Hunslet 5 inch gauge build.

[Roger]

A cracking job Malcolm, and a great result. I'm curious to know why you drilled all the intermediate holes for the ports instead of just milling them? I can see why you would want to do the end holes, plunging vertically into the work is a bad idea.

[rrmrd66]

Hi Roger and thanks for the compliments.

To answer your question. Don Young states that a 3/16" slot drill/end mill always cuts over size. So use a size smaller. This I did, indexing +/- either side of the nominal center line.

Therefor the initial task was to rough out the slot. In my simple mind a drill is quicker (and cheaper if disaster occurs) than a milling cutter. That's it.

Cheap Chinese metric drills for "hogging out" metal and expensive carbide slot drill for a delicate finish.

regards

Malcolm

[Roger]

Fair enough, there's no right way to do it. There's a risk of going too deep with the holes and you have to work out where they go, those are the only down sides, but it's no big deal.

You're absolutely right about roughing it out first, whatever the method. I've experimented with various strategies using CNC and even on the simplest of jobs, you get better control of the final size and finish if you rough it out first.

[rrmrd66]

Good Evening all.

A few weeks have gone by since my last update. Lots to show, so lets get on.

CYLINDERS PART 2

I finished my last posting with the promise that I would show how, following in between centres boring of the cylinders, I attempted to face the cylinder end faces square with the bores.

Here is the tool I turned up from 1.75" Al. bar to 1.625" dia. This was clocked in the milling vice in all directions and clamped up. The cap, secured by a socket head cap screw, compresses the O ring sufficiently to expand radially and clamp the cylinder casting to the aluminum shaft (or so I hoped).

P1010285 by Malcolm HARWOOD, on Flickr

The finished height of the cap was below the end of the casting so that I could run the end mill across the face.

P1010284 by Malcolm HARWOOD, on Flickr

Pride cometh before a fall, as they say and the milling forces were sufficient to overcome the O ring clamp and spin the casting on the shaft ( or at least try to)!

I thus resorted to a more positive clamping arrangement.

P1010286 by Malcolm HARWOOD, on Flickr

Following establishing one face normal to the axis of the bore I was able to flip the casting over and mill square and to length.

( Oh no! It's those pesky apprentice made parallels again )

P1010287 by Malcolm HARWOOD, on Flickr

At some point, if you are following this thread and making your own Hunslet remember that the cylinder drain cock threaded holes have to put in and that when you come to drill the cylinder end faces there is a potential problem about to occur.

Note the white plastic spacer, much beloved by window and kitchen fitters. They come in varying thicknesses and colours and are a real time saver, even if not quite ME standard!

fullsizeoutput_6e5 by Malcolm HARWOOD, on Flickr

Don Young's words and music covers construction of both 5" and 7.25" gauge loco's.

The 7.25", called John Hunslet (the 5" is named Don Hunslet ) has a 7/32"ME thread in its outer end cap and he advises doing so for the 5" version. Although it means that you have to make a couple of 7/32"ME threaded plugs it does allow you to use the riser on the casting as a chucking spigot.

A dummy mandrel, with the 7/32"ME thread can then be used to turn the inside face with mounting spigot as well as the OD.

fullsizeoutput_6e3 by Malcolm HARWOOD, on Flickr

This chucking  spigot can be used in the three jaw chuck on the rotary table to drill the 11 mounting hokes in the cylinder end cap prior to removal.

I subsequently made two 7/32"ME plugs from hex brass bar incorporating space for a fibre washer.

At this point you will note that there are 11 holes, not equipspaced due to offsets to enable the steam passages from the ends of the cylinders into the steam chest.

DY suggested that one of the holes were to be at 6 o'clock but this coincides with the previously mentioned drain cock tappings.

Solution is to move this hole slightly to the left, about 7°. Look I have even got the Tan tables and the old Zeus chart out to confirm.

P1010295 by Malcolm HARWOOD, on Flickr

Next, it was meant to be all down hill from there on.

Oh no it wasn't.

Question. If a man drills and taps 11 6BA tapped holes which number hole does he break the tip of the tap in?

Answer: No.11, of course.

What to do next ,is then the question.

P1010299 by Malcolm HARWOOD, on Flickr

After failing to mechanically extract the tip of the tap I resorted to a bit of electro-chemical trickery.

