Had Another Go

[Michael GilliganParticipant @michaelgilligan61133]

Thanks for that clarification, David

As I currently have neither product, it will be good for me to read both versions

… can’t do any harm that way [!]

MichaelG.

[Charles LamontParticipant @charleslamont71117]

Having read this thread, admittedly not in the minutest detail, I suggest a 3D CAD beginner might be better to start with Onshape.

You can have a free subscription, nothing has to be downloaded run or saved locally, files are kept for you in the cloud automatically, anything you get wrong can be backtracked, there is written documentation, videos, and an active and supportive forum. I think the user interface is better than I have seen from screenshots of other products.

The unique(?) system of assembly constraints using ‘mates’ may be easier to understand

Using it requires no knowledge of matrices or transforms, neither Lapalace, nor Fast Fourier nor any other.

[JasonBModerator @jasonb]

But there are a lot of people out there who don’t want to use the Cloud. Those of us who have spent the last 5 years trying to help Nigel with CAD will know that he would not touch it with a barge pole.

Others worry that if the free software company suddenly disappears then all their work will go with it as it is not stored on their machine and they have no copy of the program. Or a change in the companies policy will see the end to free use and then they either have to pay or learn another free option.

[duncan webster 1Participant @duncanwebster1]

That’s why I’m saving up for Alibre. I got bitten when my 2D CAD suddenly wanted paying for, managed to find another free one that had a very similar interface, but the prospect of learning a new interface was not pleasant.

[JasonBModerator @jasonb]

Well Duncan you will be pleased to know that Alibre needs no knowledge of matrices or transforms as I can use it without knowing about them. Also has a good forum, videos and a reasonable amount of printable info.

[Charles Lamont]

On Charles Lamont Said:

…
Using it requires no knowledge of matrices or transforms, neither Lapalace, nor Fast Fourier nor any other.

No CAD user has to know about matrices, transforms, Laplace, or FFT! Their mention in this thread is an interesting aside, not an Alibre requirement.  Lots of other engineers are into maths.

I’ve no idea if Onshape is easier to learn or not, and being easy to learn isn’t my top priority.   I dumped Fusion360 in favour of SolidEdge even though I liked Fusion and got into it quickly.  Reason: AutoCAD altered the licence!  A problem with cloud products is the vendor can change the deal at any time, and they do.

SolidEdge was harder to learn than F360 but has non-obvious advantages when you get deep into it.

Though I’ve never used Alibre, the interface and functions described in this thread and elsewhere seem straightforward – I think I could switch to Atom 3D without bother, and their licence doesn’t worry me.  Only paying for it!

At the moment, I don’t think there’s an outstandingly easy to learn 3D-CAD package yet.  They all require the user to grip 3D modelling technique and then learn an interface with lots of buttons and nested options.   And beware! Easy to learn often means much simplified, which bites a year later when the ex-beginner needs to do something advanced and finds the tool doesn’t support it.

3D CAD is hard work until mastered, and only then it pays off big time.   No different from learning to drive a car.

Dave

[Andy StopfordParticipant @andystopford50521]

I use OnShape and find it easy to use. The cloud-only aspect is a worry, but if you use Linux your choices are limited – basically OnShape or FreeCAD. If OnShape changes it’s conditions of use then I’ll have to go with FreeCAD, but it suffers from the common open source problems of inconsistent design, over-complicated workflow and patchy documentation (which isn’t to knock the people who develop it, it’s a considerable achievement that it works as well as it does).

There are one or two other Linux CAD programs, but they’re of little practical use. An oddity is SolveSpace which is a pretty basic 3D parametric modeller, but has, almost as an afterthought, quite a capable solver for mechanical design (think designing things with complicated movement requirements, like steam engine valve gears, or robotic arms). It’s a pity they haven’t ditched the modelling aspect and concentrated on that, since I haven’t been able to find any satisfactory equivalent that doesn’t involve spending a lot of money.

[Nigel Graham 2Participant @nigelgraham2]

David –

Thank you for the warning to ask for the appropriate manual: Alibre Atom, not that for the fuller versions!

…..

Not sure how comparing other makes of CAD arrived, nor Linux. Some people have suggested I use Linux but I am not sufficiently au fait with operating-systems for that. More importantly, I don’t want an OS that will not handle  software I already have, written for an MS-Windows base. (Reminds me, I must see if one special, third-party, non-commercial programme has survived rebuilding the system.)

