Pip-squeak engine build

[mklotz]

Now that I know you have an RT, I can offer the following hint...

Trepanning a flywheel is, as you discovered, something of a PITA.  One way to simplify the job is to mount the flywheel to the RT and rough out the trepanned area with an endmill before putting it on the lathe and doing the finish work.

Boring bars are useful tools for working the "walls" of the trepanned volume.  If your chucks are not the screw-on type an upside-down boring bar and the lathe rotation reversed will allow you to work on the inner "wall" of the excavated volume.

[fumopuc]

Hi Todd, congratulations for this runner.

[Hugh Currin]

Very nice build. Thank you for documenting it.

Hugh

[arnoldb]

Well done Todd 

  ...  The ports shouldn't get exposed like that for a wobbler, but it runs and the inlet port getting exposed and blowing by makes it sound nice  .

I do have another concern though, and unfortunately only noticed it now...  It appears that the whistle hole is on the inlet port side of the engine column rather than the exhaust side.  That means it will just continually whistle and require even more air to run once you fit the whistle.  Is it possible that you can post an image taken from the plans showing the top of the column ?

Kind regards, Arnold

[tinglett]

Thanks everyone for the kind words!  It is really nice when things work out, more or less

Marv, thanks for the tips using the RT and it gives me a little hope the flywheel work wasn't just me.  I didn't think at all about boring bars.  I'll try that.  I did like running the lathe in reverse for some of the "inside" work.  It was lots easier to see what was going on.

Arnold, I was also worried about the squeaker running on the inlet air.  Here's this part of the plan.  I can try running it in reverse by swapping the inlet/outlets, too, since this engine is so simple.


I was thinking the squeaker might get louder when the engine wasn't consuming air, but I wasn't expecting exposed ports.  The port position does make a nice "chuff" though, so maybe it's not so bad .

Todd

[Don1966]

Todd the whistle will squeak as the cylinder oscillates. The pressure pulsates as the cylinder moves back a forth. The sleeve that fits over the whistle controls how much air moves through it.

Don

[tinglett]

I had time to make the squeaker this afternoon.  Here's how it went.

I faced and turned a length of 5/16 inch hex stock.  It calls for the end to be rounded over.  I decided to do this cheaply with a few angle cuts starting with a 45 shown here.


A few angles are done:


A small amount of filing and it looks pretty good.


I flipped it around, turned and cut some threads, and proceeded to drill out 3/16 inch inside as indicated by the plan.


I removed the squeaker from the chuck, and then chucked a smaller diameter brass rod scrap and turned it down to fit the hole in the squeaker.  Here I'm doing a test fit with the lathe powered off.


This internal rod needs to have a flat that will form the whistle.   Here I am milling off 50 thousands as called for by the plan.  After some tests with the squeaker later in the day, I re-did this part with only 30 thousands removed and it worked better due to less air loss.   I had trouble clamping this piece as one parallel in my set was too low and the next size too high.  So I sandwiched a thin rod underneath the parallel -- in case you were wondering what that was all about.  It worked pretty good.


Here's the version I made with 50 thousandths removed.  Getting pretty close to the vise!


Next was time to cut a 45 degree notch in the squeaker.  It's a typical looking whistle, which is more obvious in later pictures.  Here I have it in my bench vise, actually a tiny vise clamped in a big vise, and I put a few washers on as spacers to keep my work straight.  I started with a hacksaw cut shown here.


I filed the 45 degree part with a needle file and it came out pretty good.  I realized the threads got gnawed down a bit because I hadn't finished taping the hole in the upright with a bottom tap. I don't happen to have one for this size .  Oh well, I doubt it will hurt.


The flattened insert goes in and makes it whistle when you blow on it.  The right position really was even with the flat part of the opening, so here I am milling the insert to length.  By the way, the fit of this insert wasn't perfect.  I actually made three versions of it, and it went from not being able to fit at all, to being too loose.  But one light whack of a hammer fixed that   I actually realized I could do this when I found the burr from milling it made it fit too tight again.


I tried the whistle before moving on.  I'll post some video with it.  My daughter thinks it sounds a bit like a dentist's drill.  It's way too high pitch, so I'll probably run it with the cover down.  Speaking of the cover, I started making it here.  I was planning to hit the home center for some hobby brass tubing but found they don't sell it any more.  Rather than drive all over town, I decided to make the little guy.  I started with some 3/8 inch brass rod.  Here I am starting to drill it.


I started with a 1/4 inch drill and continued up until I got to 5/16 inch (the size of the squeaker).  I was hoping to stop at "N" which was slightly smaller...but it was still too small.  Unfortunately, 5/16 was too big, so I squeezed the part slightly in my vise to distort it so it would "stick" in an up or down position on the squeaker.  The idea is that it can optionally cover up the whistle hole.


Here is a close-up of the squeaker with the cover lifted.  I probably won't leave it lifted much.


