Highly Flexible Cable

On 08/08/2020 02:02, Ricketty C wrote:
> We are going to need a highly flexible cable on this vent project if we mount a switch on the motor arm.  The arm swings through up to a 90 degree angle with most often a 60 degree angle.
> 
> I know there are special cords that provide for this sort of flexing.  They use cables to connect to printer heads in 3D printers and laser cutting devices.  What do they use.
> 

I'm guessing the switch is detecting a position rather than switching 
significant current.

So you don't /need/ copper. Steel will flex without fatiguing, think 
guitar string.

[I have several kilometres of four-core copper plated solid steel 
conductor wire, each conductor is enamel insulated and overall wrapped 
with waxed cotton.  It's very thin and was intended for use in 
wire-guided missiles, a totally mental idea.]

https://en.wikipedia.org/wiki/Swingfire

-- 
Cheers
Clive

lørdag den 8. august 2020 kl. 16.58.50 UTC+2 skrev Clive Arthur:
> On 08/08/2020 02:02, Ricketty C wrote:
> > We are going to need a highly flexible cable on this vent project if we mount a switch on the motor arm.  The arm swings through up to a 90 degree angle with most often a 60 degree angle.
> > 
> > I know there are special cords that provide for this sort of flexing.  They use cables to connect to printer heads in 3D printers and laser cutting devices.  What do they use.
> > 
> 
> I'm guessing the switch is detecting a position rather than switching 
> significant current.
> 
> So you don't /need/ copper. Steel will flex without fatiguing, think 
> guitar string.
> 

I believe some headphone cables are also steel for the same reason

"Ricketty C"  wrote in message 
news:9953c06c-d32a-4e6c-ac1a-ac93188de7a1o@googlegroups.com...
>
>On Saturday, August 8, 2020 at 6:55:24 AM UTC-4, Tim Williams wrote:
>> Right, flat flex cables are nice, for simple in-plane bending motion like
>> you get in a linear axis.  If more current (or better signal quality?) or
>> more complicated motion is required, or just more signals in a smaller 
>> cross
>> section, go with multiconductor cable, high strand count, neoprene 
>> jacket.
>
>What is special about neoprene?
>
>I figured there would be someone selling cable specifically intended for 
>this sort of use.  I wasn't able to find anything with any particular 
>specifications.
>
>This use only requires the cable to bend around a single axis.  No torsion 
>is required.  We have a pretty fair length to work in.  In fact, the motor 
>is on the other side of the bag from the control board, so if we use a flex 
>cable we likely would either need something two or three feet long to reach 
>or would need a local attachment point connected to the control board by a 
>separate cable.
>
>This is all about not wanting to add a $20 position encoder to sense the 
>specific position of the arm.  There are various failure modes that can be 
>detected by knowing when the arm is expected to contact the bag vs. when 
>air starts to flow (which we are sensing).  So either know where the arm is 
>via a position encoder, or put a contact sensor on the arm.
>
>I also drew up a simple diagram showing how contact with the bag could be 
>sensed via a "feeler" arm with a pivot point on the main arm translating 
>contact with the bag to a point at the center of rotation.  Then the switch 
>can be at a fixed position at the center of rotation without the flexible 
>cable.  But that seems to be a bit much to ask the mechanical engineer to 
>figure out.  Sounds to me like something fun to design.

Give https://www.mcmaster.com/flexible-cable a look.  They list several 
varieties of cable meant for continuous flexing.

-- 
Regards,
Carl Ijames 

On Saturday, August 8, 2020 at 9:23:28 AM UTC-4, Michael Kellett wrote:
> On 08/08/2020 02:02, Ricketty C wrote:
> > We are going to need a highly flexible cable on this vent project if we mount a switch on the motor arm.  The arm swings through up to a 90 degree angle with most often a 60 degree angle.
> > 
> > I know there are special cords that provide for this sort of flexing.  They use cables to connect to printer heads in 3D printers and laser cutting devices.  What do they use.
> > 
> In the days when we had phones with cords they used tinsel (copper tape 
> wound round cotton or other fibre).
> I couldn't find anyone (easily) just selling 2 or 4 core stuff on reels.
> 
> http://www.lk-tinsel-wire.com/
> 
> http://atagcables.co.uk/tinsel-wire.html
> 
> A long time ago we made military telephone handsets which used neoprene 
> sheathed tinsel curly cables - only necessary for wide temperature range 
> - I'm sure PVC will do you for ventilator temperature range.

I looked for phone curly cords but didn't find much in the off the shelf department.  Kinda obsolete these days I guess.  

I'm leaning toward a 12" or longer flat flex cable but that will require an interface board and other cable to reach the control board.  I think it would also require some sort of clamp so the stress isn't on the connectors.  PITA 

A wire cable is probably a better choice but finding one with a rated lifetime is the problem.  But it looks like we can use a continuous flex control cable and live rich, full lives. 

