WW1 Thornycroft restoration

[alixcompo]

While it may not be such an authentic solution, why not use a modern aditive such as 'K Seal' in the cooling system once the engine is running.

Whilst not specifically endorsing it, this product will seal a leaking head gasket so I'm sure it would plug pin holes and any other part of the system which might have become porous.

[Tharper]

Wonderful repair! I almost had to do a similar repair to the water pump on my Wisconsin. As with your Thorney the neck was broken-off. As luck would have it I found a complete original.

 

In regards to your pattern: Top notch work! I cheat on the core boxes. I fabricate a male master and cast the core box itself out of plaster of paris. They are not as durable as a wood core box but if they get damaged its easy enough to cast a new one.

 

The miss-alignment looks like an issue with the flasks not indexing correctly.

 

[Old Bill]

Thanks for that but your core boxes put mine to shame! They are a work of art in their own right. I hadn't thought about casting in plaster but that might just be the way out for the onion shaped fan support casting that we will have to make shortly. The core for that one is still causing me to scratch my head.

 

From the photo, it looks that you made the male in two pieces and mounted each half on a board. How did you maintain the alignments so that the core didn't have a witness line along its length? Come to think of it, how did you make the male parts at all? I can turn a straight cylinder but a long bent one I would find quite a challenge! Please would you post a step-by step explanation of the process you used for this one as whilst it looks a simple shape, it certainly isn't and I would love to know!

 

Cheers!

 

Steve :cheesy:

[Old Bill]

While it may not be such an authentic solution, why not use a modern aditive such as 'K Seal' in the cooling system once the engine is running.

 

Hi Alix.

 

Thanks for that suggestion. Yes I have heard good things about K-Seal and I think it might well be the final solution. At the moment, one of the leaks is quite severe and it will be simple enough to have another go with the welder. However, the small ones are not worth getting it all hot again so the plan is to suck the air out and paint it with Loctite to try to draw it into the holes. If it still leaks here when we run it, we will add the K-Seal to the radiator as there will undoubtably be leaks elsewhere in the system as well. One thing we have learned about these old lorries is that if they stop leaking, it is because they are empty!

 

Steve:cheesy:

[David Herbert]

Come to think of it, how did you make the male parts at all? I can turn a straight cylinder but a long bent one I would find quite a challenge!

 

I think he used a Pattern Makers lathe. They have a flexible section in the bed that you set to the radius that you want. If turning a small radius bent cylinder you have to keep the speed down or it will thrash about a bit.

 

Hope this helps

 

David

[Tharper]

Hello Steve,

 

Remember I have only been at this a short time and I am self taught so what I do my not be the easist or best but here it goes:

 

To get the elbows I make a simple turning on the lathe - this is nothing more than an old (1942) 13" South Bend.

Basicly all your doing is turning a ring that represents ...well... half of a bagle. I glue brown craft paper between the quarters (partlines) so they can easily be broken apart after turning. This is a neat trick that I use on all my patterns..It beats using screws etc. or having to saw them.

 

Once the piece is glued-up I mount it on a face plate - I use a sacraficial piece of MDF bolted to the face plate. Screws from behind hold the piece to the MDF. Its important that the intersection of the partlines is centered and that the screws secure each quarter securely to the MDF.

 

Nexts its time to rough out to the outside diameter and bore the center hole. Once this is done I cut 45 degree facets so in cross section it half an octagon.

 

Next I take sand paper and round it all off. I use a template to ensure a round cross section.

 

Once done remove from the face plate, split at the part lines (the paper laminated between makes it easy) - match two quarters together and there is your elbow!

 

 

 

 

 

 

In regards to the cores: Once the core boxes are filled with the core sand mix they simply turn them out on a steel plate - the vent is cut and they are cured. Once cured they glue the halves together and insert into the core prints. In some cases Chapletts are need to keep the core from floating or shifting.

 

I hope this helps!

[Old Bill]

I think he used a Pattern Makers lathe. They have a flexible section in the bed that you set to the radius that you want. If turning a small radius bent cylinder you have to keep the speed down or it will thrash about a bit.

 

David

 

Thanks David. I don't quite understand but will have a look at Google and see if I can find some pics.

 

Cheers!

 

Steve

[Old Bill]

Hello Steve,

 

Remember I have only been at this a short time.......... Once cured they glue the halves together and insert into the core prints. In some cases Chapletts are need to keep the core from floating or shifting.

 

I hope this helps!

 

Ah, so that is how you do it! You make the core in two pieces and glue it together afterwards. The light is blinding! Easy when you know how!

 

Your turning of the elbows is impressive too as the circular section relies on your skill rather than the rotation of the part. Because they are turned at the same time, the two halves of the elbow match exactly for width and section. Sooner or later, I am going to have to treat myself to a larger woodworking lathe as with only a 3 1/2" centre height to play with, I don't have the capacity to do what you have done but at least I know how, now!

 

Many thanks,

 

Steve :-D

[Tharper]

Glad I could help Steve!

 

Yes the core is formed in two pieces and glued together with PVA (Elmers Glue over here).

