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Author Topic: Caldercraft Northlight Puffer with working Derrick Crane  (Read 84737 times)

Martin [Admin]

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Re: Caldercraft Northlight Puffer with working Derrick Crane
« Reply #150 on: February 27, 2010, 11:55:02 PM »

" surprised at the number reading but not asking questions."

   I, for one, am just sitting back in awe of Mike's audacity to even attempt such a feat!   :o
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Corposant

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Re: Caldercraft Northlight Puffer with working Derrick Crane
« Reply #151 on: February 28, 2010, 08:42:42 AM »

Peter

I feel I must apologise for my "lack of interest" remark. It was not meant to be a whinge - honest!

Many thanks for your previous help and for the tip about Aldi. Unfortunately their nearest store to us is 6 or 7 miles away from us but I'll keep my eyes peeled on their website.

Mike
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Re: Caldercraft Northlight Puffer with working Derrick Crane
« Reply #152 on: February 28, 2010, 08:55:50 AM »

Martin,

You have been busy! Your trawl net seems to have found my other "faux pas" too!!

"Audacity" - that's a good word! I hope my posts give encouragement to beginners like me.

I have to say that, without your forum and it's members, I would have given up!

Mike
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Re: Caldercraft Northlight Puffer with working Derrick Crane
« Reply #153 on: February 28, 2010, 09:06:35 AM »

Peter

I feel I must apologise for my "lack of interest" remark. It was not meant to be a whinge - honest!

Many thanks for your previous help and for the tip about Aldi. Unfortunately their nearest store to us is 6 or 7 miles away from us but I'll keep my eyes peeled on their website.

Mike
I cannot get out myself but I will ask my wife to pop in and ill send you a box if they have them, I buy the odd bit from them when they have offers they are not always the best you can get but the likes of the router cutters have got me out of a fix a few times with a odd shaped cutter that I will only say use once and a set of 12 is cheaper than one cutter from B+Q and does the job, same goes for some of the other tools.

Peter
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Martin [Admin]

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Re: Caldercraft Northlight Puffer with working Derrick Crane
« Reply #154 on: February 28, 2010, 09:10:08 AM »


Many thanks for your previous help and for the tip about Aldi. Unfortunately their nearest store to us is 6 or 7 miles away from us but I'll keep my eyes peeled on their website.

Mike

PM sent.
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Bradley

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Re: Caldercraft Northlight Puffer with working Derrick Crane
« Reply #155 on: February 28, 2010, 09:30:27 AM »

Mike,
You will find that if you go to Aldi's website you can get them to send you weekly emails about their special offers. :-))

Derek.
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Re: Caldercraft Northlight Puffer with working Derrick Crane
« Reply #156 on: February 28, 2010, 12:52:04 PM »

Peter,

Thanks again for your kind offer - and do give my kind regards to your wife. What would we do without them!

Martin,

Thanks too for your offer - I'm getting inundated!

Derek,

That's a good idea, I hadn't noticed that.

Many thanks,

Mike
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Re: Caldercraft Northlight Puffer with working Derrick Crane
« Reply #157 on: February 28, 2010, 02:09:15 PM »

would a boom made of brass rod help ? it would act more like the real thing and a spring may not be as important

Peter
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Re: Caldercraft Northlight Puffer with working Derrick Crane
« Reply #158 on: February 28, 2010, 02:45:12 PM »

Peter

I think the weight would be a problem with the boom swung over the side. See Bunkerbarge's warning of 07 October last year and his link http://www.albanyaerialphotos.com/stellamare.htm.

Martin claims to have contemplated a steel boom when making Jan's puffer!

The problem lies with the lines which are used to manipulate the boom in real life. I did contemplate using them for this purpose on the model but it was immediately apparent that this would be impractical - so they are purely decorative. It was your idea of using a pulley system, which worked brilliantly for the other "slack line", that prompted my efforts for the two lines in question.

