Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work.

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Alan Rothenbush
 
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Default Can something be TOO flat ?


Can two sliding surfaces be too flat to slide nicely ?

Here's the story. I bought a little ( 4x7 ) Sanford Surface Grinder
off eBay. Got it home, did some checking and found the ways pretty
worn in the middle of the travel. ( The ways are a V way and flat way )

So I spent all of yesterday with my good friend Marcus, a tool and
die maker of what is, to me, extraordinary skill and knowledge.

I learned a WHOLE bunch about surface grinding and even more about the
use of prussian blue.

After form grinding the V way and flat of the saddle, we mounted the little
Sanford table on the great big table of Marcus' grinder. ( His mag chuck was
almost the size of the Sanford's table ! )

The saddle was ground first, as it had some ground surfaces obviously used
as refereneces in the initial construction.

We form ground the V of the table and then proceeded to grind the last flat.

The problem here is that the relative heights of the V and the flat must
absolutely correct or the flats will not sit parallel to each other, but
will instead sit an at angle. The contact will then be along two lines, as
opposed to three planes ( one side of the V, the other side of the V and
the flat ).

The first cleanup pass got us, by measurement and calculation, about .002"
high.

We spent the next 2 hours getting rid of that two thou, about .000,2" at a
time. That is, remove a tenth or so, blue, look, measure, grind another
tenth and a bit, blue look measure, and so on. We finally got to a point
where the blueing matched the measurements matched the initial calculations.

At this point we removed the table, mounted it on the saddle and gave it a
slide. BEAUTIFUL. Absolutely fabulous.

I'd spent a week wondering if I had bought two hundred pounds of scrap cast
iron and left wondering how I could be so lucky.

Then I got home.

First thing I did was to oil the freshly ground surfaces, something we hadn't
done. I then slid the table along, expecting to almost glide off the end, only
to find it .. sticking .. kind of a hydraulic sort of stick. I kept sliding it
back and forth, getting stickier and stickier until it stuck solidly.

It took a LOT of force to break it free .. in fact, they were stuck so firmly
together that that lifting the table also lifted the saddle.

Once apart, I examined things and found nothing but clean, nicely oiled
surfaces. The oil I used was nearly clear and it was still nearly clear,
allowing a good look at things. Nothing. Finger test showed .. nothing.

Tried again and found the same thing. Cleaned all the (light) oil off and
tried some heavier oil. Same thing. Cleaned the heavier oil off and tried
the lightest oil I could find. Same effect.

It's like the back and forth slide acts like a pump, and a hydraulic "lock"
is generated.

All of this is absolutely foreign to me. Two flat things with oil between
them has always slid smoothly, but I've never had any two things THIS flat.

Can something be TOO flat to slide properly ?


Thanks for any thoughts.


Alan

--
Alan Rothenbush | The Spartans do not ask the number of the
Academic Computing Services | enemy, only where they are.
Simon Fraser University |
Burnaby, B.C., Canada | Agix of Sparta
  #2   Report Post  
Beelzebub
 
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Default Can something be TOO flat ?

Alan Rothenbush wrote in message
...

Can two sliding surfaces be too flat to slide nicely ?


Yes


  #3   Report Post  
Ed Huntress
 
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Default Can something be TOO flat ?

"Alan Rothenbush" wrote in message
...

Can two sliding surfaces be too flat to slide nicely ?


Yes, although it's pretty rare. Ground surfaces on machine tool ways are
best used with pressure oil systems. When you don't have oil pressure, it is
possible, with an exceptional grinding job, to get high friction.

The cure used in most machine tools is to "frost" the way surfaces, which is
a sort of after-the fact scraping job, usually done with a power scraper to
produce a decorative surface effect. You want it to be very shallow and you
aren't scraping to a standard here. You're just trying to reduce the bearing
area and leave some low areas (by millionths, not by tenths) to hold oil and
to reduce the contact area.

A good scraped surface has something like 60% bearing. Some machines, like
older Moore jig borers and jig grinders, allegedly ran around 80% bearing.
Anything more could be trouble.

Now you need a hands-on expert to explain what to do. All I'm doing is
passing on what experts have told me over 30 years of asking and
interviewing them -- including people at Moore.

