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Member postings for Dave Cooper 6

Here is a list of all the postings Dave Cooper 6 has made in our forums. Click on a thread name to jump to the thread.

Thread: Returning modeller
07/10/2020 23:51:07

Jim - just catching up on the thread, and, a few extra items on the electrical /radio side :

Like you, I had a broken battery connector on my Futaba /Acoms Tx. Mine was a spiral wound one rather than a flat tab that you reported. (I was checking the audio by-pass filter at the time and caught my sleeve in it !). The wire quality to the main PCB is not great and doesn't really like solder - mine has failed twice. I would reinforce carefully with good quality wire and add some heat shrink sleeving for extra support on the repair.

Dave M recommended 4Max as a supplier for the wattmeter. Although they deal mainly in aircraft stuff they are a really good supplier and give good general advice on chargers, motors etc.

It's worth looking at the "XT60" type connectors. They are a really nice little unit especially for on-board battery use. There is a 'big brother' as well for carrying the larger currents...

Dave C

Thread: Motors/prop for model warship
01/10/2020 21:45:51

A few random thoughts :

I once saw a boxed set of "Model World" for sale on an internet auction site. Price was on the high side, but, I'm kicking myself now.

Hmm, 3" beam sounds narrow(ish). I suppose if the CG is low enough it should be all right.

I have a 385 in a fast, planing hull with a 30mm /3 blade prop. It doesn't seem to get hot at all - I expect this is breaking all the 'rules' though.

Nice choice of subject. I think I can visualise a rotating scanner and (randomly) moving turrets. Arduino maybe ?

Dave

(ps I did say they were random !)

Thread: Machine Tools
15/09/2020 20:05:20

Hi Tim and Ray

Thanks for the warnings and comments. I should reiterate that the present set-up is just to see me through until I can find a lathe and a proper mill...

Some light grinding this afternoon on a piece of brass allowed working to about 5 thou" (hard to be exact without a DTI or digital calipers) - this with a rotary grinding wheel and brass work piece in the X-Y table.

There was some tool chatter, and so, I stop and check the chuck at regular intervals. Also, I let the Cub cool down in between runs, so, no need to report me to the RSPCA just yet Ray !

Incidentally, my local 'CNC' machine shop (who can work to 6 microns, so they say) charges £65 /hour. So, you don't actually have to do all that many hours to clock up the price of a good lathe.

Dave

15/09/2020 13:05:05

Above photos show a trial set-up of the new X-Y Table with the venerable Wolf Cub.

The jury's still out on accuracy ! First test was to rout a block of medium balsa. - this went well with the grain but needed a little clean-up with an X-Acto chisel across the grain. Certainly good for bulk removal of material though using a ball-ended Dremel cutter.

Next tests will be in metal. Probably one milling job followed by a vertical turning in brass I expect.

I think it should be alright for small boat parts. Cost so far under £100...

15/09/2020 12:52:49

x-y table 1.jpgx-y table 2.jpg

12/09/2020 11:07:30

Well the 'X-Y' vice arrived this week and it looks very similar to the second photo from Paul T.

It was a budget model and needs a bit of work. The threads and ways are fine but some of the castings will need a clean up around the edges. Also, there is some play in the thread registers /receivers and these will probably need a spring or maybe a bushing or two to remove.

All-in-all, not bad value for the money and 1,000% better than what I've got now ! No doubt it will further my engineering a little...

Dave

03/09/2020 21:24:53

Lots of good advice again guys - thanks.

OK - sentimental admission time : I recently lost a very old screwdriver at one of our R/C slope flying sites. It wasn't even particularly good, but, it was my favourite !

Also, the Wolf Cub was my Dad's (I haven't seen him since I was 21, but that's another story). It's been professionally re-wired and checked for safety etc and runs well. I have several other makes as well, but, the main thing is that it has a round, parallel collar which enables a secure clamp to the drill press. All my other drills have weird tapers, lumps and bumps and things in the way...

My wife says I much prefer my old clothes to new ones - I think tools must be like this too ?

03/09/2020 10:41:14

A quick update :

I've taken the plunge and ordered a 'X-Y' machine /bench vice. This is not a high-quality unit (the reviews are very variable), but, it will enable a bit more engineering learning.

There are trapezoidal threads which will probably need some cleaning up with a file - maybe even supporting via a SIF bronze bush or two.

My low-tech "Wolf Cub" based drill press has a worn front bearing and about 0.5-1mm of side play. So, I'll search the net for a replacement bearing asap.

Also purchased a set of titanium drill bits in 0.5mm steps with a set of adjustable reamers to come (73rd birthday today !).

No lathe as yet, but I think I've now got a better handle on size and built-in facilities etc. Cost new will be about £1,500 (ish) so, a bit more saving up yet.

Dave

29/08/2020 13:41:39

Some very interesting comments and ideas so far - thanks all.

Size-wise, I seem to be falling somewhere between the 'mini' range and the big stuff (quite often 3-phase though)...I'd like to stay 240 volt /single-phase if possible.

We now have a Lidl near us so, will keep a watch out for anything that looks good. The dual-axis (x / y), drill press theme is one that seems worth pursuing.

I'll keep watching, listening and looking for the time being.

Dave

28/08/2020 18:03:32

Thanks for the response both.

I have a sort of make-shift drill press at present but it's based on a 1950's Wolf Cub (single speed) 2400 rpm ! A bench grinder (2 wheels) is in almost constant use. A good vise rounds off the current crop apart from the usual hand tools.

For usage, the largest item at present is a suspension assembly for a racing sportscar. Max. diameter here will be around 45mm - materials: T45 tube, EN14 bar and 300M bar.

I also have plans for a model 4-stroke engine around 10cc. Hence smallest item probably the pushrods 14 gauge silver steel perhaps. Oh, and lots of boat plans - mainly, sailing next.

