Northumbrian Build Thread

[peteh]

Hi Pete,

I thought about a fly cutter today, but I don't own one - yet. Won't be in the shed for a few more days so will consider that option.

Another option would be to mount my milling vice to the lathe faceplate but I worry on -
a) wether I can secure it safely and
b) if I have the swing

The nice thing about this hobby is you set your own pace - Although I know a few people who want me to finish!

[Shawki Shlemon]

A fly cutter is a useful tool , however what is it for ? , if it is for cylinders you can do it on the lathe , see my article
modeleng.proboards.com/index.cgi?board=general&action=display&thread=703
I hope this helps .

[peteh]

Thanks Shawki,

Most interesting and certainly more to think about. There's a;ways more than one way to skin a cat (poor moggie!)

[doubletop]

A useful thread on fly cutters

madmodder.net/index.php?topic=850.0

Many have made their own cutter holders

Pete

[peteh]

Well I have done a little work inbetween trying to stay warm! Hard to do the fine work while your hands are blue

Here is the first cylinder so far. I managed to 'improve' on the square and have now bored the hole. At some point I have to reduce the cylinder ends to the red dashed diameter, but only for the angle between the bore and port faces. Trying to think of a set up to machine these without a rotary table but may just have to hand file. Public Running day at the club tomorrow so will only get an hour or so shed wise if I am lucky. Thinking I should have made the covers first to help in the marking out.

When I was at GLR I was given some red O rings - are these viton for the cylinders - I havn't measured them as I just thought about them now. If so I will need to make a thinner slotting tool as they are way narrower than my parting blade.

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[jma1009]

hi pete,

the cylinders are looking good! i would file to outer profile to your red mark (new 2nd cut file file required!

viton '0' rings arent red they are white. you will need totally smooth bores (try using a pencil eraser on a bored surface and see what happens).

cheers,
julian

[doubletop]

Pete

They're looking good. I bet you are pleased with that?

Those ends just need to be to size'ish, as they'll be getting covers. I think I made a mandrel for the bore and did them in the round table on the mill. Other than that, as Julian says, its a file job. Leave enough for a bit of insulation under the covers, not that I'd imagine it's going to do much.

You're getting there

Pete

[peteh]

Well I didn't get any time in the shed today, but thanks to your answers I can now look forward to some filing. I think I will make up a couple of steel covers and I can then use those as filing buttons. After spending all of summer complaining about the heat it is now the cold doing it's worst to keep me from the shed

I already have two new sets of files - one for steel and one for non-ferous

[Jim]

The use of filing buttons is a great idea Pete. I used them too as a guide when I had to mill the end radiuses on the coupling and connecting rods.
You're making great progress too Pete in spite of the weather.
I'm looking forward to seeing Northumbrian running on air

Jim

[peteh]

Well I have got the second cylinder squared up and sized and have hit a small snag. In the photo you can see two small voids on the port face. The positions of the ports has been marked on and one void is directly on the edge of a steam port.

I was considering spot drilling the voids to clean metal and then silver soldering to refill. Is this a reasonable idea or should I contact the supplier for a new cylinder casting?

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[doubletop]

Right or wrong I would have tried that. But I'd also be thinking that there was a possibility the heat could distort the machined casting so I'd be on the phone to get a replacement sent out.

Pete

[arch1947]

G'Dat Pete, Hope it is warmer in WA than it is in sunny Tassie. I am not sure about the wearing qualities of silver solder compared with the cylinder material, similar I would think (other on this forum will know better than I) but you don't want to produce a hard spot. You could drill the void out and silver solder a round plug in of the same material as the block, maybe drill and tap and screw a piece in then silver solder. If the void is not too deep, can you machine the vlave face down more and compensate in some other area?
Good luck,
Arch

[Jim]

Another possibility following on Arch's suggestion would be to machine the face down to eliminate the void then replace with a brass plate to bring the face back up to size. The plate could be secured with c/s brass screws. If you were worried about leakage under the plate I'd tin the under side and matching face of the steam chest then sweat the two together and secure with c/s brass screws if you thought they were needed. When finished lap it all to get a nice true surface as per the original.
Just another thought.

Jim

[jma1009]

i would agree with Jim's suggestion, soft soldering a pice of 1/8" brass plate to the steam chest after machining the cavities and passageways in the cylinder casting. the brass plate can have the ports cut to size before soft soldering and add a bit more soft solder around the bridges to ensure no gaps in the soft solder between exhaust and steam ports/cavities.

cheers,
julian

[arch1947]

Hi Pete, The idea of machining the void out is good. I had trouble getting the ports right on Virginia and finished up machining a shallow cavity a little bigger than the area covered by the ports and larger than the swept area of the valve and then made up an insert with the ports cut to the correct size. The insert is secured by countersunk, stainless socket heads and it works fine. If I remember correctly I didn't bother with any seal under the inserts but soft solder sounds like a good idea.
Cheers,
Arch

[peteh]

Thanks for all of the replies guys. I was up at the club this morning and asked some of the more knowledgable guys there. I have been told by a member (professional engineer) that he has some solder paste made just for casting porosity, so he will bring some to the next club meeting (much quicker than waiting for another mail out from the UK).

I was also concerned about distorting the bore but this is a high temp soft solder from what I can gather - mucher lower melting temp than silver solder.

After the birthday party at the club it's now time for another party at home - my son turns 18 today so there won't be any shedding !

[Shawki Shlemon]

One of my engines was built from a set of castings that were some partially machined by some other person , one of the cylinder blocks the valve face was over machined , the bores were OK , I silver soldered a piece of bronze ( not brass ) and re-machined , it worked fine , the engine runs well . It can be done , of-course the other methods mentioned will also work , it depends on the size and depth of the fault .

[steam4ian]

G'day Pete

Regarding high melting point solder which others have recommended. You should be able to get it in Perth from Altronics.

I got some from them in Adelaide, its called Multicore Alloy HMP Type 5C Ersin 362. Melts at 301 degC.

I have two letters from the AMSB committee saying I can seal a leak in a boiler tube plate with it. The secretary even suggested I could use it to soldering in bushes!

I am not sure about getting bronze sheet, see Shawki's comment, but depending on what your slide is made of brass should be OK.

PM me your address and I will send you some if you can't get it quicker elsewhere.

Regards
Ian

[Jim]

Thanks for the information re the multi core alloy Ian, I shall see if I can source it locally here.

Jim

[peteh]

Thanks for the offer Ian,

As it happens I am a frequent visitor to Altronics - one of my other hobbies being electronics.

Pete