Nor why naming mathematical topics leads to comments that you don’t need them to use a computer. We all know that, and I know base-2^n arithmetic and matrices are part of designing and programming them at depth.  The conversation about maths is really a side one but has raised interesting comparisons of syllabi.

…..

I worry about OneDrive simply because I don’t trust Microsoft, which even if it’s not using your files for some commercial purpose certainly seems to love playing with your photographs at least, and obstructing your attempts to build a cohesive directory system as in, say, WIN-XP. It does these without asking first, informing you what it has done, where it has put things, or explaining itself.

However I will admit I was relieved MS had copied most of my files to its own server so they were not lost when my computer collapsed. It has a solid-state “hard drive” so all applications and data on it are irrecoverable if it fails.

Nevertheless I’d rather have the previous filing system developed since Windows Three days with little change right up to WIN-7, even 10; and so have to rely on my own external drives to archive material. I recall its main changes, improvements at that(!), due to electronics evolution, were the “drag-&-drop” manipulating method, and file names longer than 8 characters.

Incidentally, MS tried putting an extremely basic drawing function in ‘Word’, c.WIN-5. It might have allowed a simple flow-chart, floor-plan or direction-sign, but no more than that. Industry was probably using AutoCAD or equivalent for proper designing.

 

Nothing to stop me simply moving everything to my own drives, of course.

 

 

[Nigel Graham 2Participant @nigelgraham2]

Andy, David –

I have just downloaded that Exercises Manual.

In fact I have used it, some while ago, but at least I’ve saved it along with my Alibre drawings. Useful as a reference to specific tools as well as for its entirety.

[Charles LamontParticipant @charleslamont71117]

I probably should have put a warning that the last sentence (about maths) of my post above was not intended to be taken seriously, and I am also sorry if I have caused the flow of the thread to meander.

I am not keen on storing things in cloud space either, but my 3D modelling work, although representing probably hundreds of hours of play, is not terribly precious.

In spite of the potential disadvantages I still think Onshape provides a good way to dip a toe in 3D water for free. The 3D modelling paradigm is much the same across the range of products, and getting the hang of modelling with one is easily transferable to another. Having some prior experience would help in selecting a product to buy, if the risks involved with a free subscription and public cloud storage were felt to be too great.

[Nigel Graham 2Participant @nigelgraham2]

Oh, if you’ve spent “hundreds of hours” learning then using 3D modelling it’s certainly precious to you!

The so-called “cloud” is presumably Microsoft’s own servers, as much if not more for data-harvesting as a way for users to preserve their own files.

.

Our CAD models are unlikely to interest MS, nor are most of our documents, spreadsheets or other files, unless they reveal enough about us to help the advertising-agencies. The advertisers probably gain more from monitoring our on-line shopping (if we use it) in the very lucrative, general “life-style” areas: clothes, entertainments, home & garden, popular sports, etc.  These agencies also rely heavily on eavesdroppers like Siri and Alexa.

So whilst I am not worried about puzzling MS with my model steam-engine parts, minimal Internet shopping and refusal to use “smart-speakers” and Facebook, consider this:

In the corner of the Windows-11 screen, a small image tells me the weather to save using the real window. This is now an invitation to install so-called “widgets” – I won’t. Previously, it opened Microsoft’s own Bing / MSN, which which copies from the BBC, newspapers and so on. (I wonder if it pays royalties?) Among these links was a photograph of a tree, unrequested, uncredited, untitled… my own, in my back garden. Why?

Further, it revealed a locked MS pick of my and others’ images; all mixed randomly, no filing-system. What for?

 

MS does not ask if you want to use its “cloud”, nor for which files. It assumes all files; working in a way that makes creating a local filing system difficult. Worse, MS’ enforced change from W10 to 11 wiped out my photographs’ filing structure, but not that for other files. It took a long time to repair this attack.

So why Microsoft’s evident interest in my photographs, without consulting me?

Why its interference in my computer?

I cannot see other than trying to find images worth its clients’ use without permission, credit and royalties. Most of our data files are commercially useless to MS, but some of our better photographs of scenery, trees, etc., might be. While the entire anthology can help build patterns useful for direct personal advertising.

….

The real window tells me the weather has stopped raining but is still winding.

Wonder if my workshop will be warm enough for swarf-making?

When still working I examined one CAD make that uses “the cloud” by default, and makes local storage difficult. Light-heartedly, I asked the IT manager if our company would ever use that. He laughed and replied, “Definitely not!”.

 

So while having a safe, remote archive for security, free to us, is fine in principle, we should ask Microsoft’s real purpose? How might it afford to install and operate?