-- 

  Rick C.

  -- Get 1,000 miles of free Supercharging
  -- Tesla referral code - https://ts.la/richard11209

On Saturday, August 8, 2020 at 12:25:04 PM UTC-4, Carl wrote:
> "Ricketty C"  wrote in message 
> news:9953c06c-d32a-4e6c-ac1a-ac93188de7a1o@googlegroups.com...
> >
> >On Saturday, August 8, 2020 at 6:55:24 AM UTC-4, Tim Williams wrote:
> >> Right, flat flex cables are nice, for simple in-plane bending motion like
> >> you get in a linear axis.  If more current (or better signal quality?) or
> >> more complicated motion is required, or just more signals in a smaller 
> >> cross
> >> section, go with multiconductor cable, high strand count, neoprene 
> >> jacket.
> >
> >What is special about neoprene?
> >
> >I figured there would be someone selling cable specifically intended for 
> >this sort of use.  I wasn't able to find anything with any particular 
> >specifications.
> >
> >This use only requires the cable to bend around a single axis.  No torsion 
> >is required.  We have a pretty fair length to work in.  In fact, the motor 
> >is on the other side of the bag from the control board, so if we use a flex 
> >cable we likely would either need something two or three feet long to reach 
> >or would need a local attachment point connected to the control board by a 
> >separate cable.
> >
> >This is all about not wanting to add a $20 position encoder to sense the 
> >specific position of the arm.  There are various failure modes that can be 
> >detected by knowing when the arm is expected to contact the bag vs. when 
> >air starts to flow (which we are sensing).  So either know where the arm is 
> >via a position encoder, or put a contact sensor on the arm.
> >
> >I also drew up a simple diagram showing how contact with the bag could be 
> >sensed via a "feeler" arm with a pivot point on the main arm translating 
> >contact with the bag to a point at the center of rotation.  Then the switch 
> >can be at a fixed position at the center of rotation without the flexible 
> >cable.  But that seems to be a bit much to ask the mechanical engineer to 
> >figure out.  Sounds to me like something fun to design.
> 
> Give https://www.mcmaster.com/flexible-cable a look.  They list several 
> varieties of cable meant for continuous flexing.

Thanks.  I think the problem is this is a well established matter and you need to have particular knowledge of what works and what doesn't.  I don't see any guides anywhere on specifics of this sort of design.  The data I find on the cables is a bit shy of the info needed to know what will work and what won't. 

Heck, the listing in McMaster seems to be a single company and doesn't even say what the stranding is in the conductors. 

-- 

  Rick C.

  -+ Get 1,000 miles of free Supercharging
  -+ Tesla referral code - https://ts.la/richard11209

On Saturday, August 8, 2020 at 1:02:09 AM UTC, Ricketty C wrote:
> We are going to need a highly flexible cable on this vent project if we mount a switch on the motor arm.  The arm swings through up to a 90 degree angle with most often a 60 degree angle.  
> 
> I know there are special cords that provide for this sort of flexing.  They use cables to connect to printer heads in 3D printers and laser cutting devices.  What do they use. 
> 
> -- 
> 
>   Rick C.
> 
>   - Get 1,000 miles of free Supercharging
>   - Tesla referral code - https://ts.la/richard11209

Well, yes. You everyday inkjet printer has a long ribbon cable leading from
the main board to the print head. 
For example:
https://www.ebay.com/itm/Epson-WorkForce-Pro-WF-4734-Printer-Replacement-Print-Head-Ribbon-Cable/202811366906

A key issue besides the basic electrical and mechanical ones is "bend radius". The design, during motion, should keep the cable from making ny tight bends.
The ribbon cable maker, I expect, would specify this radius.

Cheers, Rich S.

  

On Saturday, August 8, 2020 at 1:02:09 AM UTC, Ricketty C wrote:
> We are going to need a highly flexible cable on this vent project if we mount a switch on the motor arm.  The arm swings through up to a 90 degree angle with most often a 60 degree angle.  
> 
> I know there are special cords that provide for this sort of flexing.  They use cables to connect to printer heads in 3D printers and laser cutting devices.  What do they use. 
> 
> -- 
> 
>   Rick C.
> 
>   - Get 1,000 miles of free Supercharging
>   - Tesla referral code - https://ts.la/richard11209

Well, yes. Your everyday inkjet printer has a long ribbon cable leading from
the main board to the print head.
For example:
https://www.ebay.com/itm/Epson-WorkForce-Pro-WF-4734-Printer-Replacement-Print-Head-Ribbon-Cable/202811366906

A key issue besides the basic electrical and mechanical ones is "bend radius". The design, during motion, should keep the cable from making any "tight" bends.
The ribbon cable maker, I expect, would specify this radius. In the inkjets
I've seen, the ribbon cable is not held down so the flexing can occur over
a long portion of it length - which I suppose, evens out the stresses.

