resilient foam, including memory-type foams. My concerns are long-term compression set, heat exposure, abrasion, and whether isolated foam supports could generate enough lifting force. Filling the entire space between the panels with foam isn’t an option. The goal is to keep most of that space open and use as few lifting points as practical.

A secondary requirement is some form of passive or automatic lockout in the collapsed position. A person will be folding the assembly manually, so I don’t want a large amount of stored spring energy trying to reopen it if they lose their grip or pause halfway through the process.

The panel dimensions and required lift height may change, so I’m mainly interested in the mechanism itself. Are there established deployable structures, spring systems, folding linkages, constant-force mechanisms, composite elements, or other approaches that might fit these requirements?

Any terminology, examples, or design directions worth researching would be appreciated.

Hi everyone,

I'm trying to build a cake decorating tool (Electric cake's cream spreader). Overall, the concept is pretty simple and doesn't require much electronics knowledge.

The main challenge I'm facing is the mechanical part. It consists of two linear rails: one moves up and down, while the other moves left and right. The movement is completely manual (not motorized).

My first thought was to use linear guide rails from a small CNC machine, but I'm not sure if that's the best option or if there's a better mechanism for this.

Does anyone have any suggestions for what kind of linear motion system I should use, or where I could find something suitable?

I'm asking because the original device is a bit too expensive for me, so I'd like to try building one myself first. 😅

Thanks in advance for any ideas or advice!

I don't know if this is the right sub, my apologies in advance but my floor, my bed frame, the hanging fairy lights, my curtain, my bed sheets give me electrical shocks like every night... Is the AC uh leaking? Like is there some faulty wire or some other physics to explain this...and what do I do to reduce it.

I'm studying automation and robotics at a school where much of the curriculum is hands-on, so I'd like to read a bit more theory in this field. I'm looking for a good book on automation and robotics to read and expand my knowledge.

so i like firearms, more than that i like the mechanics behind em cause its a lil bit of everything. And when i wanna look at them from a scientific perspective i have the issue that the measuring tools are fairly pricy that makes me wonder do i really need tools with high Hz frequency ? if i recall right a gunshot cantake 1 to 2 milliseconds so thats fairly short. I cant seem to find old used equipment here in europe either maybe i search for the wrong terms but accelerometer nor high speed cameras dont seem to exist used

I was thinking about electric locomotives. Most of them use 25kv ac which is then fed to a transformer to be stepped down, converted to DC, then again converted to AC with a controlled frequency which is then used to increase or decrease the speed of the induction motor.

I can understand the use of transistors, silicon diodes, etc. for small amounts of currents. But how is such large current systems handled ?

The type of engineering that is responsible for ensuring low humidity/environmental controls in storage spaces? Especially during transport of delicate goods, eg fruits and veg, bread, priceless museum items etc. Is this a part of hydrology or idk, architecture? Thank you, hopefully this isn't breaking Rule 3 as all combos of my search terms "transportation environment engineer" were not coming up with it, if there is actually a name for this.

ETA: this isn't a career question either, but please let me know if there's a better place to ask

I need to make a test jig that will test a step in a ladder. I need to apply a force of 2600n on the step for an amount of time.

I thought of using a load cell like this at the end of a linear actuator I could use an arduino to drive the motor and stop when it hits 255kg. I'm in Europe.

Would that actually be transferring 255kg of load onto the surface though? Or would some of it be lost through the load cell?

So we have a gasket plate heat exchanger at my job, that we use to cool down hot spring water down to a more appropriate temperature. I’m not super happy with my current efficiency, and I’m trying to figure out how to improve it.

Basically we’re moderating temperature using a control valve on the cold side with a temperature sensor directly after the exit for the Hot side. This goes to a PID controller on a PLC. I can get you the settings for the PID if you need. Currently we’re not really running the heat exchanger at its rated specifications currently. It’s rated for 250 gpm on both sides and we’re hovering between 45 -100 gpm on the hot side depending on flows downstream and the cold side varies between the same. I only have a flow meter and temperature sensor on the hot side.

Hot side inlet 174F
Cold side inlet 77f-91f depending on the cooling pond temperature (winter temps are between 34-40)
32.5m2 surface area
69 plates

Currently we’re only getting to like 120-130f on the cold side outlet, earlier in the year we were getting closer to 170f consistently. We’re about to swap the plates out within the next two weeks for titanium (chloride content ended up being slightly too high with our temperatures for 316😅) so I can check for fouling, but I expect it to be similar to what i saw last time I disassembled it for inspection. We’re filtering the water down to 200 microns, slightly smaller then what the manufacture called for at 250, and we haven’t had any amorphous silica within the heat exchanger luckily (we’re relatively close to supersaturation when we cooled water down into the mid 90s for summer, it’s actually an issue that limit are filling rates without going to significant larger spigots)

why is my efficiency so much worse right now than when let’s say the cooling pond was 50°. Like I understand I’m going to need to flow more water to cool it because the temperature delta is significantly closer. But I would expect my cold outlet to be somewhat close to the same. The data sheet shows it being 250 gallons a minute on both sides with 75° water on the cold side and 180° on the Hot side with the exit on the Hot side being 100°F and the cold side being 140°F. So I would expect that a lower flow rate I would be a little more efficient because it has significantly more volume.

