Author Topic: broken hinge  (Read 9397 times)

richard

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broken hinge
« on: February 19, 2012, 03:04:25 PM »
dropped a repro victoria spatz/ Bruetsch hinge on the floor the other day and it snapped . ashamed to say i bought these about 7 years ago and still not used them ! anyhow they are the only parts i have ever had from Germany that were substandard, poorly cast , with fracture lines behind and made of a poor quality Mazac type metal .
anyhow the question : does anyone know who could recast me 4 pairs of these hinges ? thanks as always
outside of a dog a book is mans best friend. Inside of a dog it's too dark to read .Groucho Marx 1895-1977

richard

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Re: broken hinge
« Reply #1 on: February 19, 2012, 03:06:26 PM »
this is how the 2 part hinge is made up
outside of a dog a book is mans best friend. Inside of a dog it's too dark to read .Groucho Marx 1895-1977

Bob Purton

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Re: broken hinge
« Reply #2 on: February 19, 2012, 08:23:43 PM »
Lost wax or sand castings?

Big Al

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Re: broken hinge
« Reply #3 on: February 20, 2012, 08:45:40 AM »
Having watched Fred Dibnah I caught a bit where they visited one of the last time trained pattern makers up in your neck of the woods associated to a small foundry, possible the heritage but still economically active one in the Iron Bridge complex. He has the skills to judge the shrinkage and create the patterns in wood for casting of all sorts of metals and alloys. Struck me at the time that it would be handy to know more about this set up. I imagine costs would be high but once a pattern is created it can be replicated so the better the pattern the less finishing on the casting. So many bits could be reproduced if the will to finance was present.
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Barry

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Re: broken hinge
« Reply #4 on: February 20, 2012, 09:10:55 AM »
No need to make a wooden pattern these days.
Draw it up in 3D CAD and have an exact replica made as an SLA (Laser solidified liquid - stereolithography)  This can be your perfect Pattern.

I am in contact with a Lambretta man who draws (3D CAD - Solidworks) components and then has them cast - in England.
He is supplying me with one of the best cast Iron replacement barrels and cast aluminium head kits.
He also has cast aluminium manifolds.

If the numbers are right (still small volume) he can draw and manufacture parts.  One-offs are unlikely to be economical.

Interested?


Big Al

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Re: broken hinge
« Reply #5 on: February 20, 2012, 09:29:11 AM »
This is true but the shrinkage rate is the key element of the casting as the copy can be the wrong size or have wrong stress in it if incorrectly calculated. Is that why the hinge in question broken the first place? Copying an existing item is very much more difficult than making a new or replacement item. The percentage accuracy needs to be established. Some folks are very picky about parts. However go to far and they are more picky about the cost. All tricky stuff.

Meanwhile in the other part of the brain.
I like the idea of a guy making a thing with his hands, having the knowledge it is going to be correct and doing it. If computers do all these jobs then that skill dies out. Great until for some reason computers are not able to do the job or even the basic notion of what the process of the programme is doing is not passed on to the computer operator. There are so many instances where the human element no longer understands the function of the computer programme so the answer is meaningless to all till the result is found to be totally inaccurate. Its called progress but as far as I can see much progress has resulted in parping up simple tasks that a brain can cope with quite well enough with a bit of training rather than producing a race of talentless drones. Still perhaps they will suffer natural selection during the oncoming recession we are not having (having been missed by computers, or was the operators of the computers?).
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Jonathan Poll

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Re: broken hinge
« Reply #6 on: February 20, 2012, 09:53:57 AM »
dropped a repro victoria spatz/ Bruetsch hinge on the floor the other day and it snapped . ashamed to say i bought these about 7 years ago and still not used them ! anyhow they are the only parts i have ever had from Germany that were substandard, poorly cast , with fracture lines behind and made of a poor quality Mazac type metal .
anyhow the question : does anyone know who could recast me 4 pairs of these hinges ? thanks as always

I only heard about mazac last week, now I realise so many parts are made out of it!

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marcus

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Re: broken hinge
« Reply #7 on: February 21, 2012, 07:35:30 AM »
^ JP, Mazac /Zamac is an alloy which includes manganese aluminium and bronze, sometimes also known as monkey metal or pot metal, it casts well and accepts chrome reasonably well, so used extensively for castings but not all that tough.

I cannot help Dickie, but hope you get it sorted and let us know how you get on!
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Jonathan Poll

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Re: broken hinge
« Reply #8 on: February 21, 2012, 09:37:16 AM »
^ JP, Mazac /Zamac is an alloy which includes manganese aluminium and bronze, sometimes also known as monkey metal or pot metal, it casts well and accepts chrome reasonably well, so used extensively for castings but not all that tough.

