Any creative smart suggestions ?

[Externet]

Hi all.  Headache is possible.

Am after ways to attach a properly sized plastic disc like this

 on top of the flatty portion of a marine compass  dial :

And being capable of adjusting its bearing in respect of the compass bearing.

Yes, disasembling the compass, install it, and reassemble once.  The hard part is the added 360^o ruler disc (how is it called?) should be positionable from the outside.  As when the compass indicates a -say 50 degree heading- the added disc to indicate a chosen shift -say aiming  a 230^o heading-

Perhaps some perforation or method for halting the compass, and a knob? for the disc as way to turn the  (friction? mounted)  disc respect to it could be in your skills ?    It is likely a sealed dome,  filled with fluid.

 

Edited October 18, 2018 by Externet

[Sensei]

34 minutes ago, Externet said:

The hard part is the added 360^o ruler disc (how is it called?)

It's called "360^o protractor".

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

Quote

Any creative smart suggestions ?

Do you have (or access to) 3D printer.. ?

If you would print protractor-gear, it could be rotated by e.g. servo/stepper motor. It would be easier than cutting little teeths in existing protractor..

..or you could glue gear from Arduino sets, on the top, or the bottom of protractor.. and servo (with attached yet another gear) would be able to spin it.

https://www.ebay.com/itm/11-styles-Plastic-Gears-All-Module-0-5-Robot-Parts-for-DIY-Arduino/310703820390

Somebody with 3D printer could print new case for compass (if there is not enough space).

 

 

Edited October 18, 2018 by Sensei

[studiot]

 

Caution

Marine compasses are mounted on gimbal bearings, which although robust are very finely balanced.

Adding weights to this can easily unbalance the mechanism, leading to a systematic bias error in the compass.

[Externet]

13 hours ago, Sensei said:

Do you have (or access to) 3D printer.. ?

Thanks.  No, but I prefer to 2D print such protractor markings on a transparency film as for 'overhead' projectors. Cutting teeth is a good idea,  a manual setting/rotating knob is preferred.

What are these ?  Anyone knows ?

Edited October 18, 2018 by Externet

[DrP]

32 minutes ago, Externet said:

What are these ?  Anyone knows ?

They look like compasses.

14 hours ago, Externet said:

Am after ways to attach a properly sized plastic disc like this

 on top of the flatty portion of a marine compass  dial :

Sorry if this is a silly question - It looks as though there are already 360degrees of graduations on the compass dial - why do you need to add a protractor on top of it? What's wrong with the one on the compass dial? 

[Externet]

Thanks.  Nothing wrong with the markings on the compass dial, just need an extra shiftable disk on top, like on the last picture.  Perhaps I should look for a dry compass with openable cover, shift the added disc and close lid.

[studiot]

I would say the gadget on the guy's wrist is an orientiering compass.
You can see the gunsights for taking bearing of landmarks.

 

The small picture looks like a surveryors compass designed to be set level on a stand, jusging by the spirit level.

The foldable object at the back ege looks like it might be a magnifying scale reader.

 

Bearing in mind what I said about the gimbals, is it possible to achieve your objective with an extenal scale on a ring placed around the outside of the marine compass housing?

Edited October 18, 2018 by studiot

[Externet]

5 minutes ago, studiot said:

...is it possible to achieve your objective with an extenal scale on a ring placed around the outside of the marine compass housing?

It has to move with the compass dial as one piece, shifted in heading.

[studiot]

I thought this might be the case, but it was worth asking.

Can you therefore cement a magnetic disk dead centre on the top of the existing dial and another on the protractor and mount the protractor above the dial so that the magnets drag each other round?

 

[Externet]

Thanks. Adding magnetic material would destroy the compass ability to aim properly, if I understand you.

[studiot]

Not if its a perfect disk.

[tinkerer]

I interpret the OP title to be soliciting creative engineering ideas, of a general nature, rather than pertaining only to the one problem described. 

Thus, while designing and building my 1/8-scale live steam locomotive, I needed a very stout cylinder, preferably steel, about 8-inches in outside diameter, and about 4 feet long, from which to fabricate my boiler. Then the idea struck: commercial pressurized gas cylinder, wall thickness almost 1/4-inch, made of 4130 alloy steel, readily weldable, commonly used to ship and store gas at 3,000 psi (though, not hot) quite safely. Surely approximately 100 psi steam at ~ 500 `F should pose no problem, got the tank free, started work on the boiler!

