[MOC] Bucket Chain Excavator (DONE)

[doug72]

3 hours ago, I_Igor said:

I told you in the past that I'll keep an eye on this project and must say great effort for this project. Usually big projects give big responsibilities and you shown that you are responsible with such level of perfection 

 

2 hours ago, Aventador2004 said:

@Doug72 great work, I don't know which I like better. Bwe vs bce showdown.

Thanks to both of you for your comments - much appreciated.
Its an epic build which can be very frustrating at times and very rewarding when things work as envisaged.

Doug

 

[jotta93]

Good job Doug,! 

One thing though: I thought you were going to build it resembling the MAN TAKRAF from the earlier posts. If so, I have a suggestion (which you may have tried already): you could lower the pivoting point of the chain and place it in front of the base unit, keeping the upper part static so that you could build the discharge mechanism under it, like in the picture

[doug72]

26 minutes ago, jotta93 said:

Good job Doug,! 

One thing though: I thought you were going to build it resembling the MAN TAKRAF from the earlier posts.

 

Thanks, yes it way to high at the moment. Just have to sort out position of the discharge conveyor drive motor, then I will attempt to lower the bucket ladder as per the Man takraf machine.

Problably have to re-design the discharge housing.

 

[doug72]

On 09/05/2017 at 9:56 PM, jotta93 said:

Good job Doug,! 

One thing though: I thought you were going to build it resembling the MAN TAKRAF from the earlier posts.

Discharge conveyor now working as per BWE ie. Lock / unlock, manual with drive fom M motor now installed.

Now re-designed the discharge housing similar to the MAN TAKRAF machine. Bucket ladder shown in position but not yet connected.
Next is figure out the bucket chain run, I hope to keep the tip forward to discharge balls but if not possible then may have to modify the buckets.
 

Edited May 11, 2017 by Doug72
added image

[jotta93]

Much better Doug, looks a lot like the real machine 

Keep it up!

[doug72]

Update:

Getting very close to perfecting the bucket chain path through the discharge housing so that the balls unload from each bucket at the front.
It has taken a lot of trial builds / test / failure / start again but I finally think it is possible without any modification required to the buckets.

BUT I HAVE A PROBLEM:
The way each bucket is attached to the chain uses 2 x Pin w/ hole connectors with a 5L x 0.3L beam as a spacer. to ensure a tight connection to the track link.
The ends of the spacers snag on the start of the various beams use to guide the chain along the ladder and up into the discharge housing especially where the chain bends backwards.

What is required is a 3L x 0.5 beam which has three holes instead of XOX which will still guide the bucket along the guide rails but not snag.

Did a test mod on one spacer and works as well, the bucket rises up from the ladder into the discharge housing high enough to clear everything and just before reaches the drive sprocket the chain dips allowing bucket to tip forward and discharge balls.

Tested with both old and newer style large track treads and works OK.

 

There is finally enough clearance for a short guide chute to drop balls onto the discharge conveyor.

Hope this all makes sense.

Question:
Are 3L x 0.5 beam available with OOO configuration. ?
Should I modify and cut down 5L x 0.5L beams to give 3L x 0.5.
Has anyone other ideas of providing a Lego legal spacer 3L wide x 0.5 for the Pin with hole connectors.

Bucket Ladder:
Now rebuilt longer with a tensioning device for the return spocket wheel. This allows the chain to keep in contact with the return sprocket wheel at all positions between horizontal and 45 degs down. As a resuly the braided cord I have is too short !
More on order from eBay. 

Edited May 14, 2017 by Doug72

[doug72]

17 hours ago, Doug72 said:

Question:
Are 3L x 0.5 beam available with OOO configuration. ?
Should I modify and cut down 5L x 0.5L beams to give 3L x 0.5.
Has anyone other ideas of providing a Lego legal spacer 3L wide x 0.5 for the Pin with hole connectors.

Answers:
Cannot find any listed
NO
None yet.

Solution:
In order to comply with Lego Purists and be Lego Legal I have devised a new way of connecting each bucket to the bucket chain that eliminates to 5L x 0.5 spacer.
Also is much better at guiding each bucket along the guide rails. The 5L x 0.5 spacer tended to snag around tight turns.

IMG_4592 by Doug Ridgway, on Flickr

IMG_4593 by Doug Ridgway, on Flickr

[doug72]

Bucket ladder video: NEW
Tested and working OK.

After individually checking every single track tread in my possesion including from previous models, MOCs & GBCs  I found  had enough of the old links for the bucket chain. 
Needed these as they can bend "backwards" more than the newer type.
Nine buckets are now fitted and evenly spaced on the chain
Just some minor fine tuning tidy up some connections and try to eliminate the jerkyness and, which is caused as the back of each track link on the "bent backwards" section, as they pass over the ends of the guide rails.
Guide support at bending point only 3L long (might try a 2L or 1L ) - pity curved beams not available. Can't use rollers as would foul the buckets as they pass.

Upper support rollers added to keep top part of chain run from rubbing on the lower chain run where they are close together.

