Northumbrian Build Thread

[peteh]

Hi Pete,

Will try and get some photos in the next cople of days, busy on my wifes stuff tonight. The jig (above the table) is not as long as the cylinder. The real solution is a larger mill, which I am hoping to get in the distant future, although that is dependant on getting the Northumbrian working!. I can't get to my club on the machining days though they do have a mill there. My thoughts at the moment are leaning towards a compound table - unfortunately the things are bl**dy heavy so will probably have to buy local.
Local machinery shop has a sale between 15th and 17th November and can save more than the GST so may be worth waiting for - also my wife will be away so won't see what I'm buying Ideally I would like to be able to drill and tap while set up, ensuring square threads.

Later,

Pete

[steam4ian]

G'day Pete

If your drill is a really good one, no run out, no quill movement then a good quality compound table is most likely worth the money.

I have one of those cheapies which helps me chase the drill! I suppose I could fettle it to make it better.

I suppose you have stripped down you jig. For me I would have made a drilling jig out of a steel disc for the tapping holes in the cylinders rather than drill through the cylinder covers and risk , well you know what when things slip.

Regards
Ian

[jma1009]

pete,
i have never bothered indexing holes for cylinder cover bolts. the covers only fit on the cylinders in one position due to the chamfer/recess for steam admission/exit alongside the passageways, so why bother with indexing? i mark them all out carefully, drill the covers tapping size, then spot through the covers into the cylinders. the first one i do i then drill the cylinder and tap same with the cover removed, and open out the cover at that position to clearance size for the first bolt or stud. i then work my way round. the less jigs i have to make the better.
go carefully when tapping gunmetal! it doesnt like a tight tapping size or blind holes unless cleared of swarf/tapped thread dross! frequently clean the taps and the hole. also note that if the holes are too close to the bore the gunmetal may 'bulge' locally on the bore. if you have a piece of bar you can turn down to a tight piston fit into the bores to prevent this bulge whilst you drill and tap the cylinder ends then much extra work is saved!
for small cylinders such as yours i would hold same on the pillar drill table for drilling rather than in a vice and let the work find its own centre on the drill as it revolves. taking the edge off the drill bit removing the negative rake such as you would do for brass can be recommended for gunmetal too. frequent be-burring is required during the above operations, as well as cleaning the holes in the cylinder block of swarf. i never drill the covers clearance size then spot through clearance size into the block, but as stated above drill tapping size opening out the holes in the covers to clearance size after drilling the holes in the block. before tapping same i provide a lead 1/32" deep clearance size dia on the tapping size holes in the block (set the depth stop on the quill for this). gunmetal can be funny stuff sometimes!
i tap the holes holding the tap in a round file type handle with a screw chuck and holding the block in my hand (to avoid tap breakage - which is the last thing you want at this stage!).
as you will gather, the frequent cleaning of the holes and drill changing etc.. make the practicality of doing all this on a rotary table difficult anyway.
i hope my method is of interest.
good luck! you are making excellent progress!
cheers,
julian

[peteh]

Thanks Ian and Julian
More to think about. I think I stated that I drilled tapping size for the covers - as how can you accurately drill through if your holes are effectively oversize for the next operation.
Pete

[ilvaporista]

A tip given to me is to make cylinder covers with the bolting holes already finished from the lathe.
I do not have a handy picture of my set up on the larger lathes but attached is how it's done on a Unimat SL.

For my larger lathes I made up a simple angle plate which bolts in place of the tool holder which I bored directly in the lathe at centre height with the 43mm dia hole to mount a standard electric power drill. A horizontal slot was sawn through from the side and a clamp bolt made to close the 43mm hole around the drill collar.

Obviously it's not a set up for doing this continuously but it puts all holes on the same PCD. Don't go mad with the feed in (which I usually do with the carriage hand wheel to speed things up).

Coupled to some form of dividing system (This is where the Atlas scores as it has 60 holes drilled in the larger of the back gears with a detent pin) you can make perfect covers finished directly in the lathe without having to set up the rotary table and re-find the centre.

