Hello and it's time to build something

[Basil]

Hi Everyone. I live in Poole, Dorset and have done for the past 7 years, Prior to that I lived in the US for 35 years. Mechanical engineering is what I have always done. Approaching retirement now and have taken on a build from Hemmingway of the Seal Major 30cc which I plan to run in a model boat. A passion of mine from a very early age. Also into 3D resin printing CAD and messing with big boats. I will ask a question here but please advise if it should be posted under a different category. Do I need to Age the castings I receive in a kit like you would say for 356 ?. I have a heat treat oven. Is it recommended anyway. Unfortunately I have done some machining already on a few faces. Thank you and I hope everyone is well. Cheers

 

[goldstar31]

I am NOT an engine er but there are plenty of professional practices to go on.
In 1944- when I was 14, my friend at the time was employed at a Tyneside firm as a beinning of his apprenticeship to 'rough machine' castings and to leave them to weather or normalise- before final machining. Long time ago, it is true but my father who had apprenticed as a blacksmith/farrier in Consett Iron Company asserted that cast iron was 'porous'. Certainly, it distorted and I'd hate to count the number of times that I found distortion on full size A series engines - from BMC Longbridhe.
Moving onto I recently reported tht I built a mill drill to Westbury's design and the headstock on splitting 'nipped up'. This required laborious scrapping. I'd worked to too close a rolerance.
It then became time for the late George Thoomas to publish amongst many other things, the Universal Pillar Tool-- and the then split 'arms'( they would be vconrods in another world- nipped or closed up.
When I came to make mine from castings by Hemingway, the Mark2 arms were available. These held on the vertical pillar with one poece collets. Thomas's friend and encourager was Professor Dennis Chaddock who remarked on this because his Quorn had a choice of single split bores or single one piece collets.
Having a UPT, I went for the single collets and I have the Quorn still.
However, I also have a Kennet tool and cutter grinder- which is donkey's years old and has much the same 1" diameter cartridge spindle as the Quorn and the Stent. It is held in place with two clamps- and after all these years- clamped up.
You will, if you wish, note my comments about a Britannia close out of Oz. I was getting into hot water- but I opened the bore of the Kennet- with nothing more than a neatly inserted screwdriver blade.
Yes I did panel beating in my retirement. I know how and where to hit.
So that is my story as briefly as I dare

Norman

 

[Cogsy]

Your castings should be good to go without any ageing. I got some a couple of years back (different source and different engine but still applicable) that were rushed to me straight from the foundry and never had an issue. I've also cast the odd piece myself in the backyard and sometimes gone from casting to machining on the same day. If they seem to be machining well then I'd say go for it.

 

[BaronJ]

Hi Basil, Guys,

The general problem with castings, depending upon size, is the amount of time they take to cool, particularly cast iron. As they cool they change shape in various ways.

For small castings just a few pounds I would say not, they are unlikely to move now. The real issue is when machined stresses may be relieved that cause twisting. Steel will do the same unless you use stress proof !

Many years ago I used to furnace weld marine engine castings that has cracked in some place or other. Firebrick igloos were built around them and heated with gas burners to get the cast iron red hot. Some of these igloos were over ten feet high ! They could take a fortnight to get hot enough to weld and at least as long to cool to a temperature to handle them. A couple also cracked somewhere else as they cooled.

Fortunately someone came up with the idea of metal stitching ! A much nicer process.

 

[ajoeiam]

Hi Basil, Guys,

The general problem with castings, depending upon size, is the amount of time they take to cool, particularly cast iron. As they cool they change shape in various ways.

For small castings just a few pounds I would say not, they are unlikely to move now. The real issue is when machined stresses may be relieved that cause twisting. Steel will do the same unless you use stress proof !

Many years ago I used to furnace weld marine engine castings that has cracked in some place or other. Firebrick igloos were built around them and heated with gas burners to get the cast iron red hot. Some of these igloos were over ten feet high ! They could take a fortnight to get hot enough to weld and at least as long to cool to a temperature to handle them. A couple also cracked somewhere else as they cooled.

Fortunately someone came up with the idea of metal stitching ! A much nicer process.

Curious - - - - would you please explain or describe 'metal stiching'?

 

[BaronJ]

Curious - - - - would you please explain or describe 'metal stiching'?

Metal Stitching is exactly that ! A method of joining two pieces of metal together. In the context that I was referring to where you have a crack in an engine block made from cast iron and the only way to repair that crack was to heat the casting up so that the crack could be welded up.

The crack could be stitched together and a permanent repair made by drilling a series of holes on either side of the crack and hammering a steel bridge across the crack into the drilled holes.

The holes were drilled using a template and sometimes a coned drill creating a slightly tapered hole. Then hammering in a bridge which caused the two edges of the crack to be pulled towards each other.