 

Here are some cores assembled and ready to be placed. Note the vent hole in the end of the core on the far left. This is just a shallow groove running the length of the core.

 

 

Another good trick is using a follower. This is nothing more than a block that holds the pattern in proper orientation so it can be pulled cleanly and avoid a lot of digging to get to the part line of an odd shaped piece. In this instance I had to use a four part pattern and a follower. Once the pattern and follower have been rammed-up the follower is removed and the other pieces to the pattern placed. Then the other half of the mold is rammed-up. After splitting the cope and drag the pieces can be removed - first the flange then the tee section. Any ridge left where the joint is can be dressed-down prior to casting.

 

 

Again I think the work you are doing is wonderful! Just an FYI...if you need any etched plates for this project let me know. I have had to dabble in that a bit too!!

 

[Asciidv]

I know that this is Steve's Thorneycroft thread, but I am sure he will not mind if I ask you a couple of questions which your very interesting pictures raise. First are you casting these parts yourself in your garden!? The internet has many examples of 'home foundries' but they tend to be more for model parts or decorative plaques not large manifolds. If your are casting these parts I think we would all like to see some pictures of your furnace and perhaps the actual pouring.

 

My second question relates to your etched plates. I too have made etched plates for my Dennis Fire Engines, but I always find the black infill a problem. After etching the brass I then use a brass blacking solution which is applied all over. I then polish this off the un-etched sections leaving the black in the lower level of etched brass. This can be tricky. What is your equivalent of plaster of paris core boxes for your plates!?

 

Best wishes,

 

Barry

Edited February 21, 2013 by Asciidv

[Tharper]

Hello Barry,

 

I will be brief because I don't want to steal Steve's thread and...I want to see more of the work on the Thorney!

 

Anyway... yes the foundry is a homemade backyard/partime commercial setup run by my friend Peter Grant of Odd Duck Foundry. He started it as a hobby but now cast parts for nuts like me that the big foundries wont take on. He can do alum. Brass, bronze and Iron. The furnace is powered by waste oil.

 

Most of the pieces he has cast for me are bronze.

 

 

Here is the result: This is the assembly for the upper water manifold. The pipe is 1-1/2 diameter". We have also cast the components for the bronze intake manifold which, as per the original, is a built-up component. I have yet to finish machining the castings.

 

The only limit to what Peter can cast is his crucible size.

 

 

In regards to the plates. I use spray can automotive enamel. Once cured I wet sand with fine wet/dry paper wrapped around a smooth piece of wood. Use no pressure...just let the paper do the work. I also add a bit of dish soap to the water.

 

 

 

NOW BACK TO THE THRONEY! I NEED MY DAILY FIX!

Edited February 21, 2013 by Tharper

[Minesweeper]

Really wonderful enterprising work with impressive results - well done!

 

Tony

[Old Bill]

That is a beautiful plate. The letters are all so crisp too. Wonderful work!

 

I think we are going to have to have a go at this backyard foundry stuff. Something else to ponder.......

 

Don't worry about hijacking the thread. I think of this as a bunch of friends sitting in a pub having a good old natter and whilst we have common interests, the topics can ramble into all sorts of interesting corners!

 

Steve:-D

[Old Bill]

Glad I could help Steve!

 

Hi Tharper!

 

I have been admiring your exquisite patterns again. They really are beautiful. What sort of timber do you use? Also, how did you put the blank together for the elbows? Can I see three layers put together in small segments?

 

I use MDF as it is easy to work and good enough for the few castings I want. Not nearly as pretty as yours though!

 

All the best,

 

Steve

[Tharper]

Hello Steve,

 

Sorry to take so long to reply. I use Pine for the patterns. Its cheap and is easy to work with. Pine use to be very popular in the old pattern shops. You could also use Cherry or Mahogany but I find both too costly. I had one Mahogany pattern that was professionally made. Unfortunatly they did not fill the grain so when the pieces were cast using Petro-bond sand the castings picked-up the nicest wood grain!

 

Yes, the blank is made up with three layers. The bottom and top layers each have 8 wedges (2 wedges per quarter). The middle layer is made from 12 wedges (3 per quarter) This provides overlaps of the glue joints and a bit of extra strength.

 

I seal the patterns with a coat of shellac then prime and paint with automotive enamel from spray cans.

 

Another trick is using pinned or removable pieces in your core boxes and patterns. Its a great way to deal with the odd item that projects from the piece and could make life dificult.

 

Below is the pattern and core box I made for the oil pump drive housing - to the left are the remnants of the original. The orange disk visible on the inside of the core box is a for the rased boss that acts as the thrust bearing on the finished casting. Once the core box has been filled a pin is removed and the disk slides out with the core.

 

 

 

 

 

Here is the core fresh out of the core box. You can see the disk still in place. It will be removed and the core baked.

 

 

Here you can see the core in place and the impression left by the removable disk - this will form the rased boss for the thrust bearing.

 

 

 

 

And.... the finished casting bolted-up for a trial fit.

 

I hope this helps!

