Studer RHU 450 from the 1960s - Page 6
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  1. #101
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    My only suggestion is to figure out how far the table travels out to the extreme. From what we saw as far as the galling on the ways out there you could extend the oil groves a little more on a diagonal line. That's why you need to figure out the extreme travel so the table doesn't feed out over the base and you loose way oil pressure that's created now. Just a idea so the machine doesn't gall again. Be sure to vacuum the chips and blow out the oil holes / lines and then see if you can get way oil pumping onto the ways while the table is off. We already discussed stoning the the last time with mineral spirits lightly and running the round edge of the stone in the oil grooves.

    Then was it good and wipe with a white cloth until you don't get a black or gray residue on the rag then wipe with your hand to be sure ll the crud is gone(you can't feel crud with a rag), then position the table over the bed and just before letting down use a squirt oil can and squirt some way oil or the special hdy. way oil. Then cycle the table to the extreme for a couple of hours, Also observe the oil on the exposed ways and see if a puddle is pushed in front of the table. It should. Looks super...Rich
    Last edited by Richard King; 02-04-2018 at 03:23 AM.

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  3. #102
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    Hi Richard,

    I didn't modify the oil grooves, but other than this I followed your instructions closely. Here were the ways after cleaning off the ink and stoning:



    And here are the ends with the machine in operation but with the end way covers removed:





    A few observations:

    - The machine had the wrong oil in it. I know this because before changing the oil the hydraulic pressure was 5 bar, and oil dripped from the tell-tale. After changing the oil, the hydraulic pressure is 7 bar (just like the manual says it should be) and oil flows from the tell-tale in a steady stream.

    - I ran it for a couple of hours with no weight on the table, then added the swivel table and work head and ran it for a few more hours. The oil is flowing nicely to both ends, the oil grooves are filled, and there is a puddle ahead of the moving table.

    - For a little while after startup, the oil coming off the ends had some black sediment (carbon?) which settled to the bottom of the catch basin.

    - I can now run the speed incredibly slow (1 inch per minute!) and the table motion is completely steady and even. Before it would be "jumpy" at speeds ten times faster than this.

    Richard, thank you so much for your help and guidance with this. Now I have to learn some basic cylindrical grinding!

    Cheers,
    Bruce

    PS: when the time comes to sort out the tailstock alignment I will restart this thread.
    Last edited by ballen; 02-04-2018 at 02:23 PM.

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  5. #103
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    My pleasure...Your Welcome :-) Just keep an eye on the places that were galled. So many machines can be improved with just a square cut and it looks like you proved it to our readers. Next time I teach in Germany I hope we can meet and you can buy me a beer ..lol The easiest way to do the head and tail-stock is to scrape the Tail-stock first as it is no doubt lower then the head-stock. Then bring the headstock down until it is a little lower then the tail-stock so as the TS wears it get better.

    Find yourself some test bars that fit in the stocks tapers that have the same size OD.

    Thanks Ballen for asking me to help. I really enjoyed it. Talk to you later. Rich

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    Hi Richard,

    Quote Originally Posted by Richard King View Post
    Just keep an eye on the places that were galled.
    Will do.

    Next time I teach in Germany I hope we can meet and you can buy me a beer.
    I will do this, and would also like to take your class.

    The easiest way to do the head and tail-stock is to scrape the Tail-stock first as it is no doubt lower then the head-stock. Then bring the headstock down until it is a little lower then the tail-stock so as the TS wears it get better.
    In my case the TS is *higher* than the workhead (WH). But I will study both the TS and the WH very carefully before taking any action. Then come back here.

    Find yourself some test bars that fit in the stocks tapers that have the same size OD.
    One of my first grinding projects is to make a (shortened) MT5 test bar that fits the WH. I already have an MT2 bar that fits the TS.

    Thanks again. One of these days I hope to meet you in person as a face-to-face student.
    Cheers,
    Bruce

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  8. #105
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    Hi Richard,

    Quote Originally Posted by Richard King View Post
    Find yourself some test bars that fit in the stocks tapers that have the same size OD.
    I've ordered material for making two test bars. It's going to be my first exercise in cylindrical grinding. I'll rough out the tapers on the lathe then finish the taper and cylinder on the grinder.

    Meanwhile I have a question for you. I've run the machine for 6 or 8 hours now, just exercising the hydraulics and "grinding air" to understand the controls. Everything is working well, and my geometric checks don't indicate any loss of accuracy or alignment. And there is absolutely no sign of stick-slip. So all is good.

    But if I look very closely in the visible oil grooves, I can see some little "sparkles" which must be some tiny flecks of metal that have come off the ways. I suppose this is because after I square cut them, there are at least some new high spots that are coming into contact and lapping each other smooth. Or perhaps this is just scraping residue working its way out from the pores of the cast iron, from the inner surfaces of the pockets. I'm not sure.

