# The Frank Wiggins "S.T." double acting oscillator of 1943



## Kaleb (Nov 11, 2011)

I've decided it's time to tackle building an engine from castings. So when this set came up on eBay, I thought it was just the thing to start with. Well, after waiting around 6 weeks, it finally showed up.





The designer's impression





The raw castings





A list of all the parts





A view of the cylinder dimensions on the plans. 7/16" (approx. 11.1mm) bore and stroke. 





Since the Jacob's chuck I have for my lathe can only take up to a 7mm drill, there won't be much room for a boring bar in there. So I bought this exquisite little Micro 100 from John Buckley. Paid a good $50, that's quality tooling for you!

This one should beep me busy for a good while, but hopefully it will be a little ripper of an engine if all goes to plan.


----------



## ShedBoy (Nov 11, 2011)

Nice little wobbler. Should keep you amused for a bit.
Brock


----------



## Kaleb (Nov 18, 2011)

Made a start over the last couple of days. I decided to tackle the cylinder first, since getting it right could make all the difference.





Facing the port face. This face also becomes the reference.





The cylinder after facing and filing the port face and one end.

The two end faces of the cylinder must be absolutely parallel. I decided that the easiest way to achieve this is to make a fixture called a wax chuck. These are commonly used by clock and watchmakers. Here's a rough sketch to show the basic principle:





The adhesive is traditionally wax, but shellac, loctite and superglue will also work fine. Here's a walk-through of using one to make a part for a clock: http://www.snclocks.com/TechnicalInformation/Tid-Bits/Tid-Bit-2-Using-a-wax-chuck/4174805_W9qLsx#243895865_h4LDZ

I'll post some more details of making a wax chuck in a seperate thread. My next post in this build thread will show the results.


----------



## lazylathe (Nov 18, 2011)

I also bought this same kit of ebay a few months ago!
It has been sitting in the drawer since and now i will be able to see what the correct
sequence should be!

Will be following along with you!

Andrew


----------



## Kaleb (Nov 19, 2011)

Made the wax chuck yesterday, and it worked a treat.





The cylinder casting and wax chuck to the left





Both pieces solidly joined with superglue





All set up in the lathe





Facing the end of the cylinder





Facing done





The cylinder end face after filing





Heating with the blowtorch to part the glue





Workpiece off just before removing the remaining glue

Checked the end faces and they are pretty much spot on parallel, so the wax chuck has worked perfectly.


----------



## smfr (Nov 19, 2011)

Nice! Will mentally file away the glue chuck technique for later!

Simon


----------



## Kaleb (Nov 20, 2011)

Okay, with the ends of the cylinder faced parallel, it's time to bore it.

First, the bore centre must be found. I used a method suggested by John Buckley to locate it.





First one of the end faces is covered with ink. I don't have any of the special marking ink that others in the game use, so I used a black texta instead.





Next, the dividers are used to scribe a series of arcs across the surface. This is repeated at least 4 times, until all of them meet at a single point in the centre.





First arc scribed





The centre has been located and marked with a centre punch, and a circle has been scribed to roughly show the profile of the bore.





Now the cylinder is set up in the 4 jaw chuck with a piece of thin plywood to protect the port face. The jaws are adjusted until the centre mark is running true.





Centre drilling the cylinder.





Drilling a 7mm hole right through.





Boring the cylinder to diameter.





Done. I ended up with a bore of about 11.7mm, which is slightly more than what the plans called for, but it shouldn't matter too much. I'll simply make my piston bigger.

The cylinder will be put aside for the moment while I set about getting a tap and die of a suitable size for the cap screws. The plans call for a 1-72 UNF thread, but I'll probably use a metric one. M2x0.45mm is very close, but I might go smaller to be sure, maybe an M1.6 or something like that.


----------



## steamer (Nov 20, 2011)

Hey Kaleb,

Getting everything square and parallel is never easy. It usually drives you nuts and can be very frustrating.

A technique to keep in mind while doing parts like this is to reduce the number of set ups.  In saying that I mean, do as many operations on a part as you can in one chucking. It is "nearly" inpossible to set up on a surface twice , and although it can be done, it is made damn near impossible with very small parts.

For instance, do the bottom face and bore of the cylinder in one chucking because squareness there is very important to an engine.  Then flip the part and face the top surface as parallelism of the top cover to the bottom, on a steam engine, is not that critical.

