My friend told me that he saw something written somewhere that
Bridgeport Interacts cannot mill (bore) a precisely round hole,
because of stretch on the servo motor timing belts. What do you think
about this statement.

i

Ignoramus6705 fired this volley in
:

My friend told me that he saw something written somewhere that
Bridgeport Interacts cannot mill (bore) a precisely round hole,
because of stretch on the servo motor timing belts. What do you think
about this statement.


I think that for any given feed vector, you could calculate (or measure
empirically) the stretch, and have a lookup table that adjusted the feed
to compensate. That would probably be a difficult programming job, but
anything is do-able. Back in the early 80's, I wrote Z-80 code that
would allow a bar code wand to scan a code at _widely_ varying speeds
within the body of the symbol (over 20:1 and varying rapidly), and still
decode it reliably. This is that sort of task. A wide range of feed
rates and feed depths would need to be accommodated, and you'd even have
to account for materials in the adjustments -- but it's just software.

I'm not sure what EMC enables you to do in that respect, but since it's
open-source, it's extensible.

The stretch on a belt is not immeasurable, but with modern Kevlar
reinforced belting, I think it would be minimal (supposing the belt is
not used near its design limits). I don't think the BP guys would have
liked not being able to mill round pockets. No... I don't think they'd
have settled for it, at all. Probably, their belts weren't 40 years old,
either G.

LLoyd

On Wed, 28 Jul 2010 19:08:24 -0500, Ignoramus6705
wrote:

My friend told me that he saw something written somewhere that
Bridgeport Interacts cannot mill (bore) a precisely round hole,
because of stretch on the servo motor timing belts. What do you think
about this statement.

i

Hey Iggy,

If it isn't "round", it isn't "belt stretch" !! If it's something to
do with the belts and pulleys, it may be wear, but not stretch.

How does yours do?

Brian Lawson

On 2010-07-29, Lloyd E. Sponenburgh lloydspinsidemindspring.com wrote:
Ignoramus6705 fired this volley in
:

My friend told me that he saw something written somewhere that
Bridgeport Interacts cannot mill (bore) a precisely round hole,
because of stretch on the servo motor timing belts. What do you think
about this statement.


I think that for any given feed vector, you could calculate (or measure
empirically) the stretch, and have a lookup table that adjusted the feed
to compensate. That would probably be a difficult programming job, but
anything is do-able.

Good point. Stretch is proportional to current.

Back in the early 80's, I wrote Z-80 code that
would allow a bar code wand to scan a code at _widely_ varying speeds
within the body of the symbol (over 20:1 and varying rapidly), and still
decode it reliably. This is that sort of task. A wide range of feed
rates and feed depths would need to be accommodated, and you'd even have
to account for materials in the adjustments -- but it's just software.

I'm not sure what EMC enables you to do in that respect, but since it's
open-source, it's extensible.

The stretch on a belt is not immeasurable, but with modern Kevlar
reinforced belting, I think it would be minimal (supposing the belt is
not used near its design limits). I don't think the BP guys would have
liked not being able to mill round pockets. No... I don't think they'd
have settled for it, at all. Probably, their belts weren't 40 years old,
either G.

Well, my mill is 23 years old and belts are fairly well tensioned.

i

"Ignoramus6705" wrote in message
...
My friend told me that he saw something written somewhere that
Bridgeport Interacts cannot mill (bore) a precisely round hole,
because of stretch on the servo motor timing belts. What do you think
about this statement.

i

You'll never CNC Gcode to bore accuracy. You'd have to check your machine
but a circle to +/- .002 with G02/03 would be awful good for your machine.
For accurate bores get a boring bar. I'm partial to devleig microbore - they
do 2 tenths easily and I own a complete set from .250" to over 6.0". I
lock the gibs down tight while boring to get this.

http://cgi.ebay.com/DEVLIEG-HEAVY-ME...item359fdc41ac

On Wed, 28 Jul 2010 19:08:24 -0500, Ignoramus6705
wrote:

My friend told me that he saw something written somewhere that
Bridgeport Interacts cannot mill (bore) a precisely round hole,
because of stretch on the servo motor timing belts. What do you think
about this statement.

