Allan Brothers Lampless Oil Engine

Model Engineer 24 July 2015 issue 4513

This is a nice looking engine however, I think the side frame drawings are incorrect.

The dimension to cylinder centre line is 64mm but the position of R2 is 50mm + R2 which is 19mm = 69mm which is clearly drawn well below the centre line of 64mm.

Also the 14.5mm and 15mm dimensions from the crank end of the cylinder appear to contradict one another.

I would say that R2 should be 9.5mm and the diameter has been listed by mistake

Looks like the dimension line at the right of the 14.5mm dim should do to where the sloping face meets the ctr line eg the point where the 96mm arrow is pointing to as this seems to be just withing the thickness of the 15mm plate.

I also don't think the cylinder ctr line is 64mm above the base, that looks to be where the flat side meets the arc of the plate the cylinder mounts to. One of the two 64mm dims should be teh cyl centre height.

The 32mm length of the slope under the head also looks wrong if the height is 27mm and assume its about 45deg so should be 38mm or there abouts. (this should be 60 deg according to text and photos!) Not having this line correct throws the 0,0 datum point to anywhere so who knows what the coordinates are. Taling of coordintaes should they not have two values eg X,Y? and where are C1, C2 and C3??

Split line of the bearing cap is not drawn at anything like 30deg

As you say nice looking subject, I had only glanced at it on the digital as I prefer to read the printed version which has not come yet.

Edited By JasonB on 22/07/2015 13:51:40

Yes, I see the 15mmm is the plate but the 64mm dimension is still well above the position of the 69mm dimension. As the 64mm is not the cylinder height, this dimension is missing. Working it out is 27mm + 15mm + 20mm (1/2 of cylinder diameter) makes it 62mm centre height which is even lower than the 64mm height. The correct dimension would be useful to set out the crankshaft centre height with. Bearing caps are probably 60 degrees. The 30 has been rotated around.

Also, what do the co-ordinates C1, C2 and C3 refer to? Are they the x co-ordinates of R1, R2 and R3? They are not shown or stated on the drawing?

The cylinder centreline should be 62mm - 20 + 17 + 40/2. That is also the dimension given for the height of the crankshaft centre.

The co-ordinates do give X and Y - the decimal points should be commas! Yes, C1, C2, C3 are the centres for R1, R2, R3 and C4 is the crankshaft centre.

The 62mm length for the cylinder also seems wrong as it's much longer than the height of the cylinder centreline. Maybe the drawing has been distorted in printing?

John

Got teh paper one to look at now.

Cylinder centre height 27 + 15 + (40/2) = 62

That seems to tie in with the co-ordinate of 158,62 but who can place 0,0? If the angle is 60deg and the height 27 then 32mm is wrong.

64mm dim must also be wrong if cyl ctr is 62mm

42mm length is much longer than the 40mm dia, same as the 62mm lengt looks like it should be 92? And the 6mm slot is about as wide as teh 13mm dim below it?

Edited By JasonB on 22/07/2015 15:51:20

Edited By JasonB on 22/07/2015 15:54:18

It needs drawing out on a cad system to ensure it is correct. I missed the decimal point error. Not worth starting the project until all has been published.

I'll have a go at drawing it later.

Just had a go at drawing it out and it seems impossible. To me, there seem to be some vital dimensions missing. You really need the position of the cylinder bolting face from the datum point. You can work it out from the drawing for the base. I reckon it should be 60mm. That makes the length of the slope at the datum end to be 32.45mm.

Can't understand why it's been dimensioned like it has. Don't like to be critical but It's a dreadful drawing.

John

Edited By John Baguley on 22/07/2015 16:23:51

Yes the 60mm would tie in with the 47 +13 from the base but where the 13mm starts from is debateable as the datum if its on a 30deg line is not 7mm in from the end.

The datum looks like it is on a 45degree aproximately angle which would make it about 12mm from the end.

I give up! I'll go and do some gardening instead

John

Looks and text don't agree though.

Text says its on a 30deg line but drawing looks nothing like that, length is almost right for a 30deg line. Base is 9mm thick at the edges so at 45deg would be 9mm in but at 30deg should be 5.2mm in. Fig 1 would have it somewhere between the two at 7mm.

I have asked Di to send me whatever the original sketches were and will see if I can draw it from them.

Yes, I omitted the rebate.

Original drawings are basically whats in the mag

C1 and C2 co-ordinates seem to be wrong but playing about with things and looking at photo 4 I can get this as a basic shape which seems about right.

Bit more detail on the side plates

And add the baseplate

Edited By JasonB on 23/07/2015 07:39:24

I've added the bearing caps

I do have details of some of the other parts shown on the GA drawing in fig2 but will not add those until published as I would like to read the text that goes with them and don't feel it would be right to get ahead of the mag.

If anyone actually wants to have a go at making this model let me know and I'll produce dimensioned 2D drawings from the above 3D ones.

Well a couple of people have expressed an interest in teh drawings so here they are, you should be able to get them larger by clicking or viewing in my album "Allan Lampless Engine"

Edited By JasonB on 26/07/2015 19:08:25

Is anyone building this or considering building it