Author Topic: Stuart “Minor” Beam Engine Build, 12 years and counting  (Read 3774 times)

Offline Djangodog

  • Full Member
  • ****
  • Posts: 68
Stuart “Minor” Beam Engine Build, 12 years and counting
« on: March 08, 2023, 07:13:34 PM »
I am posting this thread to document the build and to point out any issues with the castings or drawings or machining operations.  I understand that the Stuart Beam build has been done in the past.  I hope that my build log won’t be completely redundent. 

I think that I bought this casting set in 2010 or 2011.  A previous owner had begun to machine the cylinder and flywheel.  Fortunately, they had some material left on most dimensions, and I will adjust the mating parts to correspond with the surfaces that had to be taken down below the dimensions on the drawing.

A word of caution regarding old castings and new drawings.  Stuart made some changes over the years and if you are working to the newer drawings and have old castings you will find out that the castings for the crankshaft bearing, (old), are not wide enough to work with the tapped holes in the base, (the old bearings are 1 3/8” and the new base drawing has them at 1 1/2”.  I will make the bearings from solid stock to match the holes that I put into the base.

I am glad that I still had my surface grinder when I began this build.  As I generally do, (I have only built a few engines, so generally is a stretch), I began with the base, (skimmed the top and bottom flat and parallel and then surface ground the surfaces, centered up the casting and put the holes in, (straight forward except for the bearing spacing issue).

I am also glad that I still had my south Bend Heavy 10 back when I did the flywheel.  The back gear was needed to avoid chatter.  I don’t remember exactly how I went about machining the flywheel.  My best guess is that I roughed it out using a four jaw chuck and finished it on a mandrel.  There are still some casting defects, but I can live with that.  It runs true and looks decent, so all is good.

Because of the previous work, I had to take some parts of the cylinder undersize.  The overall length and bore are to print, but I will have to reduce the outside dimensions and hole patterns of the steam chest and cover to compensate.  I do have a spare cylinder, but it’s not a great casting.  I have not decided yet if I want to use it.

That was where I left the engine twelve or so years ago.

Today’s job was to machine the column.  The casting was a bit rough and being that the column is a central part of the engine, I decided to machine everything.  As typical, I centered the two ends and mounted the part between centers.  I cleaned up the back face of the top portion and them faced the end to the .500” dimension.  I turned the columns around and repeated the operation and brought the overall length to 6”.

The center portion did not run very close to the outside surfaces of the flanges, so I held the top of the column in a four jaw chuck, squared the face and got the column running as true as a casting can and using a small boring bar, I carefully bored the center on the other end so that it ran reasonably true to the cast column.  Supported by the tailstock center, I was able to clean the column, (I had to remove approximately 1/16” for it to clean.

The mill work was fairly straight forward and there were no surprises.  I may leave the column bare.  I have plenty of time to make decisions regarding finish.

That’s all for today.  All comments and advice, good bad or indifferent are welcome.

Thanks
« Last Edit: March 12, 2023, 04:53:01 PM by Djangodog »

Online Kim

  • Global Moderator
  • Full Member
  • *****
  • Posts: 7082
  • Portland, Oregon, USA
Re: Stuart Beam Engine Build, 12 years and counting
« Reply #1 on: March 09, 2023, 05:19:36 AM »
I'll look forward to following along with your build!  :popcorn:
Kim

Online Jo

  • Administrator
  • Full Member
  • *****
  • Posts: 15099
  • Hampshire, england.
Re: Stuart Beam Engine Build, 12 years and counting
« Reply #2 on: March 09, 2023, 07:37:38 AM »
The standard sized Stuart Beam engine is a very forgiving casting set/model and for that reason ideal for a beginner so you will be amazed what you can get away with and yet it still runs well.

Jo
Enjoyment is more important than achievement.

Offline Jasonb

  • Full Member
  • *****
  • Posts: 9009
  • Surrey, UK
Re: Stuart Beam Engine Build, 12 years and counting
« Reply #3 on: March 09, 2023, 07:59:41 AM »
Long time since I made mine

Regarding the bearing pedestals what heights are shown on the new drawings? They only seem to list one casting now and if that is the 1.5" spacing one it is 7/8" tall at the split rather than 5/8" so may also affect con rod length. I've seen people having the tall casting for the Victoria and you end up with the crankshaft ctr line above that of the cylinder.

