Elmer's Tiny in 1/4 scale.

[ttrikalin]

After building my first ever runner (Elmer's Tiny) and my second ever runner (Elmer's Tiny in 1/2 scale)

http://www.homemodelenginemachinist.com/index.php?topic=6231.0

I decided to build Elmer's Tiny in 1/4 scale... So I was in serious need of new tools... Feedback in my first post suggested that the task is not trivial...

BTW, plans are found in this wonderful site... as most of you know ... go to engine #23...

http://www.john-tom.com/html/ElmersEngines.html

A few weeks back I bothered your graces with my log for the stereomicroscope mount...

http://www.homemodelenginemachinist.com/index.php?topic=6383.0

So now that I got a set of small drills from HF and a set of mini endmills from EBay I decided to start with the column...

First, hacksaw to part a small piece of steel... Which I then milled to make square surfaces.

Mill on the floor, lathe on the desk... Mounted on the 4 jaw. This is a Taig 4" chuck that fits my Sherline... It's a bit bulky... I need to get a smaller one... I centered the piece with the indicator, mounted on a home-made base that holds it to the center of the spindle.

Then I turned the stock down to start forming the column... The diameter at this point is 0.189" - it will be turned down further later.

Lathe on the floor, mill on the desk. Indicating a good reference for the Y axis.

Mounting the piece directly on the mill table. So exciting...

... and so dummkopf... the screw of the mounting gear (step block) gets in the way...

... but also the milling collet is practically sitting in the spindle and the headstock does not go so low... so the whole setup was in vain. Anyhow, milling vise. Here I drill the hole that will accommodate the bushing for the crankshaft (and the crankshaft). I started with a #80 drill (why??? - not shown) and then enlarged with a #67 - shown.

Then drill to size with a 1/16". Note that I do not make everything to scale. First I have no tools, second, I think that the shafts will be too feeble if I make them 1/4 scale... Third I could not care less. ;D ;D ;D. I'm sure Elmer Verbung would approve :hDe:

Then I started drilling the hole for the cylinder pivot thingie (shaft). This is a #80 drill, can you see it going all the way through? . I enjoyed drilling with these small drills... it was completely unnecessary though... I made the final hole a #66. Do not ask why. Because.

Then I milled a small flat where the steam ports would be, and I center-drilled (not shown) the first of the 2 steam ports (not shown). I did not use a jig, as Elmer does. I trig'ed out the location of the holes and did them manually. I aimed to make the holes now that the column has not been turned down to final diameter and is thus more rigid...

I decided that the holes should be #80. The centers of the 2 steam ports (intake/outtake) are in a 0.023" distance... There is not a lot of room for larger diameters... This thing will need some serious air pressure to run.. if it ever runs...


AND THEN THE S**T HIT THE FAN. :fan: BIG TIME th_wtf1 !!! The freaking #80 drill broke in the port. I guess I was too drilling-happy...

Anyway, tried to salvage the part by... taking the broken drill out. *bang*

You know the routine. Mill on the floor, lathe on the desk.

I put the stereomicroscope on. This is an image of the problem.

You can see the #66 hole for the pivot of the cylinder on the left, and the small flat I milled to facilitate drilling of the steam ports. You see the port with the drill broken in there. The photo does not do justice to the microscope image... I could see the little bugger in there... :redface2:

Since the current diameter is 0.189" and the final diameter is 0.109", there is some meat on the column I can turn down... Do i decided to start turning down to get close to the outer part of the broken bit.

and then I started eating away the distal wall of the hole, trying to free the broken bit... At this point I could not get the broken part out with a tweezer or anything I have... But running the lathe at highest RMP, it threw the broken bit out. Sweet :-* . (In the photo, the broken drill is still in there.)

After that I turned down the column to its final diameter (for the column "head") of 0.109" and went on to drill the port holes, and the side hole from which steam will come in.
Again, lathe on the floor, mill on the desk. Here I mill the flats on the column. On one of the them (flats) the cylinder will sit.

I do not show how I drilled the steam ports (I did). But after being guided by the force and drilling all the holes and the flats without really seeing wtf i was doing, I decided to inspect...

Mill on the floor, lathe on the desk. After mounting and centering on the 4-jaw, a few peeks through the stereomicroscope...

It is a small bugger.

Here is the hole for the bushing/crankshaft.

This is the flat from the side of the cylinder. Note that the bigger hole on the left does not sit on the center of the flat... I messed up a tad. Also, the flat is wider on the right and narrower on the left, suggesting that the column was not horizontal when I milled it... OK, I'll fix with fine grit wet dry paper. But LATER. The other two holes are the steam ports. When I center-drilled for the one on top I went a bit down, so there is a chamfer there. Oh well. at least the other one is OK. More or less. For done without really seeing what was done... Enough excuses. Next.