Then ask why reluctance to use Microsoft’s “OneDrive” or “Cloud”.

[Charles LamontParticipant @charleslamont71117]

Nigel you are making assumptions. I don’t know where Onshape stores users’ data. It has to protect the intellectual property of its professional clients, so the data is unlikely to be vulnerable to the undisclosed data harvesting you rightly find objectionable.

“Onshape stores its data not in files on a disk or in a PDM system vault, but in a database. And it doesn’t need to read and write all the data in a document every time it is opened or saved – we have no explicit “save” action at all. Instead, every change is recorded as an increment. As users work, we always write everything they do as they do it, recording only changes, not whole files. We don’t erase or overwrite old data, just add new data. Besides ensuring that you don’t ever lose work when you have a power failure, this is the basis of our unique data management capabilities. We have the basics of PDM built in to our most fundamental data format – every change is recorded, and can be recovered easily. “Saving” versions is trivial: We just add a tag at the appropriate point in history.”

[Nigel Graham 2Participant @nigelgraham2]

OnShape?

I was talking about OneDrive: Microsoft’s own servers, effectively, irrespective of the engineering.

OnShape is the CAD brand that Andy Stopford tells us about, and apparently uses on a Linux system.

I don’t know the ultimate security of anything archived via a Linux-mounted programme, but I don’t entirely trust Microsoft’s business arrangements. Further, its near-monopoly world-wide and the near-universal idea that everything can only be done via the Internet, is a gift to criminals and hostile governments with the expertise to break into anything running on Windows.

I have recently signed up to a medical-research study, and noted that it does use physical paper and letter-post for some of its work – helping keep its records secure.

My former employer its protects itself by putting all its office computers, including those handling the designers’ CAD and analysis files, behind private servers looked after by directly-employed IT specialists.

[Charles LamontParticipant @charleslamont71117]

Nigel, you might like to go back and wizz through again from post #774368 where I foolishly brought this up. I don’t know how or why OneDrive came into the conversation.

OnShape can be run on Linux, Windows, Mac, or iPad. It works in the browser, be that Chrome, Edge, Firefox, Safari or Opera. It is ‘software as a service’. It has nothing to do with Microsoft, and nothing is “archived via a Linux-mounted program”.

[Nigel Graham 2]

On Nigel Graham 2 Said:

 

OnShape is the CAD brand that Andy Stopford tells us about, and apparently uses on a Linux system.

 

No, it doesn’t. It runs in a web browser, and so can be used with any operating system – the files reside on OnShape’s servers (there own, or those whose services they hire), as explained by Charles above.

Edit: Charles beat me to it

[Charles Lamont]

On Charles Lamont Said:

Nigel, you might like to go back and wizz through again from post #774368 where I foolishly brought this up. I don’t know how or why OneDrive came into the conversation.

It’s Nigel’s thread, and, in relation to CAD, he’s explaining why he doesn’t care for the cloud. He’s right to be suspicious!  Whilst ‘cloud’ has plenty of advantages, it is also full of pitfalls.  OneDrive is part of Microsoft’s cloud offering, and it is not neutral.  With cloud, he who sups with the devil should invest in a long spoon, or at least read the Terms and Conditions carefully!

OnShape can be run on Linux, Windows, Mac, or iPad. It works in the browser, be that Chrome, Edge, Firefox, Safari or Opera. It is ‘software as a service’. It has nothing to do with Microsoft, and nothing is “archived via a Linux-mounted program”.

Cloud is good for OnShape because lots of fiddly IT jobs are outsourced and they don’t have to buy servers, or a computer hall, do backups, manage power or secure the installation  Not necessarily good for the customer: he retains the business risk if the cloud service is hacked or breaks.

Can’t be assumed nothing is “archived via a Linux-mounted program”, because the customer doesn’t know how the cloud is implemented.   Which database?  What platform is it running on? How is secured?  Who runs it and in what country(s)?   If any of this matters, watch out!

When this forum migrated, Morton’s depended on 3 or 4 third parties, at least one of whom didn’t to a good job.  When major performance issues were encountered,  I think being on the cloud made them extra difficult to diagnose and fix because the in-house team had to get providers to understand and do the work. Messy!

Cloud is great when it works and nasty when it doesn’t.

Dave

[Nigel Graham 2Participant @nigelgraham2]

Meanwhile…..

Having managed that, with a few false starts and slips on the way, and produced a Drawing version, I can start to work out the details like passages, fixings to the engine case, valves etc.

