1914 Dennis Lorry

[BenHawkins]

On ‎10‎/‎12‎/‎2017 at 8:41 PM, andypugh said:

I wonder if aluminium MIG wire would have worked for filling the pits? 

(The risk is a bit higher than either of the techniques you tried)

I do think MIG could work with the right equipment and if the aluminium could be cleaned sufficiently. It might also help to have a brass heat sink on the under side to avoid the risk of burning through where the material if thin.

I have a few sample plates of cast aluminium (much cleaner than my radiator castings) and gave it a bit of a go.

The main problem was actually wire feed; the 0.8mm wire has very poor column strength and would birds-nest in the drive whenever I tried to weld.

 

I am sure there are a number of things that could be done to improve this; including but not limited to:

PTFE wire liner

Increasing wire diameter to 1mm or 1.2mm

Modifying the front wire guide to reduce the unsupported length.

 

As for covering up the threaded repairs I was thinking about painting the whole radiator with alloy wheel paint. It seemed to look OK on the gearbox.

 

 

 

[BenHawkins]

With the final board for the back of the cab in place I drew on the curve of the roof.

Then cut it out with a jigsaw.

The laser cut steel template for the roof was used again with a router to tidy up the line.

 

Then finally put the board back in place and cut the radius on the interface between the two boards.

[BenHawkins]

I decided to turn my attention to the sides of the cab. My mahogany boards do not have straight edges so my first task was to find a straight piece of timber and clamp it to one side.

Then use the router to follow the straight line; moving the clamps out the way as I moved down the length of the board.

Using the 3-4-5 rule I was able to draw a line at 90 degrees to the router side.

I cut close to the line with a saw then clamped a piece of timber on and straightened it up with the router.

[BenHawkins]

I clamped the board in place so I could mark the lines for cutting.

After trimming the board with a saw I roughly cut the window opening with a jigsaw.

Then screwed the frame on and used it as a guide to finish the opening with a router.

[Asciidv]

As Ben has shown in the above picture, MIG welders don't particularly like pushing the thin Aluminium MIG wire up to the torch head. You can therefore buy spool guns which feed the aluminium MIG wire  from a spool on the torch head. This seems to be the preferred option  for Al MIG welding in a production environment.

 

[andypugh]

1 hour ago, BenHawkins said:

The main problem was actually wire feed; the 0.8mm wire has very poor column strength and would birds-nest in the drive whenever I tried to weld.

Yes, you need a spool-gun or a push-pull feeder. It might be hard to justify the expense. 

Looking at the welds, what gas were you using? That soot suggests to me that you were using CO2 or Argoshield? I am pretty sure it needs to be pure Argon. 

 

[Asciidv]

Andy, yes it has to be pure Argon.

[smiffy]

I would  TIG weld thin aluminium  as it is much more controllable than mig , I use gas diffuser  nozzles and pre flow the gas to get a clean start and pure argon gas, .also a foot control pedal to control the amps is essential ..With some practice its possible to weld soft drink cans and aluminium  kitchen foil

If using  a mig without a spool gun it is worth fitting a new liner as any wear or dirt in the liner will cause extra friction and balling at the feed rollers  and  use 1 mm wire

[andypugh]

54 minutes ago, smiffy said:

I would  TIG weld thin aluminium  as it is much more controllable than mig ,

I don't think anyone has ever had much luck TIG welding 19-teens Dennis castings. Which is why I was thinking that MIG might work better. 

[Asciidv]

Ben, took a piece of early Dennis allloy to the TIG welding shop and said if they could weld it he would buy the welder. They failed...

[BenHawkins]

Thanks for the comments on MIG welding aluminium; I was using pure argon but did not purge the system through so the first couple of arcs were very sooty.

I had just been wondering if I could get away without the spool gun. My MIG power source is pretty basic and does not have a power supply for the spool gun. I could almost certainly rig up an external circuit to drive it all though.

Having given up on welding these castings I had a local impregnation company use their sealants on them and also ordered some Devcon aluminium putty so I can fill a few of the craters.

 

 

 

[BenHawkins]

We went away for much of Christmas but I did manage to clamp the one cab side in position before leaving and router the front edge to follow the line of the ash frame.

I then repeated the procedure to make the other side.

And by the time we were back from the Christmas break the paint was dry on the final arched panel for the back of the cab so it could be fitted.

 

 

[BenHawkins]

The large diameter of the flywheel means it is too big to fit in my press. I am starting to see a common theme here so if I can find the space perhaps I should invest in a bigger (both capacity and tonnage) press. Anyway, the solution for fitting the centre bearing was to machine some scrap metal so I could use M16 threaded rod, nuts and spanners to force the bearing into the bore.

 

That all went to plan and felt like I had sufficient interference between the two parts.