Now, there are other ways to skin the cat.  You can bore the cylinder, and then mount it on a close fitting arbor and while so mounted, face both cylinder head faces parallel to eachother and, depending on how well you made the arbor, square to the bore.

Sometimes the error is very small, and to correct it only takes a .001-.002" of stock...but it helps later when you assembling the engine.

Just and observation and a albiet unsolicited piece of advice from the part of my brain that I've beat against the wall far too many times while trying to deal with small parts.  File it away for the next part.

Looking good!

Dave


----------



## Kaleb (Nov 22, 2011)

With the cylinder only needing a few more things done to it, I made a start on the frame casting a couple of days ago.





Cutting off the base of the sprue with the hacksaw.





The whole casting is then set up in the 4 jaw chuck like so.





Facing the bottom.





The resulting surface before finishing with a file. This surface also becomes the reference on this casting.

To face the top of the frame, I decided to use my shop made wax chuck again to make sure the two surfaces come out parallel.





Workpiece attached with superglue. This stuff really lives up to its name!





Set up in the lathe.





Facing the top of the frame.





Top surface faced and ready for finishing with the file.





While I was at it, I decided to file off some of the flash on the sides.

I paid a visit to a local optometrist to see if I could get some small taps, but he's willing to tap the holes for me if I bring the cylinder in. A very nice gesture, and it also means I don't need to buy any for the moment.

Next, I'll probably make and lap the piston and piston rod and lap the cylinder.


----------



## steamboatmodel (Nov 23, 2011)

"I paid a visit to a local optometrist to see if I could get some small taps, but he's willing to tap the holes for me if I bring the cylinder in. A very nice gesture, and it also means I don't need to buy any for the moment."
What size taps are you looking for? The Optical repair kit I have has two taps 45/90 and 52/90 both of which are way smaller than anything I have used on a steam engine.
Regards,
Gerald.


----------



## Kaleb (Nov 23, 2011)

steamboatmodel  said:
			
		

> "I paid a visit to a local optometrist to see if I could get some small taps, but he's willing to tap the holes for me if I bring the cylinder in. A very nice gesture, and it also means I don't need to buy any for the moment."
> What size taps are you looking for? The Optical repair kit I have has two taps 45/90 and 52/90 both of which are way smaller than anything I have used on a steam engine.
> Regards,
> Gerald.



The plans call for 1-72 UNF which has a major diameter of about 1.8mm.


----------



## steamboatmodel (Nov 24, 2011)

OK that is a large thread for a optometrist, but small for the rest of us. I think I have one that size somewhere, but if I was doing it I would want two of them on hand. I found them listed http://www.fastenal.com/web/products/detail.ex?sku=7002215&ucst=t at Sale Price: $5.537 if you need to buy some. best of luck.
Regards,
Gerald.


----------



## rhankey (Nov 25, 2011)

Where does it call for a 1-72UNF thread?

I made a couple modern ST oscillators earlier this summer which have pretty much identical dimensions in all the key areas as the old one you are building. the main difference is the standard and cylinder castings are shaped slightly differently. I just checked the plans, and the only threads it called for are 7BA, 5BA and 1/4x32TPI. The only one that got a little dicey was threading the hole in the face side of the cylinder for the stud on which the cylinder pivots, as there is not a lot of depth to work with. I cant imagine where a 72TPI thread would be desirable on this model.


----------



## Kaleb (Nov 25, 2011)

The 1-72 UNF thread is called for to fix the cylinder caps on.


----------



## rhankey (Nov 28, 2011)

Sorry for the delay in responding. If it helps, the modern S.T. Oscillators specify 7BA for the three studs/nuts that attach the top and bottom cylinder caps. I was able to get an airtight seal without using a gasket or reefing down on the nuts. 7BA works out to 52.91TPI which seemed plenty fine enough for the purpose. In planning ahead, you might want to look at the what is specified for the stud that the cylinder pivots on. The modern oscillator specifies 7BA for that too, but you need a very carefully bottom tap it so you don't end up with an unplanned hole in the side of the cylinder - and even then, you don't end up with a whole lot of threads.


----------



## rleete (Nov 28, 2011)

Kaleb, where are you located? If you're in the US, I could send you some .010" teflon sheet for gasketing.


----------



## Kaleb (Jan 17, 2012)

About time for an update on this project. I tried making a template for drilling the end cap screw holes, but was having all sorts of trouble. I left it for many months, but I now have a vertical slide for my Sieg lathe, which I used to drill the holes spot on.





