San Ou K72 – 200 4Jaw Chuck Sitrep

[MadMikeParticipant @madmike]

[MadMikeParticipant @madmike]

You may recall that last week i sought opinions on the San Ou Independent 4 Jaw Chuck for my Myford 254S.

Well having got fed up with looking for a D1-3 mounted chuck, I decided to buy the San Ou K72-200 chuck. So here is what the guys in the NCIS TV series call a Sitrep (I know nobody except me watches it. LOL)

Order placed via Ebay very late on Sunday. By late I mean about 11:40pm.

Order acknowledged almost instantly

Monday I received a text and e-mail to tell me that the chuck would be delivered pm on Wednesday.

At 12:45 today, Wednesday the nice Royal mail man arrived, warned me that it was heavy and insisted upon taking into my garage for me.

So the package was well presented. Upon opening I determined that it was packed in a heavy duty purpose made box. The chuck was fitted into a pair of purpose made poystyrene mouldings within the box and was wrapped in an oiled paper material. the chuck key and 4 M10 capscrews were also within the packing.

Now for the chuck itself…….Well the ebay photo's all look like studio shots which make the chuck look shiny and well finished. They do not lie. it is frankly a lovely looking product. Dimensionally It is precisely the sizes shown on their data sheet which appears on most sites selling the chucks. Of major concern of course was the recess in the back face which is critical for centralising the chuck body on the back plate register. It was within .002 of the size on their data sheet. There were no burrs or sharp/ragged edges anywhere on the chuck body, jaws or the tightening screws.

I turned the back plate, bought from Chronos and also a very well made product, and fitted the chuck.You can't see the join….LOL.

Now the acid test. I put a 2 inch diameter steel in the jaws and then adjusted it until it was central on the spindle axis and then put a DTI on it and rotated the chuck. At a distance of 2.5 inches from the chuck face there was a deviation of .003 inch in the dial needle. Then I reduced the diameter of the steel with a roughing cut of .080 inch followed by a finishing cut of .005 inch. This time no run out was recorded.

My conclusion? Well time will tell but at a mere £87.26 including VAT and delivery I am both impressed and delighted in equal measure.

Sorry to have taken so much space but I hope that this will prove useful to anybody contemplating buying this product.

[Pete.Participant @pete-2]

Then I reduced the diameter of the steel with a roughing cut of .080 inch followed by a finishing cut of .005 inch. This time no run out was recorded.

What does this procedure tell you about the chuck?

[Roger Williams 2Participant @rogerwilliams2]

Im lost !?. Must be missing something here, its an independant 4 jaw, so what you have written tell us nothing …..sorry. Unless you mean the chuck is a 4 jaw self centreing one ????.

[Clive FosterParticipant @clivefoster55965]

Pete

The cut test is basically grip verification.

Ensures that it holds well enough for the work you do.

If the jaw gripping faces aren't exactly parallel the chuck won't hold well. Usually a thing with older chucks due to bell mouthing and wear in the guides. The combination lets the jaw tilt so only a small part actually grips properly.

Back in the day affordable (cheap) chuck manufacturing standards were often a bit casual with excessive jaw to slide guide clearances, variations in jaw slot depth, variations in guide thicknesses and gripping faces not quite parallel to the jaw guides. Generally nothing huge although I have encountered one four jaw chuck where variations were sufficient that you had to put the jaws in the proper slots or you'd be left with one that couldn't be fitted. But it was cheap, really really cheap, and the actual jaw alignments were good so it worked well. Far as I can see that problem has gone away with better manufacturing standards on even inexpensive import chucks.

These issues were why received wisdom then was that cheaping out on a 4 jaw was safer than on a 3 jaw as 4 jaw issues can mostly be worked round. Even a less than wonderful new four jaw being considerably better than a clapped out old one.

The other check is that it holds diameter correctly on a long cut and that a centre hole drilled with the job barely projecting from the jaws aligns well with the tailstock centre when pulled out well down the bed. Basically verifying that it holds parallel to the bed. A very severe test of both chuck and machine alignment. Perfection is unlikely! Assuming the mounting plate has been skimmed true in situ before fitting the chuck significant errors are unlikely as it would mean the chuck has been machined on the slant with the jaw guides not parallel to the back face. Nothing I've ever seen or heard of outside normal tolerances but I'm sure someone somewhere has encountered a Friday Afternoon job that was made seriously out of true.

