WW1 Dennis truck find

[mammoth]

A vet that does cattle AI will have liquid nitrogen to sell and a container to hire.

[David Herbert]

I have always wondered how to get hold of liquid Nitrogen as it is a really good way to shrink parts that would otherwise have to be pressed into holes with an interference fit. Do you have any idea what a reasionable charge is for 'borrowing' what one would need? Also I suspect that the safety aspects must be taken quite seriously which might be a problem. Someone here must have experience of this.

 

David

Edited November 13, 2013 by David Herbert
missprunt

[Tony B]

Have you thought of water pipe freezing kits? These come complete with all parts and gas can be replaced easily. Though not cheap http://www.screwfix.com/p/pipe-freezing-kit-220ml/13369 Actually a quick search, £17.99 not as expensive as some I've seen.

Edited November 13, 2013 by Tony B

[Chris Suslowicz]

I would have though a "cork borer" would be what you needed!

 

I remember these from Chemistry, "Lo! these many years ago" and they were thin wall brass tube sharpened at one end and with a 'T' handle on the other. You just screwed them gently through the cork (using water as a lubricant) for running glass tubes through.

 

These days it's all ground-glass QuikFit joints, of course.

 

I suspect that to make a sleeve you'd need to get the borers mounted exactly concentric and proceed very slowly using a fine-grained bit of cork.

 

Chris.

 

See: http://www.rapidonline.com/education/cork-borer-sets-78937/

[Chris Suslowicz]

Some thoughts on how to proceed:

 

1) make up a mandrel the diameter of the valve inner but rather longer.

2) make a cork borer (thinwall tube with inside diameter the same as OD of the mandrel)

3) find a thick piece of suitable cork and bore a hole using (2).

4) make a second cork borer to match the bore of the hole in the valve body.

5) fit the chunk of cork to your mandrel and centre it in the lathe (possibly tailstock best)

6) fit the second borer in the lathe chuck and centre that.

7) "advance to contact" using the lathe as a press, (pulling the belt by hand) slowly cut the sleeve to size.

8) remove cork sleeve from borer and mandrel, trim to required length and fit to valve.

 

I suspect this was the method used for the original manufacture.

 

Alternatively:

 

1) Glue a slightly oversize block of cork to a block of wood.

2) cut the outside first

 

:mad:there was more of this but the ba*d system said I wasn't logged on when I submitted the reply and the rest is gone.

 

Consider wine or belgian beer corks as a source of raw material!

 

Chris.

[8_10 Brass Cleaner]

Some thoughts on how to proceed:

 

1) make up a mandrel the diameter of the valve inner but rather longer.

2) make a cork borer (thinwall tube with inside diameter the same as OD of the mandrel)

3) find a thick piece of suitable cork and bore a hole using (2).

4) make a second cork borer to match the bore of the hole in the valve body.

5) fit the chunk of cork to your mandrel and centre it in the lathe (possibly tailstock best)

6) fit the second borer in the lathe chuck and centre that.

7) "advance to contact" using the lathe as a press, (pulling the belt by hand) slowly cut the sleeve to size.

8) remove cork sleeve from borer and mandrel, trim to required length and fit to valve.

 

I suspect this was the method used for the original manufacture.

 

Alternatively:

 

1) Glue a slightly oversize block of cork to a block of wood.

2) cut the outside first

 

:mad:there was more of this but the ba*d system said I wasn't logged on when I submitted the reply and the rest is gone.

 

Consider wine or belgian beer corks as a source of raw material!

 

Chris.

 

 

Strikes me the simplest way of sorting the job is to remachine the existing (pre petrol soaked - and thus pre - expanded) PTFE to the same dimension you started with.

 

Presumably it would seal just as well as it did when new, and it should be unlikely to grow any further causing more problems with binding.

[Old Bill]

Thanks for all the ideas Chaps. I will let you know how I get on!

 

Steve

[mammoth]

Handling liquid nitrogen - I used it for freeze branding (the hair grows white and doesn't present the animal welfare issues as with fire branding). Pour the liquid from the flask into a container, eg a lunch box which is nestled with polystyrene packing in a larger container, and which has a lid to slow down evaporation. There will be a bit of bubbling as the container cools down. The item to be cooled has to be got out so either tie wire to it or use long thin tongs. Wear gloves and goggle as if you were dealing with molten metal. As you lower it the liquid will boil and once this has stopped it is ready. Don't drop it in otherwise you risk cracking the luch box!