Also used for radial holes by swinging the angle plate round with the drill axis perpendicular to the lathe axis.

On the Colchester I use a detent finger in the gear that transmits the drive to the leadscrew. For other division numbers I print a paper scale off on the computer and stick it round the chuck body (using Pritt type glue on a clean surface) and line it up with a a scriber held in a magnetic stand secured on the bed.

These paper division scales are quite easy to make on the computer and when they get dirty or ripped just print another one. It took a while to get the right length strip for my chuck but once done I can print a few and keep them handy.

On the smaller machines I have used my Dremel style tool in a similar way and on the very small Unimat a system was rigged up with a flexible drive as shown on the picture. Here it is being used perpendicular to make bosses for the handwheels on a G1 loco. Although this job uses the SL dividing head you can see the dividing arrangement on the headstock and the paper scales for divisions. The red part is a gear selector from a Morris Minor gearbox reused as a support for the detent finger.
I hope that gives some ideas and is of use to anyone else thinking about this type of work.

Edit: I should point out that the Unimat is treadle powered before anyone commnets on open belts, this comes from being too mean to replace the dud electric motor. It's used mostly for G1 but it did turn the smokebox dart for a 7 1/4" Highlander.

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[peteh]

Thanks ilvaporista,
More good ideas to cogitate.

[peteh]

For Doubletop's eddification here is a photo of the rotary table placed on the mill table. - not enough room to chage bits at all. Little bit more room than I remembered however.

I have decided to go for clamping the cylinders direct to the mill table and then set up for each hole - there's only 24 of them

I also have to file the gland/guide bar protusion to final size but will make a template up first to ensure simularity.

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[doubletop]

Pete

Thanks for the picture but I was hoping to see how you mounted the round table to the cross slide. Is there any way, say with an angle plate you could hang it off the side of the topslide? Making the top of the round table chuck about the same height as the top of the topslide?

Anyway you seem to have solution.

Regards

Pete

[peteh]

Hi Pete,
There isn't room for that as the lathe beds are too high in relation to the mill table. The rotary table in the photo is sitting on the mill table, just not bolted down

1st 6 holes drilled and tapped now so should finish the rest over the weekend.

Pete

[peteh]

Another quick update (sorry no photo) to say that the covers & cylinders are all drilled and tapped. Very happy as there is no discernable extra drag on the piston rods .
I have now started on a jig to finalise the shape of the cylinder gland bosses, which will ensure they are both identical and symetrical. Looks like tomorrow will be lots of filing.

[peteh]

Filing jig was finished this morning followed by a couple of hours of filing. The gland bosses now look much better and identical

Next job was cutting the 8BA bolts to length, 24 for the covers and a further 10 for the steam chests. I buy all of my bolts in a single length and then cut to size. The exhaust flanges will need studs in the cylinder block.

Doubletop - did you put O-rings beneath the exhaust flanges? - seems to me this might be an easy way to ensure they seal - just counter bore the exhast area and slip an O-ring in with say 0.1mm proud and nip up the nuts. Maybe I'm just thinking of making work for myself.

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[doubletop]

Pete

Great job there and I bet you are pleased to have got that over with? Too many opportunities for a stuff up during that phase. Must be getting very close to air time?

No I didn't put O rings under the exhaust flanges. I hadn't really thought about it and I just used a thin smear of silicon gasket. There's next to no pressure at that point so you are only really sealing against leakage of condensate or oil from over lubrication.

While I'm here are you doing a superheated version or not? I'm guessing not, given the position of your inlet union.


Pete

[peteh]

Hi Pte,
Thanks for the feedback. Most glad that is over. I played safe and did the tapping while holding the cylinders in my hand - much more feel for when you have bottomed out. I'm obviously trying to outsmart myself and make work! Looking at your thread it looks like there is a small overlap of the exhaust flange over the edge of the steam chest, but could be just the angle of the photos.