Ed Huntress


  #4   Report Post  
Alan Moore
 
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Default Can something be TOO flat ?

On Sun, 14 Dec 2003 19:40:17 +0000 (UTC), Alan Rothenbush
wrote:


Can two sliding surfaces be too flat to slide nicely ?

snip

The phenomenon you describe is well known to amatuer telescope makers
who discover a marked increase in difficulty when glass surfaces being
ground get close to actual optical levels of flatness. Mirrors have
been destroyed by the measures taken to separate them from grinding
tools, and lapping tools are normally provided with grooves to prevent
binding of this sort.

Suggestion: use a lower viscosity oil. It will flow more freely into
the space between the facing surfaces. If things are really stuck as
they are, use a little heat as well as adding lighter oil...

Al Moore
  #5   Report Post  
 
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Default Can something be TOO flat ?

On Sun, 14 Dec 2003 19:40:17 +0000 (UTC), Alan Rothenbush
wrote:


Can two sliding surfaces be too flat to slide nicely ?

Here's the story. I bought a little ( 4x7 ) Sanford Surface Grinder
off eBay. Got it home, did some checking and found the ways pretty
worn in the middle of the travel. ( The ways are a V way and flat way )

So I spent all of yesterday with my good friend Marcus, a tool and
die maker of what is, to me, extraordinary skill and knowledge.

I learned a WHOLE bunch about surface grinding and even more about the
use of prussian blue.

After form grinding the V way and flat of the saddle, we mounted the little
Sanford table on the great big table of Marcus' grinder. ( His mag chuck was
almost the size of the Sanford's table ! )

The saddle was ground first, as it had some ground surfaces obviously used
as refereneces in the initial construction.

We form ground the V of the table and then proceeded to grind the last flat.

The problem here is that the relative heights of the V and the flat must
absolutely correct or the flats will not sit parallel to each other, but
will instead sit an at angle. The contact will then be along two lines, as
opposed to three planes ( one side of the V, the other side of the V and
the flat ).

The first cleanup pass got us, by measurement and calculation, about .002"
high.

We spent the next 2 hours getting rid of that two thou, about .000,2" at a
time. That is, remove a tenth or so, blue, look, measure, grind another
tenth and a bit, blue look measure, and so on. We finally got to a point
where the blueing matched the measurements matched the initial calculations.

At this point we removed the table, mounted it on the saddle and gave it a
slide. BEAUTIFUL. Absolutely fabulous.

I'd spent a week wondering if I had bought two hundred pounds of scrap cast
iron and left wondering how I could be so lucky.

Then I got home.

First thing I did was to oil the freshly ground surfaces, something we hadn't
done. I then slid the table along, expecting to almost glide off the end, only
to find it .. sticking .. kind of a hydraulic sort of stick. I kept sliding it
back and forth, getting stickier and stickier until it stuck solidly.

It took a LOT of force to break it free .. in fact, they were stuck so firmly
together that that lifting the table also lifted the saddle.

Once apart, I examined things and found nothing but clean, nicely oiled
surfaces. The oil I used was nearly clear and it was still nearly clear,
allowing a good look at things. Nothing. Finger test showed .. nothing.

Tried again and found the same thing. Cleaned all the (light) oil off and
tried some heavier oil. Same thing. Cleaned the heavier oil off and tried
the lightest oil I could find. Same effect.

It's like the back and forth slide acts like a pump, and a hydraulic "lock"
is generated.

All of this is absolutely foreign to me. Two flat things with oil between
them has always slid smoothly, but I've never had any two things THIS flat.

Can something be TOO flat to slide properly ?



Yes

See http://www.moglice.com/newsite/frame...ightframe.html

Jim


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Dave Baker
 
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Default Can something be TOO flat ?

Subject: Can something be TOO flat ?
From: Alan Rothenbush
Date: 14/12/03 19:40 GMT Standard Time
Message-id:


Can two sliding surfaces be too flat to slide nicely ?

Here's the story. I bought a little ( 4x7 ) Sanford Surface Grinder
off eBay. Got it home, did some checking and found the ways pretty
worn in the middle of the travel. ( The ways are a V way and flat way )

So I spent all of yesterday with my good friend Marcus, a tool and
die maker of what is, to me, extraordinary skill and knowledge.

