1914 Dennis Lorry

Goodness, what a job! There is great satisfaction in salvaging original parts but I do think I might have given in on that one!

Well done!

Steve :-)

In my 1927 Citroen workshop manual they repair broken aluminium engine parts by making steel moulds and casting new metal in. I will find it for you and scan it. It's in French but maybe it's usefull for you.

As promised

Thanks, I did try this once but missed out preheating the existing casting and the special powder

It is 20 years since I gave up French at school but I think it says this

1. Clean, and file back

2. Make mould

3. Heat existing casting with torch

4. Heat aluminium wire and use it to apply special powder to casting

5. Melt the edges and sufficient filler metal to fill the mould

6. Cool slowly

7. Free the mould from the legs

It certainly looks like it would be a useful technique; I wonder what the special powder was.

I had to work in Germany for most of this week so I have not made any progress this project.

I wonder what the special powder was.

It would have to be some sort of flux to cover the surface and keep the aluminium from oxidising

I wonder how close it was to "modern" flux for aluminium welding; this appears to be a combination of metal chlorides and flourides.

Yes the translation is ok, what the powder was i don't know either.

I am still unsure about casting new bits onto my fragile old castings so I have continued with my glue and screw repairs.

One of the bolt holes on the lower half of the gearbox was broken off. I filed it back to a flat surface and milled a new lump of aluminium to fill in the gap; this piece only really needs to stop the bolt sliding out of the hole.

It was then glued in place.

Holes were drilled and tapped through both parts (but not far enough to break through)

Threadlocking four stainless set screws.

Shaping with a saw and file.

Final shaping completed

I heard the older aluminium castings were of a purer quality that made it easier to repair them than the modern alloys? You never know what they mixed in there.

A trial fitting of the transmission brake components showed I did not have a full set of compatible parts. The shoes do not line up with the shaft axis so that is something that needs to be resolved.

I continued to repair the gearbox casing and finally gave it a coat of paint.

Still a bit of work to do on the contents but the box looks reasonably tidy.

Many hours have been spent on the transmission brake casting this week. The first job was to mount the large four jaw chuck to the lathe and centre the casting with the aid of a dial test indicator. This is often quite a challenge with castings.

My pattern had left a reasonable amount of machining allowance so I was fairly confident all the important surfaces would turn out OK.

I started with the boring and facing.

Then machined the outside diameter.

I had to skim the bore out slightly around the mounting lugs as I had made the pattern slightly too small in this area. I fixed a stop to the bed to make sure I did not end up machining the chuck jaws.

And then chamfered the edges.

The next job will be to turn it around and machine the other side.

Ben, the casting seems perfect without any flaws at all. Did I miss the pattern being made, or can you point me to the appropriate page?

Barry.

Ben, the casting seems perfect without any flaws at all. Did I miss the pattern being made, or can you point me to the appropriate page?

 

Barry.

My glamorous assistant has found it on page 36!

Other than one poor batch of castings I have been very lucky!

I have attempted to use up all the left over Dennis parts that might have been used as "in service" replacements on this project. This original gearbox and transmission brake arrangement would have been this one with a 9.75" transmission brake.

The gearbox I have is the later one (appears to have been introduced in 1920) and allows for a power take off and a larger transmission brake with pivots mounted from the gearbox rather than the chassis rails. I have kept to the original 9.75" diameter (this also matches the brake shoes I have).

I heard the older aluminium castings were of a purer quality that made it easier to repair them than the modern alloys? You never know what they mixed in there.

Early aluminium/alloy is full of impurities

Can make it difficult to weld with the argon set...

I reverted to the three jaw chuck and machined the other side of the transmission brake drum.

Followed by marking through the holes in the hub and drilling the mounting holes.

A trial assembly with nuts, bolts and Grover washers. I still need to cross drill the holes for split pins.

We marked up where the mounting holes for the gearbox should be drilled and clamped it in place to make sure everything lined up.

Then drilled the pilot holes.

As the selector drop arm also seemed to line up I put it back on the shaper to continue roughing it out.

I have been lining up the Hooke's joint hub in the milling machine. I think there is just enough height, so I should be able to bore it out to size.

I have been to an auction this week and purchased a more appropriate acetylene generator that does not appear to have been used for several decades. It was made in Powell and Hanmer of Birmingham (who also manufactured the side and tail lamps).

It still had quite a lot of Calcium Hydroxide in it.

Ben, I cannot see any trace of the original gearbox mounting holes. Had you already welded them up? The acetylene generator is just the job!

Barry.

Ben, I cannot see any trace of the original gearbox mounting holes. Had you already welded them up?

 

All the way back on page 2, I fitted new rails for the engine and gearbox as the originals had been removed (presumably as part of it being converted to a trailer).

I had looked at lots of acetylene generators but they all seemed too expensive. This auction only had a couple of veteran parts in it and did not have online bidding so I thought it was worth attending the sale.

Nothing too exciting this week; mostly small jobs like cross drilling bolts for split pins and opening up the gearbox mounting holes in the new chassis rails.

A little more roughing out of the gear selector drop arm.

I need to mark it out in the opposite plane and repeat the process.

Back on post 376 I collected the clutch casting. There is quite a bit of machining to do on this so I started with clocking it up to find a good approximation to the middle and skimmed the inside face before boring the centre out to 4" diameter to fit the central spigot.

I want to get the clutch finished before committing to the flywheel casting as it will be big, heavy and also expensive to machine as I don't have the capacity to do it myself.

At over 14" diameter I can't machine the clutch on my straight bed 6.5" centre height Colchester Master. However I am able to use a gap bed Colchester Student so decided that was probably the route forward.

The first job was to set the compound slide accurately to 12 degrees. As it is difficult to get the precision required for this job from the marking I used dial gauges to set it up.

The next stage was to check what taper I was actually machining by using a trial cut on a bar end where I had machined a groove exactly 1" from the end so I could take accurate measurements of the taper per inch. As this was coming out correct I assumed the error over the 3.5" of lining would end up being no more than a few thou and would easily be corrected as the lining wears.

It is probably a bit bigger than the lathe is meant to machine. As the outside was taking shape I checked nothing was going too wrong with an angle finder.

The tool holder was reversed for facing the far side off.

The front face was machined gently as I did not have the security of the centre pushing the casting onto the lathe jaws.

I still need to machine the four holes for the hub securing bolts, the three holes for the springs and remove some of the excess material from the inside faces.

My other job for this week was to machine the universal joint hub. It was kept off the table of the milling machine on two parallels and clamped in a machine vice, using a scrap of aluminium machined to the same length on the other side of the jaws.

A centre finder was used to centre the spindle axis on the centre punch mark.

Before drilling the first hole.

The hole was enlarged with successive drills up to 25mm. These had to be blacksmith drills as my milling machine is relatively small. This did mean I had to peck at the holes once I was past the flutes as the swarf could not escape; but they were not long enough for me to accidentally drill the table.

The boring head was then used to open the hole up to around 0.990".

The hole was then reamed out to 1"

Trial fitting of the drive pin

The procedure was repeated for the second hole but a clamp was also used. This hole partially intersects the first one and I was worried the loads may be higher when breaking through.

And trial fitting the shoulder bolt. This bolt had to be polished slightly as it was a few tenths larger than 1"

I am not entirely sure about the cab dimensions so I will cut the profile out to see how it looks/feels.