i
define "precisely round"

Gunner

One could not be a successful Leftwinger without realizing that,
in contrast to the popular conception supported by newspapers
and mothers of Leftwingers, a goodly number of Leftwingers are
not only narrow-minded and dull, but also just stupid.
Gunner Asch

"Ignoramus6705" wrote in message
...
My friend told me that he saw something written somewhere that
Bridgeport Interacts cannot mill (bore) a precisely round hole,
because of stretch on the servo motor timing belts. What do you think
about this statement.

i

I would think it is minimal since an entire turn of the handwheel is 0.2" or
so. I would guess belt stretch to make less than a half thou difference.
But if it does affect your parts, you have the capability to put DRO scales
on your mill and use them with EMC2 instead of the motor encoders. That's
what my mill has, an Anilam control with Anilam DRO scales , the motors have
tachometers on them, they are stable even with backlash.

Have you found me a Syncrowave yet? :-)

RogerN

On 2010-07-29, RogerN wrote:

"Ignoramus6705" wrote in message
...
My friend told me that he saw something written somewhere that
Bridgeport Interacts cannot mill (bore) a precisely round hole,
because of stretch on the servo motor timing belts. What do you think
about this statement.

i

I would think it is minimal since an entire turn of the handwheel is 0.2" or
so. I would guess belt stretch to make less than a half thou difference.
But if it does affect your parts, you have the capability to put DRO scales
on your mill and use them with EMC2 instead of the motor encoders. That's
what my mill has, an Anilam control with Anilam DRO scales , the motors have
tachometers on them, they are stable even with backlash.

Roger, there is no handweel attached to the ballscrews.

Have you found me a Syncrowave yet? :-)

I had one for sale for $600 last year. I asked for 600 here and 750
elsewhere. No one from this newsgroup wanted it, so I sold it for $750.

i

RogerN wrote:

"Ignoramus6705" wrote in message
...
My friend told me that he saw something written somewhere that
Bridgeport Interacts cannot mill (bore) a precisely round hole,
because of stretch on the servo motor timing belts. What do you think
about this statement.

i

I would think it is minimal since an entire turn of the handwheel is 0.2" or
so. I would guess belt stretch to make less than a half thou difference.
But if it does affect your parts, you have the capability to put DRO scales
on your mill and use them with EMC2 instead of the motor encoders. That's
what my mill has, an Anilam control with Anilam DRO scales , the motors have
tachometers on them, they are stable even with backlash.

Have you found me a Syncrowave yet? :-)

RogerN

He could also move his current encoders to be directly connected to the
ballscrews, eliminating any possible belt issues from the positioning
accuracy. He would cut the counts per inch in half, but I think it's
high enough not to matter.

"Pete C." wrote in message
ster.com...

RogerN wrote:

"Ignoramus6705" wrote in message
...
My friend told me that he saw something written somewhere that
Bridgeport Interacts cannot mill (bore) a precisely round hole,
because of stretch on the servo motor timing belts. What do you think
about this statement.

i

I would think it is minimal since an entire turn of the handwheel is 0.2"
or
so. I would guess belt stretch to make less than a half thou difference.
But if it does affect your parts, you have the capability to put DRO
scales
on your mill and use them with EMC2 instead of the motor encoders.
That's
what my mill has, an Anilam control with Anilam DRO scales , the motors
have
tachometers on them, they are stable even with backlash.

Have you found me a Syncrowave yet? :-)

RogerN

He could also move his current encoders to be directly connected to the
ballscrews, eliminating any possible belt issues from the positioning
accuracy. He would cut the counts per inch in half, but I think it's
high enough not to matter.

My Anilam lathemate lathe does that, the encoders are coupled to the
ballscrew.

RogerN

On 2010-07-29, Pete C. wrote:

RogerN wrote:

"Ignoramus6705" wrote in message
...
My friend told me that he saw something written somewhere that
Bridgeport Interacts cannot mill (bore) a precisely round hole,
because of stretch on the servo motor timing belts. What do you think
about this statement.

i

I would think it is minimal since an entire turn of the handwheel is 0.2" or
so. I would guess belt stretch to make less than a half thou difference.
But if it does affect your parts, you have the capability to put DRO scales
on your mill and use them with EMC2 instead of the motor encoders. That's
what my mill has, an Anilam control with Anilam DRO scales , the motors have
tachometers on them, they are stable even with backlash.

