r/AskEngineers

Hey everyone,

I'm trying to make a pressurized container (~12 psi above ambient air pressure) to store tennis balls in to stop them from depressurizing. My current setup is a 3 inch diameter PVC pipe with a cap on one end and a screw on cap on the other end. There is also a spot to pressurize it with a bike pump.

My issue is that it leaks air out past the threads. Right now I'm just using teflon tape and tightening it by hand. Is there a good way to make an airtight opening in PVC that I can unseal and reseal by hand?

I'm a commercial HVAC service technician and have recently acquired a blower assembly out of the dumpster for a laminar flow hood I want to build. It's a double shafted, 3/4HP, 1075RPM motor with 2 separate scroll cages and wheels. Unfortunately the units data plate was worn off or otherwise lost in the dumpster so I don't know what model it was to get the manual and fan curves.

I know the flow hood will be operating around 1" wc static pressure, but I don't know what speed I'll need to get the correct CFM for the 100fpm velocity for laminar flow. While disassembling and cleaning the 2 halves I had a thought.. What if, instead of buying a direct replacement double shafted motor, I buy (x2) 3 or 4 speed motors and run the airflow in parallel. I would wire them so I could run them at the +- 1 speed difference (i.e. Lowest speed: 1 fan low speed 2nd fan off, 2nd lowest speed: both fans low speed, 3rd lowest speed: 1 fan low speed and 2nd fan med speed, etc.).

My question is how well would running 2 blowers in parallel work if they're not operating at the same speed? Would the pressure difference at the different outlets cause air to flow backwards through the slower fan, even if they're just 1 speed different? Should I just stick with a double shafted motor so they're running the same speed? Am I just needlessly overcomplicating this design as I am want to do?

Anyway, thanks in advance for any insight or advice you can give me.

I'm in software and know enough to be dangerous in general engineering but very much a dabbler. I have a german sheppard with pretty bad hip dysplasia and arthritis. She is on puppy pain meds and is generally still a very happy and playful girl. She sleeps upstairs in our bed.

She is beginning to have problems coming down the stairs. Her back legs will splay and she will backup and not go down the stairs. It's was once in a blue moon but now is maybe once a month. It's only going to get worse.

I'm looking for some engineered way to get her down the stairs. She is about 100lbs and carrying her is not really an option, my wife isn't big enough to attempt. I'm 6'3 so in theory I could but I had a kidney transplant now I'm on more or less permanent weight restriction on lifting due to some issues from the surgery.

Now I have a classic northeast home built in the 20s. So narrow steep stairs with a 90 degree turn at the bottom and 2 staris. She can handle 3 or 4 stairs no issues so it's the initial 15 that's the problem. I'm thinking maybe some sort of track system but not exactly practical for the wife and I to use the stairs. Then I was thinking maybe some sort of elongated dolly with treads. In a perfect world the side would be open and just use a dumb waiter style thing BUT the stairs are enclosed in basically a hallway.

So I'm open to any suggestions people might have. She's only 7 so probably has a couple of good years left, I'm flexible on budget would prefer diy. I'm fine with power tools and good at soldering (although I doubt that is helpful here). I have 3d printer and am happy to have something machined if I need to. I appreciate any thoughts you all have. TIA.

Been integrating Claude Code into our engineering workflow for a few months. Started noticing the costs were higher than made sense for the tasks we were running so I actually sat down and traced what was happening.

For a straightforward refactor task, rename a hook across a few files, Claude Code runs Glob to find the files, Grep to filter, Read on each file individually, Edit on each file individually, then Read again on each to verify the edit landed. That is north of 10 API calls for something that structurally needs 2. And each call re-ingests everything before it as input tokens so the cost compounds across the session.

I started benchmarking specific tasks before and after any tooling change. Same prompt, clean state, real API usage fields, not estimates. The turn count gap on complex multi-file work was significant enough to change how we structure sessions.

Curious whether other engineering teams are actually measuring this or just absorbing the cost and moving on. Would be interested in what numbers others are seeing on real workloads.

Howdy gang,

To avoid XY problem, my use-case.

I am an exceptionally tall person and I compete in target shooting. Rifles generally do not accommodate my shoulder width of "length of pull" - and the desired length I need between trigger and butt pad is over 17", most rifles cap out at 15".

To overcome this, I have replaced the bolts that hold on my butt plate with longer ones, and turned up some spacers that are essentially washers with a couple inches of thickness.

This means the rifle no longer fits in any hard case without being dismantled, and the bolts attach by threading through the butt pad, a plate, and into the stock where they thread into a floating barrel nut. The assembly chews up precious range time, and I'm hoping to find a better way to set up and break down.

I had thought that there might be something out there like those spring-loaded toggles you get on coats, but instead of locking down on some cord, it has some threaded(?) jaws that engage under spring tension, but can be detached easily - bonus points if it stays in the hole without needing three+ hands to assemble!

Of course, any other ideas would be welcomed!

Your comments on my previous post inspired me to investigate further. Proper tools. Meticulous photographic documentation at every step. Timestamps intact.

Gearbox accessed.

I expected yellow lubricant. Maybe brown. Coffee-colored at worst.

Negative.

The failure-state sludge (black/grey metallic marbled appearance) was significantly darker than anticipated. If it weren’t observed in a food-and-beverage appliance contamination event, I’d almost call it pretty.

Is water ingress through a failed seal the likely mechanism — water breaches first, lubricant follows the same path upward into the auger zone, and abnormal wear begins from there?

Or does lubricant breach first, with the appearance change occurring after water exposure and mechanical breakdown?

Photos available if desired.

Sample submitted to an independent laboratory today.

I also received communication from the company again. They stated I should receive a report by the 22nd. I hope so.

