Fixit Log

[Jim]

I would imagine this symptom could manifest in both ways. The cause could be vortex shedding, or it could be the ram pump type water hammer/bernoulli effect as described by Jacob. It depends if there's a moving part in the system, IE a rubber gasket blocking a portion of the pipe that is pushing in and out of flow depending on the water hammer effect/pressure differential in the pipe. Or a check valve that's being overcome and reset at consistent intervals by a pressure it doesn't like, that sort of thing.

[guitarplayer]

Apologies I have only done one year at physics department and even that was at a university rather than a polytechnic or similar (I did though study acoustics).

True that the photo does not show the dynamics of it. That valve is otherwise called ballcock and it is a mechanism identical to that of the toilet flush.

This guy shows how to replace a ballcock and in general this is more or less the setup we have. The noise here was much worse than on the video. At 4:05 he describes the water hammer effect but I don't think this has been my problem in this instance - I think my problem is just that the ballcock is old and water does not go down in a neat flow. It goes down the same way as when you have some old tap outside of an old house and when you turn the tap on water goes in all directions. This I think coincidentally resonates with the pipes to the point where I saw a supporting ring for one pipe broke due to the pipe vibrating (over the years, I suppose).

I did locate a valve upstream and it was fully on - reducing this did help a bit but the stocking is a difference of night and day in comparison.

But yes, we just moved here and when I had first heard it after a few hours of unpacking I thought 'man what a lemon'. However, Evident Rational Enlightenment saved the day.

If water hammer effect is this, we don't have the problem.

That said, I have another less annoying problem in the loft. Every now and again I hear a short noise, also from the water pipes I think, that I will compare to when you have a ruler sticking out off the tabletop and hold it on one end against a table, when the other hand replaces it from equilibrium so it enters the spring-like motion. It then sounds like 'PTIOING' in the first moment. So this is the sound I sometimes hear. It is very irregular so I cannot just hear it and then go to the loft to check it out. I plan to maybe go up there one weekend with a head torch and a book and spend some hours to try to spot its source. I suspect it comes from one of the pipes that exit the water tank onto one of the flats, because of where I hear it most.

[jacob]

If water hammer effect is this, we don't have the problem.

Yes that is what it is. It'll wake up the house.

[Jim]

Here's a decent article detailing the difference between water hammer and resonance. The short explanation is resonance is a function of flow and water hammer a function of pressure surges from shutting down/opening valves. @GP's issue sounds like it would fall under the category of resonance.

https://www.rabielplumbing.com/blog/plu ... is%20sound.

[Sclass]

Huh that video is an ear opener.

I’ve never heard one like that. The stuff in my house is the loud bang when I shut off the valve too abruptly. Or, the transient rattle when I crack the valve open to fast. Thankfully it doesn’t sustain the racket like in that video. That was really interesting. New to me.

I have a valve in the bathroom that puts out a high pitch squeal when I barely crack the valve. It will keep squealing till I shut off the water. If I let more water flow the squeal goes away. It sounds like a trumpet mouthpiece.

Jim’s explanation sounds right. It’s like the hammering effect is causing some kind of resonance that sustains the hammering.

Very interesting.

[Sclass]

DIY wheel alignment. More of it.

I bought some tires this week for one of my cars. Rain is starting out here. At the tire shop the salesman went through the whole "you need to get an alignment to warranty the tires." I don't need one. Yes you do. Look at the wear. Yes, but these tires have 50,000 miles on them, they should be worn. You need new ball joints. No I don't. We cannot align unless you replace ball joints, the left tie rod end and your right front lower control arm bushing. No I don't. Well, we cannot guaranty your tires. Don't, I'll be very careful.

I hate this exchange when I take the cars in. With the exception of race suspension shops, the guys who do tires and alignment are the tech school dropouts. I really don't want them touching my steering adjustments.

So here I am at home and I'd better check my toe in. Of all three alignment adjustments, front toe in is the biggest factor when it comes to premature wear. First, it is the most likely to be out of spec after hitting curbs, parking stops and potholes. Second it goes unnoticed because it doesn't create a pull to one side. It just scrubs away one edge of your tires and kills your mpg. In prior threads I've shown how to do this in a really cheap way. Just get two free tape measures with Harbor Freight coupons and measure the distance between the edges of your tire treads in the front and back of your tire. A partner or thumbtacks help hold things still. It's easy to check and you can get it to under 1mm accuracy if you take your time and average several measurements.

