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Thread: Cross-slide dial inaccurate ?
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21st May 2020, 11:59 PM #1Senior Member
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Cross-slide dial inaccurate ?
I use a Hafco cl40a lathe. The cross slide dial is inaccurate and has been so since new as told by the previous owner. The lathe has an accurate DS10 DRO. I can verify by the DRO and my micrometer the lathe is accurate and can consistently be within 0.02mm on the final cut. Sometime better. However, the cross-slide dial is not even close. 1 mm on the cross-slide dial show 1.5mm on the DRO. 2.0mm show 3.0mm on the DRO and 5mm on the cross-slide shows roughly 8mm on the DRO. The DRO is correct. To me it looks like something is mismatched from new.
I’m thinking either the internal screw of the cross-slide dials are mismatched.
What do others think?
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22nd May 2020, 12:19 AM #2Golden Member
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Yes sounds like the dial is made for a different pitch feedscrew.
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22nd May 2020, 12:22 AM #3Senior Member
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Checking the parts manual, the cross-feed screw comes in either metric or imperial. I wonder?
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22nd May 2020, 01:04 AM #4Most Valued Member
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If it was an imperial 20 tpi thread 1 full turn would move 1.27 mm
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22nd May 2020, 05:24 AM #5
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22nd May 2020, 12:50 PM #6Most Valued Member
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My macson has 200 thou for 1 turn of the cross slide handle so that would have a 20 tpi thread. The hercus is 100 thou per turn so that would a 10 tpi thread. If you can measure 1 full turn then it should be easy enougj to work out the dial that you need.
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22nd May 2020, 04:47 PM #7Gear expert in training
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Easy way to check it...just put your DRO in imperial and see what it says for 1 turn
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22nd May 2020, 05:30 PM #8Most Valued Member
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There was a thread a few months back on 3D printing larger dials. Might be an option if you want to replace yours.
Steve
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22nd May 2020, 11:48 PM #9Senior Member
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Took some measurements.
1 full turn or 5mm on the dial measures consistently 7.99mm on the DRO. Close enough to 8.00mm. A factor of about 1.6
0.19" on the dial measures 0.2984" on the DRO. Which is a factor of 1.57 or close to 1.6.
The cross feed rod is metric and has a 4mm pitch.
All looks good so far. Found lots of swarf in and around the feed rod. Not suppose to get in there. I'm thinking something is worn. Broke my classes tonight so I will continue in a few days.
I will post some pictures later.
Thanks for the comments.
Regards,
Tom
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23rd May 2020, 11:46 AM #10Most Valued Member
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Your dro is set to read diameter, i have tried that in the past and did'nt like it.
I think it didn't seem to be as accurate as having the dro set to radius.
Set to radius also makes it easier when cutting to a depth for something like an o ring groove.
I have a cl410, it has a 4 mm thread and it is a newer model of your cl40, see pic of the crossfeed dial below.
One full turn is 8 mm on the dial and this moves the cross slide 4 mm. So this also is made to work with the radius of the job.
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23rd May 2020, 01:17 PM #11Senior Member
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Here is my CL40-A cross feed dial. Looks like a full turn is 5.1mm not 5.0 as I wrote.
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23rd May 2020, 05:15 PM #12Golden Member
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The dial is made for a 5tpi imperial leadscrew with a secondary metric scale for that pitch which is 5.08mm pitch. If your crossfeed screw is actually 4mm pitch then it will be out by some crazy amount such as the factor you have found. About the same usefulness as having no graduations on the dial at all. I'd be ignoring the dial and using the DRO. You could go to the trouble of making a new dial graduated to the actual pitch of the feed screw, but why worry, since installing a DRO on my mill I don't think I have even glanced at the dials.
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23rd May 2020, 08:05 PM #13Senior Member
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Well I disassemble components of the lathe. I have verified the cross feed screw is metric and 4mm pitch. All looks good and no signs of wear. I am sure the dial is a mistake. I will see if the later model will fit.
Sincerely,
Tom
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25th May 2020, 01:46 PM #14Senior Member
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I maybe able to buy a replacement dial from H&F.
I guess if 1 full rotation is exactly 8mm then half a rotation 4mm and so on. Could even go to 64 divisions of 0.125mm
The Dial diameter is 96.00mm which to suit.
Wondering if anyone here is willing to make a metric only dial for my lathe? If so PM me.
Regards,
Tom
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25th May 2020, 04:24 PM #15
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