I have often read about dissolving ferrous metals in non ferrous castings with an Alum solution

The internet suggested that this was not always successful although one guy in New York knew how to do it correctly.

First you should use Alum (Aluminum Potassium Sulphate) from a chemist and not the domestic dye fixer type.

Make a saturated solution. (The point at which the crystals will dissolve no further) in very hot water. Just simmering.

You will need at least 250grammes to 250ml of water. Possibly more.

Immerse the casting in the solution and keep the temperature just below boiling. You should see, almost immediately. a stream of bubbles emanating from the broken tap.

Leave cooking, 5 hours in my case,until the bubbles stop and the tap will have disappeared. Magic.

Here is my Master Chef set up.

P1010302 by Malcolm HARWOOD, on Flickr

After that little episode it was back to turning the cylinder gland end cover.

Don Young obviously had a sense of humour because it takes about a day looking for a detail drawing of the gland follower to find only a small note to say that they are the same as the gland follower in the eccentric driven boiler water feed pump.

So where are the castings in the expensive Reeves "package deal complete casting set"? Nowhere! Shall I make them from solid bar with most of the bar being swarf of buy two more castings from Reeves, pointing out that they could, to their benefit, include them in the set and charge accordingly? This suggestion was received with what I would politely call '"indifference". Always a pleasure to spend money with enthusiastic suppliers.

Yes, sharped eyed readers will notice a spacer disc at the back of the flange. This was to throw the surface about to be machined clear of the chuck jaws.

P1010296 by Malcolm HARWOOD, on Flickr

There was recently a discussion about the use of the compound slide on the lathe. I started boring the gland on the with a  very thin and ancient HSS tool that would allow me to turn the bore and also internally face it of square by judicious use of the compound slide, forgetting that I had not clocked it to the lathe axis and ended up with a tapered bore. Very naughty.

I discovered my mistake when about 10 thou over and managed to rectify it with a proper boring bar on the next gland. Result is to have two dissimilar gland followers that are not interchangeable. Not the end of the world, but annoying.

P1010297 by Malcolm HARWOOD, on Flickr

Next up was drilling/milling the steam passages from the ends of the cylinders to break into the slots in the back of the steam chest.

This is not easy and after a fruitless attempt to determine the angle in CAD  (Oh! The shame) I did a full size drawing and reckoned it was a tad over 40° to the horizontal so set up my trusty tilting table and plunged in.

The problem here is the steam passage is about 1.25"-1.5"long x 3/16" dia and long slot mills are not readily available.

Many thanks to the 4 fellow members of the forum who made various helpful suggestions ( You know who you are!).

In the end a combination of needle files and rotary burrs on the Dremel with a flexible shaft won the day.

This shot shows the vertical set up of the casting at 40° with a set square lined up with the centre of the steam a passageway in the back of the steam chest.

P1010303 by Malcolm HARWOOD, on Flickr

So that is about it for today. I am now on with the piston heads and rings upon which I will report back shortly.

Thanks for staying with me this long I hope you have found it interesting and maybe even a little educational?

Cheers

Malcolm.

[simplyloco]

An excellent post: a cut above?
John

[rrmrd66]

Thanks John

Someone, who shall remain nameless but is in a position of seniority, remarked when informed I was building a 5"gauge Quarry Hunslet "why didn't I build a proper engine"?

Good motivation for a newcomer to the hobby, don't you think?

Malcolm

[Roger]

Hi Malcolm,
Excellent setups and a great result. Just one thing I would have done would be to put a generous flat on either side of the round mandrel where it was being held in the vice to make it more rigid. Round things held vertically can also be held more securely by the use of a Vee block between one side and the vice jaw.

I'm paranoid about breaking small taps, so I have a couple of things I always do. Firstly, I never use the tommy bar to turn the tap, it's far too easy to get too much force. I use just fingers and thumb on the body of the wrench.
Secondly, if it's taking more force than I'm happy with, and that's most of the time, I keep switching between say first and second, or second and bottom taps, sometimes barely making any progress on each fraction of a turn. Any progress is a victory on full threads in difficult materials. Obviously some materials are easier than others, but this also holds good for when the tap is past its best and takes more force to take a cut. Everyone breaks a tap from time to time, I just try to make that a very rare occurrence!
Another thing I sometimes do if it's a blind thread is to work out how many turns it is before hitting bottom. That lets you know if you've got it deep enough and also acts as a warning when you're likely to hit the bottom and potentially break the tap.