Today I decided to do things a bit differently. I own an SPC Fast Trax camber caster gauge and they have an optional toe measurement. Problem is I bought my set used and it didn't have the toe arms included. They're an extra $60. The story on this gauge is great. The prior owner was a porsche enthusiast who drove his car to the track, aligned for the track, then realigned to drive home. When he upgraded his wheels to giant rims the old gauge no longer worked so he sold it to me for cheap. I drive old cars with little wheels.

But no arms. These are the arms. Just some bars with holes and slots in them. Phooey! I'm not paying for this. I have a pile of scraps to repurpose.

Legit Toe arms from Pelican Parts. No thanks. I have some aluminum angle bars left over from something else. And I have a lot of 3D printer filament.



Voila! The gold part is the existing camber caster gauge. The silver arms are my own DIY creation. Just cut some slots and holes in the angle and mount them with 3D printed copies of the brackets in the legit photo.



Using it. Put two tape measures in the slots on the arms and measure the fore and aft distances between the tires. Subtract. That is toe. I'm about 1mm closer in the front than in the back. Pigeon toed which is just about right for a Mercedes sedan. Of course my car was spot on since last time I did this. The tire saleman is a BS artist who gets paid to upsell you. My tires aren't guaranteed I guess...when I run over a nail I'll do a DIY on how to patch a nail hole.

Measurement. Yes, it's that simple. No laser machine required. A caveman can do it. Eighth grade geometry and subtraction.



Other side of the car.



The arms make this a one person job. Likely more accurate than the thumbtack trick but I've been pretty good with that one too.

Here are some details of the parts. The arms are just aluminum channel from Home Depot. I forgot why I had it but there it is in my scrap pile. The plastic parts are 3D printed. I made a set copied from the Pelican Parts marketing photos but mine are plastic and theirs aluminum so I had too much flex in the white part. I just tripled the thickness and reprinted. Problem solved.



Saw, file or mill the slot. EZ.



I am so done with service salesmen at the shops. They upsell you and get 15% of anything they scare you into buying. I know they have to eat but do it to somebody else not me. It's like mugging - I feel your pain but keep your hands off my wallet. This simple tool keeps them out of my pocket. I checked my paperwork on the tires and lo and behold there were no notes saying I'd not get a warranty because I refused the alignment. I have a full manufacturer's warranty. Of course.

[Cam]

Great write up Sclass thank you. My little car actually might have slight alignment issues so this was a very useful post for me. Anytime I get going over 100km/hour the steering wheel vibrates a little bit. My joke is the car gets nervous going at that speed

I could make this a project for me and my girlfriend to do some time! Although we'll use the two tape measure approach instead.

[basuragomi]

I've used a magnetic level with a built-in fixed laser to project onto walls, which I then wrote on. This had the benefits of being compact and able to align both front and rear wheels with the car centreline, though we had to go back and forth quite a bit. That car also had flat-faced wheels which helped.

[guitarplayer]

That said, I have another less annoying problem in the loft. Every now and again I hear a short noise, also from the water pipes I think, that I will compare to when you have a ruler sticking out off the tabletop and hold it on one end against a table, when the other hand replaces it from equilibrium so it enters the spring-like motion. It then sounds like 'PTIOING' in the first moment. So this is the sound I sometimes hear. It is very irregular so I cannot just hear it and then go to the loft to check it out. I plan to maybe go up there one weekend with a head torch and a book and spend some hours to try to spot its source. I suspect it comes from one of the pipes that exit the water tank onto one of the flats, because of where I hear it most.

It might well be a short version of the water hammer effect when one of the households serviced by the water tank uses one of the taps. I just went up and turned down the valves of all the outgoing pipes from fully open to about 5/6 open (360 degrees turn in the off direction). I am very curious if it will have an effect. We hear those short noises (<1s - 3s) maybe 7 times a day on average so I should be able to notice if the sound is gone or less prominent moving forward.

[Sclass]

Yeah that sounds like water hammer.

Likely the lines could benefit from anti water hammer devices which are these T sections that absorb some energy as the pressure pulse builds up. I’m no expert on selecting and installing these. Everywhere I’ve lived has hammering. What I do know is you need to place them inline with the pipe which may be hard in your situation.

You may be able to secure the pipes to something solid or hang weights on them. The aim is to change the mass of the system. Ideally the energy will dissipate somewhere else in the building like over a neighbors.

