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Author Topic: Stril Barents- a Multi role vessel  (Read 33356 times)

Capt Podge

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Re: Stril Barents- a Multi role vessel
« Reply #150 on: February 11, 2018, 02:26:22 PM »

Great to know you're going to carry on with this one, especially in view of the efforts to date, hope you get things sorted and get back on track - looking forward to it O0

Regards,

Ray.


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cos918

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Re: Stril Barents- a Multi role vessel
« Reply #151 on: February 11, 2018, 04:14:30 PM »

Hello Brian
glad to hear you are caring on . Have you though about using aircraft snakes so you can place the actuator some were serviceable.
If you are going for servos it is very easy to mod them for 180deg trow




John
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Brian60

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Re: Stril Barents- a Multi role vessel
« Reply #152 on: February 11, 2018, 05:29:19 PM »

cheers for the support guys.

John I could modify the servo's but using a arduino for the functions on the boat there really is no need. You can set it to park and begin its sweep at 0degrees (really about 4 or otherwise it jitters) and end anywhere up to 180 degrees ( again really about  176)

This few degrees less at each end of the travel I have found during testing is due to servo jitter. If it gets to 0 or 180 and slight play in the mechanism means it drops back slightly. The arduino doesn't know the cause, it just knows the servo is not at 0 or 180, so keeps sending the signal to get it there, causing the servo to jitter. By giving a couple of degrees at each end the problem is solved. Of course if you choose any increment between those figures to use, say 25 and 120 degrees, there is no problem at all, its just the end stops of the servo that messes up.

ballastanksian

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Re: Stril Barents- a Multi role vessel
« Reply #153 on: February 11, 2018, 09:47:51 PM »

Sometimes you just have to walk away from it for a month or a few weeks just to settle your frustration and let the little grey cells formulate a plan of action. That's why I reckon having an easy project as well as a long term one is good to swap between. It's not always cost effective but then neither is dumping hours of work and many pounds of materials especially as you have such a challenge getting some items.

Good on you Brian. I look forward to your updates as this is a lovely build and will look awesome when completed  :-))
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Tafelspitz

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Re: Stril Barents- a Multi role vessel
« Reply #154 on: February 12, 2018, 07:21:57 AM »

Bummer you had to rip her apart, but also glad that you decided to carry on. Would have been a pity to let it go.
One step after the other. Or as Kansas would say: "Carry on my wayward son, for there'll be peace when you are done" ok2
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Brian60

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Re: Stril Barents- a Multi role vessel
« Reply #155 on: February 12, 2018, 12:29:37 PM »

Kansas, now there's a blast from the past! always been a Skynyrd fan myself O0

Anyway I looked back at my last post and realised I never explained the servo thing simply. So here is a diagram. On the left your normal servo, you plug it in to the receiver port and it centres to 0, you move the stick on the Tx and it swings to 90 degrees either direction.

Now, if you take that servo and plug it into an arduino instead you get more control over it. The arduino sees the servo as a constant movement, no centre position (unless you want it to) It can begin at the 0 point and finish at 180 degrees, or start and finish at any chosen degree in between these figures. On startup, it does not go to the centre position as per the normal servo, no, it always begins at the point programmed into the arduino.

Hope that makes that point clearer!

cos918

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Re: Stril Barents- a Multi role vessel
« Reply #156 on: February 12, 2018, 06:25:27 PM »

Brian a normal servo only moves 90 deg total unless you mod it


John
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Brian60

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Re: Stril Barents- a Multi role vessel
« Reply #157 on: February 12, 2018, 06:55:52 PM »

Brian a normal servo only moves 90 deg total unless you mod it


John

Sorry John they don't, all servo's swing through an arc of 180 degrees in total - 90 degrees each side of centre or parked position. Here are 3 photos of a SG90 servo which is representative of all servo's. First shows it all the way to the left, 2nd is in the 'off or park' position which is where it centres when switched on by the receiver. The 3rd is all the way to the right. This corresponds with your stick position, centre is off, push to the left servo moves all the way to left, push right and similar.

All standard servo's move through a complete half circle, which is 180 degrees, some like sail servo's are continuous.

JimG

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Re: Stril Barents- a Multi role vessel
« Reply #158 on: February 12, 2018, 09:01:54 PM »

If you are getting 180 degree movement from a standard servo then you are sending it a signal outside of the normal 1000 to 2000 millsecond pulse rate. Just checked two servos with a servo tester and got around 100 degrees movement over this pulse range. I couldn't get 180 degrees as the tester only went from 900 to 2100 ms . You must be sending from below 500 and above 2500 ms pulses. The only way I can see to get 180 degree movement is to use a retract servo (unfortunately these tend not to be proportional but only go to their end points) or use a programmable digital servo where you can program the end points for greater movement.

