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Author Topic: Made a new center setting gauge for the lathe today  (Read 11761 times)

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Made a new center setting gauge for the lathe today
« on: July 21, 2013, 04:17:40 PM »
I’m sure I’m not the 1st guy to make one but I haven’t seen another one like it yet.  I found a small .150” travel D.I. dirt cheap on ebay.  It’s small enough that it won’t hit the ways and explode if the spindle is accidentally turned on with it still in the chuck.




It’s calibrated with a .250” dowel pin that slides in & out of a close fitting reamed hole in the center of the shaft.  The indicator dial is set & locked so that the needle sits on zero with the dial tip extended exactly .125” It works great and is very consistent.  The only variable is making sure it’s set at 90 degrees to the carriage but that’s pretty easy using an accurate square.  I thought about adding a level but I think the square is more accurate.



A bonus is that it’s very quick and will work in all 3 lathes without any fiddling with D.I. stands & knobs like I had to do previously.
Milton from Tennessee ya'll.

Offline Hood

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Re: Made a new center setting gauge for the lathe today
« Reply #1 on: July 21, 2013, 05:03:12 PM »
Nice solution :) And as you say the square is likely to be more accurate than a level.


I toyed with the idea of using a webcam in the spindle and initial tests showed it would work very well but in the end I just used a height gauge on the saddle to set tool heights.
 When I made my own turret however I went to great pains to make sure I accurately machined the slots to suit 20mm tools and I have found that the very slight variance between different holders and different tips wasnt enough to be an issue.

Hood
Re: Made a new center setting gauge for the lathe today
« Reply #2 on: July 22, 2013, 01:23:05 PM »
Thanks Hood.  I love it when an idea actually works! :o

Funny, I was just snoozing & daydreaming a bit during my lunch break at work & it suddenly dawned on me: silly boy, back the tool up a bit, rotate the gauge 90 degrees & re-square it, jog the tool back until the tip is at zero again & voilá, instant tool table offset measurement!

It'll probably need a bit of a tweak to hone in on the "dynamic" tip position due to flex in the machine under cutting pressures but at least I'll have a consistent starting point. ;D
Milton from Tennessee ya'll.

Offline Hood

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Re: Made a new center setting gauge for the lathe today
« Reply #3 on: July 24, 2013, 03:39:32 AM »
Yes, should work well and wear offsets can be used easily to tweak things if needed :)
I always tweak the finish tools wear offset a bit so I leave about 0.5mm extra, once the part has had its finish pass I measure and the adjust the offset and rerun the finish pass to get it perfect.

Hood
Re: Made a new center setting gauge for the lathe today
« Reply #4 on: August 05, 2013, 09:29:57 AM »
...and rerun the finish pass to get it perfect.
How do you set up to run just the finish pass Hood?  I tried "Run from here" and had some trouble.  May just be my inexperience since it was the 1st time I've tried to use it.
Milton from Tennessee ya'll.

Offline Hood

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Re: Made a new center setting gauge for the lathe today
« Reply #5 on: August 05, 2013, 01:31:06 PM »
Yes, I just use RFH.
I often have a M5 then M1 in my code after a finish pass (also a thread) so that I can measure and adjust if needed, then once its correct (assuming I am doing more) I switch off optional stop.
Hood
Re: Made a new center setting gauge for the lathe today
« Reply #6 on: July 22, 2014, 04:50:43 PM »
I wonder if an edge finder would work. :o
Heading to the shop to try it out.
Re: Made a new center setting gauge for the lathe today
« Reply #7 on: July 22, 2014, 08:32:55 PM »
Make sure & post a pic to let us know how it works for you.
Milton from Tennessee ya'll.

Offline RICH

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Re: Made a new center setting gauge for the lathe today
« Reply #8 on: July 23, 2014, 08:04:31 AM »

Quote
I wonder if an edge finder would work.

I use an edge finder and it works great and is very accurate. I use the displayed DRO values to record the offsets.
Like Hood a height gage is used for setting tool height, and after the tool table is populated, I also refine the threading tool
offset.

The "trick" is to use Mach for measuring the offsets using a reference line (ie; the od and face of the edge finder), use mpg's to touch off to the edge finder, and use a different screen set to avoid the back and forth between screens. Also
the master tool concept is used.

Some where i have a write up of exactly how it's done.

RICH