Have you found me a Syncrowave yet? :-)

RogerN

He could also move his current encoders to be directly connected to the
ballscrews, eliminating any possible belt issues from the positioning
accuracy. He would cut the counts per inch in half, but I think it's
high enough not to matter.

Early on I have decided not to alter the hardware of this mill. What I
am doing is relatively simple. Changing hardware is complicated and
will ultimately ruin this mill due to my incompetence.

i

"Ignoramus6705" wrote in message
...
On 2010-07-29, RogerN wrote:

"Ignoramus6705" wrote in message
...
My friend told me that he saw something written somewhere that
Bridgeport Interacts cannot mill (bore) a precisely round hole,
because of stretch on the servo motor timing belts. What do you think
about this statement.

i

I would think it is minimal since an entire turn of the handwheel is 0.2"
or
so. I would guess belt stretch to make less than a half thou difference.
But if it does affect your parts, you have the capability to put DRO
scales
on your mill and use them with EMC2 instead of the motor encoders.
That's
what my mill has, an Anilam control with Anilam DRO scales , the motors
have
tachometers on them, they are stable even with backlash.

Roger, there is no handweel attached to the ballscrews.

OK, one turn of the ballscrew.

Have you found me a Syncrowave yet? :-)

I had one for sale for $600 last year. I asked for 600 here and 750
elsewhere. No one from this newsgroup wanted it, so I sold it for $750.

i

I've found some on eBay for over $2000 but I'm not that interested in one.
If I put my old one on a trailer to I can move it to my current address then
it will probably be sufficient. When I got it I ran some beads on aluminum
but had some trouble welding 2 pieces together, a stainless steel brush and
some more practice would have probably done the trick. I'm hoping to get a
tank of Argon soon but for right now I should concentrate on getting the
truck done and sold.

RogerN

Ignoramus6705 wrote:

On 2010-07-29, RogerN wrote:

"Ignoramus6705" wrote in message
...
My friend told me that he saw something written somewhere that
Bridgeport Interacts cannot mill (bore) a precisely round hole,
because of stretch on the servo motor timing belts. What do you think
about this statement.

i

I would think it is minimal since an entire turn of the handwheel is 0.2" or
so. I would guess belt stretch to make less than a half thou difference.
But if it does affect your parts, you have the capability to put DRO scales
on your mill and use them with EMC2 instead of the motor encoders. That's
what my mill has, an Anilam control with Anilam DRO scales , the motors have
tachometers on them, they are stable even with backlash.

Roger, there is no handweel attached to the ballscrews.

No, but his point was the one full revolution of the ballscrew is a
pretty small movement, and any belt stretch issues aren't likely to
cause more than a couple degrees of ballscrew position error. I think
you said 2.5mm ballscrew pitch, so perhaps something like 0.0006"
positioning error under belt stretch? Backlash and proper backlash
compensation will be a much bigger factor in accurate circular
interpolation.

On 2010-07-29, Ignoramus6705 wrote:
On 2010-07-29, RogerN wrote:

[ ... ]

I would think it is minimal since an entire turn of the handwheel is 0.2" or
so. I would guess belt stretch to make less than a half thou difference.
But if it does affect your parts, you have the capability to put DRO scales
on your mill and use them with EMC2 instead of the motor encoders. That's
what my mill has, an Anilam control with Anilam DRO scales , the motors have
tachometers on them, they are stable even with backlash.

Roger, there is no handweel attached to the ballscrews.

The "virtual" handwheel. :-) It is still 0.200" per revolution
of the ballscrew or the nut.

If yours is like mine -- the ballscrew for the X-axis does not
rotate at all -- instead the ball *nut* rotates in matched bearings.
And the ballscrew has a telescoping flat spring steel cover to keep
swarf off of it.

Y-axis, however, does have a rotating ballscrew.

