It feels a bit like the old maths question at the minute - there are three steps forward, and two steps back again. The bogie artwork is currently undergoing another tweaking, but I'm hopeful that the mark 3 version will be the final version, as I've just about discovered everything that could be improved upon, I think..
It's mostly little things, like adding a couple of extra positioning holes on the parts that are soldered on to the mounting plate, but the frames have required a complete redesign. In this version, the axlebox guides will be soldered on to the main frame, with a spacer between to pack them to the right distance inside of the frame.
As a part of the final redesign, I've been assembling the various parts, to check that everything works as it should. The following photos show the secondary suspension mount, with the original trial spring in place.
Since taking these pictures, I've realised that the prototype spring is too powerful - it needed a force of 500g to compress about halfway, which I think means that the 37 would need to weigh 4kg for it to work as intended! I've since cut the prototype spring down to 7 coils, which reduces the spring force greatly (I'm not sure how much by yet, I haven't measured it). I've got some thicker copper wire on order, so will see what that's like, as I think that the brass might still be a bit too springy.
This shows the revised spring length for the secondary suspension, alongside the first prototype primary spring, made from copper wire. I'm not sure if this is final length for this one, the revised frame etches need to be constructed first, so I can work out the height of spring required.
The remains of the moulded springs on the kit sideframe, will be turned into locating studs for the primary springs. i had originally planned to replace the equalising beam mounts with an etched part that would actually pivot, but have abandoned that plan for now. I will give it a go at a later date, but with a suitable casting, the etched parts don't look as good as what's there at the moment.
This funny looking part:
Rests on the secondary springs, whilst also locating the bogie on the pivot. There will be some form of screw adjustment incorporated either into the supports that rest on the slide plates (see next pic), or from the secondary springs to the bolster to give the ability to adjust the ride height.
The slide plates and the bolster bearing surface can be seen in the picture above. The plan to stack etched washer-like parts isn't quite working - I need more than I've planned for in the etch, so this will be replaced by a turned brass part of the required diameter, once the next version of the main etches are back, as I don't know what length the part needs to be to maintain the correct ride height at present.
The final picture shows the mounting plate in place on the bogie, but it is too close, as mentioned above.
There's a few more parts to test this week, then hopefully everything that needs it will be amended by mid-week, so the revised file can be sent to the etchers.
More soon, with any luck
9 Comments
Recommended Comments
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now