Importing and modifying a new mini excavator from China

[dfkrug]

Proof is mostly for math and alcohol imo, but yes it absolutely improved the functionality/usability/comfort for mine. I still did add the adjustable valve to reign in boom function afterwards- it was just still a lil too touchy for me.

Anytime you can run an experiment after changing only one variable is a good thing. I would not have expected that adding 15% ballast in the back of the house would have such a noticeable effect.

The best ways to reduce the jerkiness further would be to lower the flow rate by installing a smaller pump, adding shock-RVs on the most offending circuits, or adding an adjustable 2-stage pump, respectively, IMO. A distant last choice would be to add restrictor orifices to the offending work ports. The last choice robs power and add tons of heat. I have some adjustable flow restrictors here and have tried them on other applications. Note that many of the hoses on these minis are only 1/4", which already restricts the flow.

 

[Fredrik]

Did you make a mold for the molten lead, or improvise and cut, as JAYLAST did? Very resourceful on the lead scavenging.

Simple answer is ......yes. The scrap was free for the taking but I had to take it all. still not a bad deal.

 

[D'oh]

I think I am going to Raid our Wheel Weight Bucket. Every Mount and Balance done at the shop requires removal of the old weights.

I just have to figure out the Melting Pot.

I plan on a Sand Mold, being that the Cabin has a Beach.

 

[dfkrug]

I think I am going to Raid our Wheel Weight Bucket. Every Mount and Balance done at the shop requires removal of the old weights.

I just have to figure out the Melting Pot.

I plan on a Sand Mold, being that the Cabin has a Beach.

You could make your own oil sand for casting. I have not done aluminum casting since shop class in HS, and that was in the early 70s. I did enjoy it.

Now I want a lead weight to add to my steel plates. 100# more weight would be great. I would prefer a sand mold with just the right curve and width, but cutting plates with a saber saw also looks very easy. I have a huge pile of dead lead-acid batteries, but dunno if I want to go thru the effort of removing the plates.

Kudos to our 2 ballast pioneers, FREDRIK and JAYLAST.

 

[Fredrik]

You could make your own oil sand for casting. I have not done aluminum casting since shop class in HS, and that was in the early 70s. I did enjoy it.

Now I want a lead weight to add to my steel plates. 100# more weight would be great. I would prefer a sand mold with just the right curve and width, but cutting plates with a saber saw also looks very easy. I have a huge pile of dead lead-acid batteries, but dunno if I want to go thru the effort of removing the plates.

Kudos to our 2 ballast pioneers, FREDRIK and JAYLAST.

Sand molds for aluminum I've done were a mixture of ..sand, bentonite clay and baking flour. I'll see if I can find the exact recipe. Probably online some where.
Look for green sand mold recipe.
Melting pot can be a large coffee can or any steel pan for that matter. Remove the dross( floaty crap on the surface) with cold steel rod(rebar) and comb or rake ( dollar store stainless slotted spoon) out the metal clinchers.

 

[jodieadair]

Has anyone here needed any undercarriage parts? I have been able to find local sources for many parts but nothing on the sprockets, idlers, rollers, tensioner. Even the Chinese resellers have told me they just keep a spare parts machine for things like that. I don't need any parts yet but I sure don't want to be looking for parts after something breaks.

 

[jodieadair]

I guess they act like a check valve when there isn't enough driven hydro pressure to open them. Gravity alone can't open them.

Almost a necessity sometimes. The sinkers and thin stuff are super easy to get melted compared to a 50lb ingot but it all melts long before steel/tin in open air.
The biggest challenge was finding an appropriate mould without fabbing one. Pics of an old paint tray below that worked good for a wedge shape. Very easily trimmed the result with a circ saw.
Since drilling for me tended to melt the lead and seize the bits I just added the posts when liquid on the last one.
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There's about 200lb on center and rear of house floor and 150lb more easily seen in pics centered on the back.
It made a huge improvement dampening the inertia from fast and or fully loaded main boom movement that used to rock or tip the 2200 lb machine.
The HT looks like it has alot less steel at the rear than mine, but also quite a bit more room to play with. Just using the thing and starting to add weight I'm sure you'll get a feel for it. You went too heavy (or main RV pressure too low!) if you can't easily track with the extra weight or the blade can no longer lift machine.

