Pip-squeak engine build

[tinglett]

I'll take the plunge and do a build log of an easy engine.  It won't be nearly as exciting as the big stuff I see here, but I'm hoping to get plenty of criticism and advice -- hopefully in a positive way.  I plan to post loads of photos, so please let me know if I'm overdoing it.  I've shrunk them down and I'll use clickable (zoomable) thumbnails for most so hopefully the photos won't get annoying.  I lurked quite a bit here before finally getting off the ground, and I'm hoping this helps others who are doing the same.

Ok...so the engine.  It's a simple oscillator that is made primarily of cold-rolled steel.  My first two engines were also oscillators, but were mainly aluminum.  This one is called the pip-squeak that's from a plan by Bill Reichart available from Little Machine Shop https://littlemachineshop.com/products/product_view.php?ProductID=2343.   Note that there is more than one engine floating around with this name.

Here's the image of the engine from little machine shop.  Hopefully I'm not violating rules showing it direct.  I'll link it to their website if you want a closer look.


The engine has two supports that form the frame.  The tall one will support the cylinder and is 1.5 inches wide, almost 4 inches tall, and 3/8 inches thick to give an idea of the engine size (~3.8cm x 10cm x 1cm).

Here I square up the tall and short supports.



Next I had to drill and ream what will become the bearings for the shaft.  These need to be perfectly aligned so the plan advised to do this together.  I hadn't milled the sides of the supports, but they were cut from the same bar and were reasonably straight so I used paper to get a tight fit in the vise.  I'd be interested if anyone has opinions on how this should have been done.



I did a little countersink before reaming.  I've found this makes it easier and I figure it wouldn't hurt as it needed some deburring anyway.





The plan suggested I align the holes perfectly with a pin and do one last trimming pass on the base to make sure they are perfectly aligned.  This was an excuse for me to do simple turning on the lathe anyway.  The pin came out nice and snug.



Here's a closeup in case you spot something odd.  The process seemed to work good.



I'm a little bit further so I'll post more in a bit, but I figure this is enough for the first post on this one.  Thanks for looking!

Todd

(Update: replace PB photos)

[b.lindsey]

That's a nice little engine Todd and one that is pretty well know as are many of his designs. You are off to a great start and I am sure it will help many seeing your build log. I will be following along myself.

Bill

[Don1966]

Todd I will be following along also. That was my first engine built in 2010 and it's a great engine to get started with. I have built two of Bill's engine.  Enjoy it because your off to a great hobby. Looking forward to your progress and it looks like your have a great start.

 
Don

[Jo]

Hi Todd. Linking to pictures on other sites is fair game as we are not copying them

I like the use of the dowel for alignment. Do you need to turn then on to their sides to give them a quick skim? Are you going to use a clamp on the end to turn. One trick I often use is to dab some superglue  between parts to give them that little extra encouragement to keep in line 

Jo

[tinglett]

Don, very cool to hear you've built this one!   Now I know I can't get stuck .

Jo, I avoided skimming the sides because there is lots of shaping yet to do.  Only the last bit near the bottom (0.25 inch) remains at full width.  This dimension is certainly not critical, but I decided to save as much material as I could.  It would be interesting if skimming them would eliminate the need for paper in the vise.

In general I decided I should try to make all parts as exact as I can, even though many dimensions are clearly non-critical.  That'll give me extra practice that I desperately need .   I don't have any formal training and only have books, the web, and this forum to get me through it.  So far it's fun, and that's 100% of why I'm in it.

BTW, I should have mentioned that I have Little Machine Shop's HiTorque mini mill (part #3990) which, if I am following correctly, is a variation of the Seig X2.  So far my only real complaint is the amount of backlash in the lead screws.  I found some errata at the LMS web site on how to adjust this.  Adjusting helped a lot, but it still has ~5 thousanths in both X and Y, and the backlash is often very hard to feel so it drives me nuts.  Z is much worse and I've given up on it.  I keep a dial indicator set vertically and use it for Z.  You can see this in the background of the photos.  That works incredibly well.

I also have a Harbor Freight 7x12 lathe (item #93799).  That's had a zillion adjustments made to it, and I feel like I'm only 1/4 done setting it up .  But the lathe and mill were cheap, so I can't complain much.  I wasn't sure I would really get into this as a hobby when they were purchased, so I was very conservative.  It actually took me a couple years before I got a real start.  That's partly because tooling is the real cost.  I know that now .

Todd

[mklotz]

Everything you've done looks just fine but let me offer up another approach to think about and perhaps expand your horizons.