After hammering in the stitches, this is what the steel bridges were called, they would be welded or brazed to the casting to prevent any further movement.

You can get stitches in varying sizes from small 1/4" inch ones right upto whopping great 1.5" inch ones that needed a sledge hammer to seat them properly.

Very soon after stitching was introduced I was made redundant as my furnace welding skill was no longer required. In fact its only in the past few years that I've thrown the certificates away as just junk.
As far as I'm aware no one does this sort of welding work any more.

 

[L98fiero]

Curious - - - - would you please explain or describe 'metal stiching'?

The basic idea is that there are a series of overlapping tapped holes running the length of a crack. The threads seem to be a Dardelet thread or some variation of that and an inverted conical shoulder under the head of the fastener like on clinch nuts, the combination produces a radial load holding the crack together. Here's an image of the fastener that a company called Lock-n-Stitch uses though I've also seen it done with just plain brass screws that were peened over and filed smooth after being locked in place on an engine block of a farm tractor, a early sixties farmer fix.
PS, After seeing Baronj's post it's obvious there are couple of variations of the idea, this is what I've seen.
PPS, It would be interesting seeing how they cut the threads of the fasteners!

 

[grahamgollar]

Baron is obviously referring to the Metalock method of cold stitching as seen in the following: Metalocking Metal Stitching | Metal Stitching Cast Iron He shouldn't have thrown his certs away though because we still use welded repairs on large marine engine cylinder covers (heads) where the complexity of the casting shapes would not suit the Metalock process. Also, the extreme thermal and pressure variations could cause the combs to be released with serious results!

 

[BaronJ]

Baron is obviously referring to the Metalock method of cold stitching as seen in the following: Metalocking Metal Stitching | Metal Stitching Cast Iron He shouldn't have thrown his certs away though because we still use welded repairs on large marine engine cylinder covers (heads) where the complexity of the casting shapes would not suit the Metalock process. Also, the extreme thermal and pressure variations could cause the combs to be released with serious results!

Hi Graham,

Thank you, I couldn't remember the name. Yes "Metalock"

Their training guys came and spent a couple of days with the firm I was with, my boss and mentor was an old guy that had been doing furnace welding for about 20 odd years or so. It was him that got me into a collage to learn how to both gas and electric weld and where some of the certificates were issued. I also went to BOC for safety and gas training.

I don't regret throwing that stuff away, at my age I'm never going to need them ! Anyway it was hard physically demanding work, I wouldn't want to do it again.

 

[L98fiero]

The threads seem to be a Dardelet thread

View attachment 120284

I've done some investigation since posting this and the type of thread is wrong, for some reason I remember seeing this thread somewhere and connected the Dardelet name to it but that isn't what it is, does anyone know? The Dardelet is a kind of self-locking Acme but this is more like a buttress but with a negative angle on one side.
According to Lock-n-Stitch, "We invented a new thread form in 1993 and began selling it in 1995. The thread is called Spiralhook ™. It utilizes a special shape that includes a negative 20⁰ hook angle on the upper side of the thread teeth that revolutionized the capability of metal stitching and threaded bolt hole repairs." but I've seen drawings of similar threads long ago.

 

[BaronJ]

Hi Guys,

I've not seen that technique before, and whilst I can understand how it works I don't know if it would be suitable for closing a crack in a casting.

 

[L98fiero]

I've not seen that technique before, and whilst I can understand how it works I don't know if it would be suitable for closing a crack in a casting.

The fasteners shown wouldn't work as well for a casting that's broken in two, these are more intended for repairing a crack. The old school way I saw it done with just plain brass screws was done on the deck of an engine that had frozen and cracked the casting and that did work as intended, the fasteners I showed are intended for that application. I have no interest in promoting Lock-n-Stitch, I've never used it but I've seen the old school method and know it works and expect the new method would be better. FWIW, Lock-n-Stitch does also have the 'bridging' type of crack repair and is a division of Wärtsilä, they seem to think it's an acceptable method.

 

[clydeman]

Lock and Stich is what I have used on the farm over the loast 30 or 40 years
http://www.locknstitch.com/index.html

 

[goldstar31]

Lock and Stich is what I have used on the farm over the loast 30 or 40 years
http://www.locknstitch.com/index.html

I was taught to use a nd sewing machine from the age of 3 or 4 by stitching together old newspapers-- and sort of went om from there.
I made tents for myself and for the Boy Scouts, made canvas kayaks, made sails for sailing dinghies and rucsacs - and even duvet covers. Now, my eyesight is so poor that I c`annot even thread a needle.
I made heddles for weaving- and well, a lot of things.
Farms- well- my living room is called a 'a GinGang' because I sort of live on what is still know n as a farm-- from AngloSaxon times. My father was a blacksmith farrier who could fashion a horse shoe from a billet on ONE heat of the furnace.
I was simply a child who learned to exist and then profit in a World War.