Offline wagnmkr

  • Full Member
  • ****
  • Posts: 807
  • Lindsay, Ontario, Canada
Re: Stuart Beam Engine Build, 12 years and counting
« Reply #4 on: March 09, 2023, 10:59:46 AM »
One of my favorite engines. I will be watching this one.
I was cut out to be rich ... but ... I was sewn up all wrong!

Offline vtsteam

  • Full Member
  • ****
  • Posts: 733
Re: Stuart Beam Engine Build, 12 years and counting
« Reply #5 on: March 09, 2023, 03:21:05 PM »
 Watching along. :popcorn: :popcorn: :cheers:
Steve

Offline Michael S.

  • Full Member
  • ****
  • Posts: 810
  • Germany, Saxony-Anhalt, Magdeburg
Re: Stuart Beam Engine Build, 12 years and counting
« Reply #6 on: March 09, 2023, 06:05:38 PM »
I built my Beam machine in 2005. The blueprint and the castings matched.
What I can still remember were the glass-hard spots on the underside of the machine base.

Michael

Offline Djangodog

  • Full Member
  • ****
  • Posts: 68
Re: Stuart Beam Engine Build, 12 years and counting
« Reply #7 on: March 09, 2023, 07:50:51 PM »
I built my Beam machine in 2005. The blueprint and the castings matched.
What I can still remember were the glass-hard spots on the underside of the machine base.

Michael

My castings are fairly old and they came with a drawing that I assume was original.  I wrongly assumed that the latest drawing would simply be more accurate and because of its size and the separation of parts, be easier to use.  The attachment shows where I went wrong regarding the base and the bearing castings.  I know better than to not compare the two drawings.  I also see another discrepancy regarding the distance from the  base of the cylinder and the location of the bearings for the valve actuation mechanism. 

I got lucky today.  I found that I had a piece of C544 Bearing Bronze that I can make the lower half of the bearings from.  I am now going to review the entire drawing more carefully and convert all sizes to decimal inches.  I will also notate any changes required to account for the slightly altered cylinder.

 

Offline Jasonb

  • Full Member
  • *****
  • Posts: 9009
  • Surrey, UK
Re: Stuart Beam Engine Build, 12 years and counting
« Reply #8 on: March 09, 2023, 08:27:44 PM »
It is possible to make the pedestals and caps from something like steel or aluminium and just fit separate bronze bearings, have a look at my post just over half way down this page which will save expensive bronze. Bit late now but the 2BA or 10-32 which you may be using is also a bit on the large side.

https://www.model-engineer.co.uk/forums/postings.asp?th=168849&p=32

Offline Djangodog

  • Full Member
  • ****
  • Posts: 68
Re: Stuart Beam Engine Build, 12 years and counting
« Reply #9 on: March 10, 2023, 12:25:52 AM »
It is possible to make the pedestals and caps from something like steel or aluminium and just fit separate bronze bearings, have a look at my post just over half way down this page which will save expensive bronze. Bit late now but the 2BA or 10-32 which you may be using is also a bit on the large side.

https://www.model-engineer.co.uk/forums/postings.asp?th=168849&p=32

Thanks.  I had considered making the base of the bearing from steel.  I also considered plugging the holes and relocating them to the 1 3/8” spacing.  I already have the Bronze and it will match the rest of the engine, so I will probably go that way.

I agree that the 2BA holes look a bit large, but that was the specified thread.

Offline ettingtonliam

  • Full Member
  • ****
  • Posts: 119
Re: Stuart Beam Engine Build, 12 years and counting
« Reply #10 on: March 11, 2023, 02:43:58 PM »
I notice that you said that you surface ground the base casting. Back in the day, up to 1974, anyway, Stuarts stated in their catalogue, that they surface ground the base casting, because it only took them about 70 seconds on their surface grinder, so it seemed a reasonable thing to do. By 1995, there was no mention of this anymore, so presumably they'd stopped doing it.