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Straightening frame tails. They both consistently had bent a few degrees outward- I'm beginning to wonder if it wasn't from something like hard jump turns due to the consistent force they exert VS the inconsistency of binding the tracks up many times at random in both directions of travel.
Also, during removal and install of the tracks for this repair I had some trouble with binding the tracks again in both directions and to full stop, even at the newest high pressure setting of 2900psi 19.99bar.
There wasn't really any apparent side forces at play when binding/bound.

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Either way a 4t chain binder pulled the frame in easily, and I added some 3/8" flat stock gussets top and bottom for now. Could be much more heavily gusseted but it was cold and windy and not close to any power for tools/welder.

When demoing a rather thick and reinforced slab foundation for an old shed I turned up double pump cutoff to 1700psi and main rv to 2900psi. Wow I feel like it's so much more powerful fast and smooth than from stock now with all mods and adustments. Well worth.

I've noticed that the newer machine have a redesigned sprocket section, it apperas to be much more robust. See attached pics. Do you think it would still be wise to add bracing accross the rear to keep the spacing.

 

[dfkrug]

I've noticed that the newer machine have a redesigned sprocket section, it apperas to be much more robust. See attached pics. Do you think it would still be wise to add bracing accross the rear to keep the spacing.

My 6yo sprocket has no holes and weighs 21#. Seems more robust than the new ones. What does yours weigh?

I bought spares of most things I thought could break and not be fixable locally. The frame bracing I have is on the outside and is not very stout, due to interference with the sprocket. Small rocks easily get in there. Adding some inboard bracing seems a good idea.

 

[jodieadair]

My 6yo sprocket has no holes and weighs 21#. Seems more robust than the new ones. What does yours weigh?

I bought spares of most things I thought could break and not be fixable locally. The frame bracing I have is on the outside and is not very stout, due to interference with the sprocket. Small rocks easily get in there. Adding some inboard bracing seems a good idea.

I meant the metal that the sprocket mounts to. The sprockets themselves definitely look worse on the newer ones.

 

[jodieadair]

The pic with the bent metal is an older machine. The new ones have to pieces joined by a piece that wraps all the way around.

 

[dfkrug]

The pic with the bent metal is an older machine. The new ones have to pieces joined by a piece that wraps all the way around.

Wow, that is an impressive bend, And needs more bracing. Looks like it is made of the same 12mm mild steel plate that was used in the floor of the house.

I may have to start a thread on Repairing Small Chinese Excavators.

 

[jodieadair]

Wow, that is an impressive bend, And needs more bracing. Looks like it is made of the same 12mm mild steel plate that was used in the floor of the house.

I may have to start a thread on Repairing Small Chinese Excavators.

That would be great, I very much appreciate your insight. You could start right away, tonight even.

 

[oldrustysteel]

I've noticed that the newer machine have a redesigned sprocket section, it apperas to be much more robust. See attached pics. Do you think it would still be wise to add bracing accross the rear to keep the spacing.

Definitely. I find its much easier to weld in reinforcements when something is straight, before it gets bent and twisted. Often its impossible for me to get something back to perfect. Besides, most people want to add weight to their machine, so I can add it 1lb at a time!!

 

[Carl_NH]

The MachPro Mini Ex have a bar welded between the drive motors. This seems like a simple add on and could add weight box on the top too. See Image # 15 https://www.rbauction.com/idp/2023-...14360904&id=ci&auction=los-angeles-ca-2024264

 

[dfkrug]

The MachPro Mini Ex have a bar welded between the drive motors.

Good find. Thanks for posting.

