Unsatisfied !?

[kwoodhands]

Many years I built a locomotive that was supposed to run on steam. The boiler drove me nuts, fix one leak and another appears. Finally I decided that this is not fun anymore and ran the locomotive on compressed air. Runs great, but is a show piece on a shelf .
Several months ago I decided to build Rudy K tractor. I started with the boiler. 1-1/2" copper pipe and bronze for the heads.
First try held water but I did not do a hydro test because the boiler looked lousy to me. The water tubes are external and they were the problem. Water tubes were so bent up that I started over again. I used this boiler to experiment. I found a better way to install the tubes. Second boiler held water so I did a hydro test. Water tubes held , backhead leaked immediately . I cleaned the joint and tried again, failure. I decided to cut the backhead off and examine it. I immediately saw what I had done wrong.
I use Harris black flux for hard solder. I use Castrol tapping fluid for tap and threading parts. The Castrol was put in a pill bottle , it is black and looks the same as my flux.
Both are in pill bottles and look the same. I felt like an ***** and made a third boiler. Tapping fluid is a lousy flux as I found out. Made third boiler. Tested 60lbs. pressure and held for 30 minutes. Boiler runs at 30 lbs pressure when running.
This boiler passed the hydro test, I took the wife out to dinner to celebrate.
I rarely give up when a part is made wrong. Proof of this is a box full of " experimental " parts.
Now I am making gears for this tractor. Total of 9 gears. This the first time making gears. First five are made and mesh well. I make two sets of gears, first set in Acetal. Lot cheaper than brass. If all goes well the second set will be brass. So far so good.
Not perfection , but well satisfied so far.
mike

 

[master53yoda]

My son and I have had this discussion a few times. He is a precision CNC machinist we agree that the level of perfection should be based on the function of the part, I cast and machine so my parts are never to the perfection level that he is used to. He has worked on things like the optics ball on the AH64 helicopter gun ships. He also brings up that some times the tolerance levels set by the engineers are not attainable with the machines unless they are machined in a progressive tool path without any reverses in direction.
Art b

 

[jmille7916]

Unsatisfied ...
When making an engine and especially with engines with many parts , many cylinders,, sometimes there is one or two parts that I really don't like - due to a small mistake or carelessness or even poor machining. ... , it's still usable but I'm not satisfied
Use it or will make a new one!? That's a question I often ask myself
I always want it to be the best it can be, but there's always something I don't like
Have you ever been like that ? And what will you do ?
Thanks !

 

[jmille7916]

My son and I have had this discussion a few times. He is a precision CNC machinist we agree that the level of perfection should be based on the function of the part, I cast and machine so my parts are never to the perfection level that he is used to. He has worked on things like the optics ball on the AH64 helicopter gun ships. He also brings up that some times the tolerance levels set by the engineers are not attainable with the machines unless they are machined in a progressive tool path without any reverses in direction.
Art b

Many years ago, the good people at Princeton designed and built a fusion machine, designed to achieve the conditions called breakeven This is when at least as much energy is generated as used to achieve the fusion. The problem was that when this was achieved, then things would be finished for this machine, since the meutron flux developed would make various components sufficiently radioactive that they could not be handled. In the end noone did the final experiment because there was always something else that they wanted to try.
Moral is to set your goals as you wish, but to remember to follow through to your own satisfaction

 

[Steamchick]

Hi Bluejets,
I have amended the old adage "Measure twice, cut once." into: "Think first, then think again, then Measure twice, think again, cut once. - Add to scrap bin, think again, then do it properly!" - Maybe even "repeat"?
But I am an old Engineer.... and often think something can be better instead of "adequate"...
Many so called "Designers" simply copy "previous" designs with a few tweaks, - To suit available (or affordable) materials, machining methods, personal skills (expertise in various ways), etc.
The worst cases are when someone simply "(linearly) "scales-up" a previous proven safe design. e.g a 3" boiler "scaled-up" to a 5" boiler.... AAAARGH! - Design calculations involving squares, cubes, etc. CANNOT be scaled linearly. I have experienced boilers that were "scaled-up" from maybe an 80psi NWP to be used as a larger boiler - but only meet NWP of 20psi (or less) when the calculations are conducted.
So the first "Think" must be "is it a correct design?"
My first experience of this (as a 10-year-old) was to double the dimensions of a balsa framed tissue covered glider design.... Not only di I need about 8 times the nose ballast the get the C-of-G where the centre-of lift was, but I needed a large ballast weight adding so it would fly. The ratio of thickness to lift to length of an aerofoil is very complex and non-linear, (including the magic Reynold's number!) and way beyond the linear scaling of a 10 year old. - so I had generated a glider with far more lift than suited a practical flying speed - and when it was finally ballasted correctly to compensate for the huge lift, it flew so far it smashed into trees a few hundred yards away...
So I worry at machinists who simply "linearly" change the size of models....
So please include the "think, think, think again" bit to your old adage.
K2

