Hello,

So the last while been working on a few ideas. I am building a series planetary drives to try wind generator gearbox. Outside diameter is about 2 inch. Having some issues with accuracy and need to find out if it's the printer or software. Really sucks as nothing fits!



Due to having had the flu again awhile ago I am slowly catching up with some things around the house. Hoping to get back to airguns soon. We had a blast of cold and heavy, wet snow.

Happy airgunning.

Pedro

Planetary gears are really cool. There is a ship lock that uses a huge planetary gear to swing two boats at the same time from one lock to another, near stuff. Hope you get the accuracy issue figured out, let us know what you find.

I can understand why planetary gearbox/drive would be used for ship locks. The torque the gearboxes generate are incredible.

Very neat Pedro!

Love it.

Do you have some plastic there that is tough enough to make a functioning gearbox? Would be neat to try. Maybe a oil filled case O ring sealed. Might run a while.

I'm sure you can fiddle with it and get it going. Problem will be you can't just increase your ring gear for instance. The whole mess has to be a "set" to intermesh and work. Perhaps just print overlapping discs (no teeth) til you get your diameters right?

Gary

Hi Gary,

Many different plastics are available. ABS would be a good plastic to try for this. It is strong and machinable. I have seen gearboxes and dividing heads printed before. Be a neat project to try, a ring gear and worm to rotate it. I do need a dividing head eventually for my mill and might be a nice way to build one for not so accurate things.

A radii attachment for my mini lathe is another project i could potentially prototype but they are fairly simple to build.

Thanks for your suggestions.

Pedrog

Pretty impressive, hope you get it sorted out before too long.

I've been surprised several times when I've pulled things apart and found plastic gears inside where I expected metal, so plastic obviously works in some circumstances. I don't know how solvent resistant your filament is, but most times I've found a plastic gear train it was slathered in what appeared to be silicone grease.

It is pretty amazing that you can just "dial up" such a complex assembly. The resources that it would take to make an identical part out of iron/steel would be formidable

I haven't tried solvent in the PLA filament but it is corn based. I bought some acetone and it will eat up ABS plastic. One creates a slurry with acetone and ABS to make the ABS filament stick the to bed.

It is amazing how many things have plastic gears these days. I am sure many things are designed to fail. Keeps the companies buying more product after a year or two of service. Of course things break a week after the warrantly runs out.

I tried a few other settings but no idea why sizes are off. It could be that the accuracy is just that what it is. Regardless I tweaked the planetary gear design and made the diameter .010" smaller and the inside hole larger. After the holes where still tight so went to the small lathe drilled out to the closest size. Worked well after. Now I need to print 6 units to join in various configurations to try my idea.

With new gears.





Thanks for reading.

Pedro

Hi Pedro,
That looks neat.
To explain your reduction of size required, I guess you originally planned for enough clearance for your assembly and gears to rotate? I always design/make parts for too perfect a lock up. As if I were making a Rolex. Wondered if you did too.
Gary

My second attempt at a reply. Somehow first one didn't post. Bought a new toy, a Samsung Galaxy tablet. Got it used and is awesome.

Originally I had sized the planetary gears .010" smaller. This wasn't enough though. The carrier posts were drawn for .375" but came in at .390. A 25/64 drill thru the gears took care of the difference. Since PLA is a thermal plastic I used my heat gun to heat the posts and spin on the gears. This worked very well.

Printed more parts tonight, will have three units soon.

In my tool &die days accuracy was critical. Most of our automotive dies were .001" for block details and cutting sections were tightly controlled. We design with little or no clearance and tweaked ax required. I still design with accuracy in mind. But when designing for a company one has to ensure the appropriate tolerance is used for the correct application.



Edited 1 time(s). Last edit at 03/28/2015 04:45AM by pedrog.

Man! You are really making me want one of those printers. Seems every site I go to has an ad for one on the webpage margin somewhere.

Pssst. Say they're for an air gun handle so the management doesn't throw us outa here.

Lon



Edited 1 time(s). Last edit at 03/28/2015 06:30PM by Bigbore.

I suspected Pedro was either making a gyroscopicly stabalized Scope ... Or a Wankel Engine - since he mentioned "banks" and I see the design is possibly stackable .... Hummmmm

I find it nearly impossible to believe that you don't have one of these Lon!

Gary

multiple stages of planetary gear sets running in series can give incredible gear reduction ratios