This is the other side, the other flat. Again, the bigger cylinder pivot hole on the left and the outtake steam port on the right. (The other port is a blind hole that meets an ipsilateral steam input side hole.) I know, the flat is not good. It bothers me and I'll fix it. LATER.

This shows the side hole that meets the (blind hole for the) input port. The input port is barely visible on the flat, top right side of the photograph.

This is how the input port meets the side hole. Bottom right, on the flat you can barely see the outtake port (essentially a through hole).

And this shows where the intake port stops in the bottom of the well of the side hole...

The column is not complete... I have to fix the flats, clear burrs and turn down a small region in the middle of the column a bit more, as per plans... but this will be done next time. Probably in a couple of weekends... I have a friend visiting and he'll need the room where the home shop is...

Any advice on how to correct the flats welcome...

take care

tom

 

[4wheels]

Hi Tom,
I suppose 1/8 is out of the question? It would be a really small bu88er, eh.
I very much admire your micro engineering and hope one day to build a working steamer on a small brass thimble I bought specially for the task. That was years ago and no doubt it will be years before I attempt an engine. I don't have a clue as to the realitive size of your 1/4 or the 1/2 compared to a "thimble" engine. I'm kinda hoping it's about 1/1.
Anyway keep up the good work and not too more broken drills.
I will be following with much interest.
Cheers,
Brian

 

[vlmarshall]

Lathe on the floor, mill on the table,
I can't see those parts. With a 'scope you are able.

Mill on the floor, lathe in it's spot,
thanks for this thread, showing what's what.

Lathe back again, mill put away,
I'm glad the snapped drill didn't ruin your day.

Now the lathe's gone too, both machines are at rest,
and your workbench becomes the bed for a guest.
;D :big:



Anyway, 'gotta love the little Sherlines for portability. Thanks for sharing the many steps you've gone through so far. I'm envious of your stereomicroscope. I use 'em at work, and wish I had one at home, with a ring mount for my camera on the monocular eyepiece.
Also, I see you're using the popular folded waycovers... I've actually made a set, but realized at the last minute that I'd lose a bit of Y travel with them in place...so I'm working on a modification. ;D

Great thread, keep up the wonderful updates.

 

[90LX_Notch]

Tom,

First off, great start. :bow: Keep up the great work.

I felt the same pain two weeks ago when I snapped a #80 in my column. Since then I haven't had any time to work on mine. (My daughter was born last Friday.)

Where I blew it was trying to do it with the jig. I spent too much time making it only to have it break the bit. I had resolved my self to the notion that I have to remake the column but after reading this I'll give spinning it a try.

To help people understand what you are doing here's a picture of the piston, column, cylinder and bushing. They are all to scale except that cylinder is still attached to the parent material. It is bored and the pivot pin hole is drilled. Also, the rod part of the piston is beefier.

Secondly, geez I wish I had a microscope. You have the way to go there. The thought of remaking the column has really shelved my desire to finish this.

Bob

 

[ttrikalin]

Bob,
The daughter is the important piece of news!!! Kudos! th_wav

I am not skilled so the microscope makes all the difference in the world. I cannot mount it on the mill though. I'm exploring alternatives (e.g., a cheap USB camera with near zoom???) -- Some looney out there has solved the problem... Give spinning a try. I would chamfer the entrance of the hole to remove burrs that hold it in... and get a good magnifier glass or an eyepiece to see if it's out...



Brian,

I'm sure that Jerry Kiefer (one or two "f"s? :hDe can do the 1/8 with his eyes closed and both hands tied behind his back - but I do not think it's for me, my skills or my toolset. (But I do have a couple of friends who are microsurgeons... I guess that these guys are up to this task...)


Vernon,

Nice poem - I'll print and hang on the wall.

Sherlines are great. Pretty accurate for money, very light to carry around, ideal for 30-year old lazybones like me... Also, Anastasia (wife) wants me to do small "metal thingies" -- less swarf oh: .


tom

 

[ttrikalin]

Also, I see you're using the popular folded waycovers... I've actually made a set, but realized at the last minute that I'd lose a bit of Y travel with them in place...so I'm working on a modification. ;D

Yes I have this complaint from the popular design too... What mod are you thinking... do you want to post a how to? (and some G code )

 

[vlmarshall]

...exploring alternatives (e.g., a cheap USB camera with near zoom???) -- Some looney out there has solved the problem...

Nice poem - I'll print and hang on the wall.

Sherlines are great. Pretty accurate for money, very light to carry around, ideal for 30-year old lazybones like me... Also, Anastasia (wife) wants me to do small "metal thingies" -- less swarf oh: .

I've seen a kid's educational toy... called an "EYEclops" I think, that is a USB camera with macro lense, that I've thought about using for miniature work and painting...

