I'm looking at machines for a home shop where I work on a wide variety
of projects. I can't decide which way to go:

1. Get a new Chinese mill (such as grizzly, harbor freight, etc...)
2. Get an old high-end mill (Bridgeport, etc...)

Assume the machines have very similar specs (in fact, the Chinese
machine may be a copy of the Bridgeport!). Assume also, that I
wouldn't be able to afford the better used machines out there.
Compare, for example:

http://www.grizzly.com/products/item...emNumber=G6760
http://cgi.ebay.com/ws/eBayISAPI.dll...m=3823642 872

These two machines both cost about $2,500.

In both cases, I would expect to spend a fair amount of work to get
the machine into good shape. The Chinese machine will come with a
variety of small problems and generally poor fit & finish -- it will
need a comprehensive overhaul out of the box. A low-price used
Bridgeport will probably also need a fair amount of work, maybe some
new parts, etc... and may be somewhat the worse for wear.

Are old mills on the market for $2,500 likely to be worn out? How
much is it going to cost to get them into good running shape? Once
it's tuned up, will the Chinese mill perform as well as the older
Bridgeport?

Thanks!
-Bill

On 3 Jul 2004 17:18:00 -0700, (Bill Ross) wrote:
I'm looking at machines for a home shop where I work on a wide variety
of projects. I can't decide which way to go:

1. Get a new Chinese mill (such as grizzly, harbor freight, etc...)
2. Get an old high-end mill (Bridgeport, etc...)

Assume the machines have very similar specs (in fact, the Chinese
machine may be a copy of the Bridgeport!). Assume also, that I
wouldn't be able to afford the better used machines out there.
Compare, for example:

http://www.grizzly.com/products/item...emNumber=G6760
http://cgi.ebay.com/ws/eBayISAPI.dll...m=3823642 872

These two machines both cost about $2,500.

The Griz has a power feed, the Bridgie doesn't.
Of course you can add a power feed to the Bridgie,
but that's extra $$$.

The Bridgie has a vari-speed head, the Griz doesn't.
Old vari-speeds can be trouble, and expensive to
repair, OTOH being limited to 5 speeds tends to suck,
especially since the Griz doesn't have back gears.
(That'd make boring and face milling problematic.)

The Bridgie requires 3 ph power, the Griz runs on household
AC. This has both pluses and minuses. You won't need a
rotary converter or VFD to run the Griz. OTOH, you can't use
a VFD to give the Griz vari-speed. You will need to budget for
a rotary converter or VFD to run the Bridgie in a home shop.
That need not be very expensive, but you have to have it.

The Bridgie has obvious rust, hopefully the Griz doesn't.
(Harold would have a fit, but the rust doesn't look too
bad in the pictures. It'd probably clean up ok.)

Between those two particular machines, I'd probably gamble
on the Bridgeport. However, you're really comparing apples
and oranges. The Griz you selected is a lightweight. A closer
Griz match to the Bridgie would be

http://www.grizzly.com/products/item...emNumber=G9903

Now you're closer to comparing apples with apples. Mass is
critical in a mill, more is better. No way a light mill can equal
a heavier one in terms of rigidity. Rigidity is the primary thing,
other than wear, that controls the ultimate precision and quality
of cut a mill is capable of producing. (Yes, now we're talking
about a $4,000 machine, but a Bridgeport was an $18,000
machine when it was new.)

In both cases, I would expect to spend a fair amount of work to get
the machine into good shape. The Chinese machine will come with a
variety of small problems and generally poor fit & finish -- it will
need a comprehensive overhaul out of the box. A low-price used
Bridgeport will probably also need a fair amount of work, maybe some
new parts, etc... and may be somewhat the worse for wear.

I wouldn't say the Chinese machine would require a comprehensive
overhaul. You will need to clean off the shipping grease, check for
casting sand, change the lubricant, maybe deburr a few edges, do
normal adjustments and setup, etc, but you shouldn't need to fabricate,
modify, or replace any parts. I have an ENCO mill similar to the larger
of the 2 Grizzly mills listed above. It took about 4 hours to get it ready
to work.

You know you're going to have to derust the Bridgie, maybe work
on the vari-speed ($$$), and if there is significant wear in critical
areas, returning it to like new precision is almost certainly going
to cost more than it is worth. (Not saying that's the case with the
particular machine you listed, but it could be.)

Are old mills on the market for $2,500 likely to be worn out? How
much is it going to cost to get them into good running shape? Once
it's tuned up, will the Chinese mill perform as well as the older
Bridgeport?

The light Chinese machine you chose is never going to match the
performance of a Bridgeport in good condition. OTOH the Griz model
I indicated probably would equal or surpass a used Bridgeport with
very minimal setup.

It is possible to find a Bridgie which has only had light use, and has
been well maintained. That would be a good machine to have. But it
is also possible to find one that's got serious and expensive problems.
You can't generalize too much about used equipment. Everything
depends on the exact details of the condition of the particular machine.

