Re: [Emc-users] Sheet metal operations.

[John Dammeyer]

> From: Roland Jollivet [mailto:roland.jolli...@gmail.com]
> To throw in my two cents;
> 
> I build a lot of prototypes, and get my parts laser cut, but a CNC turret
> punch would be a great have.
> 
> I've toyed with the idea a lot and came up with this strategy;
> - machine designed to up to 3mm sheet metal only, maybe half a full sheet
> (1.2 x 1.2m)
> - build a high speed nibbler rather than a turret punch
> - the machine has two fixed tools, a 2x2 square punch, and a 2mm round punch
> - high speed nibbling will allow almost any profile to be generated with
> these two tools
> - the machine would be a fixed gantry style, 2.4m wide, and the gantry beam
> is simply loaded up with extra mass to prevent oscillations
> 
> The mechanism would be hydraulically driven, with the pumps on the floor,
> and tubing up to the two cylinders
> The 'pump' is an eccentric piston, and free runs all the time, pushing and
> pulling oil into the tank. The volume is low
> When a punch operation is required, a pin will shoot into the oil line,
> redirecting the flow to one of the cylinders
> The pin will stay in position if continuous nibbling is required, or can be
> timed at intervals according to the sheet position
> (yes, you don't want to side load the tool too much)
> 
> While the explanation is laborious, I think it's a simple setup to make..
> 
> Roland

I think I understand that explanation.  However, for me the cost would be 
easily  $80K.  Why so much?  The cost of the bigger shop to fit something that 
large.
But I agree that only a few punch sizes are required.  

John



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[Emc-users] Sheet metal operations.

[Roland Jollivet]

To throw in my two cents;

I build a lot of prototypes, and get my parts laser cut, but a CNC turret
punch would be a great have.

I've toyed with the idea a lot and came up with this strategy;
- machine designed to up to 3mm sheet metal only, maybe half a full sheet
(1.2 x 1.2m)
- build a high speed nibbler rather than a turret punch
- the machine has two fixed tools, a 2x2 square punch, and a 2mm round punch
- high speed nibbling will allow almost any profile to be generated with
these two tools
- the machine would be a fixed gantry style, 2.4m wide, and the gantry beam
is simply loaded up with extra mass to prevent oscillations

The mechanism would be hydraulically driven, with the pumps on the floor,
and tubing up to the two cylinders
The 'pump' is an eccentric piston, and free runs all the time, pushing and
pulling oil into the tank. The volume is low
When a punch operation is required, a pin will shoot into the oil line,
redirecting the flow to one of the cylinders
The pin will stay in position if continuous nibbling is required, or can be
timed at intervals according to the sheet position
(yes, you don't want to side load the tool too much)

While the explanation is laborious, I think it's a simple setup to make..

Roland


On Tue, 2 Feb 2021 at 12:55, andy pugh  wrote:

> On Mon, 1 Feb 2021 at 21:49, John Dammeyer  wrote:
>
> > Anyway the plan was to at some time create an ELS controlled movable
> back fence for the 3:1 tool and an XY movement system for the Arbor press
> to give me limited punching capabilities like the attached picture.
>
> I have thought that this would be a good thing to have if I ever get
> round to making a CNC slotting head for my milling machine (Or if I
> find an OEM one for the mill at a reasonable price[1])
>
> Have you seen the Trumpf CNC punches? Fascinating machines:
> https://youtu.be/-xOR42xho9I
>
> I think that one limitation of such a device would be throat depth.
> The Trumpf machines have a huge one.
>
> There is probably value in mounting a linear rail to the bench in
> front of the arbor press and then mounting a couple of switchable
> magnets to the sliders just to manually move sheets in straight lines.
> (would probably work with think aluminium with a steel bar on top)
>
> Which reminds me of another fascinating sheet metal tool.
> https://youtu.be/OipSiPSRti8
> The inventor has, rather generously, written a web page on how to make
> your own.
> http://aaybee.com.au/Magnabend/Building%20Your%20Own%20Magnabend.html
> I have had a small amount of success improvising a similar arrangement
> with my mag-base drill.
>
> [1] Quite a fluid concept. The last time one came up it was £300 and
> far too expensive. If I saw one now at that price I would snap it up)
> --
> atp
> "A motorcycle is a bicycle with a pandemonium attachment and is
> designed for the especial use of mechanical geniuses, daredevils and
> lunatics."
> — George Fitch, Atlanta Constitution Newspaper, 1912
>
>
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Re: [Emc-users] Sheet metal operations.

