g741.org

Hi Guys,

So in another thread we were discussing the lack of good brake drums available for our M37s. Seems there's none to be found and no one is repopping them. Switching over to disc brakes is the obvious solution, but for the purists who want to keep their truck as it was manufactured, that option doesn't work. Thinking about it a bit it seems this would be a perfect part for the 3-D printer laser sintering folks to be making. All that would be needed is an NOS drum that's been measured and checks out to be within spec, a laser scanner, and a 3-D laser sintering printer. Material choices are pretty much limitless, as just about every material we could want is available in powder for these printers. How cool would a nice set of titanium drums be? (kidding)

Do we have any forum members who work in the rapid prototyping business? Anybody know anybody who does. I know where to find an NOS drum....so that's not an issue. Let me know what you think.

regards,
bob

I know a couple of people and companies, Bob. Let me see if I can generate any interest.

Hi Bob,

I know that our Jim Lee make his four bladed drones on his own rapid prototype machine.

Bert

I sent photos and some nominal measurements to one of the major prototype houses that the company I work for uses. They are going to take the info to some of their bigger fab houses for preliminary evaluation. The fab houses are all ISO 9000 certified and routinely produce for the military, aerospace, and medical communities.

I'll let you know what I hear back from the prototype house. I've also got a few other places I can try if this one doesn't work out.

Nothing ventured; nothing gained. It's worth a try, and costs nothing to ask.

Awesome Storm. It's attitudes like yours that are going to keep this hobby alive. I'm going to hunt around a bit myself and see what I can find out in terms of making those drums.

thanks,
bob

That's a really neat idea. Although I have no idea on what material could be used.
My son built a small 3d printer but it uses different plastics. Comes on reels. He makes all kinds of brackets and things. really cool.

Hi F18,

Yeah, it's a pretty cool concept. The good news is the price to make parts that way is coming down every day..........so even if it's still too expensive right now, in a year or two it shouldn't be a problem. I'm not sure what a tolerable price for new drums would be, so I guess we should talk about that at some point. There's a guy on eBay trying to sell them for $250 each.....and to me that's NOT tolerable. Maybe $100 each?....I don't know. What were folks paying for them when they were available?

Material choice is pretty wide open......but they need to be made out of a material that makes sense. Also, parts can be made of different materials.........the printer doesn't care. You could make an aluminum hub with an integral steel liner...for example. Thermal expansion differences might make that not a good choice, but you see what I'm saying. It's a promising future for low cost parts production.

regards,
bob

Hi Bob,

yes very interesting subject. I have not seen a printer able to handle the heat of molten metal though. certainly not saying they don't exist as I am no expert at all. But in my mind, in order for something to be printed it has to be in a liquid state first. I could be completely wrong, just my thoughts.

If you have any links or info on how things could be printed using an iron based or other alloy material would be very interesting.

Technology is cool............. most of the time

Hi F18,

You're gonna love this technology. I've got to get out and shovel some snow, but just Google "Selective laser sintering". It's the same process as with the plastic powder 3-D printers, only the laser for metals is much stronger. Simply amazing technology. It's also called "additive manufacturing". Tons of videos on YouTube also. I've got a guy building me an internally supercharged diesel engine for a Navy project I'm working on and he's used this technology to build heads, cylinders, etc., in steel, aluminum, titanium, etc, etc. Fun stuff for sure.

regards,
bob

We were doing development work on aircraft engine parts and there is promise. The first problem is time, (hours on machine cost) a small engine part in the 2" x 1 /12" size was taking 8 hrs. to fab. A large brake drum might take 2 or 3 days and the there is the problem of material and ability to handle the stress loading a drum sees. Lots of things to consider and the safety testing and certification, etc. They are making lots of progress on the process though and who knows where it will lead. This was all rapid prototyping for preliminary testing only, no actual on engine tests. But we started with other state of the art unknown processes like EB Welding, Translational Friction Welding, Superplastic Forming/Diffusion Bonding, Inertia Welding, Laser Drilling and Welding, Water Jet, and they are all in our manufacturing box of everyday tools now, so, who knows where it will go.

CT

Don't forget the drums from an early (5-bolt hubs) M101 trailer are the same, and they don't get used much...you can trade 'em off and be a lot happier in a pinch.

Dennis

Dennis,

I think the cat's out of the bag on that one. There's a guy on Ebay selling M101 trailer hubs for (Gulp) $250 each! It seems inevitable that at some point new hubs are going to have to be produced.

regards,
bob

Why can't the old ones be spray welded back to thickness and then turned true? Who can do this?

Hi Just Me,

Maybe they can......I just don't know anything about that process. Anyone?

regards,
bob

The flame spray may work but there may be a problem with dissimilar materials and thermal cycling may cause the new material to crack off. Still worth looking into, especially with the scarcity of good drums. If you could only just internally sleeve them, ie; turn them to a specific dia., heat them up to high temp and drop a sleeve in and return them. I think the sleeve would be too thin though plus all the stresses.

CT