Wallenstein Thumb Gen 3 on BX24 still has issues

[mswlogo]

I went to install the Wallenstein Thumb on my BX24 well aware of the sliding issue. This "Third Generation" design is supposed to fix the sliding issue.

I get the thing on there and just hand tighten the bolts and check how the new plate prevents it from sliding down where the high pressure fitting comes very close. With the bolts just hand tight it can still slide down to the fitting. It just started to "wedge" (against the new plate) just as it approached the high pressure fitting. So I thought I'd crank the bolts down and see how it looks and feels. As I was cranking the bolts down. It dropped (i.e. it lost the wedging, what the f*. The other side has a welded plate that is wider than the dipper stick. It CANNOT clamp on the dipper stick properly, it's too wide. As you crank the bolts it has to bend and only touches the sides of the dipper stick at the bolts.

You can see with it partially clamped down, I can slip in a 3/16 drill bill. This gap should be zero. You cannot clamp it tighter on the thumb side because of the welded plate. This plate should float and two more bolts on the other side.

I'm debating if I should make a shim for it or return it and get a bro-tek. I really like the unit.

Welding is not an option for me, the dipper stick is very thin and I would not weld to it.

See pics attached.

 

[TINYTRACTORSERVICE]

OK I was going to Waite till I got this and then see if this worked ? but I will let you all no now. I talked to EMB MFG INC. (Wallenstein) about this and they are hooking me up with maybe a fix for this. I Will show you a pic of what they are sending me ASAP may have went out today? He told me //We will be shipping the wedges to you early next week. Please assemble thumb with the wedges tight in place and report your findings to me.



Thanks and have a great Thanksgiving! (When I called you I had forgotten the day - it is not a holiday for us here in Canada).

Regards, It was 5:30am T-day when he called me LOL

 

[mswlogo]

Thanks for replying, but that new shim you showed, in my opinion, should span the whole side of the dipper stick. It's encouraging they keep trying to fine tune this thing, but geesh.

The thumb bracket is a fairly rigid square U. The base of the U is too wide (as you must know). You want to use the sides of the U to help clamp it. But the shim you showed only fills the gap at the base of the U and the top of the U will still have to bend over (still leave the side grip hollow). You still won't get a good sandwhich clamping action, because you can't squeeze the base of the U. Then need a shim that makes the whole U narrower.

 

[mswlogo]

Actually after looking at the drawing you posted again, it doesn't looks like they tried to fill the gap (where I put the drill bit) at all. It looks like some sort of wedge to be able to wedge against the taper of the dipper stick. It needs that TOO. As I described in the beginning of my post that it didn't wedge quite soon enough. You could easily fix that with a shim under that new small plate the bolts go through (or use the fix they are sending you). Once you get it tightly wedged, you want to clamp it firmly (and SQUARELY) on the sides so that it does not losen up over time. I don't like the way it's clamping.

 

[robbieo11]

WHY
did they not utalize the pin that is rite there insted of all the clamping

put 1 clam on the"highest" point of dipper then use the pin that holds cylinder arm for point 2
there promlem solved use longer pin and go outside of existing bracketsog pivot arm

 

[ndnparts]

Last weekend, I welded a stop on my BX24 dipper to lock the Wallenstein thumb so it couldn't damage the hydraulic fitting. I also saw a recent post where someone had bent the black positioning arm on their thumb, so I took a good look at mine, and I noticed that the area in the center with the two pin holes did not have the center portion (between the two holes) welded to the main body of the support arm. I believe this creates a weak spot due to the wide span, and may have contributed to the bending that the other post refered to. So, if you have a welder, you may want to consider welding this center area to the base for extra support. I did this, and the bead does not interfere with the pin insertion. The force is actually from the opposite direction, but if welding can stop any flexing, it won't hurt. Stan

 

[mswlogo]

The new support arm is way beefed up (I think this is Gen 2).
Gen 3 added the plate to try to wedge it sooner but it wasn't quite enough (alas Gen 4 beta posted above).

I think I'm going to attempt to fix mine by the following.

There is a collar that holds the main pin that the thumb swings on.

This collar is welded in place.

I plan to cut a 1/4 inch out of the center of this collar and leave it floating.

This will allow the bolt right near that collar to properly clamp the dipper stick.
This is why the Wallenstein Thumb moves and the Bro-Tek doesn't !!! The wallenstein is not squeezing on both sides of the dipper stick.

It never should have been welded and adds no strength to the design.

The bolt near the collar as designed (with welded colar) is completely useless (it just tries to crush the collar which is not possible).

The same thing (problem) is true at the other end where a plate is welded in place between the two side plates. I considered cutting a 1/4 inch out of the center of that too and then adding bolts behind it. But I think the bolts are far enough away from that plate that it will conform to the dipper stick when I clamp it down (i.e. the two plates will bend slightly).

Even with a welded stop I wouldn't be happy with the way it clamps as is. If it clamps properly I don't think it needs a welded stop. And I tend to agree with Bro-Tek's warning on their e-bay ad to NOT weld anything to the dipper stick as you may weaken it (it is very thin).

 

[ndnparts]

The easy fix for the adjusting arm is to place heavy wall tubes in the two center holes and weld them all the way around, which will create a solid bridge. This will require some machine work, but since I don't have any bending problem, I haven't bothered with it. If you don't get heavy handed on the dipper stick weld, it isn't a problem to weld on it. Actually, you probably have a better chance of causing damage by applying too much clamping force to it. Either way you want to slice this, I have moved about 40very heavy rocks and have not had any damage and the thumb can't slide and damage my hydraulics. Stan

 

[mswlogo]

I agree over clamping (risking a kink in the dipper stick) is just as risky. That's partly why I want to get the clamping "square". The way it's designed it puts too much stress on one side (piston side) to hold it on there and none on the other side (thumb side).

 

[mswlogo]

Surgery success !! I did a quick test curling the bucket as hard as I could against the thumb and it didn't budge. Only time will tell for sure but it looks very good and I could perfectly understand it sliding the way it was clamping before. It basically clamps like a bro-tek does now. No welding and no wedges. It conformed (bent into shape) just as I had hoped because the plate on the other end has the same issue of being too wide and I did not cut the plate. But there is no bolt near the plate anyway. The nearest bolt managed to bend it enough to clamp flush.

Pic 1) Shows it with the cut (done on table saw with metal blade).

Pic 2) Shows how the side bracket is nice and flush to dipper stick.

Pic 3) Shows how the other side bracket is nice and flush to dipper stick.

Pic 4) Shows how the collar I cut collapsed as I clamped it down against the dipper stick. You can also see a gap that got created between the outside of the side plate and the collar on the thumb (on the right). This gap does not hurt anything (adds a little side play on the thumb). This new gap on the right also shows how much it was too big for the dipperstick (~3/16 inch). I would have liked a little gap in the collar when finished to be sure all the clamping force is against the dipper stick. But it was kinda of nice it closed the cut perfectly.