[dave engvall]

hydraulics anyone?

Dave

On 2/4/21 12:57 AM, andy pugh wrote:

On Thu, 4 Feb 2021 at 08:31, John Dammeyer  wrote:


I watched a few of the Fellows gear shaper videos.  Gave me an idea.  I have an 
AC servo on the knee.  I've thought about adding motion to the quill but I do 
like the option for manual operation for some things.

But how about on the quill installing a 4 start 1 TPI ball screw.

I think that you would need a lot of servo torque to get enough axial
force, but it could be done.

Though I was thinking rather more in terms of a mechanical slotting
head, either modifying an existing one, or building from scratch.

I have an idea for a mechanical slotting head with mechanical stroke
control: https://youtu.be/NJUQAUyZrOg





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Re: [Emc-users] Sheet metal operations.

[andy pugh]

On Thu, 4 Feb 2021 at 08:31, John Dammeyer  wrote:

> I watched a few of the Fellows gear shaper videos.  Gave me an idea.  I have 
> an AC servo on the knee.  I've thought about adding motion to the quill but I 
> do like the option for manual operation for some things.
>
> But how about on the quill installing a 4 start 1 TPI ball screw.

I think that you would need a lot of servo torque to get enough axial
force, but it could be done.

Though I was thinking rather more in terms of a mechanical slotting
head, either modifying an existing one, or building from scratch.

I have an idea for a mechanical slotting head with mechanical stroke
control: https://youtu.be/NJUQAUyZrOg

-- 
atp
"A motorcycle is a bicycle with a pandemonium attachment and is
designed for the especial use of mechanical geniuses, daredevils and
lunatics."
— George Fitch, Atlanta Constitution Newspaper, 1912


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Re: [Emc-users] Sheet metal operations.

[John Dammeyer]

> From: andy pugh [mailto:bodge...@gmail.com]
> On Wed, 3 Feb 2021 at 03:28, John Dammeyer  wrote:
> 
> > > The idea would be to have a CNC controlled tool rotation combined with
> > > the conventional reciprocation.
> 
> > Is that what you mean?
> 
> No. The slotting tool will run up and down continuously on the spindle
> motor, as usual.
> But the tool will also have the ability to rotate on the C' axis.
> 
> Think in terms of a Fellows gear shaper.
> 
I watched a few of the Fellows gear shaper videos.  Gave me an idea.  I have an 
AC servo on the knee.  I've thought about adding motion to the quill but I do 
like the option for manual operation for some things.  

But how about on the quill installing a 4 start 1 TPI ball screw.  With an 
appropriate servo with a 1000 line encoder in quadrature there's still 0.00025" 
resolution.  But at the same time a fairly fast motion along with rotation on 
the C axis.  So a vertical shaper behaviour for something like keyways or for 
internal gear teeth.

Theoretically a lever on a pot could also be used as the feed handle for the 1 
TPI screw retaining the mechanical ability.  Probably need a switch on the 
quill clamping lever too.

John



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Re: [Emc-users] Sheet metal operations.

[andy pugh]

On Wed, 3 Feb 2021 at 03:28, John Dammeyer  wrote:

> > The idea would be to have a CNC controlled tool rotation combined with
> > the conventional reciprocation.

> Is that what you mean?

No. The slotting tool will run up and down continuously on the spindle
motor, as usual.
But the tool will also have the ability to rotate on the C' axis.

Think in terms of a Fellows gear shaper.

-- 
atp
"A motorcycle is a bicycle with a pandemonium attachment and is
designed for the especial use of mechanical geniuses, daredevils and
lunatics."
— George Fitch, Atlanta Constitution Newspaper, 1912


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Re: [Emc-users] Sheet metal operations.

