Fowler BB1 in 2"

[Jasonb]

The casting box does sound like the way to go, if you were cunning you could make a pattern that you could get the winding drum ring gear and one of the smaller gears out of thus saving room in the box. You could also add some basic holes in the patterns to remove the excess material between the spokes rather than make a detailed pattern with the "+" section spokes.

The iron will also be a lot easier to cut the teeth into.

Think you need to have a read of Conrads diary about patterns & casting the gears.

http://homepage.ntlworld.com/corromant/construction.htm

Looks like I better get that S&P base finished as I see the need to be making more things

[Jo]

    


 

[b.lindsey]

Jo, would seem that a few of the moths are safe then until another day

Bill

[Jo]

  It had to be done: green stuff  I have started turning up the winding drum and driving gear wheel patterns, thankfully even the winding drum gear fitted on the smaller of the two faceplates:



These patterns are just straight blanks I see no point it making elaborate patterns only to have to repeat the exercise when it comes to machining them. So far I seem to be collecting a few:



Sadly the postman still has not delivered the blackboard paint that I have been instructed to paint them with and the swarf

Jo

[steamer]

Run the shop vac while your turning it Jo....it will control it pretty well.

Dave

[Jasonb]

I thought that you might have thinned out the centres a bit even if you don't cut the actual spokes, it will make quite a difference if they charge by the Kg. I'd also think about casting the reinforcing webs into the top of the drum as it will save lots of machining.

Also hard to see from the photos but have you put a draft angle on the edges?

J

[Jo]

The gear wheel spokes are cruciform, so would need to be a two part pattern .  By putting the other gear wheels on as a stack I have something to hold in the chuck but it does not leave many options for saving metal, maybe a shallow undercut on the bottom up to just before the smaller gear. Based on the price for solid bar of the larger size spending lots of time undercutting might save £5 on the casting price but increase the possibilities of casting flaws. The foundry prefers simpler patterns so if it takes them longer setting it up they might charge me the extra £5 for their time any way. I can get all of these in one box (£50), if I do them seperatley I will need three boxes (£150)

This is the top of the winding drum, the flanges are not very big and I am tempted to add them after rather than make myself lots of work. I was thinking of adding a steel ring under the gear ring as the flange 

As you know the dutch guy machined his out of solid, that was where I was going. These patterns are all about getting a solid blank to machine the bits out of, which should be cheaper than buying bar and having to pay the excessive cutting fees.

There is a 5 degree draft angle.

Jo

[Stuart]

Jo

That poor lathe the state of it with all that brown dust on it proper made me cry got though a box of hankies just looking at it

nice work on the project don't forget as Jason has said the draft ( not the one under the door )

Stuart

enjoy your visitors on Wednesday 

[Jo]

Jo
enjoy your visitors on Wednesday 

Thanks Stuart, My nephew is visiting on Thursday. Not sure what to do this year... Sis wants me to let a 9 year old loose on a lathe  I have watched him on my Wii computer game... he doesn't have the motor skills  .

I did however recover my Mecanno Construction (building site) set from my parents  A bit more practise with bending bits of metal, screwing things together, getting nuts and bolts the right tension would not go a miss.

Jo

[Jasonb]

I thought the Dutch guys cast the top and placed it onto a steel plate. Even if you did not cast the ribs you could just trepan a recess. The smaller wheel from te centre could just be connected by the 4 "tabs" that lay over the central cross.

[Jo]

  I am not doing that the original has a smooth round inner rim (and that is reflected in the lower casting). I know the original Fowler Drawings show something different.

And if you look at the flanges there is a very important gap between each where it joins the centre.. between each is a drainage hole 

Jo

[Johnmcc69]

what a nice project! have not seen a model of this before...
 I remember seeing a video of one of these monsters dragging a small Caterpillar dozer across a field.
Very impressive!

 John

[Jasonb]

I am not doing that the original has a smooth round inner rim. What ever the drawings say.

And if you look at the flanges there is a very important gap between each where it joins the centre.. between each is a drainage hole 

Jo

Yes the bump around the holes should only be on the lower casting, the top ring should be round as you say. Jan's 1 1/2" one has it correct and its shown on that drawing that I sent you though they have missed a bit of hatching.

But the drain holes don't all work when the drum is laid at an angle

[ths]

You've been very brave with the wood Jo. Next you'll find yourself considering working with something with grain! All the best for the season.

Cheers, Hugh.

[Jo]

Since my last post the patterns have had their edges smoothed and the corners smoothed with some car body filler so today they were independently inspected and I am pleased to say passed muster , so they now have been given a coat of blackboard paint 



I am going to see how they go (and cost) at the foundry and then look at making a more complicated set of patterns for the cylinder. And he also inspected those other three little patterns  in the foreground which are not for the BB1 


And how did that happen, I have let a set of my engine castings out of the house

Jo