1/14 CAT 390D LME
 

Hi Guys, I have recently Started building an all aluminum 1/14 scale 390D LME. Progress will be slow as I am making everything on a manual mill and lathe and this will be the first time I have ever used a mill or lathe. -Jeff


http://i784.photobucket.com/albums/yy130/jp7986/01.jpg

Prototype for the track pads. Still needs some work.
http://i784.photobucket.com/albums/yy130/jp7986/473.jpg
http://i784.photobucket.com/albums/y...3f228067_k.jpg

Drive line parts so far.
http://i784.photobucket.com/albums/yy130/jp7986/477.jpg
Roller cut from 7/8 rod. Still need to cut 17 more.
http://i784.photobucket.com/albums/yy130/jp7986/475.jpg

Was going to make the drive hub 1 piece but I could not find anyway to turn a 3inch dia. rod with my micro lathe. Seems all the chucks only hold 2.4 inchs or so. Anyway I will be makeing it out of three pieces.

http://i784.photobucket.com/albums/yy130/jp7986/478.jpg

Re: 1/14 CAT 390D LME
 

Undercarriage so far.
http://i784.photobucket.com/albums/yy130/jp7986/482.jpg

Re: 1/14 CAT 390D LME
 

Wow looks like a great start so far! You'll be a master at the mill and lathe by the time your done with with build. Keep up the great work

Re: 1/14 CAT 390D LME
 

Nice to see someone building 390. When I started building CAT 374 my other choice was 390, but It's so big in 1:14 scale that I end up doing slightly smaller 374.

Re: 1/14 CAT 390D LME
 

I started designing 390 just few weeks ago. It will be interesting to see what you come up to and also get some ideas from you. Are you using any CAD system for help? What mill/lathe do you have?

Post some pics of machining next time too!

Good luck!

Re: 1/14 CAT 390D LME
 

Another nice bucket build to follow, keep up the good work!

Re: 1/14 CAT 390D LME
 

Thanks guys.

My first choice was going to be the 374 but just before I was going to start my plans CCM just released their 1/50 390D LME model so I went with that instead.

No cad just good old handwritten blueprints and all the dimensions I am taking from the CCM 390D LME. Which not everything is perfectly scale on the model. For example the bottom roller I machined already. Turns out is not wide enough for the tracks on the model. I'm using a Taig mill and a micromark micro lathe 6X10. I'll be sure to post some machining pics later. I plan on making everything myself as much as I can. Hydraulics and all.


Indeed I hope to make myself a nice ME bucket like Ari's 374D. Can't promise it will be as nice as his though.

Re: 1/14 CAT 390D LME
 

Start of the bolt pattern. First time using a rotary table. Didn't know till half way through I was .010 off center. Its barely noticeable. I'm not liking this latest version of photobucket at all.
http://i784.photobucket.com/albums/y...ps2a5208bb.jpg

Re: 1/14 CAT 390D LME
 

Second bolt pattern. Now this one I was dead on for sure this time and it came out perfect.

http://i784.photobucket.com/albums/y...ps373430cc.jpg

44 holes drilled and tapped. Plus 24 teeth cut. I will eventually switch the screws over to hex head but for now cheap socket head screws will do.

http://i784.photobucket.com/albums/y...ps3c8beb37.jpg

Re: 1/14 CAT 390D LME
 

First attempt at making a 2 piece mold for the track pad and link bolted together out of a plaster cast. Since I don't have a cnc machine.

I was not sure if it was going to work and it didn't. It failed and cracked. The plaster it still slightly pliable after it sets(30 minutes or so) so I thought I might be able to slide it out ok. Even if I had added more water to soften it even more. The undercut on the track pad still would have deformed the mold. It was just a test anyway to see how the whole process goes.

The search is on for other methods. I'm considering lost wax, lost foam, or prototype metal mold casting. I will find a way to get this done. 102 track pads to go.

http://i784.photobucket.com/albums/y...ps2f3eab47.jpg

http://i784.photobucket.com/albums/y...psbb93cf7e.jpg

http://i784.photobucket.com/albums/y...psa10d0050.jpg
On the left side mold. On the bottom of the track pad is where the undercut is. That's where it cracked on me. Also I forgot to make a sprue or vent holes.

Re: 1/14 CAT 390D LME
 

Wow that final looks great! Can't wait to see the rest of it

Re: 1/14 CAT 390D LME
 

Dude, you used mill for the first time and made that nice sprocket? You are a serious talent!