[Gene Heskett]

On Tuesday 02 February 2021 22:24:16 John Dammeyer wrote:

> > From: andy pugh [mailto:bodge...@gmail.com]
> >
> > On Tue, 2 Feb 2021 at 17:22, John Dammeyer  
wrote:
> > > What's a CNC slotting head?
> >
> > It's like a slotting head, but CNC :-)
> >
> > The idea would be to have a CNC controlled tool rotation combined
> > with the conventional reciprocation.
> >
> > --
> > atp
>
> OK.  Let's see if I have that right.  My Spindle is driven (well will
> be as it's currently still  0V-10V) with step and direction.  There
> will be an index and of course encoder on the spindle.
>
> Once I have step/dir instead of PWM/DIR I should be able to tell the
> spindle where I'd like it to be.  So if I have a rectangular punch
> held and keyed in some repeatable fashion (better than the R8 pin)
> then I should be able to tell it to turn to 45 degrees and then move
> down.  (or knee move up).
>
> The motor holds the spindle pretty well solid.  In fact annoyingly so
> because unless I disable the AC servo it won't let me turn it.  I
> imagine though a brake is probably needed to ultimately hold it really
> stiff.
>
> Is that what you mean?
>
> But can you actually configure LinuxCNC to both run spindle as an RPM
> axis and also a positioning axis?  I realize the loop is closed for
> tapping but 60 teeth per rev for the encoder isn't the same as 3600
> for the nearest 10th of a degree.
>
> John

Correct John, you will need a higher ppr encoder. My spindle encoder is 
actually on the rear of the motor so it is subject to the backlash in 
the plastic gears, but its a 1000 ppr encoder whose "scale" is switched 
by tally switches on the shifter knob, from my ini file:

ENCODER_SCALE_H = 7161.61
ENCODER_SCALE_L = 14095.34

That is per revolution so I could get pretty close to a tenth in low, but 
the holding power within that tenth wouldn't be that great as its a ball 
bearing PMDC motor controlled by a pwmgen.

The BS-1 servo rests well within that tenth when stopped, but accuracy is 
subject to the backlash in the bs-1's worm and is quite slow getting 
there. Top speed with that PMDC 100 watt estate gate motor driving it is 
about 3 rpms. That driver motor has an encoder which checks out at 
666.667 counts/degree of the bs-1. For calibrating the scale I 
put a home switch on it and put some heat in the motor by measuring 100 
cycles of the rising edge of the home switch. As presently setup, it 
never quite gets to balance, friction stopping it an arcsecond or so 
early. The pwmgen driving a pair of BTS-7960's on a $6.40 driver is 
still outputting a very narrow pulse, well under 1% on time when it 
stops. I am not done piddling with the PID and the offset. I need to set 
its scale from the error direction, not the error itself. But other 
stuff has got in the way like losing the video on the 6040 about 18 
hours after I updated it to buster. 4 identical off lease dell's with i5 
cpu's & 4Gigs of dram s/b here tomorrow night. When I get done they will 
all be running from our buster image.

Stay safe and well everybody.

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page 


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Re: [Emc-users] Sheet metal operations.

[John Dammeyer]

> From: andy pugh [mailto:bodge...@gmail.com]
> On Tue, 2 Feb 2021 at 17:22, John Dammeyer  wrote:
> 
> > What's a CNC slotting head?
> 
> It's like a slotting head, but CNC :-)
> 
> The idea would be to have a CNC controlled tool rotation combined with
> the conventional reciprocation.
> 
> --
> atp

OK.  Let's see if I have that right.  My Spindle is driven (well will be as 
it's currently still  0V-10V) with step and direction.  There will be an index 
and of course encoder on the spindle.  

Once I have step/dir instead of PWM/DIR I should be able to tell the spindle 
where I'd like it to be.  So if I have a rectangular punch held and keyed in 
some repeatable fashion (better than the R8 pin) then I should be able to tell 
it to turn to 45 degrees and then move down.  (or knee move up).  

The motor holds the spindle pretty well solid.  In fact annoyingly so because 
unless I disable the AC servo it won't let me turn it.  I imagine though a 
brake is probably needed to ultimately hold it really stiff.

Is that what you mean?

But can you actually configure LinuxCNC to both run spindle as an RPM axis and 
also a positioning axis?  I realize the loop is closed for tapping but 60 teeth 
per rev for the encoder isn't the same as 3600 for the nearest 10th of a degree.

John






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Re: [Emc-users] Sheet metal operations.

[andy pugh]

On Tue, 2 Feb 2021 at 17:22, John Dammeyer  wrote:

> What's a CNC slotting head?

It's like a slotting head, but CNC :-)

The idea would be to have a CNC controlled tool rotation combined with
the conventional reciprocation.

-- 
atp
"A motorcycle is a bicycle with a pandemonium attachment and is
designed for the especial use of mechanical geniuses, daredevils and
lunatics."
— George Fitch, Atlanta Constitution Newspaper, 1912


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Re: [Emc-users] Sheet metal operations.

