Cat 777D Mining Truck
 

I have decided not to build the Marion dragline for several reasons but I am going back to the Cat 777D mining truck. From what I have heard this is the perfect size truck to be loaded by the Marion shovel like I have built. I am spending some time to see if I can make some tires which will be the deciding factor on this build. If I can make an acceptable tire then I will go forward with the truck. I am also making a rough wood mock-up of the truck to see if all the components will fit inside. I think my scale (1/30) will cause some problems because the truck is small and the way these trucks are designed there is not much room for motors, batteries, ESC's, etc. but I have to stay with this scale to match my shovel. I have started the master part for the tire and I am waiting on some small end mills to cut the tread pattern. Here is what I have so far -
http://i305.photobucket.com/albums/n...k/100_1133.jpg

http://i305.photobucket.com/albums/n...k/100_1134.jpg

Re: Cat 777D Mining Truck
 

I will post more pictures as I go. Making the master will be the hard part for me. I don't think the molds and tires will be to hard to build. Time will tell.

Re: Cat 777D Mining Truck
 

Great idea Tom, We don't have enough rigid frame rock trucks. Hope you can fit all the components in. Maybe hide some parts in the bottom of the dump body like the batteries and have a removable cover to access them.

Re: Cat 777D Mining Truck
 

3 3/8's = 85mm, tam trk tires are 83mm.

To propel the haul trk and to save on space you could use gearhead motors directly on the wheels, just like my Stahl Volvo adt. That truck has plenty of power & good speed too... though I don't know exactly the rpm.

Re: Cat 777D Mining Truck
 

Looks like a good start for the build. Gearhead motors would save lots of space. If you need any ideas for what to use for the electronics, you might want to get with rc farm guy. Not sure if this is his name on this forum but he has r/c'ed lots of diecast vehicles. He has helped lots of people with their vehicles.

Re: Cat 777D Mining Truck
 

Lilgiantsjoe-the tires are actually 3-1/2" dia.x1-5/8" i.d. I could not find any this size so I thought I would see if I could make them. I am thinking about dual g.m.'s in the wheels but not sure if it will turn. I have no experience with mixing in the radios but thought that may have to be used for turning. May need some help on this when I get there. tc1cat-I am just starting and not sure about anything yet. I am not to good at engineering and design I just start building and go from there and sometimes that gets me in trouble but I hope it will all work out. I may ask for help as I go.

Re: Cat 777D Mining Truck
 

What did Sargent Gunny Highway say in Heartbreak Ridge? "Improvise Adapt and Overcome"

Re: Cat 777D Mining Truck
 

I got the tread pattern cut, now I have to slick it up and make the mold. I went with a simple design that I felt I could cut. I saw a tire similiar to this at 'machinery trader.com". Also some of the foreign sites that make tires have one close to this.-
http://i305.photobucket.com/albums/n...k/100_1138.jpg

http://i305.photobucket.com/albums/n...k/100_1140.jpg

http://i305.photobucket.com/albums/n...k/100_1141.jpg
It will take me awhile to get a good finish on this.

Re: Cat 777D Mining Truck
 

WoW that's really nice. How did you mill the slots? Do you have a small CNC mill Tom?

Re: Cat 777D Mining Truck
 

Looks great. Are you doing a silicone overmold of the master or something different?

Re: Cat 777D Mining Truck
 

Thanks steve and pugs-steve, no I do not have a cnc mill.(wouldn't know how to use it if I did). Did it all manually on my ole smithy. Took lots of set-ups and lots of time but I have patience when messing with things like this.
Pugs-I hope to use a two-piece flexible mold. I don't think the parts would release from a rigid mold without having lots of mold segments which would take a long time to make.

Re: Cat 777D Mining Truck
 

Your "old smithy"....Shopsmith?

Re: Cat 777D Mining Truck
 

Done on a manual 3in1 machine? I'm impressed.

Re: Cat 777D Mining Truck
 

Snochaser-it's a "SMITHY" brand (chinese made) 3 in 1 machine. pugs-when you don't have money you figure out ways to do things.