The cylinder with its top end cap and screws. I ended up using an M2 thread for these, tapped into a 1.5mm hole. The end cap was a fairly simple turning job done on the Hercus, since I wanted to keep the Sieg set up with the milling attachment. The screws shown here were salvaged from an old floppy drive that was just kicking around gathering dust.






The end cap screwed in place on the cylinder. I've decided to make gaskets for both end caps from automotive gasket paper.


----------



## steamer (Jan 18, 2012)

Looking good Kaleb!  :bow:

Dave


----------



## bearcar1 (Jan 18, 2012)

Things seem to be progressing well on your build Kaleb. If you do not have automotive gasket material already, an alternative is to use an old brown paper bag from the grocery store carry out. After cutting out and making holes, a light soaking with some sewing machine oil and a pat dry with a paper towel will yield a very useable gasket and at a fraction the cost of commercial gasket sheeting. Of course there is always teflon which is even better if you happen to have any about the shop.

BC1
Jim


----------



## Kaleb (Jan 18, 2012)

Got the bottom end cap done today. Another fairly simple turning job. The thread has come out slightly wonky, but it should be fine since the hole is true.





Here it is mounted with the piston inside.





Another view from the side.

It's coming along well now, just need to file back the protruding edges of the caps, make the gland nut, do a bit more lapping, make and attach the trunnion, drill the porting and the cylinder will be done.


----------



## fcheslop (Jan 19, 2012)

Hi Kaleb,nice job you are doing on this engine but I think that wobbly thread may cause a little binding on assembly.
best wishes frazer


----------



## Kaleb (Jan 19, 2012)

You're right, it could bind a little bit, but I'll sort that problem out when it comes.


----------



## Kaleb (Jan 24, 2012)

Here's some more work I've done over the last few days:

I decided to mill the sides of the base to make it easier to hold for drilling.





The base is clamped in the quick vice like so with a 4mm end mill in the lathe chuck.





Milling one side. All sides were milled without removing the job from the vice.





I decided to use an end mill for drilling the mounting holes since it does not wander. Sorry about the blurry photo, but my camera was refusing to play ball.





The base is then turned around to square the end of the piece which the crankshaft will run in. It is held in place with a G-clamp since the vice would not open far enough. I used a 12mm end mill this time to cover the whole area in each pass.





Milling underway. I did this operation in several light cuts.





The vertical slide is moved down to mill the area behind the port face. It is done in the same way as the last operation.





The workpiece is then turned around to mill the area on the other side from where the first operation was carried out. That's a toolmaker's style clamp I made in high school metalwork class. Knew I'd find it handy someday.





The port face itself was filed smooth as recommended by Stan Bray in his book covering the construction of several different oscillating engines.





The base is now finished except for the trunnion hole, porting and a bit of lapping.





I then turned my attention back to the cylinder. The plans call for the trunnion to be held to the cylinder by a screw thread. To ensure the hole is exactly where I want it, I start with a centre drill. I had previously marked out the port face to assist in the set up.





Starting the hole.





There's not much metal between the port face and the cylinder bore, so I wanted to be sure I didn't go right through. I used a ruler to make a mark on the drill bit with a texta so I knew exactly when to stop. If you look closely, you should see the mark.





To be doubly sure, I moved the drill back into the chuck to the mark so it can't go any deeper.





Drilling the hole to depth.





I then clamped an M3x0.5 tap in the chuck and turned it by hand, but I needed the thread to go right to the bottom of the hole.





The tap towards the top is a regular intermediate tap. This is fine for most jobs except where the thread must go to the bottom of a hole. The tap beside it is a bottoming or plug tap. It will cut a thread right to the bottom, but cannot start a thread like a taper or intermediate tap can. The bottoming tap was used to take the thread right to the bottom.

Here are a couple of photos taken while making the trunnion showing the collet chuck on my Hercus lathe.









The collet chuck really comes into its own when working with small diameters.





Here's how it looks so far. The black colouring on the cylinder is due to me needing to silver solder the trunnion in place and using waste oil to leave residue to prevent silver solder wetting where I didn't want it.


----------



## Kaleb (Feb 2, 2012)

I've made progress over the last week or two, and it's really coming together.

The trunnion of course needs a nut to tension the spring.





So I set up a piece of brass in the Hercus with the matching collet.





Facing the end of the stock.





Turning to size.





Centre drilling for the live centre.





