Metal Thickness?

   / Metal Thickness? #121  

kf4uda

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Maybe try some flow control valves on the main boom?
 
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BxB301

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I think too many GPM for the motor size....and just in general. Too jerky. And bogging and almost stalling the motor.

Without digging back through the thread, what pump did you use and whats the HP


I completely agree.
5.5HP paired to a two stage 3GPM/11GPM

What size pump are you thinking?
 
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BxB301

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Maybe try some flow control valves on the main boom?
I thought about that too - but also thought about just getting a smaller pump.
The flexing of the base has been fixed too, some front & rear supports just below the base. Its solid as a rock.
- however, the slamming down is still an issue. Pretty sure I can use this thing as a long splitter.
 
   / Metal Thickness? #124  

LD1

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2-stage and 11gpm is probably why that thing is jerky.

11GPM is ~60HP tractor flow rates. And a backhoe attachment on a 60HP tractor has alot bigger cylinders to fill.

I'd say you need a single stage pump And 3GPM is about the limit for a 5.5HP motor if you keep it under 2500PSI.

2.5GPM if you start pushing 3000PSI
 
   / Metal Thickness? #125  

Vigo327

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Gahh, impatience is forcing me to post before goong through that 1hr vid.. apologies in advance..

First off, CONGRATS and also thank you for following through. Makes the internet a better, more positive and aspirational place to see things like this get done.

Are you securing the pins against rotation? I saw the shaft collars and ive been using some of the same ones lately but you do need to weld one side of them to the frame so the collars cant rotate freely, and i found that even tightening them to the max of what i thought they could take (context: im ase master tech) they still allowed pins to shift/rotate in some cases. I implemented other ‘locating’ features in those cases (in addition to the collars).

Can you show the reinforcement you did on the frame?

I think adding a flow control valve with the current pump is probably slightly superior to ordering a smaller pump because you get to ‘try’ all the speeds vs best-guess ordering of a certain pump displacement. Also, you’re not committed because it’s adjustable. In theory if you turned the flow control down pretty far it would barely even change speeds when it shifted between high and low stages on the pump.

I have a 2stg pump and flow control waiting to be installed on my hydraulically driven Case garden tractor..

Any plans to improve ‘propulsion’, or are you still just working out the digging function?
 
   / Metal Thickness? #126  

4570Man

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2-stage and 11gpm is probably why that thing is jerky.

11GPM is ~60HP tractor flow rates. And a backhoe attachment on a 60HP tractor has alot bigger cylinders to fill.

I'd say you need a single stage pump And 3GPM is about the limit for a 5.5HP motor if you keep it under 2500PSI.

2.5GPM if you start pushing 3000PSI

The 2 stage pump is a big part of the problem. It doesn’t seem well matched to the motor either the way it’s always almost stalling. A single stage pump that’s 2-3 gpm would be a lot better. A lot of valves don’t work that smooth either. They’re more on or off and don’t have much precision control.
 
   / Metal Thickness? #127  

Vigo327

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The slew base is THE key reason that trading over a month of free time for the ~$1500 you saved over a pre-engineered HF digger, was worth it. It would be silly to back off of that at this point, in my opinion. What i think the digger needs is simply to be supported at a larger radius from the center. I don't remember what you said the dimensions of the 5/8" plate was, but whatever the shortest side of that is, a circle of perhaps 1" smaller diameter, will fit on that plate. That circle would be the contact points where your additional support will contact between the two plates. Those things should be adjustable and sacrificial but don't have to be complicated, just 4+ evenly spaced wheels or rollers of some kind. Kind of hard to cut pockets in the 5/8" plate at this point so they will probably protrude upward through the blue plate and be able to be preloaded down onto the 5/8" plate and take the brunt of the digging forces off the one big, hard to replace bearing which which still support radial loads and probably live forever doing that.

The over-fast cylinders is just too much hydraulic flow. I would suggest using an adjustable flow control valve vs changing the pump, because it removes the possibility of more 'error spending' on pump sizing, plus i think you will find it's just as bad to have the thing be too slow as too fast, so having the adjustability for ~$100 is the 'safe' option in my mind. The one downside is you still pump the full ~15gpm or whatever, and bypassing some of it means slightly worse fuel economy and heat buildup, but i doubt you care about the marginal fuel economy cost and your reservoir is so oversize that you have a lot of thermal mass in fluid, and surface area on the tank, to control heat. I would guess it will be a total non-issue. You can also adjust your 'transition' valve in the pump (forget the exact term, i think it's unloader valve) to transition to the low-flow pump section at like 300psi which is basically anything over just moving the empty boom up and down. So you could make it 'basically always 3gpm' with a pump adjustment if you wanted to.