 

Best regards,

 

Terry

[David Herbert]

Terry,

 

As far as I can see the core of your oil pump drive casting is not positively fixed in the mold. Is that true and so what holds it from moving? It obviously cast ok but I can't see how!

 

I think that one thing that makes your patterns look so good is the precission of the joints. I presume that you machine cut the individual pieces as far as you can and use very well seasioned timber so it doesn't move after it has been cut. Your attention to detail is quite inspiring, I think you should have your own thread called: How to do things that other people aspire to, and really well. The etched plates are beautiful too.

 

When you have the engine done, will you be making the rest of the Lombard tractor to go with it or will it be an exhibit in its own rite?

 

David

[Tharper]

Hello David,

 

That would be a very short thread!

 

Anyway...the core is actually sitting in a rectangular core print. Its formed by a corrosponding piece which is pinned to the back of the pattern. Its removed so the pattern will lay flat during ramming of the bottom half of the mold. Once its been flipped over the piece that forms the core print is attached (aligns with dowels) and the other half of the mold is rammed leaving the imprint for the core. It worked quite well.

 

Best regards,

 

Terry

 

 

 

 

[Barney]

Hi Tharper,

I found your posts very interesting and the finished casting and etched plates are a credit to you.

I wonder if you could you answer some questions regarding sand cores?

Do you use Petrobond for the cores?

What temperature do you bake the cores at and for how long?

Do you make any allowances for aluminium which has a high shrinkage rate as I have read in an old book that the cores need to be softer than for other metals to stop contraction cracking of the aluminium?

Thank you.

 

Best regards. John

[Old Bill]

 

 

Hello Steve,

 

I use Pine for the patterns..........

 

Best regards,

 

Terry

 

Thanks Terry. I think you must get better pine than we do!

 

It is wonderful to see how you do it with removable pieces and so on. I have learned so much from seeing your step by step pictures of the process as well. Thank you very much indeed for sharing them with us.

 

All the best,

 

Steve:-D:

[Tharper]

Hello John,

 

Its just a core sand (as close to 100% silca as possible) There a hundreds of recipies for core binders - Flour & Molasses is one that works well, Linseed oil use to be used a lot. Now sodium silicate is quite popular. This is cured by exposure to CO2. You can even make no-bake cores from green sand.

 

Baking time and temp depends on the size of the core. Bigger cores need to be baked at a lower temprature for a longer period to insure they are cured all the way through.

 

I have not heard of using soft versus hard cores...but the pattern must take into account the shrinkage rate for the metal and alloy being used. What the foundry guy does with gating, risers, shrink bobs etc. also affects this.

 

Thanks Terry. I think you must get better pine than we do!

 

Steve,

I live in the Pine Tree state. The pines here were once emblazoned with the King's broad arrow mark and were favored for masts for the Royal Navy!

 

Best regards,

 

Terry

[Barney]

Hi Terry,

 

Many thanks for the sand core info.

 

Best regards. John

[Great War truck]

We have just had another weekend in Devon, ostensibly to celebrate parents Golden Wedding but really, another excuse to work on the lorry! We decided that it was time the clutch came apart so the first job was to remove the locking pin from the centre nut.

 

 

 

This is a ring of spring steel with one end bent inwards at 90°. This end locates in a hole in the nut and another in the shaft and is an arrangement we have never seen before. Then, Father took the opportunity to remove the lining which unfortunately, is a bit ropy and not worth using again. It was secured with 5/16” Whit worth countersunk screws.

 

 

 

 

[Redherring]

The spring clip seems to be a very early idea. My Leyland uses one to lock the cover of the thrust bearing which sit on top of the king pin. The cover was beautifully machined back in the early 1910's. There are no makers markings on the cover which is a little odd as Leyland stamped pretty much everything with a design number.

[Great War truck]

The lining came off in one piece so Steve will take it somewhere to get a replacement cut the same shape.

 

 

Next, we tried to remove the centre nut, 1 1/4” BSW. In spite of our best efforts with heat and assistance from our neighbour, we could not hang onto it tightly enough to free it. Then Steve had a brainwave and tied it to one of the shed door pillars, wrapping the rope around it like a windlass so that it got a grip. That got it!

 

 

 

 

once the nut was off, the end of the spline could be seen in the middle of the coupling spider. To get the spider off, it required jacking. Over twenty years ago, Steve had the same problem with the Thorny gearbox and to remove that coupling, he made up a plate. Amazingly, he remembered that he had made it and miraculously managed to find it! It even had a set of bolts in it so it was soon pressed into service, once again.

 

 

Of course, the coupling would still not let go and we sheared off the centre bolt. A new bolt was found and with the generous application of heat, it eventually unstuck.

 

[GeePig]

If you are interested in checking cam timing, a good, easy to understand guide is the BG/Piper Tuning Guide, available online.

 

http://www.bgideas.demon.co.uk/tmanual/

 

Chapter 5 covers camshafts.

 

I used to work with the author, Bob Gaylor, when he was a director of Piper FM, one of my most enjoyable jobs.