Since I had made the 12mm (1/2") American toolpost, I decided to put a big J&S knurling tool that came with the Hercus into use. For this operation, I ran the lathe in the slowest back gear to reduce the strain placed on the tool.





Drilling a 2.5mm hole to take an M3x0.5 tap.





To tap my threads straight, I grip the job in the lathe, and grip the tap in the Jacobs chuck, and turn the Jacobs chuck by hand.





The workpiece was then transferred to the Sieg lathe and faced.





Finally, the nut is parted off.





Here it is in place with a spring wound from some thin music wire.





Next came the big end. I started by facing another piece of brass rod. I did it in the Sieg lathe this time since the Hercus was having some belt trouble.





Centre drilling the end.





Turning a length down to diameter.





Parting off.





Drilling a 2mm hole to take an M2.5x0.45 tap.





Tapping the hole.





Turning the shoulder.





Parting the piece off.





To drill the hole for the crankpin, the big end was set up in the 4-jaw chuck and flattened on one side with a 3mm end mill.





A centre drill was then used to start the hole.





Drilling the hole to 1/8" right through.





The finished big end in place on the engine.





The crankshaft set up for drilling the web for the crankpin. The plans called for a 2-piece crankshaft made from cold rolled steel, but I have decided on a 3-piece design with a shaft made from stainless photocopier shaft and a brass web and pin.





Starting the hole with a centre drill.





Drilling the hole to 3/32".





Next came the crankpin. I made this from a bit of thin brass rod I found at the scrapyard one day. First the rod is centre drilled.





Turning the rod down to a bit under 1/8" as per the plans.





Parting off.





Now for the flywheel. The plans called for this to be made from cold rolled steel, but I decided to make mine from brass. The workpiece was firstly faced.





The hole through the hub was then started with a centre drill.





Then drilled to 4mm right through.





To do the rest of the machining operations, I decided to make a mandrel. First a piece of 6mm photocopier shaft is centre drilled.





Then turned down to 4mm and threaded M4x0.7 part way down.





The flywheel is secured to the finished mandrel with a pair of nuts.





Turning the outside of the flywheel.

That's all for now, but an update should be coming soon.


----------



## tel (Feb 2, 2012)

Coming along nicely Kaleb


----------



## lazylathe (Feb 2, 2012)

Nice work so far Kaleb!!

Just to go back to another thread everyone was talking about...
I see you part using a live center in the tailstock.
Any reason for this?
Has it caused you any trouble with the work piece getting caught?

Andrew


----------



## bearcar1 (Feb 2, 2012)

Good progress so far K'. I couldn't happen but to notice in one of your images that you left the chuck wrench in the chuck while you were doing something else. I hope you do not have that habit. Remove it and set it down on the bench each and EVERY time you will be taking your hands off of it, even for just a few moments. Forgive me if I sound harsh but seeing that made me want to scream.

BC1
Jim


----------



## Kaleb (Feb 2, 2012)

I always take that chuck key out before turning the lathe on.


----------



## Kaleb (Feb 28, 2012)

About time for an update on this engine.

Here are some more shots of the crankshaft being made:









To ensure the crankshaft runs freely, I decided to lap it to the bearing with toothpaste.









The next shots show the making of the crank web.

































Finished except for the crankpin.





A quick shot showing how I wound the spring.

Now, back to the stuff I haven't covered yet. 





Turning the flywheel down for a belt groove.





Machining a recess into one face.





The flywheel is then set up in the Sieg lathe's milling attachment to put a hole in for a grubscrew.





Starting the hole with a centre drill.





Drilling the required diameter.





The engine frame has two steam connections cast into it, which will need to be machined and threaded. So the whole frame casting is set up in the big Hercus lathe, and the tool set at an angle to clear the rest of the frame.





Machining the connection down to diameter to take an M6x1 thread.





Threading with a die by hand.









Facing the ends.





To machine the other connection, I clamped the 4-jaw chuck from the Sieg lathe in the Hercus by the recess which centres the chuck to its backplate, and then clamped the frame in it with one jaw removed for clearence.





Machining underway.





Both steam connections done. Please excuse the lens cap cord dangling in the shot.





When I was assembling the engine, I realised the crank web needed a grubscrew to hold it. So I set it up in the Sieg lathe to drill the hole.





Starting with a centre drill.





Drilling right through.





Tapping the hole.









