control valves and cyllinder bore for digger [Archive]

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cdm

11-26-2012, 05:34 AM

Time for my maiden post on here. let me give you some details:

take your basic bruder cat 320 toy since we all have one of these.

im building/converting it to a functional excavator. total weight will be 20-30 lbs incl the ballast i'll squeeze all over the body.

the boom has been extended 1.5" for the lower section and ~3" for the main section for imo more realistic reach. epoxy and metal internal construction so the arms are literally solid pieces. the total arm will weight ill estimate at 4-5lbs, maybe less. ill know by wednesday when im done putting it together.

That said,

Control valves

do i use a 3 spool (3 way) and use tsplitters for the dual main arm cyllinders so both work off one hydraulic channel.

or

do i use a 4 spool (4way) and control each cyllinder independently through yharnessing the servos for the tandem cyllinders.

which way is better to do it?

cyllinders

what bore size would you recommend? it must be 2.5mm ID hose size however (3mm nipple standard fitting). 5mm system i haven't located but it sounds expensive and custom order.

power and speed should be realistic. im not going to go dig up my yard but it needs to go through wet sand and loose wet soil/mud without breaking or choking up.

pump
the 350ml one from wedico/garden az dealer that comes with the "free" filter

or one of these

http://www.der-getriebedoktor.de/shop2/artikeldetails.php?aid=2701

honestly they look exactly the same? but the leimbach claims 380ml and 12bar at 12volts vs the wedico/noname one at 350ml 10 bar at 12v (which from what i gather should be adjustable on BOTH pumps via a screw from 10 to 16 bar anyway)

on a side note:

i've been swapping mail back and forth with vario about their m13/1 kit to find out what actually is part of it but the language barrier is IMMENSE and im getting frustrated. also they seem to not receive half the text i send. so still working on getting the component list in the m13/1 package for 1100euros and change they sell.

im hoping it includes the cyllinders. now if it does, would that package be worth it ( price is comparable to me getting each component separately). assuming me and the vario people can figure out a common language in the next 400-600 emails. :mad:

carp

11-26-2012, 10:42 AM

foub01

11-26-2012, 03:30 PM

This looks like its going to be good.definately agree with the 3 valves and a splitter for the two lifting rams.it gives an even preasure on each as they automatically ballance through the pipe system.do you have any pictures of the arm you hav strengthened as it sounds like a very good idea?

cdm

11-27-2012, 01:42 AM

Use 3 valves and a t splitter, not sure about the cylinder bore or pump someone else will though.

Vario m13/1 hydraulic kit http://www.vario-helicopter.biz/gb/product_info.php?products_id=100428

Some aluminium plates to mount the hydraulics
£13 filters you can get for £2
brushless outrunner you can get from hobby king for $30
longshaft pump 169euro you can get this as a complete belt drive for 390ish euro i think from fumotec but the flow will be to much for a small model i think
the valves you can get from fumotec also mine cost £327 for 4
hydraulic tank is an rc car fuel tank you could pick 1 up off ebay cheap

www.fumotec.de

here is the cylinders from vario http://www.vario-helicopter.biz/gb/product_info.php?products_id=100294
lot of money for cylinder that are to big for your model, once you find out what size you need just pick up some cheap pneumatic cylinders from ebay4

Thanks for the info carp. That picture saved me some aggravation pursuing this as Vario has stopped responding altogether. And i thought eastcoastvario was annoying to deal with when it came to helicopters. ugh . :rolleyes:

I have the cyllinders sourced; 69$ each and those things have been tested beyond any abuse i can ever dish at them (they are off the chinese earth digger). never heard bad things about them so i'll make the geometry work with the sizes they sell in (smallest 172mm).

Trying to get the valve blocks, fittings and pump stateside. I should have a confirmation of stock status on those tomorrow. Else its chancing it with germany again (6 weeks in, still waiting on things from there btw, not related to this build).

i got turntable, drive mechanics, metals etc shipping this week. but stuck with the hydraulics as of tonight. hopefully tomorrow brings good news. once i have all main things in i'll start a build thread. don't want to do that now as you can see how one missing thing can throw it all weeks off and it gets too drawn out.