Cheers, Rich S.

On Saturday, August 8, 2020 at 1:02:09 AM UTC, Ricketty C wrote:
> We are going to need a highly flexible cable on this vent project if we mount a switch on the motor arm.  The arm swings through up to a 90 degree angle with most often a 60 degree angle.  
> 
> I know there are special cords that provide for this sort of flexing.  They use cables to connect to printer heads in 3D printers and laser cutting devices.  What do they use. 
> 
> -- 
> 
>   Rick C.
> 
>   - Get 1,000 miles of free Supercharging
>   - Tesla referral code - https://ts.la/richard11209

Well, yes. You everyday inkjet printer has a long ribbon cable leading from
the main board to the print head.

For example:
https://www.ebay.com/itm/Epson-WorkForce-Pro-WF-4734-Printer-Replacement-Print-Head-Ribbon-Cable/202811366906

It might be worth a look inside any inkjet model, just to get the idea.

A key issue besides the basic electrical and mechanical ones is "bend radius".

The design, during motion, should keep the cable from making any tight bends.
The ribbon cable maker, I expect, would specify this radius. 

In the inkjets that I've worked with, the majority of the ribbon cable is not 
secured -- it flexes over much of its length, so the radius stays large enough,
so the stresses are minized and get spread out. 

Cheers, Rich S.

lørdag den 8. august 2020 kl. 21.07.24 UTC+2 skrev Rich S:
> On Saturday, August 8, 2020 at 1:02:09 AM UTC, Ricketty C wrote:
> > We are going to need a highly flexible cable on this vent project if we mount a switch on the motor arm.  The arm swings through up to a 90 degree angle with most often a 60 degree angle.  
> > 
> > I know there are special cords that provide for this sort of flexing.  They use cables to connect to printer heads in 3D printers and laser cutting devices.  What do they use. 
> > 
> > -- 
> > 
> >   Rick C.
> > 
> >   - Get 1,000 miles of free Supercharging
> >   - Tesla referral code - https://ts.la/richard11209
> 
> Well, yes. Your everyday inkjet printer has a long ribbon cable leading from
> the main board to the print head.
> For example:
> https://www.ebay.com/itm/Epson-WorkForce-Pro-WF-4734-Printer-Replacement-Print-Head-Ribbon-Cable/202811366906
> 
> A key issue besides the basic electrical and mechanical ones is "bend radius". The design, during motion, should keep the cable from making any "tight" bends.
> The ribbon cable maker, I expect, would specify this radius. In the inkjets
> I've seen, the ribbon cable is not held down so the flexing can occur over
> a long portion of it length - which I suppose, evens out the stresses.
> 
> Cheers, Rich S.

that's a FFC, https://en.wikipedia.org/wiki/Flexible_flat_cable

not a ribbon cable, https://en.wikipedia.org/wiki/Ribbon_cable

I believe one of the 3D printers used a ribbon cable and it didn't last very long

On Saturday, August 8, 2020 at 7:15:50 PM UTC, Lasse Langwadt Christensen wrote:
> lørdag den 8. august 2020 kl. 21.07.24 UTC+2 skrev Rich S:
> > On Saturday, August 8, 2020 at 1:02:09 AM UTC, Ricketty C wrote:
> > > We are going to need a highly flexible cable on this vent project if we mount a switch on the motor arm.  The arm swings through up to a 90 degree angle with most often a 60 degree angle.  
> > > 
> > > I know there are special cords that provide for this sort of flexing.  They use cables to connect to printer heads in 3D printers and laser cutting devices.  What do they use. 
> > > 
> > > -- 
> > > 
> > >   Rick C.
> > > 
> > >   - Get 1,000 miles of free Supercharging
> > >   - Tesla referral code - https://ts.la/richard11209
> > 
> > Well, yes. Your everyday inkjet printer has a long ribbon cable leading from
> > the main board to the print head.
> > For example:
> > https://www.ebay.com/itm/Epson-WorkForce-Pro-WF-4734-Printer-Replacement-Print-Head-Ribbon-Cable/202811366906
> > 
> > A key issue besides the basic electrical and mechanical ones is "bend radius". The design, during motion, should keep the cable from making any "tight" bends.
> > The ribbon cable maker, I expect, would specify this radius. In the inkjets
> > I've seen, the ribbon cable is not held down so the flexing can occur over
> > a long portion of it length - which I suppose, evens out the stresses.
> > 
> > Cheers, Rich S.
> 
> that's a FFC, https://en.wikipedia.org/wiki/Flexible_flat_cable
> 
> not a ribbon cable, https://en.wikipedia.org/wiki/Ribbon_cable
> 
> I believe one of the 3D printers used a ribbon cable and it didn't last very long

Indeed! Thank you, Lasse.