I learned a WHOLE bunch about surface grinding and even more about the
use of prussian blue.

After form grinding the V way and flat of the saddle, we mounted the little
Sanford table on the great big table of Marcus' grinder. ( His mag chuck was
almost the size of the Sanford's table ! )

The saddle was ground first, as it had some ground surfaces obviously used
as refereneces in the initial construction.

We form ground the V of the table and then proceeded to grind the last flat.


The problem here is that the relative heights of the V and the flat must
absolutely correct or the flats will not sit parallel to each other, but
will instead sit an at angle. The contact will then be along two lines, as
opposed to three planes ( one side of the V, the other side of the V and
the flat ).

The first cleanup pass got us, by measurement and calculation, about .002"
high.

We spent the next 2 hours getting rid of that two thou, about .000,2" at a
time. That is, remove a tenth or so, blue, look, measure, grind another
tenth and a bit, blue look measure, and so on. We finally got to a point
where the blueing matched the measurements matched the initial calculations.

At this point we removed the table, mounted it on the saddle and gave it a
slide. BEAUTIFUL. Absolutely fabulous.

I'd spent a week wondering if I had bought two hundred pounds of scrap cast
iron and left wondering how I could be so lucky.

Then I got home.

First thing I did was to oil the freshly ground surfaces, something we hadn't

done. I then slid the table along, expecting to almost glide off the end,
only
to find it .. sticking .. kind of a hydraulic sort of stick. I kept sliding
it
back and forth, getting stickier and stickier until it stuck solidly.

It took a LOT of force to break it free .. in fact, they were stuck so firmly
together that that lifting the table also lifted the saddle.

Once apart, I examined things and found nothing but clean, nicely oiled
surfaces. The oil I used was nearly clear and it was still nearly clear,
allowing a good look at things. Nothing. Finger test showed .. nothing.

Tried again and found the same thing. Cleaned all the (light) oil off and
tried some heavier oil. Same thing. Cleaned the heavier oil off and tried
the lightest oil I could find. Same effect.

It's like the back and forth slide acts like a pump, and a hydraulic "lock"
is generated.

All of this is absolutely foreign to me. Two flat things with oil between
them has always slid smoothly, but I've never had any two things THIS flat.

Can something be TOO flat to slide properly ?


Yes. You've generated a huge contact area and the surfaces are now binding to
each other with the stiction of the oil which is sufficient to make the contact
airtight. You are generating something similar to what happens when you wring
two slip guages together. You need some surface irregularities to reduce the
contact area and let air get into the gaps. I think if you try the ways bone
dry they will perform much better. You might also try paraffin (kerosene)
instead of oil but I suspect any liquid will now make them stick until you
rough the surfaces up a bit.


Dave Baker - Puma Race Engines (
www.pumaracing.co.uk)
I'm not at all sure why women like men. We're argumentative, childish,
unsociable and extremely unappealing naked. I'm quite grateful they do though.
  #8   Report Post  
Ed Huntress
 
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Default Can something be TOO flat ?

"Fdmorrison" wrote in message
...
"Ed Huntress"

Yes, although it's pretty rare. Ground surfaces on machine tool ways are
best used with pressure oil systems. When you don't have oil pressure, it

is
possible, with an exceptional grinding job, to get high friction.

The cure used in most machine tools is to "frost" the way surfaces, which

is
a sort of after-the fact scraping job, usually done with a power scraper

to
produce a decorative surface effect. You want it to be very shallow and

you
aren't scraping to a standard here. You're just trying to reduce the

bearing
area and leave some low areas (by millionths, not by tenths) to hold oil

and
to reduce the contact area.


Final scraping called "frosting," or "flaking" is used for hand scraping

of
ways for decoration (allegedly to hold oil), but would you want to use it

after
final grinding (other than for decoration)?


Yeah, that's how it was used a half-century ago. Real top-quality
hand-scraping jobs, like on Moores, weren't finished with frosting. BTW,
"flaking" was a term usually applied to hand-scraping of little points;
"frosting" usually was reserved for the more decorate, half-moon or other
patterns.

Even back in the '40s, it usually was done by power after grinding, on
mass-produced lathes and mills.

Whether it was purely decorative or not depended on the manufacturer and how
they did it.