To answer your question, yes it is possible to get a used Bridgeport
in good condition for $2500 (sometimes less if you bypass dealers and
handle it as a private sale). The real question is, how can you be sure
the one you choose actually is in good condition? And what will it cost
to repair it if it isn't?

If you aren't intimately familiar with the machines, it'll probably pay to
hire a good independent Bridgeport tech to inspect any used machine
you might want to buy. He'll be able to spot problems that you'd probably
completely miss, and tell you whether it is worth the cost of repair.

Note that while Machinery Values offers a 30 day return privilege,
you'd still be stuck with the freight charges both ways, and these
machines are heavy, so that could be a fair sum of money. It'd
be better to get the machine checked up front before it is bought
and shipped. At least they say it can be inspected under power.
That's a good sign.

Gary

In article , Gary Coffman says...

especially since the Griz doesn't have back gears.

Whoops. That would rate that particular machine a
'no thanks' for me, right there.

Jim

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

I spent several hours removing the shipping grease on my Enco 9x49" variable
speed mill, but that was all. It didn't require any repair.

Bill Ross writes:

Are old mills on the market for $2,500 likely to be worn out?

Very likely at that price.

My Bridgeport Series 1 price survey has been: $1500 for serviceable but
with severe wear or broken head, $2500 for running but with moderate to
severe wear, and $3500 and up for running with light to moderate wear.

How much is it going to cost to get them into good running shape?

I am now working myself on scraping a well-worn (e.g., middle of knee
concave by 0.005", gibs shimmed with pieces of crate strapping metal!)
Bridgeport. It has been quite educational and a project of making tools
and gages in itself. Quite a few $100s in cash to buy books and tools,
and quite a few hours making and improvising some of the tools. Getting
this kind of rebuild done right is perhaps $3000 to hire out, and you
probably have to ship the machine to get it in the hands of someone who
does it. I figured out why some of these old machines have such pretty
body-shop repaint jobs on them: the effort to do that is a small
fraction of the effort to get the machine back to factory alignment.

The most valuable lessons of all are that I am now become knowledgeable
at evaluating all aspects of Bridgeport wear. There's no way you can
work on repairing alignment without knowing everything there is to know
about measuring it first. Sometimes you learn the hard way. I spent a
week rough and finish scraping the knee ways, and then discovered my
datum surface was off.

I am also converting the ways to teflon bearings, which should make this
machine last forever before realignment is needed again.

The pricing on Bridgeport's vary greatly with location. I could find a VERY
good Bridgeport for $3000 it might take a few but they are out there. I some
locations that might not be possible.
As to the Griz, I would want to see one (same with the Bridgeport) before
buying. I looked at a 18" grizzly band saw just 2 days ago and was not very
impressed with its quality. Every part on the machine was as minimum as it
could be.
I own a Millport milling machine and its an import copy of a Bridgeport. I
use both mine and my dads Bridgeport and see no real difference. Take a look
www.motherearthrecycling.net/shop/shop.htm
But I was able to try before I buy, and the seller offered it to me at a
very LOW price.

In article , Richard J Kinch
says...

I am also converting the ways to teflon bearings, which should make this
machine last forever before realignment is needed again.

Teflon? You maybe mean turcite, or rulon.

Plain PTFE would be a poor choice for a way bearing
surface IMO.

Jim

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

--Lotsa good "old iron" out there; some of it not too worn out,
too. And remember there are some pretty reasonably priced ways to bring a
beater back to life, like replacing the bronze nut (forgot the proper
name) that the Acme screws run thru, or even just tightening up the old
one... If I had room for a Bridgeport-sized machine I'd start looking for
an old Webb. Used to operate one when I worked in So Calif; they're
massive, have more Y-axis travel than a standard Series 1 and you just
can't wear them out.

--
"Steamboat Ed" Haas : Somewhere in Texas a
Hacking the Trailing Edge! : village has lost an idiot...
http://www.nmpproducts.com/intro.htm
---Decks a-wash in a sea of words---

I have a few questions.

1. How did you conduct yor "Price Survey?" In the NY-NJ area I thought
$2500 was the very high end for a manual Series 1 machine. I knew
plenty of examples of one being sold for $500. Yes it is true not
every one is still in good shape, but if you can run a few operations
before you buy it, hop in the car and go see it.

Can someone recommend a good test regimen? Armed with this, does a non
expert really need to hire a technician?

2. Someone said that a vfd could be used as a speed control on a
Grizzly that runs on house current. That's wrong, right?

