Errors on drawings

[jools]

Studying The Don Young Black 5 drawings today, in particular the Bogie Bolster assembly.
Drawing 4 of the series shows the above assembly. The end plates of which are drilled and tapped to suit the main frames.
There are two parallel rows of 5 holes; one row of holes (the lower) are drawn on 0.5" centres and the upper row of holes are on 0.375" centres. Looking at the bolster assembly, the flange looks to fit under and butt up to the main frames. The sectioned bogie assembly drawing seems to corroborate this. So to my understanding the flat face of the bolster is facing trackside mating to the pivot that is fixed to the bogie frames.
Now looking at drawing 5 that show the main frames, two discrepancies are found , to my inexperienced eye bearing in mind I'm not at the assembly stage yet.

The first discrepancy is that the two rows of holes are inverted in relation to the bolster side plates.The frames show the 0.5" centre holes on the top and the 0.375" centre holes underneath.

The second discrepancy is that the upper row of holes is drawn on angle similar to that of the cylinder mounting plate which is incorrect.

Just wondering if anyone building one of these has come across this before or can point out that I may be missing something......

cheers Jools

IMG_1060 by Julian Hardy, on Flickr

IMG_1061 by Julian Hardy, on Flickr

[Rex Hanman]

Jools,

Unless I'm reading it wrongly, your red rectangle on the second drawing is about a 1/4" too high. Lower it and the holes match.

[fostergp6nhp]

As Rex says, but the stretcher does not use all the bolts in the bottom row on the frames.

[jools]

Thanks Guys, much appreciate the assistance.
it was a long day yesterday..........I thought it would be something simple.
Those additional holes probably threw me !

Jools

[jools]

Looking again at this, I suppose what threw me is that I was looking for the 5 holes in the middle of the lower row to be Countersunk. It looks like the lower bolster bolts through from both flange plate and main frame so on assembly its only possible to fit the top fixings until the cylinders are ready to fit.

IMG_1063 by Julian Hardy, on Flickr

Green boxed holes are cylinder to flange fixing, green boxed are flange to frames.

[dscott]

The Class 2 does the same and askes for Brass plates, The previous builder has them in steel but as I am going to duct the exhaust up two pipes each side in copper there will not be an issue...
In fact, the 5 should have two pipes for exhaust as it speeds up the restrictions of going round sharp bends!!

[ettingtonliam]

I'm not building this, so probably have no right to comment, but purely as a drawing check exercise that row of 5 holes at 0-375 crs is shown as 25/32 up from the flange of the bolster, which is presumably meant to fit tightly to the underside of the frame plates. The same row of 5 holes on the frame drawing is shown as 3/4" up from the bottom of the frame plate, a discrepancy of 1/32". The row of 5 holes at 0.500 crs on the frame drawing I don't understand at all. Its at an incline to match the cylinders, but isn't shown on the cylinder drawing, and is far too high to be for the bogie bolster. It would only make sense if it was below the other row of 5 holes, and horizontal, to suit the bolster, BUT its then foul of the lower row of No34 size holes shown as marked through from the cylinder block flange. Looking very carefully again at the bolster drawing, the lower row of holes seems to be slightly inclined, so probably the intention is for bolts at this location, through the cylinder flange, the frame plate and the bolster flange.
This would mean that the upper row of 5 holes shown on the frame drawing as No34, csk is superfluous.

[Deleted]

Don does his drawings a little strange at times which is surprising for a trained draftsman ..he's caught me out a couple if times...IIRC...on Doncaster he has drawn thr tender dragbox upsidedown....this has caught other builders out too so not just me...also his main frames are drawn from the inside?..I had machined a couple of csk holes before realising....luckily I spotted it before getting carried away...
My reason for mentioning this is to say look twice and then again....

Pete

[Rex Hanman]

Nov 17, 2017 10:24:45 GMT ettingtonliam said:

I'm not building this, so probably have no right to comment, but purely as a drawing check exercise that row of 5 holes at 0-375 crs is shown as 25/32 up from the flange of the bolster, which is presumably meant to fit tightly to the underside of the frame plates.

How did you get the 25/32 dimension? Did you subtracted the 7/32 from the 1 inch? I think the 7/32 refers to the chamfer, I don't think it is quite on the centre line of the holes. I am due a visit to specsavers though.