Always worth checking the front face runs true as its often used to set work against. Not something that is generally checked and toleranced but its generally very good although I have seen some that were a bit out of flat. Thou or three maybe so a job could theoretically rock as the jaws were tightened.

These days the checks are about ensuring that you haven't got a Friday Afternoon job. Obviously you have to consider price performance ratio. Perfectly usable at a sensible price now seems to be given but near perfection over a long life costs £££. Seriously costs £££.

Clive

[MadMikeParticipant @madmike]

Oh dear I am sure that I explained my actions simply. However, let me clarify things for you: –

(1) The chuck is a 200mm independent four jaw chuck.

(2) The initial "static" test was to determine the accuracy of the chuck during the setting up process, and to determine that there were no strange results occuring due to any mechanical faults with the chuck.

(3) The cutting test was to determine that the chuck produced the accuracy I expected/wanted under load.

(4) The chuck performed exactly as I wanted.

(5) What have I written to tell you. Well following on from the lack of any detailed personal experiences when I raised the question of the quality of the San Ou chucks I thought that it might be useful for other "engineers", real or perceived, if they are considering such a purchase. After all £87.26 including VAT and delivery might be considered expensive by some, whereas I wanted to determine whether such a low cost product was worth purchasing. It is most certainly great value at the price.

My conclusion after all this? Well after those replies I wouldn't bother again.

Edit: I have just seen Clives response. Thank you for explaining that for those that clearly did not understand what was going on. I assumed, wrongly that they would understand what was intended……I was wrong about their powers of understanding. You are of course NOT included in my reference to "those replies".

Edited By MadMike on 22/07/2021 09:28:45

[old martParticipant @oldmart]

What you should have done was to have reversed the turned bar in the chuck, set it true at the jaws and then checked the runout at the far end of the turned section.

These inexpensive chucks are ideal for home shop use.

[Howard LewisParticipant @howardlewis46836]

Take heart Mike!

It is always easier to be negative than constructive.

You gave a good description of the chuck and its packaging, so that potential purchasers would have a better idea of what they were likely to get.

The usual way to silence the smart arse nay sayers is to say "O K. If your way is better, show me"

Years ago the tyre company that supplied / leased the tyres that we used on our buses and coaches were going to "improve" their tyre fitter arrangements. A meeting between all the Engineering Superintendents, Area Engineers and two of their reps was told that a wheel could be changed, using manual equipment in ten minutes, from start to finish.

Almost all of us produced a £5 note and said "We don't believe you. These say that you can't. Show us"

NO takers!

But at some time, we had all done the job, and knew what was involved!

Howard

[Nick WheelerParticipant @nickwheeler]

Posted by Howard Lewis on 22/07/2021 09:49:02:

Years ago the tyre company that supplied / leased the tyres that we used on our buses and coaches were going to "improve" their tyre fitter arrangements. A meeting between all the Engineering Superintendents, Area Engineers and two of their reps was told that a wheel could be changed, using manual equipment in ten minutes, from start to finish.

Almost all of us produced a £5 note and said "We don't believe you. These say that you can't. Show us"

NO takers!

But at some time, we had all done the job, and knew what was involved!

I saw our workshop manager change all six tyres, using only hand tools, on a 12 ton recovery truck in an hour without even getting dirty. He'd had a lot of practice as a mobile fitter, where you don't want to be on the hard shoulder of a motorway any longer than is absolutely necessary.

[Pete RimmerParticipant @peterimmer30576]

I think that the feedback on general quality and finish is as important as anything so thanks for that Mike. It's true that any part held firmly and turned should have no runout but it could be out of round, tapered or all kinds of shapes if the jaw faces were not parallel and lkwed the part to Rick in the jaws whilst turning, so there is some significance there.

Incidentally whilst the conce tricity of the rear register is an indication of the general quality it is in no way critical to the mounting of the chuck body concentric to the backplate. You can achieve that with no register at all by using a DTI to dial the chuck in before tightening the bolts. What is most critical is the parallelism of the chuck face to the rear mounting face. You can't adjust that out.

[Andrew TinsleyParticipant @andrewtinsley63637]

Thank you Mike, for your review of the 4 jaw San Ou chuck. They do appear to be excellent value for money. I purchased a smaller 3 jaw chuck from Arc and that was just excellent all round. I checked it out and found that it didn't lack when compared to a PB chuck. The only difference that I could find was that the scroll action was not quite as smooth as the PB chuck.

