[HELP] Generic Building Help Topic

[CrankyCraig]

1 hour ago, agrof said:

For engine build, and for particular small assemblies I use rather LDD, and then import it into Stud.io. Unfortunately the snap constrains are not very good in latter, but it has the potential. There is no need to fuzzle to build a V8 engine (as example), once somebody did it already. Just take an LDD official model with the required assembly (V8 fake engine as example, included in 42039), undress it by deleting unnecessary parts, save, and import it into Stud.io model.

I don't see exactly where and how you would like to connect those arms, but maybe an idea to use sub-assemblies, which can be rotated separately. Might be that it will ruin a model though, due to overconstraining.

Ah, Agrof, just the fellow. I'll attempt to stay on topic and save the gushing over this model for your thread - mostly at least, obviously I'm a big fan.

Copying a pre-built engine from somewhere else is a great idea. It's these tricks of the trade I need to learn.

Here's perhaps a better attempt to show what I was hoping to achieve:

There's a correct set of angles there somewhere, but obviously, I haven't quite found them yet. I don't know what you mean by 'overconstraining', but everything is sub-modelled, so manipulation is easy enough, it's just that it's still much faffier than building with bricks. Perhaps I've just reached it's limitation, but I'm still hoping I'm making a meal of this just because I don't truly know what I'm doing yet, and appreciate I haven't picked the most straightforward model to begin my endeavour. I was enjoying learning until I reached this point.

As previously stated, this is my first foray into the world of digital design. Is there perhaps another program better suited to this?

Edited May 15, 2020 by CrankyCraig

[agrof]

1 hour ago, CrankyCraig said:

There's a correct set of angles there somewhere, but obviously, I haven't quite found them yet. I don't know what you mean by 'overconstraining', but everything is sub-modelled, so manipulation is easy enough, it's just that it's still much faffier than building with bricks. Perhaps I've just reached it's limitation, but I'm still hoping I'm making a meal of this just because I don't truly know what I'm doing yet, and appreciate I haven't picked the most straightforward model to begin my endeavour. I was enjoying learning until I reached this point.

As previously stated, this is my first foray into the world of digital design. Is there perhaps another program better suited to this?

Overconstraining is coming from CAD modelling, I don't really want to go in depth here. There are other CAD softwares out there for LEGO building, unfortunately I can not comment on those, for my purposes (brainstorming and documenting) LDD and Stud.io are fine. I struggle with the same alignment issues sometimes too, and honestly sometimes I just leave as it is, rather than start to build everything again from scratch. Especially for such angled items, where reality proves the buildability (like simple suspension arm positions angled with springs into correct positions). Not eye pleasing, but saves some nerves. 

You might know this, but just to be sure, I share. There is a way to set manually the angles very-very precisely. You select the part / assembly to adjust - select rotation - select rotation point. Once the blue bi-headed arrow appers, hover with the cursor on it - it will turn reddish. Left click once on it.

Then the rotation plane tool appears, but now you can go directly into the value cell with the cursor, and enter exact values (example here: 180.23 degrees). Important to use dot instead of dash!

I hope this helps, a lot of trial and error, but in the end it can be set perfectly.

Edited May 15, 2020 by agrof

[CrankyCraig]

I did know how to set the angle manually, but thanks all the same. It's what made stop, thinking about how small the tollerances are in Stud.io, and how many different permutations each of those finely editable orientations creates. Just knowing it's a program limitation is really useful though, and not just something I'm not doing. It's a shame, because I could see some enormous benefits in designing digitally, but having dabbled with it a bit, it seems there are some big negatives too.

As difficult as it'll be for my OCD then, I'll leave it like that and carry on. I can already pre-empt what would happen next; I'd find a set of angles Stud.io was happy with, only to have to go through it all again when I added in the 9.5L shock absorber. I'd then turn green and muscular, and start breaking things.

It's hard to believe the only way to do it is trial and error, and there's no way to relax hinges and manipulate the ends of pieces in a drag/drop way or to force a connection within a tolerance, but perhaps we'll see those things in a future update. 

Thanks for all your help, it's very much appreciated. I'll get a post on your Class 1 thread as soon as I have something meaningful to contribute. 

[agrof]

17 minutes ago, CrankyCraig said:

As difficult as it'll be for my OCD then, I'll leave it like that and carry on. I can already pre-empt what would happen next; I'd find a set of angles Stud.io was happy with, only to have to go through it all again when I added in the 9.5L shock absorber. I'd then turn green and muscular, and start breaking things.

Might your avatar picture is your destiny...  Be prepared, just saying...

Feel free to create your own [MOD/MOC] topic, it deserves to be presented under your name. 

[Rudivdk]

5 hours ago, CrankyCraig said:

It's hard to believe the only way to do it is trial and error, and there's no way to relax hinges and manipulate the ends of pieces in a drag/drop way or to force a connection within a tolerance, but perhaps we'll see those things in a future update. 

