On Mon, Apr 12, 2021 at 12:50 AM, Mark Kimball wrote:
Just beware that singularity when r = 0!!? Infinity is not something to mess with :)
LOL!? -- Regards, Charlie New Jersey, USA
SATTINGER¡¯S LAW: It works better if you plug it in.
EDWARD'S LAW: It works even better if you turn it on.
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I have tried to follow this thread, and the thing I see is a
question, HOW FOR HUNDREDS OF YEARS< HAVE MACHINISTS MANAGED TO
PART ITEMS IN A LATHE????? Answer SKILL!!
On 4/11/21 10:50 PM, Mark Kimball
wrote:
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When I'm parting or facing I (manually) crank up the RPMs as I
approach the center of the work.? Not for the "science" of cutting
as such, just so I don't have to slow the approach down a lot as I
approach the center.? If you're looking at what's going on it is
easy to see what's going on.? A CSS scheme could certainly help if
you're committed to an automation-based approach.? Just beware
that singularity when r = 0!!? Infinity is not something to mess
with :)
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When I'm parting or facing I (manually) crank up the RPMs as I approach the center of the work.? Not for the "science" of cutting as such, just so I don't have to slow the approach down a lot as I approach the center.? If you're looking at what's going on it is easy to see what's going on.? A CSS scheme could certainly help if you're committed to an automation-based approach.? Just beware that singularity when r = 0!!? Infinity is not something to mess with :)
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I had forgotten the discussions?we have had about CSS.
Gee you are only 3 hours away.
Ralph
On Sat, Apr 10, 2021 at 10:11 AM CLevinski < clevinski@...> wrote: Ralph,
I don't know what you meant by the following, then:
"I still find it strange to call it Constant Surface Speed when the speed is not constant."
I live in Middlesex County...
--
Regards,
Charlie
New Jersey, USA
SATTINGER¡¯S LAW: It works better if you plug it in.
EDWARD'S LAW: It works even better if you turn it on.
--
Clausing 8520, Craftsman 12x36 Lathe, 4x12 mini lathe, 14" Delta drill press, 40 watt laser, Consew brushless DC motors and a non working 3D printer
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Ralph, I don't know what you meant by the following, then: "I still find it strange to call it Constant Surface Speed when the speed is not constant." I live in Middlesex County... -- Regards, Charlie New Jersey, USA
SATTINGER¡¯S LAW: It works better if you plug it in.
EDWARD'S LAW: It works even better if you turn it on.
|
Thanks Charlie, DUH, I knew that. But I appreciate the refresher.
Where are you in NJ? I am out on Long Island on the East End.
Ralph
Ralph,
The RPMs are not constant, but the surface speed is... or, more accurately, in this system it is approximately constant between two limits.
This is an extremely important concept to understand. The ratings of cutting tool technologies, etc. are all based on the surface speed, I.E., how quickly the material being machined moves under the cutter. In a lathe, this depends on how far from the centerline the tool is cutting, and is most visible when facing.
Assume a simple round 4 inches in diameter being faced at a rotation rate of 100 RPM. When you start cutting at 2 inches from the centerline, the surface speed is:
100 r/m X 4 inches X pi = 1257 inches/min (approx)
When you are 1 inch from the centerline, the surface speed is:
100 r/m X 2 inches X pi = 628 inches/min (approx)
And when you are 1/4 inch from the centerline:
100 r/m x 0.5 inches X pi = 157 inches/min (approx)
Please note that the distance from the centerline for a round part is the radius. The circumference of the part is the diameter X pi, so we multiply the radius X 2 in the calculation.
The purpose of a constant surface speed system is to increase the RPMs to keep the surface speed constant during cutting.
BTW, have you ever noticed when facing that when you are almost to the centerline the the chips come off so slowly that you can watch each one form? That's because the surface speed decreases rapidly as you approach the centerline, and is? actually zero at the centerline. This is a problem for CSS systems, because the RPMs should approach infinity as the tool approaches the centerline in order to maintain constant surface speed, and very few spindle bearings are rated for infinity RPM.
--
Regards,
Charlie
New Jersey, USA
SATTINGER¡¯S LAW: It works better if you plug it in.
EDWARD'S LAW: It works even better if you turn it on.