I have been working on tying my rear hose protection into a lower plate. I was going to use some stainless steel plate, but now I think I will go with a thicker bar like in the photo. Esp after seeing pix of that bent frame.

I wonder why the MachPro folks did not do anything about protecting the hoses.

 

[dfkrug]

I also really like the improved blade cylinder with hardlines to protect the vulnerable hoses and fittings. Also note the tie-down holes in the blade. Nice.

Tiedowns in the rear sure would be nice, too.

 

[D'oh]

The MachPro Mini Ex have a bar welded between the drive motors. This seems like a simple add on and could add weight box on the top too. See Image # 15 https://www.rbauction.com/idp/2023-...14360904&id=ci&auction=los-angeles-ca-2024264

I also like the Idea of Pin with Lynch Pins, for the Thumb!

 

[jodieadair]

The MachPro Mini Ex have a bar welded between the drive motors. This seems like a simple add on and could add weight box on the top too. See Image # 15 https://www.rbauction.com/idp/2023-...14360904&id=ci&auction=los-angeles-ca-2024264

Good catch, that's exactly what I was thinking.

 

[jaylast]

Connecting the frame tails / motors with steel member seems like an ok balance of strength/ease/aesthetics/function.

I opted not to do that yet. Aesthetics
jodieadiar: thanks for the pic of yours - that setup is substantially more stout with the 3 dimensional shape, I wouldn't expect any issues.
Wow I wonder the age/make of the bent one in your other pic- really obviously a poor design (without some decent gusseting)

Has anyone here needed any undercarriage parts

I don't think so. I'm thinking the greater average of machines will last with minimal repair/replacement for the first 2k or so hours. Shouldn't be difficult to source the bearings and generic stuff, and repair the rest.
My issue with 'agt' - I've not heard of direct contact/avenue to manu for parts?!? So yes a pain then to source drive sprocket (or more likely needed first - drive motor(s)). Does seem like they are working on NA dealer networks though - so perhaps a dealer could source (with their cut of course . . .)

The manu of mine seems to have everything available, to a point. For instance she got a little perturbed when I insisted they should source/sell cylinder rebuild 'kits' from their cylinder provider.
She can sell whatever cylinders you want but can't provided parts or even parts lists. Cylinders of this size not difficult to rebuild at all - . . . . with the exception of somehow finding the proper parts.

 

[jodieadair]

Connecting the frame tails / motors with steel member seems like an ok balance of strength/ease/aesthetics/function.

I opted not to do that yet. Aesthetics
jodieadiar: thanks for the pic of yours - that setup is substantially more stout with the 3 dimensional shape, I wouldn't expect any issues.
Wow I wonder the age/make of the bent one in your other pic- really obviously a poor design (without some decent gusseting)


I don't think so. I'm thinking the greater average of machines will last with minimal repair/replacement for the first 2k or so hours. Shouldn't be difficult to source the bearings and generic stuff, and repair the rest.
My issue with 'agt' - I've not heard of direct contact/avenue to manu for parts?!? So yes a pain then to source drive sprocket (or more likely needed first - drive motor(s)). Does seem like they are working on NA dealer networks though - so perhaps a dealer could source (with their cut of course . . .)

The manu of mine seems to have everything available, to a point. For instance she got a little perturbed when I insisted they should source/sell cylinder rebuild 'kits' from their cylinder provider.
She can sell whatever cylinders you want but can't provided parts or even parts lists. Cylinders of this size not difficult to rebuild at all - . . . . with the exception of somehow finding the proper parts.

They are still selling the machines with the old sprocket design, if you look at pictures of the ones listed online maybe 1/4 - 1/2 of of them still have it. The man bought my machine from said he couldn't find certain parts either and he is from China living in Tennessee. He said he just keeps a spare parts machine for his customers. Maybe when these machines start getting damaged, heavily used and listed for sale we can source parts from older machines. The drive motors on mine are BMK6-315 and I get several options when searching that one, I assume they will work but I may be wrong.