Now, the problem: Being new and unsure of procedure here, my image being url generated does not embed, just sits there. So, i'll paste it but won't know the result until after submission. 

I see it worked! Anyone horrified by it?

 

Edited November 14, 2018 by tinkerer

[J.C.MacSwell]

On 11/13/2018 at 11:54 PM, tinkerer said:

I interpret the OP title to be soliciting creative engineering ideas, of a general nature, rather than pertaining only to the one problem described. 

Thus, while designing and building my 1/8-scale live steam locomotive, I needed a very stout cylinder, preferably steel, about 8-inches in outside diameter, and about 4 feet long, from which to fabricate my boiler. Then the idea struck: commercial pressurized gas cylinder, wall thickness almost 1/4-inch, made of 4130 alloy steel, readily weldable, commonly used to ship and store gas at 3,000 psi (though, not hot) quite safely. Surely approximately 100 psi steam at ~ 500 `F should pose no problem, got the tank free, started work on the boiler!

Now, the problem: Being new and unsure of procedure here, my image being url generated does not embed, just sits there. So, i'll paste it but won't know the result until after submission. 

I see it worked! Anyone horrified by it?

 

Only if it was full/pressurized before starting the cut...

[Frank]

1 hour ago, J.C.MacSwell said:

Only if it was full/pressurized before starting the cut...

Full of water would be best - no fumes.  A kid died using a plasma torch on a recycled empty drum despite it being rinsed out.

 

[J.C.MacSwell]

1 hour ago, Frank said:

Full of water would be best - no fumes.  A kid died using a plasma torch on a recycled empty drum despite it being rinsed out.

 

Very good point, but is that not an argon bottle?

[ALine]

can I get a picture of both the top and side views of the marine compass you want to be using along with a top and side view of the plastic disk thing?

 

[tinkerer]

On 12/3/2018 at 8:03 PM, J.C.MacSwell said:

Very good point, but is that not an argon bottle?

Nitrous Oxide, got it from a Dentist. I have heard all my life that liquid Propane is notorious for permeating tank "pores" (??), and cutting open a tank will likely cause an explosion. Can anyone verify that? 

Gasoline is notably nasty too. I once had to modify size of a steel gasoline tank, flushed it repeatedly with water, until hardly any smell remained at the fill neck, brought my torch flame near, and got an extremely loud "WHOOMP", which left me quite distraught, and the tank seriously bulged outwards on the sides!

[StringJunky]

2 minutes ago, tinkerer said:

Nitrous Oxide, got it from a Dentist. I have heard all my life that liquid Propane is notorious for permeating tank "pores" (??), and cutting open a tank will likely cause an explosion. Can anyone verify that? 

Gasoline is notably nasty too. I once had to modify size of a steel gasoline tank, flushed it repeatedly with water, until hardly any smell remained at the fill neck, brought my torch flame near, and got an extremely loud "WHOOMP", which left me quite distraught, and the tank seriously bulged outwards on the sides!

Probably best to warm the tank on the outside first to let the gas/petrol escape into the interior from the wall then blow it out with an airline for a minute or two. Petrol is not miscible with water and the trapped petrol in the wall pores will stay trapped.

[Frank]

On 12/3/2018 at 10:03 PM, J.C.MacSwell said:

Very good point, but is that not an argon bottle?

Your post reminded me of that tragedy and I thought it was important to mention, especially on an open forum.

 

14 hours ago, StringJunky said:

Probably best to warm the tank on the outside first to let the gas/petrol escape into the interior from the wall then blow it out with an airline for a minute or two. Petrol is not miscible with water and the trapped petrol in the wall pores will stay trapped.

How would you avoid heating above the auto-ignition point?  I'm thinking maybe not a blowtorch?  I've been wondering how to do this safely for a while.

[StringJunky]

25 minutes ago, Frank said:

Your post reminded me of that tragedy and I thought it was important to mention, especially on an open forum.

 

How would you avoid heating above the auto-ignition point?  I'm thinking maybe not a blowtorch?  I've been wondering how to do this safely for a while.

Boil water (or heat to a safe temperature if it needs to be lower than 100C)  and then stand the tank in it, with no ignition sources around...blow or vacuum vapours.  Or maybe water-cooled disc cutting. Another idea might be to stick a vacuum cleaner hose inside with the machine on whilst cutting.

Edited December 7, 2018 by StringJunky