[John Dammeyer]

> From: andy pugh [mailto:bodge...@gmail.com]
> On Mon, 1 Feb 2021 at 21:49, John Dammeyer  wrote:
> 
> > Anyway the plan was to at some time create an ELS controlled movable back 
> > fence for the 3:1 tool and an XY movement system for
> the Arbor press to give me limited punching capabilities like the attached 
> picture.
> 
> I have thought that this would be a good thing to have if I ever get
> round to making a CNC slotting head for my milling machine (Or if I
> find an OEM one for the mill at a reasonable price[1])
> 
What's a CNC slotting head?

> Have you seen the Trumpf CNC punches? Fascinating machines:
> https://youtu.be/-xOR42xho9I
> 
Yes. I've seen similar machines in real life punching the back plate of my ELS 
kit.  Alas that company isn't there anymore.  

> I think that one limitation of such a device would be throat depth.
> The Trumpf machines have a huge one.

True.  The photo I attached was of a arbor press with a much deeper throat.  
The limitation ultimately is the size of the box foldable by either a box pan 
brake (say 12") or the 3:1 tool which in my case is 30" but they do come 
smaller.So punching half and then rotating the material by 180 degrees and 
punching the other half does effectively double the depth.

If it came down to needing something larger it could always be fabricated.

John




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Re: [Emc-users] Sheet metal operations.

[andy pugh]

On Tue, 2 Feb 2021 at 10:14,  wrote:

> http://www.metalsmith.co.uk/rivet-embossing-tool.htm

For real rivets I made:
http://bodgesoc.blogspot.com/2014/04/hydraulicrivetsqueezer.html

-- 
atp
"A motorcycle is a bicycle with a pandemonium attachment and is
designed for the especial use of mechanical geniuses, daredevils and
lunatics."
— George Fitch, Atlanta Constitution Newspaper, 1912


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Re: [Emc-users] Sheet metal operations.

[andy pugh]

On Mon, 1 Feb 2021 at 21:49, John Dammeyer  wrote:

> Anyway the plan was to at some time create an ELS controlled movable back 
> fence for the 3:1 tool and an XY movement system for the Arbor press to give 
> me limited punching capabilities like the attached picture.

I have thought that this would be a good thing to have if I ever get
round to making a CNC slotting head for my milling machine (Or if I
find an OEM one for the mill at a reasonable price[1])

Have you seen the Trumpf CNC punches? Fascinating machines:
https://youtu.be/-xOR42xho9I

I think that one limitation of such a device would be throat depth.
The Trumpf machines have a huge one.

There is probably value in mounting a linear rail to the bench in
front of the arbor press and then mounting a couple of switchable
magnets to the sliders just to manually move sheets in straight lines.
(would probably work with think aluminium with a steel bar on top)

Which reminds me of another fascinating sheet metal tool.
https://youtu.be/OipSiPSRti8
The inventor has, rather generously, written a web page on how to make your own.
http://aaybee.com.au/Magnabend/Building%20Your%20Own%20Magnabend.html
I have had a small amount of success improvising a similar arrangement
with my mag-base drill.

[1] Quite a fluid concept. The last time one came up it was £300 and
far too expensive. If I saw one now at that price I would snap it up)
-- 
atp
"A motorcycle is a bicycle with a pandemonium attachment and is
designed for the especial use of mechanical geniuses, daredevils and
lunatics."
— George Fitch, Atlanta Constitution Newspaper, 1912


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Re: [Emc-users] Sheet metal operations.

[marcus . bowman]

On 2021-02-01 21:47, John Dammeyer wrote:



What I'm wondering is if it's worth the trouble to add XY to a 3 ton
arbour press.  The back fence for the 3:1 tool is almost done so it's
just a matter of finishing it.  But I can't see how any of the CAD/CAM
software out there addresses using a small punch to nibble out a
larger hole.  And truthfully my JGRO based CNC router with a small end
mill can just as easily cut out metal plate.  Or for that matter the
mill.
But is an XY punch even worth the effort?


