Richard

#725

Constant Surface Speed has been mentioned a few times on this and other
groups. Whilst I am fully aware of what it is I am not aware of how it
is handled in the real world.
Surfacing in Z is not a big problem however surfacing in X generates a
big question.
If I am facing an aluminium disk say 150mm diameter from out to in with
a carbide tool, I or the system can determine the initial rpm to start
the cut (based on surface speed and diameter) and then the system can
ramp up the speed as the tool moves further in, But what happens when
the max speed of the spindle is reached? Does it just carry on at that
speed? If so does that affect surface finish? Obviously the feed per rev
is not changing.
What is considered to be the main reason for wanting CSS when facing,
efficiency or surface finish.
Richard

#726

I'd say surface finish.  If you clamp a casting onto your face plate and run the tool across it you'll see various patterns as the SFM changes.  Take that same casting and use a fly cutter on your mill with a power feed and when you are on the 'sweet' spot the surface is beautiful.

I think when facing you get smooth cutting and then tearing etc.

Now, about spindle speeds.  My Unimat DB-200 is rated from 375  to  9200  RPM.  When turning tiny watch parts or other intricate mechanisms those items almost always need to be turned at pretty high speeds even with HSS tooling.    Even the Sherline can go from 70-2800 and I think with appropriate pulleys even faster.

For example.

200 sfm for brass (say a clock or watch movement) and 0.125" diameter you need 6112 RPM.  Move up to 0.375 and the RPM drops to 2037.  And apparently if you use carbide speeds can be up to 4x faster.

I don't think anyone will use a 14" lathe to turn large numbers of 0.125" parts but that last 0.375" diameter when facing does need to be as fast as possible.

John

Show quoted text

-----Original Message-----
From: [email protected] [mailto:[email protected]] On
Behalf Of Richard
Sent: February-25-20 11:07 PM
To: [email protected]
Subject: [digitalhobbyist] CSS questions #CSS

Constant Surface Speed has been mentioned a few times on this and other
groups. Whilst I am fully aware of what it is I am not aware of how it
is handled in the real world.
Surfacing in Z is not a big problem however surfacing in X generates a
big question.
If I am facing an aluminium disk say 150mm diameter from out to in with
a carbide tool, I or the system can determine the initial rpm to start
the cut (based on surface speed and diameter) and then the system can
ramp up the speed as the tool moves further in, But what happens when
the max speed of the spindle is reached? Does it just carry on at that
speed? If so does that affect surface finish? Obviously the feed per rev
is not changing.
What is considered to be the main reason for wanting CSS when facing,
efficiency or surface finish.
Richard

#727

Richard with my Consew Brushless DC motor install on my lathe I will have (easy) programagic control over spindle speed. I "should" be able to implement CSS. I will l be using a DS1803 digital potentiometer?and Arduino Mega, actually I could use any micro processor or even a computer.?

I will "probably" (ha) need programming help.

So I (we) should be able to answer lots of questions concerning?CSS but I should also be able to vary the speed for threading and turning.?

I will also be measuring Amps on my motor so I could "theoretically" be programagically watching motor load.

The possibilities are really interesting .

Ralph?

Show quoted text

On Wed, Feb 26, 2020 at 2:07 AM Richard <edelec@...> wrote:

Constant Surface Speed has been mentioned a few times on this and other
groups. Whilst I am fully aware of what it is I am not aware of how it
is handled in the real world.
Surfacing in Z is not a big problem however surfacing in X generates a
big question.
If I am facing an aluminium disk say 150mm diameter from out to in with
a carbide tool, I or the system can determine the initial rpm to start
the cut (based on surface speed and diameter) and then the system can
ramp up the speed as the tool moves further in, But what happens when
the max speed of the spindle is reached? Does it just carry on at that
speed? If so does that affect surface finish? Obviously the feed per rev
is not changing.
What is considered to be the main reason for wanting CSS when facing,
efficiency or surface finish.
Richard

--
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

#728

John those are set spindle speeds, I think CSS is looking for variable speeds.

Ralph

Show quoted text

On Wed, Feb 26, 2020 at 2:56 AM John Dammeyer <johnd@...> wrote:

I'd say surface finish.? If you clamp a casting onto your face plate and run the tool across it you'll see various patterns as the SFM changes.? Take that same casting and use a fly cutter on your mill with a power feed and when you are on the 'sweet' spot the surface is beautiful.

I think when facing you get smooth cutting and then tearing etc.

Now, about spindle speeds.? My Unimat DB-200 is rated from 375? to? 9200? RPM.? When turning tiny watch parts or other intricate mechanisms those items almost always need to be turned at pretty high speeds even with HSS tooling.? ? Even the Sherline can go from 70-2800 and I think with appropriate pulleys even faster.

For example.

200 sfm for brass (say a clock or watch movement) and 0.125" diameter you need 6112 RPM.? Move up to 0.375 and the RPM drops to 2037.? And apparently if you use carbide speeds can be up to 4x faster.