As far as some functions seeming fast and some normal, again i think it's just an issue of radius. It looks like all your cylinders are the same size, which means at same engine rpm, each cylinder moves the same speed when you pull the lever. But, when you pull the boom lever you are swinging a 6ft stick, when you pull the dipper lever you are swinging a 3ft stick, and when you pull the bucket lever you are swinging a 1ft stick. The difference in 'tip speeds' might make you think that there is a difference in the controls, but there isn't. There are different motion ratios built into the geometry of the pin locations, but mostly i think it's the radii differences creating the perception of things being different that are really the same. What i mean by motion ratio is if you look at your bucket linkage, it is actually a 'reducer'. If the bucket cylinder extends by an inch, the pin at the bucket itself moves less than an inch. This is a force multiplier just like a gear ratio, giving better bucket breakout force. The boom cylinder, on the other hand, if you compare one inch of cylinder travel to what happens at the bucket end of things, it's a huge multiplier, probably 5-10x as much movement.
 
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   / Metal Thickness? #128  

LD1

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I have never tried it But I dont think adjustable flow restrictors work well with a 2-stage pump
 
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BxB301

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The slew base is THE key reason that trading over a month of free time for the ~$1500 you saved over a pre-engineered HF digger, was worth it. It would be silly to back off of that at this point, in my opinion.

Thank you for saying that, I completely agree with the slewing. I know beauty is in the eye of the beholder, but I really like the looks of this thing over the HF.

Having operated both a slewing machine, and a swing boom machine, I believe slewing is far superior.
With any project, there are some bugs to work out; this I normal. I'm not against throwing more money at it.
I see its digging potential, and I'm not ready to give up. The bearing is a problem. a 12" bearing can be had used on ebay right now for $1,000.
I looked into a matching pinion from Kaydon - its $1,200. So I'm going to keep what I have for now. However I sourced a 10" External Tooth Chinese replacement for $160 - but they sure don't give you any load rating, and they can't/wont give me the gear profile to source a pinion.

I added a section of square tubing to the front and back of the legs to support the machine (kinda like your suggestion of rollers) this made all the difference in the word. That base is solid, and I'm not over loading the bearing anymore.
I'm going to adjust it a little bit, and top it off with a section of UHMW plastic to help it slide better.
It can still slew, but depending on the boom/stick angle, only so well. I may need to upgrade the motor.
But anything better says "GPM: 20-30" I asked surplus center about what that means exactly, as they are small little motors, with SAE 6 ports, how could it expect 20GPM of flow?
They never got back to me.

The over-fast cylinders is just too much hydraulic flow. I would suggest using an adjustable flow control valve vs changing the pump, because it removes the possibility of more 'error spending' on pump sizing, plus i think you will find it's just as bad to have the thing be too slow as too fast, so having the adjustability for ~$100 is the 'safe' option in my mind.

I was going to do this, but I 100% don't trust that pump.
Today I purchased 1.93 GPM @ 2000 RPM pump to swap it out. (Surplus Center # 9-7786-B)

As far as some functions seeming fast and some normal, again i think it's just an issue of radius. It looks like all your cylinders are the same size, which means at same engine rpm, each cylinder moves the same speed when you pull the lever. But, when you pull the boom lever you are swinging a 6ft stick, when you pull the dipper lever you are swinging a 3ft stick, and when you pull the bucket lever you are swinging a 1ft stick. The difference in 'tip speeds' might make you think that there is a difference in the controls, but there isn't.

I went and played with it for awhile, and I too think that's what is going on.
Hopefully the smaller pump solves the speed issue.

Below, is plan B if I cant get this thing proper.
 

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   / Metal Thickness? #130  

Vigo327

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That looks like a former.. concrete buggy?! I love it!!

So glad to hear you’re sticking to the slew base. Even having to rotate with tracks between every scoop would SUCK. You wanna see a crazy swing boom idea, look at a Ditch Witch XT850! Crazy, not easy..

Will be interested to hear the results of the 2gpm pump. I would expext that to be on the slow side at anything less than full engine rpm. My preference would be for something that is a little fast at full rpm (but not crazy fast like your splitter pump!) and then rev down a little to suit. But its a balancing act because it takes X hp to make X psi at X gpm and i dont recall what your relief valve pressure is? Also, just out of curiosity, did the hydraulics ever stall the engine with the current pump? If you have a 3gpm high pressure stage on your current pump then the 2gpm pump would be proportionally slower than what that high pressure stage fees like right now. Cant wait for the updates!! 👍👍
 
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