Double Tangye Steam Engine

[smfr]

This build is definitely relevant to my interests! Will be interesting to see how you do the various bits of remediation, Jo 

Simon

[Jo]

For a quick win I decided to give the cylinder heads a clean up and ignoring the odd hole in the underside of the gasket face they don’t seem too bad. Except that they both only fit on one cylinder in one location: This is normal for a model of this age when people often marked out by hand and seven is not an easy number to mark out.



Thankfully the heads were only drilled with the tapping size and could be quickly taken out for the studs .

On a first look at the drawings you will notice that a great many dimensions are missing. This is because the engine needs to be built to the dimensions of the castings. What the drawings does provide is a guide to where the centre line of the cylinder should be and you drill the mounts accordingly. So having cleaned up/derusted the base and given the underside a coat of anitrust primer the top, it was time to start thinking about marking the base for the stands. That meant looking at the stands themselves and to make the most of the mill and square up a few bits and pieces. First both stands had a nasty lump at the end of the crosshead that was milled off:



Then it was time to clean up the crosshead cutaway:



Time to remove the standard governor mounting lugs. The one on the left has had them removed the one on the right is just about to be treated to a bit of loving fettling  :



The two stand were filled where necessary using JB weld and left to cure… So time to look again at the base. I wandered over to the surface table put it on and it rocked. The top rocked and the bottom face rocked: In different directions! So time to mill the bottom flat. The rock was taken out using two feeler gauges on the two opposite sides:



But the base is wider than my milling machine so it was necessary to turn the work around and have another go to get at the other side:



I don’t trust the accuracy of this set up so I decided to test it on the surface plate. Yes  there was a high point in the centre. So a bit of engineers blue on the plate rub the casting over it:



And there is our offending high point. Off with a file!

Now that she will sit flat it is back to the mill. You can see how bad the two corners were by the initial cut on this corner:



It actually worked out that I had to take off 0.7mm! to get it flat. So a little surfacing tool I happen to have did one side, then the other:



It is not a bad finish. Now I have a surface on which I can mark out the centre lines of the cylinders and stands.



I have also been painting, rubbing down, painting.. I do however have a need for a few studs Did I ever mention the pleasure I get out of my studs?

Jo

[Dave Otto]

Hi Jo

It's great to see another new project to follow along with; and it appears that you are wasting no time diving right in.

The top side of the base would have been a nice job for a shaper.

Dave

[steamer]

Messin with Blue!.....I'll get you scraping something yet!

Looks great Jo!

Dave

[Jo]

I have done my morning’s exercise of rubbing and painting and am waiting for it to dry to be able to continue so time to continue with the Double Tangye. I note that the JB Weld has matched the cast iron very nicely.

The engine stand have had both their base and the backs made square, these are now our references for the remainder of the work. We now need to find the centre line of the cylinders. The cylinder mounting flange is slightly proud of the rear face so it was necessary to put a parallel under it:



We now measure the top of the flange from the surface plate and take from it half the  diameter of the flange:



This now allows us to mark the cylinder centre line for reference and the bolt down holes that can then be centre punched, using an optical centre punch:



The Casting levelled up in the a machine vice under the drill:



Supporting the overhanging end to make sure it stays level, it can then be drilled for the three mounting studs.



Looking at the base there is a taper from front to rear so it was necessary to mark the centre line by measuring rather than with the height gauge. Laying the stands on the base you can see, from the crank laying at the rear, that the theoretical distance apart is too wide:



 So to find the correct distance we are going to have to wait until the crank is complete  .

Jo

[Stuart]

Jo looking good its got to be a case of better to start with new castings than ones that have been played with.

but is this a case of
1 they are not available
2 they came so much cheaper this way


good work with the demos in setting up and with a coherent commentary ( mine would be un followable ) will help the tyros that come by this site , as well as the seasoned members

we are never to old to learn something however small a new way of looking at a problem  often comes up


Stuart

[Jo]

Stuart: I paid £100 for this set of castings They are still available from rip off Reeves if you want them new and will cost a  sum of money. 

The next casting I need to tackle had already been bored: the wrong diameter

Jo

[Dave Otto]

Seems like it would be better to have the stands centered on the base and adjust the length of the crankshaft to suit? I'm sure that there is more invloved and you already have a plan moving forward.

Dave

[Jo]

The distances given are from the centre line of the casting, which is not symmetrical 

I'm sure that there is more involved and you already have a plan moving forward.

  My plan is to do what I always do.. make it up as I go along. 

And I have a much more interesting problem in that the two stands have been machined different lengths, the right hand one is 0.6mm longer than the one on the left.



Now I could just ignore it and take it up in the piston rod  But I also need to look at possible ways to machine the back face of the cylinder mounting flange. In the meantime I am back making the next bit for the S&P 

Jo

[NickG]

Nice start Jo, I'll be watching.

[Jo]

So more casting challenges  . The big end caps have had their tops filed to a rough round shape. However they are supposed to end with oil pot at 45 degrees:



I also did not get any ideas for machining the back of the cylinder mounting flange. So another view of the problem, my red paint stick is pointing at the flange that needs the back edge machining. :



As you can see the base flange is in the way to stop it being mounted on a lathe face plate. So guys I am open to suggestions  .

Now that I have made today’s progress on the S&P it is time to make some swarf on this  .

Jo

[steamer]

Upside down boring bar....and run the lathe in reverse with the part mounted to a knee and a face plate

Dave

[Jo]

If the boring bar goes in at 90 degrees the base will hit it 

Jo

[Captain Jerry]

Jo

I'm sure that you have a better view than I, but from here, it looks like the material needs to come off of the face of the flange.  I am basing that on your photo of the pair viewed from the top.  It looks like if you were set the two parts with the flange faces even then part on the right is too long and neither the lugs nor the shoulder of the bearing bracket will line up.  If I am seeing this all wrong, I'm not surprised.

Jerry

[steamer]

If the boring bar goes in at 90 degrees the base will hit it 

Jo

Hook type boring bar....looks like a  bar with a parting tool set perpendicular at the end.

Dave