Bolton No.2 Mill Engine

[Jacob P.]

Great progress! Once I get more experience with machining, I’m going to tackle a PM Research No. 5 vertical steam engine build. I have the castings and have been brainstorming how to go about the machining. I’m very much a beginner, and these photos will be useful in guiding me how to go about it. Keep up the good work! Looking forward to seeing the finished product.

 

[jcreasey]

Great progress! Once I get more experience with machining, I’m going to tackle a PM Research No. 5 vertical steam engine build. I have the castings and have been brainstorming how to go about the machining. I’m very much a beginner, and these photos will be useful in guiding me how to go about it. Keep up the good work! Looking forward to seeing the finished product.

If you are a bit nervous making an engine from castings it's a good idea to try making an engine from bar stock first. Those are great because if you make a mistake you can easily replace any part. There are a lot of wonderful designs by Elmer Verburg for which plans are freely available.

Good luck with it in any case!

 

[bobden72]

Looking good

 

[petep]

What an amazing build. Thanks for sharing it with us. You make it look so easy - I'm half way through building the Bolton No 7 & have found it more difficult than I originally thought using castings. Your photo's are brilliant too. Maybe you could give us a few tips on how you get such good photos. Thanks again. Cheers Pete

 

[jcreasey]

What an amazing build. Thanks for sharing it with us. You make it look so easy - I'm half way through building the Bolton No 7 & have found it more difficult than I originally thought using castings. Your photo's are brilliant too. Maybe you could give us a few tips on how you get such good photos. Thanks again. Cheers Pete

Thanks Pete!
I take all of my photos with my iphone. It's a fairly recent one I think about a year old. I think it's important to make sure the lens is clean. I often retake a photo after cleaning some schmutz off of my lens. Also I think it's a good idea to have plenty of light but to avoid a single point source of light that produces hard shadows. Also I like to zoom in a bit so everything is nice and big.

Good luck with your engine. It's definitely a challenge building from castings! Mine is even trickier because the castings I have are version 1 and the prints are the revised version. I'm finding the differences as I go which is an added challenge.

Some more photos coming soon as I did a bunch more on the weekend.

 

[jcreasey]

This instalment covers my initial work on making the crankshaft. At the moment it is still a round disk but I am planning to make it a bit more interesting shape in due course. Once again the castings were a bit meagre for this part so I sliced off half an inch of bronze bar I had sitting on the shelf.

First step was to face it and drill and tap the center. This was supposed to be 1/4 40 but I went down to 3/16 - 40 so that I would have a nice firm boss for the flywheel to but up against.

I didn't take any photos but the next step was to put a thread on the end of the crankshaft.
I just single pointed that as I wanted to do everything possible to get things concentric.

Once that was done I screwed the two parts together and mounted them between centers.
I didn't bother with a dog as there was enough friction to drive things as I was taking nice light cuts with a very sharp tool.
This let me clean up the crankshaft part ensuring it was as concentic as possible to the main shaft.

Turning between centers makes it very easy to flip things over to finish the other side.
Not much room for a dog here so it was lucky I could get by with just friction.
Lots of stickout on this tool but it was very sharp and still cut ok.
I still use the faceplate just to make sure my spindle nose is protected.

Now that everything is concentric and parallel I detached the shaft again and setup in the mill using some parallels and a little V block so that I could drill and tap the hole for the crank.

That's about it for the crankshaft disk. Later on I will need to reduce it's thickness and diameter but I am waiting till a few more parts are done so that I can figure out where everything goes. A lot of stuff is coming together around the cross head and it is all quite interdependant.

 

[jcreasey]

Next task was the con-rod. This started out as a little gunmetal casting which I cleaned up in the mill.

Once I had things nice and flat I drilled the two required holes. The plan called for 3" between centers but I decided to let the casting be my guide and put things in the middle of each end.

Then I needed to solve the problem of holding this thing in the lathe so I decided as always to do it the most complicated way possible.
I made up some brass fixtures to clamp each end so that I could hold one end in the chuck and support the other side with the center. I made some pins to fit the holes each end and threaded the other end.
If you haven't tried a solid tungsten slitting saw I would highly recommend them!

I just used a screw on the small end. Once everything was aligned and tightened I squirted each end with super glue for good measure.

Final step was to use my taper turning attachment to machine a nice taper. The part was flipped to do the other side. I used a nice rounded form tool to give me some nice curved shoulders each end.

And there you have it. The plan called for a 1/16 relief on the side between the two ends. I did that on the back side but it didn't look as nice so I left the outer side unrelieved. When I cleaned up the sides of the big end I just supported it on pins through each end. This gave it a jaunty non parallel look. I'm not sure if I like that too much but I guess it will be ok.

Thanks for reading and for the great comments. More soon!

 

[delalio]

This is coming along beautifully! Well done!!

 

[Larry G.]

Next task was the con-rod. This started out as a little gunmetal casting which I cleaned up in the mill.

Then I needed to solve the problem of holding this thing in the lathe so I decided as always to do it the most complicated way possible.
I made up some brass fixtures to clamp each end so that I could hold one end in the chuck and support the other side with the center. I made some pins to fit the holes each end and threaded the other end.
If you haven't tried a solid tungsten slitting saw I would highly recommend them!
View attachment 112253

Thanks for reading and for the great comments. More soon!

