Re: [Emc-users] Maybe a minimally printed harmonic drive?

[Sam Sokolik]

https://www.youtube.com/watch?v=ZVVffljc7kE

On Tue, Feb 2, 2021 at 9:46 AM Gene Heskett  wrote:

> On Tuesday 02 February 2021 08:30:56 Sam Sokolik wrote:
>
> > I have looked at cycloidal drives and feel that they have too many
> > parts :)
> >
> > Gene
> > https://www.youtube.com/watch?v=Gx263nnTrqY
> >
> > Ran for over 6 hours like that - about 850rpm input.
> >
> I am highly impressed.
>
> Now finish the housing, and hang a load on it, like the worm of a BS-1
> while making another worm to replace the crappy worm in the Chinese
> BS-1. That worm is doomed to a higher wear rate, a fact I'm becoming
> aware of as I exercise this BS-1 servo for tuning.
>
> That is why I bought the ender3, but I was using O.P's code which was
> crappy code IMO. Turns out the ender3 can make stuff a heck of a lot
> better that the code I could DL from thingiverse. I now have the
> extruder motor on the x carriage, moving a modified stock hot end, and
> while its slower than some because the heating is only once the filament
> is in the nozzle, dozens of times more dependable than the stock setup.
> No clogging from cold filament because the hot stuff backs up into the
> heat sink and freezes.
>
> I think this loose ring idea has the most promise of making a long
> lasting drive, and shorter axially than any design so far. Please
> continue.
>
> Thank you Sam S.
>
> > On Thu, Jan 28, 2021 at 3:13 AM andrew beck 
> >
> > wrote:
> > > Guys just to chime in here.
> > >
> > > Sam went don't you design a cycloidal drive instead.  They are easy
> > > to make on a normal 3 axis Cnc mill with a end mill and much more
> > > rigid than a harmonic drive.  As they are not so fragile.  I'm
> > > planning on making some on my VMC soon.I don't understand why
> > > use a harmonic drive.  (I actually have a big harmonic drive here
> > > from a robot. )
> > >
> > > On Thu, 28 Jan 2021, 18:53 Bari,  wrote:
> > > > On 1/27/21 10:55 AM, Sam Sokolik wrote:
> > > > > Nice being able to make things while I sleep..
> > > > >
> > > > > 2 outside side rings - one 202 teeth - one 200 teeth.
> > > > > Inside flex ring - 200 teeth.  Feels good - for what it is..
> > > > >
> > > > > http://electronicsam.com/images/greenmachine/IMG_20210127_104237
> > > > >.jpg
> > > > > http://electronicsam.com/images/greenmachine/IMG_20210127_104628
> > > > >.jpg
> > > > > http://electronicsam.com/images/greenmachine/IMG_20210127_104354
> > > > >.jpg
> > > >
> > > > Timing belts will take the flex
> > > >
> > > > https://www.youtube.com/watch?v=Y8ZELQdgBbU
> > > >
> > > > https://www.youtube.com/watch?v=2YC-0C8oPUo
> > > >
> > > >
> > > > Cycloid prototype under microscope
> > > >
> > > > https://www.youtube.com/watch?v=um5GMOBgz6s
> > > >
> > > >
> > > > Hybrid planetary/harmonic drive - check out how they made it flex
> > > >
> > > > https://www.youtube.com/watch?v=sdRGrTHq4hA
> > > >
> > > >
> > > >
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>
> 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: 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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