Axle Box Timken Covers Part 3.

Looking at the Axle Boxes on Oliver Cromwells tender there is a fifth stud which is not on the same PCD as the rest. This was the next job.

Rather than use the centering indicator I opted for a simpler method. A machined centre! Distance from centre of cover (Y axis) was 4.7mm, PCD for comparison was just over 5mm so not a huge difference.  The X axis was set up by eye to be centred between the two lower holes. 


Hole was started with a slocombe drill

The opened out to 1.5mm to give a slack fit on a 12BA stud.


These will sit proud of the surface unlike the four counterbored bolts.


Now moved over to the Pantograph Engraver, I'd calculated a reduction in size of 6:1 but this left the Letter height too large. I've set it to 7:1 at the moment but might have a look at using a wider font to see if it matches the original better.


Will try some test engraving I think before committing to the real axleboxes - not like me at all!

The test piece looked good so it was a full steam ahead.


Because the spacing between lines was to much I had to engrave Timkne first on all of the boxes and then reset for the B.R.


Each box required a tweak to the centring.


B.R. added.


I have the lighting at an oblique angle to make it easier to follow the text.


Finished the set.


They will need deburring with some emery paper


This is the font set I used. SC stands for Small Capitals. It was a good match to the original but the K wasn't completely correct but the difference is hard to see.



Comments

Post a Comment

Popular posts from this blog

Introduction

Image
We'd had a 2.5" gauge rally at my local model engineering club in September and one of the guys was running a 3.5" Loco and it went really well. I got to thinking I'd like a nice 3.5" gauge locomotive. Browsing the interwebs, I saw an advert on the http://www.classifiedsteam.co.uk/ for a part built 3.5" Gauge Britannia with boiler. It looked nicely built so I arrange to visit the seller in Uttoxeter. Lorna was the daughter of the man who started this loco. The late Alfred Cyril Beardmore had started an apprenticeship with his father making Clocks and Watches but eventually moved into slightly heavier engineering at Avery in Birmingham eventually ending up as their Chief Engineer. He is co-inventor of a mechanical measurement patent : https://www.google.com/patents/US3647010. Here is a picture of Lorna and Cyril at Great Central Railway in front of 70013 Oliver Cromwell. Cyril passed away in 2011. A visual inspection showed the work to have been t...
Read more

What did I buy....

Image
Here's a few pictures showing the loco as I bought it. I mocked up the boiler and plate work to get a feel for what it looks like. I hadn't appreciated how high the cab sits.  Tender is less complete than the loco wheel castings are un-machined, its genearlly a good idea to let iron castings rest for a while I think 50 years should do it! The grate and ash pan assembly sits a bit high at the moment so the boiler barrel doesn't quite sit level.  Paint is in good condition so will just need the odd bit of touching up. Only centre section of grate can be dropped. Nicely detailed trailing truck. I will engrave the B.R. TIMKEN logo on the bearing caps with my pantograph engraver. I'll do this when I do the same to the Tender Axle boxes. Boiler appears to be very well made.  Not sure which design of regulator was chosen Curly provided two different ones. May change to my preferred PTFE lined commercial valve. ...
Read more

Axle Box Timken Covers Part 2.

Image
A distinctive feature on the Timken covers is the four studs with accompanying nuts. I decided to add this feature to the axle boxes using dummy 12BA studs and nuts these would be glued into each corner. I ordered some 12BA nuts and bolts from EKP supplies and tried to figure out how to use the Pitch Circle Diameter feature of my milling machines DRO. After a bit of head scratching I realised the DRO has to be in ABS mode which is effectively the base measurement axis (the DRO supports different 100 axis or rather 100 different origin (0,0) points. Once I figured that out I used a centering indicator to line up the first axle box. Here I'm checking right to left its within 0.1mm Next job is to set up the DRO. Axis 00 selected (ABS Mode) The X and Y axis were Zeroed using the Xo & Yo Buttons. PCD Mode selected, Centre is same as ABS centre, hit down button. Pitch Circle Diameter is next, 14.27mm was scaled from a photo. Relative to the di...
Read more