Author Topic: Ultra Tiny (1/4 scale Tiny)  (Read 22918 times)

Offline 90LX_Notch

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Re: Ultra Tiny (1/4 scale Tiny)
« Reply #30 on: January 21, 2017, 05:16:20 PM »
The first order was to fix the flywheel bind and reassemble the lower end. 

Picture one shows the shim on the crank.
Picture two shows a slight .028 counterbore that I added to the fly wheel.  This was done to create a pocket for the super glue to set in.
Picture three shows the crank and flywheel reassembled.

Note- Due to the size of the engine I elected to use loctite and super glue when originally assembling it two years ago.  The other areas where they were used will be  forthcoming as I further reassemble the engine.

As of today I am debating wheather or not to make a new cylinder.  The original has a blemish on it that has bugged me from day one.

-Bob
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Offline b.lindsey

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Re: Ultra Tiny (1/4 scale Tiny)
« Reply #31 on: January 21, 2017, 05:56:32 PM »
Looking forward to seeing it reassembled and running Bob. I remember seeing the body of it a few years back at CF, so I know how small it really is!!!

Bill

Offline 90LX_Notch

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Re: Ultra Tiny (1/4 scale Tiny)
« Reply #32 on: February 01, 2017, 04:31:00 PM »
I haven't had much shop time as of late but I did manage to Loctite the nipple in.

It's pretty straight forward.  I used a piece of .020 music wire with an angle ground onto it as an applicator to prevent the Loctite from closing the port off.  The nipple was held with  a pair of tweezers and the music wire was dipped into a puddle of Loctite.  This allowed for a small amount of Loctite to be dabbed around the nipple.  The nipple was then gently pressed into the column and any excess Locite was wiped away.

The engine was then placed in a jar that has a hole drilled in the top and vacuum was applied using a hand held vacuum pump.  This insures that the Loctite will totally cure.

Red Loctite was chosen because originally the nipple was a press fit which failed.  Before Cabin Fever I had dabbed some superglue around the nipple; but, that did not work as the nipple became unseated at CF.  The Red Loctite is nice because it isn't an instant bond which allows for adjustment of assemblies.  Also, excess can be wiped away for a cleaner appearence.

-Bob

Ps: Slowly getting there Bill. 
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Offline b.lindsey

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Re: Ultra Tiny (1/4 scale Tiny)
« Reply #33 on: February 01, 2017, 05:10:58 PM »
Interesting trick with the vacuum jar Bob. Can your really tell a difference in the cure time?  Boy that engine is well.....um.....Tiny!!!!!!!!!!!!!

Bill

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Re: Ultra Tiny (1/4 scale Tiny)
« Reply #34 on: February 01, 2017, 05:24:14 PM »
At one show I attended there was an older guy who had an engine about that size mounted to a finger ring.  A tiny hose ran up the sleeve of his shirt to a rubber bulb in his armpit.  A bit of chicken dancing and he had the engine running.  I've also seen something similar done with the engine mounted on a tie clip but who wears ties to engine shows these days?
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Offline 90LX_Notch

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Re: Ultra Tiny (1/4 scale Tiny)
« Reply #35 on: February 02, 2017, 03:05:03 AM »
Bill-  When I originally assembled it two years ago I found that the Loctite would not cure even after two days.  I had used it on the pivot pin for the cylinder and it would just pull out.  Then it hit me, it must be anaerobic.  That is when I came up with putting it in a vacuum container overnight.

Marv-  I've seen the tie clip engine at CF.  It is about the size of the 1/2 scale Tiny that I did years ago.  This is half the size of that one.  I like the ring idea.  The stone on my college class ring is a .500 x .375 ellipse.  This engine could actually fit underneath it with room to spare.  The ring would make a good back drop for a picture. 

-Bob
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Offline zeeprogrammer

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Re: Ultra Tiny (1/4 scale Tiny)
« Reply #36 on: February 02, 2017, 11:30:09 AM »
Man you really have to be careful with the parts. So easy to toss out with the swarf.

Looking forward to the run.
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Offline Doc

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Re: Ultra Tiny (1/4 scale Tiny)
« Reply #37 on: February 02, 2017, 03:55:32 PM »
Bill-  When I originally assembled it two years ago I found that the Loctite would not cure even after two days.  I had used it on the pivot pin for the cylinder and it would just pull out.  Then it hit me, it must be anaerobic.  That is when I came up with putting it in a vacuum container overnight.