3. Is there anyone who would actually prefer a new Enco to a used but
sound BP? In '98 I bought both a 1979 series 1 cnc and a big Enco
lathe. I bet I spent fifty bucks just on band-aids from all the sharp
edges and burrs on the Enco. I also spent probably fifty hours just on
setup, adjustment and maintenance. In the end, it did do a lot of work
for me, and had a lot of guts, but I never overcame vibration problems
that left surface texture and increased finishing time. A guy down the
street, on the other hand had a very old, very big Clausing (12x60
maybe?)that was a dream machine. I used to rent time on it when
precision really mattered. I think he paid about $4000. $1200 more
than my Enco, but it came with a closet full of tooling and no plastic
drive gears.

The BP, on the other hand was true blue. The electronics on it were
****. After two $400 repair visits I invested in an Ah-ha controller.
That was very easy to install and get running. The machine
itself,however, ran like new. Ways, VSD, spindle bearings, steppers,
etc. I didn't even change the oil pump.

I have certainly used old BPs that WERE worn out. You need to spend
some time shopping, and be patient, informed, and a little lucky. In
my experience, low end imports like Grizzly and Enco will require tons
of service right from the start, and torture you for as long as you
own them. Good used domestic gear, on the other hand, in
non-industrial use, will easily outlive you!
Enough said.
Robobass


Richard J Kinch wrote in message ...
Bill Ross writes:

Are old mills on the market for $2,500 likely to be worn out?

Very likely at that price.

My Bridgeport Series 1 price survey has been: $1500 for serviceable but
with severe wear or broken head, $2500 for running but with moderate to
severe wear, and $3500 and up for running with light to moderate wear.

How much is it going to cost to get them into good running shape?

I am now working myself on scraping a well-worn (e.g., middle of knee
concave by 0.005", gibs shimmed with pieces of crate strapping metal!)
Bridgeport. It has been quite educational and a project of making tools
and gages in itself. Quite a few $100s in cash to buy books and tools,
and quite a few hours making and improvising some of the tools. Getting
this kind of rebuild done right is perhaps $3000 to hire out, and you
probably have to ship the machine to get it in the hands of someone who
does it. I figured out why some of these old machines have such pretty
body-shop repaint jobs on them: the effort to do that is a small
fraction of the effort to get the machine back to factory alignment.

The most valuable lessons of all are that I am now become knowledgeable
at evaluating all aspects of Bridgeport wear. There's no way you can
work on repairing alignment without knowing everything there is to know
about measuring it first. Sometimes you learn the hard way. I spent a
week rough and finish scraping the knee ways, and then discovered my
datum surface was off.

I am also converting the ways to teflon bearings, which should make this
machine last forever before realignment is needed again.

On Sun, 4 Jul 2004 08:51:43 -0400, "Wayne" makowicki wrote:

The pricing on Bridgeport's vary greatly with location. I could find a VERY
good Bridgeport for $3000 it might take a few but they are out there. I some
locations that might not be possible.

Hell yes. In California, you can get a nice one for $2500 WITH a DRO.

Though again..the trend is slowly reversing as industry starts
cranking up again after the recession.

Ebay was the first hard evidence that the economy was finally turning
as I watched the prices of DV-59s start to rise again.

Hummm I wonder if I should write a paper titled "Manufacturing in
America and the DV59 Index"

G

Gunner sitting inside for a few, and avoiding the 104 F temp @40%
humidity...brack!!!!!!!!!!!!!!!


That rifle hanging on the wall of the working-class flat or labourer's
cottage is the symbol of democracy. It is our job to see that it stays
there.
- George Orwell

On 4 Jul 2004 11:24:39 -0700, (robobass) wrote:
2. Someone said that a vfd could be used as a speed control on a
Grizzly that runs on house current. That's wrong, right?

Actually, someone (me) said exactly the opposite. You can't speed
control a 1 ph motor with a VFD. You *can* use a VFD to produce 3 ph
from 1 ph, allowing you to speed control a 3 ph motor in a shop which
is supplied with only 1 ph household power.

Gary

In article , Gunner says...

Ebay was the first hard evidence that the economy was finally turning
as I watched the prices of DV-59s start to rise again.

But probably most of those were being sold
for omni-turn conversions, right?

Jim

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

robobass wrote:


3. Is there anyone who would actually prefer a new Enco to a used but
sound BP?


You have experiences from 1979, but here are some posts from 2003:

http://www.google.com/groups?hl=en&l...nyroc.rr.co m
http://www.google.com/groups?hl=en&l...g.googl e.com



--
A society that teaches evolution as fact will breed a generation of atheists that will destroy the society. It is Darwinian.

On 4 Jul 2004 15:17:37 -0700, jim rozen
wrote:

In article , Gunner says...

Ebay was the first hard evidence that the economy was finally turning
as I watched the prices of DV-59s start to rise again.

But probably most of those were being sold
for omni-turn conversions, right?

Jim

Actually no, they are not. They are being put back into service in
the many small (often minority owned) machine shops that are starting
to spring up again.