[ettingtonliam]

Nov 17, 2017 15:47:16 GMT Rex Hanman said:

Nov 17, 2017 10:24:45 GMT ettingtonliam said:

I'm not building this, so probably have no right to comment, but purely as a drawing check exercise that row of 5 holes at 0-375 crs is shown as 25/32 up from the flange of the bolster, which is presumably meant to fit tightly to the underside of the frame plates.

How did you get the 25/32 dimension? Did you subtracted the 7/32 from the 1 inch? I think the 7/32 refers to the chamfer, I don't think it is quite on the centre line of the holes. I am due a visit to specsavers though.

Yes, I think you are right about the 7/32" dimension referring to the chamfer. Holes in the bogie bolster seem to be positioned by spotting through from the frame plates. I'm due a visit to Specsavers as well, had the test, now need new (stronger) glasses.
I still think that upper row of 5 csk No.34 holes shown on the frame plate drawing are superfluous, though.

[jools]

I had to look and cross reference several times as its a tad confusing, but all will probably become clear once I have some bits of metal in hand rather than trying to visualise between several sheets on and off the screen.

Pete - is that common knowledge about the main frames being drawn viewed from the inside ? I have yet to refer to his ME notes, which I have a copy of.

Jools

[Deleted]

I don't know Jools...it may just be on Doncaster...I had assumed that they would be from the outside...only when reaching the countersinking stage did I question this which was confirmed when rechecking and finding the Don had made reference to this...I can't recall now if this was in his words or on his drawing...I think it's the drawing...if I can remember I'll try to take a look during the ext few days...alas my comouter has finally died so can't check my digital copy which is much easier for me...I'll try to read the originals...

Regards

Pete

[ettingtonliam]

If the way the countersinks for the bogie bolster fixings are drawn is any indication, then the Black Five frame drawings are shown from the outside.
Tread carefully, would be my advice, think it through before any countersinking.

[44767]

The row of holes you're talking about does need countersunk holes. They are for the heads of screws which fasten the smokebox saddle. These heads are behind the cylinder flange and are permanent while the cylinders are removable. They get transferred through the frames to the smokebox once it's setup in place.

[Geoff (Carlisle)]

Hi all, again following J.Ps drawings I decided to drill the two 6 B.A. holes for the imitation exhaust injector in the side of the ash pan only to find that it fouls the handle for dropping the ashes , so I had to drill two more which may put the injector exhaust steam pipe laying it over more of the wheel. So beware all Britannia builders.

Geoff (Carlisle).

[madmonkey]

Hi everyone,

I've been looking through the drawings of the 2" Fowler Showman's by Plastow and trying to draw some of them into CAD. I lack a lot of experience model engineering so the CAD helps me iron out problems.

Tried searching for errors in the drawings but the links I found don't seem to work.

I've been drawing the front wheels and axles and noticed there are two dimensions for the bronze bushing diameters. The casting is spec'd at 3/4" but the bushings at 13/16" diameter. Anybody built the model and know what diameter they should be? I guess an interference fit is needed but 13/16 is too big.

Thanks

[ettingtonliam]

Are these the original drawings by Henry Plastow, or the redrawn ones by (I think) Stuart Models after Henry sold out?
If they are the original ones you are in for some fun, because, nice man that he was, Henry P was no draughtsman!
I built a 3" Simplicity roller to his drawings, but it was available in 3" scale and 4 1/2" scale, and he'd made one set of drawings do the work of two, simply by by putting 2 sets of dimensions on one drawing. What a nightmare!

Like most model drawings, you won't find close dimensions anywhere. If a bush is supposed to be a press fit into a housing, you won't find, for example, the housing bore dimensioned at, say 0.750" and the bush OD at 0.752". Oh no, both will be dimensioned at 3/4", and its up to you to size things to fit. Its just the way the model engineering world is. Tolerences? Not a chance!

Good luck

Richard Wilson

[madmonkey]

They are from Stuart Models but I don't know what edition/revision, I'll look when I'm home.

The CAD should pick up most of the errors so hopefully that'll help. I didn't think I'd get tolerances but I thought I might get measurements the same when they're next to each other lol. I'm going to end up with a lot of questions I feel! At least I get to practice my CAD skills.

Thanks for the reply.

[Midland]

Trivial but worth recording, the Princess of wales grate dimensions are very wrong, just scale from the drawings to find out!
D

[madmonkey]

I think I have worked the drawing out. The measurement refers to the ring securing the wheel to the axle it seems, although the rest of the measurements and drawings for it are on the other side... This is going to be fun 😁