-Bob



Bob I have to remember this trick I knew Loctite only sets up with the absence of air and presence of (is it copper ions) any way never ever gave it a thought about creating a vacuum chamber  :praise2:


Offline 90LX_Notch

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Re: Ultra Tiny (1/4 scale Tiny)
« Reply #38 on: February 03, 2017, 02:52:37 PM »
Karl- Boy do you have that right about being careful with the parts.  During this process I lost the original pivot for the cylinder.  So, I made a new one.  I picked it up with tweezers and didn't have it quite right.  The new one shot out of the tweezers to never be heard from again.

This did run the first time I put air to it (see YouTube video in this thread).  That was the only time that I ran it prior to this year's Cabin Fever. I am pretty sure I know why it failed to run this year.  I would dip it in airtool oil to lubricate it.  I believe the airtool oil attacked the superglue because the flywheel had loosened up. 

Doc- It took me a while to figure it, but it solved the problem.  It was one of those "duh" moments.
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Offline 90LX_Notch

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Re: Ultra Tiny (1/4 scale Tiny)
« Reply #39 on: February 03, 2017, 03:12:11 PM »
During the dissassembly to figure out what went wrong, the pivot pin pulled out.  It is .016 x .150 and was originally cut to final length when the engine was assembled for the first time with wire cutters.  This caused a problem by leaving a burr at the end of the pivot that would not pull through the column.  Something had to give and it was the pin pulling out of the cylinder.  This created a challenge for reassembly.  A fixture was made that would allow the pin to be set to the correct depth in the cylinder and insure that it was square.  The same techniques for applying and curing Loctite to the nipple were used for the pin and cylinder.

Picture One shows the cylinder, pin and fixture.
Picture Two shows the pin's height being set.
Picture Three shows the cylinder against the face of the fixture after being pressed onto the pin.
Picture Four shows the final results.
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Offline 90LX_Notch

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Re: Ultra Tiny (1/4 scale Tiny)
« Reply #40 on: February 04, 2017, 04:48:50 PM »
I almost threw the damn thing across the shop this morning and called it quits.  I put the cylinder and piston together and mounted them on the engine.  Everything turned nicely.  I made a new retaining collar and put that on the end of the pivot.  I set the collar and everything was good.  My compressor is unavailable right now; but, I was able to use the handheld vacuum pump by switching the hose to the outlet port to send air to the engine.  It was enough to push the piston down.  Great! Everything looked like a go. 

So, I setup the tire inflator and said what the heck, we'll see if it will run.  Well, while I was trying to get it to go the flywheel loosened up again.  The super glue will just not work the way I did it with the counter bore.  Okay, dab a little on the crank and set the flywheel, then use the Loctite to fill the c'bore.  That seemed like a great plan.  During the execution of said plan, the super glue instantly bonded the flywheel to the crank.  The only problem was that this occured at the very end of the crank.  No problem, a little acetone should fix that.  Well, it didn't want to loosen up like the other times I used acetone.  You could hear the air escape from my lungs.  I kept at it and finally did get the flywheel off.

This time I used the Loctite on the flywheel.  I hope I got it right because that will be a real PIA to undo.  It's in the jar curing now.  I'm going to see if I can retrieve my compressor so that I have a better chance of getting the engine to run during the next attempt.

-Bob
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Offline zeeprogrammer

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Re: Ultra Tiny (1/4 scale Tiny)
« Reply #41 on: February 04, 2017, 05:03:41 PM »
I almost threw the damn thing across the shop this morning and called it quits.

I'm happy you didn't. Keep at it!  :ThumbsUp:
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Offline PStechPaul

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Re: Ultra Tiny (1/4 scale Tiny)
« Reply #42 on: February 04, 2017, 11:24:35 PM »
Perhaps you could make a key by drilling a small hole in the flywheel and shaft so that it makes a half-round hole in each. Then use a piece of drill rod or music wire the size of the hole and push it in. You might need a bit of loc-tite or super-glue to keep it in place, but maybe not if it is a press fit. Another option would be to tap the hole and use a screw. Maybe two at 180 degrees for balance.

Offline 90LX_Notch

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Re: Ultra Tiny (1/4 scale Tiny)
« Reply #43 on: February 04, 2017, 11:53:05 PM »
Thanks Carl.

Paul- The flywheel is steel and is only .047 wide, .156 od with a .020 bore.  The crankshaft is .020 dia.  If you can do a Dutchman on that you will be my hero. 
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Offline b.lindsey

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Re: Ultra Tiny (1/4 scale Tiny)
« Reply #44 on: February 05, 2017, 12:52:29 AM »
Put it down for a while Bob, take a deep breath, and then keep going. Its such a unique little engine it deserves to be finished and shown off. You will get it I am sure. I wouldn't even attempt it in that size.

Bill

 

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