 

[Gabe J DiMarino]

Many years ago I was told .What makes a good tool maker is if you make a mistake being able to fix it .Fix it in a way no one can tell it was fixed ! To me it makes more sense to save a part . Granted there are times when you have to start over . A part has 3 functions .FORM ,FIT, FUNCTION ... Dose it look good ..Fit dose it mate properly with other parts in the assembly . Dose it work as intended . If any of these are not meet and you cant make it work .Well I guess you need to start over .

 

[Ken I]

If you can't fix it hide it !
The toolroom I was working for at the time bought a brand new (and very expensive) Swiss jig boring machine and set it up in its' own air conditioned room.
It was given over to the tender mercies of a toolmaker who had developed multiple sclerosis and worked mostly out of a wheelchair.
On his first day on the new machine he drilled a hole in the table - he figured he's be fired for sure - what to do ?
Plugging and machining would be obvious so he did something daring - He counter bored the hole, drilled thru and tapped for an oiling nipple and very carefully stamped "oil" next to the hole.
I noticed it and thought it was an odd place for an oiling nipple ??
So it came to pass that the bodge went unnoticed (but frequently oiled) until the toolmaker 'fessed up at his retirement party some eight years later.
Most of the party traipsed down to the jig borer and sure enough the oil went nowhere other than the sump.
Even the manufacturer's service personnel did not notice (or kept mum about it).

 

[Lloyd-ss]

Many years ago I was told .What makes a good tool maker is if you make a mistake being able to fix it .Fix it in a way no one can tell it was fixed ! To me it makes more sense to save a part . Granted there are times when you have to start over . A part has 3 functions .FORM ,FIT, FUNCTION ... Dose it look good ..Fit dose it mate properly with other parts in the assembly . Dose it work as intended . If any of these are not meet and you cant make it work .Well I guess you need to start over .

"Damn, I was afraid that was going to happen."
"Damn, I can't believe I did that."

Being able to fix your blunders is BIG.

 

[minh-thanh]

Hi All !
So many comments, so many stories ...
Very interesting .
Thanks a lot !

 

[awake]

I have slept on this and given it more thought,, so a second reply.

Although I haven't been working on engines very long, pretty much everything I make, now and for years previously, is a Design-Build project.

I rough the design out in cadd, and then proceed. During and after the build of each part, I keep an up to date AS-BUILT drawing. Does that mean that all my parts are perfect, LOL.?

Yes, absolutely. The plans match the parts perfectly! (Who says it has to be the other way around? )

My frequent motto: I've cut this board three times and it is still too short!

 

[Rocket Man]

I am a projectionist, I want engines to run good but I don't care if they win the ugly contest.

The first engine is a 1"x1" steam or air engine. It runs 40 to 1000 rpms. I have pullies to power other things. It has collected dust & rust in the past 30 years. Block is a 2"x2"x4" piece. Head was a scrap piece I never even machined it to fit.

The red flywheel engine is 6 cylinder steam or air. It runs 30 to 600 rpms. The .312" dia. pistons need to be larger but it runs good.

For each his own. Do what you like, and have FUN. Don't worry if people laugh at your ugly engine. LOL.

 

[Brian Rupnow]

All of my engines are beautiful----to me. All of my engines are machined to the absolute best I can give. All of my engines drive me a little bit crazy. I am a much better machinist now than I was thirteen years ago when I started this foolishness. I have become very good at hiding my mistakes. I learn as I do. I don't often make the mistakes I used to make.---I make new and different mistakes.

 

[Shelton]

This is wonderful thread with lots of good philosophies mentioned. All good ones, too!

