Worm and Worm Gears

[bolsover]

I'm in the process of reverse engineering the dividing head I use on the lathe and needed to draw up a couple of worms together with the mating worm gears.
I thought I'd share here in case anyone else needs worms!
Calculate the values using WormCalculations.xlsx and enter into the input variables in Worm.AD_PRT.
The Alibre part file only works for single start worms but is easily modified if you need a 2 or more start helix.





David

 

[Cator]

Thanks David for the resource.
It would be nice to have a tutorial on using this tool for those who want to take full advantage of it!
Maybe @HaroldL or @Ken226 could help us with their experience on video tutorials.
Regards
Francesco

 

[HaroldL]

I'm no expert in gears so maybe a written tutorial, by the originator, would be in order for this - in PDF format. Then it could be printed out as a desk reference.

 

[bolsover]

@Cator @HaroldL
Thanks both for the feedback. I'm actually thinking about building this into my utilities Add-On. The spreadsheet and part file are helpful when you only need the Worm but I guess most people will want both Worm and Worm Gear. My existing utilities Add-On can generate helical gears corresponding to a simple Worm Gear (as used on the dividing head). What I would really like to do is produce a utility that can handle Worm Gear 'Crowning' where the gear teeth are actually radiused to match the Worm.

https://upload.wikimedia.org/wikipedia/commons/c/c3/Worm_Gear.gif

How to do this in Alibre though? I suspect quite difficult since the teeth will need to follow curves on two directions.

in the meanwhile, I'll try to put together a simple guide for the Worm and upload as .pdf.

David

 

[albie0803]

Worm Gear 'Crowning' where the gear teeth are actually radiused to match the Worm

This often happens during the grinding of the worm tooth as the wheel is a disk against a twisted surface. The same sort of thing happens with the wheel as it rotates past the Vee shaped cutter

 

[bolsover]

This often happens during the grinding of the worm tooth as the wheel is a disk against a twisted surface. The same sort of thing happens with the wheel as it rotates past the Vee shaped cutter

I've been trying to decide how a crowned Worm Gear might be modelled. I tried a boolean subtract - looked promising with just one Worm being subtracted. But of course you can't do a circular pattern of a boolean - Grr.
I pressed on and tried adding new planes and a couple of booleans but very quickly ended up in boolean hell.

I'm now thinking a swept cut might be the answer - not tried but I suspect there will be problems if I try to sweep anything other than a circle.

David

 

[DavidJ]

You can use patterns inside the Boolean tool...

 

[bolsover]

@DavidJ Thanks - I should have tried that! Looks like a good approximation of what a gear cutter might achieve.

Just need Booleans and Circular Patterns adding to the API now

David

 

[pridbor]

Interesting topic!

But my PC froze up when I started to go through, opening edit for, the individual design steps, using the attached design in your last post.

I just updated to Alibre Design 26.0.0.26040.

Preben

 

[bolsover]

Interesting topic!

But my PC froze up when I started to go through, opening edit for, the individual design steps, using the attached design in your last post.

I just updated to Alibre Design 26.0.0.26040.

Preben

Mine didn't freeze - but did take a loooong time to apply the boolean.