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MadInventor

Grapple Skidder scratch build

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Quick picture of the front drive shaft now in:

img33435_30102013162223_1.jpg

But the big news today is that the motor turned up :)

img33435_30102013162223_2.jpg

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I'll let the pictures speak for themselves, I've included the 540 as a comparison of size... B)

I'm planning to mount the motor in the centre of the 2 bulkheads it's sat on, but will cut out the bulkheads with a boring head to recess the motor further down closer to the front axle.

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Only 1 more part made since the last post, but I've now got it up on 4 wheels, woohoo. :) It's always nice when building something to actually get all the wheels on, as it gives an (very rough) idea of what the finished model is going to look like. Here's a couple of shots of it against the 6x6 to give an idea of size, and how the hinged chassis is going to work.

img33435_13102013132024_2.jpg

Awesome build so far. This is going to be cool!

Where did you get the mini wheels and tires that look like mini Jugg wheels with mini Clod tires?

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Awesome build so far. This is going to be cool!

Where did you get the mini wheels and tires that look like mini Jugg wheels with mini Clod tires?

If you mean the back wheels on the 6x6 they are TLT-1 Rockbuster wheels and tyres.

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Is that whimpering I hear from each of your axles?

Now we'll see how tough Traxxas really is (REVO diffs) .... ;)

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Oh poop that's one BIG motor . This will pull tree stumps never mind the odd fence post or log :lol:

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Never mind the motor, what ESC are you using to run that thing?

The motor is quite low current, being only 800KV, max current is 78A at 6S, so I should be fine with a 70A Ezrun speedo for the 3S I plan to use. Failing that, I also have a 120A Ezrun on the way.

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Started on the logging blade today.

The sheet metal is 1.5mm thick steel, box section is 12mm square, and the hinge pin is 8mm steel. I've designed it so I can bolt it all together, but I hope to get it all welded together at some point. The overall blade width is 295mm, and I plan to bend it across it's width in 2 places to give it the correct shape and some strength, so that will be fun :unsure:

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I'm going to fit a 5mm 'pin' through the main 8mm shaft at 90 degrees to it, with a captivated nut at the top. A motor will then rotate a threaded rod running through the nut to lift the blade up and down.

Update 03/11/2013:

Trial fitment of logging blade:

img33435_03112013180800_1.jpg

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img33435_03112013180800_3.jpg

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update 05/11/2013:

I've now got the recesses cut in the front bulkheads for the motor. There' still a little tinkering with them to do , but basically I've just got to make the retaining plate for the motor now and I can connect it up and give it a trial run.

img33435_30102013162223_5.jpg

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update 07/11/2013

Got the motor plate done for mounting the motor, and a TXT-1 drive shaft turned up in the post today from IBIFTKH (Thanks Rob :) ) :

img33435_07112013212301_1.jpg

Another pic of the motor, to give an idea of how much it's been recessed into the bulkheads.

img33435_07112013212301_2.jpg

I think it might a case of 2 steps and 1 back though, as I may need to remake the steel motor plate when I get around to ordering the motor that will operate the blade, as it's fitting in the gap between the motor bulkhead and the forward gearbox bulkhead, and I think motor plate may be in the way. I'll just have to wait and see. Also, where I removed the slider section from the drive shaft I had to replace it with a worn part, so that it just for a quick test run and sizing the fit of the drive shaft, I will need to make a fresh part to replace the worn one, and all these little jobs take time. Still, getting very close to being able to get it to move under it's own power now, even if I can't steer it. To give an idea of how strong the motor is, the wheels refuse to move when the model is dragged, when the motor is connected up. :)

I also need to get some shorter bolts for screwing the motor to the mount plate, as these are encountering resistance, and I don't want to tighten them into the motor in case I damage the rotor. It does say in the ad for the motor that the mounting hole depth is 8mm, and I know the bolts aren't that long, I'll have to check them with a depth gauge and try and figure out what's happening.

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Looking good! What's the "C" rating on your battery? One way to slow it down is change from a 3S battery to a 2S battery, and focus on higher "C" ratings for burst current... Hobbyking has some hard case LiPos with 6600mAh capacity and 65C continuous, 130C burst rating...

