Model Boat Mayhem

Please login or register.

Login with username, password and session length.
Pages: [1]   Go Down

Author Topic: how to make a working gun turret  (Read 257 times)

frogman3

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 1,141
  • Model Boat Mayhem is Great!
  • Location: norfolk england
how to make a working gun turret
« on: April 14, 2021, 09:00:38 am »

HI ALL well im thinking of tryin to make my guns turrets on my tiger travis left an right an the guns elevate up an down ive got a few vague ideas but i wonder if anyone has done on on here to help me get a start in how to go about this as i was just goin to have a servo push the turret  left an right but im not happy with that idea be much better with a motor turning the turrest but i need info so any ideas an diograms ?
cheers all
chris  :-))
Logged

HMS Invisible

  • MICROGYROS.COM
  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 341
  • Location: Paisley, Renfrewshire
    • Yes, it works!
Re: how to make a working gun turret
« Reply #1 on: April 14, 2021, 09:51:56 am »

Reverse engineering a low spec servo isn't always the best start but it's where info and diagrams and demos could help. I often come across reply posts on why this'n'that won't work from folk who don't know how electronic rc gear, like a basic servo, works at the component level.

 I've taken a standard, quarter turn Futaba servo to slow it down, increase the travel beyond 180 degrees, reduce and increase deadband and so on. I can tell you this doesn't work well because the deadband, hence controllable resolution, is ten times that of its quarter turn equivalent. Geoff's observations would be shared by anyone who uses the same servo out of the box.  The 2 turn servo will work perfectly well as a budget price, low spec sailwinch but is worse than a quarter turn servo to reverse engineer into a turret mechanism.

 
... i was just goin to have a servo push the turret  left an right but im not happy with that idea be much better with a motor turning the turrest but i need info so any ideas an diograms ?
So what's the specific problem that makes you unhappy with the idea?
Each way comes with its pros and its cons.
Logged
< All manner of contact methods over to the left.

frogman3

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 1,141
  • Model Boat Mayhem is Great!
  • Location: norfolk england
Re: how to make a working gun turret
« Reply #2 on: April 14, 2021, 12:26:41 pm »

Reverse engineering a low spec servo isn't always the best start but it's where info and diagrams and demos could help. I often come across reply posts on why this'n'that won't work from folk who don't know how electronic rc gear, like a basic servo, works at the component level.

 I've taken a standard, quarter turn Futaba servo to slow it down, increase the travel beyond 180 degrees, reduce and increase deadband and so on. I can tell you this doesn't work well because the deadband, hence controllable resolution, is ten times that of its quarter turn equivalent. Geoff's observations would be shared by anyone who uses the same servo out of the box.  The 2 turn servo will work perfectly well as a budget price, low spec sailwinch but is worse than a quarter turn servo to reverse engineer into a turret mechanism.

 So what's the specific problem that makes you unhappy with the idea?
Each way comes with its pros and its cons.


HI WELL as im building a fair sized ship i thought id like to  the turret turn by a motor an i have been lookin at big ring gears on the web but just wondered if anybody has done a turret by motors thats all for some help
chris
Logged

John W E

  • I see no ships !!
  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 8,601
  • Location: South shields
Logged

HMS Invisible

  • MICROGYROS.COM
  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 341
  • Location: Paisley, Renfrewshire
    • Yes, it works!
Re: how to make a working gun turret
« Reply #4 on: April 14, 2021, 01:17:44 pm »


HI WELL as im building a fair sized ship i thought id like to  the turret turn by a motor an i have been lookin at big ring gears on the web but just wondered if anybody has done a turret by motors thats all for some help
chris
The reduction ratio of a typical servo at 60 degree rotation per second, is around 300:1 and a shaft torque of about 2 kgcm.
You don't need further gear reduction if you lower the voltage and modify a few components.
Whatever you build, those figures are a guide to the total gear ratio, which might use a worm gear, and to the size of motor needed for turret rotation.