[rrmrd66]

Hi Roger

Glad you spotted that one.

In fact, although the photo doesn't show it at all clearly (and I forgot to mention) there are two flats milled into the Al. bar. But thanks for pointing it out for the benefit of all.

Re. Tommy bars I was using the smallest Eclipse tap holder and just caught my finger on the side with a momentary wobble! Result=snap.

The plug tap was still 90% complete and with a bit of hand grinding I made a "new" plug tap with almost no lead on the tip. The depth of thread was only 0.180' (DY suggested 0.140") so I was pushing it a bit.

I was trying my best not to break through the casting whilst obtaining max thread length. I will use stainless studs as opposed to hex headed screws then I will not have problems with the screw "bottoming out" in

the threaded hole.

Good tip about counting the number of turns.

regards

Malcolm

[johnthepump]

Jun 29, 2018 20:52:06 GMT rrmrd66 said:

Thanks John

Someone, who shall remain nameless but is in a position of seniority, remarked when informed I was building a 5"gauge Quarry Hunslet "why didn't I build a proper engine"?

Good motivation for a newcomer to the hobby, don't you think?

Malcolm

Hi Malcom,

I have only just found your thread, very interesting keep up the good work I shall now follow it. As to proper engines its a matter of personal choice, for me narrow gauge every time. My interest is not of express locos hauling carriages full of people, but the little quarry engine moving the hard won slate in and from the Quarries of North Wales.


Regards John.


P.S. It was Don Young that Mentioned me as John the Pump in Locos Large and Small.

[rrmrd66]

Good Evening to you all.

Those of you who have been following my long term build thread ( intended for rank beginners, like me) were possibly expecting Cylinders Part 3!

This is not the case, this time, and I will revert to finishing them shortly.

As you will know the cylinders are integral with the valves/valve chest assembly and it is this that I have been diverted to.

So. Here goes.

The valve chest body is a lump of gunmetal and needs machining all over. First operation is to mount it in the four jaw chick and face it up.

P1010305 by Malcolm HARWOOD, on Flickr

Because of subsequent operations I faced the opposite face in the mill and used my fly cutter.

If the tool is allowed to pass over the face completely, it cuts on the "back swing" and leaves a very fine finish.

fullsizeoutput_6ef by Malcolm HARWOOD, on Flickr

It is worth pointing out that if the casting riser/spigot(s) are to be used later on make sure that you don't remove too much of any one face and move the centers to far to one side making the spigot of no use.

(Ignore the Sharpy mark "felt tip" centre above. It is not of use. The scribed center and the distance mark on the face being machined, below, are accurate and of use)

fullsizeoutput_6f1 by Malcolm HARWOOD, on Flickr

I now have two faces and two sides faced up and square and I have mounted the valve chest back in the four jaw, with packing pieces to protect the faced surfaces, in order to turn the spigot into a chucking diameter that is  true  and a face that is square to it and the other faces.  ( Hope that's clear?).

This spigot will eventually be removed.

fullsizeoutput_6f3 by Malcolm HARWOOD, on Flickr

I am then able to turn the valve chest around in the chuck and true up and face the other end and drill, tap and counter bore as it is to be the gland for the valve rod. 3/8" x 32tpi ME thread.

fullsizeoutput_6f7 by Malcolm HARWOOD, on Flickr

The opposite face of the valve chest has now been drilled, reamed and tapped for the valve spindle support piece.

Once again the valve chest has been marked up on the surface plate with a vernier height gauge with lines " over which I must not stray" if I want to arrive at drawing dimensions.

Depending on how small you think the corner radii should be will determine the diameter of your cutter. I have use a long reach 4mm cutter here.

It is that this point that my mind turns to Roger and his love for CNC. I have two valve bodies to machine internally and even with DRO assistance I have to remember (write down) 4 pairs of X and Y coordinates to make sure I arrive at what I want by hand feeding from one XY to the next XY. Be careful it is easy to go wrong! Maybe CNC could be the way to go??

fullsizeoutput_6f9 by Malcolm HARWOOD, on Flickr

Chucking spigot now removed and valve chest internals to drawing I am now boring the steam exit passage union thread.