When I first registered what I was seeing, my immediate thought was:
“Dear Saruman,
I found your Mordor Nutella.
Looks delicious. Tysm.”

Hi everyone,

I work in an industrial belt in India and currently deal in industrial lubricants and oils as a distributor. Recently I’ve been noticing a possible gap related to hydraulic oil and lubrication oil filtration services, especially external/offline filtration.

Around me there are thousands of industries consuming large volumes of hydraulic oil, gear oil, cutting oil, etc. Many machines already have inbuilt filters, but I’m still hearing about companies doing additional external filtration or kidney-loop filtration.

I wanted to understand from people actually working in maintenance/reliability/hydraulics:

- How common is external oil filtration in real industries?
- Which industries use it the most?
- If machines already have onboard filters, why do companies still use offline filtration units?
- Do companies usually handle this internally or outsource it to vendors?
- Is contamination really such a major issue in hydraulic systems?
- Does filtration significantly extend oil life and component life in practice?
- What are the biggest challenges in this business/service?
- In your experience, do smaller and mid-sized factories ignore oil cleanliness compared to large plants?

I’m trying to understand whether this is a serious reliability/maintenance practice or more of a niche activity.

Would appreciate honest technical and business-side insights from anyone involved in hydraulics, maintenance, reliability engineering, steel/paper/plastics/forging industries, etc.

Thanks.

I am looking to reduce the solid length of magazine springs without significantly reducing it's cycle life. Pistol magazine springs are a rounded square, oval, or triangle with different sized coils so I can't use a general online calculator. I've already wasted a spring company's time with 1 bad idea and wanted to check if this makes sense first before taking it to them.

If the dimensions of every other coil are reduced to allow them to nest into the coil above, will this noticeably reduce the cycle life or tension of the spring? The general dimensions of the springs are around 1" x .5" with a wire diameter of around .050-.055". Most of the springs have between 8 and 15 coils. I will like to be using stainless steel, but if music wire will deal with the compression better I will use that.

Edit: I am asking about changing the OD, not the wire thickness.

As far as my understanding on the subject, I have used every technical term I know in this post already so if you tell me I need to calculate the magnetic resonance frequency at 26*K or something, I'm already lost.

Watching the Space X launch and landing which is from a control technology standpoint of course quite impressive I suddenly asked myself the question from the title.

Why carry fuel up and down to save what amounts to little more than a tube of metal alloy with a computer and an engine. Isn't payload the most important criteria and wouldn't using retroburning to brake hurt double since it has to be carried up to be used? Is the tech in the rocket really that expensive to warrant this?

We are trying to cover decks for refinishing them during rainy weather. We are looking to use something like 1" emt (there seems to be lots of manufactured couplers available)

Is 1" emt strong enough for holding a tarp up spanned across a deck? Lets say supported with an upright tube every 10'x10'

hello y’all I’m new to all this shortcut/difficult words/internet stuff

id like to know what a DNS, IP ADDRESS AND VPN’s are.

not completely new either but I would like to know how all that confusing stuff work.

If this subreddit isn’t the right place to ask can you please link or just say on what I should post all this.

Thanks for the help (not posted yet but I thought it would be nice to add the thank)

i also searched the internet for over an hour so I hope this respects the rules

Edit: automod said I had to specify what country I’m in, for privacy reasons I will not say exactly what country, but I can say I’m from the northwestern part of Europe (Great Britain, Ireland, Belgium, the Netherlands, Luxembourg, Northern France, parts of or all of Germany, Denmark, Norway, Sweden, and Iceland). although I could be more specific

I need a masters that pairs with my Bachelor's degree in Computer Science for the accelerated 4+1 program. I like both of these tracks but have concerns for both. For robotics, I'm afraid I'd be pigeonholing myself into a career. I'm not that strong at C++ and it seems interviews are heavy in that regard. Computer Engineering seems more broad and like it would provide more choices but it's relatively the same as my undergraduate and I feel like I should do something different. Please advise.

Hello everyone,

I’m a junior mechanical engineer seeking guidance from experienced professionals in maintenance and reliability.

Could you share insights on which types and sizes of mechanical seals are most critical to keep in stock for emergency and preventive maintenance?

Edit: Based on feedback, I’m focusing more on identifying critical pumps first and then understanding the seal requirements for those specific assets.

I’m particularly interested in understanding what is commonly required in real-world operations.

I am looking for a material for a 0.3mm-thick clamp. The clamp was previously made of clear anodized aluminum, but it wears out too quickly. Therefore, I am looking for a substitute material with the following characteristics:

• Final Product Color: Matte White / Matte Light Silver
• Hardness: 50 HRc or higher
• Young Modulus: 190 GPa or higher
• Naturally electrically insulating, or electrically insulating finishing / treatment

I am looking for a vacuum pump/blower to transfer biogas from the storage bladders to our mini flare. We have a research-scale anaerobic digester (3000 gallons) for aquaculture waste solids at my organization, and can produce up to 350 cf/day of biogas (currently around 35 cf/day due to low solids concentration). We have a small ATEX/C1D2 vacuum pump that can only transfer around 0.5 cfm, but we need something that can handle 15 - 20 cfm, so we can flare large volumes relatively quickly (we may buy another flare if necessary). I have often seen regenerative gas blowers being used on farm-scale digesters to move the biogas to the generator/flare (not sure if they use ATEX/C1D2 rated equipment), but I cannot seem to find something suitably sized for our scale at a reasonable price (under $3000). An ATEX/C1D2 liquid ring vacuum pump could be another option, based on my limited experience (research background, limited industrial experience). There might be other options too, but I am not sure. Do you have any suggestions or vendors I could reach out to for my application needs (preferably US-based)?