Elmer's Tiny in 1/4 scale.

[Deanofid]

Nice work, Tom! Next time you build something big, it's going to seem so easy.

I've watched some of Tryally's videos in the past. That feller really knows his onions.

Keep up the good work. Don't be a stranger!

Dean

 

[4156df]

Tom,
Very nice work. You've proven the old adage: If at first you don't succeed, try, try, again. Also, thanks for the lead on "tryally".
Dennis

 

[90LX_Notch]

Tom,

Congratulations! That's awsome man.

Bob

 

[Blogwitch]

Tom,

I have to applaud your perseverance to get the job finished, and really I should have butted in long ago when I first saw you struggling to get it done.

I only have a large lathe, but small sizes can easily be turned on it. I had a job a few years ago where 0.005" diameter by 3/8" long was required, with a sized head on one end, 50 of them. I had no idea what they were for, I just made them.

The secret is not to fine cut down to size, that usually ends up breaking the pin. What you do is cut down to a much larger diameter, in your case, until you had no interupted cut after doing the offset. Once that stage is realised, you then hit it with one large cut that takes you down to finished size. Doing it that way, you have the support of the large round pin all the way back to the crankdisc. This is a common method used when cutting soft plastics, as if you fine cut down to size it turns out all shapes and sizes because of flex in the material, by doing the 'one hit', you find you can cut them perfectly parallel, time after time.

Bogs

 

[ttrikalin]

- All, thanks for the encouragement...

- Indeed Luis Ally is a very good teacher, for me at least... I enjoyed his videos and he seems a cordial fellow...
(My wife even knows of him "as that dude from Brazil" and she even watched some of his videos with me...)

- Bogs,
thanks for the advice - you should've chimed in earlier and could've saved some frustration ;D so take it to the finished diameter with a heavy cut.
I'll follow this when cutting the air tubes...

t

 

[ttrikalin]

The cylinder... complete but still on the parent material... Will be parted of in the lathe when the time comes... Will post how it was built... a bit later...

The cylinder fits in a mental box of 0.078" x 0.094" x 0.114"... bore is 1/16"... Note that it is rounded on the lower part... On the upper surface I put 2 holes, one for the pivot pin (0.032" -visible) and one for the steam ports (0.014" -barely visible, distally by 0.059" from the aforementioned one... ).

Now I have to go watch sex and the city II with me wife... Getting ready ( *beer* )
Any of you seen it? ;D If so did you like it?

take care,

t

ADD-ON MESSAGE:
:-[ back home after the film th_bs - good grief oh:

 

[ttrikalin]

OK, this piece I CNC-ed. The first run was a disaster, as the X axis of the mill had 7 thou of backlash and this ruined the part. To take the back lash out I had to disassemble the below covers and get to the anti backlash nut and I was postponing it... I had learned to work around the backlash manually.

After adjusting all axes, I am at <2 thou of backlash (Sherline suggests 3 to 5 thou) and I decided that the cylinder can live with that, especially if I program the CNC to approach from the same direction (which I never did). Funny though how this backlash is extensive for the size of the part.

Start by using a broken #80 drill (I have plenty of those - broken) as a pointer to position the head approximately to the centre dimple of this faced 0.250” stock.

The round surface is concentric to the cylinder bore (to mill accuracy) and would suffice to center the cylinder using the 4 jaw on the lathe.
The flats are perpendicular or parallel to the cylinder’s flat (the distal face, not shown), and equidistant from the axis of the bore (again to mill accuracy). They will be used to position the cylinder for the pivot pin and steam port holes.
I admit that I could’ve machined the part much better, taking off the 1-2 thou of the backlash with a bit more careful programming...
next time...

Out of the vise...

Drilling the steam port (#80 carbide drill). The piece rests on a parallel and pinched in the vise. I did not square the vise before doing that -- but luckily it was close enough, and to such small distances the error is negligible... I used an edge finder to indicate on the flat surfaces...

A laser pointer shines through the bore -- and through the 0.014" steam port that is exactly at the bottom of the bore.
Do you see the yellow/red dot just below the point of the drill? This is the shine through the port... Wish I had a better picture...

Cylinder on the parent material, indicated and with holes drilled...

Coming next the pivot pin that will be press fit on the cylinder... and perhaps a video of the CNC cut...

take care

t

 

[ttrikalin]

The pivot pin. The diameter is 0.0005” wider for 0.020” in the left end, from where it’ll be press-fit in the cylinder...

Press-fitting the pivot pin... on the mill... McGyver moments once more oh:

By 0.020”...

take care,

t

 

[kcmillin]

t, sorry to hear about the movie experience, *bang*.

I am really interested in this tiny little engine, pretty cool stuff.

