3D print worm gear to match COTS worm

[gintree78]

Hi, I'm hoping someone can point me in the right direction. I have a lab/prototype system I'm developing that uses a worm gear to index a test sample. These are very light loads and low speeds, but is highly space constrained. I want to use a COTS worm gear to drive a 3D printed worm wheel of my own design. The worm wheel needs some fixturing features along with a larger pitch diameter than seems to be available from stock gear suppliers.

I can't figure out how to determine the correct tooth profile for my worm gear. I have some information about the worm from the supplier (for example, an A 1C 5-N24 worm from SDP) like the pressure angle, lead angle, lead. The SDP models seem pretty good, but I don't know if the tooth profile is accurate and if it was, is that enough info to create the mating worm gear tooth profile?

Anyway, if anyone could help point me in the right direction or give me some tips/references that'd be great!

Thanks.

-John

 

[3DDave]

Give it a shot - after all, this seems to work:

https://www.youtube.com/watch?v=j7RtOP9Kh_Q

 

[gintree78]

Ha! Customer might raise an eyebrow at that! Still on the hunt for a good way to do this though...

 

[3DDave]

This is how they are usually made for higher loads:

https://youtu.be/-umcQtrn1CQ?t=1005

You can see that the worm wheel isn't generated by itself but by iterative cuts from the worm gear shaped hob.

An approximation would be a spur gear with helical teeth to match the advance angle of the worm gear.

 

[gintree78]

Thanks for the response 3DDave. Cool video for sure, but overkill for my application. I ended up installing the 10-day evaluation of camnetics which is awesome! If I end up doing more of this work, I'll definitely buy the package. I entered all the worm parameters to meet the COTS worm I am using and it generated a model of the wheel and worm. The creator of the software says these models are sufficiently accurate for 3D printing, so I think I'm good.

If I didn't use camnetics, the spur gear w/ helical teeth would have been a good alternative. Maybe I'll try both and report back.

 

[3DDave]

Excellent. I thought of suggesting some dedicated software, but there are a lot of them, most quite expensive. I'll add camnetics to the list.

GearTrax for Solidworks

KISSsoft

Sizing calculations are available for all common gear types (cylindrical gears, bevel gears, worm gears, helical gears, hypoid gears, and crown gears). For cylindrical gears, the software also works with planetary sets and gear racks. In addition to a feature for reviewing calculations with respect to standards (ISO, DIN, AGMA, VDI, Klingelnberg), the program also offers a number of different design and optimization functions.
Also includes full transmission design/analysis

Gearotic

http://www.gearotic.com

(external link)

Spur, Helical. Bevel, and Crown; Involute, Cycloidal, Random, Geometry, CNC

Romax Designer

Gear noise prediction/simulation see Eliminating Gear Whine

ZAKGEAR *
Spline, Spur, Helical, Spiral Bevel, Gleason; Involute, Spirol?; Geometry, Inspection, Stress, CNC

 

[drawoh]

gintree78,

Worm gear profiles should be described in your machine design textbook. I have modeled a worm and gear, although I did not do rapid prototyping. On the other hand, rapid prototyping is not a precise process, so you do not need to get the profile exactly right. The plastic will smooth itself to shape when you run it.

Is there any reason you cannot go to a gear fabricator with an engineering drawing? The part can be made from metal. You specify the tooth clearance you want, and you give them the worm so they can test it.

--
JHG