Yes, I think my preference will be to save for a new set-up as second-hand can be tricky as you say...

Dave C

28/08/2020 11:09:27

Hi All

Apart from the more obvious use of band and jig saws etc, I was just wondering what machine tools modellers find most useful.

I have in mind, especially, lathes and mill drills. There is a space on the end of my bench approx. 4 feet long and a spare corner space which could be used for a free-standing mill.

Any advice on suitable sources and experience of 'new' versus 'used' welcome...

Regards,

Dave

Thread: Boat?
17/08/2020 14:43:46

Hello Richard,

Some very good, practical advice from the others.

I think there are quite a few considerations as well - building space, tools (including machine tools), timescale, budget (?), not to mention distance from sailing water (assuming a working model).

Probably, at the top of my list would be 'inspiration'. This will help carry you through the difficult bits to arrive at a finished model. Have a look at plastic kits (huge variety these days) and Youtube videos. Also, visit the different manufacturers' websites eg Model Shipyard, SLEC etc, and, look at the 'Albums' on this forum to give you an idea of what can be achieved.

Tons of help here once you're a little further down the road...

Dave C

Thread: How to measure what motor I need.
30/07/2020 11:06:03

Florian - a few thoughts :-

I'm afraid I can't advise on the final power train combination (I'll leave that to the experts)...but, I would do the floatation /ballast test first.

Reason : you may need a 'double-hull' approach. This would be an extension 'downwards' ie to increase stability and to lower the centre-of-gravity of the whole model. This can then contain additional ballast if necessary.

I did this on my little fast launch quite successfully and it does give some extra protection to grounding on hidden rocks etc below the surface.

If you do go this route, you may have to alter the prop shaft thrust line and hull exit point....

Hence, I would do the float /stability test first and put in some extra ballast to represent motor and batteries. Then give it a good wobble !

For the superstructure windows, I drilled a small (say, 2mm) hole near each window's corner (assuming square or rectangular windows), then cut and file to join up the holes.

Dave

26/07/2020 16:34:14

30 Kg - wow, that's going to take some shifting and transporting...

I expect you are planning a purpose-made launching trolley /model slipway ? (Most probably you are in a different age bracket to me !).

I suppose the ballast could be added after the model is in the water ? Just thinking outside the box now.

Good luck with the project - let us see some photos please,

Dave C

Thread: MTB 49
24/07/2020 14:34:56

Just a note on scale deviations :

If making an exact (static) scale model from the boatyard's /designers drawings, then you could reduce every linear measurement exactly. It would be pretty tedious and I'll bet that most scale modellers will make a 'compromise' some where.

Even plastic kits aren't exactly to scale, as to reproduce many of the smaller components would simply make them too fragile to handle.

For a working model some compromise is inevitable. Mainly in the hull volume area, most of the ones I've seen make the hull deeper than scale to give it good flotation /performance etc. They may also be slightly more 'beamy' and perhaps length-over-all is stretched a little too.

Enjoy your build (and don't be afraid to compromise a little !).

Dave

Thread: 3 Motors RC Boat
16/07/2020 11:18:08

William - if it isn't a rude question, how big is your water ? Have a look on Youtube at some of the really fast racing boats. They cover an awful lot of water in a very short space of time...

I see you're into motorsport - how do you fancy jumping straight from a Formula SAE into an F1 car ! (I found it difficult enough going from FF2000 to F3).

Seriously, even though you're experienced in R/C cars, I would plan a more gradual progression and leave the really quick stuff for later.

Have fun,

Dave

Thread: Returning modeller
09/07/2020 10:52:32

Hi Jim

There seems like a lot to learn at the start ! The best advice I can give is to find what works for you.

Inevitably, you will make purchases which don't work out. Put these in the 'spares' box - they'll come in handy one day...

Two further bits of advice :-

1. Join a club - benefits too long to list !

2. Test on the bench first (especially battery life), then in the bath - leaks, power test, rudder and prop under load etc.

Most importantly - have fun !

Dave C

08/07/2020 22:04:24

Back-tracking the thread a little, and just a quick addendum on the NiCad thing....my latest information is that whilst they are illegal to sell, they are still legal to use. I use one in a RC slope soarer glider powering just the Rx and two control servos.

Having said that, they do suffer from the 'memory' and 'black-wire corrosion' problems and are not very planet-friendly !

I think they still have a use on the bench as a temporary power source for testing, but, one by one, my models (including the little RAF launch) are now converted to LiPo power.

Connectors: (Power) I suppose everyone has their favourite(s) - I am slowly standardising on the "XT60" type, but have gold-plated 'bullet' connectors in one model. Both work well. I find the bullets are easier if you need a quick change. (Radio) I'm slowly standardising on the Futaba colour code as I find this the least confusing...

Good luck with your project,

Dave C

Thread: Auxiliary Drive for Pride of Baltimore
25/06/2020 10:47:22

I'm just wondering what, exactly, is the purpose of the auxiliary motor(s) ?

Is it just to get the boat back to 'base' if the wind dies, or, is there is a scale application here - ie does it need to supplement sail power in order to achieve scale speed ?

Context: I'm learning about scale sailing and have a need for something auxiliary on Yacht Ardent (mine may well be a little electric outboard hung off the stern though...)

I'll follow the thread with interest !

Dave

Thread: Yacht Ardent
24/06/2020 23:57:47

Yes Ray - quite a lot of Permagrit tools of various sizes in almost constant use, but, I am a bit space limited at present.

I think though, moving things around a bit I could make space for a scroll or band saw if it had a small 'foot-print' on the bench ?

My trusty hand fret saw at the ready though with a selection of blades ! Plans to be ordered soon once one or two other projects further advanced...

Dave C

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