Thanks for your continued interest,

Mike
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Re: Caldercraft Northlight Puffer with working Derrick Crane
« Reply #159 on: March 17, 2010, 05:00:45 PM »

Rather than adding even more temporary stuff to the mock-up, I resolved to start fitting everything into the hull before sorting out lateral boom movement....... but the seeds of doubt grew and grew in my mind: What if it doesn't work?

So, here's the next stage in the saga:

Some months ago, I painstakingly fitted a plastic gear to a servo in order to increase it's rotation:




only to discover, more recently, that FLJ sells a "servo stretcher"!

Before investing in the P96 and bearing in mind that driving the boom with the gooseneck pivot puts the servo at huge "mechanical disadvantage", I made up (out of an old piece of curtain rail) the direct drive linkage shown below.





The design allowed for it to slip if there was a jam but in practice the servo will simply stall, so I will be able to make it a lot neater.

The video shows the original plan in action.




Followed by the direct drive (as yet without P96).



(Note the ever decreasing length of the mast!)



The jerky boom movement, improved a bit with the direct drive, is not helped by the small knob on top of the Tx. I know, I'll fit a bigger one!

Is there anything else that needs testing before resuming work on the hull?
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Re: Caldercraft Northlight Puffer with working Derrick Crane
« Reply #160 on: March 20, 2010, 04:43:59 PM »

O bother (or something very similar), I've had an idea!

While my mind was re-visiting the boom lateral line tension problem, I thought let's try using one large pulley instead of several little ones - thus reducing the drag effect. So, did a quick calculation and reckoned that one of about 25mm diameter would take up the slack with 5 turns. With this attached to a small sheave of about 5mm diameter, tension would need to be applied over a distance of about 90mm - i.e. quite manageable.

So, I attacked a sheave from an old chart recorder with the lathe, lashed it onto the dreaded mock-up and the result is shown in the video:



The result showed such promise that the chap in the drawing office applied himself to the task with his usual efficiency:



I know what you're thinking - why on earth didn't he do that in the first place!

But then disaster struck. He thought, before I embark on this new idea, let's reconsider moving the boom by pulling it to and fro. (This approach had been rejected earlier on the basis of a quick experiment and anticipated problems when raising the boom - something that the yachting fraternity don't have to deal with!)

I have decided it could be possible. (The chap in the drawing office thinks so anyway.) The advantages are that the "mechanical disadvantage" of the servo would not apply and the system would not require such delicate control of the tension.

So, before I abandon several month's work on getting the boom to swing satisfactorily, I would greatly appreciate some advice.

Is there any reason why the lateral line bulwark attachment points should not be moved further for'ard - to about where the samson posts are sited? See plan:



A difficulty I can see is that I propose to site the shrouds further aft as I cannot believe that in real life the aft-most one would be in line with the mast.

Any suggestions warmly welcomed!

Mike
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Re: Caldercraft Northlight Puffer with working Derrick Crane
« Reply #161 on: April 26, 2010, 10:14:48 PM »

Am I chuffed or what!

In my last post, I was contemplating a radical change in moving the boom laterally. Driving it from the pivot point didn't seem mechanically sound. The aim was to pull it to and fro, as in real life. (As I mentioned, this had been unsuccessful many moons ago.)

Using a sail winch seemed the obvious approach.

First problem: They're expensive!
Second problem: They're much chunkier that a normal servo.
Third problem: It would need a pretty large diameter drum.
Solution: Make my own!

I had some plastic gears left over from my re-construction of the winch and the drum was turned up from a piece of acrylic sheet.



The intermediate gear and final pinion had brass sleeves inserted.
The spindles were soldered in using a wood block to get them vertical.





The result mounted in the mock-up:



The video shows the result:



It needs some refinement. The swing is not quite as far as I would like but FLJ's servo-stretcher should sort that. Since cutting off the bottom of the mast, the mock-up has become very wobbly but it has served it's purpose well and I now have a further incentive to start getting everything into the hull!

Mike
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Martin [Admin]

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Re: Caldercraft Northlight Puffer with working Derrick Crane
« Reply #162 on: April 27, 2010, 07:17:42 AM »

Most impressive!
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Roger in France

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Re: Caldercraft Northlight Puffer with working Derrick Crane
« Reply #163 on: April 27, 2010, 07:54:40 AM »

Wow!

