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3rd Nov 2020, 11:27 PM #1Senior Member
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- Victoria, Australia
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Half nut engagement with mal calibrated chasing dial!
I have a CL40A lathe. Again I find something not correct. My chasing indicator for locking the half nut to the lead screw is off by about 15 degrees. I managed to work around this by finding the engagement point for the 2.5mm thread and marking the point with a marker. This worked well, it just means I have to mark for each new type of thread.
I will try and figure out how to align the engagement markers with the correct thread.
Just wanted to vent. Any comments or suggestions?
Regards, Tom
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3rd Nov 2020, 11:39 PM #2Most Valued Member
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- Jul 2010
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- Melbourne
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I assume its a metric leadscrew?
Cant you just adjust the gear on the bottom? or is it keyed?
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3rd Nov 2020, 11:41 PM #3Senior Member
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- Victoria, Australia
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The gear is keyed. Best would be to rotate the Decal. Metric Lead screw.
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3rd Nov 2020, 11:48 PM #4Most Valued Member
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I think I'd use a pencil mark.
But if it troubles you, you could adjust the spacer length to get the timing correct. Though you'll likely need a different spacer for each gear.
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4th Nov 2020, 01:17 AM #5
Hi Tom, Guys,
Most likely the self adhesive disc with the markings has not been stuck down in quite the right place, rotation wise. Just peel it off and re-stick it !Best Regards:
Baron J.
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4th Nov 2020, 08:36 AM #6Most Valued Member
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I'm no longer sure that would work, though I think its a H&F issue. Your dial has 7 numbers, for some reason the one on H&F's L600D(which they say is your lathes replacement) has 8 though the indicator table hints that that should be 7.
https://images.machineryhouse.com.au...asing-Dial.jpg
If you are using a 14 tooth gear then adjusting the spacer will work. For the other tooth counts you'll only be able to get it "right" on one number, but as those pitches only use one pickup that's fine.
I've been known to set the timing so I am closing the halfnut on the trailing flank of the leadscrew, it drops in so nicely.
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4th Nov 2020, 09:19 AM #7Golden Member
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- Apr 2018
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- Drouin Vic
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- 633
I re-manufactured the half-nuts on my lathe years ago and the dial didn't end up aligned with the mark. I made a new mark and ignore the old one. It's no biggie but I guess it would be annoying on a new machine.
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4th Nov 2020, 09:55 AM #8Most Valued Member
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- Apr 2012
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- Healesville
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- 2,129
The cl410 is the same, the number comes around and you apply gentle pressure on the lever and it drops in past the line.
Its no biggie and mosts lathes are probably same.
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4th Nov 2020, 11:20 PM #9Member
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- Nov 2009
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- australia
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- 57
You have a bloody good lathe to do thread cutting with, so why bother to try and engage that silly thread chasing indicator, just leave the HALF NUT engaged and reverse the chuck.
The lathe you have, has got a good foot brake to stop the chuck, so when you are at the end of the thread cut, stomp on the brake hard and move your cutting tool away from the job.
Just chuck it into reverse and when the tool tip gets back past the start point, stomp on the brake and advance the tooltip and put it into forward gear and start cutting the thread again.
You can get so good at doing this simple procedure ,you will wonder why you ever bothered to even contemplate using that stupid thread chasing indicator.
My boss watched me doing it this way and he reckoned it was just about as quick as the CNC lathe he was using, oh, you can even cut threads at 600RPM if your game to give it a go.
600 RPM sure gives a very good finish on the thread as well, kind of a mirror finish to the threads.
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5th Nov 2020, 07:44 AM #10Most Valued Member
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5th Nov 2020, 11:47 AM #11Most Valued Member
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I think the chuck that i have on my cl410 weighs nearly 40 kgs so i wont be trying that, i have tried thread cutting at those speeds on a smaller lathe, a colchester,
and was not happy with the stress or the finish and find it quicker to wind the
saddle back and use threading dial. I pretty much only reverse out when cutting a metric thread on an imperial lathe or vice versa.
I am happy threading at 150 - 275 rpm and get good finish and fit at those speeds.
Back to the threading dial...
I'm pretty sure that when you change the gear on the dial it changes the position again so no point
in remarking anything.
I always have a bit of a test run before cutting to see where the half nuts are actualy
engaging in relation to the dial and commit that to memory.
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5th Nov 2020, 01:42 PM #12Member
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- Nov 2009
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- australia
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So your chuck weighs in around forty kilo, wow, seems to be a very regular weight for a chuck of about that size.
Maybe it's you who is just scared to try something that works very well, OK, that means you just stay in the dark ages and do it your way.
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5th Nov 2020, 02:08 PM #13Most Valued Member
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5th Nov 2020, 03:04 PM #14Most Valued Member
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- Aug 2011
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My threading indicator is off too. I just make a mark with a whiteboard marker and stick to that.
If I was fussy, I would shim it out from the carriage to get it spot on but I'm not fussed.
Simon
Sent from my SM-G970F using TapatalkGirl, I don't wanna know about your mild-mannered alter ego or anything like that." I mean, you tell me you're, uh, super-mega-ultra-lightning babe? That's all right with me. I'm good. I'm good.
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6th Nov 2020, 09:22 PM #15
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