Tina :- Engine and Boiler Build

[klank]

Hi Strw

Yup - made from a kit of castings eventually furnished by a certain vendor (located up your way) after all kinds of trials and tribulation.

I just put the photos up to show a fish belly type of con. rod.
If you like draw - filing, its a good exercise - the trouble was getting two of them to look identical!
For Tina, one is no real problem.

Peter

[Rob.Wilson]

Hi Peter


Crank disc and other parts turned out spot on    ,,,,,,,,, 


Rob

[loco]

Now for the next exiting episode!!!

STAYS  These are only needed on FLAT sections of a boiler to prevent the sides bowing out under pressure. Consider a loco boiler. It basically comprises a cylinder fixed to a square or rectangular box. The  cylinder is self supporting whilst the box is not. At the front end of the boiler is a flat plate ( smokebox tube plate ) . This is stayed to the throatplate in the firebox by means of the tubes and is usually stayed to the backplate or backhead by means of longitudinal stays, 1 often being hollow and used for the blower. Remaining stays will be solid. They should be threaded, blind nutted and silversoldered. However, opinion varies as to the real use  of these longitudinal stays for after silver soldering such stays are observed to have sagged so much in the middle that their efficiency is doubtful.
The top or crown of the firebox is usually stayed to support itself the shape being round or rod stay, or of the girder type, these being usually riveted and silver soldered.
The firebox stays are the most important. There size and spacing should be chosen with care. They are there to support the unsupported sides which are not self supporting - got it??? The boiler designer will have done the calculations for the spacing.
This boiler is basically a self supporting structure. It needs no side stays and the tubes serve the purpose of longitudinal stays.
Fancy an experiment?? Find a square plastic bottle and a round one. Holding carefully half way up, blow into it and feel the sides expanding - or not. Notice how the manufacturer has added corrugations to make it more rigid. Think about the pressure inside - does it go fizz when opened?

Next time boiler regs and testing.
Pete

[loco]

Now for the next exiting episode!!!

This applies to the UK and those of you across the pond will have your own regs.
ALL new boilers need to be proved or tested. Would you buy a gun that had not had the barrel proof fired at twice the normal velocity? The initial hydraulic test is at 2X working pressure and such a test is valid for 4 years before the steam test. This allows s-l-o-w builders to complete. The holes are all plugged and NO boiler fitting should be on the boiler. Having passed, all the fittings are installed, piped up etc ready for a steam test at normal working pressure during which time the safety valve should be set and the pressure gauge red lined. A pass means the boiler is valid for 1 year. Subsequent hydraulic test shall be at 1.5 times working pressure annually followed by a steam test. This applies to all boilers over a capacity of 3bar/litres. The GLR boiler running at 80 psi just exceeds that level and requires CE marking if made commercially but is down rated to 40psi so it does not. If you are making it the 80psi is fine.
The kit of bits says 80 psi whilst a completed ready to run boiler is rated at 40 psi.
However every boiler I make is tested to 160psi hydraulically.

In a former life I was a teacher of engineering, metalwork and woodwork. About 20 plus years ago a lad built one of these boilers. After much soldering and resoldering and resoldering the boiler was finished and held 160psi.After he left and did not want the boiler my technician  decided a destructive test should be carried out. He made suitable plugs, secured with Boss white ( no PTFE in those days ), and after fixing it to a bench outside on the field and with the plugs facing the opposite way all was ready. Being the man he was,  readings were taken to see how much the barrel would bulge as the pressure increased. At 50 psi intervals we stopped and made measurements. The gauge only went up to 250 psi so we stopped. The increase was only  a few thou. No bangs, creaks or groans. DO NOT DO THIS TO YOURS. We cut the boiler in half to examine the inside and the tubes were perfect.

Pete

[loco]

help
I can build boilers but how do I put a photograph here???
Pete

[sbwhart]

help
I can build boilers but how do I put a photograph here???
Pete

This may help Pete

http://madmodder.net/index.php?topic=607.0

Stew

[klank]

Trying to get back to the engine build - the con. rod. next.

"Read the manual!"
In the build handbook, there is a chapter at the end - a sort of "addendum" - devoted to another more recent published article - appearing in MEW in 2009 - by Harold Hall.
He is dealing with basic work for a mill and rotary table, and uses some of Tina's castings to illustrate some techniques. Specifically, how to machine a round section/tapered con. rod and how to use a rotab. to finish the small end (rounding it off).
In this article, HH publishes a table of lathe dial movements (after some complex mathematics and other good stuff) for "saddle [X axis] and tool infeed [Y axis] so as to obtain the required tapered shape of the rod for Tina.
Unfortunately, for me, they are for an imperial dial measurement lathe (mine is metric), but it is quite simple to convert them. All of the X axis "slices" are the same, so all in all it is not a difficult job to follow.
HH's finished result looks a lot better than simply "taper turning" with the compound slide off-set - it's a bit fatter in the middle than Stan Bray's original, but still looks good.

