my big excavator

[Alasdair Ryan]

this thing is doing my head in

there are about .....to many flaws to count

the pump switches dont work properly as the video will show

air making is not ok but am sure it could be better

slew is not reinforced so the upper thing sags

extremely heavy on battery's

to heavy to drive

and its a costly build and i have not finished it yet

you can add your some if you like

on the other side i do have more lego now if i was to scrap it

[Milan]

Ok I cant say you to continue work on it, or disband it, but I can give you some advices,comparing your moc to my big JCB excavator.

First of all as I told you a while ago, pneumatic cylinders wont work very well for such a big MOC - use brick built cylinders or LAs

Slewing is to fast, reduce it a little bit, it will result in less swinging of the arm.

Drive has to be tested in advance, in a very start of the building by putting some weight (2-3 kg) on undercarriage...books are good. It is best to use XLs directly on sprocket wheels in reduction 5 to 1.

Sagging of the upper part is the result of not having some kind of support - make roller bearings around the turntable. Or at least just ring of tiles and one wheel at the point where the sagging is greatest.

[Alasdair Ryan]

it is sad that i got this far and that nothing seams to work i will start work on a new excavator soon with progress for ya all to see

[Milan]

it is sad that i got this far and that nothing seams to work i will start work on a new excavator soon with progress for ya all to see

Nothing seems to work because you haven't put enough effort in it at the first phase of the design process.

That is essential on these big projects, and one of the reason why they can be built for months.

[Tobbe Arnesson]

Learn from the mistakes, tear it apart and try again. Big great models go through a lot of iterations, it's never made in one go.

Rather than trying to build it all in one go to identify what functions you want and make that into a list. Then turn that list into sub models, in your case it would be something like:

Under carriage

Super structure

Digger arm

Then identify what would be needed in turns of strength etc. and make sure every part is up to it.

Personally I nowadays tend to make prototypes before I go for the real deal. I often do the prototypes in colors I'm not planning to use in the main model since I don't own enough bricks (does anyone?), just make sure the parts used in prototyping do exist in the color you plan to use in the final model...

Don't be afraid to fail! Just make sure you learn something from it so your next try will be better. Take a look at how Sariel's tanks have evolved over the years: http://www.eurobricks.com/forum/index.php?showtopic=48004

[Alasdair Ryan]

Nothing seems to work because you haven't put enough effort in it at the first phase of the design process.

that is not true i whave been working on it for at lest a year

[Alasdair Ryan]

has any one got any ideas for lego for home made actuators believe it or not their are not much on brick shelf i could look at if there are any good pics on any that would be a great help

[Milan]

has any one got any ideas for lego for home made actuators believe it or not their are not much on brick shelf i could look at if there are any good pics on any that would be a great help

Why don't you try to make your own design?

It could result in even better mechanical cylinder than anything existing.

I made my own for my machine, and I am very satisfied.

If you don't want to bother, you could use swissbager mechanical cylinder, they are wide, but they work.

[allanp]

I would start again from scratch, but DON'T DITCH THE PNEUMATICS. I have built more than one excavator of a similar size and the pneumatics move at a realistic speed and with plenty enough power to dig a nice hole in my garden. I did try using LAs but, well, it was slow and boring and weak (even with motors directly attached) and too unrealistic for my liking.

