8043 Excavator - Lego update

[jason-l]

I emailed Lego UK's customer services a couple days ago, explaining my experiences and problems with the Excavator. Received what appeared to possibly be an automated email - just generic comments with no specific response at all to by issues and the 8043 set (I may be mistaken, but that's how it read) It invited me to phone them, quoting the email's reference number.

Perhaps I'll give them a call on Monday.

[grepin]

Oh well, mine was ordered on Thursday, but by the time I finally manage to start building it, LEGO will probably already have released a fix.

In the mean time, it will remain sealed

[hoeij]

I wonder, if you buy this set from eBay or from bricklink, would you also receive the updated parts when they arrive?

Edited August 23, 2010 by hoeij

[TechnicJuan]

Toy R Us just stocked 2 more of these here today.

[n8n8]

Just adding what i got from Lego. Theyre saying its an actuator problem..

Thank you for getting in touch with us.

First let me apologize for the difficulty you've had so far with your new 8043 Motorized Excavator.

Our design team recently became aware of this issue and removed the item from our LEGO.com shop.

We're now working really hard to redesign the linear actuator - the source of these motor problems! We expect to have a solution up and ready within a few weeks.

If you would prefer a refund or exchange for the set this can be arranged, but we would love to see your set completed and fully functioning. Since you've asked I'm going to put you on our list for those replacement actuator arms to save you from having to get back in touch with us. However, if this isn't enough and you would rather get a refund or discuss the issue further with us please use your reference number XXXXXXXXXX and reply to this email - or give us a call and we will come up with a solution that works for you!

If you do decide to wait for the replacements it shouldn't be more than a few weeks before you get that actuator in the mail; and as I mentioned before, you're already on the list to receive these replacements.

Happy building!

[TechnicJuan]

I wonder how much this debacle is going to cost TLC? I find it hard to believe that they didn't test this out before releasing the set.

[Zerobricks]

Can someone compare the older LA's with these from 8043?

[andythenorth]

I wonder how much this debacle is going to cost TLC? I find it hard to believe that they didn't test this out before releasing the set.

Engineering is difficult.

[backbone]

Can someone compare the older LA's with these from 8043?

I have 10 LA (8264,8265,8258,8043), and i noticed no differencies between them.

[GuiliuG]

Yes, all the LAs are the same but they are all bad^^.

The change of the las is a really good thing for the builder.

[eMHa]

Perhaps they realize now that the LAs have a poor performance under load? My first impression (on set 8264) with the LAs was that I thought they are made very cheap.

It is possible that TLG has locally produced parts

which are perhaps better than the parts made somewhere else!?

Nevertheless, it's good to see that TLG has found the weakness (in the LAs) and is going to fix it. Someone here also said that with disconnected LAs the axles turn normally, so it is plausible that the LAs are the (main) problem. Also that the problem occurs after awhile of playing seems reasonable for bad LAs.

So my hope grows that TLG will soon release the fix and sell again the set.

[jason-l]

I just had a reply to my second email from LEGO, a quote from it below:

I'm sorry there was something wrong with your new LEGO® set. We are aware that there is indeed a problem with this set; our designers have already identified the problem, which lies with the linear actuator. I have already asked for a service bag to be sent out to you, however this could take 2-3 weeks before this arrives with you, as we currently are experiencing a backlog.

This is an impressive response - many companies would try to sweep this kind of thing under the carpet. Bravo LEGO!

Of course, one thing does occur to me... Like many of us, I also own 8053 (Mobile Crane) and 8265 (Front Loader). That's 4 other presumably 'defective' LAs. If the new versions look identical on the outside we're going to end up with 'good' and 'bad' LAs mixed-up in our spares/sets with no way of telling which is which. If LEGO were to replace ALL LAs sold with ALL Technic sets to date, it could be tens of thousands?? So I doubt that will happen!

[allanp]

I wouldn't say the LA's are "devective", the quality seems up to Legos usually high standards. I'de say they are just inefficient, especialy under load due to the internal friction. Maybe adding grease would help for a while but not sure how best to solve the problem long term, unless you remove the screw thread, add a few seals and ports and make them a bit longer!

Edited August 21, 2010 by allanp

[Sato]

And how does defective LA's explain the problems people are having with slewing and track movement?

[rgbrown]

And how does defective LA's explain the problems people are having with slewing and track movement?

Potentially the defective LAs damage the motors that are driving them (if they overheat)

[Parax]

I had the 8043 running constantly for a whole day before it started to get a little 'rough' initially I thought the actuators had become out of sync (they need to work exactly together), but further testing has revealed it to be a power & friction issue. I really like the set and do want to keep it, but I fear that it will not be easy for Lego to fix. Which is a shame as it may scare them from producing such complex sets again.

I do think there is too much friction inside the LA's possibly more threads are required on the shaft I think there are 2-3 equalling about 4-5mm² contact area! increasing this to at least 6 threads would help a lot! doubling or even tripling the screw thread contact area would vastly reduce the thread pressure and hence friction, and using a more precise metal threaded sleeve instead of the (deformable under pressure) white plastic would definitely help a great deal.

