8043 Excavator question

[DarkShadow73]

Hi all-

I have a bit of a problem with my 8043 Excavator. I modified the bucket portion with some instructions that somebody linked to the site some months ago. This would be with the 8294 Excavator size bucket. My problem is when the LA extends or retracts to tilt the bucket in and out it wiggles like crazy. I can visually see some of the many connected axles via the U-joints not turning straight and kind of 'bouncing' up and down. I have tried to isolate a non-true axle and after a lot of trouble replacing all the axles in the series all the way down to the gearing it still wiggles. I even replaced the LA thinking it was the problem. No difference. Anybody else have this problem? I didn't notice it when I had the larger standard issue bucket installed.

Thanks for any feedback.

Eric

[Paul B Technic]

I don't have that model myself so I can't give any "first hand" advice but I would be checking the gearing as it sounds like it is jamming for some reason, any chance you could upload a photo or video so we can see what I happening?

Paul

[Splat]

Hi TechnicFreak

Out Of Sight noticed that if you align the universal joints in a certain way, it can eliminate some/all of the wiggling and vibrations in the Excavator arm. See this topic : http://www.eurobricks.com/forum/index.php?showtopic=49999&view=findpost&p=885184

I followed his instructions, and it seemed to help my Excavator - perhaps this will help yours too. Let us know if this fixes your problem...

[grindinggears]

Did you follow Jurgen's instructions for his Ultimate 8043?

I had the same problem with my 8043 like you when I modified the bucket to Jurgen's version.

The reason is that one U-joint gets bent too much when the dipper is tilted towards the superstructure. Don't worry, this issue is completely normal, U-Joints can't bend by more than ~50 degrees without wiggling. So the solution is to not tilt the dipper that much or to mod the dipper/bucket by yourself. Maybe you can find a solution that's better than Jurgen's

hope I could help

[DLuders]

The yellow 8043 Motorized Excavator uses the 32030 "Technic Digger Bucket 10 x 18" (first closeup below). The red 8294 Excavator uses the 2951 "Technic Digger Bucket 8 x 10" (second closeup below, which is smaller than the 8043's bucket). Jurgen Krooshoop's "Ultimate 8043" uses the 2951 bucket.

[DarkShadow73]

My fiancee has a digital camera but I have no other mode of doing a video of it, all I can see is the bucket jitters when extended and retracted. I did try one of the newer style LA's that are lubed and it didn't help. I can visibly see the many axles connecting that subsection to the gearing on the base of the excavator wavering up and down when I activate that function. It doesn't look like an easy way to replace all the axles in the series without major disassembly and I'm not real good at remembering how it all goes back together since it is a complicated model. I could rebuild the entire arm assembly, replacing all the axles with ones parted from other sets, but that would take a lot of time and I want to play with it, the other arm functions as far as raising and lowering and extending and retracting the arm don't 'wobble' at all, just the bucket tilt subassembly, and naturally that one has the longest run of axles and u-joints. The gearing at the base of it seems to look fine when operating, it jerks a little when activating that function but as the gears spin there is no wobble in them, just everything from there on, so no idea if one of the axles are slightly bent or if a u-joint is messed up. I was extremely careful in putting this one together because it is complicated from start to finish, and decided to try that lighter weight and better looking smaller bucket on, it just looks more to scale than the front-end loader size bucket. Guess I was just curious if others had experienced this same problem and what they found to be the issue. Its not a whole lot of fun playing with an RC model that has a function that makes it look cruddy, when every other function is flawless.

I don't have that model myself so I can't give any "first hand" advice but I would be checking the gearing as it sounds like it is jamming for some reason, any chance you could upload a photo or video so we can see what I happening?

Paul

@DLuders:

Couldn't recall his name, but yes Jurgen is where I got the instructions and idea for using the smaller 2951 bucket from one of my parted out 8294's. I actually switched and used a yellow version of the bucket from an old set, the 8453 Front-End Loader from 2003 and just put the black bucket in with that set, thought the yellow one might be cool and it is the exact same size as the 8294 black bucket. But, really my question is has anyone else had this problem and if so, how did they correct it (hopefully easily)?

The yellow 8043 Motorized Excavator uses the 32030 "Technic Digger Bucket 10 x 18" (first closeup below). The red 8294 Excavator uses the 2951 "Technic Digger Bucket 8 x 10" (second closeup below, which is smaller than the 8043's bucket). Jurgen Krooshoop's "Ultimate 8043" uses the 2951 bucket.

@grindinggears:

Well i guess its common then and maybe not the axles, I didn't really think it was the u-joints, but maybe so. I actually get the vibration throughout most of its path in and out, it just looks unnatural. Great idea that Jurgen had though, it is much more realistic looking than the stock version out of the box. Problem is I'm not much good at MOC's, except simpler ones, so I can't see a better idea. I see one more post I haven't looked at with a link, so I am going to check that out too.