Works OK when bucket ladder horizontal but some angle down is required when operating to keep balls in the buckets.

Had to raise the drive sprocket in order to get enough space for a ball collection chute which still to be install.

Video shows the bucket ladder and almost its lowest angle.
Awaiting longer cord to use for the hoisting system.

Next step, install PF receivers, operators cabin, machinery house and ladders / guide handrails etc.

 

 

[Aventador2004]

That looks a bit slow, will you change gearing for less shaking?

[doug72]

4 hours ago, Aventador2004 said:

That looks a bit slow, will you change gearing for less shaking?

Batteries might be running out from the many tests runs.

Edit:
Batteries now changed and speed much better.
Also lowered by 1L the top return rollers and changed the 3L guide beams to a 1L beam + an 11.2 Wheel hub giving a better guide geometry for the chain with less shaking.

Present gear ratio is 24:1 using older worm & L motor.

Now I have the newer worm gears could try 20:1 ratio but will have to design a new gearbox.

Edited May 16, 2017 by Doug72

[jotta93]

Well done! It's actually not that slow compared to the real machine, but I guess you could try a 20:1 reduction using the new worm gear.

Have you tried to elevate it? Does it also go 45º upwards? And will the chains bend that much, especially the upper one?

Keep it up!

[doug72]

18 minutes ago, jotta93 said:

Well done! It's actually not that slow compared to the real machine, but I guess you could try a 20:1 reduction using the new worm gear.

Have you tried to elevate it? Does it also go 45º upwards? And will the chains bend that much, especially the upper one?

Keep it up!

I'l keep the chain drive gearing as it is as it would be quite a task to rebuild for a different ratio due space constrainsts.

Just tried the bucket ladder at 45 degs upwards and runs OK but no way would balls stay in the buckets !!!!
The upper run of the chain dips down to the hinge point & bends back up again without any problem.
Due to the increased chain slack when 45 deg up, each bucket as it goes around the return sprocket drops slightly before entering the guide rails.

The shock absorber chain tensioners only has about 1.5L travel and just right for when bucket ladder is 45 deg. down.
 

Edited May 16, 2017 by Doug72

[Hay Ewe]

yep - looks great!

I have enjoyed following this project so far, for me a proper project - taking a real world machine and making it in Lego.

Looking foward to the finished project

 

[doug72]

10 hours ago, Hay Ewe said:

yep - looks great!

I have enjoyed following this project so far, for me a proper project - taking a real world machine and making it in Lego.

Looking foward to the finished project

 

Thanks for the comments.
There were times when I thought it was impossible to build without resorting to 3rd party or 3D printing but have managed to build it using  99.99% Lego legal  parts - just the hoisting cord which s 3rd party because the Lego cord I have is too short.

Looks like I will have to shift the position of the two M motors for slewing & hoisting higher up in the side frames to be able to connect them to the PF Rx without using extension cables.

Main problem after I finish building it is where to display / store it !
Its 90 cm length x 40 cm high x 30cm wide and no idea how many parts used.

I will probably make seperate videos showing each function, i.e. travel, slewing, hoisting, digging,  as i only have a hand held compact camera to take them.

[Hay Ewe]

look forward to the video clips.

Storage, I suppose its down to the individual, I keep my builds for  awhile and then strip them down to store easily or build something else.

[doug72]

2 hours ago, Hay Ewe said:

look forward to the video clips.

Storage, I suppose its down to the individual, I keep my builds for  awhile and then strip them down to store easily or build something else.

I'll keep this for awhile but eventually it will be broken down to build something else.
Its been a useful exercise in problem solving.
Motors for hoisting & slewing now re-positioned higher up.

[jotta93]

I can't wait to see it in action!

[doug72]

48 minutes ago, jotta93 said:

I can't wait to see it in action!

Be awhile as have had a bit of a set back.

The bucket ladder is quite heavy and is tipping the structure forward when held up by hoist rope.
The wedge wheels used on the BWE design that roll along the edge of gear quadrants are not up to the job and keep slipping off, causing the slewing to jam.
Substituting the wedge wheels with disc wheels with tires that have more contact on the gear quadrant  (same as used under the conveyor) which should help stop the tipping forward.
Also working out the counterweight needed to balance every thing better when the bucket ladder in place.

Slewing & hoisting motors now re-positioned and PF switch and PF Rx installed.
 

[doug72]

Slewing problem resolved:-

Tried changing the wedge wheels to disc wheel with treaded tires but found the sides were catching on the gear quadrant connectors at four points when slewing.

Reverted to wedge wheels again but double up, i.e. 2 per axle at three locations.
The 4th location with the rubber tire wheel required for the discharge conveyor positioning system was changed to a smooth tire which does not catch on the gear quadrant connectors.

Still had problem it as it would not slew 360 degs. due to the 12T double bevel gear losing engagement with the gear quadrant teeth at one point.

Finally found that due to where I had positioned the PF Rx for the caterpillar track drive.