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Looking good! What's the "C" rating on your battery? One way to slow it down is change from a 3S battery to a 2S battery, and focus on higher "C" ratings for burst current... Hobbyking has some hard case LiPos with 6600mAh capacity and 65C continuous, 130C burst rating...

I don't really want to go with less voltage, as the motor is rated for 6S, and at 2S it might not work effectively. If I need to slow it down I will probably built a thin reduction box to bolt straight to the front of the motor and incorporate it into the motor mount, that way I can retain the power and increase the torque :), but I might get into space issues if I do that. For now I'm just trying to decide what motors / reduction boxes to buy to operate the steering and the blade, I'm thinking a 380 for the blade, geared to go from fully lowered to fully raised in about 5 seconds, and a 540 geared for 5 seconds lock to lock on the steering. If that's what I do, I will have 1.3Kg of motors in the front end. At least I won't have a problem with it pulling wheelies.......

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Just ordered a MFA919D111 motor for powering the blade up and down.

Hopefully it will 1) fit, 2), not move the blade too fast, and 3), be able to lift the front of the model off the ground with the blade. I've been spending the last couple of weeks making UJ components for operating the blade screwjack and the also some of the steering components.

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Just ordered a MFA919D111 motor for powering the blade up and down.

Hopefully it will 1) fit, 2), not move the blade too fast, and 3), be able to lift the front of the model off the ground with the blade. I've been spending the last couple of weeks making UJ components for operating the blade screwjack and the also some of the steering components.

This is going to be a bit of a beast Martin . Any thoughts as to the Cab design yet ?

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No thoughts on cab design yet, but it will probably be along the lines of thin aluminium plate with window cut outs, hopefully with a driver figure, again trying to mimic the john deere design. But at the moment my thoughts haven't extended beyond getting the steering and the blade working, and fitting in all the ESCs I'm going to need (Currently I'm thinking at least 4, throttle, steering, blade, and grapple raise/lower). I'm toying with the idea of using an old 3 step MSC for the blade raising and lowering though, to cut down on cost.

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No thoughts on cab design yet, but it will probably be along the lines of thin aluminium plate with window cut outs, hopefully with a driver figure, again trying to mimic the john deere design. But at the moment my thoughts haven't extended beyond getting the steering and the blade working, and fitting in all the ESCs I'm going to need (Currently I'm thinking at least 4, throttle, steering, blade, and grapple raise/lower). I'm toying with the idea of using an old 3 step MSC for the blade raising and lowering though, to cut down on cost.

if you need a MSC I'm fairly sure I have one in my spares . Its brand new but not packaged . Don't think I have a useable resistor though .

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Got some pictures of some more progress today. I ordered a MFA motor a couple of days ago for raising and lowering the log blade. Excellent service from them, and the motors were in my hand 2 days after ordering. I'm going to post a few pics of this one as one of the other members has an interest in possibly buying one or more. This one is an 11:1 ratio motor, fitted with a white end bell Johnson motor, very similar to the vintage ones but without the brass rivets on the end bell.

img33435_29112013202528_2.jpg

I've removed the red dust cover to show the gears, and I also removed the motor mount plate as I wasn't going to need it. Either the dust cover will be butchered to refit, or I will make another on the lathe. The main adapter plate to fit the reduction box to the motor appears to be die cast aluminium, with the reduction box being attached to that via 3 m2 bolts, screwed into brass inserts in the aluminium. the final drive output drive shaft runs in 2 bushes, 1 appears to be steel and the other bronze.

img33435_29112013202528_3.jpg

As this box is only 11:1 reduction, there are only 3 gears, and the intermediate one is steel (as are all the gears), and appears to run directly on its axle shaft without any kind of bushes.

img33435_29112013202528_4.jpg

The end plate has 3 holes drilled in it, presumably to fit other gears for different ratios. They are 2.5mm diameter, and the centre one proved ideal to put a m3 thread in to hold the motor steady in the model. Both plates are steel and 1.5mm thick.

img33435_29112013202528_5.jpg

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These are a couple of pictures showing the motor attached to one of the front bulkheads. I still have design issues to sort out before I get a permanent fit, but it's looking good so far. BTW, the brass UJ yokes are ones I made myself from scratch, they should be plenty strong enough for this application.