[guitarplayer]

Hehe yeah a bit of a hot potato.

I am not going to call the factor to find a handyman (they call them 'engineers' here) to come and fix it - the more life experience I have the more I realise that in this day and age (and societal system of over-engineered solutions?) there is too much of a chance of getting a Cipollian stupid person who will not be able to see the common sense root of the issue, subsequently will make things worse and leave me with a high bill.

I had heard the noise only once and arguably less prominent since my intervention so I am hopeful. Tomorrow I will go up and turn it another 360 degrees down to about 2/3 open.

[Sclass]

Carbon powder and superglue.

I’ve been seeing a bunch of videos on YouTube where carbon powder (graphite, ground battery electrodes, pencil lead or charcoal) is mixed with superglue to create a tougher adhesive that catalyzes rather quickly. There are a ton of interesting videos where the resulting glue is used to refurbish broken gear teeth on plastic gears and glue plates of steel together.

This morning I brought some charcoal briquettes home from the ash dumpster in the park by my house and I started experimenting.

Free charcoal.



I glued a washer to a plate with the charcoal powder + superglue mixture. It’s quite tough. Harder than plastic. And very strong. I was able to pry off the washer but the resulting residue was permanently stuck to the plate. I couldn’t scrape it away with a screwdriver.

I wish I understood the chemistry. I’m adding this to the fix log for future glue jobs. Carbon filled superglue. Now I just have to break something.

[Sclass]

HP 12C calculator repair. I got a really nice financial calculator at a yard sale last week. The guy sold it to me for $5. He said it might have a problem but the batteries were dead so we couldn’t check it.



When I got it home I popped in two batteries and the display came up as gibberish. In other words, predator wrist computer syndrome.



So I took the thing apart and I found this adhesive flat connector between the circuit board and digital display. As I pushed on it the characters came back as something legible. But as I took my finger away it went back to predator mode. I used a hairdryer to heat up the adhesive strip and I pressed the connector back to the board. The idea was to get the glue soft and stick it back on. It wasn’t soldered or silicone zebra stripe. It was just a foil sticker with dried hardened up glue that had delaminated from the LCD.



But this was a recent Gen 12C. I have a 1982 model and it is completely different inside. How HP has fallen. I read out the memory and it was made in 2012 with 2008 software. The original was $150 in 1980s dollars. This new thing from China is $40 (shipped) currently on Amazon. Its cpu is just a blob of black epoxy where the original model had multiple chips. It does do Amortization calculations a lot faster than the old one. My old one flashes ‘running’ while amortizing 30year mortgages for around three seconds. The new Chinese model bangs out the principle and interest in a few milliseconds. So it is technically better but the keys and circuit board is cheaped out. The old keys are multi shot plastic molds that will never wear away. The new one is just printed keys with crooked printing.

So to be fair, it is much less expensive than the OG calculator.

Anyhow the calculator works again. It is in really good condition. Perhaps the owner was a young banker who transitioned to an iPhone app for financial calculations.

[jacob]

Perhaps the owner was a young banker who transitioned to an iPhone app for financial calculations.

Given that it's a new model, maybe a CFA candidate. It's one of only two calculators allowed in the exam. The other is the TI BA2+.

[Sclass]

That would make a lot of sense. He was a young guy and the calculator was for the most part unused. Likely bought to pass an exam then it got put in a drawer where it’s ribbon connector glue dried out.

[white belt]

It may be hard to tell from the photo, but the scissor joint is completely bent to the side. I suspect what happened was that the clips detached from the window at some point due to the friction on the tracks. At that point, the regulator could still move up and down, which meant that the clips could now catch on other pieces within the door and start to get bent out of place. Additionally, another plastic/metal connection point to the door had popped out, which meant the scissor was never going to function correctly. I thought about trying to take out the entire regulator and bending it back into position, but ultimately decided it was smarter to just buy a new one for $40 and install it. It should come within a few days. I also will pick up some more silicon glue for the clips and spray for the window tracks.

So I did replace the regulator but the window eventually detached from the clips again a few months later. Does anyone have any recommendations for how to resolve this issue? I lubricated the window tracks with silicon spray and tried to sand a little of the air strip material off so the windows wouldn't stick as much the first time I fixed it, but it still was enough force to break the clips off of the window. The window is supposed to fall down with the assistance of gravity, but instead it fits so snugly against the weather stripping that it remains in the up position with no clips attached even through hundreds of miles of driving. My next move (unless someone has a better idea) was going to be to just keep sanding down the weather stripping until it no longer holds up the window on its own, then glue the window back to the clips.

