CHUK2 - Alyn Foundry Flame Gulper

[Twizseven]

Finally bit the bullet and decided I'd better try and do something with one of my casting sets.

I recently visited Graham Corry and had a set of the CHUK Flame Licker/Gulper castings off him.  Several members of this forum have built this engine over the last couple of years, including very recently Jo and also Graham himself.

I'm sure my build will be a demonstration of how not to do it.  I decided to start with this engine as the castings are of a reasonable size unlike some of the other sets I have squirrelled away.

This will not be a quick build and I'm sure there will be the odd swearword as I progress, or don't. as the case maybe.

I started with the base casting and due to its relative size decided to use the Colchester Student and its large 4 Jaw chuck.

This is quite an awkward casting to hold and i eventually managed to get it centred and held against the chuck jaws by means of large revolving centre in the tailstock pushed hard up against it.

I wear glasses but decided to play ultra safe and wore a full face visor whilst cleaning of the diameter and base and the inside bore.  The thought of it flying out of the chuck did not appeal.  Used tipped tool and ran at a nice slow 54rpm.

The centre of the underside will have to be cleaned up at a later point in time as I had nothing I could use to get between the revolving centre and the casing.

Please feel free to point out any stupid practices or to provide helpful suggestions.

First photo shows the set of castings.  In Picture 3 you can see part of the casting where the mould had a little issue.  I had to be very careful when cleaning this area up.

Colin

[Jo]

  Nice to see some progress on your Chuk Colin.

I don't think I bothered with turning the outside/bottom of my base as it decided it was flat enough and it was supposed to be a casting 

Jo

[Alyn Foundry]

Happy New year Colin.

Mirroring Jo's comment, likewise.   

I've mentioned many times that I spent hours at the premises of AWR engineering, learning or trying to learn the " craft " of  machining. Many of Alex's jobs were small batch repetition. His philosophy was that you only changed lathe chucks when " absolutely " necessary. It's not only time consuming but heavy work if you're running a large lathe.

I designed the pad for the cylinder mount to be compatible with my 8" monoblock 3 jaw chuck, the square bit would " just " fit between two jaws. Once running fairly true you can centre spot and bring in the tailsock rotating centre for added security.

The use of the four jaw chuck obviously improves the grip immensly and in the Model engineering workshop time is spent pleasurably, I hope? 

I'm very pleased to see that you didn't encounter the same problem as I did with my base.

Please don't hesitate to ask questions Colin, and don't forget to post with the FB group.   

Cheers Graham.

[Twizseven]

Hi Graham, Happy New Year to you.

When I came to look at the base in daylight to mark the center for the exhaust port I realised that although the casting was centred nicely in the chuck when I machined it when looking at the top face the the boss was around 5mm off centre.   This would have irritated me for ever.

I lightly cleaned up the face of the boss on the linisher and then put a coat of marking out blue on it.  As the main diameter of the boss appeared to be 60mm I cut a paper circle out to this size and placed it over the marking out blue.  Then able to put a nice centre pop in the middle.

I used this centre pop to centralise the base in the 4 jaw chuck, the faced it off, drilled and bored the 20.5mm hole for the exhaust  exhaust port and recessed the face for the exhaust valve and very slightly for the base of the cylinder.

Then turned a 20.5mm mandrel clamped the base to it and refaced the outer and inner faces of the base.  Much happier with the result now.

Then decided to have a go at the flywheel.  Mounted in in the 3 jaw chuck with the jaws opening outwards to hold the flywheel to the chuck.  I had to pack one jaw with a double thickness of cardboard to get it to run true but I only had a 5mm register to grip the flywheel.  I centred the boss and used the revolving centre for additional support.  I was able to face the periphery of the flywheel and the front face but due to jaw location could not do rear face.  I wanted to clean up the centre boss whilst it was supported by the centre.  I needed a long narrow right hand tool which unfortunately I do not have.  Tried many options and suddenly had a light bulb moment.  I could turn my left hand tool upside down and run the lathe in reverse.  Amazingly it worked,  The finish was not prefect but at least I had removed the outer hard skin of the casting.