If the surfaces here related "stuck" together dry (as Jo blocks) on

wringing,
that would be one thing, but that's not the case so far related.
FM


I won't try to analyze it, but my understanding is that it's simple adhesion
from too much area with too-thin a layer of oil between the surfaces. The
tribologists here can argue that one out. g

Ed Huntress


  #9   Report Post  
jim rozen
 
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Default Can something be TOO flat ?

In article , Ed Huntress
says...

Yeah, that's how it was used a half-century ago. Real top-quality
hand-scraping jobs, like on Moores, weren't finished with frosting.


The jig borers had hardened steel prismatic ways, ground to size.
They were seated in hand scraped female v-ways, scraped for
alignment. The ground surfaces were then lapped for alignment.
Because they were hard steel, they could not be scraped or
frosted.

The female v-ways that rode on the hardened prismatic ways
were hand scraped though. So even in this case the degree
of bearing was controlled, to be below a certain percentage.

I'm not sure if moore's book mentiones what that number
was that they considered optimal.

As a side note, a lot of the fancy photos of old machine
tools, which were covered with decorative engine turning or
frosting on the non-function surfaces were done as one-offs
for the catalog photos, I bet. Or, maybe there was a bit
of old-timey photoshopping going on! The cataract lathe
I have came with a nearly unused cross slide:

http://www.geocities.com/noramm10566/59slide3.jpg

Even though the ways and lead screws were pristine, and
showed zero wear, it still did not look much like what
hardinge said it should:

http://www.lathes.co.uk/cataract/img86.gif

A bit of a difference, eh?

Jim

Jim

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Anthony
 
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Default Can something be TOO flat ?

(Fdmorrison) wrote in
:

"Ed Huntress"


Yes, although it's pretty rare. Ground surfaces on machine tool ways
are best used with pressure oil systems. When you don't have oil
pressure, it is possible, with an exceptional grinding job, to get
high friction.

The cure used in most machine tools is to "frost" the way surfaces,
which is a sort of after-the fact scraping job, usually done with a
power scraper to produce a decorative surface effect. You want it to
be very shallow and you aren't scraping to a standard here. You're
just trying to reduce the bearing area and leave some low areas (by
millionths, not by tenths) to hold oil and to reduce the contact area.


Final scraping called "frosting," or "flaking" is used for hand
scraping of ways for decoration (allegedly to hold oil), but would you
want to use it after final grinding (other than for decoration)?

If the surfaces here related "stuck" together dry (as Jo blocks) on
wringing, that would be one thing, but that's not the case so far
related. FM



too flat of a surface can create a hydraulic lock between parts. The ways
need to be scraped. The oil gets squeezed out of two really flat surfaces
and the parts adhere just like wringing jo blocks. Which is why it
occured after moving the slide back and forth a few times. Scraping keeps
pockets of oil between the metal surfaces.


--
Anthony

You can't 'idiot proof' anything....every time you try, they just make
better idiots.

Remove sp to reply via email


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Ed Huntress
 
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Default Can something be TOO flat ?

"jim rozen" wrote in message
...
In article , Ed

Huntress
says...

Yeah, that's how it was used a half-century ago. Real top-quality
hand-scraping jobs, like on Moores, weren't finished with frosting.


The jig borers had hardened steel prismatic ways, ground to size.
They were seated in hand scraped female v-ways, scraped for
alignment. The ground surfaces were then lapped for alignment.
Because they were hard steel, they could not be scraped or
frosted.


Oh, right, I was thinking of their gages and so on. They were pointed to a
high bearing percentage -- 'looked like speckling on a trout.

Ed Huntress


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BBFMETALWORKING
 
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Default Can something be TOO flat ?

Yes, super flat surfaces don't have any "pockets" to retain oil
between them. In the same way as you demonstrated, good gauge blocks
stick together when you slide them on to each other. Scraping to
leave that "frosting" on flat bearing surfaces is more than
decorative. It provides pockets for oil retention and therefore low
friction sliding.


Alan Rothenbush wrote in message ...
Can two sliding surfaces be too flat to slide nicely ?


Alan

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Alan Rothenbush
 
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Default Can something be TOO flat ?

In article , Dave Baker wrote:

I think if you try the ways bone
dry they will perform much better.


Yes, they slide quite smoothly when perfectly dry.