[JasonBModerator @jasonb]

Looking good

 

One question is this the end that the two covers we have been playing with fit to? If so you have different PCDs on the cylinder but the covers are the same.

[Nigel Graham 2Participant @nigelgraham2]

Thank you!

I wondered if anyone would query those PCDs!

It is for appearance, as the original engine was a prominent, inverted-vertical compound, behind the boiler and between the crew seats.

Advice from various sources including here was that wet steam at only 90psi boiler pressure would not usefully power such an engine in miniature. The boiler has superheater flues but a superheater would create a very long steam circuit from boiler take-off, forwards to the smokebox and back to the engine. So its efficiency is questionable. It would also be very difficult to fit, with very little room for the headers and the flues placed high in comparison with those in a locomotive boiler. On this boiler, the water-level is above the entire barrel.

The engine is also prominent. The cylinders in full-size were between the driver’s and mate’s shoulders. The one photograph I have showing any engine details at all, reveal a single, rectangular block holding the cylinders and valve-chest, (though I’ll use separate chests), with large, separate, D-shaped covers over the cylinders.

So although using a simple-expansion engine I have designed the covers to resemble fairly closely the originals in scale appearance – including different cover and stud-circle diameters.

The covers on the bottom of the block are hidden and can be of equal diameters, and in fact one option I have is to use a single plate extending to the entire rectangle covered by the cylinders and valve-chests, fitted with the glands / guide-bar brackets as I drew, to facilitate holding the cylinder assembly to the engine case, and again to help scale appearance.

 

Juggling diameters to make everything fit and still look “compound” was not easy!

[Nigel Graham 2Participant @nigelgraham2]

A note on OneDrive (Not OneShape, the CAD programme):

It can be “uninstalled”, which I did find surprising.

I have just been dragging all my folders back into some sort of order in MS’ rather confusing default system, including making reserve copies of OneDrive’s collection on an external hard-drive. At the end, after ensuring I’d rescued everything from Seattle, I removed OneDrive.

I’ll put my photograph-albums also on CDs.

The dealer who sold me the drive explained OneDrive is free to a certain capacity – whose value I forget – after which you need pay for it. I don’t know if my files reached anywhere near the limit.

.

I’ve also managed to create section-drawings of that cylinder-block to help me design the various passages.

Of other details, the original engine photograph shows a (valve?) on the back of the HP valve-chest, operated by an oddly-long lever that would have been to the side of the driver’s head. I think it was the starting-valve, the regulator being a globe-valve on the pipe from the boiler.

Having decided to “simplify” the engine it no longer needs a simpling-valve, but we’ve another question.

To drive a miniature steam-wagon you need sit on its platform to reach the controls, so on this model the obvious use for that valve would be as a lever-operated regulator, with the globe-valve kept fully open.

On the other hand, it would be simpler to make that simpling-valve dummy (even omit it!), and drive on the globe-valve – despite its slower operation. The Winson kit, ‘Foden’ look-likes used a screw-action regulator. Perhaps make a globe-valve of ball or plug type, resembling its prominent ancestor but of quick action? Or am I worrying too much there?

If I do fit a superheater it would be sensible to use the faux-SV as regulator, downstream of all that extra plumbing.

Choices, choices…. One way to help me decide is by WAD: Wood Aided Design. Improvise a seat in about the right location and determine where things come to hand. The globe-valve is anyway close to the steering-wheel.

……

“… sitting on the platform…”

On a walk in the sunshine I calculated my scale weight.

The originals’ load ratings were 2 to 3 tons, and (well, so the advertising said) capable of towing a laden trailer as well.

Third-size so multiply 9-stone me by 3^3 = 27 X 1-1/8cwt.

It stretched my mental-arithmetic, which I do practice sometimes, but by chaining times-3, I estimated near the 30-3/8 cwt later given by pen-and paper…

About 1-1/2 Ton.

So I come within the theoretical weight-limit.

 

(What do you mean, those aren’t SI units? No, and E.S. Hindley wagons were not built to ISO either!)

 

This reminded me of seeing a small undertype lorry gamely carting its driver, a bloke quite a bit bigger than me, around a sports field. I think the scale was only 2″, so one-sixth. By the same sums for something whose prototype was probably no more than 10T capacity, and guessing him being of 10st, he was loading the poor little thing, with wheels maybe 3″ diameter, with an equivalent >13 Tons…

Perhaps I was wrong about the scale. Try 3″ scale, i.e. one-quarter. 10st now equates to 4 tons, a realistic figure for the vehicle though the model was so small his figure had to sit side-saddle, legs stretched out to hold his feet above the ground.

