B.Hick & Son oscillating engine

[Sanjay F]

I was halfway through making the outer trunnion when I noticed it didn't line up with the inner ........... hmmm. So this where thinking I'm cleverer than the designer didn't pay off.

The drawing shows the bottom of the standard with a slot rather than 2 holes for mounting the inner trunnion, I ignored this completely to my cost. The slot allows for the inner trunnion to be moved laterally to so it can be aligned with the outer

This has now been corrected and I can continue with the machining of the outer trunnion and eventually align my trunnions!.........live and learn 

[Sanjay F]

Next operation was to chop off the bearing pedestal cap in preparation for milling to receive the yet to be made bearing brasses; I'm still not quite sure how I get the centres to of the brasses to the same heights - hoping its as just a case of fitting them and then marking off with a height gauge.....

[Jasonb]

If you have the head room it might be possible to set the assembly up vertically and drill/ream the first bearing. Remove that for access and then do the smaller one.

A similar sort of setup doing the bearing holes after fabrication



I'd most likely just do it by measurement. For the main one it is base height plus bearing height. For the smaller base + A frame = bearing

[Sanjay F]

I did wonder about the vertical drilling/reaming but as you stated not sure if I can set it up. I think I'll need to get both brasses made and positioned before final decision, but I'm leaning towards measurement at the moment 

[Sanjay F]

The larger trunnion bearing is now complete and I think I may make the crankshaft bearings next. All the bearings will then be done and I can make all the brasses at the same time ............

[Sanjay F]

Question

Right back on to the Hicks and I have come to the same conclusion as Jo did regarding the crankshaft bearings and pedestal, this is her quote

"The crankshaft bearing pedestals in the original drawing show a very difficult to machine octagonal profile into which the bearings fit - this just strikes me as inventing unnecessary work on both the bearings and on the pedestals and the bearings are going no where as they need a flat at the bottom to clear bearing pedestal so I have bored them 8mm and adjusted the bearing to suit"

So looking at the drawings (see below), I'll make a standard 'U' shaped pedestal which has a 5/16" cutout and similarly on the bearing cap. I'll then make a square bearing brass (see last pic, but ignore dimensions) which is 5/16" square and a 0.031" lip all the way round and then drill and ream a 1/4" hole through the middle .............does that work?

[Jasonb]

Should work ok

[Sanjay F]

Thanks Jason, good to get a second opinion before getting starting on the machining 

[Sanjay F]

This is a bit strange, the standard shows a gap of 1" for the crankshaft pedestal yet the crankshaft pedestal and its cap show a width of 7/8". Must be a error unless I'm reading something incorrrectly

[PaulR]

Is the 1" the width of the undercut part?

[Sanjay F]

Is the 1" the width of the undercut part?

That made me go and have a quick measure up, but sadly no 1" is lot wider than the undercut; it's no biggy I'll make the pedestals wider but glad I'm glad I caught it before making 2 of them 7/8" wide and them not fitting! 

[Sanjay F]

Michael S has just sent me this image (thanks Michael), so clearly someone else came across this small discrepancy too ........... I like the look of their solution 

[Jasonb]

On full size you sometimes see the gap with fitted wedges which allowed some sideways adjustment, the undercut would seem to back that up.

[Sanjay F]

Aha! That would make sense and make the alignment of the bearings easier. So the bottom of wedges must have the opposite of an undercut, or a 'sticky out' bit (technical term  )?

[Sanjay F]

Made a start on the crankshaft pedestals just the fixing holes to go. I'm not convinced that the pedestals can be positioned centrally lengthways on the standards due the casting on the underside. I think they will have to be brought closer in to each other to ensure their bolt heads/nuts underneath have enough clearance