Where to get gauge needles?

[twisted8]

Hello,
I want to make my own 767 flaps gauge and i was wondering if anybody had any ideas on how to make or where to buy the needle?

Thanks!

[No Longer Active]

I would just use 'clock needles' just search ebay or look in your junk shop, alternatively just buy cheap £1 travel clocks and use the needles.

Or-

Make your own using thin white plasticard (1mm thick), just draw out your very own shape and cut it out, to be honest its no more than a stretched and very long triangle with a rounded end....

I was given some simkits pointers to make my gauges and looking at them they are very easy to self reproduce....

Give it ago, work out the length required, shape it to the desired pointer shape and glue onto a little grommet or small cut of tube so that you can insert it over your servo...

Good luck!

[cscotthendry]

Another option fo DIY needles is the very thin and narrow strips of brass that K&S sell down at the hobby shops. It's fairly easy to shape the end to a point and drill a hole in it. Best of all, you can solder things to brass for the attachments.

[388TH_A]

And would i use a Stepper motor or a servo i know the differences between the two but as far as using it for a airspeed needle and flaps and so on i have no clue on witch one to use. do you guys know at all? O and thanks for the Cheaper needle buying ideas

[blueskydriver]

Not sure what your needles look like, but if you ad some close-up photos of the real gauges in this thread, I might have some Simkits needles that are extra you can have for free...

John

[phil744]

Dont forget that there are 2 needles in the gauge, one for left and one for right, if it was me i would buy a gauge of ebay and rip it tp pieces ;)

Photo attached

http://www.mycockpit.org/forums/attachment.php?attachmentid=2568&d=1260023198

[cscotthendry]

And would i use a Stepper motor or a servo i know the differences between the two but as far as using it for a airspeed needle and flaps and so on i have no clue on witch one to use. do you guys know at all? O and thanks for the Cheaper needle buying ideas

Use steppers where you want the pointer to go full circle and beyond. The drawback to steppers is that you have to have a home position sensor of some type.

A servo will usually only turn through about 180 degrees maximum. This can be increased with some kind of gearing between the servo shaft and the pointer shaft, but unless you modifiy the servo, their travel is limited internally.

[twisted8]

Thank you guys for all the suggestions and Phil for posting the picture! I didn't know it uses two needles but that seems really hard to build so I think I will stick to just one!



Not sure what your needles look like, but if you ad some close-up photos of the real gauges in this thread, I might have some Simkits needles that are extra you can have for free...
John
That'd be great, what a kind offer, I will send you a PM!

[cscotthendry]

Thank you guys for all the suggestions and Phil for posting the picture! I didn't know it uses two needles but that seems really hard to build so I think I will stick to just one!


Don't get put off by concentric pointers. You can do it easily with the little brass tubes that you buy in hobby stores. The sizes of those tubes are made so that each size fits nicely inside the next larger size. I have some concentric pointers in my engine gauges.
http://home.exetel.com.au/flightsim/Engine_Gauges.htm

[388TH_A]

Wow thanks for the link and answers i now have a better understanding on how to make a gauge. I have never really wanted to make one untill now. mostly because i was thinking that it would be REALLY hard to do. But looks really easy. Think i might tackle this sooner then i was thinking. And for this GREAT link in there per say better instructions to help me out. or where can i go to learn more about this? Also the Stepper motors i can go to the hobby store and get them. And then i wouldnt need and thing to big right? Just something Strong enough to move the gear for the needle. Vs trying to buy a really expensive one that is rated to move a RC something that weighs a lot. if that makes since. Pretty much i only need a stepper motor that is rated really small and it would work just fine for me then? that way if i get a small rated Motor it should cost less right? what kind of motors would you guys go with or doesn't matter?

[388TH_A]

O WOW i think there are Stepper motors in hold Floppy drives if that is the case does anybody know if there is and if i can use them?

[cscotthendry]

Here's the steppers I use and the link to the supplier. I use the PM20S which is quite small, and cheap. They are available from a number of other sources too.

http://www.futurlec.com.au/StepperMotors.jsp

Here's the US link for the same

http://www.futurlec.com/StepperMotors.shtml

These steppers come with a 64TPI pitch gear. They also have a connector, but I've not found a source for the other side of that connector.

If you don't already have a copy, Mike Powell's book on making simulated aircraft gauges got me started in this. I've not seen anything else like Mike's book for readability and coverage of the topic.

[388TH_A]

Well thanks and i did notice that your stuff it wired different then mine would be mostly because im using FSBUS. Do you know if it matters on what kind of Stepper motor i use with that? and thanks again for the links!

[388TH_A]

Wow the Stepper motors are really cheap. And ill just have to ask around and also see more of what im wanting to do so i can ask questions.

