Thread: Runouts on machinery

Originally Posted by Michael G

Having once mixed jaws on a chuck, I can say that the difference is many times greater than the improvement you are chasing (it would be roughly a 1/3 of the pitch of the scroll)

Certainly not what I meant.

Three tests

Jaws 123 Slots 123
Jaws 123 Slots 312
Jaws 123 Slots 231

NOT Jaws 132 or similar

Given that Bob's jaws/slots are numbered I'd think it unlikely to see an improvement. Maybe he'll get lucky.

Originally Posted by Stustoys

Certainly not what I meant.

Three tests

Jaws 123 Slots 123
Jaws 123 Slots 312
Jaws 123 Slots 231

NOT Jaws 132 or similar

Given that Bob's jaws/slots are numbered I'd think it unlikely to see an improvement. Maybe he'll get lucky.

Yep - that's my thinking as well.

I can't remember which of my chucks has this, but one of the chucks has the numbers crossed out and renumbered.

I'd would have already tried this out but my knee is giving me so much gip this morning I can't stand for more than about a minute and even the short distance walking down to the shed is too painful.

Originally Posted by BobL

Yep - that's my thinking as well.

I can't remember which of my chucks has this, but one of the chucks has the numbers crossed out and renumbered.

I'd would have already tried this out but my knee is giving me so much gip this morning I can't stand for more than about a minute and even the short distance walking down to the shed is too painful.

It did sound like we were on the same page.

Well thats a new one lol. Do the chuck and jaws have serial numbers as well?

Time for some new ones? My knees are the opposite. They take awhile to get moving but then they are ok. Hope they improve.

Saw the doc about the knee - he thinks its osteo and was going to refer me for a knee replacement!!!! - I said hang on what about trying a few other things first.
So
Another cortisone needle in teh knee, this time with a bit more cortisone - and they will aspirate some fluid for analysis so they can do a positive check for gout - makes sense, so why want this done first up"
I've already had two ultrasounds and a bone scan with all 3 recommending a standard X-ray - once again why hasn't this happened?? So doc signed me up for that.
Some meds for the pain and possible gout.
A referral to an arthritis specialist.

Inspired by all this I hobbled down to teh shed and did all these measurements

I cleaned the jaws and the scroll on the 5" and tested the original jaw positions, and then rotated the jaw positions as per Stu's suggestion - results in red in table below.
I'm pretty happy about the improvement @ jaw position 1
I'm going to try this on the 4" as this is the one with the numbers stamped into the chuck body crossed out and renumbered!
Thanks for the tip ST

Screen Shot 2018-08-01 at 1.39.20 pm.png

Now this was something AB suggested - measure the height variation across the Hercus O mill table.

The gauge is attached to the vertical dovetail and I drive the table into various positions along and across the table and record the height at various points.
I only measured 150 mm either side of centre as this was the limit of drive I could reach without re-referrencing the gauge.
The mill table is not that much bigger than this anyway
The RHS of the table has a few small marks/divots that might explain the 0.03mm height at the 150 mm mark.
the further away from centre the more divots there appear to be.
While divot are holes so they should measure as negative they also can raise the height on either sides of the holes. I could see the gauge jumping around in this region so had to take a ball park of the measurements.

There are three sets of measurements - one along a line of the middle length of the table(middle - red line) , and two (inner and outer) on either side of that line nearer the edge of the table.
I would be interested to hear what others have in this region of their mills.

Screen Shot 2018-08-01 at 1.36.34 pm.png

This has sucked me in, when I get home I am going to get in the shed and measure the runout on my machines.
Some years ago I did the swap around of the jaws on my lathe 3 jaw chuck to achieve a better result, don't recall but I think I got it to .002".

Hi Bob, in the latest MEW, there is an article on regrinding lathe chuck jaws, using a Dremel. Can photocopy and snailmail it, if you can't get hold of a copy. Can't scan and email.
Kryn

Originally Posted by KBs PensNmore

Hi Bob, in the latest MEW, there is an article on regrinding lathe chuck jaws, using a Dremel. Can photocopy and snailmail it, if you can't get hold of a copy. Can't scan and email.
Kryn

Thanks Kryn. I might just leave it for now given its well within the expected ball park for a 5" 3jaw.