Re: Cat 777D Mining Truck
 

Nice job!!!!!! if those were a 7 by 25/8 or 3 i would order 4 i have no paitents for makin my own tires nice job really

Re: Cat 777D Mining Truck
 

WOW, those tires look great, Tom. How did you do your set up on them, did you make a jig or what?

Re: Cat 777D Mining Truck
 

Thanks joe- no jig, just slow and easy, 1 set-up, then 30 cuts then on & on. The 1st. set-up was just a straight in cut. Then I had to bolt a plate to my rotary table so I could mount it on an angle on the mill table. Then I made the 2nd. cut at an angle toward the center of the tire. The side cut was an easy cut but a tough set-up. I had to mount the rotary table tilted up on an angle. I had an old adj. angle vice under my work bench gathering dust that I hadn't used in years. I dug it out and realized if I could mount it to the mill table it would work. So I put a plate on it and mounted it. Then I put the rotary table in the vice and raised it to a 40 deg. angle and made the side cut. Isn't it amazing what we will do to work on our toys!!

Re: Cat 777D Mining Truck
 

Tom, thats an outstanding plug you made there. I have no idea what a smithy, a 3-n-1 or any of that technical talk.........but that looks good.

Re: Cat 777D Mining Truck
 

Rod a Smithy 3 in 1 is a lathe mill and drill all in one. Ed

Re: Cat 777D Mining Truck
 

Thanks a lot sand craft transport & rob-all this talk about machinery doesn't mean much though, all that matters is what the results are. I have seen some great builds that the only thing used were hand tools. I don't know what tools you use rob but those pieces you made are amazing!!

Re: Cat 777D Mining Truck
 

That's a great looking tire plug you made. Well done! I look forward to seeing the mold and tires it produces.

Re: Cat 777D Mining Truck
 

won't the lugs be stickin out ????or is that used to make the mold and then the casted tire??

Re: Cat 777D Mining Truck
 

TD9-this part will be used to make a two-piece flexible mold. Then the liquid rubber for the tire will be poured into the mold. Let it cure then hopefully I will have a tire.

Re: Cat 777D Mining Truck
 

Do you have to coat the master with varnish like they do with sand casting? That would aid in releasing it from the rubber.

Re: Cat 777D Mining Truck
 

ahhhhh now i get it lol sorry i just didn't grasp the whole concept but now i do i wish i could make a solid mold so i can use it quite a few times like at a tire plant or something there is too much of a process for me to make tires i think unless i can buy solid rubber lol

Re: Cat 777D Mining Truck
 

Yes steve, This is the hard part. Varnish will not work but I have to finish it really smooth so it will release. I wanted to use glass filled delrin for the plug because it machines easy and you can mold directly from it but a 3-1/2" pc. cost over $200 with shipping and I only need a 1-1/4" slice and I probably would never use the rest of it so I went with the mdf but finishing it will take a while.

Re: Cat 777D Mining Truck
 

TD9-it is a long and time consuming process but I didn't think I had any other options. I e-mailed a couple of the foreign sites and although they did not have exactly what I needed I was going to buy their tires anyway but I never even got a response from them. Not sure how to deal with them maybe it has to be in their language, not sure?

Re: Cat 777D Mining Truck
 

do you need some delrin i shere i got some liking around at the shop for you if all you need is a 1 1/2 pice think it 4" but that onlu take seconds to make it 3 1/2 lol let me know we got some scrap think there is some 6" around too

Re: Cat 777D Mining Truck
 

Mog-thanks-maybe I should have ask around before I started. I am too far along now to start over but if this doesn't work I may get back to you. I am waiting for the silicone & rubber to make the molds and tires so I should know something in a couple of weeks.