    My question is, should I just ignore this? Or should I remove the table and give everything a good cleaning and flush to get rid of that stuff? I think the design of the oil grooves will eventually cause the little sparkles to be flushed out, but it might take a long long time because of the oil groove design.

    Cheers,
    Bruce

  9. #106
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    Bruce,
    Probably, it helps if you could more or less quantify the size of such "sparkles". I guess that some of them could be graphite that got exposed by the scraping. I bet there are simple tricks to distinguish between iron and graphite. With my complicate mind I'd take up some oil with sparkles with a syringe or something similar, deposit it on filter or blotting paper, wash with solvents to remove the oil, and add some acidic substance (likely, a few drops of lemon juice should be enough): if it's iron, it should rust.
    But, as I said, there must be something simpler (caveat: graphite powder is also attracted by a magnetic field).

    Paolo

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    Hi Paolo,

    Quote Originally Posted by Paolo_MD View Post
    Probably, it helps if you could more or less quantify the size of such "sparkles".
    Let's see what Richard says, this may be normal and nothing to worry about. But to satisfy our curiosity I'll put a drop of oil under a microscope and see if I can locate one of these sparkles. A nice way to measure the size is comparing it to the width of a piece of hair laid out on the slide. Normally a hair is about 50 microns wide (0.002") but varies quite a bit from person to person. So you first calibrate the hair with a micrometer or calipers. I am guessing that the sparkles are perhaps 10 microns (0.0004") in size, but that's just a guess.

    Cheers,
    Bruce

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    I have a further question for the experts: how to make an oil "tell-tale". This is to show that oil is flowing to the table ways on the grinder. There is a copper tube, about 6mm = 1/4" diameter, which comes up at the right side of the machine as shown here. You can see this copper tube in my Avatar photo above. Oil comes out of the end of this tube (about 40 ml/minute) to indicate that the oiling system is working properly.




    The problem is that this tube is hidden in darkness under a way cover. The manuals for some versions of my machine show an oil-glass around this location, but it's missing from my machine. It looks from the outside like a traditional oil-glass, about 1 inch/25mm in diameter. My question is, what should I put inside that? If I just add an oil glass, I won't be able to see inside at all to know what's happening in the copper pipe. It's too dark in there.

    One clue is that there is a small hole drilled into the copper tube. So I was thinking, perhaps the way this is supposed to work is that I should install the oil glass with the bottom edge lined up with that hole. Then add a transparent plastic tube to the end of the copper tube, which comes up to above the oil glass. This way, if oil is flowing it will fill the plastic tube. But if no oil is flowing it will drain from the little hole in the copper tube and the level in the plastic tube will drop to the bottom of the sight glass. If the plastic tube is right next to the oil eye, I should be able to see the oil level in the plastic tube because some light will come in through the sight glass from outside. Here's a drawing showing this idea:



    Is this the right way to do it? Or is there another standard solution?
    Last edited by ballen; 02-08-2018 at 06:48 AM.

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    Bruce,
    Just a naive idea: what about installing the spy glass and a LED light shining some light on the copper tube in the area of the small hole?

    Paolo

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    on my lathe oil is squirting against a sight glass. you can see it well.

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  15. #111
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    Ballen...I love your new Icon.. :-) You must have a lot of pride in what you have accomplished. I know I am pleased as punch :-) and have told Charles Blair he should make this a sticky.

    It's 1 AM here...will write more tomorrow. Super Job my friend. :-) Rich

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    Paolo: I thought about adding an LED, but my preference is for the simplest possible solution. So I'd like to reproduce what Studer did in the 1960s with similar machines.


    Dian: once I get the sight glass in place, I'll try installing a plastic tube to squirt against the sight glass. Perhaps that's all that's needed. But why the air hole in the copper pipe?


    Rich: yeah, I am happy with how this has worked out. Thanks again for the great support!

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    I've added a visual indicator as suggested by Dian to show the oil flow to the ways. This uses a G 3/4 threaded plastic window.

    First step was to make a hole and thread it. Because I don't have a magnetic drill or portable mill, I had to do this with a hand drill, through about 20mm (3/4") of cast iron. After a failed attempt with an HSs drill, I bought this carbide tipped coring bit which worked very well.





    After threading the hole and putting the plastic window in place, I added a short plastic tube to the copper tell-tale tube. The open end of this tube "pushes" on the inside of the plastic window:





    Here is how it looks when no oil is flowing:



    and here is with oil flow:



    I think that's it for machine modifications and repair for now.

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  19. #114
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    I made one further improvement to the oil flow window described above. I modified a brass 3/4" fitting as shown here



    This goes into the threaded hole on the INSIDE of the grinder, behind the oil window, with the small hole at the bottom. The oil feed tube comes in the top. This fitting ensure that when oil is flowing, the level is at the middle of the sight glass, making it easier to see and verify.