I removed the revolving centre, drilled 6mm, 8mm, 9.8mm through the boss and then machine reamed it to 10mm.  This all went ok so turned flywheel around and cleaned up remaining faces and the other boss.

Will attack the cylinder next.

Seems to have taken me a long time today.

Colin

[Twizseven]

Current state as end of day

[Twizseven]

Decided to start with the piston and get it down to largest size possible.  It cleaned up at 40.34mm diameter.  This gave me something to aim for whilst boring the cylinder.

The piston has quite a casting draft and it needed a good push with the tailstock onto the chuck.  Was not happy holding it on external surface but held it internally on the small 3 jaw chuck on the Myford 7.  I also cleaned up the inside.  Started with boring tool then cleared the bottom of the casting with a 10mm carbide slot mill held in the drill chuck in the tailstock.  This was an interesting exercise, the drill chuck in the MT2 tailstock kept kicking up.  This finally stopped once the bore had started and it could guide the cutter.  I finished with a 5.5mm piston crown and wall thickness around 3.5mm.  These will both be thinned down once piston sized to bore.

Then moved onto cylinder. Unfortunately the jaws on my 3 jaw chuck were not deep enough to hold onto more than one cylinder fin.  I had in all centered and started to  gently machine the end face.  This finished with a very slowly occurring disaster.  The cylinder decided to remove itself from the chuck.   Luckily no damage was done. I found some of the brown stuff I had just removed from my fathers workshop which was almost the right size for the bore.  Quickly turned it down and made a short plug to put in the end of cylinder.  Now able to hold the cylinder on the first section of the cylinder before the start of the fins.  This worked great and soon had the face nice and flat.

Fitted the big 4 jaw chuck to the lathe and put the newly faced side against the chuck, bit of cardboard between the casting and the chuck jaws and centered it all up.  I just used a rough block of wood between the casting and the tailstock centre to hold the casting flat against the chuck.  Centered the casting using a combination of the fins, bore and outer end of the cylinder.  I left the block in place whilst turning down the end of the cylinder to provide a suitable surface for the fixed steady.  I have never used the steady before.

Fitted the biggest/longest boring tool I have got, 7/8" square Sandvik Coromat.  The first few passes i did by hand but then used power feed to take out 1mm at a time. I had decided I could go as close to 40mm bore diameter as possible.  At 39.970mm I then ran the tool back and forwards under power for three full passes.  This took around 1hr.  Final dimension would appear to be 40.15mm.  I have measured this using spring calipers telescopic gauges and then reading them with micrometer.  They both concur and not only that the bore appears to be parallel.

Tomorrows task is to find a honing tool.  I used to have one of the spring cylinder hones but last used it 30 odd years ago.  It appears to have vanished.  Once I have honed the bore I will get the piston down to final size.

Colin

.

[Jo]

Doing well Colin 

Those brake honing tools are very cheap on Flea bay. For the outside of the piston: you don't have much to come off I find holding a stone against the outside is a good way of honing it to take off that last fraction for the fit.

Jo

[Twizseven]

Jo,
I’m please with how it’s going so far.  Should have a brake cylinder hone by 5 this afternoon.  Planning on leaving cylinder in chuck and putting hone in tailstock.  Run at slowest 54rpm with some paraffin and see what transpires.
I think The piston will need a quick skim first before stoning.  I was thinking of using 1200 grade wet and dry again with paraffin or possible oil.

I am hoping to leave the cylinder in the Colchester and machine the bearing standard on the Myford.  I am hoping to be able to make the stand an interference fit (or loctite if I get dimensions wrong).  The plan is to bore out the outer portion of the stand whilst it is held on long mandrel ( simlilar to the way you held yours).  I can then machine appropriate dimensions on the cylinder on the Colchester.

Colin

[Jasonb]

Looking good

You may want to up the speed with the hone to avoid stalling your so far rapid progress, I then to run then 500-740rpm. I tend to use the drill press as you can work the hone in and out faster with the quill to get a cross hatch or better still a sit's not that big a bore just hold in your hand and work up and down. Doing it with the tailstoke will give more of a circular hone, also run the stones just beyond the end of the bore, hopefully you have a big enough hole in the chuck to do that if sticking with the lathe.