--
Clausing 8520, Craftsman 12x36 Lathe, 4x12 mini lathe, 14" Delta drill press, 40 watt laser, Consew brushless DC motors and a non working 3D printer
|
Ralph, The RPMs are not constant, but the surface speed is... or, more accurately, in this system it is approximately constant between two limits. This is an extremely important concept to understand. The ratings of cutting tool technologies, etc. are all based on the surface speed, I.E., how quickly the material being machined moves under the cutter. In a lathe, this depends on how far from the centerline the tool is cutting, and is most visible when facing. Assume a simple round 4 inches in diameter being faced at a rotation rate of 100 RPM. When you start cutting at 2 inches from the centerline, the surface speed is: 100 r/m X 4 inches X pi = 1257 inches/min (approx) When you are 1 inch from the centerline, the surface speed is: 100 r/m X 2 inches X pi = 628 inches/min (approx) And when you are 1/4 inch from the centerline: 100 r/m x 0.5 inches X pi = 157 inches/min (approx) Please note that the distance from the centerline for a round part is the radius. The circumference of the part is the diameter X pi, so we multiply the radius X 2 in the calculation. The purpose of a constant surface speed system is to increase the RPMs to keep the surface speed constant during cutting. BTW, have you ever noticed when facing that when you are almost to the centerline the the chips come off so slowly that you can watch each one form? That's because the surface speed decreases rapidly as you approach the centerline, and is? actually zero at the centerline. This is a problem for CSS systems, because the RPMs should approach infinity as the tool approaches the centerline in order to maintain constant surface speed, and very few spindle bearings are rated for infinity RPM. -- Regards, Charlie New Jersey, USA
SATTINGER¡¯S LAW: It works better if you plug it in.
EDWARD'S LAW: It works even better if you turn it on.
|
I still find it strange to call it Constant Surface Speed when the speed is not constant.
I saw an ad for a $500,00 lathe that programmable variable?spindle speed was a big part of their promotion, I cannot remember?the lathe name.
Ralph
I found this video on you tube, my wife took possibly 5 years ago and sorry not Hollywood but hopefully shows the invaluable use
of my Constant Surface Speed attachment.?
I fitted to a real Bull Lathe with gear reduction, and advised it can be also compatible for the Sieg type mini lathes.
Just need to be careful with the Sieg that the spindle does not start turning on its own.
This possibility is detailed in the instructions in the Digital hobbyist files created by C Levinski
The lathe since has gone through several more digital age changes, including the RELS, compound slide removed etc.
Hope of interest.
--
John
--
Clausing 8520, Craftsman 12x36 Lathe, 4x12 mini lathe, 14" Delta drill press, 40 watt laser, Consew brushless DC motors and a non working 3D printer
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Just a comment about the CSS that John is referring to here. There are much more sophisticated ways to implement a CSS than what John and I did here, but he wanted a very simple to assemble and? retrofit system at the time. (John's electronic skills have improved significantly since then!) Basically, in this system, a linear potentiometer with upper and lower limit pots replaces the lathe's speed control. An analysis of the values used showed that the RPM was accurate to 5% for most of the travel, especially at the extremes, as shown in John's video. The speed theoretically should go to infinity at the center of the work, so obviously the error increases as one gets near the centerline. The CSS is most valuable for facing larger diameter parts, as John has demonstrated in his video. Also, please note that the issue of the spindle being able to start when power is applied is an issue with Sieg AND Real Bull lathes. Please check the instructions for warnings on this issue and use caution when operating! -- Regards, Charlie New Jersey, USA
SATTINGER¡¯S LAW: It works better if you plug it in.
EDWARD'S LAW: It works even better if you turn it on.
|
Greg, thanks, lots to work through regarding my mechanical? tinkering of ideas from the past, mini lathe and mill and 3D printing. Much?appreciated? is the help and patience from Richard and Charlie on the "lecky" side of new designs. My problem being, if I cannot see things move, I am clueless. I cannot see lecky current moving but I have felt it move many times LOL OUCH.
Dear John,
I'm your 18th subscriber and looking forward to a weekly video update! Your a man of many talents
Fair well Greg
--
John
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Dear John,
I'm your 18th subscriber and looking forward to a weekly video update! Your a man of many talents
Fair well Greg
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Greg and members, Ref you tube postings.
Just doing a spring clean on my computer and found this.maybe of interest.
This was me machining more gear reduction motor mounting brackets for Real Bull lathes, Sietg have?
different type motor end plates, but Robert Furmanak of Florida owns a Sieg mini lathe and had? good success with his design many years ago.
Video : Expanation, an aluminium billet boled to a face plate, 25 mm eccentricity, 3 mm deep cuts.80 mm final diameter,?using my 2:1 reduction ratio. GR now double the torque with a loss of almost 45%of top RPM.
Max RPM of the Real Bull from the factory 2500 RPM, Crazy speeds for a metal turner like me , or even wood.
machinst, 100 mm chuck running at 2500 RPM, IMHO, not safe.
