Question regarding Tiny

[1Kenny]

Hey Alex,

Marvel oil was made for top end lube for steam engines. It is a very good lube and has time proven it's self in many types of engines. I have it in my shop.

Use any oil you want, your engine will tell you what it likes. The only mistake you can make is useing NO oil.

My "Tiny" has been running on Mobil 20/50 V-Twin oil, as does my lathe.

 

[shred]

I just got done making a Tiny last night (still needs a little cleanup, but it's running-- photos later). It's the first Elmer Engine I've built, and also the smallest.

It took a couple days-- it would have been done a lot sooner except I got lazy and snapped my #57 drill drilling the column ports and was so irritated that I trashed the part trying to get the broken end out (in hindsight, there was an easy workaround, but I didn't see it until too late :?) So, I made a second column and used a #56 drill, which doesn't seem to have affected anything.

I did a few things different from the instructions--

-- I skipped the drill jig and just calculated where the column ports go and did all the drilling in the mill-- IIRC the ports are close enough to .05" either side of the centerline.

-- I made the cylinder out of 3/8" brass rod. Flatten the column side to make the mating face and it saves on rounding later.

-- Not having a 2-56 setscrew on hand, nor the tweezer-operated hex key one would need, I counterbored for a SHCS, which technically helps with the balance, though the actual need is a little doubtful.

The only other boner besides the column I made was tapping the steam connection 5-40 before realizing I didn't have a 5-40 die to make the matching part. Ah, well, I'll drill out a bolt or something.

Elmer's a funny guy, sneaking a #65 cross-drill of some 1/16" drill rod in the plans. :wink:

 

[Alex]

Congrats on your new engine. Hope to see some pictures later.

 

[rake60]

As we've said before shred, plans are just for reference.
If we all made then exactly to print you'd be able to buy them at
WalMart for $9.99

My last project engine called for #70 drill holes through a 1/16" pin for a
keeper wire. My mill won't grip anything smaller than a #60 so
I drilled .040" holes through the pins. .010 wall thickness if it's dead nuts
on center. First one turned out fine. Second one broke through the side,
so I made a third one. The third one lead off and broke through the side
again. I said.... well never mind what I said, but I used it anyway. It
was for a keeper wire. It works just fine and nobody will be killed or
injured if it fails.

I guess what I'm trying to say is I think your revisions show the type of
thinking that makes a home modeler.
One final comment....

 

[shred]

As we've said before shred, plans are just for reference.
If we all made then exactly to print you'd be able to buy them at
WalMart for $9.99

Yeah, it's amazing how much you can get away with on a wobbler-- so long as the port holes are in about the right places, and everything else is more or less in rough alignment, it'll work.

My last project engine called for #70 drill holes through a 1/16" pin for a
keeper wire. My mill won't grip anything smaller than a #60 so
I drilled .040" holes through the pins. .010 wall thickness if it's dead nuts
on center. First one turned out fine. Second one broke through the side,
so I made a third one. The third one lead off and broke through the side
again. I said.... well never mind what I said, but I used it anyway. It
was for a keeper wire. It works just fine and nobody will be killed or

Yeah, I'm working on pics. I was going to document making the parts only to discover the camera wouldn't cam anymore.

I ended up doing the cross-drill with a tiny carbide burr since my drill set only goes to #60-- they're fairly easy to come by disguised as Dremel bits or PCB mills.

Anyway, to the point in the "how do we do it" thread, hopefully my changes help highlight to new builders that just because you don't have a #97 drill or 1/7-16 tap or whatever, it doesn't mean you can't build something-- you might have to get a little more creative is all.

Oh yeah, Alex, I reamed the bore, though Elmer's instructions are to bore it with a tiny boring bar. Doesn't seem to matter much. Elmer did a lot of things on the lathe I did with a mill just because it made more sense to me that way or matched the tools I had better.

 

[Bogstandard]

You want pictures, well here's a couple. I don't usually release pics until the job is done and dusted.
Started today on a UK version of your 'Tiny', it uses the port setup and dimensions from Tubal Cain's 'Jenny Wren' combined boiler and engine.
It called for a two part crankshaft, with the crankpin inserted into the crank disc. But I find it easier just to chuck up in the 4 jaw and turn the pin while making the crankshaft. This was done on my 'old' atlas lathe and is made of silver steel (drill rod).

Took about an hour to make.
The pin will be cut to length after assembly.


John

 

[Alex]

John,

Wow, that's a tiny crank! Great job!