I don't think anyone will use a 14" lathe to turn large numbers of 0.125" parts but that last 0.375" diameter when facing does need to be as fast as possible.

John

> -----Original Message-----
> From: [email protected] [mailto:[email protected]] On
> Behalf Of Richard
> Sent: February-25-20 11:07 PM
> To: [email protected]
> Subject: [digitalhobbyist] CSS questions #CSS
>
> Constant Surface Speed has been mentioned a few times on this and other
> groups. Whilst I am fully aware of what it is I am not aware of how it
> is handled in the real world.
> Surfacing in Z is not a big problem however surfacing in X generates a
> big question.
> If I am facing an aluminium disk say 150mm diameter from out to in with
> a carbide tool, I or the system can determine the initial rpm to start
> the cut (based on surface speed and diameter) and then the system can
> ramp up the speed as the tool moves further in, But what happens when
> the max speed of the spindle is reached? Does it just carry on at that
> speed? If so does that affect surface finish? Obviously the feed per rev
> is not changing.
> What is considered to be the main reason for wanting CSS when facing,
> efficiency or surface finish.
> Richard
>
>

--
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

#729

开云体育

I mentioned those as the range of speeds you get with small lathes.? My little Unimat will eventually lose that stupid like underpowered brushed sewing machine motor for one a bit larger with Manjeet's UHU servo driver board.? Photo attached.? That's a surplus printer motor good to 3600 RPM I think.? So I'd still want a couple of pulleys to perhaps get 7200 RPM at least.

?

With that I then would have 0 to 7200 RPM and there's enough torque drive.? The Unimat is so small that I believe size 17 stepper motors will work for both axis which means something like a BeagleBone cape meant for the 3D printing market would be more than adequate for driving this along with an encoder disk on the spindle.

?

At this point a keyboard, mouse and display that are all collectively larger than the lathe itself have always seemed a bit over kill so once again, a smaller LCD interface with lots of buttons on a panel not much larger than my ELS would be ideal.? But it would still involve somehow rewriting the AXIS user interface for MachineKit to deal with a smaller display and keyboard with commands that ultimately use the CNC engine of MachineKit to create ELS motion.

?

In the long run, whether it be for a dedicated small PC type motherboard and Ethernet MESA to parallel or the 32 bit TI processor on a custom board looking like a Beagle etc. the idea of a non-video screen and PC keyboard/mouse as a starting point is a project begging to be built.? That infrastructure then allows the buttons and the display plus an MPG knob to in essence be a custom pendant for LinucCNC but behave like an ELS.

?

And with that you'd easily be able to do CSS.

?

John

?

Show quoted text

From: [email protected] [mailto:[email protected]] On Behalf Of Ralph Hulslander
Sent: February-26-20 8:03 AM
To: [email protected]
Subject: Re: [digitalhobbyist] CSS questions #CSS

?

John those are set spindle speeds, I think CSS is looking for variable speeds.

?

Ralph

?

On Wed, Feb 26, 2020 at 2:56 AM John Dammeyer <johnd@...> wrote:

I'd say surface finish.? If you clamp a casting onto your face plate and run the tool across it you'll see various patterns as the SFM changes.? Take that same casting and use a fly cutter on your mill with a power feed and when you are on the 'sweet' spot the surface is beautiful.

I think when facing you get smooth cutting and then tearing etc.

Now, about spindle speeds.? My Unimat DB-200 is rated from 375? to? 9200? RPM.? When turning tiny watch parts or other intricate mechanisms those items almost always need to be turned at pretty high speeds even with HSS tooling.? ? Even the Sherline can go from 70-2800 and I think with appropriate pulleys even faster.

For example.

200 sfm for brass (say a clock or watch movement) and 0.125" diameter you need 6112 RPM.? Move up to 0.375 and the RPM drops to 2037.? And apparently if you use carbide speeds can be up to 4x faster.

I don't think anyone will use a 14" lathe to turn large numbers of 0.125" parts but that last 0.375" diameter when facing does need to be as fast as possible.

John

> -----Original Message-----
> From: [email protected] [mailto:[email protected]] On
> Behalf Of Richard
> Sent: February-25-20 11:07 PM
> To: [email protected]
> Subject: [digitalhobbyist] CSS questions #CSS
>
> Constant Surface Speed has been mentioned a few times on this and other
> groups. Whilst I am fully aware of what it is I am not aware of how it
> is handled in the real world.
> Surfacing in Z is not a big problem however surfacing in X generates a
> big question.
> If I am facing an aluminium disk say 150mm diameter from out to in with
> a carbide tool, I or the system can determine the initial rpm to start
> the cut (based on surface speed and diameter) and then the system can
> ramp up the speed as the tool moves further in, But what happens when
> the max speed of the spindle is reached? Does it just carry on at that
> speed? If so does that affect surface finish? Obviously the feed per rev
> is not changing.
> What is considered to be the main reason for wanting CSS when facing,
> efficiency or surface finish.
> Richard
>
>

--
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

Test_UHU.jpg