Well done.

Roger in France
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Re: Caldercraft Northlight Puffer with working Derrick Crane
« Reply #164 on: April 27, 2010, 09:17:06 AM »

Thanks guys. I was particularly pleased that it worked with the lines (sheets?) going through the deck that far for'ard, which means an almost 90 deg swing is possible.

Mike
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Archibald H.

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Re: Caldercraft Northlight Puffer with working Derrick Crane
« Reply #165 on: April 27, 2010, 10:17:41 AM »

Brilliant model engineering, this is!

Cheerz, A!H.
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Re: Caldercraft Northlight Puffer with working Derrick Crane
« Reply #166 on: April 27, 2010, 11:04:14 AM »

Archibald,

Thanks for your kind comment. I don't think that "brilliant" is the right word though!

Mike
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Re: Caldercraft Northlight Puffer with working Derrick Crane
« Reply #167 on: April 27, 2010, 08:25:25 PM »


Nice piece of engineering. I'm going to say Brilliant as well. You deserve it.   O0

Ken


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Archibald H.

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Re: Caldercraft Northlight Puffer with working Derrick Crane
« Reply #168 on: April 27, 2010, 10:36:09 PM »

Nice piece of engineering. I'm going to say Brilliant as well. You deserve it.   O0
Ken

Hear, hear!
A!H
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Re: Caldercraft Northlight Puffer with working Derrick Crane
« Reply #169 on: April 27, 2010, 11:33:34 PM »

Thanks Ken. I've lost count of the number of superb models you've made since I started my attempt. I see that Bunkerbarge says "If you worry about how long it takes, you'd go crazy." - so all is explained!

Archibald, thanks again!

Mike
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Re: Caldercraft Northlight Puffer with working Derrick Crane
« Reply #170 on: May 31, 2010, 08:31:10 PM »

Anyone reading this section of the saga must be prepared to have their mind boggled. My lack of simple engineering skills is causing some startling solutions to problems. Those of you who have been taking an interest in the project may remember my yearning to use springs instead of elastic to maintain tension on the boom lateral lines. You may remember also that the chap in the drawing office had the bright idea of using a large ratio double pulley to achieve this. I had several 25mm chart recorder pulleys to hand, so.....

Problem 1.
               These pulley wheels had a 3.2mm bore and I wanted the secondary diameter to be 2.5mm. They also needed to be mounted from one side. So..... I made brass spindles, tapped 8 BA, so that the wheel could be secured with a washer and a bolt. The idea was to then bolt on the 2.5mm diameter bit over the top using acrylic material.

Problem 2.
               How to mount this in the lathe and produce a fairly complex shape? Decision: make it in two parts and glue together, using 6mm acrylic sheet and 8 - 10mm rod. The former I had in stock, the latter I hoped to buy at Beale Park. Sadly, no acrylic rod at Beale Park, so turned down a jumbo chunk using 4 - jaw chuck!


Starting materials.








Mounted inside out.


Showing spring.



I suppose I should be grateful that they seem to work OK!

If that's not enough to convince you I need to be on medication - there's more!

The "home made sail winch", made out of gears already "in stock", didn't swing the boom quite far enough and I couldn't get FLJ's P96 servo stretcher to behave as I wanted [I must stress that, having discussed it with Dave at Wicksteed on Saturday, he put me right on this and there is nothing wrong with the P96.] - so I decided to use a larger gear ratio, going from 48/12 teeth to 60/12 teeth.

Problem 3.
               Couldn't find a source for the latter. Bought a 60 tooth single gear.

Problem 4.
               6mm bore and a jumbo boss! Solution: Hybridization!











The new arrangement will allow for a larger winding drum with deeper channels, thus removing the possibility of the thread riding up over the edge.

Time to send fot the van and men in white coats!

