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20th Jun 2021, 07:02 PM #1Golden Member
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Heavy boring lifting right hand side of carriage
I have an old Hercus 9” C which works beautifully. However I’ve always struggled with boring. I just can’t get a good solid setup to be able to consistently bore without chatter or a tapered bore.
Today I set about removing material from the centre of some hardened sprockets and I managed to find the source of my issue… the rear of the carriage is lifting.
I decided to drag the lock on the carriage as a way to stop if lifting and it worked wonders.
However I’m looking for a way to adjust the carriage.
Does anyone know if you can adjust the carriage on an old Hercus 9”? It seems like it floats on the bed and the only thing stopping it lifting is the gear meshing with the leadscrew.
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20th Jun 2021, 07:10 PM #2
Hi Neevo,
On the "Hercus" area there is mention of shimming the retaining plate at the back to reduce or prevent the carriage lifting.Best Regards:
Baron J.
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20th Jun 2021, 07:11 PM #3Golden Member
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20th Jun 2021, 07:24 PM #4Gear expert in training
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What style of tool are you using? Perhaps a more free cutting geometry would reduce the load a bit?
Gear cutting specialists and general engineers www.hardmanbros.com.au
Fine pitch gear cutting from 0.1 Module www.rigear.com.au
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20th Jun 2021, 07:30 PM #5Most Valued Member
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The only things keeping the saddle from lifting at the front are the rack and gear and in a slight way the half nuts.
Normally when conventionally turning ,boring or parting the load applied to the tool should be sufficient to hold the saddle to the bed.
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20th Jun 2021, 07:50 PM #6Golden Member
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The load with facing or turning seems to push the carriage down on the bed. So I have no issues there. Just boring.
I’ll have a look at some smaller boring bars with a more positive angle to reduce the load.
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20th Jun 2021, 08:10 PM #7Most Valued Member
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Your setup doesn't have the tip of the boring bar past the left hand side of the carriage does it?
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20th Jun 2021, 08:44 PM #8Golden Member
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Heavy boring lifting right hand side of carriage
Yes it does. What’s the alternative as the carriage is pretty close to the tool post.
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20th Jun 2021, 09:39 PM #9Most Valued Member
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Off topic, but that lathe looks like it could use a bloody good oiling.
Might just be the picture though.Chris
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20th Jun 2021, 09:40 PM #10
Hi Neevo,
I found this, I don't know if it is correct for your lathe, its from the South Bend lathe manual !
Saddle Gib Screws.pngBest Regards:
Baron J.
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20th Jun 2021, 09:41 PM #11Golden Member
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20th Jun 2021, 10:33 PM #12Most Valued Member
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No it doesn't I may have confused you or maybe I'm confused. Is that picture how it was setup? I was asking if the tool was to the left of the left hand end of the carriage.
If its being used as per the picture* I not seeing how it can be lifting the right hand side unless the carriage is worn so its not longer flat. "Adjusting" that means some scraping, but lets see what other think.
*and that I don't have the wrong end of the stick.
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20th Jun 2021, 10:37 PM #13Golden Member
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Yes that’s the setup. Admittedly it was less of an issue when boring in, but as I pulled the tool out again it would cause the problem. I assume because the tool is flexing as I bore which means it’s still cutting on the way out again.
It wasn’t a constant force lifting the carriage, but it would definitely happen as I pulled the tool out again.
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20th Jun 2021, 10:54 PM #14Diamond Member
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Ok i think i understand what is happening here. At the end of cut you aren't backing the tool away from the bore when you withdraw it from the hole? and it is taking a small cut when you withdraw it?
If this is the case i don't think your carriage is lifting, it is pretty common for boring bars* to spring away from the cut due to the cutting forces, then when you withdraw the tool the cutting force is less and the tool springs back and takes a very shallow cut.
* the spring can also be in the toolpost or cross slide/carrige wear.
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20th Jun 2021, 10:57 PM #15Most Valued Member
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Excerpt from the Hercus 260 Maintenance Manual. Yours will be the same I think.
Chris
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