My lathe is a cheap Chinese AL320G that I have had for 8 years, and I did a fair bit of tweeking and adjusting in the first couple of years. The runout at the spindle nose is >.0005", the original 3 jaw chuck using a 10mm milling cutter shaft is .0015", pretty happy with that.
The little Optimum mill I have had for about 3 years, the runout at the spindle nose is .001", with an ER32 chuck it was .002", looked like .001" for each so I turned the MT3 mounting 180deg. and almost eliminated the runout, the needle does move but not measurable with my instruments.
I did the same test as Bob on the table of the mill, from centre up to 200mm to the right there is a .001" rise, 200mm to the left, no variation, front to back no variation.
My drill press is a different story, the spindle runout is .004", and with the original chuck it is .020", this is noticeable as when you use it, you can be see it wobble, looks like a better quality chuck would be in order.
Please excuse the mixed measurements, most of my dial gauges and other instruments date back about 45years, some quite a bit more, so they are in inches.

Thanks for the response.

Originally Posted by BRADFORD

My lathe is a cheap Chinese AL320G that I have had for 8 years, and I did a fair bit of tweeking and adjusting in the first couple of years. The runout at the spindle nose is >.0005", ....

I assume you mean <0.0005"

Originally Posted by BobL

Thanks for the response.

I assume you mean <0.0005"

Yes
I notice your post was at 3:16 am, was your knee keeping you awake?

Originally Posted by BRADFORD

Yes
I notice your post was at 3:16 am, was your knee keeping you awake?

Yes, but it was indirect. I went to bed at at around 8:30 pm last night and because there was very little knee pain I fell asleep almost immediately and woke up at about 2:30am so thats ~6 hours of sound sleep which is way more than I have most nights. I then stayed awaked till about 4am and went back to bed and dozed on and off till about 7am. I am supposed to be resting for 48 hours (ha) so after a cup of tea I went back to bed until now.

SWMBO has gone shopping so I went down to the shed for some more measurements (in blue font).

This time I did the outside jaws of the 5" (but only the innermost section of the jaw) using the same 10 mm milling bit.
Considerably worse than the inside set of jaws.

Also I cleaned the 4" 3 jaw and repeated the measurement and other two jaw positions.
Looks OK to me.

Looks like it pays to keep the jaws and scrolls clean and try the other jaw positions.

Screen Shot 2018-08-02 at 2.23.29 pm.png

Originally Posted by caskwarrior

What exactly was the runout figure on the 4 jaw, just the body? .

0.08 mm

Originally Posted by shedhappens

One thing to remember when checking spindle runout is that a taper has 2 ends, if the back end is out it will also produce run out in whatever is sticking out the front.

Now here is something interesting for drill press chucks.

For the following MT 3 arbor chucks; (KL - keyless)
First number is the RO (in mm) on the MT3 drill press, second number is the same chuck but measured on the lathe
KL1 0.035 , 0.04
KL2 0.30 , 0.16

Now MT 2 arbor chucks, so this includes an MT2 adapter
KL1 0.55 , 0.32
KL2 0.45 , 0.18
Keyed 0.56 0.45

any idea what might be going on - something related to what SH said maybe?

Roberto,

When you take these measurements is it a one off affair or are you removing the chuck from the spindle and reinstalling it to try to obtain the lowest reading? Often run out can work in your favour.

I had just been up the shed fooling around with a 0.01mm indicator and my little, pretty accurate Sherline three jaw which requires a 2-3 Morse sleeve to fit the Hercus. My first reading was underwhelming, 0.03mm TIR. I popped it out of the spindle and reinstalled it and remeasured the runout, 0.01. The Sherline's 2 Morse arbor is home made with built in run out but when combined with the 0.007mm spindle TIR and probable inaccuracy in the sleeve, miracles can happen.

IMG_20180802_152401569 (Large).jpg

Bob.

Originally Posted by Anorak Bob

Roberto,

When you take these measurements is it a one off affair or are you removing the chuck from the spindle and reinstalling it to try to obtain the lowest reading? Often run out can work in your favour.

Thanks for your input AB.

What you say about hunting around for a reduced RO location on MT3 chucks is a good point and I have thought about it but mostly I wanted to simulate what I have been doing in practice
- put on blue and white apron
- remove or replace chuck
- keep working
Now I see I should for a start get a new apron.

The only time I remove the chuck on the DP is when I sometimes use the MT3 drill bits.
I will explore this one with the better MT3 - if I find a better spot I guess I can then mark these on the spindle and chuck itself so that it goes back the same orientation every time