I suspect the time of cheap machines is about over for a while. Cheap
great! machines that is.

Btw..a Harding Chucker (HC), DSMA, and AHC are probably the best for
putting Omniturns on. A very nice rigid retrofit capable of marvelous
work.


Gunner

That rifle hanging on the wall of the working-class flat or labourer's
cottage is the symbol of democracy. It is our job to see that it stays
there.
- George Orwell

I hate to jump in on this because I have an apparent conflict of
interst. I currently have a Bridgeport mill on ebay. I traded it
from a man who rents space in the same room I am in, in an old
factory. It was his manual backup mill, he uses a Lagun CNC most of
the time. He traded it to me for a mill with a 49" table. This one
has a 36" table. Opening bid is set at $1,800. Because it ends early
tomorrow, it will probably sell for the opening bid, if it sells at
all (the holiday factor). It is a very nice machine and has hard
chrome ways. There is nothing wrong with this mill, and it has a
Servo powerfeed on it. I traded him a Chinese Bridgeport clone for
it, so go figure that into the Chinese vs American iron argument.
He's a professional machinist with 30 tears experience. I don't
usually use this venue to mention product, but this is a good
Bridgeport, right in the price range mentioned. A little shipping and
you are at the $2,500 budget.
Paul
(papapault)

Now I do think there is a difference in Taiwanese tools and tools made in
China. I am FAR from an expert but I have seen some real CRAP from the China
makers, and very little good stuff. Just the other day I looked at a good
size drill press with a MT3 spindle that had a lot more play than my 50 year
old delta. Almost all of the stuff from China I see is of poor workmanship.
Now look at a Takasawi engine lathe that is Taiwanese made, and its a work
of art. My mill is Taiwanese and it is a very nice machine, its over 20
years old and has been used a good amount and it is still very tight. The
man I bought it from had both the Millport and a Bridgeport and said he used
the Millport more, its the mill he preferred to run. My father is a close
friend of the seller and had said for years that he liked the Millport more.
I now own the machine and am very happy with it.

Wayne wrote:

Now I do think there is a difference in Taiwanese tools and tools made in
China. I am FAR from an expert but I have seen some real CRAP from the China
makers, and very little good stuff.

I agree, there are many nuances.
The idea of "high tech" is really "new tech".
The long established industries moved from England to the US for cheaper
labor 200 years ago.
Now industries that anyone can do move from the US to Japan, from Japan
to Taiwan, and from Taiwan to China.
Higher up the chain gets higher quality, but higher prices.
25 years ago, I would have said, buy Bridgeport, but keep an eye on Jet
of Japan.
Right now I think Taiwan made cast iron machinery through Enco is the
best trade off between cost and quality for individual hobbyist.
Sometime in the future, China made will become the best quality per cost
deal.

--
A society that teaches evolution as fact will breed a generation of atheists that will destroy the society. It is Darwinian.

jim rozen writes:

Teflon? You maybe mean turcite, or rulon.

Plain PTFE would be a poor choice for a way bearing
surface IMO.

"Turcite" (not turcite) is just a brand name. My understanding is that
Turcite B is PTFE, and Turcite A or TA and TX or X are acetal-PTFE
copolymer. If you have some other information, I'd like to hear it.

In article ,
says...
jim rozen writes:

Teflon? You maybe mean turcite, or rulon.

Plain PTFE would be a poor choice for a way bearing
surface IMO.

"Turcite" (not turcite) is just a brand name. My understanding is that
Turcite B is PTFE, and Turcite A or TA and TX or X are acetal-PTFE
copolymer. If you have some other information, I'd like to hear it.


Both Turcite and Rulon are families of filled or reinforced
PTFEs. I don't believe any of the flavors are straight
Teflon. Both my mill and lathe have this stuff on the ways,
though I don't know whether it's turcite or rulon or
another brand. It's definitely not plain Teflon--it's much
harder and more resistant to abrasion and gouging.

I've never seen any credible evidence that these materials
last longer than a properly maintained traditional way, but
they do make a noticeably improvement in the "feel" of the
machine by reducing stiction.

Ned Simmons

In article , Richard J Kinch
says...

Plain PTFE would be a poor choice for a way bearing
surface IMO.

"Turcite" (not turcite) is just a brand name. My understanding is that
Turcite B is PTFE, and Turcite A or TA and TX or X are acetal-PTFE
copolymer. If you have some other information, I'd like to hear it.

The only information I *do* know is that pure PTFE cold-flows - a
lot. It would be a poor choice for way sliders.

Jim

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

jim rozen writes:

Plain PTFE would be a poor choice for a way bearing
surface IMO.

"Turcite" (not turcite) is just a brand name. My understanding is
that
Turcite B is PTFE, and Turcite A or TA and TX or X are acetal-PTFE
copolymer. If you have some other information, I'd like to hear it.

