Member postings for Andy Ash

I was never trying to sell TC. You should use whatever CAD system you want to. If it helps to understand how bad I actually am, I'd have done way less 2D layout if it had been an intermediate task. Nigel did mention that he likes 2D TC techniques, and I hopefully demonstrated that there isn't a massive gulf between 2D and 3D. Maybe people would still disagree with that, but I don't think they're even vaguely separate things.

It is fair to say that I do many more 2D drawings than I do 3D ones, and I actually make money from those. That's because most things I get made, are in sheet metal. I think if I had a five axis machining centre on tap, I might think differently, but not everything useful comes from a billet. As it is, I mostly use the 3D modelling for the 3D printer.

As an example I'm making a battery mount for a Chinese micro camera. It is 3D printed but is like a plastic moulding. That was just completely different in the way it arose. With that I did a model of the camera, then I took an imprint from the camera model. After that I just created the battery compartment and the passages for the wiring and spring contacts.

I don't really mind about how critical people are of my CAD skills. Nor my bone headed persistence for using a tool as bad as TC. Really, it doesn't feel like a chore. I don't really have any set way of doing things at all. I just have an idea in my head, and it expands out to suit whatever. For some people it's about creating a perfect CAD model. I don't really want to be the best CAD person in the world. I just want to make stuff. If you're doing patterns for castings, it doesn't even matter if the model is a bit wonky. If you're making something from solid on a manual machine, the 3D model is all but useless.

What I disagree about is that 2D is a bad, old, passe or irrelevant philosophy. That's like saying that the teachings of Euclid or Pythagoras are no longer important. Know your first principles, because sooner or later they will serve you well. More important than that, don't think of CAD as an end. If you really need to create a 3D model so that you can get 2D dimensions, think of that drawing output as the beginning of actually making something. If you do, sooner or later you won't need a 3D model, you'll just see it in your head. You might not even need a drawing. The less drawings you do, the more stuff you get to make and test!

It's not how good your drawing is. It's how well what you drew actually works. Even failure isn't bad, because if you fail, you make it better the next time.

Edited By Andy Ash on 15/04/2023 17:46:59

Hi Nigel.

Don't lose heart. I've no interest in selling TurboCAD but if you want to do it that way, I'm sure you can. You mentioned about the assembly of a crank, so I thought I would draw one up and make a vid out of it for you. I'm pretty sure there isn't anything here that requires the platinum features of TC.

I use TC 2016 Platinum. I have had no desire to upgrade to a newer version, but I always keep my eyes peeled for second hand deals. People do want to move on, and when they do, they can get something for their old licence. I just had a look and TC is cheaper this year than it has been previously, so perhaps they're yielding. Maybe at the price I might be tempted.

The one thing that I think my version of TC lacks is kinematics. The modern CAD packages do that in the blink of an eye, and I wonder if that is why the price of TurboCAD is yielding. It isn't critical for me, I just need to be able to model solids. I work out loci and envelopes by other means, but I'd be keen to use it if it were available at a price I could afford.

Edited to add;

I was just looking at the current annual price not the perpetual one. It's the way they lay out the website.  I wouldn't buy the annual licence, and the perpetual one is more than a 1k GBP. I couldn't justify that for the use I will give it. For 1k GBP I'd expect the kinematics to be there, but lots of people don't need it and will make money using the software even without it.

I still like the way TC works though. I suppose it's just that I've been using it so long.

Edited By Andy Ash on 12/04/2023 20:34:06

When you draw a 2D line, it goes onto the current WP. You can happily do a valid 2D drawing looking at the surface of the paper as if it were on top of an isometric cube. You ask to draw a square, but it looks like a rhombus until you view it from above like a 2D drawing. There can be multiple WPs in any drawing at any time. In principle there can be as many WPs as there are 2D entities. Although you can define specific (named) WPs there is no actual need to explicitly define them at all.

To qualify as a 2D drawing, the general TC3D drawing must contain no 3D entities. Moreover, there must only be one WP on which all those entities exist. In my mind at least, the angle at which you view the 2D drawing does not change the 2D/3D status. If there is more than one WP or a 3D entity, it can no longer be fully represented on a sheet of paper. A 2D drawing is a special case of the general 3D TurboCAD drawing.

TC tracks every 2D object drawn, it remembers which WP a 2D object is on. if you are just casually editing a drawing and there are two different 2D objects on different WP's then TC will switch the current WP automatically. When you add a new 2D object, it will go into the drawing on the WP of the object you last touched. Touched, means snapped to, moved or selected etc. If you don't have the red guide plane switched on, you have no way to know where the current WP is unless you keep track in your head.

