Inserting An Angled Feature (Alibre Atom)

[JasonBModerator @jasonb]

I suppose it was not obvious to David and me, as like a lot of users we run with the sketches visible all the time so we take it for granted that others are doing the same and therefore don’t mention it as part of an explanation of “how to”

Another advantage of having the sketches visible is that it makes it easy to select one that may need editing. Rather than searching down a long list on the left hand explorer list if you have not named each one all you do is right click the red sketch and select edit, etc.

[David JuppParticipant @davidjupp51506]

The sketch highlighted blue, because it had been selected as the profile to revolve (presumably was auto selected as the sketch done immediately prior to openign the revolve tool, or was chosen from the Design Explorer).

The Toggle Sketches makes all sketches visible in the workspace (and hence selectable, e.g. in the revolve tool).  In a more complex design it can be distracting to have many sketches visible – hence the ability to turn off their visibility.

[David Jupp]

On David Jupp Said:

The sketch highlighted blue, because it had been selected as the profile to revolve (presumably was auto selected as the sketch done immediately prior to opennig the revolve tool, or was chosen from the Design Explorer).

Even if the last item sketched the blue sketch disappears when you click the revolve tool if sketches are not visible. So needs selecting to make the blue one visible. It still puts the Sketch No into the “sketch to be revolved” box if it were the last item on the list but you can’t see anything.

Might be something to look at for a future update, if the sketch No or name is in the box then have Alibre automatically make that sketch clickable.

[Nick HughesParticipant @nickhughes97026]

Apologies for the delay replying, still working for a living turning handles, with no internet access allowed to us plebs on the shop floor (No phones either due to “Security”)!

Thank you David and Jason, Sketch Visibility was indeed off. I don’t recall deselecting this in versions prior to V29, as I’ve not had any issues previously, but hay ho onwards and upwards.

[Nigel Graham 2Participant @nigelgraham2]

Jason –

It was that disappearing trick that was driving me up the wall.

I’ve just used some of my smaller drawings to examine these toggle tools more closely – and to try to work out how I created one or two of the models.

Then took this one and nearly improved it. It’s not intended as a part design but is among several created as system diagram elements; this one representing a change-over valve. The inclined passage (the switch itself) is a bit mis-matched because I could not quite visualise the result, but at least it’s the right shape. A sweep might be tidier.

Incidentally this symbolic valve and its companions are intended for documenting vacuum-brake work I am installing on my club’s loco driving-truck. The system is not quite as straightforwards as first seemed.

[JasonBModerator @jasonb]

A sweep would give a tidier junction where the diagonal hole meets the one sfrom the ends.

Good job it is only symbolic otherwise I would be asking how you drill the diagonal hole. 😁

But good to see you have got the hang of it and its another tool you can use, just don’t leave it too long between sessions and forget how it works. Good tool for the drilled steam passages in a cylinder block.

I’ve just had a part 3D metal printed that has a long snaking air/steam passage that was created using a swept cut that you would have had difficulty casting using a core a sit is only 2mm dia.

 

[Nigel Graham 2Participant @nigelgraham2]

Thank you!

If I was to make that valve physically, without 3D printing I’d have to drill the diagonal passage from the side of the block then plug the opening. An old technique, and I think a lot of the older miniature engine designs simplify it further by making all the passages at right-angles, although that reduces the efficiency in steam and i.c. engines.

The other way of course is to make the block in halves rather like the illustration, but this introduces the problem of making a reliably leak-proof joint over a large area.

It is too easy to draw something that is too difficult to make as drawn, whether draughted manually or by CAD…

[Nigel Graham 2Participant @nigelgraham2]

I’ve had another go at drawing the entire injector body, on the strength of the above.

I must admit I am very impressed by D.A.G. Brown’s ability to fabricate these things to his design: the overflow channel is a tiny piece of brass tube with a slot along its length, and its upper port a needlessly awkward “oval” .

I worked from an enlarged photocopy of the page in the book, as the original drawings are very small and hard to read in places.

As well as an Alibre exercise this investigates a slightly less elegant version potentially easier to make (should the Muse take me). The sloping overflow conduit is now machined from thick brass plate, and the port is an ordinary drilled hole of similar cross-sectional area. It’s all still five bits of brass soldered together but it may be feasible to make the complete overflow body in one piece.

The “threads” are not helices; just patterns of an annular groove prettified with tiny fillets. They are though, very close in scale to the specified 5/16″ X 32TPI thread. Eventually I twigged using the Mirror tool and an auxiliary plane to copy them from one end to the other, to save plotting them again. (I decided to omit the internal threads in the overflow outlet and valve body, for now anyway.)

I’ve not yet drawn the screwed cap. The original drawing is difficult to interpret and like the rest of the set, a mix of binary and vulgar fractions. (As were my words, at times.) Nor the cones I would expect would “simply” be rotary extrusions.

 

I still find it hard to choose the most appropriate plane for starting the part sketches, making the assembly stages a lot more awkward, which is why they all upside down here.

 

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