The only information I *do* know is that pure PTFE cold-flows - a
lot. It would be a poor choice for way sliders.

Yes, we've all seen that, but: do you have actual experience with PTFE
cold flowing in the low pressures of a machine way? I believe you are
confusing a high-pressure cold-flowing property with conditions in a
machine way.

The references I can find (such as the _Merck Index_ entry for PTFE, and
http://www.glenair.com/conduit/choose.pdf) state that PTFE cold flows
under *high pressures*. An example would be highly compressed regions
in gaskets. The pressures contemplated are 1000 psi or more.

Cast iron machine ways are designed with a meximum of 100 or 150 psi.
For example, a Bridgeport Series 1 saddle has about 27 sq in of bearing
surface, and worst-case loads would therefore be well under 100 psi, at
which level cold flow is a non-issue. The reason for this pressure
limit (well below the strength of the bearing itself) is to maintain oil
film lubrication.

I plan to run tests to prove this by just putting test masses on top of
test squares, and seeing what happens. I've already been testing the
material from MSC (vs Turcite B which is hard to get and exorbitantly
priced). For this I have been using cast iron angle plates, which I
scrape to 0.0001" flatness, but so far I have just been proving the
process of bonding with epoxy and getting a bearing-quality flatness on
the PTFE surface.

The manufacturer is cagey about just what Turcite B is, but it does
exactly match plain ol' PTFE's peculiarities in the published mechanical
properties. So my suspicion is that it is simply PTFE at a premium
price. There are no other candidate substances possible to my
knowledge. It isn't like there is some secret Coke formula involved.

I also speculate that some case of what is called "cold flow" are merely
ordinary plastic deformation. If you look at the low numbers of the
mechanical properties for PTFE, and considering the uniquely vanishing
coefficient of friction, then you can see how it would happen in many
applications. But not in machine ways by my analysis.

Another difference in machine ways is that the thin layer is bonded to
the relatively unyielding metal way. This eliminates any stresses from
forces accumulated across a long distance.

Ned Simmons writes:

Both Turcite and Rulon are families of filled or reinforced
PTFEs. I don't believe any of the flavors are straight
Teflon. Both my mill and lathe have this stuff on the ways,
though I don't know whether it's turcite or rulon or
another brand. It's definitely not plain Teflon--it's much
harder and more resistant to abrasion and gouging.

There is a bit of confusion going on here. There is more than one
material called "Turcite" (brand name). There are dozens of Rulon
varieties, involving PTFE with more or less other things. Turcite A
appears to be acetal-PTFE copolymer or blend (like Delrin AF brand),
which sounds like what you are describing. Another (Turcite B) is what
I suspect is PTFE alone, which is what the manufacturer suggests for
machine ways (they also call it "Slydway").

I've never seen any credible evidence that these materials
last longer than a properly maintained traditional way, but
they do make a noticeably improvement in the "feel" of the
machine by reducing stiction.

Plenty of evidence in the mfr literature. Polymers have certain
properties that improve life vs cast iron ways. Just lowering the
coefficient of friction significantly has to improve wear dramatically.
Since you have the metal underneath a thin layer of polymer, you get the
best of both, strength and rigidity of metal with lubricity and wear of
the polymer.

But the blockbuster benefit is that the cast iron components of the
bearing just doesn't wear at all, just the polymer layer, at least in
our lifetimes. When the polymer layer wears out of alignment, it is
replaceable in a relatively simple process. Compared to having to
rescrape and realign metal, that is an *immense* economy.

Richard J Kinch writes:

I've already been testing the
material from MSC (vs Turcite B which is hard to get and exorbitantly
priced).

By the way, this is what I've been testing, MSC item 32017774:

http://www.mscdirect.com/mscProductSearch.process?query=32017774

This 0.03125" thick and bonds with ordinary epoxy. At $27 for 2 sq ft you
have plenty to do a Bridgeport saddle with several retries.

In article , Richard J Kinch
says...

Yes, we've all seen that, but: do you have actual experience with PTFE
cold flowing in the low pressures of a machine way?

No. I've attempted to use teflon for small bearings, with
poor results.

Another reason to stay away from pure teflon is, it is very
tough to bond it using any regular adhesives.

Probably most commercial engineering polymers will show
mechanical properties somewhat similar to teflon, though
not the friction co-efficients, obviously.

My best guess would be to use teflon-loaded delrin
available inexpensively from mcmcaster carr. It will
exhibit pretty much the same slide characteristics
as pure teflon, but will not cold flow.

Jim

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

jim rozen writes:

Another reason to stay away from pure teflon is, it is very
tough to bond it using any regular adhesives.

You can't be referring to the MSC item I cited, which is treated on one
face to be bondable with ordinary epoxy.

My best guess would be to use teflon-loaded delrin
available inexpensively from mcmcaster carr. It will
exhibit pretty much the same slide characteristics
as pure teflon, but will not cold flow.

