[HELP] Generic Building Help Topic

[howitzer]

2 minutes ago, ozacek said:

There's something about which I can't quite make up my mind, and I was wondering if others have an opinion. In a case like this, where a lot of torque goes through (like lifting up a heavy vehicle), is there a preferable approach?
 

In the top setup, the axle has better support, but it's weaker because it's 9L long. In the bottom setup, it's the opposite. 
Also, if you think the top setup is better, would that still be the case if the axle had to be 11L ?

Thanks!

The top one is definitely stronger, as it has more support as you said. The added length doesn't make it weaker either, as the distances of the gears are equal - the extra length at the ends wouldn't matter at all if there were no support from the bracket, but as there is, it makes it stronger. Support could also be added to the center for even stronger transmission, though it has to be firmly anchored to the structure around the gearing.

[ozacek]

8 minutes ago, howitzer said:

The top one is definitely stronger, as it has more support as you said. The added length doesn't make it weaker either, as the distances of the gears are equal - the extra length at the ends wouldn't matter at all if there were no support from the bracket, but as there is, it makes it stronger. Support could also be added to the center for even stronger transmission, though it has to be firmly anchored to the structure around the gearing.

Thank you for the insight. Though by weaker, I meant that it's more prone to twisting under high torque. It's much easier to twist an 11L axle than a 5L one.

Edit: I see what you mean, the twisting only applies over the length between where the gears transmit the torque, which is indeed the same. I hadn't thought about it this way - thanks!

Edited April 9, 2022 by ozacek

[ozacek]

Then still about axle twisting, if I need to transmit high torque over a fairly long distance, say 16L, one 16L axle or two 8L is probably not the best choice, but it there some rule of thumb? Should I go all the way down to 2L and just have a series or axle connectors, or something in-between?

Thank you.

[Jayden]

25 minutes ago, ozacek said:

Then still about axle twisting, if I need to transmit high torque over a fairly long distance, say 16L, one 16L axle or two 8L is probably not the best choice, but it there some rule of thumb? Should I go all the way down to 2L and just have a series or axle connectors, or something in-between?

Thank you.

I use four or five long axles with axle connectors and that usually works fine.

[Carsten Svendsen]

Do a test and connect 2l axles in connectors/joiners vs a 10L axle. the axle on its own is twisting less than the connected axle

[howitzer]

8 hours ago, ozacek said:

Then still about axle twisting, if I need to transmit high torque over a fairly long distance, say 16L, one 16L axle or two 8L is probably not the best choice, but it there some rule of thumb? Should I go all the way down to 2L and just have a series or axle connectors, or something in-between?

Thank you.

If you need a really high torque over a long distance, there are many ways to make an axle that's stronger. You can reinforce the axle with bushings, or make a series of 2L axles and connectors like you said. Or you can stack multiple 3941 along the axle. Or make a beam of 2 bricks side by side, sandwiched between plates and with 1x2 bricks with axleholes at the ends. There was a demonstration of these by Akiyuki:

 

[ozacek]

5 hours ago, howitzer said:

You can reinforce the axle with bushings

That's a really good idea, I like that! It's clean, simple, and certainly enough for my needs.

[Erik Leppen]

Or you gear up before the long axle, and gear down afterwards. Then the twisting has less of an effect, because it's geared down afterwards. On the flipside, there will be a bit more friction.

[efferman]

On 4/19/2022 at 7:05 PM, Erik Leppen said:

Or you gear up before the long axle, and gear down afterwards.

this eats a lot of torque in complete. I tried the up and down on my rotator to make it easier for the universal joints and had a massive power loss.

[ozacek]

10 minutes ago, efferman said:

this eats a lot of torque in complete. I tried the up and down on my rotator to make it easier for the universal joints and had a massive power loss.

I was suspecting something like that, but I'm surprised it's 'massive'. Do you think it comes from just having more gears, or from something else?

[efferman]

8 hours ago, ozacek said:

or from something else?

The gearcount was more or less the same, so i think the physics behind the up and down was the reason for the loss.

[thekoRngear]

Umm... this is a bit embarrassing for someone who been regularly building Big to mid-size Technic sets for couple a years and now face difficulty when building certain similar aspect of building 90's little sets. I face slight difficulties moving my 8225 Rally Cart and 8838 Shock Cycle.

The problems are similar: the engines. They create some kind of blockage/friction when moving. I checked parts and build process. They seem fine. I disconnected the engine and they run smoothly. The reason I think causing this trouble is this: the #2853 Engine crankshaft is not having sufficient slack when rotating the pistons. (pardon my limited choice of words)To elaborate this: when the crankshaft rotates at one point it needs to get slightly out of the hole of whatever beam (or part) it is connected and moving from. For 8225 and 8838 I see there is literally not this tiny amount of space that could provide that slack for the crankshafts. They are perfectly tight. Howevr, I should also add I'd built both of them in my childhood. They used to move so smoothly (or maybe I was not aware of it this much).

Any suggestion guys?

[Carsten Svendsen]

On 4/21/2022 at 8:08 PM, thekoRngear said:

Umm... this is a bit embarrassing for someone who been regularly building Big to mid-size Technic sets for couple a years and now face difficulty when building certain similar aspect of building 90's little sets. I face slight difficulties moving my 8225 Rally Cart and 8838 Shock Cycle.

