Mk2 Lever frame musings

Discussions of the prototypes and how to model them. Show us how you do it.
JFS
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Re: Mk2 Lever frame musings

Postby JFS » Tue Dec 04, 2018 10:52 am

Just a bit more progress to show on the Leeds City Wellington frame. All that remains is to make and fit the locking bridles and cut the ports in the tappets...

Wellington Frameno locks.jpg


Meanwhile, the locking design is now up to version 5, though I feel this might just be THE one...

Here is the box diagram for anyone wanting to have a go...

Leeds Wellington Box Diagram v1_2 paper resize.jpg


Best wishes,

david_g
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Re: Mk2 Lever frame musings

Postby david_g » Wed Dec 26, 2018 11:15 am

Howard,

A few observations/questions about the lever frame and locking bar assembly:

Firstly both etches are a joy to build, go together easily and are quite addictive, having completed one section you just want to crack on with the next.

The lever frame even survived a couple of my ham fisted efforts, as a warning to others they were:

Be very careful forming the loop at the top of the catch rod, on one of mine I bent the half etched section once too often with the inevitable result that it snapped off. Repaired by forming a loop from some brass fret waste soldered both sides of the catch rod with the 0.6mm wire through the loop.
Soldering one of the catch boxes to the lever resulted in the catch soldering up solid. Frantic wiggling of the catch handle while applying the soldering iron to the catch box managed to free it off though it is still a little stiff. I'm wondering if working the catch handle with a little Brasso down the catch box might free it right off.

The instructions warn against both of these so my fault for not being careful enough.

Now the questions:

In the locking bar instructions p14 it says the initial target for the width of the crossheads should be 6.5mm; mine were nowhere near that to start with and after repeated measuring with vernier and steel rule I concluded this is a typo and should read 5.5mm. Am I correct? Forcing them into the slots in the cam plates requires a certain amount of faith and has left the finished sizes of my crossheads at around 5.4mm to prioduce a good sliding fit.
Similarly the cam plates have finished up around 8.75mm not 9.75mm as in the instructions p16 and didn't start that wide before I attacked them with a file. Another typo?
Finally the cam alignment jig instructions say use 1.4mm brass wire or tube to open the slots in the alignment jig. I've used 1.2mm tube which is very tight. Before I force 1.4mm in there I wanted to check this is correct.

A couple of photos of the state of play attached. I haven't fitted the drive pins to the levers or crossheads yet as the only thing I have to cut the piano wire is a 4.5" angle grinder which would be a little brutal and risky. I have gone for method 1 for the tappet assembly as the locking hasn't been worked out yet; that will be the next question after I have built another lever frame/locking assembly to extend the frame to 10 levers.

David

IMG_0186[1].JPG
IMG_0187[1].JPG

JFS
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Re: Mk2 Lever frame musings

Postby JFS » Wed Dec 26, 2018 10:58 pm

Hello Dave,

Firstly, many thanks indeed for the kind words re-the etches, and well done for making a great job of it judging by the photos. You might also be the first one to post a pic with the turned handles and very nice they look as well.

Now to your queries on the dimensions, regarding the 1.4 mm slots in the cam jigs, this is a simple mistake on my part as there is no such thing as 1.4mm brass wire and it is intended to be 1.2 mm.

Now, regarding the crossheads and cam plates, when I first read what you had written I was fairly sure you were wrong BUT when I checked you are quite right on both counts! What I cannot explain is how I made the mistake as a quick check on the drawing shows it as you have it. And I have only built about 35 of these things... My only excuse is that I never actually measure them as I have two pairs of spring bow calipers which I use... Maybe I should read my own instructions a bit more carefully.

Anyway, I will sort out the corrections to the notes and upload a revised version over the next few days. In the meantime, many thinks indeed for pointing these things out.

Best Wishes,

JFS
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Re: Mk2 Lever frame musings

Postby JFS » Wed Dec 26, 2018 11:10 pm

Just to confirm that I have uploaded a new version of the notes - Dave if you were able at your leisure, to re-download and confirm that I have done the necessary, I would be very grateful.