This is a project I, too, have had echoing around the inside of my head 
for a long time. I have a flypress and a small 2 ton arbour press.  One 
application I can see that could be significantly improved by adding an 
XY capability would be for pressing sheet metal to create dummy rivets, 
for scale model locomotives. That is not punching through, but punching 
to form a protrusion. There are some hand-operated machines for doing 
that, and they offers a guide to assist in manually slipping the metal 
into position.

http://www.metalsmith.co.uk/rivet-embossing-tool.htm
http://www.modelrailroading.nl/news%20articles/tools/pages/rivet%20press.htm
and the highly regarded, but no longer available, GW Models press which 
has some XY manual positioning adjustment:

https://picclick.co.uk/GW-Models-Universal-Rivet-Press-tool-173452688000.html
Personally, this seems to me like a job crying out for a decent CNC XY 
positioning system.
Add a controllable-depth Z axis capable of exerting modest pressure, and 
you would be able to enter lists of co-ordinates and press 
pre-determined patterns of rivets with ease.
Add a simple piercing punch and a bit more power and you would be able 
to punch the holes for actual rivets.
You could always try using a powered toggle press, as they are designed 
for this kind of task.Big and heavy, though.
A flypress might be a possibility, if you devised a mechanism for 
turning the shaft (easy) then pulling it (reverse rotation) smartly as 
though you were vigorously swinging the arm/handle. Moving the weight at 
speed produces the force.


Or create a jig for holding the sheet, and use a conventional CNC mill, 
with the addition of an arrangement for pressing or punching, and you 
would have the same thing. easy for thin brass, but not quite so 
straight forward where large forces are required on the Z axis.


Sounds like a useful project to me, whichever way you go.

Marcus


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[Emc-users] Sheet metal operations.

[John Dammeyer]

I've posted this under a new subject because Andy's EDM project had me looking 
through 25 year old copies of MEW and Home Shop Machinist etc.  Brought back 
memories of building the Gingery Hacksaw and Slip Roll so I could fabricate the 
propane fired foundry in order to be able to make the Gingery lathe.  Which I 
did and that spawned the Electronic Lead Screw project back in 2006.
 
The plan was to also make the shaper and mill but as luck would have it I ended 
up with a used metal bandsaw,  a 1942 vintage South Bend Heavy 10L with taper 
attachment and finally a House of Tools Mill (similar to the now discontinued 
G3616 from Grizzly).  I also purchased a 3 Ton Arbor press and a 30" 3:1 sheet 
metal tool along with a corner notcher.  My shop isn't large enough to fit a 
box pan brake or larger separate shear.
 
Anyway the plan was to at some time create an ELS controlled movable back fence 
for the 3:1 tool and an XY movement system for the Arbor press to give me 
limited punching capabilities like the attached picture.  
 
Now 14 years later I'm running out of ELS kits and still haven't built the back 
fence control and China dominates the cheap market with Encoders, Arduinos and 
stepper drivers.  Not to mention far less expensive linear rails and carriages. 
 
 
Given that I had a Pi4 with the MESA 7i92H running my mill for a while it seems 
like LinuxCNC may be a better choice for both the 3:1 back fence and XY 
positioning simply because it's an easy way to bring in the sequences.  One 
really only needs a few different size punches in square, triangle and round to 
be able to nibble out most holes in sheet metal thin enough for working with a 
3:1 tool.
 
But there's also a company nearby me that has a laser cutting system that can 
now operate lights out.  The sheets are picked, placed, punched and removed all 
automatically.  So for production it's not logical to do that sort of thing in 
house.  They also bend metal.
 
But, for that prototype or hobby, just like having a CNC Mill and Lathe, being 
able to bend and punch metal does come in handy.  Especially since I do more 
electronics than machining; at the moment.  The 3D printer now also finds a 
place that was there 25 years ago but done with other technologies.   Where 
before I'd bend up a box to hold an ESTOP switch now I 3D print switch holders 
and boxes for electronics.
 
What I'm wondering is if it's worth the trouble to add XY to a 3 ton arbour 
press.  The back fence for the 3:1 tool is almost done so it's just a matter of 
finishing it.  But I can't see how any of the CAD/CAM software out there 
addresses using a small punch to nibble out a larger hole.  And truthfully my 
JGRO based CNC router with a small end mill can just as easily cut out metal 
plate.  Or for that matter the mill.
 
The shearing, bending and rolling are still valid operations.  The press is 
still handing for pressing broaches through holes or bearings etc.  But is an 
XY punch even worth the effort?  So many of the projects from 1995 to about 
2005 in the magazines were pretty cool but from a time when some things just 
weren't available at low cost.  Now I think one would have to be nuts to try 
and build your own CNC mill from bar stock and rails.  
 
John Dammeyer
 
 
"ELS! Nothing else works as well for your Lathe"
Automation Artisans Inc.
www dot autoartisans dot com 
 
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