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| The Sequel - Oh Blimey I bought a CNC Lathe (Beaver TC 20) |
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| awemawson:
Matthew, visually it looks OK but it's not the easiest of things to get a good view of. Once the start of the worm has meshed it feels pretty smooth, it's just the initial graunch as the start enters the spur gear. I presume I'm right in thinking that even though the spur gear is canted over at an angle (lead angle of the worm?) a straight cut involute without crowning cannot be an exact fit, just an approximation, needing scallops out of the centre of the tooth width that use is generating :scratch: Gear experts please comment ! |
| Spurry:
By no means an expert, but on a recent job, the gear definitely had hollowed teeth. Pic attached when trying to work out how to locate their respective centres. Pete |
| awemawson:
Now those (nylon?) teeth are cut at an angle to avoid canting the shaft but that's exactly the scalloping that my gear will end up with after not very long ! |
| WeldingRod:
Worm gear sets come in regular (what you have), single, and double enveloping. Non enveloping has straight wheel teeth but with a spiral angle. Single is when the wheel is grooved and the teeth are shaped into a curve: you can hob to get there. Double enveloping has an hourglass shaped worm and a shaped wheel. Load capacity goes up with number of envelopes. You probably need to deburr the worm ends. Also, the end of the worm should not be touching the wheel's teeth. It may be installed in the wrong axial location. If you want to wear.it.in, I would start with lower load or no load and wash the chips out regularly. Might feed it some pumice mixed into grease. Sent from my SM-G892A using Tapatalk |
| Pete.:
--- Quote from: awemawson on March 07, 2021, 07:56:54 AM ---Matthew, visually it looks OK but it's not the easiest of things to get a good view of. Once the start of the worm has meshed it feels pretty smooth, it's just the initial graunch as the start enters the spur gear. I presume I'm right in thinking that even though the spur gear is canted over at an angle (lead angle of the worm?) a straight cut involute without crowning cannot be an exact fit, just an approximation, needing scallops out of the centre of the tooth width that use is generating :scratch: Gear experts please comment ! --- End quote --- It can be either way but the scalloped arrangemet gives more tooth engagement. The bigger problem as I see it is that the worm starts are engaging with the gear. That says to me that the worm is too short because the start of the worm should never be in engagement. Perhaps the worm can be moved along with spacers to move the end of the worm away from the gear centrline on the loaded side? |
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