Best Wishes,

DougN
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Re: Mk2 Lever frame musings

Postby DougN » Thu Dec 27, 2018 1:11 am

David, have to congratulate you on the lever frame it looks great and I hope works very well.

Howard the ability to go and create new instructions and up load is fantastic. This shows the ongoing ability of the society to continuously improve things. :thumb

I have put my suggestions for the Mark 1 on the other thread!
Doug
Still not doing enough modelling

XN593
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Re: Mk2 Lever frame musings

Postby XN593 » Mon Nov 16, 2020 1:05 pm

Is there any interest in another 'Show and Tell' of the Mk2 lever Frame?
Kind regards
Peter

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richard_t
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Re: Mk2 Lever frame musings

Postby richard_t » Tue Nov 17, 2020 7:41 am

Yes please.

Alan Woodard
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Re: Mk2 Lever frame musings

Postby Alan Woodard » Tue Nov 17, 2020 8:16 am

Me also.


Alan.

XN593
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Re: Mk2 Lever frame musings

Postby XN593 » Tue Nov 17, 2020 10:52 am

My pleasure.
Then let us begin.
Firstly thank you to Howard for his skill in producing the kits and Howard, if you are reading this and you see something I have done that is so stupid no one else should follow, please shout out.

I have always had a fascination for mechanical interlocking, a sort of if, then, else, long before computers. My first attempt at making one was over 30 years ago. Made of brass and linked to a Gem Mercontrol white metal lever frame. Not a success. Then, a few years back I made a Mk1 lever Frame (twenty levers) and linked it to a brass interlocking based on the 'Trax 3, Signalling and Interlocking' book. I used standard brass strip which required a specific throw of the lever. In the end, the easiest way to get the throw was to solder a peg to the bottom of each lever which engaged in a slot in the brass tappets. The problem with this solution was the fine line between overcoming the friction of a correctly set route and bending the peg when the route wasn't set correctly. So when I heard of the Mk2 lever with interlocking I knew that one day I was going to have to make one.
Attachments
20201029_154008.jpg
The Mk1 plus Trax 3 frame.

XN593
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Re: Mk2 Lever frame musings

Postby XN593 » Tue Nov 17, 2020 10:56 am

First piece of advice is to read the instructions.
Second piece of advice is to read the instructions.
However, it is only when I started to assemble the kit that I began to fully understand how it really works. By way of an example, the instructions will tell you to solder the rubbing strips to the quadrant plate. There are gaps at the top and bottom of the strips. The top gap is quite narrow and is designed for the catch rod to pass between. What I should have done was to check the gap with a catch rod before soldering! Still, nothing like a few hours with a 5mm strip of Emery paper.
Attachments
20201028_105528.jpg
So get the rubbing strip ends well out of the way.

XN593
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Re: Mk2 Lever frame musings

Postby XN593 » Tue Nov 17, 2020 11:00 am

Another mistake I made was to set up a batch process for all 25 levers. What I should have done was to make one frame with just two rubbing strips and make a single complete lever. That way I would have fully understood how everything works.
20201009_101938.jpg
And so we begin

Pannier Tank
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Re: Mk2 Lever frame musings

Postby Pannier Tank » Tue Nov 17, 2020 11:03 am

Watching with interest, thank you for sharing.
Regards

David

XN593
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Re: Mk2 Lever frame musings

Postby XN593 » Tue Nov 17, 2020 11:08 am

Batch processing. The vice has seen better days!
20201011_134851.jpg


Off come the handles.
20201005_120659.jpg


Holes for the new handles.
20201009_152305.jpg

XN593
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Re: Mk2 Lever frame musings

Postby XN593 » Tue Nov 17, 2020 11:14 am

I made a few mistakes on the way and had two "Oh B******s" moments when I thought a new fret might be required.

The mistakes.
The Catch Rod assembly.

The top of the catch rod is bent around a .6mm wire. It should look like a circle balanced on top of a vertical line. Mine ended up more like a 'P'. Had I realised the importance I would have bought a fine set of needle nose pliers (or tried my circlip pliers that were in the garage!!!!). Why? The catch rod is retained in the catch box. The rod is etched to include two stops that straddle the box and is pulled down by a spring. The top stop rests on top of the catch box. At the top of the catch rod is the catch handle. Because of the 'P', my catch handles don't have enough movement to allow the catch rod to drop down and rest on the top stop.