This looks like its going to be good.definately agree with the 3 valves and a splitter for the two lifting rams.it gives an even preasure on each as they automatically ballance through the pipe system.do you have any pictures of the arm you hav strengthened as it sounds like a very good idea?

i normally dont do this as its offtopic but here

just to give you an idea, pretty simple really. i know most like to cut metal to shape and build an inside structure of the stock arms. but i despise working with metal so i opt to keep that to a minimum.

cut in a location where the curve of the boom is smallest, or wherever you want to really. its triangle like so it will shrink in both directions as you expand. but you have to keep it level on one side and just level out the other one afterwards. then frame it from the outside so it stays in place. you can bondene the bruder, just it doesn't hold too well, but strong enough for keeping it secure temporary

http://i.imgur.com/bfcYB.jpg

split it up and scratch the plastic deep and nice. then lay down plastic epoxy (i bought 200 packs of the ITW stuff, sold under many brands. yes 200. got a deal at 2$ per pack (retail 6) a while back) and it has never failed me where using styrene cannot work or where you have to bond plastic and metal together.

http://i.imgur.com/M4ZUJ.jpg

next get some threaded rod - i use m3 as i have 20ft of the stuff since i bought various types a while back testing what i wanted for another project. so i have spares to cut and destroy. cut it to lenght as needed and lay it down over the epoxy and joint. i use 3 rods per side, total of 6 per joint. epoxy over that.

http://i.imgur.com/Wqedk.jpg

then you go along the entire boom the same way, you epoxy to bottom so it bonds to the stock abs and then on top of that you can lay styrene rods or metal rods (depending your weight needs). i used styrene as filler since i dont want a super heavy boom. but you can go all out and use lead ballast if desired.. right. so once each half is filled up with epoxy and whatever other inert materials you have chosen, lay down another epoxy layer and stick the 2 halves together. then you pour epoxy over the steel rods in the joint just like you would do with concrete over rebar. then you get your dremel/grinder and begin to smooth off any really ugly deformations, like the molded fake cables bruder put. then you go from there and make it pretty or ugly as you desire. thats the tedious part... bondo. the better you grinder skills are the easier your final step will be; mine are rough, i like pain, i fix stuff afterwards.

http://i.imgur.com/lQ4aJ.jpg

then for the actual connecting points, i use the stock bruder holes. the truck is to make sure that channel is very well put on the inside with no air in the epoxy. or thats where you would put your styrine or metal bars even.

now get a 6mm/3 OD/id spacer, drill the hole in the arm with a bench press and hammer the shaft down into that. trim the edges before or after as desired. then use 3mm shaft to slide into that. and then you have your connections. the 3mm shaft spins inside the 6mm fitting and there you have it. with some good marine grease between the two, the joint should be as wear proof as anything you can buy from the big boys, if not better.

http://i.imgur.com/8KAf2.jpg

unfinished but you get the idea. i desided to make it pretty before i drilled. one of many layers to be sanded.

the stock bruder cyllinder mounts are there just for my reference. the actual ones ill cut out of aluminum channel. and screw it down to the boom.

Lil Giants

11-28-2012, 03:13 AM

The Vario hyd system is much too big for what you're doing. The pump is Jung @ 0,3ml/rev & with the bl motor & belt reduction Vario is using = 1.2L/min, 18 to 22mm bores for 150 to 200mm+ strokes, 2.5/4mm plumbing.

T fittings for the boom.

It's not Wedico hyds.. Klaus Leimbach & son supplied hyd pumps, valves & cyls for Stahl, then wdc & as always for everyone else who wants to custom build.

I would say 14 to 16mm bore would be plenty for what you're doing.

FWIW, communicating with german companies... no spelling mistakes, no lol text, no slang, no run-on sentences, use exact words and keep it brief. Chances are they are using a translater program to help them understand your script. Pepper them with analytic specifics & pricing combos, they'll likely get annoyed & won't respond.

cdm

11-28-2012, 11:52 AM

heh it was an experience. vario replied after all and sent me the link to the exact kit/page carp posted.

On the picture you can see what contains all the article no. M13/1.

Have a nice day!

i just about fell off my chair. their loss, moving on to the next supplier

gardentruckin never got back to me with if they have what i need in stock, so i assume they dont. they said they would; never did.

moving on to a yet another source

last night i took a leap of faith and shopped at der-getriebedoktor (should be the same as the fumotec store mentioned above) and they shipped the order this am, and refunded me the vat already. that was fast, under 8 hours from order to shipping.

