Thread: What did you learn today?

If by rock solid you mean no movement of the work piece,then yes.

If you meant running true with no visible movement on your dial gauge then yes ,although in most instances as long as it is within tolerance it will be fine.

You wont always have the dial reading the same around a diameter,due to work not always being round.

Sometimes a piece might be round for almost its entire circumference,but dip in a low or high spot,in this case the same reading over 3 jaws would be fine.

The same would apply to some type of ovality,the same reading over opposite jaws would be fine.

The hard part is deciding when to stop chasing the impossible.

Originally Posted by pipeclay

The hard part is deciding when to stop chasing the impossible.

Thanks pipeclay - have edited the original post to make my question clearer.

Will have another go at getting something perfectly centred, will turn a cylinder in 3 jaw then try and centre it in 4 jaw.

Bill

If the material has been turned I can usually get within .01mm in a short time.
If it's unmachined and I'm chasing my tail I will just try to match the opposing jaws.

Originally Posted by steamingbill

Did 2 jobs on 4 jaw chuck.

Used dial gauge to centre the cylindrical pieces. A liitle confusing but managed ok.

Was fluttering +/- .0005 ie completely within two 1/1000th lines - decided that was good enough

Should I be able to get the needle on the gauge rock solid with absolutely no movement at all showing on the gauge when the piece is securely held in the jaws ?

Bill

Sorry Bill, I didn't answer your question very well. I meant that it takes a disproportionate amount of time to chase down the last quiver of the needle and it's rarely worth it. I usually find I lose that hard-won perfection when I do a final tighten anyway.

Here's a fun exercise: Chuck up a turned bar in your 4 jaw with a fair bit of stick-out, say 120mm or more. With your indicator as close to the chuck as possible, centre the work. Now move your indicator near the end of the bar. I predict you will find a fair bit of run out. If you want the work aligned with the spindle axis you need to centre it in two places.

What I do is get it close near the chuck, with the jaws just snug. Then move the indicator along to the end and find the spot on the work that's furthest from me. I just lift the indicator plunger away while I tap the work towards me with a soft hammer, then release to see how far it moved. Go back and forth between the two ends, increasing the jaw tension each time till you're happy.

You will usually find that the deeper the work is gripped in the jaws, the less adjustment you can get at the far end. It may be worth sacrificing some grip depth to get better alignment.

So there's no point spending ages on centering if it's cocked.

Today is my lucky day.

While working on my lifting trailer jack as mentioned in my earlier thread, I dislodged the boom from where I had it propped up on the hay lifting section. The top mounting pin for the jack was sticking out from removing the jack. The pin hit me on the head when the boom fell. It hit the front of my head just inside the hairline and glanced off. It hurt for a minute or two and left a sizable lump. If the pin had hit me full on the top of my head, I imagine I would be in hospital now waiting for surgery. I do tend to have a pretty hard head tho.

Dean

now that is close. glad you are ok. go careful.

I'm working on a mid 30s Hudson at the moment. One of the many jobs that need to be done is to make a new clutch throwout shaft which has a couple of cast components secured to it with taper pins. http://www.woodworkforums.com/showthread.php?t=181851

On trial fitting the components to the new shaft it was apparent that the taper pins are not drilled on centre (which is how I made the shaft) they are offset by 1/32". Its all blindingly obvious at that point of course, the offsets are for production purposes, ie to make sure that the components can only be fitted correctly oriented to one another.
Something to store in the memory banks.

The pins are offset to the left.
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Today I learnt that when using telescopic bore gauges to measure a near finished part on the lathe, be careful not to push it in too far! In a moment of distraction, I pushed it through to the open end and it sprung out and locked itself in the part. Try as I may, I couldn't lever it out. Had to remove the part from the 3 jaw and loose concentricity!

Simon

Originally Posted by simonl

Today I learnt that when using telescopic bore gauges to measure a near finished part on the lathe, be careful not to push it in too far! In a moment of distraction, I pushed it through to the open end and it sprung out and locked itself in the part. Try as I may, I couldn't lever it out. Had to remove the part from the 3 jaw and loose concentricity!

Simon

Damn that sounds frustrating. In fact, it sounds like something I would get caught out with.

Dean

Ha! well, with every stuff up comes a new learning experience. Turns out that I was using an incorrect technique with the gauges anyway. After watching a few youtube vids I learnt the correct way.

Simon

I learnt yesteday that small front wheel drive ute and a ditch dont mix

Originally Posted by welder

I learnt yesteday that small front wheel drive ute and a ditch dont mix

would it have made any difference if it was rear wheel drive???...looks like the rear wheel/s is off the ground

Today I learnt not to accept the controls from my sons remote controlled quad copter after he flew it so far away that it just looked like a dot in the sky.

After I told him (several times) to bring it in a bit closer because it was too far away and too high, he finally realised he was out of his depth and threw the controls to me. I was left holding the baby to say the least and I too was way out of my depth, no longer able to tell if it was coming or going……. definitely going in hind site!

Now it's all my fault

Simon

Yep been there and done that, (Kids shifting the blame), but if you found it, and it still works, or if he ends up with another, and gets in a similar pickle, you could try to make a right turn say. If when attempting to turn right, you find that it turns left, you then know that it is returning toward you.
The one bright spot on the far horizon may be that one day he will have kids of his own, and if you are fortunate to still be around, you will be able to tell his kids what he was like, and also remind him of these events when he complains about his kids doing similar stuff. The longer you have to wait for this the more you will enjoy it

Hi Ropetangler,

Yes, at the time I was very annoyed. It was his BD present from Saturday! Anyway, try as I may to steer it back, the wind kept changing it's direction. It has white LED's on the front 2 legs and red/blue at the rear. In the end all I could use to steer were the faint colour of the LED's, trying to keep the white in view and go forward but the red/blue kept showing up pushing it further away. In the end, they all started flashing which indicates either low power or low signal from the transmitter. Flashbacks from the Apollo 13 movie came to mind Except they all made it back!

In the end I just cut the power. Being made of EPO foam, it floats at a survivable rate even with no power. When I drop the kids off at school, Ill do the walk of shame and door knock. A compass bearing of roughly 60 deg Mag gives me a rough direction and looking at google maps/where is , I will target about 4 homes that I think it may have landed in. The houses here are all 3 -5 acre lots and so lots of backyard to fall into (I hope!)

It's funny, there was no wind to speak of at the time but I fear he had it so high that it caught the jet stream!

I'm going to buy myself a quad copter, but I'll buy an optional GPS module. If you get lost, you push a button and it finds it's way home, or to where it took off from.

Simon