Delrin (trademark for acetal, capitals, likewise Teflon for PTFE) AF
(presumably abbreviation for "anti-friction", namely acetal with PTFE
component) does improve the structural properties, and comes close to pure
PTFE for dynamic friction, but does not come close to pure PTFE for the
static friction ("stiction"). Getting down around 0.04 static COF would
seem to be a huge improvement for CNC movements like tangents of curves
that have minimal motion in one axis vs another, where stiction causes
staircasing. From what I read this is what many CNC machine ways use for
just that purpose.

jim rozen writes:

"Turcite" (not turcite) is just a brand name. My understanding is that
Turcite B is PTFE, and Turcite A or TA and TX or X are acetal-PTFE
copolymer. If you have some other information, I'd like to hear it.

The only information I *do* know is that pure PTFE cold-flows - a
lot. It would be a poor choice for way sliders.

I just discovered this MSDS from the mfr which states the Turcite B is
indeed just PTFE:

http://www.mtsandtg.com/TurciteBSlydway.pdf

Richard J Kinch wrote:
jim rozen writes:
"Turcite" (not turcite) is just a brand name. My understanding is that
Turcite B is PTFE, and Turcite A or TA and TX or X are acetal-PTFE
copolymer. If you have some other information, I'd like to hear it.
The only information I *do* know is that pure PTFE cold-flows - a
lot. It would be a poor choice for way sliders.
I just discovered this MSDS from the mfr which states the Turcite B is
indeed just PTFE:

http://www.mtsandtg.com/TurciteBSlydway.pdf

I don't see it saying Turcite B is just PTFE. True, in section 2
it lists nothing besides PTFE (polytetrafluoroethylene) and
Chromium III Compound (0.5% by wt.) as hazardous ingredients.
But in section 8 it says "This compound contains Chromium III
compounds [...] and 25% Cu metal".
-jiw

James Waldby writes:

I don't see it saying Turcite B is just PTFE. True, in section 2
it lists nothing besides PTFE (polytetrafluoroethylene) and
Chromium III Compound (0.5% by wt.) as hazardous ingredients.
But in section 8 it says "This compound contains Chromium III
compounds [...] and 25% Cu metal".

MSDSs are government (regulatory) documents and you have to be careful
interpreting them for physical facts . There is just a tiny bit of the
metallic portion (0.5% total stated on the first page). This I suspect is
just the very thin coating on one face made by converting the pure PTFE to
a thin bondable layer. This is what makes the product glueable with epoxy.
Otherwise, nothing sticks to PTFE. It helps to have seen this stuff, snow
white PTFE on one face, a muddy brown on the other (the uncolored MSC
version).

The "25% Cu" appears to be a misprint. It should have been enclosed in the
parenthesis just preceding. That is, of the 0.5 percent chromium III
compounds, 25 percent of the weight of those compounds consist of Cu.

The point is, the bulk polymer is pure PTFE, not acetal, or something else.

In article ,
says...
Ned Simmons writes:

Both Turcite and Rulon are families of filled or reinforced
PTFEs. I don't believe any of the flavors are straight
Teflon. Both my mill and lathe have this stuff on the ways,
though I don't know whether it's turcite or rulon or
another brand. It's definitely not plain Teflon--it's much
harder and more resistant to abrasion and gouging.

There is a bit of confusion going on here. There is more than one
material called "Turcite" (brand name). There are dozens of Rulon
varieties, involving PTFE with more or less other things.

No confusion, note that I referred to Turcite and Rulon as
families of materials.

Turcite A
appears to be acetal-PTFE copolymer or blend (like Delrin AF brand),
which sounds like what you are describing.

It seems you're misusing the term copolymer. For example,
Delrin is an acetal homopolymer; Celcon an acetal
copolymer; Delrin AF is a mixture of Delrin and Teflon,
i.e., a PTFE filled acetal.

Another (Turcite B) is what
I suspect is PTFE alone, which is what the manufacturer suggests for
machine ways (they also call it "Slydway").

The manufacturer doesn't make this easy, do they? I'd be
very surprised if it was plain PTFE. Rulon 142, which is
claimed to be a direct replacement for Turcite B is
definitely *not* just PTFE. Also note that the specific
gravity of both Rulon 142 and Turcite B are considerably
higher (approx 3.1) than PTFE (about 2.2).


I've never seen any credible evidence that these materials
last longer than a properly maintained traditional way, but
they do make a noticeably improvement in the "feel" of the
machine by reducing stiction.

Plenty of evidence in the mfr literature.

Excuse me for being a bit sceptical of manufacturer's
claims. I have seen Turcite linear bearings (ball bushing
replacements) wear out. They certainly have their place,
but are not a panacea.

