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NickG's Mine Engine

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NickG:
Hi All,

Just thought I'd post some of the work I've done in the new year, unfortunately so far it's only in the 'virtual world' of CAD!

I've been studying and mulling over lots of drawings and my list of ME projects has changed and changed back many times.

I've been thinking about buying castings, then thought about doing one of Elmers engines from bar stock, then I considered doing my own design of a Corliss, then a beam engine from some French plans, then doing one of Stews engines as I know they look and run really well.

You get the picture, some might say this is just an excuse for not getting in the shop and getting on with something!  :slap: However, I think it's because there's either some machining process in there that I'm uncomfortable doing and the engineer in me thinks I could make that easier for me to make and maybe suit materials / sizes I know I have.

Anyway, at some point (not sure why) I settled on designing my own Mine or Table Engine. Anybody who has used CAD will know it's fairly easy to come up with beautiful works of art that are extremely difficult to make, so I try to design my components with manufacture in mind, using methods I know I can do. Try to reduce the number of components, no or little fabrication, standardise components and sizes. Unfortunately I picked an engine that has quite a few components! I also get a bit bored sometimes when embarking on a large project so I tend to design simple components. I've tried though to put a few frills on here and there but nothing complicated!

Before Jo starts talking about studs  :naughty:, the chances are (if I can be bothered) the steam chest and top cover will have studs and nuts rather than bolts - I just haven't got around to modelling them yet.

I've got enough 8ba nuts / washers but I think they might have 9ba heads and look too small here - is this normal? I think the 8ba bolts I got had 9ba heads too  :shrug:

Still quite a few parts to model yet, then all the working drawings to create so it could be a few weeks before I cut metal on this.

To give an idea of scale, the flywheel is 4" which it is largely based around  - I thought I'd use the RDG casting the wife got me for xmas, then I can't be accused of just leaving her xmas present on the shelf for years!

The cylinder is only 5/8" bore and 1.25" stroke despite looking like it should be bigger, this is due to the method of manufacture I've chosen.

One thing I've been struggling to make a decision on is the valve linkages  :-\. I've got an idea which I think I'll get cracking on as my sheet of A4 with scribbles on looks just like that now  :facepalm: Need to get them modelled to see if they fit with the rest of the design.

Any comments / improvements / criticism welcome!

Here is the progress so far:

NickG:
One thing to ask already is, if I do use studs, how do people go about it? I thought 3/32 rod would be about the right size for 8ba - but I would need to open up the clearance holes a bit. If I used 3/32 rod, would I cut the threads straight onto the end or would it need turning down by 7 thou on each end prior to threading?

Or, for this, seeing as there will only be about 14 studs, could I simply buy 8ba studding - I know it's not as good etc but for this it would give the desired effect?

Thanks,

Nick

Jo:
Nick,

When you make studs don't use anything less than 1/8" it flexes too much, then turn it down 8). Looking at the size of your model I would opt for 10BA studs & nuts not 8BA with 9BA nuts. You will struggle to get spanners and nut runners the right size. 10BA is 3mm ish (2.97mm) so you can get then anywhere.

Depending on the lengths you are talking about having the plain piece in the centre may be too much like hard work (I gave up on my 12BA studs :ShakeHead:)

Jo

stevehuckss396:

--- Quote from: NickG on January 20, 2013, 09:41:12 am ---One thing to ask already is, if I do use studs, how do people go about it? I thought 3/32 rod would be about the right size for 8ba - but I would need to open up the clearance holes a bit. If I used 3/32 rod, would I cut the threads straight onto the end or would it need turning down by 7 thou on each end prior to threading?

Or, for this, seeing as there will only be about 14 studs, could I simply buy 8ba studding - I know it's not as good etc but for this it would give the desired effect?

Thanks,

Nick

--- End quote ---

The correct rod is available. If it's worth it to you you can get it.

http://www.ba-bolts.co.uk/threadedbar.html


8 BA is almost exactly the same size as #2-56. That is also available in rod for sure because I have a foot or so out in the shop. The 2 are so close I doubt anybody could tell.

NickG:
Hi Jo, thanks for that, so you turn all yours down from 1/8th? argh! this stud business sounds harder than i thought! thats why i thought could you just put 8ba straight onto the 3/32 rod without touching in lathe? its 7 thou oversize but guess thats quite a lot when talking about this scale. when I put 10ba on, it looked too small to me.  The size ive drawn us 8ba but when ive looked at the 9ba headed ones i on my smaller models i think they look too small fir this (by my standards) larger one. I was debating whether to use 6ba! The spanners arent a prob, my grandad left me a box of them that have 0-12 and 0-10 in box spanners! 10 maybe more realistic scale wise if that's what you mean? There prob should be a lot more than 6 too I guess? I don't like tapping that small though, let alone 12ba! Using 10 there would mean I couldn't use any smaller elsewhere on the model.

Thanks for the link Steve will have a look. I don't have any taps / dies the sizes you mentioned but I do have a set if small metric ones so will look into that too.

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