Mike
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Re: Caldercraft Northlight Puffer with working Derrick Crane
« Reply #171 on: May 31, 2010, 08:56:09 PM »

Bit late in the day I know but have you tried Technobots in Totton Southampton for gears etc. our club members use them quite a lot.

http://www.technobots.co.uk/index.html
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Re: Caldercraft Northlight Puffer with working Derrick Crane
« Reply #172 on: May 31, 2010, 09:30:37 PM »

Hi Dicky,
            I've had a quick look but they don't appear to stock one to fit my need. Mind you, if I was starting from scratch, I think they probably would - my problem was starting with a mod 0.5 gear which I had to hand and then wanting to change the ratio!

Many thanks for the link to the site, it looks like a good source for all sorts of bits I might need in the future.

Mike
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Re: Caldercraft Northlight Puffer with working Derrick Crane
« Reply #173 on: June 26, 2010, 07:09:20 PM »

Talking with Steamboat Phil and NoMustang Mark at Alford, a few weeks ago, I mentioned that I was thinking of changing the steering arrangement from servo horn drive to drum drive - using a one turn sail winch. Their advice was: "If it ain't broke, don't fix it". If I had taken heed, it would have saved a lot of time and money!

The motive for making the change was that it is a bit fiddly to set up without getting slack in the "non-pulled" length of chain, especially at the extremes of rudder travel. The two bottom pulleys are adjustable for this purpose.



View from rear:



and the side:



I purchased a sail winch (17 inc. postage) and set it in the original "test bed". It was going to need a drum of about 15mm.



It soon became apparent that this diameter was going to be critical and maintaining taughtness would need the same arrangement that I had already. Introducing springs did not help, which was disappointing because they work in the boom swinging mechanism.

So: Project abandoned. If Steamboat Phil and/or NoMustang Mark offer you advice, take it!

The other thing I've had to re-visit is maintaining gentle tension on the secondary line attached to the boom.

The prototype worked well:



as did the purpose-built block, seen to the right of this picture:





With the advent of the central servo to swing the boom, however, it needed moving a fair distance to starboard and this led to unreliable operation.

So, undaunted, I decided I needed a high ratio double pulley-wheel, as used successfully in maintaining tension in the lateral boom lines.

Problem: How do you make one of these?



I don't have any 28mm round stock (or a local supplier) and even if I did, I don't have the tooling to reach that deep - so the disc had to be made from sheet. I first tried soldering the the roughly shaped disc to the hub section but it sheared off when I tried to true it up. (Probably because in trying to avoid flooding the hub section with solder, the joint wasn't good.) Thought Oh bother (or something very similar).

Next time round, tapped hub and disc 4BA and this worked but cutting the groove produced nasty noises from the tool (0.6mm wide).

The result works



(currently using a weight pending the find of a suitable spring.)

but I now find the 2.5mm section needs a shoulder on the nearside to keep the thread away from the disc as it is catching on the outer knot!

Making a new hub section is no problem but I don't fancy making another disc. Having put epoxy on the thread before assembly, I'll never get the hub section out in one piece. I'm thinking Oh bother (or something very similar)

Mike
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Re: Caldercraft Northlight Puffer with working Derrick Crane
« Reply #174 on: June 28, 2010, 08:23:31 PM »

The matter of the catching knot is resolved! I've put it inside the disc. I know, I know, Why didn't I do that in the first place?



As you can see, I've now resorted to elastic while looking for a spring. It will have to be very weak - perhaps a plastic one, if I can find one with a small enough diameter.

Going back to Martin's question of 10th October 2008: "How do you plan to overcome this?" (Yes twenty months ago!), I now feel in a position to answer: The boom falls reliably with an additional weight of 7.5g added.



This slug of stainless steel will be inserted into the end of the boom.

The reliability of the this fall is important because, if the line coming off the winding drum below deck goes slack, it will be necessary to pull the winch out to untangle it!

In practice, there could always be a small load on the hoist (probably the rowing boat) providing "belt and braces".

Without the help of forum members, I would certainly have given up - thanks guys!

A graveyard:



All of these items took a lot time to make but didn't live up to expectation! I take comfort from the thought that I'm probably not alone in this experience!

Mike
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