Well, I have been using LDCad (created by Roland Melkert) for quite a while now and I am pretty pleased by the possibilities it gives for (manually) manipulating rotation points and angling parts and sub assemblies.

Here is a Youtube vid made by Roland himself showing how to easily make angled connections (triangle) starting with straight placed elements (square).

I think I have also seen a vid where some sort of object snap was used to achieve this, but can't find it, maybe @roland knows?

Check his other vids on LDCad as well, good tutorials. No idea though if this functionality is available in other LEGO CAD programs. You could try posting your question in the LEGO Digital Designer and other digital tools forum to check on that, there are some real expert active over there, including some of the actual program designers.

Edited May 15, 2020 by Rudivdk

[CrankyCraig]

41 minutes ago, Rudivdk said:

Well, I have been using LDCad (created by Roland Melkert) for quite a while now and I am pretty pleased by the possibilities it gives for (manually) manipulating rotation points and angling parts and sub assemblies.

Here is a Youtube vid made by Roland himself showing how to easily make angled connections (triangle) starting with straight placed elements (square).

I think I have also seen a vid where some sort of object snap was used to achieve this, but can't find it, maybe @roland knows?

Check his other vids on LDCad as well, good tutorials. No idea though if this functionality is available in other LEGO CAD programs. You could try posting your question in the LEGO Digital Designer and other digital tools forum to check on that, there are some real expert active over there, including some of the actual program designers.

Having never used LDD and with no sound, it's tricky to follow the process in those videos, but I'll give them a watch and try to gauge a feel for what's going on. Once the video you suggested finished, I noticed this in the thumbnails, which is something similar we'd discussed earlier:

I don't know what magic was performed at 18 seconds, but if it's that easy I need to explore LDD! I suspect it was just a Macro though.

In all honesty, I've no right to think it should be easy to manipulate an object freely - I know so little about programming, I can't even program my homes thermostat - but it just seemed to me like the kinda thing you'd be able to do in a digital program 

I did try posting a different question in that section, but it doesn't seem to be one of the more active area's of Eurobricks. You're right though, that question may be better placed there.

[Rudivdk]

26 minutes ago, CrankyCraig said:

 LDD

Maybe just a typo on your end, but the vids are from LDCad. Different program, wouldn't want you downloading the wrong one... EDIT: You can get it here by the way: http://www.melkert.net/LDCad, under the 'download' page.

26 minutes ago, CrankyCraig said:

I suspect it was just a Macro though.

Within LDCad there are a number of predefined scripts available (Roland will sometimes add a new one with new releases), which in this case perfectly aligns piston parts if they are placed in the correct starting position relative to the cylinders. So you still have to build the cylinders at their correct angle, put the crankshaft in with all the pistons, piston rods etc, but then the angle is set perfectly by the script. As far as piston placement goes: yes, it's that easy .

26 minutes ago, CrankyCraig said:

but it just seemed to me like the kinda thing you'd be able to do in a digital program

Same here, I would think that using an objects snap points would make it possible to do what you asked. But I am no programmer either... LDCad has the closest thing I could find in any LEGO CAD program.

26 minutes ago, CrankyCraig said:

You're right though, that question may be better placed there.

I wasn't modding on you, just thought you would get better answers over there. But apparently there is less activity in the digital forum than I expected...

Edited May 15, 2020 by Rudivdk
added the URL for downloading

[roland]

22 hours ago, Rudivdk said:

I think I have also seen a vid where some sort of object snap was used to achieve this, but can't find it, maybe @roland knows?

The technic engine script loops trough all rod and engine block parts and calculates the correct rod angle assumed it is already at the correct location (e.g. snapped to the crank axle).

It will also position/orient the piston part and will add one it there aren't enough of them in the model.

As assumed this is a macro located in the scrips/technic menu.

In the latest version there is also a macro to position universal joint elements based on a collection of guidance points and a correctly orientated starting part.

As these macro's are scripts you can add things yourself and I'm also open to suggestions for things to add in the next version (or you could do a manual installation of new scripts if you don't want to wait).

As for snapping...

LDCad only supports basic part snapping, which is disabled by default, as I didn't want to have the 'fight the system' problem you seem to have above :)

Snapping can be enabled using shift+p or clicking the red GS label in the bottom left corner of the compass  (it changes to PS).

While snapping is enabled the normal grid tools are still available too, so if nothing nearby snaps you can still use grid placement.

 

 

[ukbajadave]

Opinions required please. I'm trying to make a fast(ish) car using only PF, no Buwizz or sbrick. Is there any advantage to coupling motors like this rather than hard coupling with 24z gears?

Also, am I simply barking up the wrong tree with 2 L motors and gearing up? Will there be enough torque to actually move stuff?

[Jurss]

If You are going for speed, then that differentilal is not needed, create hard coupling. 

If there will be enough torque - depends on vehicle weight.

