Free Hobbing a Wormgear with Tap - A Design & Manufacturing Guide

[@lklmmedia4715]

Wow - I just gave this a go, after looking at ridiculous pricing for Worm gear sets, and sure enough just with an Aluminium blank on my Mini Lathe, Pretty much a perfect Worm. I was significantly impressed, and even mystified by the fact it did indeed Self index through the full 360 degrees, and seemingly not crossover in any section anywhere. Tested by replacing the 12mm Tap with a 12mm bolt, then engaging the cut against the bolt, giving a nice turning "gear" which I could put some pressure on and the lathe was easily turning it albeit with plenty of pressure from me. The good thing is too, I can easily work with AL blanks to get the process right, and with the length of the standard Tap, the blank I did was around 100mm across, so it allows for making a decent ratio of gear that I can then Slice to size for screwing to the back end of large assemblies that they need to go on - the AL blanks can then be used for testing and templating before moving to Brass. Can't thank you enough for this video! New Skill unlocked!

[@EvolventDesign]

Thank you for the nice words and we are really glad you had a great outcome. We thought this very old technique should see the light of day and it was fun to film. Your Mini Lathe is a very capable tool for this type of work, just needed the idea and a little knowledge. If your mini lathe has a leadscrew and can thread, you can make your own homegrown "tap" and it really opens the door to wormdrives. For the details on how to get the exact toothcount and gear ratio the answers are in our links below. There is a lot here: www.patreon.com/posts/fine-pitch-using-88354219?Link& and the numerical model will soon be in our software gearcalculators.com/ seen here kzbin.info/www/bejne/a4WQc2uDbpWgiaM

[@lklmmedia4715]

@EvolventDesign yes it has a lead screw, have considered doing threads, just another thing I haven't tried. But I guess if I made a tap, it means I don't need to worry about trying to find a steel bolt to make the worm gear out of with worrying it won't be thick enough to hold a grub screw to hold to the 6mm motor shaft I.e. just at hardware store now and thinking I need to go up to 16mm to have anything decent. But if I used leadscrew to create the tap, I would then do exactly the same speed to turn the Worm gear itself and it should match 100% Now...not sure I have a lathe bit appropriate for screws...so will order some, looks like they will get used!

[@lklmmedia4715]

@EvolventDesign also gear ratios aren't too much of a concern, my devices will be PWM controlled for rotation speed, so either way rough is ok as I need to program the PWM to have the accuracy And PEC calibration. But what I do definitely need is good depth in the gear...which itself lends me to thinking the larger the bolt and Tap combination I was to go, the more course the thread, and subsequently the groove depth should be deeper, I.e. more like a full cut worm gear...otherwise the danger in this application is needing to push the gears so tight together so they don't disengage that it actually causes undue torque resistance.

[@EvolventDesign]

@@lklmmedia4715Thread tooth forms are 1/2 as tall as true equivalent standard gear teeth. This is why using threads the engagement is good but not great. With your mini lathe you can make the depth of your threads deeper and your engagement will improve substantially. You sound adventurous, so try larger diameters for your “tap” and cut them deeper.

[@lklmmedia4715]

@EvolventDesign yeah that is the plan, basically cut as deep as the tap will go, which makes it look a little ugly...but the face can then be cleaned up on either the lathe or the CNC mill. I think the lathe will give a more even result, I don't quite trust the Mill's travel parameters at the moment...it might turn it into an oblate spheroid worm gear!

[@RRINTHESHOP]

Nicely done Andrew.

[@EvolventDesign]

Thanks, had fun on this project

[@sharkbaitsurfer]

This is just such a wonderful technique, I was down the rabbit hole looking at worm gears for making fine adjustments and getting lost in it all Thank you for sharing it Subscribed!

[@EvolventDesign]

Glad it was helpful! And thanks for the SUB!

[@robertmason8341]

Great video and like your style of narration. No bs, to the point and intelligent. Pleasant voice one can listen to also!

[@EvolventDesign]

Glad you enjoyed it!

[@sierraspecialtyauto7049]

What Randy said. Actually looks like a lot of fun to do.

[@ActiveAtom]

We love gear making. Lance & Patrick. We enjoyed this video it is great gear learning.

[@EvolventDesign]

Awesome! Thank you!

[@gerritvisser]

When done with an O2 steel blank this process also makes wonderful rope knurls :-)

[@chrisosowski8531]

Thanks for the cool video. Do you think this would work ok with an acme tap?

[@EvolventDesign]

The process in general should still work. The driver is the lead angle of the tap, if it will self-index the gear blank around in circles you are set. For the regular hardware threads they have rather pointy tap teeth and they index well. For ACME with the flat root and hence flat top on the tap - give it a try. Have not tried it with ACME threads. Thanks for watching.