Incidentally, for new comers to ME, like me, you are now going to learn all about the British Standard Cycle thread. 5/8" x 26tpi. Apparently we used to make push bikes and motorcycles for the world back in the Stone Ages!

There is still a lubrication port to add but I am in a dither about whether to use the DY twin mechanically driven pump assembly (which I have the pump parts for) or a displacement lubricator. Oddly DY recommends the latter over the former!

Note to new forum members asking about basic kit for turning and milling. Note the internal telescopic gauge on the compound slide. This one by Starret ( expensive) given to me by my pal who gave me the Harrison lathe. They are brilliant . Get a set. Much better that digital verniers. There are many cheaper ones around.

fullsizeoutput_6fb by Malcolm HARWOOD, on Flickr

That concludes this update but it will not be too long before the next as I have already machined up the valve buckle,balance valve and balance piston.

I have photos and shall report all shortly.

Thanks for reading

regards

Malcolm

[4fbuilder]

Hello Malcolm,

Excellemt work, I admire the clean machines! Another tip for stopping taps hitting the bottom of a blind hole is to fit a little sleve over the tap and keep measuring the protruding tap length until it's fractionally short of the hole depth.

I managed to swipe a 10BA tap in an Eclipse chuck type tap wrench off the bench one afternoon, it stuck in the wooden floor of the workshop and wobbled like an arrow in the Strongbow adverts!

Regards,

Bob

[rrmrd66]

Hi Bob

Thanks for the tip re taps.

I try to keep the mill and the lathe nice and tidy. They are both only just over 12 months old so should look good.

Regards

Malcolm

[rrmrd66]

Good day to everyone

Here follows the latest update on the Hunslet build.

Again it is a bit out of sync' as I do try to get a story/narrative going but inevitably it jumps around a bit.

However let's get on.

First up I continue on with the valve chest.

This requires 18 No. 5BA clearance holes drilled right through. Marking out has been done the traditional way, on a surface plate with a vernier height gauge.

The 6mm ply is to save the embarrassment of drilling into my nice UK made milling vice.

fullsizeoutput_72c by Malcolm HARWOOD, on Flickr

Following that the valve chest is clamped onto the back of the cylinder block and just "spotted through" to mark the position of the 18x5BA stud holes. (See the large clamp and two clamping plates)

Extra care has to be taken not to knock the tap or the Tommy bar in the eclipse chuck when doing the actual tapping of the screw threads. (We don't want to have to repeat the kitchen chemistry experiment with Alum again, do we?)

I attempt to have the top of the tap wrench supported at all times by the crude centre I knocked up from a very old piece of silver steel.

After scratching my head for 10 minutes and to ensure that everything was plumb/clocked level and secure I decided to use the heavy duty adjustable angle plate and various straps and jacks as can be seen.

fullsizeoutput_72d by Malcolm HARWOOD, on Flickr

Within the valve chest there is a valve buckle which is driven by the valve spindles. I had previously faced and machined the outer dimensions to drawing.

Here I am plunge milling up to the line with a slot drill as I found this much faster than milling with an end mill to full depth with light cuts.

A final full depth facing cut was then all that was necessary.

fullsizeoutput_6fd by Malcolm HARWOOD, on Flickr

The valve buckle contains the balance valve. This again doesn't look much but has to be machined all over as well as being bored to accept the balance piston.

Yes don't worry there is sufficient clearance between the top of stud and chuck and I didn't find out the hard way either!

Note the trusty apprentice made parallels.

fullsizeoutput_729 by Malcolm HARWOOD, on Flickr

The balance piston sits in the balance valve. Here it is being turned to drawing.

I am using the casting riser as a chucking spigot which I will remove when I turn the piston in the chuck.

The O ring grove was made with a modified parting off blade with generous corner radii hand ground.

fullsizeoutput_72a by Malcolm HARWOOD, on Flickr

The balance piston if now turned in the chuck. The chucking spigot has been removed and the back faced off.

To protect the turned surface a strip of brass shim (8 thou) is place around the piston body.

The central bore is opened out gradually and finished off to dimension with a boring bar. The fit is tried against the bore in the balance valve.

Don Young specifys, rather airily I think, that a home made18swg bronze wire spring with an effective working height of about 5/16" will have sufficient force to overcome the friction of the O ring on the bottom of the piston

i somehow doubt this. Initial trials are not encouraging. Anybody got any suggestions please?