There are issues with this. If you don't realise, it's like the world of TurboCAD has gone nuts. Nothing seems to be right any longer. This is worse than a TC bug, of which there are some. It feels like a major headache because snaps go to the wrong place. Lines jump in random directions. Haywire!

As you get used to it, you get a sense of when the software is going to switch planes. From time to time you realise that the WP red lines aren't switched on. Sometimes they vanish on their own. I don't know why. I think that's actually a bug. Gradually you find yourself able to know when the WP will and won't be working in your favour. It becomes easy even though the WP red lines aren't there. Sometimes now I even forget to switch them on, until I get into something more difficult.

When the WP is not where you want it, there are lots of different ways to control where it goes. You just need to remember that once you set the WP explicitly, you mustn't touch anything that might not be on your intended new WP. If you do, your explicit selection disappears. Once you draw one 2D entity onto a new WP it is easer because others will tend to go onto that WP on their own. You can almost think of the WP as a semi visible cursor for 2D entities in a 3D space.

Once you master the WP, the 3D selector will feel like a gift instead of a burden. I can see from what you said, you have an excellent understanding of the 2D selector. The 3D one is identical with one truly beautiful difference. Snaps on 2D objects only work on the same plane as that of the entity that owns the 2D selector handle. Snaps with the 3D selector handle work anywhere in 3D space. If you select snap to intersection and use the 3D selector, you can move a 2D object onto an intersection between two lines on another WP.

Apologies in retrospect for typos!

Edited By Andy Ash on 11/04/2023 22:42:37

Hi Nigel. I would say that you have got a pretty good handle on how TC works. I wouldn't maximise my own abilities beyond saying that I've been using the thing for a long time, but not continuously. If you were to divide my knowledge amongst the years it has taken to gain - I don't think it would leave me looking very good.
The strange thing is that I read what you are writing and I can see exactly the same barriers I had in the descriptions of your own difficulties. I thought it was just me, but from what you are saying I think now it is probably the tool.

The one thing you said that stood out was that switching from 2D to 3D mode sends everything haywire.

I remember that, really well. TurboCAD in the early 90's was actually two different software applications. 2D and 3D. You couldn't even move a drawing from one application to the other. You had to decide of you were going to do one or the other. If you changed your mind, you had to start again. The separate 3D software was virtually unusable in an era where the humble mouse was only just emerging for ordinary people. The mouse-wheel no-one had ever heard of!

I think the 3D software then was the basis for the whole package now, but it didn't have the 2D capability originally. Counter intuitively the 2D software didn't look any different back then as the current software does now. It has been steadfast. Although people were using the original 2D software I was one of those that didn't realise that the 2D behaviours were added to the 3D software. From memory the 3D software didn't get the 3D selector until the 2D behaviour was added to it.

It is really important to think that the modern TC software model space is just one thing. That world plane, is just one in the 3D space. You can put the plane anywhere you want. Any angle, any position, anywhere in the 3D space. Even if you only ever do 2D drawings, they are 2D in a 3D space. If you only know about 3D then someone can take your 2D drawing and leave you looking at a single line. Your drawing is still there, but you're just looking at the edge of your drawing.

There is an option that causes the workplane (WP) to be drawn in to your drawing as a red dashed line. It doesn't matter how you zoom or angle the WP, the red lines represent a square drawn on the surface of the current WP. It is important to realise that you can move both the WP and your view of the WP. If you look obliquely at the WP then the square is drawn obliquely. The red lines don't actually exist in your drawing. They're just drawn in like a laser light that you can just turn on or off.

Contd.........

I have a Potterton Netaheat that I have been "nurturing" for three decades, and I can confidently say that the boiler control lasts for fifteen years before it needs fixing. I conducted the fix twice in the same way, and it worked both times. I do now have a spare controller which I swap in when it fails so I have time to fix the old one and keep the newer one at "low hours".

Like John I reverse engineered the controller, and made all those discoveries. I've included the schematic I extracted below. I never thought anyone else might benefit from it, so I never posted it.

The main problem is that C2, which is an electrolytic capacitor, dries out. The flame sensor circuit is very sensitive, and it depends on a smooth DC rail from the mains to work properly. When the capacitor dries out, the supply has too much ripple and the circuit can't see the tiny (around 1nA) flame current.