BTW -- looking at the photo you just (re)posted of the mill on
the truck or trailer I now see that the Y-axis motor has the pulley end
towards the vertical ways in the back instead of facing out towards the
operator as mine does. I still should be able to mount the motor on the
side of the knee -- if I can find a flat enough surface. :-)

Enjoy,
DoN.

--
Remove oil spill source from e-mail
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

Ignoramus6705 wrote:
My friend told me that he saw something written somewhere that
Bridgeport Interacts cannot mill (bore) a precisely round hole,
because of stretch on the servo motor timing belts. What do you think
about this statement.
Baloney! Now, there is some tiny amount of stretch to the belts, but it
is certainly small, in the fractions of a thousandth of an inch.
I can't say about a Series-II BOSS machine, but there are other sources
of apparent backlash. There's compressibility of the screw, rocking of
the table when direction reverses, the constraint of the bearings that
hold the rotating nut, and so on. My gut feeling is that these other
sources of backlash, PLUS finite servo amplifier gain, will be much
greater than the belt stretch. It almost certainly adds up to several
tenths of a thousandth of an inch, and on an older machine, could be
much worse. if the preload on the ballscrew has all worn off, then it
will be in the several thousandth of an inch region.

If you need a really accurate and round bore, for a bearing or an engine
cylinder, you'll never get it on anything but a VERY high-end machine
tool in tip-top condition. When I do any sort of precision bore, I use
a boring head for the final finish. This WILL be round.

I have heard of people in the industry with $100,000+++ machines that
DO, indeed, mill precision bores in production. But, they have
specially tested these machines to be capable of maintaining that level
of precision and lack of backlash, and maintain them to keep them
performing at that level.

Jon

Ignoramus6705 wrote:
My friend told me that he saw something written somewhere that
Bridgeport Interacts cannot mill (bore) a precisely round hole,
because of stretch on the servo motor timing belts. What do you think
about this statement.

Oh, and finally, if you don't have a Renishaw ball-bar tester, you just
don't have the gear to find out what your machine really is capable of.
You can try milling a bore and measuring the fit, or sweeping the ID
with a tenth-reading DTI, but that will only give you a rough idea.

Jon

"Ignoramus6705" wrote in message
...
On 2010-07-29, RogerN wrote:

"Ignoramus6705" wrote in message
...
snip

Roger, there is no handweel attached to the ballscrews.

Have you found me a Syncrowave yet? :-)

I had one for sale for $600 last year. I asked for 600 here and 750
elsewhere. No one from this newsgroup wanted it, so I sold it for $750.

i

I saw you had them listed but by that time you had already changed your mind
about selling it. I found a Syncrowave 350 on eBay around 400 miles away
with a 499 starting bid and no reserve. Bigger than I want but a syncrowave
250 isn't exactly portable either. If freight isn't too high for 400 miles
I may bid $750 minus freight charges, thinking it would be worth $750
delivered. It doesn't have the TIG torch, water cooler, and I didn't see a
foot pedal. I already have a torch and water cooler on my old TIG so I'm ok
there. If I knew the foot pedal specifics I could probably get my existing
foot pedal to work on the Syncrowave too.

RogerN

On 2010-07-31, RogerN wrote:

"Ignoramus6705" wrote in message
...
On 2010-07-29, RogerN wrote:

"Ignoramus6705" wrote in message
...
snip

Roger, there is no handweel attached to the ballscrews.

Have you found me a Syncrowave yet? :-)

I had one for sale for $600 last year. I asked for 600 here and 750
elsewhere. No one from this newsgroup wanted it, so I sold it for $750.

i

I saw you had them listed but by that time you had already changed your mind
about selling it. I found a Syncrowave 350 on eBay around 400 miles away
with a 499 starting bid and no reserve. Bigger than I want but a syncrowave
250 isn't exactly portable either. If freight isn't too high for 400 miles
I may bid $750 minus freight charges, thinking it would be worth $750
delivered. It doesn't have the TIG torch, water cooler, and I didn't see a
foot pedal. I already have a torch and water cooler on my old TIG so I'm ok
there. If I knew the foot pedal specifics I could probably get my existing
foot pedal to work on the Syncrowave too.

