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mekanik
26-07-2017, 10:54 AM
Hi Guys
Just got an email from the instructables website and thought i would share, gears made easy using Fusion 360.
http://www.instructables.com/id/The-Easy-Way-to-Design-Gears-in-Fusion-360/?utm_source=newsletter&utm_medium=email
Regards
Mike

magicniner
26-07-2017, 11:16 AM
Just share a link to the McMaster Carr website which supplies the solid models of the gears they sell which this guy simply downloads then modifies, those with something to hold their ears apart can figure the rest in the CAD package of their choice.

It might just be me but I've generally started to ignore "Instructables" links in emails or search results because simply posting on there seems to require a total inability to get to the point, thanks for the reminder that this is still the case ;-)

- Nick

MartinS
26-07-2017, 11:59 AM
Initially I wonder whether the download file is the "design" or just a "representation" of the gear in question. i.e. is the tooth surface simply part of an arc that is "close" to the involute surface? Also with low tooth numbers, there is a natural undercutting in the tooth root. Is this correctly reflected? If not, there will be a tip/root interference and a "clunky-ness".

Mind you, from the roughness of the surface of 3d printed parts that I've seen, the above is irrelevant!

Two pinches of salt from me.

I'de just buy the McMaster version (or similar)

-Martin

EddyCurrent
26-07-2017, 12:06 PM
To be fair though, that method does seem somewhat normal for a large proportion of the 3D printing gang and at the end of the day they think they've done a great job.

mekanik
26-07-2017, 01:47 PM
To be fair though, that method does seem somewhat normal for a large proportion of the 3D printing gang and at the end of the day they think they've done a great job.
Thanks for that Eddy(and welcome back to the forum)
That was my intended target, there are a lot of professionals on the forum that are fully upto speed on all that Fusion is capable of, but as i am a novice i thought it might have been of some use for people like myself.

MartinS
26-07-2017, 03:23 PM
Hi Mekanik

A useful idea. Another is here:

https://www.youtube.com/watch?v=KbhSQZ236EE&feature=youtu.be

In this one the presenter details the McMaster method but continues to outline a plugin for Fusion 360 that allows the creation of the tooth surfaces within the CAD process.

If anyone decides to check it out, the McMaster parts list DOES have the diametral pitch on the list. It is called "pitch". But, the McMaster listings only has imperial "DP" gears not metric "module" gears (although DP and metric can be mixed if you can get your head around the maths & formulae). Note also that 14.1/2 pressure angle gears went out with the ark..........20 degrees is the norm now.

I posted a reply a couple of hours ago that vanished! (must have pressed the wrong button) in which I poured a little cold water on the idea of using this method as the design for a 3d printed gear. To me, the tooth surfaces look as though they could be parts of an arc rather than an involute curve, or even a series of arcs that follow an involute within an acceptable error boundary. Also the root shape and clearance looks a little iffy! Mind you, compared to the general surface finish of a 3d printed part, the above pales into insignificance!

The above is fine for providing a visualisation of a gear drive in a solid model. It's also fine if conventional gear cutting methods are used (assuming that the tip diameter and centre distance are correct in CAD). If 3d printing is to be used, I would advise the checking of some of the major proportions that McMaster or Fusion comes up with (tip dia, root dia, root fillet radius etc).

I'll help with formulae and guidance if needed.

-Martin

mekanik
26-07-2017, 03:58 PM
Hi Martin
Thanks for your post, sheds more light on the subject.
I am more of a lurker on the forum, i don't have a CNC machine or 3d Printer but thought my post might have been usefull to others, I wouldn't contemplate using a printed gear myself, and fortunately i can machine a reasonably accurate gear from solid.

cropwell
26-07-2017, 04:59 PM
To be fair though, that method does seem somewhat normal for a large proportion of the 3D printing gang and at the end of the day they think they've done a great job.

I used to download objects from thingiverse, many designs are flawed (for example - an articulated dinosaur the grandchildren wanted had two pairs of left legs !) I messaged the guy that posted the object file and his response was 'Duurrr'. :apathy:

Cheers,

Rob