[Touc4nx]

In my experience, the differences in rpm between two motors is hardly noticeable...
And if you have to use a lot of torque, then hard coupling is better ( and avoid bevel gears in angle)

[ukbajadave]

4 minutes ago, Jurss said:

If You are going for speed, then that differentilal is not needed, create hard coupling. 

If there will be enough torque - depends on vehicle weight.

 

1 minute ago, Touc4nx said:

In my experience, the differences in rpm between two motors is hardly noticeable...
And if you have to use a lot of torque, then hard coupling is better ( and avoid bevel gears in angle)

Thanks, that will make it simpler 

This all started when I tried to motorise 42077 B model. Nice and easy to swap the fake motor for a L or XL but it barely moved after I geared it up loads. So then I stripped it down to a chassis and it was only a little better. Now I've started from scratch with 2 L motors and it is still sloooow. I'm going to look foolish if it's just flat batteries...

[Touc4nx]

If you want to stay with your idea to swap the fake engine by a motor, then just exchange the gears linking the fake engine and the differential. 
And batteries are drained considerably fast if you use two L motors. 

[JLiu15]

Hey guys, not sure if this is the right place to post this (this is the most suitable thread I found).

I've been building Lego Technic for years, but I've always felt like I'm out of the loop on key Lego Technic terminology. For instance, the definition of a 'pendular suspension'. A google search brings up pretty much exclusively Lego pendular suspensions. I've heard other definitions for this type of suspension such as solid axle or oscillating axle, but I've never seen the term 'pendular suspension' applied outside Lego suspensions. 

Another such definition is the subtractor. A google search for 'subtractor tank' brings up only Lego subtractor tanks. Like with pendular suspensions, I don't think I've ever seen the term 'subtractor' being applied to such a mechanism outside Lego Technic.

My question is, did these terms just spontaneously arise within the Lego Technic community? It's baffled me ever since I started building Lego Technic, because I feel that I should have seen this terminology used outside Lego Technic by now, but I haven't.

Edited June 6, 2020 by JLiu15

[AMX]

As for “pendular suspension” I don’t really know 

but the subtractor is used in real life but it is called “tank steering system/differential steering/double differential steering”

[JLiu15]

12 hours ago, AMX said:

As for “pendular suspension” I don’t really know 

but the subtractor is used in real life but it is called “tank steering system/differential steering/double differential steering”

Hmm, I wonder how the term "subtractor" in this context surfaced then. I used to think that these terms in their respective context were more widely used in Europe (like a regional English dialect) as it appeared to me that most Lego Technic AFOLs are from Europe, but I doubt that's the case (I live in the US).

Speaking of which, it also seems that the term "mudguard" as used within the Lego Technic community usually refers to the wheel well. For instance, the Bricklink listing for part 46882 (Land Rover wheel arch panel) refers to it as a 'mudguard', but Google image results for 'mudguard' seem to suggest otherwise (it's a piece behind the wheel, not the wheel well itself).

[pleegwat]

The term subtractor as used in lego reminds me of this video (specificall from 12:35):

 

[JLiu15]

1 hour ago, pleegwat said:

The term subtractor as used in lego reminds me of this video (specificall from 12:35):

Interesting, this kinda explains how terms like "adder" and "subtractor" in the context of Lego Technic originated. Thanks for sharing.

[Leo12]

Can anyone explain how this gearbox works to me? I understand what happens when the driving ring is engaged, but I don’t get why the differentials output doesn’t spin freely when the driving ring is disengaged.

Gearbox Video

[aeh5040]

6 hours ago, Leo12 said:

Can anyone explain how this gearbox works to me? I understand what happens when the driving ring is engaged, but I don’t get why the differentials output doesn’t spin freely when the driving ring is disengaged.

Gearbox Video

It looks as if it should to me, too.  Are you sure it doesn't?

[Leo12]

3 hours ago, aeh5040 said:

It looks as if it should to me, too.  Are you sure it doesn't?

Yes, it must because it’s a three speed. I even made a similar one and it worked. The description mentions something about applying an radial force to the axle to stop it from rotating when torque is applied to the output , but I don’t know how that is achieved.

Edited June 16, 2020 by Leo12

[aeh5040]

Right, I couldn't understand that, either.  Are you sure it is not just operating under friction in the middle speed?  If you try to stop the output turning with your fingers does it stall the motor?  Seems like I need to try it too....!

Edited June 16, 2020 by aeh5040

[Leo12]

Hi everyone, I’m wondering if there are any alternatives to worm gears. I need something that can only be driven one way, but I don’t want the extreme reduction provided by the worm gear. Do you have any ideas?

[doug72]

GBC train reversers use an extra gear with a ratchet arm to ensure that main gear can only rotates in one direction

[Leo12]

5 hours ago, Doug72 said:

GBC train reversers use an extra gear with a ratchet arm to ensure that main gear can only rotates in one direction

It’s not that I want it to rotate in one direction, I just want to make sure that the output can’t drive the input.