I cannot help Dickie, but hope you get it sorted and let us know how you get on!

You forgot to say how crappy it was! It oxidyses a lot, making it veryv pitted and horrible chrome!
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Bob Purton

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Re: broken hinge
« Reply #9 on: February 21, 2012, 10:17:16 AM »
^ JP, Mazac /Zamac is an alloy which includes manganese aluminium and bronze, sometimes also known as monkey metal or pot metal, it casts well and accepts chrome reasonably well, so used extensively for castings but not all that tough.

I cannot help Dickie, but hope you get it sorted and let us know how you get on!

You forgot to say how crappy it was! It oxidyses a lot, making it veryv pitted and horrible chrome!


I agree!

Bob Purton

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Re: broken hinge
« Reply #10 on: February 21, 2012, 10:43:19 AM »
Dicke, the hinge doesn't look that complicated, If you fancied a challenge you could work one up from a block of ali. Time consuming but rewarding!

Jonathan Poll

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Re: broken hinge
« Reply #11 on: February 21, 2012, 01:37:15 PM »
Dicke, the hinge doesn't look that complicated, If you fancied a challenge you could work one up from a block of ali. Time consuming but rewarding!

But then you cant chrome it (unless it was ali originally?)

I'll have to try working with blocks of ali one day, that would be the best way to make a schmitt steering bar for my model etc!

I'm currently working on a 2cv model, since the glue gun packed up, cant work on the schmitt anymore, but 2cv only needs soldering!
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Bob Purton

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Re: broken hinge
« Reply #12 on: February 21, 2012, 04:46:35 PM »
Aluminium can be chromed. Have you not seen the MOC albert mirrors? The chrome peels off them like a tangerine but chrome plated they are! in fact recently I saw a platers advert showing how he chrome plated an apple!

Barry

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Re: broken hinge
« Reply #13 on: February 21, 2012, 06:04:21 PM »
This is true but the shrinkage rate is the key element of the casting as the copy can be the wrong size or have wrong stress in it if incorrectly calculated. Is that why the hinge in question broken the first place? Copying an existing item is very much more difficult than making a new or replacement item. The percentage accuracy needs to be established. Some folks are very picky about parts. However go to far and they are more picky about the cost. All tricky stuff.

Meanwhile in the other part of the brain.
I like the idea of a guy making a thing with his hands, having the knowledge it is going to be correct and doing it. If computers do all these jobs then that skill dies out. Great until for some reason computers are not able to do the job or even the basic notion of what the process of the programme is doing is not passed on to the computer operator. There are so many instances where the human element no longer understands the function of the computer programme so the answer is meaningless to all till the result is found to be totally inaccurate. Its called progress but as far as I can see much progress has resulted in parping up simple tasks that a brain can cope with quite well enough with a bit of training rather than producing a race of talentless drones. Still perhaps they will suffer natural selection during the oncoming recession we are not having (having been missed by computers, or was the operators of the computers?).

I am sorry but you really are living in the past Al.  The reason there are not any Pattern makers about is because they are no longer necessary.  Like so many trades, they are a thing of the past.  Any modern foundry will make patterns using 3D CAD' it is absolutely accurate.  You get exactly what you draw.  I started life as a draughtsman using ink on tracing paper.  Then came 2D CAD.  Then 3D CAD.  Then 3D solid modelling.  Should I be drawing with pen and ink now because it is a skill?  I am now deal with new product design, development test and introduction.  I deal with plastic mouldings, making mould tools using 3D Solid modelling, rapid prototypes - mould tools cut direct from CAD where the parts are almost perfect from the first trial and all the parts are to size and fit together.

If the hinge were drawn up in CAD a perfect hinge could be machined from solid.  Probably an almost economical way of producing a one-off (and easy to make another one or two exact copies as the CAD is always available).

Have an open mind to progress, it's not all bad.


marcus

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Re: broken hinge
« Reply #14 on: February 21, 2012, 08:06:39 PM »
Aluminium can be chromed. Have you not seen the MOC albert mirrors? The chrome peels off them like a tangerine but chrome plated they are! in fact recently I saw a platers advert showing how he chrome plated an apple!

Yup Aluminium can be chromed, it is just a question of who does it and how many intermediate stages they do, as well as the exact mix of metals. Very little is manufactured with pure ali, and different ali alloys hold chrome differently. The Premier Drum company was just famous for the exceptional quality of its chroming process and some ali snare drums of theirs are still immaculate 40 years after being made, although careful owners and dry storage help; Rolls Royce always kept quiet about having their chrome done by a drum company!
Just remember: as one door closes behind you, another slams in your face