Bolton 12 Beam engine from scratch

Peter, I am loving your work especially your inventiveness and work arounds. It is providing me with some great ideas! Thanks for sharing. DW

Thanks Cymro, more hit and miss than inventiveness, Regards, Peter

Some days, time spent in my shed is just the best, everything runs smoothly and nothing could be more enjoyable. Yesterday was not one of those days, in fact it was the absolute opposite. First I broke an end mill, a 12mm one at that, by doing something stupid, then the Z axis of my mill jammed in the up position. After looking at the drawings in the manual, I decided that it must be something to do with the nut that engages the vertical leadscrew. Two hours of messing about, pulling the head off the machine, no mean feat when it is jammed in the uppermost position, I discover the culprit is a grubscrew that has wormed its way out of the driver pulley at the top and snagged the rim of the mounting plate. Ten seconds to put it back in with locktite, fixed.The head didn't need to come off at all. I almost wept with frustration. Another couple of hours putting it all back together, tramming the head, gnashing my teeth and cursing my stupidity. I watched my dear wife tending the geraniums in her garden and I started to wonder if it was time to look for a more gentle hobby.
Well, tomorrow is another day, thank God.
Regards, Peter

I have far too many of those days myself. Yesterday I studied the electric fan in my shed to get the correct pitch on a cooling fan I'm building (cos I couldn't find one the correct pitch) and failed to take into account my electric fan spins in the opposite direction to the one I'm building. So yes, my shiny new brass fan has the wrong pitch... To add insult to injury I picked up a piece of brass that was so hot it made my fingers smoke. I called it a day at that point.

Back in the shack. I really need to push on with the outer bearing mount because I need to get the flywheel and shaft mounted. This will determine location and alignment of the various linkages. The drawings offer little so I decided to fabricate a mount and attach it to the bottom plate of the engine. I decided to use substantial sections of aluminium as this whole arrangement is cantilevered off the side. The spacing has to be sufficient to allow for an additional transmisson pulley to be located on the shaft. This will be connected to a small DC generator located on the bottom platform, giving a load to the engine when it is working. In actual fact, most of the time the DC generator will act as a motor. This will allow the engine to be displayed in "dynamic mode". (Love all this modern jargon, once we would have just said "working"). As always, the pictures tell the story much better than I. I made a holder for the rounding bits as 20mm is the largest ER32 collet I have and that worked OK. The results put me in a lot better mood then the previous day, this is turning out to be one giant engine.
Cheers, Peter

Not a lot of activity to report. Decided to make the main crankshaft bearings ant then use those to decide on the shaft design. Still battling with the drawings but at the end of the day I would not have been able to get this far without them. I will make the shaft from some 22mm silver steel I have but step down to 15mm or so for the bearing journals. I can see that some of the previous work will have to be re-done, the outer bearing support now looks to be too far over. Once the shaft and bearings are all located I will be able to take some measurements for the connecting rods. A few pics of today's work. Regards, Peter

After I finished the bearings for the crankshaft I realised that the engine had a tendency to heel over due to the weight of the flywheel and support cantilevered off the side. Time for a change. I did not like the top of the outer bearing support, so I decided to make a whole new support and have it as a foot for the machine as well. I milled the outer bearing down to 16mm so it now sat flush on the support and looked much better. I turned the shaft from a piece of 22mm bright and reduced the journals to 14mm. The two shoulders of the shaft fit snugly between the bearings so no end float. I milled a 6mm x 3mm keyway in the shaft, then set up the flywheel in the mill for the keyway. I milled down with a 6mm endmill set so that it only chewed a 3mm groove down the FW bore, then finished it with a file. I don't have any broaches. I made the key from brass. To keep the FW in place on the shaft I made a collar with a 5mm grubscrew and bolted this collar to the hub of the FW. A quick dimple in the shaft and smiles all round, I was having a good day. Everything bolted together OK, the FW spins nicely in the bearings. Domestic duties for the next few days unfortunately, but I think I've reached about the half-way point. Cheers, Peter

Very quiet all week painting bathrooms. That's enough on that subject. The only thing that has happened on the project front is the arrival of the bevel gears I ordered from Hong Kong, these are needed to drive the governor. I think these are from a Bosch angle grinder, A$9.50 freight paid. I ordered them on the 21 Feb and they arrived 9th March which is pretty good service. For lots of reasons I don't think this hobby would be possible without the internet, not for me anyway. I will attempt to machine them when I get back from Canberra, which is where I will be for a week. Any advice on working with hardened parts would be welcome. Until next week, Regards, Peter

Peter,
They look like compressed powered metal gears, if they are they will be hard and there is very little that can be done with them as they will break. They are a very long lasting and wearing gear if they have enough lube.