Here is an informative article on servo modification, if only to convert to continuous rotation. Link It would still benefit from lowering the power and altering a deadband resistor which would reduce overshoot and make it work better in conjunction with a servo slower.
Logged
< All manner of contact methods over to the left.

John W E

  • I see no ships !!
  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 8,601
  • Location: South shields
Re: how to make a working gun turret
« Reply #5 on: April 14, 2021, 01:36:19 pm »

hi there


I forgot to mention - I used several servo expanders and they also slow down the movement of the gun turret - to operate the rotation.   I used the original units produced by Forge Electronics and I note they have a new version available.   What this version is like compared to the 'old' one I am not sure.   However, I know that the version I have does the job really well  -  it slows the movement of the turret down from left to right and gives you 180 degrees.    I also have another servo fitted in the turret itself which operates the turret elevation.  This has another unit which slows down the movement of the gun barrels to give a more realistic affect.  The servo for the rotation of the turret is mounted under the deck - there is also a servo under the superstructure as well.

Here is a link to Forge.

Servo Controller (forge-electronics.co.uk)


john
Logged

frogman3

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 1,141
  • Model Boat Mayhem is Great!
  • Location: norfolk england
Re: how to make a working gun turret
« Reply #6 on: April 14, 2021, 01:58:29 pm »

Hi this may help you out


https://www.modelboatmayhem.co.uk/forum/index.php/topic,33734.msg402159.html#msg402159


john


HI John many thanks an is it possible for some pics of the turret turning mech under the decks ? an may  i download your turret pics for me to study ? cheers
chris
Logged

frogman3

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 1,141
  • Model Boat Mayhem is Great!
  • Location: norfolk england
Re: how to make a working gun turret
« Reply #7 on: April 14, 2021, 01:59:41 pm »

The reduction ratio of a typical servo at 60 degree rotation per second, is around 300:1 and a shaft torque of about 2 kgcm.
You don't need further gear reduction if you lower the voltage and modify a few components.
Whatever you build, those figures are a guide to the total gear ratio, which might use a worm gear, and to the size of motor needed for turret rotation.

Here is an informative article on servo modification, if only to convert to continuous rotation. Link It would still benefit from lowering the power and altering a deadband resistor which would reduce overshoot and make it work better in conjunction with a servo slower.
AN CHEERS for your help thank you
chris
Logged

John W E

  • I see no ships !!
  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 8,601
  • Location: South shields
Re: how to make a working gun turret
« Reply #8 on: April 14, 2021, 03:36:33 pm »

hi there,


The white drum thing is an actual mounting ring - which is made from Plasticard - and that is glue to the servo - and the ring is glued to the underneath the deck and in this photograph you can see the actual superstructure part.   Inside the drum there is a connection between the splines on the servo and the bottom of the turret, which is a tube that can be adjusted for various heights.
Logged

frogman3

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 1,141
  • Model Boat Mayhem is Great!
  • Location: norfolk england
Re: how to make a working gun turret
« Reply #9 on: April 14, 2021, 08:29:39 pm »

hi there,


The white drum thing is an actual mounting ring - which is made from Plasticard - and that is glue to the servo - and the ring is glued to the underneath the deck and in this photograph you can see the actual superstructure part.   Inside the drum there is a connection between the splines on the servo and the bottom of the turret, which is a tube that can be adjusted for various heights.


OH THANK YOU John for the pics an info cheers
chris
Logged

frogman3

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 1,141
  • Model Boat Mayhem is Great!
  • Location: norfolk england
Re: how to make a working gun turret
« Reply #10 on: April 15, 2021, 11:37:51 am »

HI again John well ive just looked right through your HMS EXESTER build an well one word from me AWESOME this build is an if my tiger turns out half as good i will be well pleased an ive been thinkin about the gun turrest build an i think i will have the gun barrells at a up preset angle an just have the turret travis
chris


Logged
Pages: [1]   Go Up