Back any abrasive sheet with a bit of flat bar, MDF or steel rule.

[Twizseven]

Jason,
Thanks for that tip.  Many years ago I had to hone the bores on a 803cc Standard  8 engine.  I used one of the larger 3 stone spring loaded hones and my fathers antique Wolf Power drill.  This was a big drill with IIRC a 300rpm top speed  I used this and kept raising and lowering it in the bore till I was happy with the result.  Knees and back were b......d by the time I had finished.

Will back the 1200 wet and dry with  piece of steel rule.

Colin

[Alyn Foundry]

Your progress is rapid Colin, well done.

Ah, Wolf power tools, well built and unstoppable!!

Whilst still an apprentice at the Water company I remember two of the garage staff drilling a large hole with a two man Wolf drill.  Next thing, it bit in hard and the two guys ended up running around the work until the power cable pulled out of the socket. 'Twas scary at the time but everyone laughed about it later.

I too have one of those drills you used Colin, with the older, better drill bits of the past they could easily become a wrist breaker, you had to be on your toes!

Cheers Graham.

[Twizseven]

Graham,

I still have the drill.  It has a lot of torque.  As well as handle with trigger it has a chest brace and a 1" dia steel tube on opposite side to handle.  It has swung me round many years ago in the dim and distant past.

Just picked up brake cylinder hone.  So tonights job is...............................boring.....sorree honing

Colin

[Twizseven]

As I said in last post, a boring evening.  I started of leaving the cylinder in the lathe chuck and used electric drill with the cylinder hone attached.  This was not very comfortable so put cylinder in vice and found this a lot easier. Once I was in position that the head of the piston would enter the cylinder about 5mm I reversed it and tried the open end, If did not fit then polished the piston up concentrating on end that did not fit.  Kept alternanting between running the hone down the bore and polishing piston as required.  Was 90% of way there when wife who had gone to bed rang me to say I was making too much noise (tapping piston out of bore with broom handle) as it was 11:30pm. Oh Dear  What a shame. Gave up for the night.

Next morning carried on for around 1hr till piston slid nicely from one end to the other.  Just had to part it off from the fixing stub.  Before removing this stub I drilled 4mm for a 2BA tap for fixing gudgeon pin fork.  I put it in 3 jaw chuck on Myford  with cardboard round to prevent damage but did not want to tighten it too much as piston walls are just under 1.5mm.  As soon as parting tool touched it started to move, stopped quickly and decided that careful use of hacksaw was required.  Once sawn off I was able to reduce top of piston  by 1.5 mm to 3.5mm.

In order to finish machining the cylinder I needed a solid mandrel on which to mount it.  Found a suitable length of (dubious) steel and turned it down from 25.6mm o just over 22 mm for most of its length.  This left a shoulderat the end nearest the chuck.  Turned the other end down ready to run a M16x2 die over it for a fixing nut.  Could not work out whether it was the steel or the die that was absolute rubbish.  In the end I had to turn the end down well below 16mm dia and was left with threads minus their crown.  The nut still holds.   Next need a pair of washers with 22mm bore and spigot 40.3mm for a good fit in piston bore.  Found big chuck of steel, Chucked it up and put centre in end then turned it down to 46mm.  Removed centre and fitted fixed steady then drilled out at 3/4" and started to bore for 22mm.  By now it was 21:30p.pm and time to go to pub for a pint.

Colin

[Alyn Foundry]

Hi Colin.

I've just noticed that you haven't got the " lip " at the top of the cylinder  for the exhaust disc, is this the next operation ?

Cheers Graham.

[Twizseven]

Graham,

Yes that is next operation once I have made the sized washers to hold the cylinder central on the mandrel.  At moment staring at a piece of 1/2" brass deciding whether to machine it down ti make the gudgeon pin boss.

Also just ordered some 1000 grit silicon carbide for giving the piston/cylinder a quick lap.

Colin