This exercise looked far more interesting than a fish belly flat rod - so I discarded that idea.

I decided to set - to and see if I could turn up the same form, starting with a suitable length bar of BMS - 3/4" X 5/8" - which I had in stock. (Not supplied in the kit).
Following HH's notes, the bar is marked out to show where the big and little ends will be, the material in between to be turned away to a round section of the max. dia. of the con rod.

Bar marked out :-





The extra length will be turned down to a pair of spigots.
The bar was pop-marked for a centre at each end and put up in the 4 jaw with a tailstock centre and wobbler, to turn true. :-





A 1/2" spigot was then turned up to the end mark, and centre drilled. :-





The same procedure then carried out for the other end, and the meat in the middle turned away slowly, holding the bar in a collet and tailstock centre - as per HH's recipe. :-




Now came the interesting bit, following a table of 26 dual dimensions in X and Y axis to gradually turn away the material on one side of the centre so as to achieve the desired taper.
It wasn't as daunting as I first thought, and doing it slowly with care, the basic shape emerged, working from right to left from the mid point.

It was then necessary to do some filing/wet and dry of various grades to remove the machining marks whilst rotating at the same set up - here is the left hand side virtually done. :-





The same procedure was then followed working from left to right from the centre, without changing the set up (I don't know why a spigot at the other end is necessary, unless the set up is turned around end for end?) :-





The middle is now nicely tapered each way.
This leaves two oversized blocks at each end, plus the spigots.
The latter were sawn off, and a quiet hour spent on the mill to reduce the big/small end blocks to the required thickness and drill/ream the holes for the bronze bushes carrying the crank pin and gudgeon pin. :-





Now its a question of rounding off the perimeter of what will be the "small end" - HH recommending setting this up in the rotary table.
I have to confess to being a real novice at using a rotary table - so the possibility of making a bish of what I have got so far alarms me a little. I think I'll have to read up on Rotabs. for Dummys first!

More anon.

Peter

[klank]

I could not do a lot today, dentist appoitment interfered - such fun!

I decided to make use of a small home made receiver/adaptor with my rotary table.
This would allow the collet chuck to be fitted to it, thus holding the small end of the con rod on a mandrel, without going to all of the trouble in making "mounting fixtures" as shown HH's article.

After setting up everything to run true, I off-set the table by the appropriate amount and gently milled off the edges of the small end, taking light cuts around and increasing the down feed a bit at a time with an 8mm end mill. Here's the set up about half way through. :-




Two bronze bushes were turned up for the two reamed holes.
That bush in the "big end" is meant to be proud on both sides - according to the plan! :-





I will start on the main bearing castings tomorrow, toothache permitting!!

Peter

[Rob.Wilson]

  thats a mighty fine looking con rod  Peter 


Rob

[saw]

Nice work 

[klank]

Thanks Rob and Benni.

Workshop time was reduced today (had to go shopping with s.w.m.b.o. for her wedding outfit - number 1 son is getting married shortly - quite an experience, trying to be tactful, yet positive, whilst standing on razor blades).

Anyway - I started on the main bearing blocks.
The main bearings are solid gunmetal, split, but contain no separate bearing shells
These come as three castings - two separate "bases" and a pair of "tops", joined together. :-





The general quality of the castings was good, apart from the bottom of the bases being canted over somewhat, as can be seen above. Apart from that, they were all reasonably "square and true", although somewhat oversize compared to the plan dimensions.
Minimal dimensions are given - and not really needed - just the bolt hole spacings for both the bottom of the bases and the those holding the two bearing halves together, plus overall thickness and length of the base.
6 BA bolts are recommended to hold the two bearing halves together.

There are several ways to machine these - SB recommends doing them all in the 4 jaw (he did not use a mill at all in his notes), whereas HH recommends using the milling machine/toolmakers' vice.
I went the latter method - quicker set up time.
I have not bothered with mundane photos of doing the basic macining - points to note obviously are to get the centre heights exactly the same for each pair (using a height gauge on a flat plate or whatever), and the vertical faces at right angles to the base and parallel to each other.
Here's one lower bearing half part finished, compared to an untouched casting :-





I macined the top castings together, before separating them. :-





I temporarily joined the two halves together for each pair with cyano., not forgetting to mark each pair for re-assembly later.
Each pair was then marked out, drilled tapping size for 6BA (sufficiently deep to accommodate the supplied bolts - nice to have them as part of the kit), separated and the lower halves tapped, the upper halves opened out to 6 BA clearance, and the top faces where the bolt head will go, spot faced for the diameter of the bolt heads.
Each pair of bearings could then be assembled with the bolts..
I know that some may prefer to use soft solder thinly to join the halves together instead of cyano. - just my preference. It does hold quite well.