From where do you get your tips on how to mill?


Keep it up, seems very promising :p

Re: 1/14 CAT 390D LME
 

Great project! It is going to be really interesting, especially the casting part.

Kerst

Re: 1/14 CAT 390D LME
 

i have a few links about making sand molds to do what you need ,let me know if you want them ,
but the best way is doing lost wax and using a wax tree and casting thirty or more at one time in a investment mold ,
and by the way plaster of paris will cause a exploration of hot metal because you can't bake all of the water out of it .

Re: 1/14 CAT 390D LME
 

Thanks Madda. It took me forever trying to get that thing done. Lots of head scratching and late nights watching you tube on machining. There's machining videos on there for everything it seems. That and trial and error got me through. I'll probably cast it like my tracks to make a second piece.

Thanks Kerst. Casting has been quite difficult but I think I might have figured it out.

Re: 1/14 CAT 390D LME
 

I would appreciate those links very much :) I sorta skipped over sand molds because I thought the undercut on the track pad would be impossible to mold. I've looked into the lost wax and everyone says its an expensive process with all the equipment needed. I only thought about taking that route as a last resort if all other methods failed. We'll see if it ends up that way. As far as plaster of paris, I didn't know about the water issue. Is there any way around it? I was going to fire it in my kiln to dry it. I would think 1832 degrees Fahrenheit would be enough to dry it completely. I haven't found a lot of info on casting metal into ceramics and what Ive found. The info on the slurry mixture they used for plaster is always different or not very in depth.

Re: 1/14 CAT 390D LME
 

http://i784.photobucket.com/albums/y...-50-33_382.jpg

http://i784.photobucket.com/albums/y...-35-42_863.jpg

http://i784.photobucket.com/albums/y...-11-02_524.jpg


My first negative silicone mold attempt that I'll use to make a positive silicone. Them I'll use it to make my negative plaster mold. In the final third picture, the mold came out quite well except for a few bubbles around the bolts. This was a result from most likely not vacuum degassing the silicone before I poured. I would have except I have yet to make a vacuum chamber and get myself a pump. Those are on the list next.

Re: 1/14 CAT 390D LME
 

http://i784.photobucket.com/albums/y...22-07-03_5.jpg
Second attempt was a failure again but I'm getting closer. Air bubbles all over and it cracked.


http://i784.photobucket.com/albums/y...-11-05_280.jpg
Third plaster mold attempt. Once again there were a few tiny bubbles in the silicone that can be seen as imperfections on the edge of the track pad.


http://i784.photobucket.com/albums/y...-06-44_796.jpg
Third time worked. Almost. Although it did not crack on me I still have a few air bubbles. Again I'm sure I can easily take care of those once I get my vacuum chamber built.

Re: 1/14 CAT 390D LME
 

So the plaster castings might be good for how many liquid metal pours? And what type of metal will you be using?

Re: 1/14 CAT 390D LME
 

10 to 15 pours per mold I am guessing. I was going to use aluminum A356 but I'm concerned about durability so I will be using Zinc Alloy 27. It is stronger and has a tensile strength of cast iron.

Re: 1/14 CAT 390D LME
 

Hey JW, have you seen myfordboys video's on youtube? http://www.youtube.com/watch?v=l638qR0Y6YE Hope you find them usefull!

Cheer's, Neil.

Re: 1/14 CAT 390D LME
 

Thanks Neil. His videos were some of the first I came across when I first looked into casting. Lots of cool videos on sand casting. I'll definitely use this method for many other parts I need to make.

I did first try this way for the tracks with a 2 part flask with greensand but quickly abandoned the sand casting and never poured the one mold I made. Its just not possible to do such an undercut part easily with this method that I see. That's why I just tried a track pad but this alone is also undercut for the leading and trailing edges to mesh with each other track pad. So it didn't work out. What I want to be able to do is cast a track pad and links together without having to bolt the two together or have to machine each piece even more. Even if there is a way to do sand casting with the whole piece. I still don't think I'll do it. Its still such a long process to do just one sand mold for one piece. It would take me weeks for a set. My goal is to be able to cast a complete set of tracks in one day.