The poem... I was half asleep. ;D Seemed like a good idea at the time. Yep, I'm really happy with my Sherline mill, and hope to add a lathe soon.

Lastly, my wife has me making "little metal things" for her, too. ;D

 

[mklotz]

How about a USB microscope?

http://www.thinkgeek.com/gadgets/electronic/9955/

and only $350.

 

[Deanofid]

That's pretty small, Tom! It's a neat undertaking, reducing the size so much. Making tiny parts like this is where my sins become evident. Every thou counts.

What a nice stroke of luck that the broken bit came out by spinning it. You must be living right.

I have one of the Taig four jaw chucks too, and have owned the Sherline equivalent. The small amount of increased mass of the Taig unit actually works to your advantage. A little extra dampening, and a little more fly wheel effect, which is good for small machines like the ones we use, (Sherline or Taig lathes).

Keep up the tiny work!

Dean

 

[vlmarshall]

How about a USB microscope?

http://www.thinkgeek.com/gadgets/electronic/9955/

and only $350.

the Eyeclops "Bionic Eye" does 200x too http://www.eyeclops.com/

You just have to pull it out of that goofy eyeball-shaped housing it's in. ;D

I have one of the Taig four jaw chucks too, and have owned the Sherline equivalent. The small amount of increased mass of the Taig unit actually works to your advantage. A little extra dampening, and a little more fly wheel effect, which is good for small machines like the ones we use, (Sherline or Taig lathes).

Good point... I'l remember that.

 

[ttrikalin]

the Eyeclops "Bionic Eye" does 200x too http://www.eyeclops.com/

You just have to pull it out of that goofy eyeball-shaped housing it's in. ;D

Or, play it kinky or artsy and keep it as is ;D :big:

 

[ttrikalin]

OK, guys and gals... I make the following observations and I try to decide between starting from scratch or adapting...

Picking up the previous thread... I turned down the lower part of the column. You can see the flat on top, and that the cylinder pivot hole is not centered... I made this observation in the original post and thought that the flats were not perpendicular to the (supposedly centered) hole.

So i decided to use 600 grit wet-dry sand paper to "fix the flats". The distance of the flat surface on the column from the wide surface of the solid block from which I machined the column is 0.139".

It happens that a pair of parallels, 2 layers of 3M double-sided tape and a 600 grit wet-dry paper get to 0.140".

and therefore i have a nice and easy setup to put a great flat on the column.

The more I applied the paper, the more obvious it becomes that the flat is parallel to the block surface... but the hole is unfortunately not centered. I overdid it here and there is a bit of a flattening on the round part of the column below the column head... (BTW there's no endmill marks -- the surface is great. )

Measuring with a digitizing software (Engauge Digitizer, http://digitizer.sourceforge.net/) the hole is eccentric by approximately 0.012". This is a very suspicious number. It is very near to the displacement of each of the port holes from the centerline. So I mess up when drilling. The whole set of holes is eccentric by 0.012"...

So the question is... if I make the pivot of the cylinder eccentric by the same amount, do I solve this problem... I think yes, but did not use pen and paper to verify. Not in good mood now .

 

[ttrikalin]

A correction. The holes are eccentric 0.006" to the left... not 0.012". I misstated.

The green line is .109". The blue is 0.007" and the red 0.019".

thanks again,
tom

 

[NickG]

Tom,

Wow that is small!

If the crank and the cylinder pivot hole were on the same centreline and they look to be that's good. But the problem looks like it could be your port holes. The centreline doesn't run right between them, 1 looks further from that new centreline than than the other.

I think you may solve the problem by drilling the cylinder port off centre line by the same difference the column ports are away from the crank centreline if that makes sense? Not sure if drilling the pivot off centre would do the same as that - hard to envisage isn't it! Do you have access to 3D CAD? that could tell you. If you give me all the dimensions I could mock up a quick model that should tell you.

Nick

 

[ttrikalin]

Nick, thanks for offering...

... but I think I got it. It will work by offsetting the cylinder pivot by 0.006" to the correct direction. The whole complex of pivot hole and port holes is eccentric. :-

Next in line is the bearing and the crankshaft...


Normally I should post these few photos in the booboo section ... but I think what the heck, my new mess-up is part of the build... :big:
So I turned two bearings out or brass, and I'll have to turn a 3rd one... Well, my bearing number one I kind of lost *club*... It fell on the floor... after 15 minutes of inspection and methodic search I could not find it...

Till now I realized that when I mess up and my work goes down the drain :toilet: it's better to let it go, and go for a beer... *beer*

But I had to turn another one... I polished it with 400 grit paper, and I accidentally dropped it on the floor. I put it in a small zip bag I had leftover from some transistors, but it had a hole in the bottom as big as its opening on top... But this time I got it right next to my desk's foot (in the middle, between the 2 strings of swarf):

Then started turning the crankshaft out of a steel bar I got from home depot. Really bad stuff. Difficult to get a decent finish. I aimed to turn the whole crankshaft from solid.