Alan

--
Alan Rothenbush | The Spartans do not ask the number of the
Academic Computing Services | enemy, only where they are.
Simon Fraser University |
Burnaby, B.C., Canada | Agix of Sparta
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jim rozen
 
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Default Can something be TOO flat ?

In article , Ed Huntress
says...

Oh, right, I was thinking of their gages and so on. They were pointed to a
high bearing percentage -- 'looked like speckling on a trout.


One of my most fond rememberances at work will be a swiss
EDM operator (since retired) who also was in charge of
a moore jig borer.

One morning he arrived to find that the painters had been
in over the weekend and had painted the jig borer. Including
the ways!! You should have heard the cursing and hollering.

He had actually met Moore at one point in CT.

Jim

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  #16   Report Post  
jim rozen
 
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Default Can something be TOO flat ?

In article , Fdmorrison says...

"[S]ome machine builders still cling to the practice of handscraping the
ways--an admission that the machine work is not quite so accurate as it should
be. In these days of precision machine tools, it is indeed surprising to find
tool engineers who believe that a man with a scraper can produce a surface more
nearly flat than can be planed with a single-point tool on a modern planer [let
alone, grinding machine]."


And here Moore's smarts really show - his idea is not
to create a bearing surface with the scraper, but rather
to prepare and align a seat for the real bearing (the
hard steel prism, ground for dimension and surface
finish) and then bolted into the way whos (whoms? g)
alignment has been prepared by hand scraping. Sort
of the best of both.

In any event, moore felt that machine tool accuracy, and
that includes the planer mentioned above, depended ultimately
on hand scraped gages that were developed fundamentally from
master reference flats - hand scraped master reference flats.

This was not really a new concept, moore simply carried it
to extremes. But even in the mid 40s I suspect that it was
cheaper to hire an experience scraper mechanic to finsh, say,
lathe beds. Because the large machines to do them cost a
lot, and the men could be paid a fairly low wage in spite
of their skill.

Jim

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Ed Huntress
 
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Default Can something be TOO flat ?

"jim rozen" wrote in message
...
In article , Ed

Huntress
says...

Oh, right, I was thinking of their gages and so on. They were pointed to

a
high bearing percentage -- 'looked like speckling on a trout.


One of my most fond rememberances at work will be a swiss
EDM operator (since retired) who also was in charge of
a moore jig borer.

One morning he arrived to find that the painters had been
in over the weekend and had painted the jig borer. Including
the ways!! You should have heard the cursing and hollering.

He had actually met Moore at one point in CT.


I assume you mean the original, Richard (Dick). I used to have lunch with
him once a year. It was something I really looked forward to.

That was at the American Machinist Annual Award Winner luncheon. I actually
got to sit next to Dick Moore and two places from Isaac Asimov at one of
those. I tried to remember every word they said. Maybe I did...I don't
remember. g

Ed Huntress


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Jon Elson
 
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Default Can something be TOO flat ?



Alan Rothenbush wrote:

It's like the back and forth slide acts like a pump, and a hydraulic "lock"
is generated.

All of this is absolutely foreign to me. Two flat things with oil between
them has always slid smoothly, but I've never had any two things THIS flat.

Can something be TOO flat to slide properly ?


Lots of affirmative comments, but not a lot of help on what
to do. Are you using way oil? If not, get some. It is designed
to not squish out of large, low PSI slideways. If this doesn't help,
they you are most likely going to have to frost it a bit to reduce
the gage-block effect. Having difficulty separating the surfaces is
not a problem, you don't WANT the surfaces to separate. But, you
do want to retain a thin oil film on the ways. If it has an oil
feed system, get that working so it applies a slow feed of oil to
the ways. That will prevent the film thinning down to nearly zero.


Marcus must have a REALLY fine surface grinder to make surfaces this
true!

Jon

  #20   Report Post  
jran
 
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Default Can something be TOO flat ?

some machine ways have a "S" shaped groove in them to help retain the oil. I
don't know if you could create a groove simply enough. the groove seems to
help the way float on each other like a hydrodynamic spindle (I think that
the term). But some how some small groove parallel to the ways would work, I
would think if you could scrape them yourself but maybe there's a retired
person in your area who could do this for some beer and time to chat about
the old days.

