Bolton 12 Beam engine from scratch

[KM6VV]

Even machining an intricate beam out of bar stock (brass) can have it's problems. I was just finishing up the outside contour for a 9" beam on my Sherline mill, and the part nearly jumped off the bed when fully cut out! Stress had apparently built up in the part due to a considerable amount of pocketing (CNC).

I don't remember if I had to do anything to it (about 10 years ago), but the engine turned out OK. (Sherline-sized copy of a large beam engine).

Previous to that I had started a Stuart 10V, but I apparently set it aside, and opted to design and build a similar engine out of bar stock to gain some experience. And then a few other engines...

Now I'm trying to find the drawings for the 10V, and Andrew's book: "Building a Vertical Steam Engine". (Semi-retired now). And finish it up.

Alan

"I now think that doing a model from castings would be MUCH more difficult that I had previously thought."

You are quite correct in that assumption Peter.

Beginners are the usual people to fall into that trap, they assume it would be easier to make from castings rather than bar stock, but because you are at the mercy of the casting suppliers getting things spot on, and most times they are not, many sets of castings end up under the bench because the parts required couldn't easily be got out of the casting supplied.

I spent many hours putting right the mistakes other people had made on their castings, just so they could carry on to finish their project.

John

 

[deeferdog]

After all the problems with the beam, I was starting to suspect that I was entering one of the hardest parts of the build. Although I had maintained accuracy with most of the dimensions of the plans, my approach was different enough to cause headaches and the connecting rod to the crank was looking difficult. The connecting rod in the kit, I assumed, is one casting. I decided that it would probably be easier to fabricate this as an assembly rather than cut it out of one piece of stock. The connection to the beam could be achieved by making two cheek bearings and then joining them to the connecting rod so I decided to give this a shot. The pictures tell the story and I was reasonably happy with the results. The other end of the assembly, the crank, gave me much more of a problem. It took a long time to set up, I used the rotary table, and the cutting out was tedious. I set the angle with my trusty little electronic protractor, what a gift from the Gods these things are, and machined either side. I turned the crank pin to a nice tight fit, Lotited and pinned it in place, cut the keyway with a file and I was finished. Not bad, but the bit in the middle is going to give me sleepless nights. Whatever project I attempt after this is going to have a proper set of drawings, or I'm going to have to learn to use Autocad properly. I really can see the benefit of drawing something before attempting the build, and by drawing, I mean an accurate, fully dimensioned one, not the miserable sketches I limp along with. Enough whinging. Cheers, Peter.

 

[kvom]

"I now think that doing a model from castings would be MUCH more difficult that I had previously thought."

I'll echo my agreement with this sentiment. Even with good castings the problems start with holding the raw parts to make the first couple of cuts to get datum surfaces. And the smaller the part the harder the job.

An extreme case, for me at least, is the Stuart 3 cylinder compound kit I purchased recently. Several dozen castings, and other than 3 of them I'd likely make these parts from bar stock.

I did build one engine from a casting kit (Joy valve engine), but the parts were quite large with lots of excess material. It was enjoyable to make but I'm not looking to do another anytime soon.

My current project is Anthony Mount's Benson engine, available as a kit from a UK supplier. I'm attempting it from barstock rather than the casting kit, so there are some challenges on duplicating some of the castings. Nothing insurmountable so far.

 

[deeferdog]

When I started the connecting rod I have to admit that I didn't really have a clear idea as to how the completed article would finish up. I took a piece of 30 mm aluminium round and machined two flats at the end to match the width of the beam and fitted the two cheek bearings I had made previously. This worked out OK and now I at least had a connection to one end. After a lot of fiddling around and one failed attempt I decided to make the crank end connection and then join the two parts into one connecting rod. This sort of muddle engineering occurs when you don't have a drawing of what you are trying to make. I'm used to it but it can be frustrating, I really envy others who make a three D drawing first and can see just what will fit where. I bored out the top part of the rod to accept the crank connection which had a shoulder machined such that when inserted to this would result in the whole being the correct length. I Loctited this into place and secured it with two 3 mm roll pins. When I assembled this arrangement to the engine it worked quite well. I put it back in the mill and machined some flutes into the body and rounded off some bits to improve the appearance, in the end I was reasonably happy with the results but if anyone is reading this and thinking "what a complicated way to end up with a simple thing" then I can only agree. This project is no longer a case of light at the end of the tunnel, more like first finding the bloody tunnel. Tomorrow will be better. Cheers, Peter