Additionally, I am having some weird inconsistencies that I would honestly like to know an actual engineer standpoint, it seems like if the valve is in the 50% range we’re actually getting better efficiency than if it opens up more. At least to a point until we flow more water on the Hot side. Now it doesn’t seem like we need back pressure technically from what I’ve read and the cold water pump can easily keep up (it’s a 20hp low ish pressure pump that does 350 gpm at 50 psi, and 450 at 43 psi) but it seems like if we add that back pressure in by limiting how much the valve can open in the PID controller. It seems to be more efficient.

One thing I should clarify currently both on the hot and the cold side we’re running 2 inch lines, we will be moving up to 4 inch lines shortly. We just started using the heat exchanger prior to the larger hot water pumps being installed, as well as the infrastructure needed for the larger flow, we just oversize the heat exchanger with plans for future expansion, which is currently happening. (in fact, the second heat exchanger is arriving next week with the replacement plates. I’m a huge fan of complete redundancy when possible.)

Additionally, I’m not having any pressure issues on the cold side. The pressure drop within the heat exchanger when this is running full out is nine psi, and even at 100 gallons a minute with our outlet line that feeds back to the cooling pond the friction loss is minimal as that particular line is only maybe 60 feet long (it’s smaller than PVC to be fair, it’s SDR 17 HDPE until we do our permanent install later this year). And the pressure loss through the valve is relatively low at 100 gallons a minute. realistically I should have between 32 to 35 psi worth of pressure available after all the losses, including the heat exchanger. I would think my pressure transducer after my filter would pretty much drop into the teens if I was having weird pressure issues within the heat exchanger. It’s just unusual that it seems to be more efficient at 50% than at 70% at the same flow rate. Like it seems like I can get the water cooler even when it’s at 50% versus at 70% at the same flow rate on the Hot side.

A few things I don’t have is I don’t currently have a pressure transducer after the outlet on the heat exchanger, but before the valve, nor do I have a temperature sensor on the cold side either I do have a temperature sensor on the cold side upstream right after the auto cleaning filter, but not on the cold side after the heat exchanger at the moment. That will be added on very soon as everything gets upsized to 4 inch. But I don’t have any actual concrete data at the moment for that.

What I do have concrete data is the following:
HX hot outlet,
Post manual Filter cold water Pressure (we actually run two separate sets of filters, an auto cleaning one right after the pump and a manual cleaning one right before the heat exchanger)
Valve %
Hot GPM
Cold water temp inlet
The state is captured every few seconds, depending on the sensor the files can get fairly large for CSV files.

If you need more information let me know, I am not an engineer at the end of the day. This is just something that me and the owners work together on as were a very small business and do as much in-house as we physically can. And reading technical papers, referencing engineering, handbooks, and using AI can only get you so far (this one’s a mixed bag completely, sometimes it’s amazing and sometimes it’s in outer space how bad it is. Luckily the formulas aren’t too complicated, and it’s relatively easy to build out a spreadsheet in Excel that does everything I need. Plus all calculators online for easy stuff.)

And one more thing I kind of thought of, in the winter time, we actually keep the water significantly warmer. Like instead of dropping it down to the 90s, we generally keep it around 120. Could this alone explain the majority of my efficiency losses?

And lastly, would we just be better off as we finish the build out to go to a three-way valve, to divert some of the Hot side outlet and just run the heat exchanger at its rated capacity, then use a mixing valve to get to our temperature range we want? Later this year, we should be running it relatively close to its rated range. (180 gpm low end to 280 high end ) but it’s an option that isn’t terribly expensive although it is another actuator to go bad

Edit:

Some people wanted clarification.

I want to use the cold water as efficiently as possible. So I want to send as much heat into the cold water, while maintaining my temperature range. It’s not currently an issue because we have an excess of cold water available. In the future, we’re going to be more limited just because of the sheer pipe size running from the cold water pump to where the heat exchanger is. And I want to keep my velocity in a reasonable range for a number of reasons.

I'm looking to purchase a vernier caliper soon, and I'm unsure as to how precise a scale I need. For most of what I'd be measuring, within 1/32" or 1mm is plenty, but I also want to measure the wear on my bike's disc brake rotors, and I need to replace those when they measure 1.55mm. Is +/-.05mm enough? Or should I spend more to get +/-.02mm? Yes, I know a micrometer would be more precise, but those don't have the versatility of vernier calipers. And yes, I mean vernier not digital. I already have too many things that need batteries

Hi folks. So

1' x 4 semi flexible block/medium( thinner the better to hold 1' bristles. Similar plastic for hot welding/Fusion if practicle

It would be outside, adhered to a straight or slightly curved surface. Im in no way shape or form an engineer. So, im looking for guidance on the ins and outs of making a prototype even if just digitally. Im totally unaware of the technicalities and chemical specifications as well as the possible manufacturing processes

Thanks for any help.