Cheers
Andrew

Hi Peter, I used angle grinder gears for the governor of my Bolton 12. I heated them red hot and slowly cooled them several times, and was then able to machine them with carbide insert tools. John johnsmachines.com

Hi Peter,
love your work, I built a #12 a couple of years ago, see attached video
[ame]https://www.youtube.com/watch?v=fB8IPPFz8nU[/ame] I have a spare cast iron
beam unmachined that you may have for free, I live on mount tamborine
not far from you,as for the bevel gears I made my own from brass,an involute
cutter is only about $15 and you have all the tools needed, something to think about,

Thanks John, your kind offer is appreciated and I would like to contact you. We are only 30 min from Mt Tamborine. Until next Tuesday I am in Canberra looking at, amongst other fascinating things, Cockington Green miniature village and the flowers in the company of my darling wife. (Sigh!). But I will be back in the shack by the middle of next week, hoping to get started on the project. As for the gears, I would love to attempt to make them, possibly I could pick your brains. To anyone else reading this, Canberra is the capital of Australia and the home of the Federal Government. I personally feel it is the perfect place to keep all our politicians, however, the War Memorial is a must see, and I don't say that lightly. Some pics of the village,
Cheers, Peter

Hi Nhoj,

The cutters I've been finding are more like $45 USD. I'd like to order a pair of 32 DP #3 and #6 cutters to make gears for an Eagle I.C. engine.

I've only built steam engines up to now, I have a little beam engine I designed and build about 10 years ago on by Sherline lathe and mill, similar to the Bolton an the Stewart Major Beam (much smaller!). I'm interested in your boiler. Can you give me a link to info on it?

Thanks,

Alan

nhoj said:

Hi Peter,
love your work, I built a #12 a couple of years ago, see attached video
https://www.youtube.com/watch?v=fB8IPPFz8nU I have a spare cast iron
beam unmachined that you may have for free, I live on mount tamborine
not far from you,as for the bevel gears I made my own from brass,an involute
cutter is only about $15 and you have all the tools needed, something to think about,View attachment 87839

Click to expand...

Hi Alan,
all of my cutters have come from CTC in America and are listed as $16.20 each
unfortunately they don't seem to carry 32dp cutters, a quick search brought up RDG in England have 32dp cutters for $28.16 each,the boiler was purchased
from Maccsteam LTD. located in England in 2014 for 1064 pounds delivered,
a bit pricey but extremely well made, it has twin burners, runs on lpg and had no trouble getting an inspection certificate in australia,
cheers John.

Thanks John,

Seems like CTCtools sells the modulo cutters. I do see some on Victornet that could work.

http://www.victornet.com/subdepartments/14-1/2-Degree-Gear-Cutters/1660.html

Nice boiler, a little bit much for me. I'd like to build one.

Alan
Central Coast, CA, USA

nhoj said:

Hi Alan,
all of my cutters have come from CTC in America and are listed as $16.20 each
unfortunately they don't seem to carry 32dp cutters, a quick search brought up RDG in England have 32dp cutters for $28.16 each,the boiler was purchased
from Maccsteam LTD. located in England in 2014 for 1064 pounds delivered,
a bit pricey but extremely well made, it has twin burners, runs on lpg and had no trouble getting an inspection certificate in australia,
cheers John.

Click to expand...