Re: Cat 777D Mining Truck
 

Great looking tyres, will follow progress closely. To find tyres that matches are a very hard part, Have had som thoughts of building a Pete with lowboy to transport my D8, but then it is the tyre problem again.
I you find a easy way of making those you will solve a lot of problems for us others.
Dan

Re: Cat 777D Mining Truck
 

D8R-thanks a lot-I agree tires can be a huge problem especially when you are not building by the common scales. I did not want to make my own tires but I felt like I had no other options. This is not an easy solution but there is not a lot of work involved just a lot of time. For me making the master part was the hardest job. The mold and tires just require some time & patience. A machinist would probably make the master part from aluminum and you could spray the release directly on that and make the molds. I spent several hours with the finish on the wood part I made so the silicone will release from it. Hopefully in a few days I can see the results of my work.

Re: Cat 777D Mining Truck
 

Hi tom ..Not sure how far along you are with your tires but i did find this site with supplies and alot of free intresting how -to vids ..Any chance you could give us a bit of a tututial on how you are going about it...Cheers Lou

http://www.freemansupply.com/video.htm

Re: Cat 777D Mining Truck
 

T-n-T Lou-thanks for the link but I already have my supplies. I have the molds started and I am taking pictures as I go along so maybe I can do a how-to if everything works out okay.

Re: Cat 777D Mining Truck
 

Okay fellas, I have a tire! I will try to show how I did this. First step-I bedded the master part 1/2" deep in modeling clay. I put 4-3/8" steel balls in the corners and sprayed in the release wax.
http://i305.photobucket.com/albums/n...k/100_1146.jpg
Then I poured the top half of the mold-
http://i305.photobucket.com/albums/n...k/100_1156.jpg
After this cured for 16 hrs. I turned it over and removed the modeling clay and the steel balls and put the stems on for fill holes and air vents and sprayed the release wax on this surface.
http://i305.photobucket.com/albums/n...k/100_1150.jpg
I then poured the other half of the mold.

Re: Cat 777D Mining Truck
 

Aftter 16 more hrs. of cure time I separated the mold halves and this is how it looked-
http://i305.photobucket.com/albums/n...k/100_1151.jpg
This is the molds ready for pouring the tires-
http://i305.photobucket.com/albums/n...k/100_1154.jpg
I sprayed release wax on the molds and poured the black rubber mixture in the molds. To speed up this process I filled the bottom half about 2/3 full before closing the molds-
http://i305.photobucket.com/albums/n...k/100_1155.jpg
I had the molds on a perfectly level table to pour in the remaining rubber. I feel this is an important step to be sure the mold is full and to release all air. If air gets trapped in the mold the tire will be flawed.

Re: Cat 777D Mining Truck
 

After an overnight cure I separated the molds and this is the first tire right out of the mold-
http://i305.photobucket.com/albums/n...k/100_1159.jpg
Another-
http://i305.photobucket.com/albums/n...k/100_1161.jpg
I have these stems on the side of the tire from the pour holes and air vents but I can grind these off and turn this to the inside and I don't think it will be a problem.
http://i305.photobucket.com/albums/n...k/100_1160.jpg
Using this process I don't see any way to avoid this and I have a few tiny air bubbles on the fill side but I believe I can rig a shaker on the table and possibly solve this. I am happy with the results but will try to improve on the remaining tires. If anyone has any questions I will be glad to answer them.

Re: Cat 777D Mining Truck
 

Interesting! Thanks for sharing!

kerst

Re: Cat 777D Mining Truck
 

WOW that is really nice. I think if you had a small autoclave that remedy the air bubbles. Can you put a ruler next to it for size?

Re: Cat 777D Mining Truck
 

Modelman, Those tires are looking good, I use a vacuum pump from Harbor Frieght and a garage sale pressure cooker as a vacuum chamber for moisture removal from Powder Coating powder, my thought is that would remove the air bubbles from the rubber. So far I haven't seen any problem with this lash-up. Fred

Re: Cat 777D Mining Truck
 

The urethane stuff I mold in my shop has do be "degassed", once mixed I place it in a vaccum chamber (with clear top) and pull a vac with a AC vac pump until it boils out. Then when molded you minimize the air bubbles such as you have in a simple hand poured mold.

The vac chamber I have is just a piece of 8 or 10" pipe with a bottom welded on, top machined flat and a piece of 1/2" lexan for a top sheet. Port in side for vac line from pump.

The tires came out very nice.