 

[deeferdog]

I suppose one of the advantages in scratch building is that you can change your mind more often and change the project as well. I decided that the rope drive pulley just didn't quite have the look and as I had two gears from the post drill that I had purchased in an attempt to have a cast iron flywheel, well, now looked to be a good time to use them. The large gear was bored out and I press fitted a piece of aluminium round stock, this gave me a shaft to hold the gear in the lathe. I faced off the casting to remove an eccentric lobe and form a true hub, then parted off the roundstock and bored out the hub to the crankshaft size on the engine. I had to angle drill the hub and tap a 6 mm thread for a retaining cap screw. Everything went well and the gear sat nicely on the crankshaft and the model now had the look I was looking for. The smaller gear was machined and bored for a small layshaft which I decided to mount under the main platform of the model. I made two pillow block bearings for this and eventually got them located in the correct position. (I made a complete pig's ear of the first attempt, four more holes to plug and file back.) The main platform had to have an indent machined to allow the layshaft to finish inside the overall width dimension of the model. Eventually, this shaft will have a pulley made for it and this will be driven by a small sewing machine motor, this will enable me to satisfy the curious who would like to see the machine in action without having to connect to air or steam. I want to try and disguise the motor so that it looks more like a generator but that's for a later time. Once again, the pictures tell the story. Regards to all, Peter

 

[deeferdog]

Now seemed a good time to do the eccentric. I could see that it was going to get tight in this area as after the eccentric I would have to make the mount for the governor, time will tell if it is all going to fit. The eccentric was relatively easy, I made the bearing lobe from a piece of hex brass stock then parted it allowing extra thickness for the hub. the shaft centre was marked, bored and the keyway filed out. I mounted this on the crankshaft and turned down the hub in the lathe afterwards drilling and tapping for a 3 mm grubscrew. The outer part of the eccentric, I have no idea what it is called, I made from aluminium bar bored out and split as per the pictures. The end result looked OK, I decided to mill off the corners for a bit of eye appeal. The next bit will be harder, I have to work out just how to connect this to the valve train, still, things are humming along so sod's law says that a gutzer is just around the corner. I wish I had been born an optimist! Cheers, Peter.

 

[deeferdog]

Connecting the eccentric to the crankshaft, as per the drawing, was by keyway with the maximum height of the eccentric sheave at 90 degrees to the crank web. I hope they are right as timing a steam engine is not my long suite. The connecting rod from the eccentric strap, (I've being doing a little homework on the naming of the parts of an eccentric) to the valve shaft would be 6 mm aluminium, this would be threaded into the strap and the other end threaded into a brass axle. The axle would be free to rotate between two jaws of the valve shaft crank. The work went OK and assembly and dis-assembly of the whole arrangement is reasonably easy. The pictures should explain and I made a quick video of the project so far, the model is still a bit rough in parts but then so is my ability. The bottom photo is sideways, sigh. I look at some of the other offerings in this forum and realise that I am on the bottom rung of an extremely tall ladder. However, I get a lot of pleasure out of this challenge, I hope that it brings a small measure of enjoyment to those of you who have been following this. Comments are invited and appreciated. Cheers, Peter.
PS The video will be on the next post. Hopefully.

 

[deeferdog]

Third attempt at this video! What is a security token?

 

[Cymro77]

Sorry old chap but I have not a clue, perhaps the administrator can help!

 

[deeferdog]

Sorry about the video, I have notified the Administrator of my problems and will wait a reply. In the meantime, stills will have to do. Cheers, Peter

 

[Cogsy]

deefer - you just need to upload your video to youtube and post the link in a post for it to show the video in the thread. Just make sure the link is along the lines of htt p//youtube.com/watch=654sdfh5465s and you'll be fine.

 

[deeferdog]

Thanks Cogsy, I'll give it a shot later today. Cheers.