I chose to do the boring for the crankshaft pin in the 4 jaw, together with final facing and turning up the shoulder around the boss, which has been previously machined away when bringing the blocks to size.
The centre mark for the bore was measured, checked and centre popped.
I used a chuck back stop for this set up, which simplified matters considerably - you can just see it here behind the bearing casting :-




Slight digression here.
There have been many published plans/articles for making a chuck back stop, indeed Bogs has done a very good thread on this.
A friend put me in touch with a link (I cannot find it at present - if anyone else remembers where it is, please add it) for making a truly simple, effective yet elegant backstop requiring minimal components and machining - the picture here shows it far easier than words can explain - its "inventor" should be praised! :-





Each bearing block was set up as above, to turn true with a wiggler (wobbler?) and clock.
Centre drill, pilot drill, etc. and your choice to use a small boring bar (recommended) or reamer to finish. (Don't forget to withdraw the back stop a bit first!).
At the same time, the boss face can be skimmed and the shoulder turned back using a left hand tool.
The block was then reversed and put back in the same position in the 4 jaw/backstop, checked to run true and the other boss face/shoulder machining done.

The rest of the casting was then fettled and machined with a small end mill to remove the rest of the rough cast finish.
The tops of the bearing blocks were marked/popped for drilling/tapping the hole for the oil cup - but not finished at this stage.

Here is the result, temporarily placed on the base.  :-




The overall finish of the bearing blocks needs a bit of fine bench working and elbow grease.

Next up - the cylinder.

Thanks for the support

Best wishes to all

Peter
 

[saw]

You are doing very well, it's a plesure to folow your'e project. 

[NickG]

I think you've done a great job there because I don't know what anybody else thinks but those castings for the bearings look pretty awful to me. The fact that you've had to machine them all over makes it kind of pointless, it would have been easier from solid bar. They look great now by the way! 

Nick

[sbwhart]

Looks like you sorted them casting well Peter 

Stew

[klank]

Thanks again guys - you are very kind.

Nick, thanks. Given what you have said about these castings' "quality" and wih great respect and deference to your experience, I feel must have come across some truly shocking castings in the past and treated them as the "norm"!
O.k. my experience is quite limited - I have really only built two and a half engines from castings up to now and compared to what I have been presented with in those, I really thought these weren't that bad - being reasonably "true (ish)" and with no knobbly accretions.
Maybe I have made a mistake in machining all over, but once you start doing shoulders and such, bringing out the "shine" it made the rest of the surfaces look somewhat "rustic?"! So I gave it a shot.
I do appreciate all of your encouragement - compared to the other superb engines currently being built - this is playschool stuff.

Anyway - talking of castings - this is what is provided for the cyl. casting :-





To me it didn't look too bad, having checked its dimensions with those on the plan, and for "trueness" across the various faces. The only real problem side was the base, where it was partly canted from true to the valve port face - marked in felt tip.
Following SB's suggested method, I decided to start with the port face side of the casting as "datum" and set up for machining the base in my milling vice with the datum side against the fixed jaw, and "squeezy" packing against the cyl. body.
Once done, turned around to lightly machine the port face and check the results with a square.

The casting bore seemed reasonably "linear" throughout, and went ahead and plugged the hole at each end with some turned down wooden dowelling (a length sawn off the end of a garden hoe handle - I expect to get "sanctioned" in due course when my wife finds out!).
After a quick facing swipe across the disc sander, I could then mark out the bore faces for the true centre using a height gauge on my Tesco face plate and popped the centre mark.
I didn't bother with any photos of all of the above as its pretty mundane stuff, but here's the result :-





The casting was then set up in a Keats angle plate on the lathe faceplate, using the two finished faces to locate in the larger angle, and some scrap steel packing on the round cyl. body.
It was set to turn true with the usual wiggler from the tailstock and clock :-


 


Subsequent to this shot, I bolted a counterbalance weight to the face plate opposite the mass of the casting/Keats plate. The lathe would then turn reasonably steadily at about 750 rpm.