The world is going to the wall, unfortunately, as we all know. I've been looked at getting my trusty boiler working from a battery and an inverter. As we know security of power provision is looking a little feeble over the coming few years.

With this boiler control the flame sensor depends on an earth connection and it needs significant capacity. If you run the boiler from an inverter you will find that the flame sensor fails even though the pilot is alight. To resolve this issue when using a battery inverter you will need to do two things.

1) Ensure that the boiler earth is connected to the physical earth for your property.

2) Connect the inverter neutral output to the earth that goes to the boiler.

If you do these two things, then a Potterton Netaheat can operate from a battery inverter, even when there is no electrical supply to your home. In these circumstances, the law may not need to get in the way of your probable need for basic hygiene.

Edited By Andy Ash on 08/04/2023 11:33:33

I obviously can't say what Nigel does, but in TC there are loads of options for componentisation. If you want, you can create all the components in different files. I don't do that, but occasionally the scope of what I'm doing will change, or maybe I'll steal something from a previous design and use it in a new one. In this sense TC supports cut and paste.

You can cut anything from one document and paste it into another. You will have issues if you cut and paste between metric and imperial drawings, but you can convert the units at the source or destination before the transfer and then there are no problems.

My version of TC happily deals with step models which is quite useful for me because I do a lot with electronic components and most will have a step model of some kind. Also it will deal with dxf and dwg files so models for sheet metal fasteners are usually available online.

Within TC itself, there is an idea of promotion of entities. Lines and arcs combined promote into polylines. Closed polylines on a plane become surfaces. Surfaces can be extruded into solids. Solids can be interfered with one another into ACIS solids.

You can create other kinds of solids outright. Obviously there are spheres,cylinders and boxes, but you can also do donuts prisms and cones. There are also different extrude schemes like simple extrude, rail extrude (using a 3d polyline), spin. Also available is lofting which will interpolate a solid between two different facets.

There are a few "novel" construction tools, but the most useful is the "gear contour". If you want to make straight or helical gears, either DP or Module, you can just fill out a form and it will give you the correct gear outline which you can extrude into a straight cut gear, or twisted extrude into helical or herringbone.

When you promote objects as described previously, it is different from grouping them. Behaviourally it is similar but a group is just a group. You can do new things when you promote objects, but a group just preserves and protects positional relationship between any grouped entities.

TC has two modes of operation 2D and 3D, each has it's own selector. the 2D selector is a reference point and a rotation handle. The 3D selector is a reference point and three rotation handles, one in each axis. The 2D selector is constrained to the current workplane, but the 3D selector works anywhere in 3D space. The 2D workplane can be moved anywhere within the drawing but usually you set it either to a facet of some object or the "world" orientation. If you want you can define a random plane with three points. There are other schemes for setting the workplane.

Beyond groups, there are blocks, symbols and then parts.

Blocks work within a drawing. You might have multiple instances of a screw. The drawing contains a block which is a kind of subdrawing, and can be placed multiple times in the main drawing. If you edit the block then all instances in the drawing change. Then there are external references. These allow you to place another drawing (document) into the present one in the form of a block. External references are somewhere between blocks and symbols, but both are manipulated through the block palette.

Then there are symbols. Symbols are drawings one file per symbol which you can use in any new drawing. These symbols are just drawing files, but they are called up with the library palette. Not that I have tested it, but  think an external reference will update immediately the external reference changes. I think a symbol is different because the entire content of the symbol is inserted into the drawing as a group. You can explode a symbol in the drawing and change it, but I don't think you can do that with a block.

Finally, there are parametric parts. TC supports the Ruby programming language. You can create symbols which have parameters. You could describe a cheese head screw with variable length. You write a program which defines how to draw the screw. When you place the part, it asks how long the screw should be, and that becomes the screw you wanted. Don't ask me how to do this! I think I probably could, but it would take me a while to figure it out.

Ruby is not a programming language I have used. I can't remember what exactly I was doing but I did do something programmatic a while back. For me it was simpler to write a program that outputs a dxf file. I wrote than in C which is the language I use most. It's not actually as hard as is sounds for simplistic needs. I think I might have been laying out logarithmic graduations - like for a slide rule. DXF is a simple text format so it was easiest to generate the lines as a DXF file and import it to TC.

Edited By Andy Ash on 07/04/2023 01:30:23

In TurboCAD, even the free versions have the capacity to render. I suspect it is more capable than the CAD examples shown by Jason.