[twisted8]

Here's the steppers I use and the link to the supplier. I use the PM20S which is quite small, and cheap. They are available from a number of other sources too.

http://www.futurlec.com.au/StepperMotors.jsp

Here's the US link for the same

http://www.futurlec.com/StepperMotors.shtml

These steppers come with a 64TPI pitch gear. They also have a connector, but I've not found a source for the other side of that connector.


does the PM20S have enough resolution with only 20 steps? do you use additional gearing? I was under the impression I would need 1.8deg stepper motors.
I'm trying to build the flaps gauge and a wet compass
Thanks!

[388TH_A]

O geez with your comment now im not so sure on what im wanting to do and what to get lol

[No Longer Active]

I wouldnt bother with stepper motors.

I would purchase a Hi-Tec micro servo and gear it so that a 180 degree turn can provide a 270 degree+ movement.

[388TH_A]

O GEEZ now im even more confused lol

[twisted8]

I wouldnt bother with stepper motors.

I would purchase a Hi-Tec micro servo and gear it so that a 180 degree turn can provide a 270 degree+ movement.

Well problem is that a servo wouldn't work for a wet compass and I only have a the USB stepper card from opencokpits. Otherwise yeah it sounds like servos are easier to work with.

I see some gearing in this pic which makes more sense.
http://home.exetel.com.au/flightsim/myweb3/images/RMI_Wired1.jpg

is it better to use the gearing than use a 1.8deg stepper?

Thanks!

[No Longer Active]

In my experience of the first time I made some gauges, I didn't need gears as my fuel gauges needles turned less than 180 degrees which was the maximum that an un-modified servo can rotate.

If you was to use some very basic gears such as a gear that will convert a 180 degree movement into a 360 degree movement then you should be able to make your flaps gauge using SIOC coding.

As for stepper motors I know that it is a different story as you need to include some kind of interrupter additionally, which is why I prefer servo's as you d'ont need anything like that.

I dont know how to advise you on the compass rose as this is a particularly hard gauge to make, but it can be done by using servo motors and sensors (as my simkits compass rose is made this way).

I personally just prefer the whole servo aproach, indeed speppers are very durable and have excellent benefits but for the odd gauge then the servo on a servo card does the trick nicely!

[Mike.Powell]

Here's a nice little stepping motor I haven't seen used much by DIY instrument builders. It incorporates reduction gearing so you get relatively smooth movement from a very simple motor. It has an internal stop so you can't use this model in applications like compasses that require unrestricted rotation, but it does do away with the need for a shaft position sensor. To initialize the shaft position you simply step counterclockwise long enough to be sure the motor is against the stop.

These units are used in automotive gauges. I bought a couple through Ebay as replacement parts. Cheap$!
http://www.mycockpit.org/photopost/data/536/x25step.JPG

If you plan on using RC servos, you might not be aware of Servo City, a supplier of all sorts of useful servo-related items. In particular they sell gears that fit the end of RC servo output splines. http://www.servocity.com/html/gears___sprockets.html

If you're looking for information on how to build instruments, there are a few pages on my site that overview the topic.

http://www.mikesflightdeck.com/DIY_stepping_motors_instruments.htm
http://www.mikesflightdeck.com/DIY_servo_instruments.htm
http://www.mikesflightdeck.com/diy_aircore_instruments.htm

[cscotthendry]

does the PM20S have enough resolution with only 20 steps? do you use additional gearing? I was under the impression I would need 1.8deg stepper motors.
I'm trying to build the flaps gauge and a wet compass
Thanks!

Yes, the PM20S is pretty low res, but you can overcome this by a)Half stepping (See Mike's book about that) and b)Single reduction or compound gearing (Again, see the altimeter project in Mike's book, or my altimeter)

Servos are good where the gauge doesn't have to go full circle. They can be made to go full circle by removing the internal stop, but then you're back to needing a home position sensor of some kind and no better off than using steppers. I prefer to use steppers where possible as the signals that drive them don't require as much critical timing code to run them as do servos. However, if you're using a ready-made solution such as an open-cockpits, phidgets, or similar driver board, then you don't have to worry about it.

For your compass, I'd use a stepper. For the flaps gauge, I'd use a servo or those steppers that Mike posted pics of.

Mike: Do you have a source for those steppers that can supply them on demand?

[Mike.Powell]

Mike: Do you have a source for those steppers that can supply them on demand?

There are at least two vendors on Ebay supplying those stepping motor movements: "digital_dash_solutions" and "mandigital". See Ebay items 220495246141 and 230409622645 for examples. I can't remember who I bought from, but these vendors appear representative.

[cscotthendry]

There are at least two vendors on Ebay supplying those stepping motor movements: "digital_dash_solutions" and "mandigital". See Ebay items 220495246141 and 230409622645 for examples. I can't remember who I bought from, but these vendors appear representative.

Those look pretty neat. I have a few questions that the eBay sellers don't mention:

What diameter is the output shaft?
How far does the output shaft turn end to end?
How many steps does it take end to end?
Are they unipolar or bipolar?
Are they 12V or 5V?

Thanks

[Mike.Powell]

Here's a link to the manufacturer's product information page. You can download a spec sheet from it. http://www.switec.ch/products/switec/switec.html

[cscotthendry]

Thanks. It's a Swatch!