Monday, 15 February 2016

Boxpoking about


So what have I been upto since my last post I hear you all ask. Well, I have been mostly CNCing stuff.

I have a Dapol Q1 which has been treated to a conversion a while ago. For those of you who remember it I ended up writing an article for the Model Railway Journal which ended up in issue 211. The problem was that I was never happy with the results. While the engine did run it wasn't upto my standards as the wheels were a kind of hybrid of dapol and 2mmSA.

As with many things in life, the older you get, the more knowledgeable you get and this is a classic case. Since my last attempt at conversion I have rethought an approach to producing the wheels for another attempt at getting something I am happy with. This time armed with a CNC mill I made a start...

This is how the wheel started off. A 3D model of a scale wheel with a 2mmSA rim attached, from this I can generate a CNC programme. In my previous post I showed how I turned up the blanks from Paxolin and added the association rims.

The wheel blanks were clamped in a rotary table and clocked with a dial test indicator to ensure they were centred correctly. I had a frustrating time getting the DTI to fit the milling machine because of the depth on the Z axis wasn't enough. This meant I had to make a little bracket (seen clamped to the mill chuck) which was a pain.
Once the wheel was centred the programme was then run. The milling cutter is a 0.5mm slot drill which conveniently was suitable for all the milling and drilling operations. The programme took about an hour per wheel. It seemed to take forever to do all 7 (6+1 spare) spread over a number of evenings.
And these are the result to date. The backs need tidying up a bit on the lathe but other than that the next step is cutting some axles and fitting them to the chassis.

Am I happy with them? Definitely, they look like Boxpok wheels and fingers crossed they are an improvement on the previous attempt.


Tuesday, 2 February 2016

Not gone, back once again.

Hello Folks.

Wow, was it really October last year when I made my last blog post? Doesnt time fly when you get on with things. With many of my other projects, enthusiasm comes and goes, thoughts appear and ideas are tested. To be honest the vast majority of the time it doesnt feel like I have enough to warrant a blog posting so instead of waffling on about nothing in particular I do try to save up things a bit to hopefully make the blog posts interesting.

So, what have I been upto since my last blog post I hear you all ask? Here is a summary of the bits and bobs I have been playing with, it might be interesting to some? I really hope at least a single person gets some inspiration from it all...

1. GWR 22xx

 This has been a project that has been ongoing for a bit now. I restarted it over the Christmas break as the layout was once again packed away for the festivities. As per pretty much all my projects the starting point was a scale drawing which was then added into AutoCad where the size, shape, and gearing was worked out. In the particular case of these engines the CAD drawings were then imported into Inventor (my 3D package of choice) where I have a nice little plugin that converts the 3D into G code ready for my CNC.

This is the setup. As you might realise from the majority of my photos my workbench is basically my PC table so when the machines are out the PC takes second priority.
This is an image of the CNC chopping up some PCB material. In this instance its a sideframe for one of the tender chassis. The cutter is a 1mm diameter Carbide slot drill (for those who are interested!
Once all the bits I need are cut out its then a case of soldering the bits together as per a etched chassis. They are accurate enough not to be reliant upon the axle holes to line everything up.
This is the resultant of the tender bits an bobs to date. The motor is a 2MMSA component. These two chassis are destined for a dapol 22xx tender body.
And this is one of the chassis to date. There is still lots to do which I work through once I have figured out what to do. Its the first tender engine I have built replacement chassis for so there are new challenges for me. I have designed a little bracket on the engine that means the worm can be easily removed if needed, to me its an essential part of a chassis.

2. Q1

I have decided to remake the wheels for my converted Dapol Q1 engine. The originals didnt run as concentric and wobble free as I would have liked so I have made a start on a new design.
The first part of the idea was to turn up some wheel blanks which use standard 2mmSA wheel rims. The blanks are made from a Paxolin type of material bought on Ebay, the rims are glued into position with a spot of loctite.
These are the blanks to date ready for profiling. The three on the right are scrapped parts which didnt 'turn' out right (it happens) and as you might have noticed I have seven passable wheels so there is a spare just in case of future errors.

More will follow on this as I make progress.

3. Mamod

A bit of a curved ball this one but at a toyfair over the holidays I picked up this for the total sum of £35.
The original thought for this was to replace the chimney and lave it at that but of course its changed now. As my confidence with the machines I own is growing the ideas are starting to develop, so there are some small plans for this now. It doesn't involve making a chimney though, does anyone know where I can find one?

4. P.C.

OK, so not modelling but worth mentioning. Over the holidays I invested in a laptop PC. This is a departure for my as previously its always been a desktop PC. The BIG advantage is that I now have CAD-TO-GO and recently tested this out at the ST Albans show where I demonstrated my CAD work. It seemed to go down well so hopefully I will be doing more of this at shows in the future.

Right, I think thats this blog up to date now. Let me know what you think...

Julia :o)