Is it possible to measure Helical gears without Rotary Table

[[Pa...]]

I have helical gear (helix angle 19.5 Degree, gear length 7mm)

I am having difficulties to measure it without rotary table. Is it even possible to measure without RT?

I found out this video from Zeiss, where it is showing measurement of helical gear without RT.
Please see this video (From 00:32 to 1:10 min)
https://youtu.be/m9xd4olLHgY?t=32

However, when I reached out some Zeiss training centers, they said: "This is a matter of the tool maintaining contact with the surface. Travelling along the lead or profile will require motion in four directions in order to maintain your pitch. This is not possible on the CMM moving in only three directions. The rotary axis provides the fourth direction, allowing for the proper inspection"

Any comments?

[[Ch...]]

Yes of course,

This should totally be do-able in Gear Pro without RT - in Global technology just choose 3 axis scanning. I'm pretty sure I've done it before.

You just have to find the right angle probe or probe(s) that will not shank on the shaft.,

Depending on the size and pitch of your gear, this may require a 4-star stylus or even 8-star stylus.

[[Er...]]

Seeing as how a Zeiss video from 2013 shows an XXT with an 8 star system measuring a helical gear it should be possible in 2022. 🤣

Their catch phrase may be "proper inspection." Or they may have only seen it done with an RT?

[[Pa...]]

ok

[[Ch...]]

Can you click on the drop down for single points and change it to scanning ?

[[Pa...]]

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Yes, but there is only one option 'Single point probing'. My other programs shows me 2nd option 'Scanning'.

I guess there might be a toggle option somewhere to enable it.

[[Ch...]]

Is the probe you are using in Calypso have ability to scan ?

Yes strange, not sure why you would not have scanning. Must be a setting toggled off somewhere.

[[Ma...]]

I think that measurement of helical gears without a rotary table has some limitations. Full scanning measurement of helix (lead) can be very difficult on a part with a combination of high helix angle, long face width, and low number of teeth. Very high accuracy levels may also be difficult to achieve due to the error between stylii.

[[Pa...]]

Thank you for your inputs. I have succeed to measure it without RT. 🙂

[[Ch...]]

Parth,

Congrats, can you share a report, and/or picture of probe set up ?

Thanks,

[[Pa...]]

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I used Star probe, and assigned each probe to tooth on 0°, 90°, 180° and 270°correctly. The gear I am measuring has 7mm face width only.

Make sure shank does not touch the tooth.

For Profile/Lead measurement, I selected 3-axis scanning.

Limitations:
- Only measure 4 tooth (up to 8 tooth max if you use 8 stylus)
- For pitch/root dia/tip dia - you have to only rely on 4-8 teeth

img.jpg

[[Ro...]]

Gentlemen, an additional information, since long time GEAR PRO supports also the "automatic stylus selection" method.
With this functionality a manual link between tooth/gap number and stylus number is not necessary - the software will change the stylus automatically when necessary. That means, that also on parts with a big helix angle and long face width helix can be measured with two or more styli without doing a manual stylus change on the flank. Also with a typical pattern of 8 styli the pitch measurement can be measured on all teeth. Details you´ll find in the user manual of GEAR PRO. GEAR PRO 2021 (6.6) in chapter "Strategy 10-87" => "Automatic stylus selection 10-103" (in older versions of the user manual search for "automatic stylus change". I never do a program without this functionality because the only thing that I as operator have to look for is a clever design of the stylus system. That means the stylus tip diameter has to be small enough to get access into the root and in best case the styli have a long shaft that shaft contact is minimized. Just try "automatic stylus selection" - I bet you´ll love this functionality.