Offline Djangodog

  • Full Member
  • ****
  • Posts: 68
Re: Stuart Beam Engine Build, 12 years and counting
« Reply #11 on: March 12, 2023, 04:20:17 PM »
I notice that you said that you surface ground the base casting. Back in the day, up to 1974, anyway, Stuarts stated in their catalogue, that they surface ground the base casting, because it only took them about 70 seconds on their surface grinder, so it seemed a reasonable thing to do. By 1995, there was no mention of this anymore, so presumably they'd stopped doing it.

The cast base that came with the casting set was ground, but the casting was so poor that I sent to Stuart for a new one.  The replacement was not ground.

I have only built a 10H and D10 with reversing, so I don’t have much experience with model castings.  The 10H and D10 castings were quite good, but these castings have been disappointing.  The 5A that I finished for my father only had a few Stuart castings and since my father had already machined them, I can’t say anything about the quality.  I do know that they were not machined below the nominal dimensions and had no imperfections remaining. 

The beam was extremely rough and the 3/8” width was already .360” in some areas.  It mostly cleaned up at .352 and I can alter the other parts to compensate.  The distance from the center boss to the next was off, so I milled around the smaller boss with a ball end mill.  The worst of it was a blow hole in the casting where the crank pin passes through.  I was leaving a little stock to bore, but the drill walked far enough off that it left me with an elongated hole.  I bored the hole to .219”, (7/32”), and will adjust the crank pin to compensate.  There is still a void in the hole, but it should be fine, (most of the hole is full and the larger pin should more than make up for the void).     

I kept one of the Moore boring head sets and my R8 adaptor.  I miss that jig bore, but the Bridgeport bores quite well, especially when using a good quality boring head.

The first image shows the blow hole before I bored it oversized. 

The other engines are shown for comparison of casting quality.  No filler was needed.
« Last Edit: March 12, 2023, 04:31:17 PM by Djangodog »

Offline vtsteam

  • Full Member
  • ****
  • Posts: 733
Re: Stuart Beam Engine Build, 12 years and counting
« Reply #12 on: March 12, 2023, 04:52:34 PM »
Djangodog, sorry to hear about the poor quality castings. As a person who casts iron for my own projects, that's very disappointing to hear. Seems like the beam had three strikes against it. The blowhole is unacceptable, as is the undersize casting thickness. The latter is a fault of the pattern itself, and the boss distance problem might be also, unless it was caused by the pattern shifting.

At any rate, the molder is not doing even rudimentary checking of the finished casting, if it's under-thickness. While people expect castings to need machining for precision, there must be enough material to do that, and a check of overall dimensions for something this size is easily done. Castings are expensive these days, and basic QC ought to be applied. If a pattern is undersized, every casting will be, so it's in a foundry's own interest to check at least the first casting.

An internal blowhole is the only problem that would have been missed if there had been any QC, the main cause is too much moisture or poor permeability of the sand. That's an actual molder's problem, rather than a pattern maker's.

At any rate, good of you to save the part, and lucky you could work around the problems. Sorry you had to.  :cheers:
« Last Edit: March 12, 2023, 04:58:05 PM by vtsteam »
Steve

Offline Djangodog

  • Full Member
  • ****
  • Posts: 68
Re: Stuart “Minor” Beam Engine Build, 12 years and counting
« Reply #13 on: March 12, 2023, 11:49:46 PM »
It’s beginning to resemble a beam engine.  I machined the entire cylinder cover so that I can leave it natural.  I still have some hand work to do on the beam.

The cylinder will get made over tomorrow and I hope to machine the steam chest as well.  After that it will be onto the glands, bearings and crank shaft. 

 

Offline Djangodog

  • Full Member
  • ****
  • Posts: 68
Re: Stuart “Minor” Beam Engine Build, 12 years and counting
« Reply #14 on: March 13, 2023, 10:54:56 PM »
I decided to go with a new cylinder so that the steam chest and cover will be close to the dimensions on the drawing, (.025” under in width and height and not quite clean).  All holes are in, including the four 8BA for the straps over the lagging. 

The blemish near the exhaust port is a casting defect. 

The steam chest, cover and glands are next.




 

SimplePortal 2.3.5 © 2008-2012, SimplePortal