My Mruder (bruder cat320 something look alike)

[cdm]

you are telling me. scaled it all properly for the veroma tracks and idlers.

here is a better idea of how it is going to sit. their sprocket uses 8mm bore but i will run 6mm like the idler and sleeve bearing it in the middle so it comes out to 8. then use the set screw to cap onto the 6mm shaft itself (my chain sprockets and hubs et all are 6mm so thats why going 8 would be harder than going from 6 to 8 on the sprocket itself). and a bunch of other boring stuff nobody cares about that i will be working around in the coming weeks.





14" long by 12" wide (outside to outside of tracks). I love oversized demolition bodies and that's what i am making.

[Lil Giants]

I like how you have it all closed up, keeps the foriegn material out of the track links.

[cdm]

as you can see i am short on rollers and stuff..... (ordered last night) but you get the idea. the bolts i'll have to cut because they are partially threaded and thats the only lenght that would work for me (45mm total). the plug fasteners which would be way better only come in imperial and i need metric. bugger that. no its not imperial i can adapt either. something stupid like 1/8 1/4 etc. nothing close to 4mm.

i could also go with 4mm shafting and collars but cutting those hardened shafts is a pita. and thats a lot of shafts! i'll try the bolts first. 8.8 steel is not too bad to cut actually.

i think i'll call it a day now.

[cdm]

I drank some coffee so decided to get some more done. I have been racking my head around the turntable for a while but i refuse to spend 400$ on the one from fumotec. besides, i cannot because my body upper plate is already drilled for the 3/8-1/2" bore .770 pattern. And that plate is drilled for the hydros and for the ballast. No go changing that really. Too much pain at this stage.

Anyhow my original turntable worked just fine, alas it was too tall and too long (and close to 5", which i cut down to 4 initially).

scouring my usual sources i found nothing better, thus it was time to just go for it.

Cut the height to 1/3 original and shortened it so it's a square. will machine finetune and smooth cuts tomorrow when it stops raining. Can't handle the metal dust indoors anymore. I will have to make new flush mounts and also load distributing mounts but thats to be expected. I tried to make it internal chain drive and get rid of the big gear on top, but couldn't fit the sprocket inside by 2mm! Still might do it with another mount hub.



next to a standard cap for size.



GROUND CLEARANCE! At this height i barely clear the top tracks so i can create a proper V pattern main section. Will take some creativity as it will house the 2 batteries, receiver, esc, worm gear drive, 2 track servos (i am going chain drive to track sprockets, 2:1 reduction for 400+ oz torque). Waiting on the worm motor from china; have all the rest.

[carp]

can you give a link or details on the worm drive from hong kong?

[cdm]

it's just a gearbox motor with a worm box instead of a planetary like what you generally see with these.

its nice because it isn't tall saving you space so you can have a flat undercarriage, also its worm gear so you dont need esc hold function to prevent turret from spinning or momentum from taking over.

its not nice because they are rather low torque compared to planetary rpm per rpm but with worm gears that's not really a big factor. you can't really stall them like you can with bevels/pinions

http://www.ebay.com/itm/12vdc-44rpm-...1185b9&vxp=mtr

I drew up the main plate today but didn't cut it. however once i overlaid it, it got me thinking. There is a new product out there like a 1" tall gearmotor that makes crazy torque @ 90rpm (70oz). I am going to fiddle with 4 of these along with 6t pinions.

Currently im running a single 77oz motor and am able to push dugged up earth sideways quite easy.... but i want more. so i figure i'll quadruple the power if this idea work, AND have even more space left over. if that doesn't work i'll go with the worm drive.

[cdm]

Decided to finish up my box today... Halfway in drilling the 2nd plate (out of 4) my extrator drill bit snaps.. the standard ones won't even dent the 2" deep plates...

So thats it for now.

I'll have them sloping when im done. Holes are recessed bored so i can use sturdy socket heads instead of the snapping pan heads.

[cdm]

box is done, tracks mounted.. all lines up perfect. i was measuring within .5mm accuracy. i figured any more and it would be an overkill. but i think i came to less than that at the end. and yes thats 3/8 alum plates. this width allows me to recess the screws properly.

still need to decide on the slant angle (you can see it drawn out roughly) and slot out the chain drive zones. more on those later.

also bought a tekin fxr pro to replace the chinese esc. it worked fine but for some reason it thinks anything over 80% is 100% rpm... so anyway, bought a new one. really not many options for brushed motors left out there it seems.

my new bearings for the turntable (abec5) and motors are due today.. assuming usps didnt forget to load them on the truck this morning. i may or may not make a reinforced turntable mount. Won't know until <-- these parts get here today and i get to measure it all with the pinions attached

[cdm]

Finished the turntable, mounted the motors. I feel i nailed the speed and torque this time around.