Did he actually ever build this engine himself? I think something stronger than what he suggests may be needed.

fullsizeoutput_72b by Malcolm HARWOOD, on Flickr

That brings me up to date

Thanks for reading this

Cheers

Malcolm

[jma1009]

Hi Malcolm,

Excellent progress!

The balanced slide valves need only a relatively light spring. You will probably have to make some springs out of phos bronze wire.

Enough to overcome the friction of the 'O' ring and to seal the 'top hat' part of the slide valve sitting steam tight against the steam chest cover, which is open to near enough atmospheric pressure most of the time, and when the regulator is open this part of the balanced slide valve has steam chest steam pressure upon it.

Winding springs for miniature locos out of phos bronze, piano wire, and stainless wire, is quite fun in the lathe, if a bit alarming sometimes!

I don't know what Don specified for these springs - he was generally quite good with springs. If you need anything I can have a look around in 2 boxes - one of springs, and one of phos bronze, piano, and stainless coiled wire.

Cheers,

Julian

[rrmrd66]

Hi Julian

Many thanks for the tip

Cheers

Malcolm

PS Have sent you a PM

[dscott]

Don uses a big spring in the middle!
Someone said that he had used 4 smaller, one in each corner in holes
and had great success! This is what I have done. Easy to adjust!!
David.

[rrmrd66]

Good Evening to all.

Here is the next installment of the build process.

The spring to keep the valve piston pressed against the valve chest cover is, according to DY, to be made from 18swg PBz spring wire.

I achieved this by trapping the wire in the 3 jaw chuck and altering the tension of the wire as it is fed onto the mandrel by the use of  wooden friction strip(s). By tightening the tool post screws up or down the speed of feed can be regulated much better than holding the wire in, for example, stout leather gloves.

The mandrel, I found by experiment, needs to be about 70% of the required ID of the spring due to the spring wire having a natural tendency to spring out when taken from off the mandrel. Turn the chuck by hand. You don't need to do this under power.

fullsizeoutput_76e by Malcolm HARWOOD, on Flickr

As you will know I have misgivings about the actual force such a light spring will exert in trying to overcome the friction introduced by the Viton O ring.

Initial tests are not encouraging. The natural torsional twist in the O ring appears to have a greater effect than the spring itself.

Dave Scott has suggested an alternative and fit four small compression springs into pockets in the valve body under the head of the piston. I will give this mod. some serious thought as long as I can obtain the correct springs. Lee Springs appear to have a huge selection of such tiny springs.

These are the parts that go to make up the balanced valve assembly , minus the guide rods.

fullsizeoutput_777 by Malcolm HARWOOD, on Flickr

Here is the assembled balanced valve assembly.

fullsizeoutput_779 by Malcolm HARWOOD, on Flickr

Turning for  a moment to the piston head itself, I used the casting riser, turned, as a chucking diameter and roughed out the OD of the piston to 1.625" dia.+0.050"

The thread for the piston rod was drilled and tapped and the piston was mounted on to piston rod

fullsizeoutput_76b by Malcolm HARWOOD, on Flickr

The piston and rod were then mounted into the 4 jaw, trued up, faced and turned to finished OD. The rod surface was protected with some brass shim.

The piston ring groove was turned to accept a Clupert type piston ring with the parting off tool.

fullsizeoutput_76c by Malcolm HARWOOD, on Flickr

I was beginning to get on a roll!

I could not resit offering up what finished pieces I had to the frame just to see what it looked like.

The cross head still requires further work and the cross head beams have yet to be positioned and fixed . However I feel real progress is being made at last.

P1010325 by Malcolm HARWOOD, on Flickr

That about it then for this installment

Thanks for reading

Cheers

Malcolm

[stevep]

Tongue in cheek - I think you will find it better with the crosshead turned round the other way!

[rrmrd66]

Hi Steve

This is what my father used to call a sighting shot or siter. (He was in the RA)

I was just using it as a gauge. It has since undergone extensive machining and forming. See my next post.

Did you spot the cheese head screw (temporary until the right ones appear)?

Thanks for your interest

Malcolm

[dscott]

For tapping I built a stand and sliding holder. The tap goes in via gravity
and as Roger says just fingers on the knurled bit!!
Yes they can be bought for roughly £30 from ARC Euro!!!
The base came from the printing department at work!
It is painted Blue of that helps preserve Taps???
David.