With TurboCAD you can create textures from bitmaps or with geometric designs. These can then be rendered onto facets. Typically this approach is optimised for accelerated video hardware which will have dedicated texture memory in the rendering pipeline.

This is more than is required for CAD work, but it stems from the early days of 3D graphics where ACIS originated. API's like OpenGL and so on are optimised to deal with shaded triangles, which support virtual environments like flight simulators and video games. TurboCAD also has a range of built in materials which can be attributed to entities and facets to get a quick and dirty rendered output.

In principle TurboCAD is ray traced with flexible lighting and there are several different levels of rendering. Its a whole pile of hassle to set up lighting and for me even to faff around with textures.

The only thing that I'm interested in with 3D is dimensional accuracy. 3D CAD helps me to calculate and define 3D things that I would struggle with otherwise. It is important to me that I can accurately describe the shape of solids. Wireframe is my main render scheme, to do geometric construction and alignment. I rarely need to sell or promote anything, just to get stuff made.

It's much more important to me that I can accurately pick a vertex from the wireframe fuzz, select an associated facet and start manipulating the model on that facet. If I know how to do that with TurboCAD, then there is no limitation about what it can do for me.

If TurboCAD screen captures are rare, then I've uploaded one to help. This is a drawing of a pattern that I did ages ago. I seem to remember I did this one before I upgraded to the Platinum version of TurboCAD, so it is possible. It just takes way longer and life is short.

In your initial post Nigel you wrote 2012, which I think might have been a typo given what you have written most recently. The "newness" won't get you "more" with TurboCAD just fewer bugs.

It's actually quite hard to separate the "bugs" from the "limitations". Limitations vanish when you step up to the more expensive paid versions. I can assure you of that. What I can't say is whether you will be happy. I have been through exactly what you describe. With perseverance I too was able to subtract triangular prisms from rectilinear blocks to achieve 3D chamfers. It took hours, and frequently the software would crash because I would push it right to the edge.

After I paid for the software I could define a 3D shape in moments. Then I could pick the edges I wanted fillets for. Click confirm, and it fillets those edges and calculates what to do where different kinds of edges meet. You can draw a spline convert it into a surface and use it to slice a mesh. You can do a 3D polyline rail extrude and subtract it from the middle of a solid. It just works, but it is expensive.

Occasionally (every few months) I find myself in a knot where I'm not quite sure where I am. I'll not know if it is me or the software. Things are certainly odd, but I'm not sure if there is some aspect of the software I don't quite understand, or if I'm actually looking at a bug. I save fairly regularly and I use Git version control as well. It's not a big deal to backtrack and redo. Usually that sorts everything out.

I have had the paid software crash on me, but as I have become more systematic in my use it seems to have become happier with me! It must think I'm improving.

I cant say relatively if other CAD packages are better or worse, but I have used sketchup and and I hated that. I don't like Fusion360 but it is massively popular.

A 3D mouse is great for flying around your model. It's basically a six axis joystick. You use it in addition to an ordinary mouse. As things get more complicated, typically you will be working with a wireframe even if you plan to render your final object. Wireframe is as good as it is horrible. Wireframe is great because it is like x-ray vision, but it's horrible because it's like x-ray vision.

The 3D mouse really helps because you can look at the model as it moves. When it is static you can see it both inside out and the right way around. Once the model moves it is much harder for my brain to see it inside out or upside down. Also it is quite common to get nodes in the distance which overlap ones that are nearer. The 3D mouse will help you separate snap targets without loosing your focus on your objective.

Edited By Andy Ash on 05/04/2023 21:08:29

Hi Nigel. Sorry I didn't respond earlier. I did spot your post a couple of days back but I've been busy with work and I didn't get a chance to reply. I'm an avid TurboCAD user of thirty years. I like it because of the way it works but I also recognise that the 3D capabilities can sometimes be frustrating.

I'm not so keen on constraints based CAD, and I much prefer the faceted Euclidian approach that you get with TuboCAD. I'm told I'm a dinosaur, but it's fine - I will be dead soon so perhaps they're right.

The thing to understand about TurboCAD is that it is two modelling systems that have been merged. IMSI have their own 3D system, but it has some limitations, so the full 3D capability is a Dassault (I think) technology called ACIS. The two schemes are merged in the software so you don't notice unless something goes wrong.

The ACIS part is where all the cool stuff like 3D fillets, meshes, 3D boolean operations happens. If you have the cheaper "lite versions" you dont get ACIS and it feels like your skills are lacking. Actually, you can confidently blame the tool! Once you use the expensive version, the difference is known, and you realise all the cool stuff you wanted to do without difficulty.