Polymers have certain
properties that improve life vs cast iron ways. Just lowering the
coefficient of friction significantly has to improve wear dramatically.
Since you have the metal underneath a thin layer of polymer, you get the
best of both, strength and rigidity of metal with lubricity and wear of
the polymer.

One thing that I worry about on my machines is the fact
that once grit or a particle gets imbedded in the plastic
it'll likely get dragged back and forth for a long time. My
mill has bellows way covers so is pretty well protected,
but the lathe has a dovetail bed with a nice wide flat
surface to catch anything that falls on it.

But the blockbuster benefit is that the cast iron components of the
bearing just doesn't wear at all, just the polymer layer, at least in
our lifetimes. When the polymer layer wears out of alignment, it is
replaceable in a relatively simple process. Compared to having to
rescrape and realign metal, that is an *immense* economy.

Sounds good in theory, we can compare notes on how it's
worked out in 30 or 40 years.g

Ned Simmons

In article ,
says...
James Waldby writes:

I don't see it saying Turcite B is just PTFE. True, in section 2
it lists nothing besides PTFE (polytetrafluoroethylene) and
Chromium III Compound (0.5% by wt.) as hazardous ingredients.
But in section 8 it says "This compound contains Chromium III
compounds [...] and 25% Cu metal".

MSDSs are government (regulatory) documents and you have to be careful
interpreting them for physical facts . There is just a tiny bit of the
metallic portion (0.5% total stated on the first page). This I suspect is
just the very thin coating on one face made by converting the pure PTFE to
a thin bondable layer. This is what makes the product glueable with epoxy.
Otherwise, nothing sticks to PTFE. It helps to have seen this stuff, snow
white PTFE on one face, a muddy brown on the other (the uncolored MSC
version).

The "25% Cu" appears to be a misprint. It should have been enclosed in the
parenthesis just preceding. That is, of the 0.5 percent chromium III
compounds, 25 percent of the weight of those compounds consist of Cu.

The point is, the bulk polymer is pure PTFE, not acetal, or something else.


See my earlier comment on the specific gravity of Turcite
B. The higher density would be consistent with a metal
filled PTFE.

Ned Simmons

Ned Simmons writes:

No confusion, note that I referred to Turcite and Rulon as
families of materials.

Right, I was confusing another's comment citing "turcite" as if it were
a single thing.

You did say they were filled or reinforced PTFE. I found one reference
today that identified one Rulon as ECTFE.

See my earlier comment on the specific gravity of Turcite
B. The higher density would be consistent with a metal
filled PTFE.

See my earlier reference to the MSDS, which doesn't list any metal
content in any proportion that would increase density.

But if you're right, then that would require about 10 to 15 percent
metal by volume, depending on the metal.

It seems you're misusing the term copolymer.

No, I said "copolymer or blend" (too lazy to check which). You're
correct, it is the latter.

Rulon 142, which is claimed to be a direct replacement for Turcite B
is
definitely *not* just PTFE.

So what is it, then?

One thing that I worry about on my machines is the fact
that once grit or a particle gets imbedded in the plastic
it'll likely get dragged back and forth for a long time.

They claim that is actually a benefit, that particles embed at or below
the surface so as to encapsulate and not wear the opposing metal.

And of course this is a problem with metal/metal bearings. There was a
deep score in the Bridgeport knee way I'm rescraping, and I eventually
discovered (only by the disassembly and scraping process) a single tiny
grain of carbide or diamond had been embedded in the opposing surface.

Ned Simmons writes:

See my earlier comment on the specific gravity of Turcite
B. The higher density would be consistent with a metal
filled PTFE.

Say, have a look at:

http://www.busakshamban.us/pdf/mds_t47.pdf

Turcite T47 == Bronze-filled PTFE w/ sp gr 3.02 to 3.14.

Lots more he

http://www.busakshamban.us/ref_library_global.htm?print=1

Seems the trademark "Turcite" applies to anything, pure PTFE, UHMW-PE,
bronze-filled, graphite-filled, carbon fiber, etc.

In article , Ned Simmons
says...


One thing that I worry about on my machines is the fact
that once grit or a particle gets imbedded in the plastic
it'll likely get dragged back and forth for a long time. My
mill has bellows way covers so is pretty well protected,
but the lathe has a dovetail bed with a nice wide flat
surface to catch anything that falls on it.

But isn't the ability of softer way sliders a plus? Then
the abrasive particle will simply embed deeper as time
goes on, whereas in cast iron/cast iron systems, it
will embed in something *hard* and keep on wearing
the bed ways?

Has anyone created bed sliders out if, say, brass or bronze?
If not, the reason probably is that they get charged as
a lap does, and will wear the harder bed rapidly.

Jim

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In article ,
says...
Ned Simmons writes:



Rulon 142, which is claimed to be a direct replacement for Turcite B
is
definitely *not* just PTFE.

So what is it, then?


