Standard and Cylinder Castings and Molds.

[D&J Fitzgerald]

hi outthere, first i thank you kindly for members help , i am new never built a steam anything, the closest i have come to building a steam engine is in watching other peoples progress in youtube. I have never run a lathe in my life, my only experience is in model ship building, and in having decades of scratch building ships off of plans, has helped me in some very very light understanding in viewing steam engine plans, i see i have a long way to go, i do not have a degree in engineering at all of any kind but the will to conquer metal is at hand. i have a cheap chinese metal lathe 7×14 550 watt motor i am making progress and reading everyday all i can. i have several plan sets downloaded into my phone my faverate is a condencing engine
with Lp and Hp cylinders it is big 3 inch bore on one and a 2 1/4 inch bore on the other its 8 inches long, 7 inches tall and i think 5 inches wide a bit big for my 8 ft tug, i am going to follow the advice of the members and attempt a small single vertical with 1 1/4 inch bore. but i have a problem it requires castings, i would make the molds for the bed, and cylinder ,steam Chest and standard and i have the dimentions the standard is 4 inches tall showing two sides of its four faces one with the legs and dimentions the other side with the rectangle hole at the top of the standard but i am trying to figure out how i apply those two dimentional drawings of the standard to the the mold. i cannot find a book that covers completely on how to apply the drawing and dimentions to a wood plug , i will assume that the mold has to milled on my lathe slightly over size to leave material for machining. its just the standard. another sort of question is this does the Standard, Cylinder, Flywheel and base molds have to split in half for the mold box and the mold box split into two as the case with the molds for the parts ? can someone confirm these things please. and maybe this is stupid question but, i asume i have to mill the molds to dimentions indicated plus extra for milling on my lathe correct?

plus mentioning the size of the first engine thatbi wish to build as i get more experience is my 7 by 14 big enough to build that engine maybe not. i am ordering the ray hasbrook book soon.
the vertical steam engjne will be my first go, i have decided this, i got the plans from i think Tom.com the plans are easy to understand and the dimentions its just the plans, to mold, to castings problem. could I machine the standard out of wood and omit the legs to make it simpler and add the wooden legs later? again must all the molds be in two parts for the casting sand boxes. please kindly someone answer these issues.
thanks very kindly Dan.

 

[abby]

Hello Dan ,
Some of your post requires several reads to understand but basically what you are refering to as "molds" are actually called patterns.
depending upon the metal that the castings are to be made from the patterns must have an allowance over the finished part dimensions.
This allowance (general rule of thumb +2.5%) is to allow for the shrinkage that the casting will have.
The patterns can be made from whatever material you like and by any method you like but if wooden they should have a good coat of paint to protect from moisture pick-up.
Split (on the halfline) patterns are convenient for greensand moulding but not entirely necessary , google "odd-side" moulding.
The type of pattern will be governed by the quantity of castings required , a split pattern is quicker to mould than a whole pattern , in commercial terms quicker equals cheaper.
The split pattern is easier to remove from the sand without damage to the latter.
A 7 x 14 lathe ? I guess is what we in the UK refer to as a 31/2" lathe such as a Myford ML7 and I would say that someone with experience could machine most of your chosen engine on a lathe of that size although some parts eg. flywheel might need subbing out , unless your lathe is a gap-bed of course.
The whole process of moulding and casting does require some experience and knowledge to get good results.
The feeding of a heavy casting is critical if shrinkage defects are to be avoided , you might also google the use of "chaplets" and "shrinks"
These are pieces of metal strategically placed within a green-sand mould to promote faster cooling in areas where shrinkage has caused a depression in the casting.
I hope this has covered some of the questions you asked.
regards
Dan.

 

[D&J Fitzgerald]

Hello there, Thank you kindly, all whom contributed in helping me out.

My interest in casting parts, relates to my interest in building a number of single vertical steam engines, all are indeed , not one off, ideals accept where ,applicable to my model ships requirements. In regard to the patterns ( thanks for the terminology correction) I no problem producing the patterns as I no more about casting then I do about lathing, the plus in making patterns for castings, is that I can learn to make precise parts out of wood, any errors in cutting and crafting the parts can be thrown away and retried, in doing so, I will learn how to properly measure and cut the required items for castings, I could of course a one off unit of Rays designs a double or triple for my tug then start the castings project for the singles I wish to build, but I feel that knowing exactly how to construct properly the parts in wood first is the best way of averting disaster on my first real engine build attempt. It is time consuming and somewhat of a waste to some, but to me metal is precious and I do want to waste on learning curves that me a successfull build.