Jim
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cos918

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Re: Stril Barents- a Multi role vessel
« Reply #159 on: February 12, 2018, 10:00:57 PM »

 Brian
buy an normal servo and plug it in to a RX and you get about 90 deg throw . Add two resistors to the wires coming from the edge of the pot say 1.8 to 2.6k and you will get about 170 deg . you may have to remove a mechanical stop.
You can get these devices that stretch the signal and sit in line on the servo lead but i have never seen them. You can buy a 180 deg servo .


John 
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Brian60

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Re: Stril Barents- a Multi role vessel
« Reply #160 on: February 13, 2018, 03:10:51 PM »

OK I've done some testing today.

Servo's as my photos above show have a full 180 degree travel left centre right. You can do this by moving it manually.
It also has 180 degrees of travel if plugged into one of my arduino's be that a Uno, a Mega or even a Nano.

Then I plugged it into my servo tester and got about 130 degrees give or take. hmmmm.
Then I plugged the same servo into my tx.rx set and got about 90 degrees, even bigger hmmm.

So I deduce that people are being ripped off, not by the servo manufacturers, but by the tx/rx manufacturers. Now it needs a more technical mind then mine to come along and explain why the pwm signal from a tx isn't long enough to give full movement of a servo :embarrassed:

JimG

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Re: Stril Barents- a Multi role vessel
« Reply #161 on: February 13, 2018, 11:04:46 PM »

The problem is that most people want a linear output for their controls. However the servo arm gives a rotary output.  When the servo is restricted to around 45 to 50 degrees either side of center then the output from the arm is near enough linear for most people. When you want more movement you will find that the output gets less and less linear until near the position of 85 to 90 degrees from the center the output  hardly moves, the control rod moves sideways instead.
So the reason the Tx manufacturers have them set up to only give around 100 or 90 degree total movement is that this suits the vast majority of needs. Normally only retract servo for aircraft undercarriages use 180 degrees and this is because the force on the servo arm at the end of the movement is through the center of the arm and the arm will not move under load. With a normal servo movement the force at the end of the arm can cause it to change position, not a good idea if the maximum movement is locking the wheels up or down.

Jim
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Brian60

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Re: Stril Barents- a Multi role vessel
« Reply #162 on: February 19, 2018, 10:53:16 AM »

OK lets get rid of some photo's from the last couple of weeks. First the construction before the destruction %%   The forward tunnel thrusters have been installed in the tubes.. These were made from abs plumbing pipe for the tubes as per the aft ones, the caps that hold the actual gearbox of the thruster were cut to shape out of a straight connector for the pipe, in other words its a sleeve for joining lengths of the pipe for plumbing purposes, I just cut a couple to form caps that could be bonded on with abs pipe cement.

The motors are brushless outrunners, the two brackets with be interconnected so that they don't turn when in operation, the bracket still has to be fabricated.

Brian60

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Re: Stril Barents- a Multi role vessel
« Reply #163 on: February 19, 2018, 10:56:25 AM »

Some more floodlights and 3 spotlights made by casting clear acrylic with 3mm leds inside of them. More lighting on the aft of the winchhouse etc, I was hoping to have all this part finished now, but the next sections will show why not.

Brian60

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Re: Stril Barents- a Multi role vessel
« Reply #164 on: February 19, 2018, 11:05:49 AM »

OK now the demoliton, first the bow, as I was having opening mooring doors in the bow, I also had to have an internal deck in case anyone decides to look inside, they would need to see the anchor winches, these were made from parts I cut on the laser machine. However it was all for nothing.

The doors I made in an earlier post, when mounted, the linkage to get them to open fouled on the anchor pockets inside the hull, there was no way to avoid this, no matter how many ways I redid the linkage it would not work. So it left me with the only option but to forget the doors, seal up the openings and put the piece of deck in the spares drawer.

On the other hand I did have success with making the lounge area, I put in seating and tables along with a wall mural :embarrassed: again just in case anyone decides to look through the large windows in the hull, this area has internal lighting as well. I now have 4 of these units made (different purposes) but they can't be bonded in until the hull paint is finished.

Brian60

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Re: Stril Barents- a Multi role vessel
« Reply #165 on: February 19, 2018, 11:13:55 AM »

OK the main demo, brought about by the stern doors not operating.

Once I got it ripped apart the reason for non operation became obvious. When I glued down the top deck with pva, as the deck bedded down the excess pva dripped onto the shafts of the stepper motors, stopping the travelling carrier from moving along its track. {:-{

So first what it looked like, then what it did look like after taking chisels to it. I had to chop my way through a lot of the support structure as well, so its quite a rebuilding excersize. The last photo here shows my solution. Out came the linear steppers and I made up two brass arms to fit onto servo's. Even so the space was limited to get into, so the servo's just got stuck to the hull bottom with a hotglue gun and then liberally coated with the stuff as well. Servo's were not my favoured option because the steppers have so much more control to offer, with regards closing. The servo's not so much even with my arduino.