[andypugh]

Also I suspect that the safety aspects must be taken quite seriously which might be a problem. Someone here must have experience of this.

 

There is some danger of asphyxiation if using it in a confined space, but other than that it is actually significantly less dangerous than boiling water.

It always used to amuse me that we put on a load of equipment to handle LN2 then took it all off again to boil a kettle.

 

Now, the mixture of LN2, Bromine and Methanol, that wasn't at all nice.

[flandersflyer]

Thanks for that. Always useful to know who can do these sort of jobs.

 

Tony has now made the oil scoop and the locking nut.

 

 

Proper job!

 

We have the correct bearings (thanks Chris) so we just need to arrange a day when all of us can get down to Devon to put the thing back together. It is going to be a busy day. Then what is it next chaps? Water pump or torque tube?

 

Tim (too)

i would imagine the original part would have been made by using an adjustable broach...with multiple cutting faces to suit the form required...this could be mounted in a slotter...the idea being that on the upstroke (after each cut was taken)...the broach could be `indexed` to a slightly larger diameter using a similar idea as how an adjustable reamer works by means of the machines auto indexing...until the component comes out `size`....

[Old Bill]

That would be interesting to see. We had a slotter at work but it was scrapped a few years ago (it was marked 'War Finish'!). I never saw it in action. I worked at Aveling Barford for a while and they splined gears by pulling a single long broach through. Long means over ten feet! I never saw that in action but the tooling was all stored around it.

 

Steve

[Cel]

The single long broach is still common practice. I have an old Butler slotting machine, made in Halifax. With the right broach and a dividing head it would be no problem to make the splines. Will have to do that in the near future and let you know how I get on with it! Marcel

[Minesweeper]

The Historic Commercial Vehicle Society organise a London to Brighton Run each year on the first Sunday in May. Next year, they have included a Special Class to mark the commemoration of the start of World War One and have invited their members' vehicles from the WW1 era, especially military vehicles and those derived from the Subsidy Scheme up to 1920 to be entered.We have entered the Dennis and understand that several other military vehicles from the same period will be running. Tony

[Charawacky]

Hello Tony

 

Can you tell me what time did you elect to set off, Early, Middle or Late?

Perhaps a convoy this time if we get the timing right.

The Crossley will be much slower with the un-braked trailer.

I have changed the axle gearing crown wheel and pinion for a lower ratio to cope with the extra weight!

May also have sorted a fuselage.

 

I await your timing response before submitting my entry.

 

Tom

[Minesweeper]

Hello Tony

 

Can you tell me what time did you elect to set off, Early, Middle or Late?

Perhaps a convoy this time if we get the timing right.

The Crossley will be much slower with the un-braked trailer.

I have changed the axle gearing crown wheel and pinion for a lower ratio to cope with the extra weight!

May also have sorted a fuselage.

 

I await your timing response before submitting my entry.

 

Tom

 

We have gone for "early", Tom - I think that we will need as much time as possible to get there before the stipulated deadline. To the best of our knowledge at the moment, we think that there will be at least another three 3-tonners who intend to enter and that is not counting the Grundon's Pierce Arrow. Should be a good show! Tony

[andypugh]

The single long broach is still common practice. I have an old Butler slotting machine, made in Halifax. With the right broach and a dividing head it would be no problem to make the splines. Will have to do that in the near future and let you know how I get on with it! Marcel

 

Practically speaking this is nowadays a job that might be passed on to a wire spark eroder.

 

I recall back before the turn of the century that David Brown's of Huddersfield (still probably the premier gear maker in the world) offered to make a set of gears for the 1916 Fire Engine operated by Imperial College. It is pure coincidence, of course, that at the time I was a student there and my dad was a manager there :-).

 

Anyway, they made an "at cost" quote of £400 then found that the gears had a 5-spline hole in the middle. (in 1916 5 splines was seen as "almost metric". 10 was in, 6 was out, 5 was more like 10. (I am not kidding)).

 

They ended up paying £600 for the spline broach.

 

Anyway, I am not at all sure that you can index a broach. You can definitely index a slotter (as the tool is self-guiding) and you can press a shaper and rotary table in to service as an indexing slotter (I have, Dennis "Box Joints")) but I can't see the typical keyway broaching machine indexing very well at all.