 

[shred]

Low-res cell-phone pic:

 

[Bogstandard]

Lovely work.
It's so nice to see so many variations on a theme and the way people get around problems.
Wouldn't life be dull if everyone made things exactly the same.

John

 

[1Kenny]

After reinstalling the rod pin a half dozen times useing everything from locktite to super-glue I now see how to do it. Make it as one unit.

 

[Alex]

Nice engine Shred. Is it all brass?

Kenny, what do you think about soldering the crank pieces together? Another solution might be JB Weld. I've used it on one of my steamer locos with great sucess.

 

[1Kenny]

Alex,

I haven't tried JB weld. If it comes out again I will try it. I think John is on the right track with making it one piece. I did solder the the crank wheel to the shaft through the column. The big part of the problem is me as I am running it in the way too fast range.

Shred,

That looks real nice.

Kenny

 

[shred]

Nice engine Shred. Is it all brass?

Kenny, what do you think about soldering the crank pieces together? Another solution might be JB Weld. I've used it on one of my steamer locos with great sucess.

Thanks. It's almost all brass, except for the pins and crank disk which is currently an interesting shade of purple-gray from a soldering attempt. I started out making a 12L14 steel column, but trashed it due to impatience (see above) and had a short length of .700" brass rod lying about, so that became the new column.

The pin that holds the spring on also isn't brass-- it's an IC socket pin from a circuit board that had an interesting look to it and was a convenient size.

2nd Kenny's comments on the crank-- the offset hole I drilled with an undersized 1/16" drill (I didn't know that at the time), and it press-fit nicely, but the center hole, with what turned out not to be the same drill bit, came out as a loose fit and all manner of locktite, superglue and solder didn't help it stay put how I wanted it without making a mess, so I ended up peening the end of the shaft a little oval with a small hammer and that's holding up.

I came close to making a whole new crank disk-- it's not that much work and I made that one too thick to begin with, requiring some extra cutting elsewhere to make the piston rod align properly.

If I were to do it again, I'd consider the one-piece construction, but my lathe skills might not be all there for that level of work. Failing that, I'd go straight to the undersize drill and press-fit-- I prefer adhesives that can be removed in a pinch in general, but they didn't work well enough on this part.

 

[Alex]

How much smaller than the rod is the hole? I have a drill bit that is .004" smaller than the crankaxle and pin. The hole will of course end up a little bit larger.

 

[1Kenny]

Thats where I feel I messed up, not under sizing the crank wheel holes so the shaft and rod pin would have a press fit.

 

[Bogstandard]

The way I get a good press fit on small bits is to drill the next size smaller than the shaft then using a pin chuck open out each end of the hole to the correct size for the shaft but leave a small area, maybe 0.010" in the middle of the hole at the smaller size. This allows a good force fit but not too much where it will damage the parts, this also allows you to use a locking adhesive as well.
If you have drilled all the way thru and the shaft is a sliding fit, mark where the part should be located on the shaft and using a centre punch, put lots of little centre 'pops' regularly spaced around the shaft where the part goes, this should then allow the part to be force fitted onto the shaft in conjunction with adhesive should make a very strong joint. If the shaft is from very hard material that won't 'pop', you can, if it is on a part that is not seen, centre pop around the hole at both ends, this will effectively reduce the size of the hole at either end and again in conjunction with adhesive should give a nice tight fit.
Don't use a hammer to force fit small parts, all it does is deform the hole and make it slack. I put a piece of soft metal in the drill chuck of my miller or pedestal drill and use it like a press, a vice can also be used for pressing together small parts.


John

 

[RollaJohn]

If you have drilled all the way thru and the shaft is a sliding fit, mark where the part should be located on the shaft and using a centre punch, put lots of little centre 'pops' regularly spaced around the shaft where the part goes, this should then allow the part to be force fitted onto the shaft in conjunction with adhesive should make a very strong joint.

John

Don't get carried away with the depth of the dimples. I witnessed a 'know it all' who had heard of this procedure place deep dimples around the shaft thus raising a large rim around the craters. When he started to force the shaft into the bearing race the ridges rolled over onto the shafts surface making a very tight fit. So tight the shaft quit moving.... he got a bigger hammer then forced it until the parts were basically welded together!!
He was following the rule: ...If it jams force it. If it breaks it needed replacing anyway.

So remember you can always dimple a little deeper if it is too loose the first time

 

[gt2ride]

Here is my Tiny. Setting on my 6in Square.

Just kidding. Here is a closer pic.

 

[1Kenny]

gt,

Good looking engine. I like the brass ring on the spring.