I thought the pumps et al looked the same. What threw me off is that i've seen bunch of wedico diggers and they look like they have leimbach hydraulics in them (now that i looked at those closely). Is that something the end customer retrofits or does wedico use them in their kits/finished models? Granted there have been some complaints about wedico reliability so im confused on that part as i've heard nothing bad about leim.

I bought all Leimbach labelled gear, fittings, oil, valves, hose etc etc. i think i got all the things i need from there in one go.

ok back to me chopping on the turntable and boom while the goodies get here. Will start a proper thread once i make some more headway.

This is my first hydraulic build so let's see if i do anything stupid.

One last quick question, hitec or futaba servo spline and how much torque do the servos need to have for the valve block? i like digital with at least 100oz and have been throwing those in anything lately. but it might be overkill here?

Lil Giants

11-28-2012, 01:34 PM

cdm

11-28-2012, 03:52 PM

It's Leimbach hyds in all of wdc's models and it's a factory fit. I've had the odd defective pump or cyl... happens to everybody.. catch it right away & return it for new & they'll replace for free.

The servos for hyd valve are Futaba S3107... there might be others, but I don't know.

futaba micro 2 hole mount 2f spline

thanks! i see there is virtually no torque needed so anything with those specs will work

cdm

12-10-2012, 10:28 PM

I got a special delivery today

and i have 3 new questions:

1. voltage. 12v or 7-8v? what is stock for leimbach?

i was reading max rpm of the pump is 12k and even that is too high for prolonged use. im very disappointed at the stock motor that came attached. it has no bearings even. cheapest 2$ chinese 540 can they could couple :( Obviously i want to change that but need to figure rpm yield first.

2. the big set screws that sit against the valve actuators, from the top side. you remove those right? not supposed to use them to adjust or limit valve plunger movement? the valve block shipped with them screwed in somewhat but i've seen them taken out on wedicos altogether

3. idle position on the valve lobes/plungers. are they supposed to be opposite the valve pistons (the longer part; facing the wall) or should i center them onto the pistons and depress them? i could figure this part but i have limited parts and i dont want to blow something or dump all my fluid and then have to wait weeks for another order to come in.

Lil Giants

12-11-2012, 02:04 AM

1. 12v

The 12k rpm is probably what the brushless option might run @ on 12v. The brushed motor is about 6000rpm. The brushed motor is a Johnson.

The motor works fine, not overly efficient, but it'll likely outlast your model. I have one (motor & pump) with likely more than a thousand hrs on it.

2. hopefully you haven't touched the "big set screws" at all? They are there to keep the plunger centered till you get your servos in place. The exact placement may have been lost during shipment & if so? then the thumb screws come in handy to fine tune "center" & you can place your servo exactly. If the servo is a bit off when trying to screw to valve block, pull servo horn out of eccentric roller & rotate modified servo horn 180 degrees.

Obviously, but I'll say it anyway, you'll have to run your pump, make the oil flow to fine tune center on each valve. Once you're happy with the placement of your servo, remove the thumb screws from the valveblock.

And for 1st start up of your hyd system, run pump on 7.2v.. the slower speed will create less foam while you're filling your cyls & squeezing out the air. The reservior will need to be filled 3 -4 times while you're doing this, keep an eye on the oil level while you cycle each valve independantly.

3. not really sure what you're talking about.. it's the bearing'd roller that rides on the plunger rod.

cdm

12-11-2012, 04:11 AM

That clears up a lot! Allow me to elaborate

Of course i touched them, like an excited child on christmas morning. I played with them, then i removed them, removed the plunger to take a look etc. Oh well lol

The 3rd question was basically should i have the bearing roller press against the plunger rod and then set the servo to hold it @ neutral, or should i have the plunger face the opposite wall putting no pressure on the rod? the thumbscrews didn't make this clear, even when they were in. Shifted during transit more than likely as the package was a bit banged up.

Lil Giants

12-11-2012, 09:39 PM

ok. Now take a flat tip screwdriver & push the valve plunger rod down so you can push the eccentric roller all the way on. The bearing'd roller is atop the valve rod. The valve rod is spring loaded from the bottom only.

When it comes time to start your hyd system for the 1st time, then you will reset center with each valve & then use the thumbscrew to hold it in place, you can't guess it before hand.

Use a large enough flat tip screwdriver within the machined cross of the eccentric roller, doesn't matter which way you turn, turn far enough to get the cyl to go the other way & then back up some. That'll be center on the valve & when you set the thumbscrew to hold the valve till your servo is installed.