Author Topic: Jason's " Rogue " casting thread.  (Read 5716 times)

Offline ImIndoors

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Re: Jason's " Rogue " casting thread.
« Reply #15 on: March 02, 2016, 02:55:27 PM »
My experience of castings is not extensive and I am not a fan so thanks to contributors to this thread for valuable insight.
Regarding hard spots: I once bought a chunk of round cast iron bar to make a small flywheel and found a hard spot about the size of a grape deep within it.  I was using a carbide tipped tool and I could hear and feel the hard bit before it became apparent to sight by it's shiny appearance.  The solution was to put the workpiece in the bottom of my coal fire in the evening (after taking it out of the lathe  ;D) and leave it there till the fire went cold the following day.  The hard spot was still there but much reduced and easily worked.
Jim
The person who never made a mistake never made anything.

Offline Alyn Foundry

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Re: Jason's " Rogue " casting thread.
« Reply #16 on: March 02, 2016, 06:14:19 PM »
Graham

If you some more from the past  :
Note this is from when I was 16 now 69

My uncle was a brass mouldier that's where the willow wand info came from they used Coke fired hole in the ground crucible boy you had to be tough to pull them out

Another uncle used to do CI moulds built up with bricks covered in the afor mentioned material and struck off with a strickel /sp these were for large slag ladles and siphons used in the old town gas pipe work

So not done it but seen a lot done

Have you come across the old timers not wanting the sunlight to shine in the foundry because they judged the temp by colour , they would not tolerate the pyrometers

Now a bit for the steam buffs , the pipe pit crane was a king post crane hydraulic powered , fluid used cannel water the pumps were triple units ( not expansion jobs but three proper HP cylinder ones) with very large acumilators spread around the works

Boy that's made me feel old

Stuart

Hello Stuart.

Well I'm only 10 years behind you!!

Ah, the dark foundry floor.... Yes indeed a trained eye could see the temperature, another reason, the " pisser " a lovely foundry term for a leaking flask.  :)   Much easier to spot in low light.

The foundry at Rhuddlan had been around for nearly 150 years, formerly Corbett Williams agricultural equipment and engines. They had a pit in one corner but in all the time I dealt with them I never saw it used.

Both Rhuddlan and Buckley foundry used the " Green sand moulding " method but Buckley also had a huge " Shell " moulding system as well. Rhuddlan used a 3 Ton per hour Cupola whilst Buckley had modern induction furnaces. The sand was the common denominator, a lovely dark red with very fine grain texture, the " Virgin " sand was a mix of sand Bentonite and Coal dust and of course water to bind.
This was used to just cover the pattern and then " backed out " with used, tempered sand. "Tempered " is the term used for the water application of around 4/5% moisture.

A good finish to a casting is down to many factors but the choice of sand is the most important. I'm still using the same sand I bought nearly 30 years ago. My sand was just Mansfield Red with a touch of Bentonite, no Coal dust as it stains Aluminium.

Attached is an example of a casting I did a couple of years ago, virtually zero fettling!!   ;)

Kind regards, Graham.

Offline Jasonb

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Re: Jason's " Rogue " casting thread.
« Reply #17 on: March 05, 2016, 08:50:56 PM »
Mound Misalignment

This is where one half of a casting does not line up too well with the other.

This aircooled cylinder is a good example

As you can see along teh part line the two sides of teh fins do not line up, the fact one half of the bottom has cleaned up and the tool is still not touching the other side also shows how much they are out of line.



A good seeing to with an angle grinder removed some of the high spots



The low spots were filled with JBWeld and once rubbed down and painted who would know




This bronze casting is another example, trying to get the best layout of 4 holes had the large one slightly off which did not help to start with



Looking from the side you can see that the boss does not line up either side of teh part line



Which means that when the hole breaks out teh other side it is rather off :(



The cure for this one was to turn away most of the boss on teh back leaving a thin "sleeve" then silver solder on a "tube" once its had a bit of draft angle turned onto it and all been blended in only the different colour of the metal gives it away




Offline Alyn Foundry

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Re: Jason's " Rogue " casting thread.
« Reply #18 on: March 06, 2016, 03:31:07 PM »
Hello Jason.

I don't have a lot to say about mould misalignment. IMO there's only one guilty party, the supplier !! I rejected any castings that weren't up to scratch, the foundry soon learned the hard way that faulty castings don't sell.

Strong words, yes, but true.

I have attached a photo of the " Full " plate pattern of our ill fated Hornsby Akroyd engine. You will note the four " Slip blanks " which aid correct registration of the two flask halves. You might also notice, at either end of the pattern the tapped holes for the addition of guide runners. These guides align the plate to the flask box pins.

Our " loose, odd side " patterns were always fitted with patternmakers pegs so any misalignment in a casting was down to the moulder and not the pattern.

Kind regards, Graham.

Offline Mathew28

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Re: Jason's " Rogue " casting thread.
« Reply #19 on: March 06, 2016, 05:14:04 PM »
Hello Jason.

I don't have a lot to say about mould misalignment. IMO there's only one guilty party, the supplier !! I rejected any castings that weren't up to scratch, the foundry soon learned the hard way that faulty castings don't sell.

Strong words, yes, but true.

I have attached a photo of the " Full " plate pattern of our ill fated Hornsby Akroyd engine. You will note the four " Slip blanks " which aid correct registration of the two flask halves. You might also notice, at either end of the pattern the tapped holes for the addition of guide runners. These guides align the plate to the flask box pins.

Our " loose, odd side " patterns were always fitted with patternmakers pegs so any misalignment in a casting was down to the moulder and not the pattern.

Kind regards, Graham.