And here is the "finished" engine.  I'll leave that in quotes because I have a lot of cleanup and tweaking to do.


The engine is also supposed to be "blued."  I have some of the stuff, but have never used it.  I'll practice on some scrap and see if I like what I get.  The bare steal and brass look pretty spiffy, too.

Todd

[tinglett]

Here's a video. It's really hard to hear the squeaker whistle.  It's running much slower and the "chuff" is the good part

[youtube1]http://youtu.be/1wC0nc_V5G0[/youtube1]

Todd

[tinglett]

At the risk of being kicked off the forum, today's pip-squeak installment involves woodworking!

I thought I should take time to mount it to a nice base so I don't scratch up the engine mounting it to the base later on.  I had already made a set of six bases when I built my first engine, because it's lots easier to make six bases at once than six bases one by one.  How's that for an optimist?    The bases are all 5x6 inches so they can only accommodate little engines, and here we have a little engine.

Here's a photo of the engine resting where I want it on the base.  I'm leaving room for a name tag at the front which is represented by a little slip of paper.  Perhaps after this engine I'll order up some brass name tags for the 3 engines I have constructed so far.


I laid out the points for the 4 mounting holes, marked then with an awl, and used the drill press with a 3/16 inch brad point bit.   I really missed the accuracy of the mill when doing this, but I didn't want to blow wood dust all over it.  These holes were pretty tight for the #10 machine screws.  It turns out I did have to slightly elongate the hole that's under the bit in this picture.


There are four machine screw heads sticking out the bottom of the engine.  You may have noticed that the engine is floating above the wood base in the first photo due to this.  I want the engine to rest flat on the wood base, so I needed to drill some clearance holes.   I screwed the engine down tightly and removed it, and it neatly left marks where these clearance holes need to be as can be seen in this picture.  Of course I knew the measurements, too, but this was easier.


I drilled the clearance holes with a 1/2 inch forstner bit.  A smaller hole would have worked, but I didn't want to mess around making things line up since I was eyeballing these.   A regular bit would have been a little more messy, but would have worked fine as these are completely covered up by the engine.


I test fitted the engine, calculated how much clearance I needed for those machine screws, and drilled similar clearance holes on the underside.


Then I screwed down the engine.  Here's what it looked like underneath.  While nobody will normally see this angle, I still wanted it nice and tidy.


And here it is, looking nice and presentable!


Now I need to disassemble and polish up the engine.  I also need to look into the bluing process and see if I dare do that to it.  I'll try some test steel first.

Thanks for checking in!

Todd

[Don1966]

That's looking good Todd and nothing wrong in doing a little brown work for a great project. Are you going to put a bevel on the engine base as well? By the way I did blue mine with gun bluing.

Don

[b.lindsey]

Todd, both the whistle and the base look terrific. Nothing wrong with a little "brown" stuff work for bases and such. I find it kind of a nice break at times. SO what do you have planned for engine #4?

Bill

[tinglett]

Don,

I have put some thought into a bevel for the steel base, but I already have that on the wood base so I was finally thinking against it.  For a while I also thought about a rabbet around the edge, but it looks pretty good as-is.  That is, I don't really need to make it appear thinner.

I do want to blue it, so I'll play around with that a little this weekend.  I have a bottle of Birchwood Perma Blue that's newly purchased.  Any tips?  From what I've seen on the web, it sounds like I should work fast.  That is, wipe down in < 30 seconds.  How much do I need to worry about surface prep -- both polishing and cleaning?  If it works like wood stain I need a very even polish, but (hopefully) it doesn't.

Did the squeaker on yours work very well?  I'm not very happy with how mine sounds, but appearance is ok.  I really like the chuff, chuff sound without it.  Can't beat that

Todd

[tinglett]

Bill,

Oh yeah...the next engine!  I have indeed been thinking about that .   As I started this one, I noticed another oscillator on the board that I liked.  It's the one from Steves-workshop.co.uk.  Very nice, but I've already got 3 oscillators (almost) done.

However, about a month ago I was browsing through the Plans And Drawings section of this forum and ran across Stew's (sbwhart) Potty Mill Engine.  Julius make some excellent drawings that I believe I can follow.  I think that's the one.

BUT...I need to control myself and do a tiny bit of shop cleanup and some machine tuning before I move on.  I need to practice grinding some cutters as well, or I'll be limping along forever with these purchased carbide things.  They are ok, but completely non-adjustable (so to speak) as you know.

Well, we'll see how long that control lasts.  This is WAY too much fun

Todd

[b.lindsey]

Good choice on the next engine Todd. Yeah it is fun isn't it !  Just wish I had more time at the moment to devote to hobby pursuits rather than work but such is life 

Bill

[b.lindsey]

P.S. I am also interested in how the blueing works out for you so I hope you will document the process which I hope works out well for you and this nice project.

Bill