Added a reinforcement plate to eliminate any main floor twist during stress on the carriage

Redid the mount on the body section. I decided i needed to simplify the way to separate the 2 halves since it was a complete nightmare when i went to pull and reattach last night. Too much weight, too many hoses in the way etc. Now the whole gear and shaft pull out.

In my quest of making this serviceable, i noticed i will have to rip off vario and make a riser plate for the hydraulics on top of the floor. this way i can remove that instead of going under the body and unscrewing each component.

Still deciding on what method to use to make the hoses detachable from the block. those quick disconnects at 8 euro each i dont really trust. looks like leaks waiting to happen. might just go with the hose couplers; those dont have the sharp barbs so you can pull the hose off them easily.

ordered a few liters of oil and some other stuff the other day. atop of my tracks still being in the mail. german post is taking their time after breaking all records and getting here in 4 days the other time.

might also be a good time to order my premacon wide bucket. they say 2 weeks lead time but i dont know if i want to trust that.. also if anybody knows of better options let me know. im new to the whole contruction thing so my sources are limited.

now that i have it all apart i can do some painting on those parts i didnt get to before and then photos.

i started on the body panels but scrapped that as im still changing the height. i thought of making it out of metal, and even bought some parts but... i dont know. i'll probably just stick to styrene. i doubt i have the desire to drag that out any longer. already put my other toys on hold and with summer coming fast down here, i need my offroaders working.

[Lil Giants]

Make a one piece body like the Vario that easily lifted, I luv that feature! everything wide open in easy view to tinker.

You gotta get busy building a dumptrk fella!

[cdm]

Yep it will be one piece. Decided on that months ago. Which is why my upper section looks a bit weird still

Made the 2 platforms. One for the hydros and one for the electronics so they wont get soaked during future leaks.

Started working on the main boom details, namely the edge extrusions. Im adding those as beads just for looks and might make caps around the ram attachment points.

Meanwhile here is a little preview of what else i am doing. Wrapping it all with 1/8 plates. I tried to weld them last night but too much heat warped stuff up so i gave up on that. I'll just screw them and finish the joints/edges with epoxy. That's why i spent little time making neat joints. I am doing this just for fun so when you touch it, it's cold. when you crash it against something, it scratches realistically.




Cut and covered the undercarriage. Forgot to snap a pic of that, too lazy to go back down so next time.

Tracked up one side as well. 62 track pads per side... or 930mm. 1860mm in tracks altogether.

I am further adjusting the attachment between the 2 sections (body/undercarriage). I'll be pushing 40lbs now when done, vs my old 25lbs.

[cdm]

Made the huge mistake of ordering from onlinemetals.. a week to ship and they are drop shipping each piece on its own from all over the country. no tracking #s either. they just show at the door at random. never again. scammers.

on the flip side, 3rd order from mcmaster this week came in today so i could get some more work done..




Spent about 2 days making the boom pretty.... im also working on the stick but that is drying so no photos.

Still needs a few more coats (got too cold, had to stop painting), some decals and then a clearcoat just to seal decals in.



decided the track boogies looked too much like a ww1 tank so i added some metal to bulge the outside a bit.... still working on the final shape but it also allows me to hide the cross bolts...



progressing on building out the lower body. the screw holes i'll probably fill in when all is said and done. they aren't even since i don't want to risk seam splitting even though i drilled them out quite well.



the center carriage section... i tried to weld the 2 sides to the top but too much heat.. however i figured out how to attach them. i will show you later.

[cdm]

The only time you will see the turntable mounting gear and spurs.



i have so much clean up to do its not funny.. I should have really just scrapped the original parts and cut new ones. but too late for that, so i'll waste my time cleaning up and making covers..

[dabears]

I think its looking great so far!!! Awesome work

[cdm]

Well this was supposed to be a conversion.. hah!

Started building my own 10oz oil tank. The aim is to be able to dig with the machine tilted at 45d in any direction and not suck air in the pump port.

After wondering of a way to be able to connect an external tank to the pump, it was a no go. It is some weird square bevelled intake port and the return ports are some odd size too.. no go there.

Then i began playing with dubro tanks and the faucet and came up with a design that will keep the intake oiled at all angles i can throw at it.

After a few weeks the jb weld shows no reaction to the oil (its watered down toy hydro oil anyway, bet you it can live inside styrene as well - my next experiment!) so i can use that to weld and seal the new tank... I was thinking .090 plates but went with .040 to maximize capacity. It's plenty strong.

More later after i go to mcmaster tomorrow. I only got a few pieces cut tonight before i ran out of .040 sheeting. Speaking of that, finished the .125 encasting of the body and couterweight and began filling in the screw holes. Liking the way its coming out. A bit like a mining excavator but not quite. Also began cutting out the channels for the chain drives. got my chain resizer in as well.