To make a long story short, I tested the fit of the bearing to the shaft. I knew it would be tight (hole 0.033", shaft 0.0335") and I press-fit (why?). I managed to get the bearing stuck on the shaft and to bend the shaft as well. *club* *club* *club* *club*... the whole thing is scrapped. Anyway... it's a real build with it's ugly turns and the occasional success... next time I'll nail the little mother down...*knuppel2*

*beer*
cheers,
tom

 

[zeeprogrammer]

I sure hope this doesn't come across wrong...

It reminds me of a few of my evenings...the ones punctuated with 'crap'...'crap'....'crap again'...'fooey'...I sometimes get the feeling that if someone were watching me..it would be a great laugh...like watching Laurel and Hardy.

I sometimes forget myself...but there's no reason why making boo-boos can't be fun either.

I don't have the skill to answer your question about correcting the eccentric...but I can tell you I'm enjoying the posts and the learnings.

 

[ttrikalin]

I sure hope this doesn't come across wrong...

I does not come across wrong Zee... I feel the same way... Actually sharing the booboo and the poopoo has a ... cathartic effect (pun intended).

It reminds me of a few of my evenings...the ones punctuated with 'crap'...'crap'....'crap again'...'fooey'...I sometimes get the feeling that if someone were watching me..it would be a great laugh...like watching Laurel and Hardy.

I had this same feeling a few hours ago...

take care,
tom

 

[ttrikalin]

Today is another day. The sun would shine in the morning were it not for the clouds, the birds would sing along to my humming were it not for the rain and the cold, and I would get home earlier that I did were it not for a few fires at work.

What is for sure, is that I had all the motivation in the world to attack the little mother that gave me a hard time yesternight... :-*

So here's tonight's adventure with the little bugger... Second attempt to make the bearing and the crankshaft, and also the opportunity to correct my blunder that was described in previous posts. Briefly, I misplaced the lovely holes for the cylinder pivot and the steam ports by 0.006".

First, I turned the brass bearing. It downed on me that the best way to align all holes is to move the crankshaft hole by 0.006" in the direction of the error. Therefore, I decided to make an eccentric crankshaft bearing. Eccentric by 0.006", the amount of the error.


First, I chucked a piece of brass in the 4 jaw, faced, and surfaced it. I center drilled and drilled a 0.033" hole deep enough (>0.125"). Then, I offset the piece horizontally by 0.006", as shown below. Starting position is 0 (do not mind the shadow of the indicator)

and ending position at 0.006":

Then I turned down the external diameter to size. 0.0625" for the rightmost part, 0.081" after the step to the left.

Then I parted off to length (0.125"). A problem was that after parting off a sizeable burr was left on the part. So I ... chucked on the 3 jaw and faced... :shrug: This is after the facing. (My Sherline is huge after all...)

And this shows the eccentric hole that corrects my previous error.

Now on for the crankshaft. The home depot steel bar I was using yesterday was awful. So I tried a steel nail, which I turned down. I will machine the crankshaft out of the solid.

This is the shaft, turned to final diameter, with the bearing on it. The bearing fits nicely, with not perceivable play, and slips in and out without sticking.

Then I parted the crankshaft allowing for enough meat to make the crankshaft disk and the crankpin.

The next step is to put this on the lathe shaft first and turn the crankpin that is eccentric by a few thou. Now I do not have any collets... so I will improvise. I have an idea... I plan to make a one time "collet"...

1. Sandwich two flat pieces of ally or Delrin together and chuck on the 4 jaw.
2. Drill right where they meet a 0.033" hole, and without unchucking
3. put the shaft in the hole, perhaps with a dab of glue.
4. machine the crankpin eccentric to the shaft by the proper amount
5. separate the parts of the "collet" and clean in acetone.

I fear that If I do not do a sandwich it will never come out of the "collet".

What do you think? Am I on for yet another booboo?

 

[Russel]

Do you have a pin vise?

Many pin vises are designed to be mounted in a chuck. Also, and your mileage may vary, rather than facing the bur off of your offset bushing I would have put the part in a pin vise and honed it with an oilstone or maybe 1000 grit wet or dry sand paper and some thin oil.

Just a couple of ideas that you may fine helpfull.

Russ

P.S. I admire you for taking up such a challenge! It's microscopic!

 

[hammers-n-nails]

while were talking about micro-steam i found this a while back http://steamtraction.farmcollector.com/Steam-Engines/Smallest-Steam-Engine-in-the-WORLD.aspx how will the overall size of yours compare?