Finish the bottoms of the two standards and drill and tap them with the holes that will be used to secure them to the finished base.  Now bolt them to a piece of sturdy scrap in such a way that they are right next to each other.  Mill the sides to spec, cutting into the scrap piece if necessary.

Now you can drill the shaft hole and be sure that it will align in the finished model.  In addition, the profiling on the sides will be identical on both pieces, not that that is critical.

As I said, I'm not suggesting that this is the way you should have done it.  It's merely a different approach to stretch your thinking.

[tinglett]

Marv,

Thanks for the perspective.  I'm a little ahead of the photos (will post more in a minute) and I just finished some of the shaping of the uprights.  This idea would have helped me shape the pair together.  They are common at the very bottom...but I suppose the plate would be partially in the way for that.  I'll think about that considering I can cut into the scrap plate so long as enough material can hold it all together.  It may have worked.  And of course it would work for aligning the holes for the shaft.

Todd

[tinglett]

The tall upright has inlet on the left, exhaust on the right, and an interesting escape hole to the top.  It's an oscillator, so it has holes halfway through on the flat side to form passages as the valve mechanism.  The holes and the edges are tapped for fittings.   The escape hole to the top connects to the inlet and goes to a little whistle that will make the "squeak" as it runs.   I suppose it will squeak and use a little inlet air when the cylinder is exhausting.

Here's pics of drilling and tapping all those holes.  Nothing exciting other than the "squeak" hole was mighty high up for my little mill.  I was able to use a starter drill in my chuck, and then switched to a collet holding a #3 drill bit.  I don't have a collet for that size, of course, so I wrapped the bit in paper and pushed my luck .  Thankfully the starter drill took care of 90% of the hole otherwise I'm sure this would have failed.  I didn't get pictures of this precarious operation but I was careful and slow and ready for a mess.

I am thinking that it might be handy to make maybe 5 "mini" collets of some size that fit into a 3/8" collet to hold a few of these bit sizes (#3, #21, etc).  I've paged through Enco's catalog looking for something like it.  It seems a waste to have full size ones for this, but that's certainly an option, too.





On the inlet side I tested a little air fitting from Little Machine Shop.   I made a 10-32 thread instead of 1/4-28 for this one.


Here are the holes that form the valve mechanism for the oscillator.  They only go deep enough to join the passages I already drilled.  You can see here that I'm using my dial indicator to get the depth right.  I don't trust the micro-adjust on my mill.


Finally I drilled/tapped holes for mounting to a base plate.  Like Marv suggested, I could have made these early on and used for holding the parts temporarily together.





There we go...the two uprights.  But they are not done yet!  The plan provides options for making them simple or fancy.  I could leave as-is, or I could trim the corners with 45 degree angles.  Or I could get fancy.  I'm taking the fancy route.  I already got a good start on that, so I'll post those pictures in a bit.



Thanks for following along!

Todd

(Update: replace PB photos)

[mklotz]

I'm presuming you "wrapped the bit in paper and pushed my luck" because you didn't have enough head room on your mill to use the drill chuck.  Not only is that a good way to be inaccurate, it could become dangerous in a hurry.  Try this...

Make a flanged bushing that fits into one of your existing collets.  The flange prevents it from sliding completely into the collet.  Drill this out on the lathe with the drill you wish to hold.  Using a slitting saw in your mill, put three equally spaced slots into the bushing so the collet can clamp it closed on the drill.  Debur and mark the size on it.  When done using it, throw it into a box in your tool chest along with others for the drill sizes you use most often.

[tinglett]

Marv,

Cool...that's exactly what I was thinking I'd try to make.   I was indeed very worried that I'd end up with drill bit pieces all over the place.  I really only opened up the hole a bit, but I was thinking it was mighty stupid when I was in the middle of drilling like that.

I also could have slid the vise aside and clamped the upright vertically to the X table to get the clearance I needed.  That would probably have been the right thing to do until I had proper tools made.

Todd

[mklotz]

... I was thinking it was mighty stupid when I was in the middle of drilling like that.

Most of us have learned to stop immediately when we get that sort of nagging feeling about a setup or something we're doing.  It's your brain trying to protect you from harm.  Learn to not ignore such signals because the consequences of doing so can often be painful.

[tinglett]

Fancy Uprights

As I mentioned before, the next step is to make the uprights "fancy."   The plan showed some angles, all of which are (thankfully) 45 degrees.  None of these were marked, but the plan was created as full scale, so I did some measuring and gave them specific positions.  I used dye on the uprights and made lots of criss-cross marks to show where these really start and end.  I wasn't surprised to find most were on nice round boundaries (e.g. 1 inch), so I think I got it right.  It's all for looks, so none of these really matter.