 

[D and D]

I believe the saying is "Strive for perfection and settle for excellence"

“Strive for excellence, not perfection, because we don't live in a perfect world.” is the full quote.​

 

[Richard Hed]

“Strive for excellence, not perfection, because we don't live in a perfect world.” is the full quote.​

Ah now, according to my wife I am perfect-- a perfect a**hole.

 

[timo_gross]

"Make it over, regardless of the time, effort and material needed.

It might work just fine, and might even WOW! those you show it to.

But you will always know it's not right.
And that's the only thing you'll see every time you look at it."

Couldn't have said it better myself.

If not too many of the matching parts that are attached have to be changed, a replacement part can be re-considered at a later time. This is my preferred way.
It gives me time to make my peace with the piece.
My inadequacy does not give enough room to make everything over (and over, and over .... ), regardless of the time, effort and material needed.
I do not think I can develop the patience and skills to get things "perfect", something will be always wrong.
Too often (a.k.a. usually) I end up with a "semi finished" stage.

I try to find a blance between "good enough" and "scrap".

Tweaking things to exhibition quality, is something I can not imagine to ever achieve.
Maybe (who knows) I will get there some time. (my only chance would be the help of the forum )
For now I try to keep the fun alive, learn new things all the time. Struggling with not starting a new project every time, a semi finished item is already a great achievement for me .


Greetings Timo

 

[clockworkcheval]

Designers who copy and adapt existing designs have for ages been the mainstay of manufacturing know-how in the design office. When you change an existing component using the original calque most of the times you keep all the adherent often well-proven information like tolerances, surface roughness, material choice and such. Of course thinking is good and the slide rule should be within reach. The many blessings that came with Computer Aided Anything in design office and workshop also came with one major set-back: a wizard's pupil who knows the trick-movements but not their exact meaning can in a very short time with CAD design a component that at first glance looks good but at closer inspection can hardly be manufactured.

 

[Steamchick]

I spent my design "life" pre-CAD. I was one of those who were employed to take 40 year old designs and re-create engines with more than double the performance... before the original designers retired. (SO lots of consultation on the original design ad strength calculations was possible!) Unfortunately, after I left (for a more permanent company) the business folded within a few years. So all my designs exist "as installed" but are now at their end of life.. and the technology is lost to the scrapyard.
The only "CAD" was the company main computer that took 15 minutes per calculation then timed-out! I was allowed 4 calculations per night.
C'est la vie!
K2

 

[ajoeiam]

My son and I have had this discussion a few times. He is a precision CNC machinist we agree that the level of perfection should be based on the function of the part, I cast and machine so my parts are never to the perfection level that he is used to. He has worked on things like the optics ball on the AH64 helicopter gun ships. He also brings up that some times the tolerance levels set by the engineers are not attainable with the machines unless they are machined in a progressive tool path without any reverses in direction.
Art b

Hmmmm - - - that's one of the 'problems' with engineering.
There is a huge difference in working/usable and built to the drawings.
(I'm not talking about sloppy junk - - - rather about unrealistic tolerancing!)
What is fascinating to me is that the early model jet engines were finished by skilled craftsmen.
It tool a lot of years of development to get to where it was possible to complete the same engine without needing those final touches.

(Also interesting is that the very highest level of machine tool manufacturers still use hand scraping.)

 

[Steamchick]

To get the tolerances of fit required in all modern engine manufacture and assembly plants there are many fits that are to tighter tolerances than can be manufactured. But because high speed gauging can measure the sizes so much more accurately than the manufacturing process, the sizes of certain features of parts are graded, then selectively assembled.
E.g. The pistons are graded for bore fit (as are the bores in the cylinder block), the piston pins (gudgeon pins) are graded as are the related bores in the piston, the pins, ring packs, circlips and pistons are graded to combined weight for balancing with con-rod mass on the crank, main and big-end shells are graded for block and crank, con-rod and big-end, lots of parts in the valve train are graded, etc...
In modelling, it is not uncommon to make more than the exact number of some parts, and fit or lap to fit according to manufactured size.
It is not the fault of the Design Engineer specifying an "un-makeable" tolerance, but rather the skill of "the maker" to achieve the tolerance so the performance of the engine is achieved. A challenge met by many modellers.
K2