"Alan Rothenbush" wrote in message
...

Can two sliding surfaces be too flat to slide nicely ?

Here's the story. I bought a little ( 4x7 ) Sanford Surface Grinder
off eBay. Got it home, did some checking and found the ways pretty
worn in the middle of the travel. ( The ways are a V way and flat way )

So I spent all of yesterday with my good friend Marcus, a tool and
die maker of what is, to me, extraordinary skill and knowledge.

I learned a WHOLE bunch about surface grinding and even more about the
use of prussian blue.

After form grinding the V way and flat of the saddle, we mounted the

little
Sanford table on the great big table of Marcus' grinder. ( His mag chuck

was
almost the size of the Sanford's table ! )

The saddle was ground first, as it had some ground surfaces obviously used
as refereneces in the initial construction.

We form ground the V of the table and then proceeded to grind the last

flat.

The problem here is that the relative heights of the V and the flat must
absolutely correct or the flats will not sit parallel to each other, but
will instead sit an at angle. The contact will then be along two lines,

as
opposed to three planes ( one side of the V, the other side of the V and
the flat ).

The first cleanup pass got us, by measurement and calculation, about .002"
high.

We spent the next 2 hours getting rid of that two thou, about .000,2" at a
time. That is, remove a tenth or so, blue, look, measure, grind another
tenth and a bit, blue look measure, and so on. We finally got to a point
where the blueing matched the measurements matched the initial

calculations.

At this point we removed the table, mounted it on the saddle and gave it a
slide. BEAUTIFUL. Absolutely fabulous.

I'd spent a week wondering if I had bought two hundred pounds of scrap

cast
iron and left wondering how I could be so lucky.

Then I got home.

First thing I did was to oil the freshly ground surfaces, something we

hadn't
done. I then slid the table along, expecting to almost glide off the end,

only
to find it .. sticking .. kind of a hydraulic sort of stick. I kept

sliding it
back and forth, getting stickier and stickier until it stuck solidly.

It took a LOT of force to break it free .. in fact, they were stuck so

firmly
together that that lifting the table also lifted the saddle.

Once apart, I examined things and found nothing but clean, nicely oiled
surfaces. The oil I used was nearly clear and it was still nearly clear,
allowing a good look at things. Nothing. Finger test showed .. nothing.

Tried again and found the same thing. Cleaned all the (light) oil off and
tried some heavier oil. Same thing. Cleaned the heavier oil off and

tried
the lightest oil I could find. Same effect.

It's like the back and forth slide acts like a pump, and a hydraulic

"lock"
is generated.

All of this is absolutely foreign to me. Two flat things with oil between
them has always slid smoothly, but I've never had any two things THIS

flat.

Can something be TOO flat to slide properly ?


Thanks for any thoughts.


Alan

--
Alan Rothenbush | The Spartans do not ask the number of the
Academic Computing Services | enemy, only where they are.
Simon Fraser University |
Burnaby, B.C., Canada | Agix of Sparta





  #21   Report Post  
Gunner
 
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Default Can something be TOO flat ?

I know this sounds like Blasphemy!!!!!!!!!!

But how about making some figure 8s with a red scotchbrite pad over
the entire surface? Just a light once over?

Gunner

" ..The world has gone crazy. Guess I'm showing my age...
I think it dates from when we started looking at virtues
as funny. It's embarrassing to speak of honor, integrity,
bravery, patriotism, 'doing the right thing', charity,
fairness. You have Seinfeld making cowardice an acceptable
choice; our politicians changing positions of honor with
every poll; we laugh at servicemen and patriotic fervor; we
accept corruption in our police and bias in our judges; we
kill our children, and wonder why they have no respect for
Life. We deny children their childhood and innocence- and
then we denigrate being a Man, as opposed to a 'person'. We
*assume* that anyone with a weapon will use it against his
fellowman- if only he has the chance. Nah; in our agitation
to keep the State out of the church business, we've
destroyed our value system and replaced it with *nothing*.
Turns my stomach- " Chas , rec.knives
  #22   Report Post  
Alan Rothenbush
 
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Default Can something be TOO flat ?

In article , Gunner wrote:
I know this sounds like Blasphemy!!!!!!!!!!

But how about making some figure 8s with a red scotchbrite pad over
the entire surface? Just a light once over?