Here's a photo of my layout work.  It wasn't as messy as it looks.  You can see some plan in the background for an idea what I'm about to carve up.


I started with the small upright and hogged out the majority of the space in at the bottom with a larger end mill, then switched to my smallest end mill (3/16th inch) and squared up the insides.  The other cuts are 45 degree angles.  I found a better way to do this with the tall upright, btw.







Next I needed to setup for the 45 degree angles.  I have never done this before so I needed to get creative in setting the vise at 45 degrees.  Remember I am trying to artificially use more precision than I need for practice.   Here is the crazy setup I came up with.  The 1-2-3 block can be squared and this will set the vise at 45.   I was worried about the clamp, but it held it plenty firm enough.  I couldn't flex it without significant pressure and the dial test indicator didn't push enough to cause trouble.  The toughest part was finding the base for my vise!  Seriously, I had never used it before   I also had never mounted the dial test indicator this way before. I was scratching my head and realized it had a dovetail on the front.  Cool.



I initially picked a starting point by touching the point of my edge finder to the corner of the upright.  Later I realized, duh, that I could use the center of the pin I made for the holes.  I spent a bunch of time doing the math to figure out how to move to the right starting position.  This involved a lot of multiplying or dividing by square-root-of-2.  But remember I mounted the work at 45 degrees, so the cuts were straight down X or Y.

Here's photos of cutting out the base.  I found the 3/16" end mill would flex, but later I found my Z gib had play that needed to be tightened out.  This was the main cause of the wavy finish and meant more filing than I would like...but it did eventually clean up.













Here's the small upright with all the 45 degree angles cut.  I thought it best to make slots so there would be plenty of straight material to hold the part while cutting.  Later I will place it on edge and do the final straight cuts.


Next is the tall upright.  It's pretty much the same operations, but I have exciting photos that I'm sure you can't wait to see....

Todd

(Update: replace PB photos)

[Don1966]

Coming together nicely Todd and your making good progress. I chose to make mine round on the bottom and top. .....................


 

Don

[tinglett]

Fancy Tall Upright

Here is the tall upright which is similar to the short one, but with a few extra cuts.  I was getting better at it by this point .

I got my bearings with the center of the shaft using the alignment pin I made earlier.


Then it was a matter of locating.  In this picture I had first calculated my X,Y to the point that just up and to the right of the end mill.  Remember that my vice is mounted at 45 degrees so the sloped lines are really along the X axis.  I was using a 3/16" end mill, so I had to slide it that far to the left.


Then I plunged in via Y, turned left via X, pulled back via Y and finished out to the right via X.









It's too bad I hadn't done the small upright this way because I really like the curvy look it produced.  With the small upright I had already made the straight cuts.  I guess I could have one part each way, but I'll probably trim this one to match.  Note the edge is still a little wavy.  I hadn't figured out that the Z axis gib was a little sloppy yet.  I've developed a habit of clamping down the Z axis lock when I take cuts and eventually I noticed that the head shifted a tiny bit.  That's when I realized the gib wasn't tight.


Then it was a matter of calculating and making the other cuts.  My math didn't always come out perfect.  Sometimes I'd forget to account for radius or diameter of the mill.  But I'd give it a close look before slicing into the part.  And I'd write down my settings relative to the center pin so both sides would be identical even if my math was a bit off.


Here I have all cuts done except for the slopes at the top of the upright -- which is at the bottom left in the picture.


Here I noticed trouble.  My calculated positions for the 45 degree cut on the top of the upright would dig into the spot where the squeaker will go.  Since these were easy 45 degree cuts on the outside, I simply moved it out one turn of the dial which is 1/16th inch on my mill.  Good enough.  I made the other side match of course.


And there's the tall upright with all the 45's cut.


Finally, I needed to make the remaining straight cuts with the vice back square with the mill.  I bought this spiffy roughing end mill for this purpose and I found it worked way better than I thought.  I could easily gnaw off 1/32 inch per pass (half a dial turn) on my mini mill.  That was fast enough for me.


And that's where it sits on my mill right now.  Work is getting in the way again (doh!) so these postings will slow way down for the holiday weekend here in the US.  My plan is to switch to my regular mill and trim the current cut to the size in the plan.  I can use the full height foot of the part that remains for an easy zero measurement (or I could read up from the parallels).  I'll flip over onto the newly flattened side and trim the other side in a similar manner.  That's the plan and I'll let you know how it goes.

Todd

(Update: replace PB photos)

[tinglett]

Don,

You rounded yours?  Was that done on a rotary table?  That's something that's on my list, but isn't yet sitting in my shop .

Todd