Asciidv

Timing diagram from a  1920’s 4 cylinder SV engine of 3 litre capacity. Still not radically different.

When you compare the Thorny with the Dennis, the valve timing looks very similar. The duration of the Thorny exhaust period is shorter but the difference is located equally with respect to the Dennis exhaust timing. Is the problem really valve timing after all?

This is the timing diagram for the 4 litre Dennis sidevalve engine of the 1930’s.

6 hours ago, Old Bill said:

I have some film files to post once I have worked out how to do them

I have just realised why the delay. The films must have been Super 8 and have been sent away to be processed......

Steve, does this mean you are going AWOL from Dennis Eagle or was it always your plan to have extra time off? As one of the previous posts said, you have the whole world waiting with baited breath to hear it run for the first time. Tim should have set a live streaming on Facebook so we could have watched it as it happened.

The offset crank is a beautiful piece of work, with lovely fillets into the bosses. Almost too good to go onto the Thorny!

Andy, if you remember from the Dennis thread Tony bought a Black and Decker 'Power File' on my recommendation to clean up the steering wheel casting. He managed to blow it up in less than a day!

20 hours ago, Old Bill said:

My welding has improved slightly but I did put down 30, 3mm rods in the course of this exercise

Steve, a definite improvement! However, isn't it tedious knocking all the slag off ready for another pass? I know so many jobs would be easier with different equipment and you just have to prioritise what you would buy next, but I think top of your list should be a 250A MIG welder. 

Marcel,

I like the way how you achieved parallel sided splines accurately. I assume that you just milled away the smaller 'leftover' spline. Although I gain satisfaction from making parts with the 3D printer and the Wire EDM machine, I know it would not be anything like the pleasure that you get from making parts like this on machines from the same period as your vehicle. Andy posted a link to a video of a man setting up to cut some splines. There were 6 or 7 edited videos showing the whole process. I think I was set up and cutting splines in the time it took for half the first video to play, so there are some compensations.

Gordon, you do have to compensate  by machine adjustment for the type of material you are eroding. However I don’t think the Thorny would really notice as we are only talking about a thou or two. Wire erosion is incredibly accurate. The party piece trick is to make two parts size for size and slot them together. Here is Steve’s spline gauge with the matching inner part.  Only if you look closely by the arrow can you tell that there are two separate splined components.

Spline Gauge Mark II !

The 1/4" slots for the splines are now 5 thou. wider and there is a 15 thou radius on the inner corners of the spline.The wire diameter is 0.25mm so there is a natural 7 thou radius on the outer, inner corners of the actual wire cut part, which isn't shown on the drawing.

Lovely to have the original registration for it. CC1720 has a nice 'ring' to it. It puts it apart and makes it stand out from all the 'SV' registrations!

I am just trying to work out what new toy you have on your sack barrow!

If the Thornycroft factory was like the Dennis factory, everything was brush painted exclusively by women.

10 hours ago, fesm_ndt said:

Those small little engineer books used to state mandrel radius and also offsets depending on thickness.  I have one of those books at home but I am in the middle of a dessert at the moment.

Fesm-ndt, if you have chance when you get back from eating your pudding, I would love to see a scan of the table of offsets and mandrel radii. I made a rudimentary mandrel bender for one size of pipe and just guessed and experimented with the settings until it worked, never thinking that there were tables of such information.

Thanks,

Barry.

If you pop over to Ben Hawkins Dennis lorry thread you will see that Ben reached the same point as Steve but a week earlier. Andy suggested packing the tube with monkeys which I thought was a very clever and amusing suggestion!   ( I am sure you can work it out....), Seriously though, mandrel bending  is the only way to achieve tight bends ( 3 x tube diameter) in light wall tube. I made a mandrel bender for one particular application and it was well worth the time spent as there was multiple tight radius bends.

Andy,

Did you mean one of these or one of those?

As braze has very little capillary action but more or less just sticks on top of the surface of the metal, is there a chance by cleaning it all off to make it look nice you have lost all your strength and the flange might crack off in service?  As you know the Dennis flanges always have a tube extension to allow them to be rivetted to the pipe.

However, I have to admire your determination as filing braze is a long hard unrewarding job!

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

Best wishes for the New Year,

Barry.

Steve, I see that there is a rear visibility panel in the rear wall of the canvas. I assume this is as the original. What transparent material did they use originally or was it just left open?

Dan, returning to your need for new con-rods and the general consensus that machining them from solid would be the best approach, can I just add something about having them profiled first to keep machining to the minimum. 

I would opt for water jet profiling rather than laser, as laser profiling can lead to embrittlement of the edges of the plate leading to cracking. Of course it all depends how much you are going to machine off after profiling as to whether it will become a problem.

In fact why not water jet profile to size apart from the bores and then there is virtually nothing to do?

Barry.

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...

Andy, yes it has to be pure Argon.

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.

It all depends on how you configure the ‘slicer’. This is the programme which takes your CAD model of the part and then slices it into thin layers for printing. I typically print with a layer thickness of 0.15mm which is a compromise between the smoothness of the curved surfaces against printing time.  Rather than the print being solid throughout ( which on large prints would take for ever ) you can set the print density and when this is down to 10% the core of the print  has very little material present, hence the screw pulls out. However you can set the thickness of the solid outer ‘skin’ and if set at say 5mm the problem that Steve highlighted would not have occurred.

Andy’s idea of gluing in a wooden dowel is certainly the simplest!

Barry.