-Rulon 142 not an insulator
http://www.rulon-
meldin.com/Data/Element/Node/ProductLine/product_line_edit.
asp?ele_ch_id=L0000000000000001708

-It's "TURQUOISE in color with a bronze tint."
http://www.boedeker.com/rulon_p.htm

-"Rulon ® is the Saint Gobain Performance Plastics
tradename for a family of reinforced proprietary PTFE
compounds."
http://www.boedeker.com/rulon_p.htm

-It's specific gravity is higher than any plastic I'm aware
of.

All admittedly circumstantial evidence, but I'd have to say
it's most likely a metal filled PTFE. Taking into account
the color and the Turcite B MSDS, probably a copper based
filler.

Ned Simmons

In article ,
says...
Ned Simmons writes:

See my earlier comment on the specific gravity of Turcite
B. The higher density would be consistent with a metal
filled PTFE.

Say, have a look at:

http://www.busakshamban.us/pdf/mds_t47.pdf

Turcite T47 == Bronze-filled PTFE w/ sp gr 3.02 to 3.14.

Makes you wonder why they're right out front with this and
there's so little info on the composition of Turcite B.


Lots more he

http://www.busakshamban.us/ref_library_global.htm?print=1

Seems the trademark "Turcite" applies to anything, pure PTFE, UHMW-PE,
bronze-filled, graphite-filled, carbon fiber, etc.


That's not too unusual. One of the best references on the
common engineering plastics I have is put out by Erta. They
list properties of acetal, various nylons, PET, etc., but
they're all called Erta(something).

Ned Simmons

In article ,
says...
In article , Ned Simmons
says...


One thing that I worry about on my machines is the fact
that once grit or a particle gets imbedded in the plastic
it'll likely get dragged back and forth for a long time. My
mill has bellows way covers so is pretty well protected,
but the lathe has a dovetail bed with a nice wide flat
surface to catch anything that falls on it.

But isn't the ability of softer way sliders a plus? Then
the abrasive particle will simply embed deeper as time
goes on, whereas in cast iron/cast iron systems, it
will embed in something *hard* and keep on wearing
the bed ways?

I've heard this claim for many different bearing materials
over the years, and while it makes sense to me that if the
offending particle is hard enough to wear a bearing surface
it's likely to be hard enough to embed in the mating
surface. And it makes sense if you're going to have an
embedded particle, it's better to have it stuck in a softer
rather than harder matrix. Nevertheless, it always troubles
me.

Quite a few years ago I was in the marine hardware
manufacturing business. One of our product lines was
stuffing boxes and stern bearings. We used a composite
plastic bearing rather the traditional rubber cutless
bearings in our stern bearings. Initially, most of these
were installed in lobster boats here in Maine where deep
water and muddy bottom is typical. When we started selling
more into southern New England, where shallower water is
the norm and sandy bottom more common, we started getting
complaints about excessive shaft wear. I never got a
definitive answer, but always assumed that the sand was
embedding in the plastic bearing, rather than flushing thru
like the rubber bearings. I realize this isn't a very good
analogy, but it's always made me leary of this sort of
claim.

It looks like the company now offers a composition
specifically for conditions where sand is suspended in the
water.
http://www.thordonbearings.com/3bii1.htm


Has anyone created bed sliders out if, say, brass or bronze?
If not, the reason probably is that they get charged as
a lap does, and will wear the harder bed rapidly.

I'm quite sure my old Rathbone chucker had bronze bushings
running on round ways, but that was a pretty unique
machine. It was a clone of a Hardinge chucker in that it
used the same turret and spindle tooling, but looked more
like the Monarch chuckers. In any case, having round ways
made it easier to exclude crud from the way bushings, so
the bronze didn't seem to be a problem. It was 40 years old
when I sold it, and it could easily work to a few tenths.

Ned Simmons

In article , Ned Simmons
says...

That's not too unusual. One of the best references on the
common engineering plastics I have is put out by Erta. They
list properties of acetal, various nylons, PET, etc., but
they're all called Erta(something).

I could also *highly* recommend a book called
"Engineering Polymer Sourcebook." By, umm...
hmm. Forgot the author's name. If there is
interest I will post it up in the morning, from
work.

Jim

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jim rozen writes:

I could also *highly* recommend a book called "Engineering Polymer
Sourcebook."

Wasn't the abridged version in _The Graduate_?

I'm loving those VFD's... Felt like Merlin himself when I hooked the latest one
up and it really produced 220 three phase from an 115 one phase household
current outlet... Sure seems like magic.

So much of single phase motors for me.

In article , Richard J Kinch
says...

jim rozen writes:

I could also *highly* recommend a book called "Engineering Polymer
Sourcebook."

Wasn't the abridged version in _The Graduate_?

:^)

"Engineering Polymer Sourcebook" by Raymond B. Seymour,
McGraw Hill, ISBN 0-07-056360-8.

Jim

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