Thank you for taking the time to post excellent photos and detailed explanations.
Where some model makers would have been satisfied to touch up the connecting rod with a bit of filing and belt sanding, your "most complicated way possible" approach produced a fine result.

Your toolmaker mindset is producing an excellent product.
I look forward to seeing more.

Larry

 

[LorenOtto]

Thank you for posting your build. You photos are very clear and the extra steps you take to turn a dreary set of castings into a thing of beauty and elegance are extraordinary. I am enjoying watching from afar.
Loren

 

[Emers]

Enjoying your build I am a new model builder myself ( 1 year) I like to watch every bodies builds keep up the great work.
Cheers
John

 

[jcreasey]

Apologies for the delay in installments. I got distracted by building this piece of nonsense. Normal service will resume shortly!

 

[jcreasey]

After much procrastination I finally got around to making the cross head. This shows the final reaming to size.

Next job was to tidy up the crank. Although the plans show it as a plain disk I couldn't resist the temptation to make it look a bit nicer. For this job I used my tiny 3" rotary table along with a little clamp I made for it. I made a couple of sacrificial pins that I could use to clamp it with.

 

[jcreasey]

Now to build the cam.
I really made a meal of this part but it got there in the end.

First I turned the outside diameter to rough size before reversing it to turn the other half so that I could hold it in a fixture.

I made this simple fixture to turn the eccentric sections and bore and ream the hole for the shaft.

I parted off too early having forgotten to machine the groove for the eccentric, but I recovered from this mistake using my collet chuck. I made this little parting tool to make the groove for the eccentric.

The plans call for 7ba here but I always use metric for grub screws. Mainly because I have never found anywhere that sells 7ba grub screws. It's easy to find 2.5m and the appropriate tiny sized allen keys to tighten them up with. Much nicer than a slot end.

 

[jcreasey]

Ok now to build the eccentric!
I cleaned it up a bit with the belt sander and drilled a couple of 1/8" holes in the two center points. This gave me a nice way to hold it horizontal so that I could clean up the side faces.

Once the sides were nice and parallel I cleaned up the other two sides.

A bit of stunt milling here using my little grinding vise to make clearance for the long tail of the eccentric by hanging it out over the main vise. I drilled the two bolt holes in the sides and then slitted the part along the center hole.

After bolting everything back together I could bore out the hole where the cam fits. I was going to solder the two halves together for this but the bolts seemed fine so I just used those. This caused no problems.

I used a nice sharp D-bit cutter to mill out the bore to fit my cam. It probably would have been much smarter to have made the the cam to fit the bore as I couldn't really do any test fits for this part. I did it by the numbers and everything worked out very well. It was a bit tense though!

To clean up the sides I bolted everything down to a nice piece of plate. I adjusted for the angle and cleaned up the top and bottom edges. I left the sides as cast. They are a bit thicker than plan but I think they look ok.

I spent a bit of time cleaning up the radiuses on the big end of the eccentric. This destroyed my bolts but I have plenty of spares. I used the allen key to provide friction while I rotated the part by hand against the cutter. Normally this kind of reckless behaviour sees me in tears with a destroyed part, but this time I got lucky.

And here it is all fitted together. The knurling wheel is just a temporary spacer!

 

[jcreasey]

One of the last remaining jobs is to build the slide valve. Not much going on here really, just some straight forward milling with tiny end mills.

 

[jcreasey]

Things are still progressing on my little mill engine build.
I decided I wanted some drain cocks for the cylinder but instead of doing the sensible thing and buying them I decided I would make my own.
Well one of the trickier parts to make is a little washer at the bottom which has a square hole in it. Of course to do that properly I needed a rotary broach. Of course instead of doing the sensible thing and buying a rotary broach I decided to make that too!
Don't you just love these rabbit holes that model engineering provides!

Here is my finished rotary broach. I used the Hemingway kit and it all worked out great.

That allowed me to make these tiny washers with square holes. Also one side was dished out with a ball nose end mill so that it would sit snugly against the base of the valve.

Once again I used my taper turning attachment to make the tapered section of the valve.
I also used it to make a little D-bit cutter which was used to make the tapered hole.

The bodies were shaped using a form tool. This photo shows things coming together.
I made the valves two at a time so I would have something to hang onto without wasting too much brass.
The tapered section has a square key milled in just above the thread which fits into the square hole. This prevents the little nut from unscrewing when the valve is opened and closed.

I made a super skinny little parting tool to separate the two valves.

Here are the completed valves mounted on the cylinder. There wasn't really a good spot to mount them on the casting so I used an 8mm end mill to make a nice flat bottomed hole. I then made some little round pieces of bronze which I brazed onto the side of the cylinder. These were tapped for the little valves and everything seems to come together nicely.

 

[bobden72]

Now that's what I call dedication and not taking the easy route. The end result looks great good job.

 

[Brian Hutchings]

Very nice build and thanks for the tip about making drain cocks.
Brian (almost at the centre of England).

 

[propclock]

Beautiful ! I just recently finished 4 very similar valves for a Tiny power
Twin. 4 required $35 each without shipping. Well that is motivation.
Yes it equated to about <5$ an hour for labor. I used steel for the
male portion. I didn't bother with the square portion, does it really matter. ? I feel your joy and appreciate your work. Thanks.