It's a shame there's not a like button on here Graham.
Never send anything out wrong! No matter how small it may be you're paying for a service!
Nil Carborundum illegitimi

Offline Jasonb

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Re: Jason's " Rogue " casting thread.
« Reply #20 on: March 06, 2016, 07:55:54 PM »
Mis-matched parts

I suppose this one is down to the pattern maker and is where one casting does not match the one that it is meant to join onto.

Take these bearing caps which are far larger than the bottom half of teh bearing cap they are meant to mate with particularly on the left hand side.



This is where the "cast" surface has to be machined of seriously fettled with die grinder, Dremel and or files to make things look like they should.



Here is another example on the full size these two parts would have been one casting but to make it easier for us to machine and the supplier to cast the model comes as two parts, unfortunately teh diameter of teh cylinder is about 3/16" smaller than the diameter of the surface it is meant to join with. A bit of freehand milling got rid of most of te offending metal before grinding and filing.



J

Offline Jasonb

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Re: Jason's " Rogue " casting thread.
« Reply #21 on: March 06, 2016, 07:59:32 PM »
Over Fettled parts

The eagle eyed will have also spotted in the last photo where the foundry man got a bit carried away removing the feed sprue and ground down below the surface of the part



The only way round this with iron is to get out the body filler



And give it a good rub down



J

Offline zeeprogrammer

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Re: Jason's " Rogue " casting thread.
« Reply #22 on: March 06, 2016, 08:01:25 PM »
Very educational thread.
Learning about the issues one can run into with castings and, more importantly, how to get around them.

Thanks!  :ThumbsUp:
Carl (aka Zee) Will sometimes respond to 'hey' but never 'hey you', whistles, and certain dinner bells.
"Found a peanut."
To work. To work. Zee-The Thread Trasher.

Offline Jasonb

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Re: Jason's " Rogue " casting thread.
« Reply #23 on: March 06, 2016, 08:05:29 PM »
Good to see you are finding it useful and seeing how to get round these issues and that its not putting you off using castings in the future.

I know of someone who has just let the moths loose on a casting set with a couple of faults, maybe they would like to show them  :stickpoke:

Online Jo

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Re: Jason's " Rogue " casting thread.
« Reply #24 on: March 06, 2016, 08:22:35 PM »
 ::) I think someone is just looking for evidence that I have actually got them.

The first is the inside of the skirt on a piston casting, which has cracked  :headscratch:

The next looks to be a flow problem but as it is magnesium I am not sure why.

The last is a reject crankcase, which was rejected due to the metal not flowing to the front of he case but I am planning on making the mounting a little shorter.

Jo

P.S. Those very desirable castings are hidden in a safe place  ;D
Usus est optimum magister

Offline airmodel

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Re: Jason's " Rogue " casting thread.
« Reply #25 on: March 07, 2016, 04:09:03 AM »
In the early days (30years ago) my castings had all those faults and more.

 Nowadays it is a trouble free process having learnt from my mistakes in the past.

Having said that I would be very angry having paid for those castings only to find all those faults when machining them.

Offline smfr

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Re: Jason's " Rogue " casting thread.
« Reply #26 on: March 07, 2016, 06:36:14 AM »
How about this for a bad casting  :o



That's a vintage Stuart Twin Launch cylinder block from the 1970s, back when they were supposed to be good!

Those voids go almost to the bottom of the casting. I've got email out to Stuart to see if they'll replace it  :ROFL:

Simon

Offline Stuart

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Re: Jason's " Rogue " casting thread.
« Reply #27 on: March 07, 2016, 07:47:01 AM »
Simon

I await your post on the result of the email to my name sake's

Stuart
My aim is for a accurate part with a good finish

Offline Alyn Foundry

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Re: Jason's " Rogue " casting thread.
« Reply #28 on: March 07, 2016, 11:57:55 AM »
Good morning All.

I fear this thread might put off model engineers from ever buying castings again !! Let's hope not.

Jason's first picture of a casting being oversized, unforgivable, that should have been addressed at prototype stage.

When I started on the Hornsby Akroyd who's bed and cylinder, like Jason's example were cast as one, I had the same dilemma. How to join the two parts together? My solution was to add a little extra onto  the water jacket pattern and machine a socket into the bed casting. The fillet was made part of the water jacket pattern and once machined blended near perfectly. A little extra thought made a big difference.

Jo.

Your pictures.

 A failed " drop test " ?   :)

The second one is more difficult with just the single view. But, could have been caused by " core crush " If the core was slightly oversized to the " print " as the boxes are closed the much harder core moves the sand, breaking it and the metal follows the new contours.

You final shot, many reasons, metal to cold, a short pour and even poorly vented mould will cause the problem.

Simon' picture.

Looks like classic " core blow " to me.

I'm pleased to read that our member " airmodel " has, due to years of practice honed his skills in this area of expertise, it dose take time!! I too can still remember all the " wasters " !!

Kind regards, Graham.

Offline Jasonb

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Re: Jason's " Rogue " casting thread.
« Reply #29 on: March 07, 2016, 12:38:29 PM »
Sand Inclusions

This is the cylinder of a model I must have started about 25-30yrs ago when I was a beginner and one of the reasons I did not finish it. Most of the gun metal castings had small pockets of sand within them which would take the edge off HSS tools as soon as one of the pockets was uncovered. This made boring very difficult as you would be half way down the cylinder and suddenly the note of the tool changes as it stops cutting and starts rubbing so retract tool, dig out the sand and try another cut with a resharpened tool OK until more sand is uncovered.






At the time it was beyond me to fully correct this, now I would probably have taken it out a bit larger with carbide tooling and fitted a sleeve or just scratch build a new cylinder.