Back to the real world. The gears I brought from HK, (see earlier post) were just as hard as everyone predicted. I tried to bore out the crown gear but it soon became apparent that this was a waste of time. A tip from OLIOMIO (John Viggers) on this forum suggested heating the gear and then allowing to cool slowly might help. I wasn't convinced but decided to try anyway. Total success! The gear was still hard, much like 316 SS, but quite easy to bore out to size as well as drilling and tapping for a grub screw. Thanks John and all the others who have offered their insights and advice, this forum has many benefits, not the least the enjoyment I get from writing about this project. The gear is now snug on the shaft and I can take some measurements. The eccentric will be fitted between the gear and the bearing pillow block and the space between the gear and flywheel is for a double groove rope pulley to drive a load located below on the second "floor" of the model. I have been researching rope transmission belting but haven't discovered much. If anyone has any advice it would be appreciated, particularly on how to join the rope. Further progress might be a little curtailed over the next few weeks as the bathroom painting has shown how shabby the rest of the house is. Bugger, I hate painting. Cheers, Peter

Thanks for the mention Peter! I have posted a video and other pics of my Bolton 12 running on steam and construction at johnsmachines.com. John

A bit of a break in the project due to a nasty weather event on the east coast of Australia, we missed most of the winds but made up for it in the rain, I need a new rain gauge calibrated in feet instead of inches. All this water showed up a few deficiencies in my shed that needed to be addressed before moving ahead with the project but I am happy to say that I'm back in the shack and the sun is shining once again. If I needed any incentive to finish this engine it received a boost when I met NHOJ, a member of this forum who contacted me, and as he lives close I visited. John has completed this steam engine from a casting kit and if I can do half as good a job as his finished masterpiece then I will be satisfied. John had two main castings left over from the kit and was kind enough to offer them to me, the entablature and the beam, these had been duplicated in the castings he obtained. I accepted these with deep gratitude and would like to once again say "thank you" to John.
Back to my effort and the rapidly drying shed, I decided to make the rope pulley that is located next to the flywheel. I cut the 100mm blank and bored the centre to the shaft size. I don't own any broaches so I cut the keyway with a file, then drilled and tapped the rim for a 5mm grubscrew. The pulley does not have a hub so I thought that this would be the easiest way. The blank was now mounted on the shaft in the lathe to complete the turning. I wanted to do it this way as I have a bad habit of turning up pulleys that have a wobble when mounted to a shaft. I made a small form tool for the grooves, this worked OK I suppose but the chatter was dreadful. When they looked about right I cleaned them up with a round file and then paper, added a bit of a profile to the cheeks of the pulley for appearance and called the job done. I thought it looked fair enough at the finish, time will tell. Next, on to the beam. Cheers, Peter.

On to the beam that was given to me by NHOJ. I must confess that I have never had anything to do with castings as supplied in kits, so I was looking forward to the exercise. Should be fairly easy, cheating a bit compared to scratch, or so I thought. The quality seemed pretty good to me, the only problem that I could detect was that it has a definite bend along its length but as I can see no way of correcting that I decided to just leave it. The first step was to machine the axle bosses down to flatness and size, this was easy enough and things were going swimmingly. I blued the bosses after the machining, established the centre of the middle boss and used this point to reference the centre points of the other hubs. Except that the centres were off by quite a bit when compared to the actual centre, so here was a problem. If I centred each hole in the centre of each hub, the result would be pleasing to the eye but the relative distances between the axles would be wrong, If I made the distances correct, two of the bosses would look as if they had been drilled off centre. I decided to fudge it and go for what looked OK without being too far wrong. I drilled the centre boss dead centre and worked outward and the result looked pretty good, that is until I turned the beam over. To my horror, the hole drilled through the centre was way off and the result looked bloody awful. The other bosses didn't look quite as bad but were still pretty grim. I cursed my lack of experience with castings and now realise that I should have taken a decent set of measurements before starting, then at least I would have known just what I had to work with. It was now obvious that the bosses were not perfectly aligned with each side. I'm not sure what I could have done but I'm pretty sure I wouldn't have done what I did. Bugger! In the end I milled the centre hubs off entirely, this corrected the visual abomination. I machined two brass spacers that fitted snug between the bearing blocks and the beam and the result is passable. The other hubs I decided to live with. The underside of the beam was drilled and tapped for grub screws to locate the axles and the beam was finished. As always, this hobby has a habit of showing you how little you know, not how much and I was a much chastened and more humble person than when I started the beam. I now think that doing a model from castings would be MUCH more difficult that I had previously thought. I think I need a good scotch to revive my ego. Cheers, Peter.

"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