What gap
20201116_115734.jpg


It's not the end of the world but I was annoyed. It still works but it's one of the reasons for making a single lever before batch production.

How not do do it.
20201012_135653.jpg

XN593
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Re: Mk2 Lever frame musings

Postby XN593 » Tue Nov 17, 2020 11:17 am

Oh B******s - Part 1. THE CATCH BOX
Or "why you should re-read the specific instruction before starting a new section).

The instructions say "Brave souls may carefully reinforce the fold with a minimum of solder…".
I was brave but stupid. The first catch box was ok, the second no so much. Locked solid. With a bit of heat I did manage to open the catch box and release the catch rod. Then I read the instructions, again. The Brave souls quote referred to the catch handle, not the catch box. And if you think about it, the catch box is retained by another method and didn't require my intervention with a soldering iron.
I did not take a photograph!

XN593
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Re: Mk2 Lever frame musings

Postby XN593 » Tue Nov 17, 2020 11:27 am

Oh B******s - Part 2
I had decided to use the turned steel handles. So I cut 25 pegs, drilled a number of vertical holes in a block of wood and using Carr's Brown soldered the pegs into the ends of the handles. I assumed solder would flow down the peg.
20201007_110617.jpg


It was only later that I noticed some of the pegs stuck out more than others. It seems I had created a piston. So I re did the soldering, this time with a downwards force on the peg
I then soldered the handle to the lever and cleaned up with Emery paper wrapped round the handle. Oddly, some of the handles rotated. It would appear I should have tinned the peg first.
Now I have a lever soldered to a tinned peg (i.e. thicker) which won't fit into the handle. The solution was to clamp a piece of wood to the bench, hold the handle against the wood (horizontally) and apply pressure through the lever whilst touching the peg with the iron.
Anyone guess what happened next?
My horizontal pressure wasn't square. The handle flicked off and......
OPENED UP THE END OF ONE OF THE LAMINATIONS.
The top 5mm of one side was bent out at an angle of about 30°.

In the end, heat and pressure eased the lamination back and now the levers are painted you can't tell which one it was.
The annoying thing was that the block of wood used as a stop was the one with the holes in from when I first soldered the pegs to the handles. All the others were done in the vertical plane.
I did not take a photograph!

How stupid can you get?
20201021_125449.jpg

XN593
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Re: Mk2 Lever frame musings

Postby XN593 » Tue Nov 17, 2020 11:31 am

A few other jottings.
I had a piece of aluminium angle (2" x 2" x ⅛"). It's not really wide enough so the micro switches have to be held down by just two screws not four. But it has the advantage of rigidity and hopefully will take up less room on the side of the layout. On the other hand there is a lot of 8ba tapping! As an aside, I tend not to throw much away. When making my older brass Interlocking I had to shorten most of my BA bolts by about 5mm. If you look carefully you will see plenty of these offcuts (studding) used on these frames.

Dimensions.
This goes back to having a full understanding of how things work.
The length of the drive pin (piano wire) must be between 3.2 and 4.0 mm. Any wider and it won't drop through the quadrant plate.
If you are using more than two banks of micro switches, the 8ba rod cannot stick out by more than the thickness of a nut.

The same goes for the main pivot pin. The instructions say "Cut a piece of the 2.5mm OD brass rod to a length of 48 mm". Any longer than 50mm and you are into the next unit. So why did I make mine 49.5mm? I decided to use split pins (similar idea to Colin Parks earlier in this thread) to hold the rod in place and needed a little extra room for my drilling jig.

This rod was rejected as I failed to notice the first split pin wasn't vertical.
20201014_110105.jpg

XN593
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Re: Mk2 Lever frame musings

Postby XN593 » Tue Nov 17, 2020 11:43 am

Most of the assembly was done using jigs, even the fitting of the brass lever numbers.
Difficult to see but there is a very fine drill between the base of the number and the jig to create a break. It stops the jig and the number plate becoming one. There is also an end stop to the right, against which is the drive pivot pin. It stops to the lever moving to the left.
20201024_113356.jpg


I used two drawing pins either side of the catch handle to open out the brass rod, with one touch of the hammer. However I did use pins that had a cone shape as most drawing pins have a four sided point.