It might be worth saying that the chuck was marked as an ARC product, but I seem to recall Ketan saying that his Chinese chucks were San OU sourced. The other thing that he commented on was that San Ou would produce more or less the same chuck but at different quality levels and prices. So you cannot assume that different suppliers are selling the same quality San Ou chuck.

I hope I have not misquoted Ketan on the subject.

Regards,

Andrew.

[peak4Participant @peak4]

Mike, I'm not in the market for one at the moment, but from where did you source your new toy?
Pretty good delivery times, so presumably not from China.
Thanks
Bill

[Brian WoodParticipant @brianwood45127]

Hello Mike,

I'm with Howard Lewis in his observations but just out of interest since you don't mention it in your analysis, do these chucks come with hard jaws?

Regards

Brian

[MadMikeParticipant @madmike]

Info for peak4 and Brian Wood.

Bill, the dealer that I bought from has the ebay name, matyebeb. the parcel dispatch was from Dunstable.

Brian the jaws are inded hard.

[PeroParticipant @pero]

Hi Mike

I have three San Ou ( aka Sanou ) chucks but didn't respond to your original query as mine have yet to be installed and tested.

The three I have are all six jaw chucks: a 4" ( actually 110 mm ) extended jaw chuck and a 5" and 10" chuck with 'normal' hard jaws. The 10" may prove a bit of a struggle with the ML7 but I will give it a whirl.

As has been noted above the external finish is very good and the fit of the jaws is excellent.

I did find a video on the internet prior to purchasing mine. It was by a model engineer reviewing a new chuck, including a full breakdown and service and a modification to the rear of the chuck to allow it to be fitted closer to the spindle nose on his particular lathe.

His key recommendation was that prior to use it was advisable to dismantle and thoroughly clean the chuck to remove any residual grit that might be present and then re-lubricate before reassembling.

I am not sure how old the video was or whether improvements to manufacturing ( they are getting better all the time ) have negated this suggestion. Probably a good idea of there is any indication of grittiness in the jaw or scroll action.

Pero

[Kiwi BlokeParticipant @kiwibloke62605]

As far as I can see, the reported 'test' doesn't really tell us very much at all, except that the chuck grips OK. The jaws might, however, grip on an axis that isn't parallel to the spindle's axis.

Here's a suggestion how such a lack of axial alignment may be detected. Start with a bar that is known to be round. Hold in the chuck, and clock for minimum eccentricity. Turn a constant diameter for, say, 4 inches. Clock the far end to check for neglegible eccentricity, otherwise, if there is, all bets are off. Slacken two adjacent jaws just enough to be able to rotate the bar, and rotate it 180 degrees. Re-tighten the two slackened jaws.

Clock the turned bar for eccentricity as near to the chuck as possible. It's likely, even with a 'good' chuck, that the loosening-tightening cycle results in a little eccentricity. Clock and adjust for minimum eccentricity as near to the chuck as possible. Now, the test of jaw alignment – clock the bar as far as poss away from the chuck.

Of course, you can get the same info with a test bar, but we don't all have one, do we?

 

Edited By Kiwi Bloke on 23/07/2021 07:32:34

[JasonBModerator @jasonb]

Posted by Andrew Tinsley on 22/07/2021 10:54:37:

It might be worth saying that the chuck was marked as an ARC product, but I seem to recall Ketan saying that his Chinese chucks were San OU sourced. The other thing that he commented on was that San Ou would produce more or less the same chuck but at different quality levels and prices. So you cannot assume that different suppliers are selling the same quality San Ou chuck.

I hope I have not misquoted Ketan on the subject.

That's about right.

So what we still don't really know is if the cheaper chuck was to a similar quality level as those sold by the regular ME suppliers. The recess is said to be 0.002 off, assume inches Arc's ones may be closer to spec. Now before you all say it does not matter worth noting that ARC sell a lot of theirs for Direct spindle flange mounting so you don't what to be clocking a chuck in every time you change it over as can be done on a backplate mount one when first mounted so something to bear in mind if you have direct mount, even more so if it were 0.002" smaller than the register on the spindle

I would also be interested to know if the 0.003" runout at a distance from the chuck was just the bar or whether it was the gripping surface of he jaws throwing it off. I suspect just the bar or a bit of droop as jaws were adjusted but trying with a known bar with equal sitickout inside and outside chuck would give a better idea of it's spec.

Another test would be to put the Dti on the face of the chuck to see how true that runs as work is often pushed back against that, it would show if those ground surfaces are parallel.

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