Jeff

http://i784.photobucket.com/albums/y...-59-24_638.jpg

http://i784.photobucket.com/albums/y...-58-15_651.jpg

Re: 1/14 CAT 390D LME
 

I really hope you get a decent solution for home metal casting because I believe that many of us would then try it too and that would make builds even more awesome!

But why I really posted was that I read on a local 3D printing site that they offer making molds. Maybe you can find a solution from there?

Just wanted to help, maybe you already know that option.


Keep it up!

Re: 1/14 CAT 390D LME
 

Hey Jeff, thick and thin area's in a casting will alway's be a shrinkage problem. What I'm wondering is, can you cast the edge thick, and clean it up on a belt sander, to get the curved radius, on the leading and trailing edge? Just a brain cramp!

Cheer's, Neil.

Re: 1/14 CAT 390D LME
 

It would be awesome if I get this figured out because I would like to share it with everyone. I've been looking at all you guys build all these great builds for a while now and when ever someone comes down to making home made tracks. It easily drives anyone nuts with all the machining, drilling and tapping. I was going to do all of them with my mill but after making just one I was done. You know what I mean. Time for casting.

Yes I've been looking into 3D printers for a while. I hope to get one of my own someday. If you had one of those you could design anything and easily cast the parts in sand. You wouldn't even need a mill or a lathe :D 3D printers just print plastic so it would be good to make a master that's it. Low production parts could be sand cast and high production could be plaster cast.


I should be good with molds though as I am now able to cast a part in plaster with zero cracks and zero bubbles. It just needs to be fired in my kiln, add a sprue and vent hole.

Thanks
Jeff

Re: 1/14 CAT 390D LME
 

Ah yes the shrinkage problem :D I designed my track pad and links .015" per inch oversize. To account for the 3/16" shrinkage per 12 inches for aluminum that I was going to use. Now though I will be using zinc, its 5\16" per 12 inches. So its now undersized just a hair.

About casting the edge thicker I think it might work but now you have to make sure you sand each leading and trailing edge on all pads to match each other perfectly so they mesh. That would be a job for someone with a really good eye and steady hands.

Re: 1/14 CAT 390D LME
 

I did some research on the plaster of paris and its moisture content. The plaster is calcium sulfate hemihydrate(contains water). So yes molten metal plus water equals mold failure and or a steam explosion but only until it is heated above 392°F, it forms into anhydrite(does not contain water).


First plaster mold with no imperfections.
http://i784.photobucket.com/albums/y...-23-49_289.jpg

Re: 1/14 CAT 390D LME
 

Jw.-sounds like you are stuck on making metal tracks but I think your goal of a complete set of tracks in 1 day is unrealistic. Have you considered other options? I made rubber molds from silicone rubber and cast my track pads from epoxy. With rubber molds you can have undercuts and just peel the molds away from the part and the epoxy parts are plenty strong for a model. I cast the hinge pin holes into the parts at the perfect size but depending on your part you still may have to do machine work. This is the master part ready to mold-

http://i305.photobucket.com/albums/n...100_0055-2.jpg
This is the rubber mold-
http://i305.photobucket.com/albums/n...100_0138-1.jpg
Here is the track pads-
http://i305.photobucket.com/albums/n...n/100_0108.jpg
Track pads assembled-
http://i305.photobucket.com/albums/n...100_0126-1.jpg
Something to think about ????

Re: 1/14 CAT 390D LME
 

Thanks modelman! Casting the hinge pin holes is a brilliant idea. Saves so much more machining time. I will try to incorporate that in to my next molds. What's the strength of the epoxy your using? How are they holding up on your shovel?

I have considered using resin or plastic but I'm hoping to get the metal tracks going if I can. I have some hard urethane plastic that I will try out later. It has a tensile strength of 5,840 psi.

Thank you for the pictures.

Re: 1/14 CAT 390D LME
 

Jw.-I don't know the physical properties of the epoxy but you can check it out if your interested-
http://www.smooth-on.com/Model-Making/c1290/index.html
I bought all my products from them. Quick shipping and okay prices. The epoxy is plenty strong for my use. I cannot break the pads with my bare hands. This type of shovel doesn't crawl as much as an excavator or a dozer so I took that into consideration. It took me 3-4 days milling to make the master part from aluminun so machining 70-75 track pads was out of the picture and I can not do metal casting so the epoxy was the only option for me. I have not crawled the shovel in the dirt which is the true test for a model but I think it would do just fine. The way the tracks and sprockets are made I don't think dirt would bother it.