Did you follow Jurgen's instructions for his Ultimate 8043?

I had the same problem with my 8043 like you when I modified the bucket to Jurgen's version.

The reason is that one U-joint gets bent too much when the dipper is tilted towards the superstructure. Don't worry, this issue is completely normal, U-Joints can't bend by more than ~50 degrees without wiggling. So the solution is to not tilt the dipper that much or to mod the dipper/bucket by yourself. Maybe you can find a solution that's better than Jurgen's

hope I could help

[DarkShadow73]

Hi Splat-

Well interesting thought, per instructions I always put the u-joints in the way directions had them intended. Of course this does indeed mean taking apart the entire boom, but if it solves the wiggle problem, its worth a shot. I didn't have any issues on the dipper arm itself, just the bucket tilt, even with the larger bucket I had originally installed, though that was much heavier than Jurgen's mod, so maybe the wiggles were more noticeable since his assembly is much lighter with the smaller bucket and less 'heavier' liftarms and such. The wiggles drive me nuts as it seems a lot of people in that thread, so since I don't see an easy way to get at all the u-joints for just the bucket assembly, looks like I might as well just rebuild the entire 3 part assembly, if I recall it didn't take too long to build that part anyway, the superstructure is what took most of the build time.

Thanks to Out Of Sight for his idea if he reads this particular topic.

Eric

Hi TechnicFreak

Out Of Sight noticed that if you align the universal joints in a certain way, it can eliminate some/all of the wiggling and vibrations in the Excavator arm. See this topic : http://www.eurobricks.com/forum/index.php?showtopic=49999&view=findpost&p=885184

I followed his instructions, and it seemed to help my Excavator - perhaps this will help yours too. Let us know if this fixes your problem...

[DarkShadow73]

Splat -

Tried Out of Sight's idea of aligning the u-joints parallel and it didn't change the wiggles in the axles or the jitteriness of the bucket. I know it worked for him and can't figure why it didn't in my reconstruction, but it didn't. I am going to try and change all the axles, going to be a pain less disassembling the entire thing and starting over, superstructure not included, but the wavering of the bucket is driving me nuts. Maybe with the intended larger, way out of scale bucket it is heavier and you don't notice this, or possibly Out Of Sight didn't use Jurgen's mod for the bucket. I didn't notice it as much with the heavier bucket and attaching assembly, but the smaller bucket is so much more in scale with this model so hate to go back to the larger one. I'm not good with MOC's, so I don't see any other ideas for making the tilting/attaching assembly for the bucket any more sturdy, it is a little flimsy, but the aesthetics are much nicer with Jurgen's mod. Per another poster here I don't really see any u-joints extending any further than about 45 degrees even at full inward position of the bucket so don't really see that as the problem. I also just can't imagine how the axles could be even slightly out of round as Lego is pretty sound with their quality control, well minus the LA problem that arose when this model came out last summer, but that was unexpected too. That is one thing about Lego as opposed to its less than quality competitors like Megabloks and such, they have always put out quality parts. Every now and then you get like 1 piece of out 1000 that has a bit of flashing left on it from the molds, but I haven't come across a piece like that in ages.

If anybody has any other ideas, please let me know either here or PM.

Thanks, Eric

Hi Splat-

Well interesting thought, per instructions I always put the u-joints in the way directions had them intended. Of course this does indeed mean taking apart the entire boom, but if it solves the wiggle problem, its worth a shot. I didn't have any issues on the dipper arm itself, just the bucket tilt, even with the larger bucket I had originally installed, though that was much heavier than Jurgen's mod, so maybe the wiggles were more noticeable since his assembly is much lighter with the smaller bucket and less 'heavier' liftarms and such. The wiggles drive me nuts as it seems a lot of people in that thread, so since I don't see an easy way to get at all the u-joints for just the bucket assembly, looks like I might as well just rebuild the entire 3 part assembly, if I recall it didn't take too long to build that part anyway, the superstructure is what took most of the build time.

Thanks to Out Of Sight for his idea if he reads this particular topic.

Eric

[Splat]

Sorry to hear that you are still having 'wiggles'. I have taken apart my 8043 a while ago for parts, so I can't test this myself. Perhaps you can try these steps to troubleshoot the problem:

1. Remove the bucket, so the LA isn't attached to anything, and see if you still have wiggles.
   
2. If so, remove the LA, and test again (be careful of axles spinning around).
   
3. Then remove the axle, and test again.
   
4. Then remove the universal joint, and test again.
   
5. And keep removing parts of the drive-train until the wiggles have gone.
   
6. Whatever you removed last could be the cause of your 'wiggles'.
   

To test if an axle is straight, take it out and roll it on a flat surface. If it is bent, then you should be able to see that it doesn't lie flush on the flat surface, and doesn't roll smoothly. Also make sure all axles are fully inserted into the universal joints, and remember that gears aren't happy when they are squashed, they need a little bit of space to prevent friction from stalling the drive-train. And make sure your batteries are charged up (perhaps try new batteries).

