First Tamiya truck build, MACK Dump truck 6x6

[RCP57]

Totally awesome! Great work!! More pictures please.

[scottyk]

Wow that link totally worked for me! but that doesnt mean everyone that visits the page will install that patch to see them. I really really dont want to upload all my pictures to a different server. but, in the interest of being a good sport and mainly the interest of shared knowledge between all of us I better just get started making a folder of all my project pictures, in hopes everyone else will do the same. Its a small community and if we all stop sharing experiences because of some inconveniences that would be a shame.

[scottyk]

Ok, sorry about all the junk posts guys. Lets try some Flickr uploads here.

20170326_140310 by Scott Kositzky, on Flickr
20170325_151141 by Scott Kositzky, on Flickr
20170325_151144 by Scott Kositzky, on Flickr
20170325_155251 by Scott Kositzky, on Flickr
20170325_161953 by Scott Kositzky, on Flickr
20170325_164925 by Scott Kositzky, on Flickr
20170913_192954 by Scott Kositzky, on Flickr
20170921_000050 by Scott Kositzky, on Flickr
20170921_000058 by Scott Kositzky, on Flickr

[skeeter]

Nice rims! I believe that's the FIRST time I've seen them style rims for 1/16 semi trucks. I see a LOT of them on the 1:1 container trailers near the port of Tacoma, as well as the port of Seattle.

[scottyk]

For the detail hungry guys, if you look close the picture of the cast aluminum tipper bottom sitting next to its pattern you can see the amount of shrinkage that occurs with casting! its is very noticeable in a casting this long, but it also important with the wheels. I had many experiments in scaling and revisions to accurately cast the drive hex and bearing bores. I know it would be easy enough to machine the bearing bores but with the accuracy of investment casting you shouldnt HAVE to and I can now push the bearing in by hand with a good fit into the cast hole with minimal hand finishing. but I think I have a great model to use now and can start really knocking out some wheels!

I have ordered a automated 3d print smoothing machine in a attempt to get a better surface finish. So hopefully soon I will have more updates for you guys with better parts, and assembled wheels on the truck.

As for the tipper, I have some engineering to do on that guy, it is a heavy box! I am going to remake the patterns for thinner walls and probably shorter walls altogether because I feel this would make the truck top heavy the way it is. but for now I will finish this heavy box and figure out a tipping mechanism probably similar to RCP's setup with a threaded rod on the box.

[skeeter]

Why buy a smoothing machine? You can save $ & just do an acetone bath.

[skeeter]

Will you be offering them wheels fir sale?

[scottyk]

I am using a filament from overseas designed for investment casting which doesnt react to acetone like ABS does. I have used PLA before too and that also doesnt react to acetone.

This material dissolves in isopropyl alcohol which is waay better to work with than acetone. and the machine is just to make things easier on me, it makes a nice fog and rotates the part at the same time so I dont have to babysit the whole time.

In the grand scheme of things, its not too difficult to clean up the raw casting the way they are, but what fun would it be if I wasnt trying to make it better all the time. and this might lend itself well toward future projects if I make sand casting patterns out of the material I can smooth those out faster. and it also makes them water tight! which is a plus in investment casting.

[skeeter]

Originally Posted by scottyk

I am using a filament from overseas designed for investment casting which doesnt react to acetone like ABS does. I have used PLA before too and that also doesnt react to acetone.

This material dissolves in isopropyl alcohol which is waay better to work with than acetone. and the machine is just to make things easier on me, it makes a nice fog and rotates the part at the same time so I dont have to babysit the whole time.

In the grand scheme of things, its not too difficult to clean up the raw casting the way they are, but what fun would it be if I wasnt trying to make it better all the time. and this might lend itself well toward future projects if I make sand casting patterns out of the material I can smooth those out faster. and it also makes them water tight! which is a plus in investment casting.

Thanks for the info. I WASN'T aware that PLA won't
react to acetone bath. I'm glad I read that, before I tried doing it!

Yes, workingn with alcohol is much gooder then acetone!

There's ALWAYS fun times trying to improve upon our projects!

[frizzen]

Wow, that dump bed could take some abuse, and you shouldn't have to add any weight for traction ever.

The rims look great! Can you print the sprue like that, or is that print first then assemble?

[scottyk]

Originally Posted by frizzen

Wow, that dump bed could take some abuse, and you shouldn't have to add any weight for traction ever.

The rims look great! Can you print the sprue like that, or is that print first then assemble?

Sorry I misunderstood the question, I print the wheels separate from the sprue and then melt it together. IT would take alot of support material and time to print them as 1 big piece. There is probably about 70 hours of printing right now that goes into a full set, and I bet it would be double that if it was printed as 1 piece.

[scottyk]

That sprue is a 3d printed part actually, I designed it specifically for these wheels. Alot quicker to sprue them up that way when compared to using wax, they are pinned on one side and a hole on the other so I can stack as many as I want to. I also have a huge 6" diameter flask I am hoping I can fill up with a whole bunch of wheels and centers and lug nuts.

yes Im hoping I can offer the wheels for sale. I would like to have some more confidence in my castings before doing so, and I think alot of people would like to see these cast in brass for extra weight/traction. Which should not be a problem, just more money for material.

I have no idea what the cost would be on a set tho. I'd have to see how long it takes to even make a full set and if I would be cleaning them up and machining, or just selling the partially machined castings.

[scottyk]

Little update with the dump truck. I ended up purchasing a RCP dump bed for the old Mack. This cast bed is just plain TOO HEAVY and the weight is up high making it a losing battle. The long thin cross sections coupled with thick sections would create a difficult scenario to cast consistently. AND since I probably only make 1 or 2 of these things I decided it wasnt worth the time and effort re-tooling the patterns, to just buy Reg's product and be done with it. He has a awesome product and I already have it installed and working, what a great piece it is! thank you Reg.

I have made a little progress with the wheel castings, fueled by my motivation with completing the rest of the truck, I have a new batch sprued up and ready for the casting process, I plan on using silicone broze for the wheel centers to add weight down low, paint the centers, and using aluminum for the outside portion of the wheel so I can polish it like the real truck wheels.

I will try and get some updated pictures added to the forum, it is now painted and working!

[scottyk]

Here is a link to the post I made on the RC trucks and construction FB page.

https://www.facebook.com/groups/rctr...2%3A%22O%22%7D

[skeeter]

That thing looks AMAZING! Very smooth, bright, & shiney too.

[Microtrucker]

That thing is awesome man