Kel

 

[zeeprogrammer]

I've been following along.
Working on stuff this small takes a lot of patience and skill. Good work.

I heard about the movie from daughter...she went with girlfriend and 'boy'friend...dressed up like the cast. They looked great.

That's right. I meant what I said.

 

[SAM in LA]

Tom,

Your build is very interesting. I can not imagine making anything so small with my lathe. Keep up the good work.

SAM

 

[ttrikalin]

This is a video of the cut...

[ame]http://www.youtube.com/watch?v=pcU6Sqx9AZ8[/ame]

 

[ttrikalin]

Thanks to all for dropping a line... Yes, the film was pretty horrendous... :-\ for our (anastasia's and mine) tastes that is... but we're not from the states and there's likely a cultural barrier that prevents us from enjoying it. I'm sure it's full of cultural refs : and pointers that we're oblivious to... Yeah right... Enough with the th_bs ...

I am not happy with the cylinder, and I will make a new one.

1. I want to programme the cuts so that the 1 or 2 thou of backlash of the Y or X axis have minimal effect (approach from the same direction and what have you.
2. I want to bore the cylinder's inside to clean up the shavings of brass that the press-fitting of the pivot pin pushes in the cylinder, and to have a great surface... So I'll change the bore to 0.047" instead of 0.063" (current)... this will make the walls a bit beefier...

I am getting close to finishing the little bugger and I wish it will run...

Oh well, we are still a bit far away from that...

 

[kcmillin]

Having never seen the movie myself, I can say it has nothing to offer :big:

I'm pulling for ya. These little steamers seem to be quite the challenge. But you are off to a great start. and CNC, shoot, you got it.

Kel

 

[ttrikalin]

Found some time to get to the little engine... How easily did this thread slip to the 5th page... people are very active...
I had to make the cylinder 6 times... :-[ This is the 6th...
Following advice from Jerry G I used blue loctite to secure the pivot pin and then drilled the cylinder's hole (bore).

Then I cut off the cylinder with the slitting saw, mounted on the home made arbor.

Cylinder with pivot pin on the pink ruler...

A better view through the microscope...

The orifice of the hole (0.044”)...

Observe this setup... the laser pointer is mounted on the green vise and shines the assembly of the column and the cylinder/pivot pin...

In fact the beam is reflected on the base of the column and into the hole of the cylinder.
In the next photograph you can see the red light through the outlet port of the column (a through hole), which aligns perfectly with the port of the cylinder... :-*

The red light you see through the outlet port is the shine of the distal wall of the cylinder interior...

If you change the angle of the cylinder, no light...

Next, the piston... and then the flywheel... and then we're almost ready for a test... then tears :'( then *beer* ...

Take care,

tom

 

[SAM in LA]

Tom,

You are working in a completely different world than most of us.

I am truly amazed with the precision and the smallness of the parts you are making.

SAM

 

[ttrikalin]

Hardly, Sam, hardly...
Thanks for watching... If this runs I'll start on an IC engine perhaps the Lobo Pup that Gail in NM designed...

t

 

[ksouers]

Tom,
Amazing stuff.
Way too teeny tiny for me.

I've suspected for some time now that you were a doctor.
Now I'm thinking of amending that to arthroscopic surgeon.

 

[Blogwitch]

Tom,

Now you are getting to the air in stage, maybe a little pointer on the way I achieved mine.
If you have access to syringes, the needles are a perfect job for the inlet stub.

For the very fine flexi tube, I used the tiny sized silicon tube used by European fishermen as shock leaders when using what is called a 'pole'. In the US try here.

http://www.smallparts.com/Medical-G...383597011&pf_rd_p=1261382302&pf_rd_s=center-3

The stuff we can get goes down to minuscule sizes, and is fed onto the needle inlet and wrapped with a couple of turns of very soft wire to keep it in position. Another more robust connection was made well away from the engine to drop the tubing size down to the one going to the engine, this kept the model itself looking more presentable.
Available here, second one down.

http://www.tidaltackle.co.uk/prods.asp?cID=2&sscID=52


You can see what I mean on this vid, although this is a lot larger than the one you are making, the air inlet was one of the major problems.

[ame]http://www.youtube.com/watch?v=76_TtDfYPCo[/ame]


Bogs

 

[ttrikalin]

kevin,
I am an MD but not a surgeon - in fact I do more theory and mathy stuff and do not see patients -- researching under the aegis of a Boston establishment... So no professional skills at work - evident from the number of parts I've scrapped till I get a relatively good one...

bogs,
I did have some thoughts on supplying air... I like your solution very much and I'm sure it'll work... I was going to apply lessons learnt from McGyver moments of times past. I shall post an example in my next reply... Is this tiny your own design? Beautiful and so smooth a runner...

tom