You don't need a 3D mouse, and it won't work with earlier versions (mine is 2016). The 3D mouse helps though because you don't find yourself "scrabbling" with the mouse all the time.

I got the licence for mine (Platinum Pro) second hand on e-bay which was a considerable saving over new, but it was still a couple of hundred quid. At the time I bought it I wondered if it was wasted money, but I find I have no limitations on how I can use my 3D printer (aside from the printer itself), so I think it was well worthwhile. I was worried that the licence might be pirated, but I did some research and it was clear that it came from a defunct design outfit up in North Kent.

In specific answer to your question I was able to create a box. Then I switched on the shading with the teacup. Then I created a view looking on the corner at an angle. I created a viewport in the paper space looking at the corner of the box. The picture on the printed page was a wireframe. I selected the viewport and went to properties. In the "rendering" item of the tree control in the properties dialog, I changed the option from "wireframe" to "quality" and I got a shaded box in the viewport on the printable page. I hit print and sent the job to a PDF writer, and got a PDF with a shaded box.

Because of the age and the limited nature of your software version (not pro) you may not have the "quality" option that it sounds like you want.

Edited By Andy Ash on 05/04/2023 16:50:03

Edited By Andy Ash on 05/04/2023 16:53:49

Groovy baby!

(It's the pink satin that gives it away!)

Edited By Andy Ash on 05/03/2023 22:25:57

I'd probably give that a miss myself, but it takes all sorts I suppose!

People these days have forgotten what production was about because they have been spolied by CNC.

I know a Myford 7 is seen as expensive these days, but we (usually) don't think about making money with one. CNC wins that war every time.

In the old days the Myford was a fairly economical machine. If need be, you could buy one and cut it in half if you needed to. In that form you could bolt some other stuff to it, and -voila- You've got yourself a special machine for hob throbbing nibbly widgets.

I've worked at two different companies making electrical and switchgear equipment where they used a Myford 7 as production equipment.

One place we had it for second operations after the parts came off the capstan lathe. That company made microswitches.

The other company made electrical safety testers. There, the Myford was used for finishing and modifying plastic (phenolic) parts. They had a standard moulding for the high volume product. There was a low volume product which needed a different but similar shape. It was easier/cheaper to modify the high volume part into the low volume one on the lathe, than to make a whole new mould tool.

My previous Myford came from a switchgear company in Croydon when they closed in the 1980s.

I can assure you that Myford 7 lathes were used in many many industrial settings.

It was the pukka deal in small instrumentation/gauge manufacture and repair work.

@DMB, Well I just had twenty minutes to try and find out a bit more about the scissor gear, but I'm still none the wiser. I had heard about it before but I don't think I have ever seen a picture or diagrammatic representation.

As far as I can tell it was fitted to North Star. As a four cylinder engine, I imagine it would be what I would generally describe as a "conjugated gear", where the valve motions of some cylinders are generated from valve gear directly set for another cylinder or cylinders. The mechanics of the conjugation may look like a pair of scissors.

Indeed I think I had thought that scissors was gab, because someone had said that to me a long time ago. Probably like forty years ago if I'm honest. Gab certainly looks like two pairs of scissors, back to back. That was probably enough for me at the time.

Today, there does seem to be some suggestion that Churchward and Deeley had a bit of a thing about Midland railway patents in relation to valve gear. Perhaps those dodgy early Midland railway engines were the origin of the mysterious scissors.

I suppose one must be particularly intent to go searching for the geometry of a potentially difficult valve gear. Personally, I have long since moved on from the time where I try to improve my own bogus efforts. For what it's worth, I learned it was easy to come up with something bad, and even harder to make it better! Nowadays I just try to make whatever it was work O.K. That's enough for me, if I am lucky enough to succeed.

If anyone has a picture or a diagram showing what scissors actually was I would be quite interested to look, if only to relegate my mental image of gab gear. I understand there is a picture in the Martin Evans book. Maybe one day I'll buy it, but I always was more of a Curly fan than a Martin Evans one. No slight to Mr Evans of course, a nice person and an exceptional engineer for sure.

I'm pretty sure many of the full size engines had really odd arrangements. Some probably never even had names. I think the scissors gear is also known as "Gab Gear". Joy gear, is one of the most fiddly to get right, but also one of the most useful if you can. Baker is pretty practical. The Bullied chain driven gear probably wasn't.