    Now that I have finished the prep work, it's time to start learning to grind. The wheel I got with the grinder is this one:



    It's 300mm (12") diameter, 30mm (1 1/4") wide, with a 127mm (5") center hole. I am not experienced at reading the codes, but I think 81A is aluminum oxide, 80 is the grain, I don't know what the -4 means, G is the hardness (on the softer side) 13 is a very open bond. M is not a bond type that I could identify, perhaps the V means vitrified bond. I balanced the wheel before dressing it, but need to rebalance it again after dressing.

    I filled the grinder with coolant, the same synthetic stuff that I use on my surface grinder, about a 5% strength.

    I don't yet have a proper set of grinding dogs (have to make those) but decided to have a go with a lathe dog and a piece of 16mm (5/8") random steel stock from the scrap drawer. This is not hardened.



    I worked at getting it cylindrical. The first attempt was out 16 microns in diameter (6 tenths) over 100mm (4"). After shifting the table it was 5 microns (2 tenths). I'll try again later today to see if I can get it down under a micron.

    The finish is not as good as I would like



    but I will experiment with feeds and speeds today and see if I can make it better. Buck, Cash: I would be grateful for advice and tips on technique. I am guessing that I should be able to get a mirror finish or near mirror finish with this wheel, provided that I get the dress and feed and work rotation-speed right.

    Here is a short video of the machine in operation. I may need to replace the coolant nozzle with something better. I have some modern plastic nozzles that I got for my surface grinder, I may convert it to use one of those.



    Cheers,
    Bruce

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  21. #115
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    What did you figure out about the "air hole" in the line going to the V? Are you sure it's just not a leak hole?

    Broken, cracked line?

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    Hi Richard,

    Quote Originally Posted by Richard King View Post
    What did you figure out about the "air hole" in the line going to the V?
    My diagram must not have been clear: this tube does not go to or come from the V.

    There are 3 copper tubes that come up from the hydraulic oil pump. The first tube goes to the flat ways. The second tube goes to the V ways. The third tube is the one which is visible in my photos. This third tube doesn't go anywhere, it just drains back to the sump. In fact I have re-routed this third line so that it goes to the oil eye that I show in my photos.

    Only this third line has a little air hole. The other two lines going to the ways don't have such holes. The hole is clearly deliberate and not accidental. But now that I have thought about it, I think that I understand its purpose.

    This third tube is a tell-tale: it was designed to drip into the oil collection "basket" at the right end of the machine. The designers were concerned that the oil in this basket might "back up" and cover the end of the tube. If you then shut off the machine, the oil in that basket would "siphon" back down into the pump, pulling with it whatever grit and crud had fallen into the basket and were suspended in the oil.

    So I think the air hole is there to prevent oil from siphoning backwards from the collection "basket" to the region around the output of the pump, where it might get redistributed under the ways with whatever grit it is carrying. Does that make sense to you?

    Cheers,
    Bruce

    PS: I am using a piece of my cast iron practice bar to make a holder for a sensitive (1 micron/division, Tesa) dial indicator, which will enable me to set angles on the cylindrical grinder using gage blocks. But there's still enough left for scraping practice!
    Last edited by ballen; 02-13-2018 at 08:31 AM.

  23. #117
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    Hi Ballen,

    Saw this thread just now, I´m impressed with the work you´ve accomplished. Looks really nice, and remembering what you´ve done and shown previously it´s not just looks.

    All in all this was a supernice thread to read, and also lots of great input from Rich and others. Inspiring.
    Wish you many happy working hours with the Studer.

    Cheers

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    Quote Originally Posted by Lumberjack View Post
    Wish you many happy working hours with the Studer.
    Thanks. Unfortunately I'm still spending time making stuff so that I can use the machine. But this time is getting closer.

    To get out the taper, and then to put in desired tapers, one needs a stable mount for a precise measuring device. So I spent some time making this mount for a Tesa dial indicator which was already in my collection. The base is cast iron cut off my practice piece from earlier in this thread. I have the factory mounting box but it requires an unusually small Compac dial indicator which is no longer sold or available.



    Note that the location (left/right) is critical and must be right to within about 0.05mm = 0.002" or you won't be able to get taper angles exactly right with gage blocks.



    I still need to replace the indicator tip with one that has a smaller radius of curvature (almost a point would be ideal).



    I'll make a transparent protective cover out of polycarbonate (lexan).

    On the bottom right you can see the "spyglass" that I added for monitoring the oil going to the ways. It's reassuring to be able to see that at a glance.
    Last edited by ballen; 02-16-2018 at 05:45 AM.

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  26. #119
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    The polycarbonate (lexan, makrolon) cover is done, back to learning how to run the grinder.


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    Bruce and Richard!

    Guys: This has been a very impressive and didactic discussion to follow! I do recognize only too well the development from "it cannot be that important" to "this is obviously the way to do it". Thanks a lot, not he least to you, Richard, spreading your knowledge to all who cares to listen, just for the thrill of creating a legacy!

    Ole

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