Author Topic: Jig grinder how does it works?  (Read 1594 times)

Offline PekkaNF

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Jig grinder how does it works?
« on: October 23, 2016, 12:50:10 PM »
Some time ago I gound Suburban tools videos and there is some iteresting stuff on jig grinders:
https://youtu.be/OPNS8iygqA0
https://youtu.be/du-1f1_FnBg

But how the Jig grinder spindle orbital mechanism works?

All that diameter adjustment and such. Jig grinders has ajustable planetary (orbital?) and reciprocating motion (oscillating) movements. I tried to google those mechanisms for hours, but could not find any illustrations.

Once I almost bought a little Hauser, unfotunately the all up price was too steep for me.
http://www.lathes.co.uk/hauser/page4.html

Pekka

Offline BillTodd

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Re: Jig grinder how does it works?
« Reply #1 on: October 24, 2016, 03:48:30 PM »
Ok .

This really needs an animation but I don't have time ATM.

Essentially the mechanism is a crank, but instead of the crank-pin being parallel to the main bearing axis it is angled and extended so that at one end it is concentric with the bearing axis and at the other it has maximum offset .


The orbiting mechanism  (OM) is connected to the crank by a spherical bearing which slides up and down the crank-pin. usually the whole crank shaft slide up and down as it is adjusted  and the OM stays in the same plane, thus as the relative positions of the crank and OM change so does the size of the orbit.

Often two cranks are used which allow phase variation as well as amplitude allowing ellipses at any angle as well as circles.

Hope that makes some sense

 
Bill

Offline BillTodd

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Re: Jig grinder how does it works?
« Reply #2 on: October 24, 2016, 06:22:19 PM »
actually, that may even be simpler

The knob at the top pushes down on a taper which forces a sliding grinding spindle away from the centre line of the large vertical spindle .

Bill

Offline PekkaNF

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Re: Jig grinder how does it works?
« Reply #3 on: October 26, 2016, 05:46:57 AM »
I did not get the crank description. The taper one sounds fine.

Apparently there is a orbiting pneumatic spindle and because this spindle orbits/rotates it needs a rotary coupling for pneumatic supply?

In it's simplest form like taper - boring head - spindle with rotary union:
http://d2n4wb9orp1vta.cloudfront.net/resources/images//cdn/cms/MMS_0710_millingwithair_1.jpg

Pekka