Foot pedals are very simple. I actually have a pile of them.

i

"Ignoramus28671" wrote in message
...
On 2010-07-31, RogerN wrote:

"Ignoramus6705" wrote in message
...
On 2010-07-29, RogerN wrote:

"Ignoramus6705" wrote in message
...
snip

Roger, there is no handweel attached to the ballscrews.

Have you found me a Syncrowave yet? :-)

I had one for sale for $600 last year. I asked for 600 here and 750
elsewhere. No one from this newsgroup wanted it, so I sold it for $750.

i

I saw you had them listed but by that time you had already changed your
mind
about selling it. I found a Syncrowave 350 on eBay around 400 miles away
with a 499 starting bid and no reserve. Bigger than I want but a
syncrowave
250 isn't exactly portable either. If freight isn't too high for 400
miles
I may bid $750 minus freight charges, thinking it would be worth $750
delivered. It doesn't have the TIG torch, water cooler, and I didn't see
a
foot pedal. I already have a torch and water cooler on my old TIG so I'm
ok
there. If I knew the foot pedal specifics I could probably get my
existing
foot pedal to work on the Syncrowave too.

Foot pedals are very simple. I actually have a pile of them.

i

Do you know if the Syncrowave 350 is the same as the 250 beside the extra
weight and amps? Just wondering if I should bid on this item, assuming
freight is reasonable, or wait for something closer or a syncrowave 250.

RogerN

On 2010-07-31, RogerN wrote:

"Ignoramus28671" wrote in message
...
On 2010-07-31, RogerN wrote:

"Ignoramus6705" wrote in message
...
On 2010-07-29, RogerN wrote:

"Ignoramus6705" wrote in message
...
snip

Roger, there is no handweel attached to the ballscrews.

Have you found me a Syncrowave yet? :-)

I had one for sale for $600 last year. I asked for 600 here and 750
elsewhere. No one from this newsgroup wanted it, so I sold it for $750.

i

I saw you had them listed but by that time you had already changed your
mind
about selling it. I found a Syncrowave 350 on eBay around 400 miles away
with a 499 starting bid and no reserve. Bigger than I want but a
syncrowave
250 isn't exactly portable either. If freight isn't too high for 400
miles
I may bid $750 minus freight charges, thinking it would be worth $750
delivered. It doesn't have the TIG torch, water cooler, and I didn't see
a
foot pedal. I already have a torch and water cooler on my old TIG so I'm
ok
there. If I knew the foot pedal specifics I could probably get my
existing
foot pedal to work on the Syncrowave too.

Foot pedals are very simple. I actually have a pile of them.

i

Do you know if the Syncrowave 350 is the same as the 250 beside the extra
weight and amps? Just wondering if I should bid on this item, assuming
freight is reasonable, or wait for something closer or a syncrowave 250.

It is an older and different machine. I resold one before (bought for
$200 sold for $800) ask ernie.

i

On Sat, 31 Jul 2010 09:33:35 -0500, Ignoramus28671
wrote:

On 2010-07-31, RogerN wrote:

"Ignoramus6705" wrote in message
...
On 2010-07-29, RogerN wrote:

"Ignoramus6705" wrote in message
...
snip

Roger, there is no handweel attached to the ballscrews.

Have you found me a Syncrowave yet? :-)

I had one for sale for $600 last year. I asked for 600 here and 750
elsewhere. No one from this newsgroup wanted it, so I sold it for $750.

i

I saw you had them listed but by that time you had already changed your mind
about selling it. I found a Syncrowave 350 on eBay around 400 miles away
with a 499 starting bid and no reserve. Bigger than I want but a syncrowave
250 isn't exactly portable either. If freight isn't too high for 400 miles
I may bid $750 minus freight charges, thinking it would be worth $750
delivered. It doesn't have the TIG torch, water cooler, and I didn't see a
foot pedal. I already have a torch and water cooler on my old TIG so I'm ok
there. If I knew the foot pedal specifics I could probably get my existing
foot pedal to work on the Syncrowave too.

Foot pedals are very simple. I actually have a pile of them.

i

So to I. Probably....6-8 of them




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