Anywho, first of all, concentrate on building your compressor. I notice you have one XL motor powering about 8 pumps!!! From those parts you can get all the power you'll ever need. However you should off-set the pumps so that they are not all going in and out at the same time, like the pistons in an engine, they are offset for smoother operation. This will give you a much more constant air flow and make life much much easier for the motor. This method gives me masses of power from even quite low batteries. The biggest one i've built also had 8 pumps powered by one XL motor. it was about 4 studs wide, 9 studs long and about 7 studs high plus the motor, so it should fit in fairly easily, oh and make sure your hoses have no kinks in them. Personally, I don't like powering my switches remotely as I like the precise control of operating the switches manually, however if you must make them RC, I would suggest coming up with a different method of controlling them as the ones that have shown up here around eurobricks draw alot of power just to keep them switched on. This wasted power means there is less power going to your compressor motor. Fear not, there are other ways of controlling your switches remotely, but i'm not gonna take the fun out of the challenge by telling you, . If this model is only for show then you don't need to re-inforce the turn table, just position the motors and batteries inside the superstucture so that it is balanced. However it would be a shame to waste all that power the pneumatics can give you. So if you want to do some actual digging in the garden (which is more fun when the neighbours aren't watching ) then you might want to re-enforce it. four wheels on the underside of the superstucture running on a smooth surface below works quite nicely. The rest is all down to trial and error. But keep at it, trust me, a good pneumatic excavator is well worth the time getting right, it's just so much fun to play with. It's like not playing with a toy at all, more like playing with the real thing, just smaller. How cool it that!

[Milan]

I would start again from scratch, but DON'T DITCH THE PNEUMATICS. I have built more than one excavator of a similar size and the pneumatics move at a realistic speed and with plenty enough power to dig a nice hole in my garden. I did try using LAs but, well, it was slow and boring and weak (even with motors directly attached) and too unrealistic for my liking.

I agree that pneumatics offer realistic look, and I would LOVE to have long XXL pneumatic cylinder.

Until then, this is my mechanical LA, and coupled with Speed Remote controller, it offers quite realistic speed and, IMO, look.

This is slow speed, it can operate 4 times faster.

http://www.youtube.com/watch?v=kI-o7h7Uh9o

[Alasdair Ryan]

i would like it to be cordless if possible

making another machine this size in going to be interesting i don't think i could build any smaller with out using actuators i do believe i might get the same problems again if i build a same sized machine

another thing is the weight of the thing i don't know if i can get any more power out of those drive motors

and now we cone to the switches for the rams!! as the video should the do not work well so i might need to pm you allanp to get your device idea of you

now i know why every body ant building excavators lol

i have driven real excvator that is why i wanted to biuld one for my self and make big holes at the beach

Edited November 5, 2010 by Alasdair Ryan

[Tobbe Arnesson]

this is my mechanical LA

Well done! Is it part of a finished MOC?

[allanp]

I agree that pneumatics offer realistic look, and I would LOVE to have long XXL pneumatic cylinder.

Until then, this is my mechanical LA, and coupled with Speed Remote controller, it offers quite realistic speed and, IMO, look.

This is slow speed, it can operate 4 times faster.

http://www.youtube.com/watch?v=kI-o7h7Uh9o

Ah, longer pneumatic cylinders

Sorry, where was I?

That LA looks to be a big improvement in terms of performance on the official ones, nice one

[jantjeuh]

Well done! Is it part of a finished MOC?

Yes, it's part of one of the best excavator MOCs I've seen.

Edited November 5, 2010 by jantjeuh

[allanp]

and now we cone to the switches for the rams!! as the video should the do not work well so i might need to pm you allanp to get your device idea of you

Well you could try this switch I designed.

Sorry for the lousey instructions, was my first time trying to make instructions.

I find this switch works quite well. To operate it, pulse the motor left or right. When you release power from the motor, the motor should self centre but the valve will remain on. This means you don't have to keep the motor stalled to keep the valve on. With some tweaking you can make it proportional, so that when you pulse the motor once, the switch moves a bit, pulse the motor again and it moves a bit more. This is useful to avoid anything that is heavy coming down too fast. It is also easy to return the valve to centre, just pulse the motor back the other way once or twice to turn it off.

I hope this helps. This valve is pretty much as it appeared in one of my excavators (x3) and was held together by surrounding structures. Next time i'll show you the compressor I designed for it. That should give you all the power you need for your excavator. Ta ta for now

Edited November 6, 2010 by allanp

[Alasdair Ryan]

Well you could try this switch I designed.

