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Thread: Parting off on Hercus
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18th Nov 2009, 12:46 PM #1Senior Member
- Join Date
- Jan 2009
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- Captains Flat
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Parting off on Hercus
Dear All
How have experienced Hercus users mastered the challenge of parting off? I am aware of (but have not experienced) the frightening dig in risk of parting off. I am aware that Myford reduces this risk by rear (upside down) parting off tool post. I am also aware that goosneck parting off tool reduces dig in risk via its inbuilt "spring". I could part off by running lathe in reverse and upside down the parting off tool except when work held in chuck as this would unscrew my chuck (thread mounted not camlock).
So, any useful tips appreciated.
David
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18th Nov 2009, 01:56 PM #2
Parting tools dig in either because there is enough flex in the system for the job to ride up or the tool height wasn't set right at the start. Jobs in the hercus tend to be smaller and thus more flexible, the machine is generally less stiff, and operators tend to be less experienced and thus don't set up properly.
I'm a big fan of a big stiff parting tool (note I specifically inserted the word parting to put you children off ) but if you bother to get your grind right, height and angle right, everything is nice and tight, and make sure your as close to your chuck as possible it'll go smoothly.
Parting is just a high load job so you have to be more precise with setup. Cutting a diameter you can be off and it'll still be fine, parting is just less forgiving.I'm just a startled bunny in the headlights of life. L.J. Young.
We live in a free country. We have freedom of choice. You can choose to agree with me, or you can choose to be wrong. Me.
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18th Nov 2009, 04:27 PM #3
Bad move tool digs in tool snaps and broken bit flies up at you . have never liked upside down parting off for that reason
The parting off tool should be set just a touch above centre height to allow for the flex in the tool and post ( it pulls it down to centre height as it cuts)
If you have power cross feed use it to part off , ( you get far more tool breaks if its hand fed)
Lock the saddle when parting off
To find centre height wind the parting off tool in and place a 6" rule vertically against the job , keep winding till the tool just holds the rule in place, if the rule is verticle your at centre height , if the rule is at a slight angle you are either a touch above or below centre height adjust and get the centre height right most important
Grind a slight taper across the cutting edge so one side of the parting off tool gets to the centre first , this leaves a small dimple on either the section parted off or the remaning stock , but it gives you a clean cut and the dont get the bit being parted off in a wiggle or damaged
If its a large diam remember you need to run at a higher speed as you get to the centre to keep the cutting speed up , ie part 1/2 way in , withdrar the tool , change speed and then finish parting off
Have fun , parting off is always an adrenalen rushAshore
The trouble with life is there's no background music.
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19th Nov 2009, 08:56 PM #4Senior Member
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- Jan 2009
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thanks
Thanks to all advice on parting off....I am going to give it a go - fingers crossed
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20th Nov 2009, 11:26 AM #5
If you've got some brass that's a good material to try first. Stiffer than aluminium but softer than steel and chips rather than making long swarf tails. Keep your tool as close to the post as you can and part as clos to the chuck as you can and generally keep everything as stiff as you can. Should be fine.
2c.I'm just a startled bunny in the headlights of life. L.J. Young.
We live in a free country. We have freedom of choice. You can choose to agree with me, or you can choose to be wrong. Me.
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21st Nov 2009, 06:18 AM #6Member
- Join Date
- Sep 2008
- Location
- Prince George BC Canada
- Posts
- 89
lube
A key point to parting operations which gets neglected is ....... USE CUTTING OIL!
The 3 main things you can do to increase your success rate are:
1, The most rigid setup you can do. (close to chuck, shorten tool as much as you can,maybe even use a tailstock centre)
2, slow your rpm down
3, use cutting oil liberally!Remember if the ID exceeds the OD the hole will be on the outside!
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21st Nov 2009, 09:38 AM #7
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21st Nov 2009, 09:48 AM #8Ashore
The trouble with life is there's no background music.
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