Some early Midland and North Western engines had valve gear with a bad reputation. From what I remember the Midland Compounds were pretty terrible.

Probably my favourite arrangement is "Bagnall Price". That has an "expansion link" that appears to operate counter to all the links around it. Actually there is a crank inside the frame which can't be seen at first glance.

For dogmatic reasons modern approaches were resisted in England for a long time. With the advantage of modern thinking it is now obvious that cam operated valve systems like Caprotti had a significant technical edge. I think some of it was the difficulty of making the necessary bevel gears and cams compared with usual simplistic railway locomotive components. There are plenty of examples of complex components in other industries of the time, so dogma must have been a significant issue.

By the time of the BR standards, engines had become so complex anyway, that such technicalities as Caprotti gear happened with relative ease. At the time, I'm not sure that Caprotti really outshone Walschaerts from a performance perspective. I think if this generation of engines had reached their proper service life the cam operated gears would have shown significant performance benefits with less maintenance.

Hopefully that's a less technical response.

I still think it misses the point because it is a bit disingenuous. The exact placement of the pivots and method of support for the expansion link in Stephenson's, Gooch and Allan gear makes a huge difference to the performance of the engine. There aren't enough names (I think) to cover all the potential possibilities.

Edited By Andy Ash on 27/12/2022 22:03:46

I think there are four angles that you have to think about.

Two are the rotation of the spindle axis centreline within the head. The other two are the rotation of the linear travel of the head relative to the machine as a whole. If everything was true and square, your hole would be round and not tapered.

The ellipse comes from a misalignment of the spindle axis from the hole axis. The hole taper would probably be a complex combination of machine truth and head truth.

Some of the four angles won't easily be adjustable, but don't forget that once you understand the limitations of your machine, you can use shims to bring the work into alignment with the machine. Ideally if there is a reference face on the work that is parallel with the hole, you can use a dial gauge. Just pack the work with shim stock until it is in alignment with the undesired axis features that cannot easily be adjusted.

In the end a straight line is a straight line. If the machine is not tight, but not loose either then it is likely to produce a pretty straight line from a single axis. That's all you actually need. If you use the vertical axis instead of the quill, you have more problems because the head might be "nodding" rather than "swaying" and you can't usually correct the nodding angle.

If you can just use the quill, then you can pack the work until it is true to the quill.

I too have a Chinese mill!

Hope you get the hole you want.

Edited to add;

Actually I should also say that I'm presently using the boring head in the lathe for exactly this reason. I have less range of movement in the lathe, but the machine as a whole has better truth.

Edited By Andy Ash on 27/12/2022 18:31:59

I have come to the conclusion that the generic valve gear names are useful in casual conversation, but not for much more. The complexities of building a model locomotive valve gear are many. Generally one has to think of them as highly imperfect compromises.

Probably, some designs are better than others. If you're actually going to build it, you have to check the design you have before you use it. The devil is in the detail, and every detail matters. One detail that makes a big difference for example is suspension travel, and no-one ever seems to think about it.

Don Ashton's simulator is good and interesting, but it is less useful when it comes to simulating an actual valve gear implementation, because the details are frequently different. It can be hard to get the Ashton simulator to match one's own gear exactly. Many CAD tools support kinematics, but they can be expensive. If you want a free kinematics tool which is very good, you could try;

https://blog.rectorsquid.com/download-linkage/

I have no affiliation with this tool, but I have used it and found it to be good. For me, I found that the sliding length of my expansion link wouldn't be long enough to clear the die block for all reverser settings. The crash was only 10 thousandths, but enough to make the expansion link bearings wear excessively.

Obviously the linkage tool won't do steam diagrams, but for a model I think that is all a bit academic anyhow. If you can make all the parts fit properly and perform their generally intended functions, you won't go too far wrong.

With the kinematic simulator you will be able to see why the gear behaves differently in forward and reverse. You can also experiment with the static settings like eccentric and valve positions.

I'd vote for Comsol as well. It only melts at 300 degC, but that's plenty enough for cylinders. Being a higher melting point than 60/40 it retains more strength at higher temperature.

The only problem you might have with Comsol is that it requires a different flux from 60/40 and pure tin. Most leaded and lead free fluxes only just make it to 230 degC. For Comsol you need "Bakers Fluid" which is otherwise described as a Zinc Chloride flux.

Don't get the flux on anything other than the work. It rots just about anything it comes into contact with, and is a devil to get rid of. It will dilute in water. On steel it somehow penetrates into the surface, such that reoccuring rust appears where none did before.