I have the materials for the superheaters but do wonder if it will contribute much to this engine. The inlets are off centre by 1/16" so there should be room. Also trying to work out wether I am going to be a masochist (sp?) and coal fire or gas!

I think I heard that in the new boiler code released earlier this year that girder crown stays are no longer allowed - will have to clarify tht with the boiler inspecters.

[steam4ian]

G'day Pete

LBSC put superheaters in all/most of his locos, even Tich! There must be some merit.
Barry Potter did not put superheaters in Blowfly, but as far as i know has recommended two boiler/firebox upgrades to get more fire and steam. I think that says something. Even if the superheater only dries the steam that has to be some value.

Cylinder and pipe losses don't scale but proportionally increase with smaller sizes, all the more need for raising the steam temperature.

One wonders how Sweat Pea would go with superheat and good valve gear? Not saying both Sweat Pea and Blowfly are not established performers just that improvements might be possible.

I have also heard that girder stays are out for the AMSB Code, the former Code revision did not "like" them..

Regards
Ian

[jma1009]

pete,
do please fit superheaters. the extra work involved is well worthwhile whatever size of loco. from a theoretical standpoint you gain better flow of steam in the steam circuit, and if the valvegear is ok you gain from proper efficiency and expansion of the steam (though i recall you have slip eccentrics which is rather a shame). you will also obtain reduced coal and water consumption... a result of increased efficiency due to 'better quality steam' in the cylinders, and easier driving as a result.
do please use coal! a steam loco isnt a steam loco unless fired on coal! (though until the late 1850's steam locos used coke!). Northumbrian in fullsize would probably have burned coke!
cheers,
julian

[doubletop]

Nov 12, 2012 11:05:29 GMT peteh said:

............. Looking at your thread it looks like there is a small overlap of the exhaust flange over the edge of the steam chest, but could be just the angle of the photos.

It was probably a photo of one of my trial fits. I had done a few by the time I'd finished. I've just wandered over to take a look and no overlap on either side.

I won't get into the gas vs coal debate but I run mine on gas as it is very convenient to get set up run and pack up at the end. But it would be easy to do both, pulling the pin and dropping the burner and jet assembly and installing the ash pan wouldn't take more than 2-3 mins.

Pete

[peteh]

Thanks for the feed back gents. Nothing done today as we had a medical emergency - my Sister-in-law had a fall and is back in hospital with a broken ankle, after finally escaping from an on/off 2 year period in hospital with an infected broken leg! We provide transport to my Mother-in-law so we spent a while visiting and then catching up on the domestic chores

[peteh]

Chaotic week - Sister-in-law in hospital and wife, daughter and Mother-in-law away for a week, so I am having to commute daily to my M-I-L's house to look after her pets, then come back and do the same for my daugthers! Needless to say the Northumbrian has been suffering from neglet.

Finally today I managed a few extra hours and started to put the guide bars, cross head and guide bar brackets together. The penalty of trying to make these parts early on has come round and bitten me. Both crossheads were majorly out (around 0.25mm) so I had to make new ones. Both brackets were also slightly out but these were fitted with the benifit of a jewellers round file as the error was less than 0.1mm. My guess is that the errors crept in by not taking into account the backlash on the cross feed. Nowadays I set up a dial indicator and follow that.

Yesterday was Hare and Forbes sale weekend last day and our club assists with the sausage sizzle and provides a few models to be looked at. Needless to say some new equipment has found it's way back to my place - and without my wife knowing

Very nearly broke down and got a Super X3 mill but don't have anywhere to put it at the moment, so instead commiserated with a nice chuck for my rotary table, an electric drill sharpener and a few other bits and bobs.

The girls aren't back until Thurday so doubt I will get anythin done now until next weekend.

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[peteh]

Annoying weekend this week - away for most of it and only managed to snatch 90 minutes or so. However I still managed to run into a possible snag. I have made a piston rod extension to help set up the cylinder CL and found that the text was stating 9/16" at the axle from the frame bottom while the plan showed 1/2"! I realise that there is the suspension travel in this but which should I be using?

Please see attached images.

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[peteh]

Text

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