And here's a work in progress on one of the components for the steering:

img33435_29112013202528_1.jpg

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Based on the last photo, it looks like you have some sort of mill/drill/lathe all-in-one machine?

I'd really like to have a decent machine tool for cutting my own stuff, but I can't afford more than a square meter of floorspace or bench space for it...

EDIT: Question: Will you have limit switches to cut off the motor driving your jack screws?

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Based on the last photo, it looks like you have some sort of mill/drill/lathe all-in-one machine?

I'd really like to have a decent machine tool for cutting my own stuff, but I can't afford more than a square meter of floorspace or bench space for it...

EDIT: Question: Will you have limit switches to cut off the motor driving your jack screws?

The chuck in the picture is mounted on a rotary table mounted on my vertical milling machine (A Warco minor mill), but is easily detachable and then I can clamp work pieces direct to the mill or use vices, etc. I also have a small watchmatchers lathe from the 1950s that I sometimes use for lathe work, although I do have access to a better warco model.

My watchmakers lathe is only slightly larger than a laptop though, so I don't want to hear excuses about not enough space ;).

I'm not going to use limit switches, I'm just going to remove about 10mm of thread from each end of the screwthread. That way the drive screw will stay in the nut, but won't apply any force to it once the end of travel is reached. Reverse the direction and it will re-attach and start to work again. That's the plan anyway........

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Cheers Martin . The MFA looks like its what I need . It will be interesting to see if the other ratios have bearings or bushings . A pair of these has to be the easiest way to achieve 4wd on the Winnebago as they can bolt directly to the steel floor .

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Done a bit more over the weekend. Got a new motor mounting plate made that also fits in front of the blade motor for it's screws to recess into.

Also drilled the front bulkhead to fit the screwthread for the blade actuator through.

Soldered on a couple of motor wires for the motor.

Cut down the original red gearbox cover with a dremel and a Stanley blade.

Fitted it all back into the model.

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Edit 02/12/2013:

Had an unexpected leap in progress today and got the blade working. Still got to make some proper hinges for it, but at least it has the grunt to lift the model off it's wheels. 

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Been a while since I've posted on this, but I've been busy with the steering mechanism.

I've made a custom mechanism for operating the steering:

img33435_22122013153849_1.jpg

This is basically a slider with a left hand and right hand thread either side of the centre UJ. The screwthread on the left passes through a threaded hole in the front hinge bulkhead, and the left hand thread passes through a captivated nut in the rear hinge bulkhead. as the shaft is turned, the bukheads are pulled closer together, or pushed further apart.

img33435_22122013153849_2.jpg

The forward thread is threaded into the UJ, and held in place with a small grubscrew. The other thread is the left handed thread, and that was turned down on the lathe, and then pressed into the UJ with a bit of Loctite.

img33435_22122013153849_4.jpg

Here's a quick video of it working. I've used a power drill as a temporary power source for the steering, but the final idea is to drive it with a 50:1 MFA 540 motor running on 3S. This test was done with a 9V power drill. Tried it out on the patio to start with, and then in some long grass on a bank for a bit tougher test. I think it will be fine.

http://youtu.be/n_DUVJH6uaE

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Made good use of my xmas eve and made 2 steel blocks to support the blade pivot shaft. They're made from 6mm thick mild steel and are bolted to the underside of the chassis with 2 3mm bolts each.

img33435_25122013102842_1.jpg

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I also remade the brass pivot pin to be held on with a grub screw, to form around the pivot shaft slightly, and to be enclosed on the top end of it to give that a bit more strength.

Last job on this mechanism is to add a small bush to the pivot shaft somewhere to protrude through a hole in the bottom of the chassis to stop the pivot shaft floating left and right. It will be good to get this finished, then I can concentrate on finishing the blade off. I got it welded together, but found the blade was not on square. I had to hammer it flat and rebend it, but found it impossible to rebend once it was welded on and ended up splitting the metal. The upshot of that was that I had to cut the blade off the frame and bin it, so now I'm going to make a 3 piece blade and fit supports behind it to hold it all together, which is bound to be 2 or 3 days work on it's own. Once I get the blade finished I'm going to paint the blade, and then fit the motor for operating the steering. Once that is in I will be fitting the speedos to control the blade, steering, and main motor, so that I can drive it round in the garden.

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