New project, the second one!

[metalnwood]

Hi all, here is the thread for my second project. IAlthough at this point I am unsure of what it will be.

I am really quite enthusiastic at the moment, I have spent many months on my previous project that I was a bit tired, that and doing things for friends is all I have been doing in the workshop lately. After that my first engine was a breath of fresh air, not to mention something I have wanted to do for a long time.

If you saw my previous thread you would have seen me saying that I wanted to to a horizontal engine. After looking about it seemed like Elmers factory was probably the way to go but I have now changed my mind.

Since looking at the plans it is just too small for some of the parts I want to play with.. Also some of the fasteners are so small that I would need to go and buy more taps and material as I never work with things that small.. Thats just an issue for now, not in the future.

Now I know my choices will be a little bit more limited so I need to find something a little bit bigger. I have liked some beam engines I have seen, I liked the walking beam but I think I read that is from a book.. Books are not a goer at the moment because they are not sold in New Zealand and end up costing towards $100 by the time they eventually get here.

I also want to do this next one from spare stock as much as I can.

Living in a metric country I have silver steel on hand at 4, 5, 6, 8 mm diameters 0.157", 0.196" and 0.236". For my first engine I did buy a 1/2" reamer so building an engine with a 1/2" piston would be good although I don't mind jumping in size, the closet to 1" I have is 22mm or 0.866"

So, can anyone suggest something that would suit these slightly larger materials? I have spent a lot of time finding something but it does seem a lot of plans come from books. Checked all the libraries too, nothing there..

Thanks,
Jason

 

[GailInNM]

Jason, you might consider Elmers Grasshopper engine.
http://www.john-tom.com/ElmersEngines/37_grassHopper.pdf
It has a 1/2 inch bore and the materials could be varied quite a bit without any problem to suit what is on hand. It does have 2-56 screws, but I think there is enough metal everywhere that that they could be M3. Certainly enough for M2.5. It is quite open so things could be altered a bit for the larger screws.

What is the smallest screws you are comfortable with under your present circumstances?

Gail in NM

 

[Metal Butcher]

Jason, I find many of Elmer's plans (and others) a little small at times. There is a simple solution to this size problem, that I'm sure many of us face.

Its not at all difficult to up-size parts by 25%, 50%, 75%, or even 100%. and use whatever hardware size you deem appropriate. This will allow you to build projects you really like, rather than having to pass them up.

-MB

 

[metalnwood]

Hi Gail and MB, Gail, I guess the threads are not really the problem, I can turn 3mm on the lathe, anything smaller and my leasdscrew/gearbox combination doesn't support it. I could approximate the pitch with the feed bit that doesnt use the leadscrew so I am not sure how accurate it would be on really small threads although it work no problem on 4mm thread.

MB, I wasnt sure how scalable the engines are.. I know some things won't scale but I guess thats not really the case for engines as thats all these thing are really.. Of course I don't want to scale if I dont have to because I will introduce a few mistakes along the way because of it. Not the end of the world though..

I do think my lathe will be a problem with some parts. I put in some aluminium for a crankshaft 4" long and I am not sure I can do it I will need to go back and have a better look but the width of my toolpost may give me a problem on something that size when I need to do the right hand side..

Jason

 

[Metal Butcher]

Just to give you some ideas here is an up-scale I did last year. I made oter minor changes along with adding a reversing valve that I learned from build a previos model designed by Elmer.

http://www.homemodelenginemachinist.com/index.php?topic=4486.0

-MB

 

[metalnwood]

No posts from me for a few days. I decided to do a horizontal engine still but I am not sure about the plans.

I am going to make sure I understand the workings and draw something on the computer. This way I can scale and change a thing or two that may be difficult for me to make..

I will make sure I post for review as I am no expert here!.

Thanks,
Jason

 

[hammers-n-nails]

here is a couple vidieos of my first engine, its not much to look at(my fault), but it runs good even though the piston isnt lined up in the bore. i bought the plans for it along time ago but i cant remember where and the prints dont have a designer name or anything on them so i guess it would be alright if i scanned them and sent them to you.


[ame]http://www.youtube.com/watch?v=pTgyHnYgNBo[/ame]

[ame]http://www.youtube.com/watch?v=0wuRjfjlv7I[/ame]

 

[JohnS]

Here's another take on building a larger engine. In this case it was Elmer's #33. I had already built one to plan then decided to build a larger one by increasing all dimensions by 50%. I printed out the plans, enlarged them to A3, tipexed out all dimensions, photocopied to get a clean start and wrote in all measurements increasing by 50% and at the same time converting to metric which is my preferred route.

Out of all the engines I have built this is the most satisfying, it will run all day (and has done several times) on just a whiff of air. Those interested can see the result and compare the two sizes on my blog (scan down the page) at http://start-model-engineering.co.uk/about-the-author/my-engines/.

My current project, nearing completion is 'Opus Proximum' - a vertical engine designed by Stan Bray which is featured in a special issue of Model Engineer and again, I have increased all dimensions by 50%.

John S

 

[metalnwood]

Hi John, thanks for replying. 50% does make it seem a lot larger and starts to get to size I am happy with.

Did you also move to metric bolts, the closest size up?. I will go back to his plans and see that I think may be difficult for me at that size.

Thanks,
Jason

 

[JohnS]

Hi Jason

I much prefer working in metric because apart from anything else there is a greater choice of fastenings. I tend to keep to the smaller sizes (M2, 2.5 and 3) and, where appropriate increase the number of bolts. For example you may have noticed on my mill engines the steam chest and cover is held by just 4 bolts on the original version. For the bigger engine I used 6 bolts (studs and nuts to be accurate) and this I feel gives a more accurate scale appearance. Clearly you do need to check that adding or moving bolt hole positions doesn't compromise the workings of your engine. So by all means increase the size of your engine but don't automatically increase the size of fasteners.

Upping the size offers further scope to enhance appearance. Detail like split bearing mounts on the crankshaft and connecting rod can be added to enhance scale appearance. Again, in the authenticity stakes, I prefer the appearance of true to life studs and nuts rather than bolts. Also, studs Loctited into position avoids the perils of stripped threads which is all too easily done with say repeated screwing in and out of steel bolts into aluminium.

John S

 

[metalnwood]

Good point John, I didn't think about the look of the scale, being new to this hobby.

I was lucky today and sold a few things so I can buy a few extras and maybe do it out of some nice metal.. Hopefully the family will give me some time on the weekend to redraw the plans.

thanks,
Jason

 

[metalnwood]

I started to sketch up the components, it doesnt take all that long when you consider how long it takes to make them. 10 Minutes spent on a connecting rod doesnt seem that much when I will spend a lot longer machining one.

I couldnt help myself, I had to put the pieces I have done so far together and see them run
[ame=http://www.youtube.com/watch?v=dyt40uTRpLI]http://www.youtube.com/watch?v=dyt40uTRpLI[/ame]

 

[zeeprogrammer]

Jason...I don't know anything about modeling on the computer...what did you use? Is that 'Assem3.avi' a clue?

John S...nice tip on scaling up. It probably would have taken me a while to think that scaling up can mean 'more' not just 'larger'.