Cutter Centering

Has anyone any tips or ideas for centering a gear cutter please. I'm trying to cut a 7 leaf pinion and the variation of only a few thou' seems to make a huge difference. I'm thinking of making a centering microscope but if there's an easier way I wold love to know

Many Thanks, David

You could try a cheap webcam, David

... the manually adjustable lenses can focus remarkably close.

MichaelG.

I made a centring micrometer similar to the one on this page.

**LINK**

Also useful for setting lathe tool centre heights.

Thank you Michael, I hadn't thought of a web cam. I'll have a think about how I could mount it.

David

Hello Steve, Yes, one of those was my other thought as an alternative to a microscope.

David

As far as a 'target goes' chuck a piece of small diameter bar and centre the end to a diameter equal to or just over the cutter tip width. File in situ to half the diameter of the bar and you will have a feature bang on centre with two lips the width of the cutter apart. You should be able to centre your cutter by eye or loupe to better than a thou by bringing the cutter up to the guage with one tooth at centre hight. Easier than trying to judge the middle of the cutter tooth if you are looking for bang on.

regards Martin

David

On the few occasions I have cut gears the method I used was to set the driving face of the arbor to 1/2 cutter width above the centre of the gear blank.

So with the gear blank mounted on the dividing head touch off (with a fag paper) the cutter arbor drive face to the OD of the blank at the top centreline.
Move the arbor clear of the blank and lower the spindle, or raise the knee half gear blank diameter minus half gear cutter thickness, lock all vertical slides. If using a commercial gear cutter the centreline should now be at the blank centre height.

Emgee

typo corrected

Edited By Emgee on 11/03/2021 12:16:01

Thank you Martin,

I haven't seen that before.

David

Hello Emgee,

Thank you. That was a bit of a headslap moment for me! I ought to have seen that.

David

Rightly, or wrongly, I have made the assumption that the centre of the cutter teeth will be on the centreline of the cutter.

So, measure the thickness of the cutter.

Touch the side of the cutter on the job (cigarette paper / feeler gauge ) Adjust cutter by half thickness and the cigarette paper / feeler gauge.

Maybe, I've been lucky, but this has worked sufficiently well for me.

But then I am not a clockmaker, so it may not suit.

Howard

Edited By Howard Lewis on 11/03/2021 14:47:17

Thanks Howard, your assumptions were correct, or if not correct, then they were allowed for. 

Thank you.

David

Edited By David Noble on 11/03/2021 15:49:26

Here's a quick & dirty demonstration of a cheap 640x480 UVC WebCam, David

Lens unscrewed sufficiently to give approximately 30mm working distance

Note: I had already removed the 'beauty ring' from the front.

The subject is the ubiquitous 0.5mm Pentel clutch pencil, which should give you a good sense of scale.

.

.

Better cameras are available ... but these are probably adequate for the purpose.

MichaelG.

That's very good Michael. Just to clarify, are you suggesting to use the camera as a centre finder or as an alternative to a loupe?

David

.

Well ... as it stands [which was cobbled together with a few lumps of BluTack] I suppose it's just an alternative to a loupe.

But if virtual cross-hairs were added, and the camera firmly mounted, it could easily serve as a centre finder.

I was just offering proof-of-concept, lest the naysayers jump in.

MichaelG.

Come on Michael, how do you add the cross hairs? I've had this on the back burner as a way of making a travelling microscope. Cross hairs and concentric circles would be good

.

As a Mac user with an interest in microscopy, I have several applications that allow the use of overlays.

... I presume that similar things are available for other Operating Systems.

You might want to look at ToupView/ToupLite : **LINK**

http://www.touptek.com/download/showdownload.php?lang=en&id=28

Despite being intended for the ToupCams, it appears to work nicely with a UVC camera as input.

MichaelG.