Steam Tractor 3/4" (Rudy K)

[Kim]

I’ve been off doing house projects for the last several weekends. I’m not done on that front (are you ever?) but I took today as a play day and made some modest progress (which is all I ever make).

Today’s goal was to get the steam dome attached to the boiler.

But before I could do that, I needed to make a larger hole in the bottom.  I started by drilling a couple of larger holes there. This worked OK, but it bent the brass all about.  After reshaping the brass base, I moved to the mill and milled out the hole.

To make the saddle square with the mill, I placed a round bar in the saddle and adjusted the thing into place by eye.


Then I used a 3/8” mill to rough out the hole (moving very slowly and carefully!)


Next, the mounting holes were drilled:


The mounting hole positions were then transferred to the boiler casing, and drilled and tapped #2-56.


And here’s how it looks.  I’m using the SCHS screws inside here since you won’t be able to see them, and they are a LOT easier to insert and remove than a hex head.


My next project will be to make the actual dome.  Rudy shows a dome formed from then aluminum, and I think I can get my mind around that.  But what I haven’t figured out, is how do I get three tabs on the underside of the aluminum?  With one piece beaten into a dome shape, I’m unclear how to get tabs out the bottom. And aluminum doesn’t solder well, does it?  So, I’m contemplating exactly how to fab this up.  Any ideas?


Thanks for checking in,
Kim

[crueby]

Nice!  Bet that was a pucker-operation milling that opening!
 

[b.lindsey]

All's well that ends well Kim. Glad you found a bit of shop time.

Bill

[10KPete]

I've been staring at that drawing for a long time and I still can't figure out what it's supposed to look like!! It's not all there. Some important information is missing.

I think it's a baffle...???

Pete

[Kim]

Thanks Chris, Bill, and Pete!

I've been staring at that drawing for a long time and I still can't figure out what it's suppsed to look like!! It's not all there. Some important information is missing.

Yeah, I guess I didn't include enough info here.  Sorry about that.  I should have been more complete with the info I provided along with my question!  I'm sure the GA drawing would help you a lot.  I didn't think to include that.

That item is just supposed to be a dome cover for the part I mounted today.  The weird holes cut in it are to make room for the throttle and steam pipe to exit.  But it's really just decorative.

The thing that is baffling me is how to get those tabs on the bottom.  They are supposed to clip inside the existing column that I mounted today to hold the dome cover on.  But I'm still working on how to get the tabs in there.

I'll work something out undoubtedly but was hoping someone could point out the obvious thing that I'm missing.

Thanks for looking in!
Kim

[b.lindsey]

Kim, why not just machine it from a solid piece of aluminum and leave a collar around the bottom rather than the three tabs. Just thinking out loud here.

Bill

[Kim]

That's not a bad option, Bill.  I was also considering making the sheet with a few tabs sticking out off the edge and bending them back underneath.  But I think that would distort the round edge of the dome quite a bit.  From the solid may be the easiest.

Someone else, in a different build thread on HMEM just made a dome and riveted it in place - no plans to be able to remove it I guess?  Not sure I like that solution.

Kim

[Johnmcc69]

+1 on Bills idea. Turn a light press/interference fit & pop it in the stack. Then you can hold the "collar" in the vice & mill the slots in the dome.

 John

[b.lindsey]

I might mill the slots first assuming there is anything to still hold on to to turn out the inside base for the thin collar.
Bill

[Tennessee Whiskey]

If I’m reading it correctly, this part is only  .0156 thick. I would think that is going to be hard to hold for milling. Maybe a job for snips and hand forming.

Cletus

[Dave Otto]

I have also been studying that drawing and I'm also confused about the tabs. I don't see how it could be made from one piece of sheet sheet metal and look like the drawing.
I wonder if the spring clips are added after the dome is formed, see attached.

Like the other guys have indicated I would be tempted to machine it  from solid and make it as heavy as possible.

Dave

[b.lindsey]

Yes but it's decorative I think so could be made from solid and leaving the domed part solid. But I haven't seen the plans so Kim will have to say.

Bill

[Kim]

That's an interesting little insert you designed there for the tabs Dave!  I like it

However, I think I'm leaning toward turning it from solid.  I think I'll get a few minutes in my shop today, so hopefully I'll give this a try!

Thanks for all the thoughts on this everyone.  I do appreciate it!
Kim

[Steamer5]

Hi Kim,
 An interesting part! First look a couple of days back was, like you 
Just had another look & the drawing makes sense....LED moment! The weird “cut outs” on the right on the top diagram suddenly made sense, must have had a good nap , pipe work penetrations!
I’d go with Dave’s option, make the spring from steel, a bit more robust than aluminum. Use the bolt hole to hold it in, guessing that MAY also hold the dome in place.

Keep up the good work

Cheers Kerrin
.

[Kim]

Interesting perspective, Kerrin!

You're making me re-think Dave's idea there.  I'm kind-of liking that now.  The top hole in the dome is for the fake pressure gauge. But I can use that as a way to mount the spring too.  That's not a bad idea at all!

I was starting to work on the "from solid" idea this morning, but only got a little way.  I was still debating on the order of operations - I would like to turn the base size, then cut it off, hold it in place with the base insert collar, and turn the dome.  But then how do I hold it to mill out the cut-out sections?  And if I did the cutout sections first, I'm not sure I can hold it in the lathe chuck to make the dome.

Now I'm thinking I may go back to hammer forming the dome, as Rudy describes in his instructions, and making the spring tabs like Dave's drawings, and holding them together as you describe, Kerrin.

But it will be several days (if not weeks) before I get another opportunity here.  Busy summer...

Thanks for all the help everyone!
Kim