 

<thinks>

 

Actually, with a guide bush that indexes to the first slot for slots 1+ then it would probably work fine.

[Old Bill]

With Brighton getting close again, I thought it was time I did some work on our own lorry! I have, therefore, been looking at the fuel tap issue once again.

 

Whilst rummaging in a box of bits, I found this tap which I had forgotten about.

 

 

It was obviously designed for a cork sleeve but this is missing so my thoughts turned once again to the challenge of machining cork. I found a cork which I held gently in the three-jaw and drilled through at 3/8" diameter, very gently at high speed. This was successful.

 

 

 

The outside diameter presented more of a challenge.Many years ago, a dear friend had suggested that cork and rubber could be machined using a grinding process. I therefore set my Dremel pencil grinder up in the toolpost of the lathe with a grinding disc and pushed the cork sleeve onto a piece of bar held in the chuck.

 

 

With the lathe running at 300 rpm and taking 0.005" cuts, I ground the surface with this result.

 

 

It quickly became apparent that some dust extraction might be advisable! I did try heavier cuts but the wheel soon clogged so I stuck with five thou until the body of the tap pushed on.

 

 

 

After removing the sleeve, I cut a couple of notches with the Stanly knife to engage with the drive dogs and then assembled with a drop of oil. A quick poke through with a drill to give the 'open' position and Bingo!

 

 

 

 

The task for this morning is to put the correct threads on the tap to suit the lorry. One question remains, however. The cork is reconstituted crumb so will it survive without breaking up? I know it is alcohol resistant (!) but what about petrol? No doubt we will find out in due course!

 

Steve

[MatchFuzee]

If you have another piece of the same type of reconstituted cork, have you thought of soaking it in petrol to see how resistant it is? If it is resistant the cork should last in the tap and if not it will give you chance to find a replacement material.

[Old Bill]

Good thinking! I will go and syphon some petrol.

 

Yesterday, I carried on and finished the tap. First, I turned up two sleeves with a 5/8" BSF thread.

 

 

Then I turned the old thread off.

 

 

 

Silver soldered the sleeves.

 

 

A good clean up and it is ready to fit (pending cork trials of course!)

 

[Thumpercross85]

The issue will be whether the binder that has been used to reconstitute your particular bit of cork will survive the fuel exposure, and modern fuels have all sorts of additives that give traditional rubbers a problem. If you arent sure of the heritage of the cork a soak test is essential as it could literally disintegrate. We have 20mm thick nitrile bonded cork in stock, but having had an issue with modern pump fuel attacking a cork filler cap gasket I made for a friends Metisse recently, it turned out that once again, the right spec of Viton rubber was the answer...

Edited March 23, 2014 by Marmite!!
Quote removed

[Old Bill]

Ok, I will make a point of it. The thought of losing 30 gallons of fuel in the road rather frightens me! I also have in stock, an ordinary old fashioned cork cut from a single piece. I think I will try making one up from that whilst I still have the procedure in mind and the tools on the bench.

 

Steve

[andypugh]

I also have in stock, an ordinary old fashioned cork cut from a single piece.

 

I think that would be a better bet, and more original too. Crumbs of cork in the fuel system could quickly become annoying.

 

A lump of PTFE might be a good (and less original) alternative.

[GeePig]

A lump of PTFE might be a good (and less original) alternative.

 

I disagree, a full study of cork products based on extensive testing of suitable vintner's produce would be far more appropriate.

[Old Bill]

A lump of PTFE might be a good (and less original) alternative.

 

Hi Andy.

 

It was PTFE which started me on the cork trail in the first place! Sarah, one of the Jezebel crew, kindly pointed out that PTFE swells in petrol which is why the original tap jammed up. I am hoping still to be able to open it when we go to recover the Dennis from storage prior to the Brighton run.

 

Steve

[andypugh]

It was PTFE which started me on the cork trail in the first place! Sarah, one of the Jezebel crew, kindly pointed out that PTFE swells in petrol

 

I will bow to her experience if it was one of the Sarah the Chemists, rather than Sarah the Mathematician. :-)

http://www.dkirubber.com/materials.asp says that "fluorocarbon" is resistant to swelling in gasoline, but doesn't make the same claim for PTFE, (which I thought was a fluorocarbon)