 

But unfortunately I seem to have messed up a bit on the clearance between the taper in the casting and the ball thrust race as it locks up on the cast iron before the threaded collar is fully engaged. When I am feeling strong (and probably with the help of the glamorous assistant) I will need to lift the flywheel onto the rotary table and mill away some of the material.

[BenHawkins]

With the cab sides clamped in place is does start to feel quite complete but there is still a lot of woodwork and painting to do.

 

I have also been finishing off a few of the smaller jobs such as bolting things up and fitting the second steering box bracket. 

[Tamber]

7 hours ago, BenHawkins said:

I had just been wondering if I could get away without the spool gun. My MIG power source is pretty basic and does not have a power supply for the spool gun. I could almost certainly rig up an external circuit to drive it all though.

It is possible to MIG aluminium without a spool gun or push-pull (We do so daily at work.), but using either a spool-gun or push-pull makes life easier if it's available. Ideally, though, aluminium is welded using AC; it will work with your standard DC welder as used for steel, but the welds will be sooty, and generally not as neat/clean as ones done under AC.

As for changes to run aluminium wire: Change the liner out to a smooth teflon one, as opposed to the wound one used for steel (It also helps to try feed the liner in so it's as close to the rollers as possible, to minimise the unsupported length of wire so the soft aluminium wire doesn't kink and bird-nest. It probably still will, at the slightest provocation, though.); run a little less pressure on the rollers, to avoid squashing the wire; and keep the torch lead as straight as possible. Oh, and keep the swear jar handy, because it probably will scrunch the wire up for seemingly no reason.

[Cel]

Hanging the welder vertically from the ceiling also helps, easier though if you have a separate wire feeder

[BenHawkins]

The glamorous assistant helped me to lift the flywheel onto the rotary table I had fitted to the milling machine. A dial gauge was used to make sure it was coaxial with the rotary table before bolting it down. I tilted the milling head to 10 degrees and fitted an end mill to allow me to reduce the diameter of the central boss by around 0.1".

I then returned the milling head to a vertical position so I could machine a radius will a ball nose cutter.

 

Which means the clutch hub parts now have clearance and can spin as they should.

[BenHawkins]

Although the ball bearing tracks for the thrust race are in good condition the balls themselves were very rusty. I decided to remove them from the bronze cage.

 

They are 1/2" so I used a 1/2" ball nose cutter to make a punch with the appropriate radius.

 

And filed a slot in a piece of tube to support the cage.

 

[BenHawkins]

The balls were then easily punched out of the cage.

 

The balls were then replaced with new ones following the same procedure.

[Asciidv]

Ben, Why don't they fall out again, or am I jumping the gun?

Best wishes for the New Year,

Barry.

[BenHawkins]

Some time ago I removed the broken flange from the end of the exhaust manifold and had a new blank cast. I machined diameters and then cut the screw thread. The Aster Engineering catalogue usefully informed me that the thread needed to be 2-1/8" x 11tpi

 

I had to machine the thread deeper than expected before it would fit into the manifold. Actually it seems closer to 1-3/8" BSP

 

I then started machining the mating flange.

 

[BenHawkins]

6 minutes ago, Asciidv said:

Ben, Why don't they fall out again, or am I jumping the gun?

Best wishes for the New Year,

Barry.

When the balls were originally fitted the brass ring was then indented at each opening to prevent the balls from falling out. I thought I might have to do the same after fitting the new balls but actually the cages appeared to elastically deform and just close up after then balls were fitted so the ball stay in place on their own.

Best wishes for the new year to all the projects!

 

[BenHawkins]

The holes were then located using a stub drill in the milling machine before drilling through in the pillar drill.

 

The flanges were then tried in position. The exhaust pipe route looks like it will be a bit of a challenge but that fun will have to wait until another day.

[steelman]

Quote

Here at our work shop (we are steel fabricators), we have been asked by customers to fill pits and holes on old aluminum castings many times.  I have tried mig and tig techniques unsuccessfully.  Even my own projects, after cleaning chemically and blasting the parts, would not weld properly.  Several welding supply vendors have suggested that the alloys used in yesteryear are not compatible with the alloys we use today, therfore the welding doesn't work very well. I have stopped trying, and use epoxy such as lab metal or Devcon as one of you suggested.  One other product I have tried is an aluminum solder, which is often sold at flea markets and car shows.  This material is a low temp. melting alloy, able to be melted with a propane torch.  I have seen it used to repair boat propellors, solder two aluminum drink cans together, fill cracks and pits and a dozen other uses.  My local welding supply can also sell it if needed. 

I continue to be amazed at the quality of the work you folks perform.  Thank you for sharing.  Carey Leitch, aka steelman.

 

[BenHawkins]

Thanks for the comments on the aluminium castings; I decided to proceed with the aluminium putty.

I painted the outside of the header tank with alloy wheel paint then brush painted the nameplate.

We gave the core another clean and painted it with an aerosol can of radiator black.

The side castings were painted to match the header tank and refitted.