 

[Nigel Graham 2Participant @nigelgraham2]

A special drawing: I could not work out how to plot the 4 set of passages between the ports and cylinders more directly on the CAD model.

The two prints (crank-end and cover-end) of the orthographic views of this cut-away give me the foundations for working out just where the angled drillings can go.

To make it more fun, the passage sets all differ in angle. That is because the block is not fully symmetrical, displacing the cylinders slightly towards one end, and the cylinder covers come in three flavours! This results from making the engine top look as if compound. The two sets of ports are the same.

A further effect will be the valve-chests being of different depths, though the cylinder and eccentric-pair centre-lines are symmetrical on the crankshaft.

I didn’t know the Sketch Text tool would work as it does: I took a chance on it. I imagine it would be ideal for preparing 3D-printing or routing files for name-plates etc.  The “engraved” legends read ‘Top O/S’ and ‘Btm O/S’, and strictly speaking should lie along the image’s “vertical” end edges. The image’s upwards-facing surface here is really the unit’s front face.

 

 

[JasonBModerator @jasonb]

I’m not 100% sure if Atom has it but a couple of other options if detailing within a solid item.

1. Go to “Part Colour” and use the slider to alter the opacity and make the part semi-transparent

2. Along the top go to “inspect” then “Precise section” and fill in the box.

 

3. Create a 2D drawing of the part and then create sectional views on that drawing

From the images have you considered just drilling at right angles as your passages are not going to be far off 90deg

drilled at an angle then doing them square will not make a lot of difference to performance.

[David JuppParticipant @davidjupp51506]

Nigel,

You can make 2D sketches in Atom3D whilst a Precise Section View is active – use the precise section view to temporarily cut part in half (say) so you can see the internals whilst working on the sketch for next feature.

Whilst extrude cut of a circle is the obvious way to make a drill hole, there are other options.  Use the line tool to form a thin rectangle half the hole diameter, at the required angle to intersect other passages – then revolve cut it around one of its long sides.  This can avoid having to add angled planes to drill from.

Remember than you can go back and edit sketches & features – nothing wrong with placing something roughly in place, look at the result, go back and adjust until it is satisfactory.  Equally if cutting hole from an angled plane – you can alter the angle for the plane to adjust the path of the hole.

Unlike in the workshop, in CAD a part isn’t scrap because of a badly placed hole – adjust or delete the hole.

[Nigel Graham 2Participant @nigelgraham2]

Thankyou Jason and David.

The most critical area is the top, off-side end, because the cylinders are biased by 1/4″ to that end and it has the smallest-diameter cover (the “HP” cylinder), leaving not much iron to drill holes through.

Using passages parallel to the surface would certainly be the easiest, and I was counting on 4-off 3/16 or 5mm diameter passages per port. I obtained the port dimensions from Martin Evans’ book, but could not find any definite information on passage sizes.

Making them too small throttles the steam in both directions and creates too much exhaust back pressure: after all the full port area = 0.187 sq. in. but 4 X 3/16 dia passages gives only 0.11 sq.in., less than half.  Too large creates too much clearance volume, wasting steam, though I don’t know how critical this is in a miniature engine.

I have the drawings for the Maid of Kent loco, which I think has cylinders of roughly similar bore and stroke, and I am adapting K.N. Harris’ valve-gear for this. So I will examine that as an example.

There is another option, since I’ve not yet cut any metal beyond turning the top covers’ blanks, only I’ve mislaid my one-and-only photograph that lets me verify such details, is to use 5-stud patterns. The maximum possible load on each 1/4″ BSW stud would be only 32 lbs. for most of them, and less than 64 for the shared single one.

The outer passages can be set to enter the end walls of their ports, giving more room for the inner pair to avoid that stud hole. I can also deepen the ports a bit. I’d like a minimum of 1/8″ metal left between any holes anywhere, but am not sure yet if that’s feasible.

 

Easy in large scales and full-size: the passages are of the same cross-sections as the ports, and can be cast in so leaving oodles of end wall for studs!

[Neil WyattModerator @neilwyatt]

I’ve been doing a lot of work in Alibre over the last couple of years. Chiefly modelling tanks, planes and missiles up to 1945.

My current project as of last week, a JU 287 in 1:72 scale (as are the various missiles scattered about). Some unusual techniques here:

[Author]

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