Here's what the engine looks like now.(except the steam connections are not threaded in these shots.) All that's left to do is the porting and possibly a bit of lapping. I'm not sure how to do the ports in the cylinder. They need to be drilled at an angle so they will emerge right at the ends. As far as I know, these castings are no longer available, so I want to get it right.


----------



## steamer (Feb 28, 2012)

Great build thread Kaleb!  I'm looking forward to the first run!

Dave


----------



## fcheslop (Feb 28, 2012)

Hi Kaleb,try using a drill jig to do the ports I will see if iv got any pics
best wishes Frazer


----------



## fcheslop (Feb 28, 2012)

Hi again,the jig is made from a bit of scrap and drilled to the port layout for youre engine.Hope this is of some use
best wishes frazer


----------



## rhankey (Feb 28, 2012)

As with most machining operations, the reality isn't as difficult as you imagine it to be.

I made a couple of the current version of the Stuart oscillators last summer prior to getting my mill. I used a dremil drill mounted in a mini drill press table. I started each hole perpendicular to the face, going in perhaps 1/32" to create a little divvot. Then I very carefully clamped the cylinder in a machinist clamp at correct angle, and drilled the hole at the angle through to the cylinder using the pilot hole to prevent the drill bit from wandering. Both cylinders came out perfectly. As an alternative, you could make an angle block out of piece of scrap wood to help hold the cylinder at the correct angle. But either way, start the pilot holes perpendicular else the bit will likely wander.

The 4 port holss you had to drill in the base are a lot trickier. With the current the Stuart oscillators, there was very little margin for error, else you would end up with holes seeing daylight where they shouldn't or not connecting with cross holes where they should.

Robin


----------



## Kaleb (Mar 16, 2012)

Well, it's a runner. Yes, I have made a video, but first, some coverage of the final stages of the build.





To drill the ports in the cylinder, I cut a piece of wood on a mitre saw so the cylinder would be held at the correct angle when clamped.





The cylinder and angle block were then set up in the Sieg lathe with its milling attachment to start the holes.





Starting one of the ports with a centre drill.





The cylinder was then clamped in a larger machine vice and the ports drilled right through on my trusty(albeit rickety) drill press.





To make the porting jig, I decided to make a makeshift transfer punch out of some stainless steel shaft.





Machining the OD even.





Centre drilling to allow the workpiece to be supported by the tailstock.





Turning down to 2.5mm to match the ports. I am using a dead centre because it doesn't wobble as much.





Next, I set the compound slide to 10 degrees to machine a point.





Turning the taper until it forms a point.





Here it is finished except for an attempt to heat treat it which failed to make it any harder. That didn't matter too much since I was using it to mark soft metals like aluminium and the bronze of the castings(which I think may actually be gun metal since the finish after machining is a lot like brass.).





Finally comes the porting in the frame. I decided to start with the two holes that run vertically to carry steam or air to the ports themselves. So the frame was set up in the Sieg lathe with the milling attachment like so.





Once again, the holes are started with a centre drill to ensure they are in the right spot.





The centre drill is then replaced with a conventional 2.5mm drill bit to finish the hole.





Drilling the hole to depth.





Next were the holes through the threaded steam connections. I had to try a couple of different setups before I was happy to go ahead with this stage.









Drilling each of the connections in turn.





To drill the ports themselves, I made a porting jig from a piece of aluminium plate which I drilled with the correct layout in relation to the trunnion with a line scribed through the centre. The jig is moved so that the centre line points to the crankpin at mid-stroke. The punch was then used to mark the positions of these holes.





The frame was once again set up in the Sieg lathe and milling attachment to drill the ports. It took several attempts to get all the holes to actually meet, I had to solder up some that went through when they shouldn't, and I even got a drill bit in my finger at one stage! Nevertheless, I got there in the end.

And here's the video of the engine running on air:

http://www.flickr.com/photos/[email protected]/6839544032/

I tried to embed it, but I couldn't get it to work.


----------



## lazylathe (Mar 16, 2012)

Nice work Kaleb!!
Must feel great to have a runner!!

Are you going to shine it up or give it a lick of paint?

I am sure once you have run it in for a while it will be able to run nice and slowly.
Andrew


----------



## 90LX_Notch (Mar 16, 2012)

Kaleb-

Congratulations!  Thm:

-Bob


----------



## danstir (Mar 16, 2012)

Great job. Thanks for sharing your build.


----------



## b.lindsey (Mar 16, 2012)

Looks and runs great Kaleb. Thanks for sharing the build!!

Bill


----------