Also building my own bucket. I have to start keeping costs down, this is out of control.

[cdm]

I am fitting in each plate and when i have it all lined up up i'll cut the teeth out of the front and then seam weld any gaps and grind smooth. Then i'll make and attach the side scoops and what have you not. Since i cannot extrude or bend metal, i am forced to piece it together. What a monumental pain drilling and tapping all that...... Although screwing them in allows me to remove each and adjust as needed. I thought about making the teeth removable but (like a tooth comb), i dont think i'll wear these out so scrapped that idea.

Width is 90mm inside and lenght.. not even sure. Probably scales up to 6cubic yards if we assume bruder went with the biggest 2.5cy bucket in their model.

Also worked some more on the cab. I should start on the rock guards soon and then i can paint and attach the glass.

ps. also remade the turntable motor mounts last night and cut out the chain holes through the chassis. mounting the servos will be a bit tricky since im blind holing it.. the bigger mounts wouldn't fit so i have to blind drill from the bottom so to speak.. there are ways around that but just fiddly.. so fiddly. i was actually off by 1 .2mm shim on the turntable motors for a perfect side to side symmetry. not bad for eyballing it! one side took 2 .2mm shims and the other 1 to get the same gear mesh.

[cdm]

the rough cut on the rake. going to finish it up tomorrow in the light. the teeth and the space in between them is slanted. i think i'll sharpen it all to a very child unfriendly degree.......


screwed in and welded the rest of the bucket, except this piece here. once i finish it up, its going in and getting seamed in. then attach my mount and call it a day. should do it tomorrow.

my latest batch of stuff from germany made it in today so yay. have to pick it up tomorrow.

deburred and resealed the control valve. 4mmX1mm seals on the plungers. if it still leaks... i'll be upset. but not too much, as i am thinking of upgrading to the 5 valve one.


ps. 3rd broken tap. 3mm is a nightmare to tap apparently due to size. at 8$ each it gets old fast. i am not getting any chip clearing really, so i have to back in and out little by little till its all threaded in. each time clean the debris out of the hole. if you go a hair too deep at once it snaps, usually on the counterspin.. blind holes, no issue with through holes.

also need to go pick up some more of that awesome hitachi orange from ace.

[cdm]

began making my own coupler.. I could just mount the bucket directly like last time but couplers are cool. I am mounting first, then trimming when needed and then trimming for looks. Enjoy the squareness until i get to that stage

Also redid the articulation links. I toyed with the idea of cutting a new H link out of solid metal, but im trying to keep weight down at this point. So i just used some standoffs to bolts between the 2 links and make a lightweight, althought not scale looking H link. It will do.




As you see i have to cut and regrind the stick yet again. needs more taken off the underside. Originally i didn't even have space for washers between the mount points. Which resulted in my paint getting all scratched up where there was contact. Now i am leaving enough space for at least 1mm shims on either side. Just little things here and there i suppose.

This brings me to adventures in metalworking. I am a total beginner in that but im figuring things out. Not a fan of the bucket screws but they will stay for strenght. I alumiwelded the gaps and what not between the pieces then grinded it down smooth. Put a coat of filler (still to sand that) over to cover any microcracks and prevent water from freezing in when i leave it outside.. Because it will happen.

Now alumiweld is something like solder mixed with liquid aluminum. It is weird, it doesn't behave like solder and is really made out as a filler and not as a structural weld due to its hit or miss bonding. You can bead it and parts will grip like crazy and other sections won't; it appears it is very sensitive to heat both on it and on the surface. Underheating or overheating will not let it stick properly or at all. That's why i am leaving the screws in. Anyhow, it is cheap compared to the specialty metal filled epoxies at 60$/oz. You can tap it even. It is just weird to apply and has selective adhesion (or very specific application needs which looking at the array of videos, nobody has quite figured out yet). For the price i am happy with it and it got me the rounded shape i wanted.

I dont know if i will add the side flaps on the bucket. I started putting in a little cuve and might just extend that. As i said, weight that far out is adding up. I still have to add the mounts to the bucket itself so more weight.

PS. i wanted to make a bucket, i may still get a premacon one. But unless you make it yourself, how will you learn right...

[doodlebug]

ps. 3rd broken tap. 3mm is a nightmare to tap apparently due to size. at 8$ each it gets old fast. i am not getting any chip clearing really, so i have to back in and out little by little till its all threaded in. each time clean the debris out of the hole. if you go a hair too deep at once it snaps, usually on the counterspin.. blind holes, no issue with through holes.
What size tap drill are you using? look at your chart, go for 80% or less thread's, to help prevent the tap's from binding and breaking. Hopefully the pro's will chime in on this!
Cheer's, Neil.

[cdm]

2.5mm which is what is recommended on the tap list.

used 2.7 as well but wasn't happy with the thread bite. it was certainly easier going tho