I also think that there is a quality issue with the motors. some do seem weak as Conchas noted here there is no reason for this as motor technology is really good these days. (just look at RC cars) by using slightly more expensive($2-$5) materials these motors could perform tremendously well.

The Third concern that I have found is the gear train friction, which is a significant loss in some cases. Oddly I found that sometimes binding can occur in certain directions, This is most obvious by selecting the neutral gear position so everything should turn freely, and then manually turning certain features. By doing this I noticed that one track turns freely in one direction but can stiffen/bind when turned the other way. Also there is a lot of 'cross torque' being fed into other axles presumably from stiff idlers, perhaps these could do with a redesign? (maybe its time to loose the now redundant teeth too?) although this does not seem to be a problem on the main boom lifting gear train.

Finally, If Lego do make alternative versions of the LA's or Motors I hope they will use a different colour scheme! perhaps reverse the Greys? dark Grey actuators with all Metal internals would be appreciated, as would dark grey stronger motors (maybe neodymium magnets?). both of these would be more expensive than what they are currently producing, but would be a better quality, for a few dollars more. And most importantly to this thread would enable the 8043 to remain the same.

Parax.

[CP5670]

I guess we were right about the LAs. It did seem to me that they struggle in 8265 too, especially compared to the similar but worm gear based mechanisms in the old 8862. Although it's strange that nobody in the community has really commented on this earlier. The LAs have been out for over two years now.

The new LAs will probably have a different part number, but I don't think they will make any obvious external changes. TLG has revised parts like this before and the revisions have looked nearly identical. (the 9V gear motor and damped shock absorbers come to mind)

And how does defective LA's explain the problems people are having with slewing and track movement?

I wonder if the LAs are the only problem they are going to fix. The slewing function also needs more gear reduction from what I've seen in the videos.

Someone also said that the function switcher does not always lock all three transmission rings into place. I'm actually a bit surprised that they used the standard transmission setup there. Before the set was released, I was hoping they would introduce a new axle joiner piece without ribs, allowing the rings to slide over them smoothly.

[Meatman]

I was hoping they would introduce a new axle joiner piece without ribs, allowing the rings to slide over them smoothly.

why can't you just use the new styled axle connectors? the rings seem to slide over them smoothly.

[Erik Leppen]

why can't you just use the new styled axle connectors? the rings seem to slide over them smoothly.

I thought the new axle joiners were a bit thicker; this would mean the "clips" on the driving rings are under constant pressure. This could damage the part over time.

Also, a free-sliding driving ring is not what you usually want in other constructions, because it couldn't be set in a neutral position reliably

[Meatman]

I thought the new axle joiners were a bit thicker; this would mean the "clips" on the driving rings are under constant pressure. This could damage the part over time.

Also, a free-sliding driving ring is not what you usually want in other constructions, because it couldn't be set in a neutral position reliably

true, but in this case the 8043 doesn't have a neutral position. I was just tinkering around with a driving ring and new axle connector and I am not quite sure how this could become damaged over time. they seem to slide effortlessly. what pressure do you mean?

[roamingstop]

If they do an LA design perhaps they should also consider some form of back-drivable / harmonic drive system. With good design they can drive quite high loads - but also provide 'free movement' without damaging motors.

I guess it will take some time to resolve - if a new LA design is needed that would not be quick (unless one was already in the pipeline). If simple changes to transmission then it could be released in a easier way.

But for me, the beauty of the model was also the technic gear trains / transmissions and functionality packed into a great superstructure. The model could provide a lot of inspiration - just a pity it needs a bit more development time. And I hope it does not scare TLG too much - but who knows for the future.

[allanp]

doubling or even tripling the screw thread contact area would vastly reduce the thread pressure and hence friction

Wouldn't increasing the area increase the friction? Like increasing the width of a car tyre to get more grip.

[rgbrown]

Wouldn't increasing the area increase the friction? Like increasing the width of a car tyre to get more grip.

Not really. If the screw behaves ideally, then the friction is proportional to the normal force exerted by the screw. Increasing the number of contact points by a factor n will divide the normal force by n (assuming the load is distributed equally between the contact points), and summing them up will give (in theory) the same friction.

[moebiusfactor]

Hey everybody, I just joined, in fact, I had to- the alarming number of complaints on this set scared me, and since I have a few issues of my own, I had to know. Apart from the LAs, From day 1 I had the problem with the left track working at a very slow pace- now, it's as if the motor is struggling to turn it, when on the right, it all works fine. I only know so much about mechanical engineering- is this supposed to be normal?

[allanp]

Hey everybody, I just joined, in fact, I had to- the alarming number of complaints on this set scared me, and since I have a few issues of my own, I had to know. Apart from the LAs, From day 1 I had the problem with the left track working at a very slow pace- now, it's as if the motor is struggling to turn it, when on the right, it all works fine. I only know so much about mechanical engineering- is this supposed to be normal?

Well it shouldn't be doing that but I think it's a quite common problem with this set. It could be the design of the gear train to the track or it could be the motor that powers that track has become weakened by driving the LA's in the other mode.

One thing i'm wondering as it is not clear in this thread (or I have missed it) but the track that is not driving as it should, is it the track driven by the same motor that drives the pair of LA's that lifts the arm?