My tooling that was stolen still appears not to be forthcoming from the person that took it, so I must decide whether to accept the loss, and replace all, if so, this will set back my schedule on start up. As I must buy, a vertical milling attachment and a independent four jaw chuck cutting tools,measurement tooling, metals, and also I will need a brazing welder, a grinder a 1/2 inch Jacobs check for the tailstock, I do require also a steady rest as prop shafts for my boats will milled, I need also taps and dies and also I must learn how to make brass reduction gears for my models and the kit I am going to produce for kids.

My lathe is that one on eBay it's blue and white the utter cheaper one from China, I have only ran it once the tail stock, saddle and motor ,gearing speed control reverse and so on all work well but the motor was not bolted into place so I have to fix this also. It is a good lathe as far as I can detect, I do wonder though why they even small ones are so Heavy. In any event my wife and I are in agreement to move forward with the investment. A milling machine would nice, but according to old old arrivals I have, the ones you spoke of, back in those days, I see that most steam model engines were built with basic lathe and drill press no milling machines in some cases . I must learn how to place a cutting bit into the tool holder, that should give you all an idea of my experience with this great tool I now have, and I evethough the lathe came with a unbolted motor, am thank full to have one. Must go, thank all for your experienced advice which I will adopt into practice .
Dan.

 

[Jasonb]

Given that castings are generally harder to hold than barstock and you only have a 4" 4-jaw and hope to get a vertical slide I would say you will not gain much if any time by going down the casting route for a run of 4 engines. For a start with no machining experience you should get at least 5 sets cast in case of muck ups and castings are not cheap to have done so any thoughts of recovering costs are not really going to happen. Also you are only going to get a decent price if you can sell on decent quality engines, I think most of us will admit that our first efforts were not the best so bear that in mind too.

How much do you know about casting, you have already said you find it difficult to understand the 2D drawing and they only detail the machined surfaces you will have to work out the size, thickness etc of cast surfaces for yourself. Do you know about draft angle, cores, core boxes etc?

The usual negative comment about far eastern lathes is that they are off too LIGHT a construction and that the old heavy cast iron were far better as they were more rigid. I don't think I have ever heard anyone say that the castings and construction are too heavy on mini-lathes before. If you still have to fix the unbolted motor I do wonder how you managed to check that it ran OK?

 

[D&J Fitzgerald]

To Jason, well Jason, I appreciate your response, although critical!
If you had read what I had said then you would have learned that my reference regarding the two D drawings was regarding the standard. Regarding my lathe it is very heavy, I can hardly lift around and regarding the motor being unbolted, yes I did run the motor, the motor is so heavy that I wedged it it
In place after I placed the toothed belt on the cog, then I tested my lathe.

Regarding my abilities Jason all I can say is that my dad had a PhD in engineering my father-in-law has a Ba in engineering as well from Canada's famous UBC,I do not, but because of family gene pool I guess I am smarter and pick up on things fairly quickly I have been blessed with a photographic memory. You see you place the parts on the table, then you create a solution as my friends at NASA would say. These family do not make me a engineer, but I will say Jason that I am smarter then some people in some respects and not in other respects. I do not mind casting parts my problem is a Crucible, I cannot light one up here, further I have found a reasonably priced milling machine which I am considering saving for. I do not foresee an issue with my builds, accept that on the side of caution , it's best to perfect my milling on wood as opposed to metal,in so doing, it's best to not waste the wood and creat the castings patterns ,IAM going to build one of rays doubles, and actually based upon my read on several sets of plans, my understanding of them is 75 percent, it's simply going from the plans to lathe and creating on the lathe with key measuring instruments that is all. And for things IAM not sure of, I ask for help from like minded people, some of advice I will use some I will not.

Regarding a milling attachment as I said I have a milling machine that's not to pricy,I may buy it I may not I have nothing against bar stock engines, and it's probably just as fast as casting or faster, I have casted parts in past for my model ships so I will probably try again. I want to take my time and learn from other people's mistakes so that I can avoid making the same mistakes. We are only human Jason and we all make mistakes, your engine building stands out great work you have done, and I appreciate your advice.
Regards
Daniel7.