Dadio's 3D Printing Stuff

[Dadio]

This is my first attempt at 3D modelling and then 3D Printing a part , I've started with a fairly simple part , a front steering knuckle for a Yokomo Dogfighter YZ-834b , I thought i'd start with this as i need one and they are hard to find .
Comparison pictures of a real one and my printed part .
Real on the right .


Real on the left


There are a few bits that need revision , the hole for the track rod end is out of position, a couple of places could use a taper , the king pin hole is 0.5 mm to far from the edge and the taper towards the outer bearing is wrong , all that aside the only real reason it could not be used is the hole for the track rod end being too close to the edge making it weak .

[coxbros1]

Still cool!.....how long did it take to print?

[Dadio]

3 hours 20 min . just started printing a better version ....hopefully

[Dadio]

Two more not quite right versions , I can sort the errors out though as they were both over sites , there is some shrinkage occurring though so I'm going to have to oversize the bearing hole a bit , I'm thinking if this eventually comes out really well and I publish it for free on Thingiverse do I put dimensionally accurate sizes in or the dimensions that work and allow for shrinkage ? I'm guessing I should put the accurately copied measurements in so people can correct for the shrinkage of their printer and filament type ?

[GoMachV]

I make all my drawings at actual size, different machines will print differently and different materials will shrink differently as well. Best to let the end user decide imo. They can adjust the percentage to adapt to their machine

[ROH73]

In my opinion, publish the model at as designed nominal size. You can list the critical dimensions for reference if you like. In my experience, FFM printers always make holes undersized, which is actually fine. I always open the holes up to the correct size with a drill or reamer. They're often out of round anyway, so some minor cleanup makes for a much better part.

[Dadio]

And here they are my first usable shareable 3D printed parts ! For reference i deliberately extended the hole for the king pin retaining set screw by 1 mm , might go to an extra 2 mm in future .



Although you can't see it because it was on the bed the steering arm is fully radius'd around the edges in the file as per the real one .

[ROH73]

Looks great!!

[KidAgain]

Dang man great job.....................

[Dadio]

Thanks guys

[Dadio]

I think I followed most of that Dan ,thanks .
The part is now on Thingiverse as " Yokomo Dogfighter YZ-834b Knuckle " so you can have a better look at the file .

[Dadio]

I really do appreciate the help , I was trying to replicate the original part as a learning exercise and a shelf/semi usable part ,I only changed one bit the threaded hole for the king pin set screw I made 1 mm longer , I have A level design tech A level sculpture and National Diploma in Motor Vehicle Engineering as well as 25 years as a mechanic so I know a little of fatigue points a structural strength in designing stronger parts but that's not what I was trying to achieve here , I have a lath and mill that I can make structurally superior parts with .
The thing I really do need help with and where I appreciate your input greatly is the process specific to 3D printing methods like your tip on avoiding supports on overhangs .
I saw the whole build thread for that monster truck on RCGroups , very impressive !

[Dadio]

I'm so glad you didn't take offence at my last post , I really am grateful and I was worried you might take it the wrong way but I often feel with people you've never met you need to set a base line to the conversation like this .

[Dadio]

That's cool , it will be a while before I start thinking about gears although a gearbox case is not too far ahead of me .

[Dadio]

When making an exportable STL file it shows a wire frame of how the shape is built up of faceted triangles and you can tell from there that a serious amount of number crunching is going on , its no great surprise that when it starts to animate multiple gears meshing that it gets hot under the collar but so far I've only experienced one issue of unexpected behaviour , I tried to delete a component from a sketch and suddenly half the object disappeared ? I had to backtrack a bit to get around it , i assumed it was my error but I'm not so sure now