Sorry for the lousey instructions, was my first time trying to make instructions.

I find this switch works quite well. To operate it, pulse the motor left or right. When you release power from the motor, the motor should self centre but the valve will remain on. This means you don't have to keep the motor stalled to keep the valve on. With some tweaking you can make it proportional, so that when you pulse the motor once, the switch moves a bit, pulse the motor again and it moves a bit more. This is useful to avoid anything that is heavy coming down too fast. It is also easy to return the valve to centre, just pulse the motor back the other way once or twice to turn it off.

I hope this helps. This valve is pretty much as it appeared in one of my excavators (x3) and was held together by surrounding structures. Next time i'll show you the compressor I designed for it. That should give you all the power you need for your excavator. Ta ta for now

thanks for the help well here is what i have been working on the last few days the la is not perfected as it likes to break its self when over extended and retracted,the drive is just built quickly, i think i might use the new style tracks this time with plates added for extra width also they are 100 times stronger than the old ones i might use the black tread rather than the gray

[allanp]

thanks for the help well here is what i have been working on the last few days the la is not perfected as it likes to break its self when over extended and retracted,the drive is just built quickly, i think i might use the new style tracks this time with plates added for extra width also they are 100 times stronger than the old ones i might use the black tread rather than the gray

Well I wish you the best of luck with it, be sure to keep us posted.

[Alasdair Ryan]

i tryed you switch above but i dont work i did not have a white band as you said above but i did use a black one which is in a triangle is that a gray t peice behind the cog.

it does not whant to push the cog using those gray crank shaft parts

forgot to post pic in my last post

[allanp]

i tryed you switch above but i dont work i did not have a white band as you said above but i did use a black one which is in a triangle is that a gray t peice behind the cog.

it does not whant to push the cog using those gray crank shaft parts

Yes it is a grey t-piece, sorry again about the lame instructions.

Mine have always worked, however the black belts won't work as they are not tight enought to properly position the crank piece into the teeth of the gear. You could try doubling the belt up on itself so that the same belt goes round the triangle twice if you don't have any white belts. This might make it tight enought. Trust me tho it does work if you have the right pieces, if not then you can always tweak the design a little to make it work. So far I have not had to do that so I don't know what other tweaks to suggest.

[Alasdair Ryan]

hope you can see my pic all right thay are not the best biult it but something is wrong maybay you can shed a little light

[Tobbe Arnesson]

hope you can see my pic all right thay are not the best biult it but something is wrong maybay you can shed a little light

Yeah, if you shed a little light before taking the pics perhaps we could see. Sorry, but those photos really suck!

Try putting the object on a table with a white paper behind it.

Put a couple of lamps shining on it, but try to avoid reflexes.

Find the macro-setting on your camera, usually looks like a flower.

[jantjeuh]

It would also help if you could proofread your posts before submitting them.. some of them are a bit hard to read because of all the spelling mistakes/improper punctuation Just a friendly suggestion!

[Alasdair Ryan]

ak goys i will da that far ya

[Alasdair Ryan]

Heres the new pics

[allanp]

Heres the new pics

Ok you are almost there, i'm not sure if that red belt will be tight enought but you should be able to solve that, but the main problem I can see is that you don't have the beams on the front of it. Those beams open up the crank pieces, spacing them apart so that they are at the angle shown in my intructions. If you look at step 7 of my instructions, you will see that one crank piece rests on top of the beam, whilst the other rest below the beam. If you don't space them apart like that then the crank pieces will just try to push the gear away instead of rotating it. Bear in mind that this design is straight out of one of my excavators, those beams were prevented from coming off the axles by being part of the surrounding structures. In your last two pictures I see you have the beams, but they are no good sitting on the table . You should also space the two connector pegs holding the beams together as I have spaced them in my instructions as one of them in your picture is currently where the grey, five long axle that the gear is mounted on should go. Hope this helps.

Edited November 8, 2010 by allanp