Edited February 15, 2016 by Splat

[olaf9198]

I think the problem is that the bucket from the 8294 is 3 studs and the bucket from the 8043 4 studs is

[bord4kop]

You could also check of the LA 's.

If I recall right, the last one (closest to the bucket that is).

The problem LA I mean is attached not to the far-most hole, but second last (as viewed from the base of the LA). A mistake I made the 1st time I build it..

Mind you, I don 't know it 100% sure, so you might want to (double-)check the booklet here first ;)

[DarkShadow73]

Took everything apart, switched all the axles, making sure all were straight as suggested and switched out the LA, and still wiggles. I am really just curious, has anybody else experienced this issue?

You could also check of the LA 's.

If I recall right, the last one (closest to the bucket that is).

The problem LA I mean is attached not to the far-most hole, but second last (as viewed from the base of the LA). A mistake I made the 1st time I build it..

Mind you, I don 't know it 100% sure, so you might want to (double-)check the booklet here first ;)

[Out of Sight]

Hi, did someone mention my username??

In theory aligning the u-joints should minimize vibrations, but will not eliminate vibrations, since u-joints aren't constant velocity joints. Make sure that all axles are FULLY also inserted. This will ensure that the axles are not binding against anything,apply more friction on the u-joints themselves and spin true to their axis. A video of your problem is helpful, so we all can analyze your problem further.

As for the bucket,I stayed with the huge stocker, it proves as a good counterweight somehow, since i'm using heavier rechargeable nimh battery. But I did a slight mod to it..by moving the rotation points and increasing the leverage, I can tilt my bucket much much more than the stock, even more than Jurgens 8x10 bucket mod

To prove my point:

I can lift higher than the huge 8265 loader without spilling the load (keeping bucket horizontal)..I also lengthen the boom by 4 holes to get better 'outreach'.

Simple 5 minutes mod, more importantly it looks 'stock' and official but with a bonus capability. I've always wondered why Anders Gassedal didn't design it this way in the first place.

Edited May 12, 2011 by Out of Sight

[olaf9198]

hi a have also a problem and that is that the boom go's very slow and it is a mod

[DarkShadow73]

I did try this method, but with some of the axles/u-joints not being attached to anything, its a strange setup coming up from the drivetrain with the criss-crossing axles going to both the bucket and tilting LA's. Needless to say, I get down to the last couple axles and I can't find a way to hold them in place to see if they are the offenders. Sure I could hold the said axle between my fingers except for the last one that is a PITA to even get back onto the first u-joint and axle, but then it wouldn't spin free. Its rather driving me nuts since I paid so much for this model. I do believe it didn't wiggle as much with the stock bucket, but that one is just way out of scale for this model, Jurgen's redesign is so much more realistic. I did try to shore up and add some weight around the bucket assembly by using 5L liftarms, not the thin 5L ones and using 5L axles to hold them in place, but it didn't do a thing, thought it might be the lighter weight with the smaller bucket assy.

To answer your 2nd part I did replace all the axles with ones from my spare collection and all were true and rolled straight.

I am rather wondering if somebody's elses comment about the u-joint not being able to handle more than a 45 degree angle might be the problem. The only joint that does extend beyond 45 deg, not by a whole lot but some past, is the very last one leading to the LA.

Sorry to hear that you are still having 'wiggles'. I have taken apart my 8043 a while ago for parts, so I can't test this myself. Perhaps you can try these steps to troubleshoot the problem:

1. Remove the bucket, so the LA isn't attached to anything, and see if you still have wiggles.
   
2. If so, remove the LA, and test again (be careful of axles spinning around).
   
3. Then remove the axle, and test again.
   
4. Then remove the universal joint, and test again.
   
5. And keep removing parts of the drive-train until the wiggles have gone.
   
6. Whatever you removed last could be the cause of your 'wiggles'.
   

To test if an axle is straight, take it out and roll it on a flat surface. If it is bent, then you should be able to see that it doesn't lie flush on the flat surface, and doesn't roll smoothly. Also make sure all axles are fully inserted into the universal joints, and remember that gears aren't happy when they are squashed, they need a little bit of space to prevent friction from stalling the drive-train. And make sure your batteries are charged up (perhaps try new batteries).

Did you find anything to fix the problem? I love this mod of Jurgen's, it is elegant and more true to an excavator and this is about the most elegant looking Technic model to date.

hi a have also a problem and that is that the boom go's very slow and it is a mod

[olaf9198]

it's my own mod not that of Jurgen

and say everyting thats go wrong