So far, I have supplied a total of 6 gear reduction units worldwide for Real Bull lathes, all seem happy?
campers in its use.?
More info is available in the digitalhobbyist forum under hashtag #GR
Naturally my first prototype motor bracket was machined with the original power supplied from the factory supplied lathe, what a SLOW job that was.
Hope of interest, and inspires forum members of future projects.
Regards
John Lindo
--
John
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I found this video on you tube, my wife took possibly 5 years ago and sorry not Hollywood but hopefully shows the invaluable use
of my Constant Surface Speed attachment.
I fitted to a real Bull Lathe with gear reduction, and advised it can be also compatible for the Sieg type mini lathes.
Just need to be careful with the Sieg that the spindle does not start turning on its own.
This possibility is detailed in the instructions in the Digital hobbyist files created by C Levinski
The lathe since has gone through several more digital age changes, including the RELS, compound slide removed etc.
Hope of interest.
--
John
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---------- Forwarded message --------- From: John Lindo <bechetboat@...>Date: Thu, 8 Apr 2021 at 18:31 Subject: Re: [digitalhobbyist] Swing up tool holder files #MISC #MODS #LATHES #file-notice To: < [email protected]> Good question. Charlie
The?drawing shows a pin on the swinging?arm and in the block there is a accurately?positioned slot. It used to be the thrust stop when cutting left hand threads, IE The tool going away from the chuck, this?early design reduced the bending forces being applied on the bearing pin. This was my first approach before I modified to add on the thrust plate. Now the pin/ slot are optional or use this method and not?use?the thrust plate. You do not need both designs.? I left?it in on my original drawings, also this pin is visible in some of the recent photos sent to the forum.
Thanks for your interest.
John
John,
What is the purpose of the two "Optional Rods" shown in the "Swinging Tool Holder External.pdf" file?
--
Regards,
Charlie
New Jersey, USA
SATTINGER¡¯S LAW: It works better if you plug it in.
EDWARD'S LAW: It works even better if you turn it on.
--
John
|
??? ??? thanks John
??? ??? animal
On 4/8/2021 12:00 AM, John Lindo wrote:
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Show quoted text
I have added two files in the Files section.
Generic dimensioning as each? lathe and toolost holder will be
different
I useed a 626Z bearing.
Any extra info required then please post.
--
John
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Good question.
The?drawing shows a pin on the swinging?arm and in the block there is a accurately?positioned slot. It used to be the thrust stop when cutting left hand threads, IE The tool going away from the chuck, this?early design reduced the bending forces being applied on the bearing pin. This was my first approach before I modified to add on the thrust plate. Now the pin/ slot are optional or use this method and not?use?the thrust plate. You do not need both designs.? I left?it in on my original drawings, also this pin is visible in some of the recent photos sent to the forum.
Thanks for your interest.
John
John,
What is the purpose of the two "Optional Rods" shown in the "Swinging Tool Holder External.pdf" file?
--
Regards,
Charlie
New Jersey, USA
SATTINGER¡¯S LAW: It works better if you plug it in.
EDWARD'S LAW: It works even better if you turn it on.
--
John
|
John, What is the purpose of the two "Optional Rods" shown in the "Swinging Tool Holder External.pdf" file? -- Regards, Charlie New Jersey, USA
SATTINGER¡¯S LAW: It works better if you plug it in.
EDWARD'S LAW: It works even better if you turn it on.
|
I have added two files in the Files section.
Generic dimensioning as each? lathe and toolost holder will be different
I useed a 626Z bearing.
Any extra info required then please post.
--
John
|
The following files have been uploaded to
the Files area of the [email protected] group.
By: John Lindo <bechetboat@...>
Description:
Swinging Tool Holder Ext and Int byJohn Lindo
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Thanks John, the motorized Z drive system I am close to implementing AtomicELS?does not have a X component.
So the swinging?tool holder is high on my list.
I hope to modify AtomicELS for X but that would require a lot of help from my friends.
Once I get motorized X I will install RELS. I'd also like to try some of the newer versions from Oleg's ELS.
Ralph
On Tue, Apr 6, 2021 at 12:54 PM mike allen < animal@...> wrote:
??? ??? Thank you John
??? ??? animal
On 4/5/2021 8:51 PM, John Lindo wrote:
I
will post the pdf files of the swinging tool holder into
digitalhobbyist later this week.
Thanks
for all of your interest.
John
Lindo
Hi,
John,
I had a couple of other photos that you had sent me at the
time that I thought might be of interest...
--
Clausing 8520, Craftsman 12x36 Lathe, 4x12 mini lathe, 14" Delta drill press, 40 watt laser, Consew brushless DC motors and a non working 3D printer
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John Lindo