I considered this myself, but I think it's time I learned how to use
a scraper for something other than making a bad fit, worse.

Alan

--
Alan Rothenbush | The Spartans do not ask the number of the
Academic Computing Services | enemy, only where they are.
Simon Fraser University |
Burnaby, B.C., Canada | Agix of Sparta
  #23   Report Post  
Alan Rothenbush
 
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Default Can something be TOO flat ?

In article , Jon Elson wrote:

Lots of affirmative comments, but not a lot of help on what
to do. Are you using way oil? If not, get some. It is designed
to not squish out of large, low PSI slideways. If this doesn't help,
they you are most likely going to have to frost it a bit to reduce
the gage-block effect. Having difficulty separating the surfaces is
not a problem, you don't WANT the surfaces to separate. But, you
do want to retain a thin oil film on the ways. If it has an oil
feed system, get that working so it applies a slow feed of oil to
the ways. That will prevent the film thinning down to nearly zero.


The oil feed is a couple of GITS cups, and the "owner's manual" says
to refill them once a week in normal use.

I'm not sure that's a solution .. sounds like scraper time.


Marcus must have a REALLY fine surface grinder to make surfaces this
true!


He moaned about the quality of it all day, but based upon what I see in
front of me, when he throws it out, I'm going to pick it up !

I think I got a first hand lesson on the difference between a machinist
and a tool and die maker. I always kinda thought a T&D guy was a machinist
who made tools. I'm starting to think the comparison is more along the
lines of a woodworker and a machinist; just a whole order of magnitude
higher precision.

Marcus was perfectly happy spending his whole day knocking a tenth off,
blueing and measuring, knocking a tenth off, all day, until it was "right".
I thought it was just fine about an hour before we finally did finish, but
Marcus wasn't quitting until it was "done".

It was a very informative day.

Alan

--
Alan Rothenbush | The Spartans do not ask the number of the
Academic Computing Services | enemy, only where they are.
Simon Fraser University |
Burnaby, B.C., Canada | Agix of Sparta
  #24   Report Post  
Ed Huntress
 
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Default Can something be TOO flat ?

"Gunner" wrote in message
...
I know this sounds like Blasphemy!!!!!!!!!!

But how about making some figure 8s with a red scotchbrite pad over
the entire surface? Just a light once over?


Go wash your mouth out with soap. Now go to the blackboard and write, 1,000
times,...

Something simple ought to work, and maybe Scotchbrite isn't a terrible idea,
but there must be something better.

I was wondering about acid, but I don't want to be liable for contributing
to the wrecking of somebody else's machine.

Ed Huntress


  #25   Report Post  
jim rozen
 
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Default Can something be TOO flat ?

In article , Ed Huntress
says...

He had actually met Moore at one point in CT.


I assume you mean the original, Richard (Dick). I used to have lunch with
him once a year. It was something I really looked forward to.


Yes, that's right. JC (the wire edm guy) met him one
time. I think that was when moore was still in bridgeport,
he said that the neighborhood around the plant was very
bad.

Jim

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  #26   Report Post  
jim rozen
 
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Default Can something be TOO flat ?

In article , Ed Huntress
says...

Something simple ought to work, and maybe Scotchbrite isn't a terrible idea,
but there must be something better.


Scotchbright contains silica and this might possibly
embed in the ways and continue to cause wear. I
would avoid it.

Jim

==================================================
please reply to:
JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com
==================================================

  #27   Report Post  
Bob May
 
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Default Can something be TOO flat ?

Actually, you are in the range where the lubricant can't flow into the hills
and valleys that are still lef freelyt. In other words, you aren't flat
enough!
The best way is to put a bunch of grooves in one of the surfaces to allow
the vacuum to easily allow the flow of the lubricant into those areas that
open up.
This is a problem that often happens with grinding an optical glass surface
and we work it out by grinding the surfaces into better contact with the
grit that we are using. Ultimately tho, if the surfaces are too smooth and
in good contact with each other, you can get welding of the two pieces
together as has been found out about in space where there is no air to hold
the pieces apart.
If you want to, put some more prussian blue on the ways and do a little more
scraping to get things even flatter which will minize the hills that are
left, making the generation of a vacuum less and then scribe some flow lines
into one surface to allow for the lube to flow better.