[white belt]

I don't plan on buying a new laptop, especially not after spending ~$80 on a new SSD. At some point another component might fail earlier that I can't upgrade/replace. But I hope I can at least make it until the Windows 10 EOL in 2025 because that will also be the 10 year mark.

My old laptop hardware was still going strong, but the screen started to show multiple dead spots. Luckily, DW saved the day because she had an old laptop from 2017 that had a slightly better processor, which is the only thing I couldn't upgrade on my laptop. Luckily I was able to just drop my same SSD in the new laptop with no issues. So after ~$20 to add another 8GB of RAM, I have a "new" faster laptop that should get me to Windows 10 EOL in 2025, unless I require something with even more horsepower than the current 2.7 GHz processor and 16GB RAM setup. For now, I'm happy to refurbish another laptop.

[zbigi]

Speaking of fixing laptops, the right hinge on (the screen of) my 2013 Macbook Pro became really wobbly. The relevant youtube videos said that it's likely that the screws holding the hinge got loose and just need tightening. I disassembled the laptop, detached the screen and learned that both screws actually have severed heads (with the threads still in place). Removing those tiny headless screws is beyond my pay grade, so I started to look for a laptop repair shop which could deal with it.

First two refused (said they didn't know how to do it), but a third guy removed the screws on the spot - sad he's got specialized tools for it. They guy charged me 25 PLN ($6). Now, the issue became how to get replacement screws... I checked 8 repair shops around my city in total and only the eight one had the screws. Apple does not sell them, so they need to be salvaged from junked Apple hardware (they were T8 screws, but of specific length that are only used in those hinges of those laptop models). The store wanted 50 PLN ($12) for them, I haggled it down to 30 PLN ($7). This whole thing felt a bit dystopian - as if they were going to ask for a gallon of gasoline or some batteries in exchange.

Also, the disassembly required detaching internal camera, bluetooth, wifi and screen cables. The Bluetooth&Wifi combo cable connectors (connecting antenna to the wireless card, antenna is actually in the screen, so it needed to be detached) are EXTREMELY finnicky and hard to get plug in correctly. What makes t worse is that the Wifi will work even if you don't connect the antenna correctly - you'll just get much worse reception. And, if you get only say 2 our of 3 connectors right, you'll get decent but not great reception. So, I spent at least a couple of hours playing with those connectors and with a WifiAnalyzer app (which shows the strength on the nearby Wifi signals), until I was certain that all connectors are in place.

[Sclass]

I repaired my Peugeot pepper grinder. It used to look like the blue one on the left but in transparent red. Dropped it during thanksgiving dinner and it shattered. The Mickey Mouse ears just broke off when it hit the tile floor. Sad. We really liked these. So I 3D printed new mouse ears. This is a multi piece print with steel inserts for strength. The shape isn’t really good for 3D printing so I had to make it in three pieces or it would likely break along the directions of greatest stress.



Like everything it took a couple of unsuccessful attempts to get it to the point where I’d be happy using it everyday. Filament is dirt cheap. Each try cost me $0.40. So I’m in about $1.20 now. Not bad. They no longer sell this pepper mill. I think it was a weak design prone to snapping at the top. I have some of the all wood ones that look like a chess pawn that look BIFL but somehow we use these clear acrylic ones more often. When I think about it it’s a miracle that it lasted so long given the high leverage on the ears and the sharp stress concentration right where it needs to be strong.



Also fixed my iPhone screen. Got a used touchpad and lcd online for $20 and swapped it out. I broke the screen when something bumped into my pocket and poked the screen just the wrong way. I only noticed the crack and flickering hours later. Easy fix. DIY Saved some lunch money.

[jacob]

I replaced the home button switch on an old iPhone5. Cost $5 on eBay. No pictures, but this is what happened:
https://www.ifixit.com/Guide/iPhone+5+H ... ment/10594

Only things worth noting is that the switch is glued on with adhesive. The old one was destroyed in the process of removing it. I think it's possible to remove it without destroying it. Also, a J000 driver worked better than PH000 to remove the internal screws. This is likely because the screws were seated with loctite.