The problems are similar: the engines. They create some kind of blockage/friction when moving. I checked parts and build process. They seem fine. I disconnected the engine and they run smoothly. The reason I think causing this trouble is this: the #2853 Engine crankshaft is not having sufficient slack when rotating the pistons. (pardon my limited choice of words)To elaborate this: when the crankshaft rotates at one point it needs to get slightly out of the hole of whatever beam (or part) it is connected and moving from. For 8225 and 8838 I see there is literally not this tiny amount of space that could provide that slack for the crankshafts. They are perfectly tight. Howevr, I should also add I'd built both of them in my childhood. They used to move so smoothly (or maybe I was not aware of it this much).

Any suggestion guys?

Have you tried installing a plate to raise the clearance between crank axle and engine block?

[Andman]

.

Edited April 23, 2022 by Andman
Didn't refresh page and thus didn't see the replays.

[thekoRngear]

12 hours ago, Carsten Svendsen said:

Have you tried installing a plate to raise the clearance between crank axle and engine block?

Happy to say it is fixed. For the 8225 I loosened the half bushes of the rear driving axle so that the studded beams can ever so slightly be wide. It allows the engine crankshaft rotate freely. The cart now moves smoothly.

For the shock cycle, I loosened the half bushing (those were bit tight when I built them) that holds the 16z and 24z gears in the 6L axle. Also, the bevel gear that comes out from one of the crankshafts was mounted with more gap between the engine frame and the gear.

There indeed are Technics within (specially the old) Technic 

Thanks for response

Edited April 24, 2022 by thekoRngear

[Carsten Svendsen]

18 hours ago, thekoRngear said:

Happy to say it is fixed. For the 8225 I loosened the half bushes of the rear driving axle so that the studded beams can ever so slightly be wide. It allows the engine crankshaft rotate freely. The cart now moves smoothly.

For the shock cycle, I loosened the half bushing (those were bit tight when I built them) that holds the 16z and 24z gears in the 6L axle. Also, the bevel gear that comes out from one of the crankshafts was mounted with more gap between the engine frame and the gear.

There indeed are Technics within (specially the old) Technic 

Thanks for response

Wow, I can't believe this. This is basically the one thing that's pounded into your face in every instruction

[thekoRngear]

13 hours ago, Carsten Svendsen said:

Wow, I can't believe this. This is basically the one thing that's pounded into your face in every instruction

LOL. No, I was aware of the warning found in the olden days instructions booklets. The rear axle was made sure to have the bushing got sufficient spacing in between the half-bush and the studded beam on each side. As I've said in the previous post I even disconnected the axle that has the 16z gear on one side and the crankshaft on the other. The rear axle moved absolutely fine. Thing is crankshaft's cross-axle part needed a slightly more space when rotating. The right studded beam could not provide that. So, further more spacing in between half-bushes and the studded beams on each side and it is completely gone.

Same cannot be said for the 8838 Shock Cycle. It is a technical marvel. I have had hard time when building it for the first time when I was 8/9 and now I have a great experience at 36 (with some err...initial quirks). It's amazing to see how Lego used to make-do's in the early 90's (and even earlier) when the essential parts were not even released. The housing that the Shock Cycle got actually cannot be freed from the crankshaft's rotating slack demands I think. The housing is secured/cemented by top and bottom brick placement. Hence, loosening the gear even further and also loosened just a little bit in between the 3L black clutch pins and the engine blocks. But I forgot to make sufficient space in between the bushes that hold the 16z and 24z gear bearing axle  So, blockage and friction made it noisier and worse. Made proper spacing and the unnecessary friction was gone. The crankshaft's slack demanding blockage is still here but it is acceptable.

Edited April 25, 2022 by thekoRngear

[ukbajadave]

Am I going about this the best way? I want a constant input on the red axle in one direction and the yellow output to change direction with the switchover catch. I just can't figure out the right gears to connect the left driving ring to the left grey 16z gear. It needs an even number of extra gears and I want the ratio in both directions equal. I don't have any 28z gears but I do have 20z clutch gears. Any help or alternative methods appreciated 

[Jundis]

Just add three 8 tooth gears in between:

[ukbajadave]

4 minutes ago, Jundis said:

Just add three 8 tooth gears in between:

So simple!!! Thanks very much for that 

[Technic tango]

does anyone know where I can look for a steered tandem bogey suspension with the servo on the bogey and Tatra suspension on the tips? I cant put the steering back through the turntable due to space limitations. here is a screenshot to see a bit better what I have already and what I mean:

 

On 3/21/2022 at 10:36 AM, technicfanatic said:

Hi Everyone, I'm aware of 32054 to attach an axle and give it friction. 

Is there anything that can be added to the middle of an axle to add friction? I have a structure with an axle I want to add friction to, but in order to use 32054 I would have to modify the structure in a way that annoys me. It would be much more convenient to be able to add something in a pinhole in a link arm the axle is going through.

Thanks!

you could stuff 2 gears inside a wider smaller tire then it becomes a pretty resistant linear clutch

Edited May 6, 2022 by Technic tango
added picture

[Jurss]

10 minutes ago, Technic tango said:

ts not posting my image

post link to some picture hosting - bricksafe.com, flickr , eurobricks doesn't host pictures (just something small for avatar)

[Technic tango]

8 minutes ago, Jurss said:

post link to some picture hosting - bricksafe.com, flickr , eurobricks doesn't host pictures (just something small for avatar)

i linked a picture but its not coming up as a preview like the others 

edit: I figured it out

Edited May 6, 2022 by Technic tango

[Hrafn]

@Technic tango how were you planning on steering that swing axle bogie module? Can you use skid steering on it?

[Technic tango]

1 hour ago, Hrafn said:

@Technic tango how were you planning on steering that swing axle bogie module? Can you use skid steering on it?

I had the idea to make pivots after the black u frames. If I steered the entire bogie then it would drag the tires a lot and take up a lot of space when turned