After skimming the first face it became apparent that there could be some small casting flaws hidden in the gun metal material. You can just see the "spots" dotted around the face here :-





They don't look to be too close to the bore itself and are very small - so I decided to press on.

The boring operation was quite straightforward and I didn't bother with photos of this.
Pilot drill through both bits of wood (there is quite a large central hole in my face plate), then drill out to 1/2" and start boring with a Glanze boring bar with the tip set on centre (it will quickly remove any residual wood from the plug). I used a bore gauge/micrometer to check the bore at various points down its length as it got close to size (1" bore required) and allowed for "spring" in the cuts.
Obviously, a better way of doing this would have been setting up the casting on the cross slide and boring between centres, but my Glanze bar is pretty rigid, and using very light cuts at the end, I am happy with the resut.
I left the bore a tiny fraction undersize, and finished it with some wet/dry paper and paraffin, wrapped around another length of Garden Hoe handle, turned slightly undersize and kept moving in and out as the casting rotated.

I faced the end (removing 1/2 of what I needed to overall to bring the cyl. to finished length) and cut the shoulder, reversed the casting in the Keats plate and did the other face/shoulder.

Following SB's advice, I checked the valve and base faces for squareness to each other and the end faces by bolting the cylinder to the cross slide, and interposing a 123 block between the valve face and the face plate (the latter having been ever so lightly skimmed) and checking for high spots/misalignement. (Sorry, the top slide toolpost spigot is in the way) :-





There was one slight high spot, and as recommended by SB, I fly cut the two faces ever so lightly from a cutter held in the face plate.

Here is the result :-





You can see the casting spots - enlearged here :-





There do not appear to be any imperfections running through into the bore, and I hope those around the rim side of the end faces will not be a problem, provided a good gasket is used between the end cover/cylinder at this point.

I shall start on the end covers tomorrow (provided I can hide the Garden Hoe again).

Best wishes


Peter

[saw]

I have to ask you Keats angle plate what is that???

[klank]

Benni
A Keats angle plate is a sort of cross between a V block and angle plate.
The "angle plate" part, can mount to the face plate through slots in its flange, but instead of a straight edge across the bottom, it has a deeply machined ninety degree V cut out at ninety degrees to the plane of the face plate.
Another ninety degree V machined plate bolts up to this leaving a sort of adjustable "square" shaped hole as a variable clamp - its pretty well shown in the third photo of this post. The flange and bolts holding the angle plate to the lathe face plate are hidden behind the bigger V and cylinder casting. The lower V plate and its securing bolts are quite clear.
I think Boggy did a write up of how to build one on MM a while ago?
I hope this explains.

Peter

[sbwhart]

Nice bit of maching their Peter. 

Those blow holes are nothing to worry about, they look to be well away from anything inportant.

Benni

This is Bogs write up on the Keats

http://madmodder.net/index.php?topic=1271.0

And this is how I made my own not the best looker in the tool box but it does the job.

http://madmodder.net/index.php?topic=3428.0

Cheers

Strew

[klank]

Thats some nice tooling Stew,

Thanks for showing how it should be done!

Peter

[NickG]

Peter, I was maybe a bit hasty in my judgement sorry if I came across in a bad way and I don't have much experience working with castings, you probably have more. I was just the close up pics of the bearings that got me, I just thought what use is that shape ... then I scrolled down and saw you had machined it all over, which I think looks great but possibly defeats the point of having a casting slightly? I know what you mean by the temptation to make it all shiny though! As you say though, as long as you can get the required dimensions out of them and they are reasonably true / free from blow holes then maybe that's a more important measure of the quality. I see you've found a few on the cylinder but as Stew says, at least those ones won't be affecting anything.

Great work.

Nick

[klank]

Hi Nick,

No, not at all did you come across in a "bad" way, nor was it a hasty judgment - I appreciate your views.
The trouble with machining all over is you can never get rid of machining marks in those "hard to reach" areas.

Here's a thought - if the unmachined surface is pretty flat and linear - leave it alone - maybe a lick of paint would serve? (Paint would "take" a lot easier on a "rough" surface than a shiny one).

Thanks for the kind thoughts Nick - a pleasure to read your post

Peter

[saw]

Thanks for explaining, there is a lot of diffrent tools and I have just a few 
I think I have to spend some time to make me some..

[Bogstandard]

I would just like to add, the Keats angle plates seem to have become unobtainable from our normal suppliers, but if anyone would like to try making one, the castings can be obtained from here


http://www.collegeengineering.co.uk/Castings/558.htm


Bogs

[saw]

Thanks for the links Bogs.

[loco]

Hi

Keats type angle plates are available from Warco.
Pete