The BWE way of securing the gear quadrant at that point to the under carriage could not be used.

Results was that under load the gear two quadrant at that point flexed outwards enough to disengage the 12T gear.

Now fixed securely by an alternative method with pins and axles to prevent flexing movement.

Slewing tested extensively today with bucket chain in place and has shown rotating structure has to be well balanced.
At present slewing by M motor has is 20:1 x 140:12 - overall approx 233:1 and is a bit little fast.
Can slow this by adding a 12:20 gears in right angle drive from M motor to give approx 388:1 reduction.

Three full battery boxes are required to counter balance the bucket ladder.

Slewing / hoisting / travel all functioning correctly, just some minor fine tuning to sort and
tidying up PF cables runs, add operators cabin, handrails, ladders etc.

Hope to post videos in next few days showing each function.

 

Possible improved ball unloading from buckets:-
Whilst further testing I noticed that occasionally balls did not roll out of the bucket from the front edge but still ended up on the discharge conveyor !

Discovered they had exited the bucket AFTER the bucket had passed around the drive sprocket.

As each bucket after passing around the drive sprocket and starts its decent the balls roll out of the back of the bucket into the gap between edge of the bucket chain and the housing before dropping down on the collecting chute above the discharge conveyor.

If this proves workable it will negate the need to bend the bucket chain backwards as much and should  make the bucket chain motion less jerky & much smoother.

The new way of attaching the buckets to the chain is the secret and along with a small addition to the chain fixings by dividing the bucket into two sides the balls can fall off from each side.

Collecting chute will need slightly extending to catch the balls.

I will modify 4 buckets to test and prove this discovery.

Doug.

 

 

The bucket ladder is being held up by the hoist ropes which are WHITE hence invisble on the white background !!!

Edited May 20, 2017 by Doug72
Image added / added content

[doug72]

“The Mega Machine Awakes”

At long last got to the stage where its all coming together - video now made showing the slewing, raising & lowering of the bucket ladder and the bucket chain in motion.
Bucket chain is 108 links in length with nine buckets.
Bucket discharge over the top is feasible. Had to raise the drive sprocket and re-position the L motor worm drive gearbox to achieve this.

This gave more room to better position the ball collection chute.
Almost there adjusting the guides to ensure balls after falling out of the bucket drop onto the chute below.
Balls are loaded by hand at the moment but will devise a way for buckets to scoop them up.

The rotating structure has to be well balance to ensure it rides well on the turntable gear quadrants.
Clearance over the battery box in the lower structure is very tight.

The whole machine is quite heavy and and is built on a modified BWE base and if I built it again I would make a stronger more rigid structure.

Bucket ladder can be positioned from 45 degs. up to 45 degs. down while chain is moving.

M motor for hoisting system moved higher up the structure to avoid need for for an extension cable, the 6 fold pulley system to raise & lower the bucket ladder is adequate.

Enjoy the video which made using a hand held compact camera.

 

As per the actual machine its noisy !

Another video will be later made to show the machine travel and steering

 

 

Edited May 22, 2017 by Doug72

[jotta93]

I love it! It looks a lot like the real thing, only some minor aesthetic details needed 

Did you have to modify any of the buckets?

[doug72]

43 minutes ago, jotta93 said:

I love it! It looks a lot like the real thing, only some minor aesthetic details needed 

Did you have to modify any of the buckets?

Thanks,
I have yet to start the aesthetics.

At the moment I am having a big tidy up getting all the many loose unused parts back in their storage boxes, bins.

Operators cabin next, then machinery housing ( to hide counterweights) and ladders and handrails.

Re buckets, no cutting, only modified using only Lego parts to divide into two compartments.

Ball discharge is now working over the top OK once  I got the ball guides aligned properly to direct them down onto the chute below.

Have an idea for a ball loading hopper and once proven & reliable will post a video.

Tested the tracks and it crawls nice and slowly, and can make easy turns if use a train controller.

Estimate over 4000 parts used !!

Edited May 22, 2017 by Doug72

[agrof]

Great to see it alive! It is just as impressive as the 42055 itself, or actually even more.

[Gabi_BC]

This looks great! Congrats!

[doug72]

Details of how buckets are attachment to chain.
The centre yellow part separates the bucket to prevent balls getting trapped and ensure they roll off at the sides of the bucket.

Turntable Ring gear:
If I re-built this MOC I would recommend using two stacked layers of gear quadrants to bear the heavy weight and stiffen up the rotating structure.

This allows you to eliminate the four LEGO Black Technic Cross Block 2 x 2 x 2 Bent 90 Split (Pin/Twin Axle) (92907) to provide a wider track for the support wheels to roll along without fouling.  Lower gear ring attached using pin holes same as before. 

Edit: For maximum stiffness overlap the joints between upper and lower gear rings.

Only downside is the gear teeth between the two layers don’t align but the slewing gear can still engage with the upper gear ring OK and  have plenty of clearance over the supporting structure & the battery box below.

 

Edited May 23, 2017 by Doug72
removed image file info