Perrier / Spink / Blackgate drawing lineage, errors, CAD

[ShmbryParticipant @shmbry]

[ShmbryParticipant @shmbry]

I appreciate this is an old topic however, I am in the process of creating the 5" gauge Britannia in CAD before cutting material. I have an old set of drawings, copyright Spink Newbold and Chesterfield redrawn C.J. Gilbert 6.84. Are these the current drawings and the same as the one's available from Blackgates ?

I have come across several discrepancies the latest of which is a 1/32 difference between the planes of the crosshead (15/32) and the axes of the piston / valve (7/16)

If you have come across this please can you tell me how you rectified it, or has this been corrected on later drawings ?

 

[Les RileyParticipant @lesriley75593]

Norman Spink of Newbold, Chesterfield formerly sold castings and some plans. You will see his adverts in ME from the 60's to the 80's. When he stopped work / died, his business was sold to Blackgates.

As an aside, he was our metalwork teacher at Chesterfield School.

Sorry I can't help with the errors though!

[BazParticipant @baz89810]

Doubt very much if any drawing errors will have been rectified, with model engineering plans, and I call them plans because they are most certainly not engineering drawings, it is down to the purchaser to find the errors, usually the hard way by making the bits and then finding they don’t fit. You are fortunate in the respect that you have only wasted time not metal and time, if it is any consolation all model engineering plans have errors, some minor, some major, none to my knowledge have ever been corrected. I consider it to be a shameful state of affairs.

[Nick HughesParticipant @nickhughes97026]

Going through the same process with the GWR Castle Class by Peter Rich.

Just correct as you see fit, modifying the easiest part to alter further down the line, in case this change causes another problem.

Also triple check everything around any issue you find, before modifying parts, as there could be an accumulation of small errors in other area, causing the problem (in your screen shot, there is also interference between the Crosshead slot and Connecting Rod side face).

For the 1/32" interference:-

Is there an offset in the Combination lever and if so, have you modelled it in the correct direction, or possibly mixed up the LH and RH parts in your assembly?

Nick.

Edited By Nick Hughes on 15/01/2023 14:08:01

[ZanParticipant @zan]

looks to me as I’ve the clearance and interference here would be solved by increasing the cyl block by your 1/32 error. But……….

edit…….nope wont work on looking again  move valve out is a better option……..

 

Edited By Zan on 15/01/2023 14:22:54

[Author]

Posts