Brian60

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Re: Stril Barents- a Multi role vessel
« Reply #166 on: February 19, 2018, 11:17:25 AM »

So now its rebuilding time for this section. I remade the internal deck the boom sits on. I mentioned previously it was not treadplate but a metal grid so that oil spillage falls through into a catch tank underneath. I have done this using fine mesh stainless grille.

Brian60

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Re: Stril Barents- a Multi role vessel
« Reply #167 on: February 19, 2018, 11:21:51 AM »

Lastly more demo. Remember these I made up for the deck that covers this section... Well with the new deck I am cutting and having further studied the photo's I had one side of it incorrect because it followed the cutout I had made to access the daughterboat hangar. So I have redone this section and still have access, but it means yes, these sections of cargo rail no longer fit and have to be remade.

So I'm making a short trip back to the UK, but at least on return I will be in a better position ie warmer here, to get the hull outside and once and for all get it sprayed in its main colours.

chipchase

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Re: Stril Barents- a Multi role vessel
« Reply #168 on: February 19, 2018, 11:45:58 AM »

Pleased your still carrying on with the build Brian, it will be worth it in the long run. I think we are all waiting for a bit warmer weather  :-))

Brian60

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Re: Stril Barents- a Multi role vessel
« Reply #169 on: March 17, 2018, 08:00:13 AM »

AND another in the saga of nothing going right with this build! Yesterday morning began to apply the top coat paint over the fresh primer, something I've done a dozen times before.

This is car primer and Humbrol enamel for the top coat, never have I seen a reaction like this ever! All I can think of is they have changed the formulation of the car primer over here. I might as well have attempted to spray water on it.

I left it and went to have a coffee and decide how best to clean it off. Going back 30 minutes later I didn't have to worry too much. Most of it as can be seen by the runs already forming, had run off the hull and pooled all over the floor, this was in our hobby room (4th bedroom) I sprayed inside because the wife is away and it was cold outside :D

So, with a roll of toilet tissue and a bottle of white spirit I began wiping it all off, 30 minutes later it was as clean as it was getting. Move it all out into the hallway and another 30 minutes and I had the floor clean as well, fortunately having ceramic tiling on all floors meant it was easy to remove. House now stinks of white spirit %% But I have a couple of weeks for it to dissipate before swimbo is back.

Off to our shopping mall now, only 40 miles away to buy some Vallejo acrylics, this was my last build with Humbrol as I had bought the paint months ago for this build. So at some point this next week expect a full new update with paint!!

Paul2407

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Re: Stril Barents- a Multi role vessel
« Reply #170 on: March 17, 2018, 08:13:17 AM »

Actually Brian I had the same reaction with car primer and humbrol enamel paints doing my Smit Rotterdam, like you I have to wipe it all off a quick light sanding and started again I had used a can of alloy wheel grey primer and can only assume itís like an etch primer and effected the enamel the second time I used Halfords red oxide doing the whole hull in this first the hand painted above the waterline in humbrol enamel and was fine even then sprayed over the whole lot with humbrol clear Matt varnish and that was also ok
So I can only assume that it was some kind of etch primer maybe something Stavros can confirm


Hope you sort it 👍
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Brian60

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Re: Stril Barents- a Multi role vessel
« Reply #171 on: March 17, 2018, 10:41:48 AM »

Yes still weird reaction, never seen the like before except for maybe tie die paint floating on water :embarrassed: I'm now back after the 80 mile jaunt, 40 there and back :(( its not fun living out in the sticks when you want something. Going to have a coffee then give it all a rub down with some 600 wet and dry before having a go with the Vallejo acrylics. The lower hull with red oxide is fine so its just a case of re-masking that  and making some new stencils for the various hull markings on the laser cutter. Full size spray gun now parked back in the tool room - I bought an adaptor for my new mini gun while I was out, so that will connect to my compressor airline, I wasn't fancying spraying this big a hull with an airbrush!

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Re: Stril Barents- a Multi role vessel
« Reply #172 on: March 17, 2018, 12:49:27 PM »

Keep my fingers crossed it all goes ok this time Brian  :-)) you mentioned somethin there too I've been meaning to by myself for some time an airbrush setup now just to choose one  :D

When your done lets have some pictures
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Umi_Ryuzuki

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Re: Stril Barents- a Multi role vessel
« Reply #173 on: March 17, 2018, 04:50:09 PM »

I would have thought it was mold release if you hadn't mentioned you laid down a coat of primer already.

 {:-{

Brian60

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Re: Stril Barents- a Multi role vessel
« Reply #174 on: March 17, 2018, 06:04:05 PM »

No its not that Umi. It's had several coats of primer since it came out of the mold, round about 5 off the top of my head, various rub downs between them in the last year. This afternoon it got a going over with a scotchbrite pad, then some wet dry 600 grit paper, then a wipe down with  a small amount of panel wipe. Sunday will tell whether I still get a reaction using acrylics rather than the Humbrol enamels.
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