--
Bob May
Losing weight is easy! If you ever want to lose weight, eat and drink less.
Works evevery time it is tried!


  #28   Report Post  
Stormin Mormonn
 
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Default Can something be TOO flat ?

Try silicone or graphite?

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Jesus: The Reason for the Season
www.lds.org
www.mormons.com


"Alan Rothenbush" wrote in message
...

Can two sliding surfaces be too flat to slide nicely ?

Here's the story. I bought a little ( 4x7 ) Sanford Surface Grinder
off eBay. Got it home, did some checking and found the ways pretty
worn in the middle of the travel. ( The ways are a V way and flat way )

So I spent all of yesterday with my good friend Marcus, a tool and
die maker of what is, to me, extraordinary skill and knowledge.

I learned a WHOLE bunch about surface grinding and even more about the
use of prussian blue.

After form grinding the V way and flat of the saddle, we mounted the little
Sanford table on the great big table of Marcus' grinder. ( His mag chuck was
almost the size of the Sanford's table ! )

The saddle was ground first, as it had some ground surfaces obviously used
as refereneces in the initial construction.

We form ground the V of the table and then proceeded to grind the last flat.

The problem here is that the relative heights of the V and the flat must
absolutely correct or the flats will not sit parallel to each other, but
will instead sit an at angle. The contact will then be along two lines, as
opposed to three planes ( one side of the V, the other side of the V and
the flat ).

The first cleanup pass got us, by measurement and calculation, about .002"
high.

We spent the next 2 hours getting rid of that two thou, about .000,2" at a
time. That is, remove a tenth or so, blue, look, measure, grind another
tenth and a bit, blue look measure, and so on. We finally got to a point
where the blueing matched the measurements matched the initial calculations.

At this point we removed the table, mounted it on the saddle and gave it a
slide. BEAUTIFUL. Absolutely fabulous.

I'd spent a week wondering if I had bought two hundred pounds of scrap cast
iron and left wondering how I could be so lucky.

Then I got home.

First thing I did was to oil the freshly ground surfaces, something we
hadn't
done. I then slid the table along, expecting to almost glide off the end,
only
to find it .. sticking .. kind of a hydraulic sort of stick. I kept sliding
it
back and forth, getting stickier and stickier until it stuck solidly.

It took a LOT of force to break it free .. in fact, they were stuck so
firmly
together that that lifting the table also lifted the saddle.

Once apart, I examined things and found nothing but clean, nicely oiled
surfaces. The oil I used was nearly clear and it was still nearly clear,
allowing a good look at things. Nothing. Finger test showed .. nothing.

Tried again and found the same thing. Cleaned all the (light) oil off and
tried some heavier oil. Same thing. Cleaned the heavier oil off and tried
the lightest oil I could find. Same effect.

It's like the back and forth slide acts like a pump, and a hydraulic "lock"
is generated.

All of this is absolutely foreign to me. Two flat things with oil between
them has always slid smoothly, but I've never had any two things THIS flat.

Can something be TOO flat to slide properly ?


Thanks for any thoughts.


Alan

--
Alan Rothenbush | The Spartans do not ask the number of the
Academic Computing Services | enemy, only where they are.
Simon Fraser University |
Burnaby, B.C., Canada | Agix of Sparta


  #29   Report Post  
Ian Stirling
 
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Default Can something be TOO flat ?

Stormin Mormonn wrote:
Try silicone or graphite?


Or give it a going over with some #60 sandpaper.
  #30   Report Post  
Fred Klingener
 
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Default Can something be TOO flat ?

"Alan Rothenbush" wrote in message
...

Can two sliding surfaces be too flat to slide nicely ?


Technically, yeah. Think about Jo blocks. But I don't think you can get
there with a grinder. :-)

I wouldn't mess with it until I was sure both parts had had a chance to warm
up and get comfortable in their new surroundings after their ride home.

After that, I'd see whether I needed to deGauss either of the parts. You
briefly mentioned mag bases, but didn't describe any of it for me to to do
anything but offer a wild (and possibly humiliating) hunch.

After that, it sounds like it's time to wipe the ways dry and a try a little
Dykem. See whether it's localized somewhere.

hth,
Fred Klingener


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