20201114_112838.jpg

XN593
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Re: Mk2 Lever frame musings

Postby XN593 » Tue Nov 17, 2020 11:49 am

I hate painting.
I used Halfords (acrylic?) rattle cans over a grey primer (not the plastic primer). Masking was done with Tamiya tape but a lot of the time the tape pulled the primer off. Should I have used their etch primer first (I had assumed etch primer was for brass)? I used their chrome paint for the handles which is an enamel, takes ages to dry and even now wants to take your fingerprint if you go anywhere near a handle.

I should have painted the catch rod before assembly and only down to the top stop.

I should have painted the handles before joining them to the levers and left them for a month, at least, to dry.

I should have bought more countersunk 8ba bolts rather than cheeseheads.

It gets a bit tight down here! Micro switches omitted for clarity
20201114_163723.jpg

XN593
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Re: Mk2 Lever frame musings

Postby XN593 » Tue Nov 17, 2020 11:54 am

Don't bend the hook on the bottom of the catch rod until you really need to. It gets in the way when you want to clamp the rod.

I didn't fold one side of the catch box or catch handle to 90° before fitting, I gently squeezed both sides at the same time when enclosing the catch rod.

If you are using a broach to open the drive pin hole, it took me more than 10 minutes to broach two levers. Then I realised I had some old cutting paste. It took less than 10 minutes to do the remaining 23.

If you are using wooden pegs to hold the laminations together, cut the tips of the pegs off. Your soldering iron can get much closer to the action and you don't need to shuffle the pegs along.
See what I mean? It took me 25 levers before I can up with that dodge!
20201008_140322.jpg

XN593
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Re: Mk2 Lever frame musings

Postby XN593 » Tue Nov 17, 2020 11:56 am

I was lucky with some of the requirements.
I have a pillar drill, tufnel, smooth jaw pliers and clamps, a piece of 10mm plate glass that I use as a surface plate and various other metal working tools.

Piano wire at 90°.
20201019_104001.jpg

XN593
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Re: Mk2 Lever frame musings

Postby XN593 » Tue Nov 17, 2020 12:01 pm

And so we come to the end

One thing I should say, and it's easy now I have finished (Part 1).
It's not difficult but there are times, particularly with a large number of levers, that it can seem quite daunting. But bit by bit there is less and less that needs doing!

As for me, a short respite, then onto the interlocking (with clean tappets) before finally cutting some metal!

So what are you waiting for, you know you want to.

And the finished article?
20201115_164220.jpg


20201115_164428.jpg


20201115_164316.jpg


Kind regards
Peter

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richard_t
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Re: Mk2 Lever frame musings

Postby richard_t » Wed Nov 18, 2020 8:22 am

Hi

Thank you for all that - very interesting reading.

Richard

JFS
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Re: Mk2 Lever frame musings

Postby JFS » Wed Nov 18, 2020 10:37 am

I would add that the quality of workmanship is excellent - much better than mine! And I think it shows that very careful work pays dividends until you have gained confidence from your first few assemblies.

I think the suggestion of fully completing a single lever before dropping into "mass production mode" is excellent and I will look into adding that to the "instructions".

I just have one thought to add - personally, if I were using the separate turned handles (and they are nice), I would polish, then lacquer them as I feel steel takes on a lovely finish when polished. But that is a small detail and in no way a critiscism. One thing is for sure - if they are not coated in something, they will rust - human fingers being what they are!

Best Wishes,

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David B
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Re: Mk2 Lever frame musings

Postby David B » Wed Nov 18, 2020 11:01 am

I put a thread on the top of the lever, used a tap on the handle and screwed them together. A bit of preparatory work was needed - rounding the top of the lever laminations (which I made sure had been well soldered together) before using a die and drilling out the handle before using the tap.


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