 

[deeferdog]

Here is the link to the video. This shows the progress on the project so far.
https://youtu.be/ZWobjwB71ks I estimate that I am over half way but not by much. The video is pretty basic and I don't expect any messages from the Academy. Experience will make them better. Thanks again to Cogsy.
Regards, Peter

 

[Cogsy]

Looking really nice so far. Did you use youtube's "let us fix the shaky video" feature? In a couple of shots I see some wonky looking parts that then straighten out on their own! Your youtube link is almost right, but you need the one where it's not split like youtu.be. Post the one that you get from clicking on the link above and it'll work like this : [ame]https://www.youtube.com/watch?v=ZWobjwB71ks&feature=youtu.be[/ame]

 

[deeferdog]

I removed the shakey fix feature. I've got a bit learn. Thanks for your help.

 

[deeferdog]

Back in the shed after a week away at Woolgoolga, a sleepy little township just north of Coffs Harbour, very relaxing. On to more serious stuff. The drive shaft for the governor runs through an arched shaped casting, which of course I didn't have. It was fairly easy to work out a design as the bevel gear on the crankshaft dictated where the drive pinion would have to be. I mounted a chunk of 16 mm thick aluminium on the rotary table and milled out the shape. After some initial hand finishing, two brass bearings were fitted to support the shaft. I'm not too sure if these are really necessary as the shaft runs in the vertical but they are not too much trouble to fit. For the shaft I used a piece of 6 mm aluminium round, the hard part was fitting the pinion gear, and when I mean hard I'm referring to the hardness of the gear. I heated it to cherry red and allowed to cool slowly as I had done with the bevel gear but drilling through it with a 3 mm drill for a roll pin took some time. The drill bits are good quality Suttons used with Rocol cutting oil but they didn't last long. I'm a pretty average drill sharpener at the best of times and with my eyesight a 3 mm drill bit is a challenge to say the least, but I eventually ground my way through and fitted the roll pin. I have to admit that I broke two of the bits, sigh!
Well, that's where I'm up to at the moment, next will be to finish the brass shaft carrier and fabricate the governor linkage. I will be posting a little infrequently for a short period as the house painting has been brought to my attention again, bugger.
Cheers for now, Peter.

 

[deeferdog]

Well, a respite from the painting. Decided to go ahead with the governor shaft carrier in brass to add a touch of jewellery to the finished model. I think that this will be one of those things that prove to be much harder than it looks as the linkage for the centrifugal weights has to be attached as well. I machined the basic shape from a piece of hex brass bar, putting a slight taper for effect. I had an old brass lamp I had picked up at a car boot sale for a dollar and I cut the end off this and fitted it to the base to improve the appearance. The smaller movable top part was a bit fiddly, like making a chess piece but I was happy with the result. If all this sounds like a bit of wood turning rather than precise engineering it's because that's pretty much the way I approached it. There are few critical measurements, the most important thing is that it works, I hope that it does! At the moment I still haven't worked out how to attach the linkage, or even how to fabricate them, perhaps after a good inhalation of paint fumes it will come to me. Watch this space. Cheers, Peter

 

[deeferdog]

The ongoing saga of the steam governor, I spent most of today filing and fiddling with bits of brass and aluminium and at the end I think that I'm getting somewhere. I estimate that I've got around the same amount of time still to spend before it's finished. A lot of this sort of work is not my long suit by any means and it tries my patience but it sure beats painting. The pictures tell the tale far better than I. The next step is the two brass balls. That should prove interesting and the pressure on. Until then, Regards, Peter.

 

[deeferdog]

Sorry for the lack of posts, other projects, including the painting have interfered. Two more weeks and I should be back. Regards, Peter

 

[deeferdog]

Looking at my last post I realise that the break has been a bit longer than I intended, however the time has not been wasted. My shed is very small, 3 metres by 3 metres and as the steam engine has started to come together it has taken up so much space that it really has become a bit of a nuisance. I haven't weighed it but I guess it must be around 10 - 12 kgs and my back is not getting any younger. So I bit the bullet and decided on some extensions and these have been occupying me time up until now. I managed to add an additional 4 square metres and even though the shed is now an odd shape I don't mind. To me it is heaven. Of course I filled it all straight away but at least I no longer have to constantly move things around to find a bit of bench space. I also finally managed to quieten down the air compressor (See my post in Machinery mods if interested), it's not brilliant but I can think when it cuts in. So, that's it for now. Hope this is not off topic. I will be back on the real job tomorrow. Regards, Peter.