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shedhappens
14th May 2019, 05:35 PM
G/day metal heads.

When you are putting a piece of stock in the 4 jaw chuck sometimes you might use a ruler and eyeball it across the jaws or maybe you just eyeball the rings on the face of the chuck in relation to the chuck jaws, sometimes you might get the bar stock close to centre but more often than not when you put your dial indicator on the bar stock it takes on the appearance of a clock on a time machine.

Using a ruler with a strategically placed 90 deg bend will place your bar stock (or pipe or whatever you are putting in the chuck) very close to centre in only a few seconds.

I seem to usually get within .010" to .030" from centre when nobody is watching and I am nearly blind as a bat.

I found the appropriate place to bend the ruler by dialing in a 40 mm dia piece of stock just tight enough that I could grab the stock and slide it out of the chuck by hand. You can use any diameter you like but just remember to set the ruler measurement to the radius of your stock.

Then placed the ruler on the jaw at the 9 o'clock position and aligned the 20 mm (for 40mm stock) line on the ruler with the chamfer at the outer edge of the chuck and then used a small square placed on the underside of the jaw with the blade of the square pointing up and against the face of the jaw and noted the measurement on the ruler to place the bend, soz, no pics of this but if anyone does not understand then I will do a pic.
You might have to tweak the bend a bit to get it right.

In use you set 2 jaws 90 deg apart to the radius of the bar stock, for example 50 mm dia bar stock you adjust the rule/jaw to 25 mm. For 60 mm dia set it to 30mm.
After you have adjusted the second jaw you rotate that jaw down and sit your stock against the 2 adjusted jaws and then nip up the remaining 2 jaws then indicate and do your final adjustments.

I have not done it yet but I think this method of setting the jaws will be real a winner when setting up an odd shaped something with an offset hole to be bored.

cheers, shed

Snapey
14th May 2019, 11:30 PM
So you've drilled a pilot hole & now for the 20mm dia drill to finish but when starting to drill you get a lot of chatter. You'd swear it's trying to drill a triangular hole.

Easy remedy & you'll polish the hole at the same time. Grab a piece of rag about 6" square & fold it 4 or 5 times, put it between the drill & pilot hole then drill. No chatter because the rag has filled the flutes thus supporting the drill.

adbuch
15th May 2019, 04:12 PM
Lots of good handy tips here. Thanks to all who have contributed.
David

Desert Hybrids Precision (http://www.desert-hybrids.com)

4me
15th May 2019, 07:12 PM
If roundness is important when drilling holes I've found the only way is to firmly secure the material to be drilled. Just hanging on to the material results in an odd
shaped hole.

BobL
15th May 2019, 08:33 PM
So you've drilled a pilot hole & now for the 20mm dia drill to finish but when starting to drill you get a lot of chatter. You'd swear it's trying to drill a triangular hole.

Easy remedy & you'll polish the hole at the same time. Grab a piece of rag about 6" square & fold it 4 or 5 times, put it between the drill & pilot hole then drill. No chatter because the rag has filled the flutes thus supporting the drill.

I realize you were referring to a lathe with controlled feed but I just thought Id try this on a Drill press. The pressure needed to break through the rag made the bit grab and dig into the work piece.

pipeclay
15th May 2019, 10:24 PM
I think his remedy is for use on a drill press, maybe you didn't need to fold the rag as many times or your rag material may be thicker than what was used in the example.

Ropetangler
15th May 2019, 10:38 PM
I have heard of but never tried this, same modus operandi, but instead of rag, folded up emery cloth. I have seen multiple references to this over the years, so it must work I would think, but I have not tried it myself nor do I know anyone who has.

Snapey
15th May 2019, 11:37 PM
I realize you were referring to a lathe with controlled feed but I just thought Id try this on a Drill press. The pressure needed to break through the rag made the bit grab and dig into the work piece.

I've never bothered with rag or a pilot hole on the lathe with something as small as a 20mm drill Bob. I'd use the 20 as a pilot drill for something over 32 maybe but my lathe is not a toy. If you need a lot of force to break through the rag then you have too much but it's also difficult with a hand drill because you need to control the pressure.

I probably should have stipulated in my original post that I use the rag on a drill press only and not a lathe although I've used rag with a hand drill up to 1/2" on occasions. Slow speed and coolant also help.

jack620
26th May 2019, 04:45 PM
I made the bent ruler that shehappens showed above for pre-setting the 4-jaw chuck. It works really well, especially when setting the jaws for rectangular stock. I did a test bend on the ruler and it cracked almost all the way across the bend. For the final bend I heated the ruler to red hot at the bend location and let it cool slowly in the hope of annealing it. It still cracked almost right through. I was able to reinforce the bend with silver solder. As shed said, the bend needs to be tweaked to get the measurement right.

To get around both issues perhaps a brass or aluminium attachment could be made to clamp onto the ruler at the appropriate place. It would just need a bandsaw cut to accept the ruler and a grub screw to lock it in place.

STEVEMORSE
7th Mar 2021, 01:27 PM
G/day metal heads.

When you are putting a piece of stock in the 4 jaw chuck sometimes you might use a ruler and eyeball it across the jaws or maybe you just eyeball the rings on the face of the chuck in relation to the chuck jaws, sometimes you might get the bar stock close to centre but more often than not when you put your dial indicator on the bar stock it takes on the appearance of a clock on a time machine.

Using a ruler with a strategically placed 90 deg bend will place your bar stock (or pipe or whatever you are putting in the chuck) very close to centre in only a few seconds.

I seem to usually get within .010" to .030" from centre when nobody is watching and I am nearly blind as a bat.

I found the appropriate place to bend the ruler by dialing in a 40 mm dia piece of stock just tight enough that I could grab the stock and slide it out of the chuck by hand. You can use any diameter you like but just remember to set the ruler measurement to the radius of your stock.

Then placed the ruler on the jaw at the 9 o'clock position and aligned the 20 mm (for 40mm stock) line on the ruler with the chamfer at the outer edge of the chuck and then used a small square placed on the underside of the jaw with the blade of the square pointing up and against the face of the jaw and noted the measurement on the ruler to place the bend, soz, no pics of this but if anyone does not understand then I will do a pic.
You might have to tweak the bend a bit to get it right.

In use you set 2 jaws 90 deg apart to the radius of the bar stock, for example 50 mm dia bar stock you adjust the rule/jaw to 25 mm. For 60 mm dia set it to 30mm.
After you have adjusted the second jaw you rotate that jaw down and sit your stock against the 2 adjusted jaws and then nip up the remaining 2 jaws then indicate and do your final adjustments.

I have not done it yet but I think this method of setting the jaws will be real a winner when setting up an odd shaped something with an offset hole to be bored.

cheers, shed..........THATS A BLOODY FANTASTIC IDEA. IM SO SICK OF SPENDING SO MUCH TIME ADJUSTING MY 4 jaw