Its a steam engine... Vaguely based on the PM Research #1

[Josh-MMS]

So, this'll be my second build. I thought it best to document it some other place than Instagram this time.

I'll apologise in advance for my sheer lack of steam engine vernacular, I'll almost certainly get some terminology wrong at some point.

I've been watching Joe Pie build the PM Research #1 on Youtube and got the bug to do another engine. I'm a big fan of the casting kits but for me they're a little pricey and I cant find anything in metric, so I'll stick with designing my own.

For reference, this is my first engine, a little double acting wobbler: <a href="https://www.youtube.com/watch?v=E1kaCuuhRaM" target="_blank">http://www.youtube.com/watch?v=E1kaCuuhRaM</a>

I spent an evening jotting down ideas on paper and jumped straight in yesterday in the shed with the cylinder block. I am making most of this up as I go along...

I need to find a cheap source of brass for some parts but I'll make the end caps tomorrow and start on the base.

Thanks for looking!

[propforward]

Well your first engine is lovely, and also I must compliment you on the video production. Top shelf! Really enjoyed watching it.

Your new engine design looks interesting. I will enjoy following along. Looks like you have already made some really high quality parts, so I have some high expectations for the finished engine.

Nice work all round. I'm a bit of a Joe Pie fan as well. I've learned a lot from his videos - even had some direct dialog with him.

[crueby]

Looks like it will be a very nice engine, great finish on the parts so far.

[propforward]

Inexpensive brass - isn't that the element unobtanium?

[gary.a.ayres]

Looks like a great start.

 

[Kim]

Inexpensive brass - isn't that the element unobtanium?

That's what I was thinking!
When you find that inexpensive brass, be sure to let the rest of us know where you found it!

Your engine looks and runs great!  And your new one is looking good too! 
Thanks for posting your build.
Kim

[scc]

Getting an engine to run that you have drawn yourself is extremely satisfying.    Keep up the good work.     Terry

[Josh-MMS]

Thanks for the words of encouragement gents.

I get a lot of my alu and steel stock from a local job shop for excellent prices but he never has brass. I guess I've spoilt myself with it haha.

[gary.a.ayres]

Can't beat a good old scrap bin!

[Josh-MMS]

One mans trash...

Unfortunately I had a little bit of a setback yesterday.

Snapped an M3 machine tap in the cylinder block... 

I've tried a few ways of getting it out with no luck so I'm not sure what to do now. I think it'll run fine with only 3 bolts but it'll look awful.

If anyone knows a bored EDM guy in the North of England?...

For now I'm going to crack on and ignore it, if everything else goes swimmingly I can always remake the block at the end. It'll give me a nice challenge of making it match the rest of the model.

[gary.a.ayres]

Yes - the guy whose bin I regularly plunder says 'there's no such thing as scrap'. It's true... and it's probably why he sells it (at reasonable cost) rather than gives it away.

But damn! So sorry to hear about your broken tap. It's such a drag when that happens, especially since you have already put so much work into the part. Commiserations.

I don't know how to get a broken tap out, but I'm pretty much a rookie and there may be other forum members who do. The only thing I have tried in similar circumstances is screw extractors, but this hasn't worked for me as the steel of the tap proved too hard to drill into. And M3 would be very small for that approach anyway.

Will be interesting to see what others have to say...

[Josh-MMS]

I ground a few shanks into varying fork shapes and ran the mill in reverse but it has a severe lack of ridgity and they end up walking around the hole, hence it looks pretty chewed up. I dont think it'll be coming out in my workshop, but I'm open to ideas! I'm definitely a rookie too.

Edit: It snapped on extraction too, there's only about 2-3mm of tap in the hole now so I'm also wondering if it isnt straight anymore? Which would make it harder...

[crueby]

The only way I have gotten them out is to use a diamond coated bur in a rotary tool to grind out the center of the tap so the flutes could be pulled into the middle and out.
Its key to tap aluminum with a little oil, and back the tap out frequently to clear chips, or it will grab and break.
Worst case, if it won't come out but will still seal, glue a screw head in the opening. I've never done that. Nope. Not that you can prove!   

[propforward]

Well, one approach is to get a carbide end mill and gradually peck away at it. Seen a few taps milled out that way. It's rough on the end mill. On a multi thousand dollar part it's a no brainer repair, but not necessarily as ideal on a home part. Just throwing it out really. Go on size or undersize, whatever is left can be picked out.

Or go oversize, and put an insert in (make one) if you have room. Although it looks chewed up, it will presumably be covered on the final assembly. That's OK. Still a legit repair.

EDIT: burr on a dremel sounds like a better approach for the home shop, frankly.

[Kim]

You can always try the 'Alum' approach.  I've used that with some success in some cases in the past.

The other thing I've done is to make a donut drill bit (?) that you can use to cut the tap out, then you can plug the bigger hole that's left, and re-do the tapped hole that you just cut out.  Here's an example of a donut drill that I made for one such occasion:


And here's a link to the whole post where I did it.  It has more info on how I cut the tool, etc. if you're interested.  In this case, it was a broken drill bit, but drill bit or tap, it's the same difference.  You need to get the broken tool out and get back to where you started.  https://www.modelenginemaker.com/index.php/topic,5264.msg110367.html#msg110367

The other thing I've seen people do is just Loctite a stub screw head on top of the hole with the broken tap.  If you don't really need it, this can work.  Just remember it's glued on there if you go to take the engine apart for some reason! 

Best of luck however you decide to go!
Kim