Vintage Gentleman’s Cruiser

[Bob Abell 2Participant @bobabell2]

Paul

I've paid some really silly prices at B & Q for bags of screws etc

Amazon is a great shopping source for me these days

Bob

[Paul TParticipant @pault84577]

Bob

1m long M6 stainless steel stud bar at the local engineering supply shop is 70p

B&Q Don't do stainless steel stud bar so the nearest thing is BZP and it costs a lot more.

Paul

[Bob Abell 2Participant @bobabell2]

My word……That's very cheap for stainless steel!

Is it for your trolley?

Will the trolley have enough height reach, to get over the pond wall at Haydock?

I'll bet you've overlooked that?

Bob

[CookieOldParticipant @cookieold]

Bob , The lock nut idea will work 100 % , see ya and paul at Haydock.

Best Regards Dave

[mike farrellParticipant @mikefarrell21522]

Hi Bob Well I use Crocs (soft plastic shoes ) because I need to take off on entry to her domain (lazy really ).Pleas ekeep up the entertainment .Looking forwards to Haydock. Hope to have a project to show you and Paul something different ,ducted fan jets and all Michael

[Bob Abell 2Participant @bobabell2]

Thanks Cookie and Mike

Pleased you like the Morecambe and Wise Show

This is a live show………Totally unrehearsed

See you boys at the 'dock in August

Bob and Paul

[Bob Abell 2Participant @bobabell2]

Hello Cookie

The locknut idea has fallen on stoney ground!

Can't reach the nuts without removing the motors

Plan B…….

Add a further grub screw at 90 deg to the original?

That should do it?

Will need to make an accurate drilling bush

Bob

 

Edited By Bob Abell on 15/07/2015 08:00:38

[ashley needhamParticipant @ashleyneedham69188]

Bob. Stop being complicated. get some loctite 222 and this will stop the grubs from getting loose.

Ashley

[Bob Abell 2Participant @bobabell2]

Ashley……Thanks

How does Loctite 222 perform with 4mm screws?

Can they be undone later?

You do realise, that if things go wrong……..Lady Joyce gets it!

Bob

[ashley needhamParticipant @ashleyneedham69188]

Bob. had same issues on proj No2.

Loctite 222 is formulated for small screws, and is a low-strength formula (compared to the usual one that you buy at a motor-factors or b&q) )so they can be undone. 4mm grubs are a reasonable size so u should be ok.

The grub screws on my meccano bits are a wierd old english course thread unfortunately. The last test saw them all get loose..despite having been tightened BEFORE the test, and the boat was only out for 3 mins.

Ashley

[ashley needhamParticipant @ashleyneedham69188]

NB….further additional grub screws will only make the gears/pullies even more out of balance and vibrate more and exacerbate the issues you are having.

Ash

[Bob Abell 2Participant @bobabell2]

Many thanks Ashley

In the meantime, I've had a mild brain wave!

I have removed the pullies and fitted a longer grub screw, complete with nut and pre set the inside protrusion to about 6 thou and used it as a driving dog!

Like it?….Like it?……Wink!…….Wink!…….Know Warra mean?

Sorted?……..lf not, then I'll try the Loctite suggestion

Bob

[Paul TParticipant @pault84577]

Hello Bob

When reading about your latest brainwave involving the long grub screw and nut my first impression was to agree with Ashley as the off centre load would be unbalanced and precipitate increased vibration.

But then I thought that Bob is a practical engineer and would have taken the motors apart to balance the shafts so vibration wont be a problem.

Paul

[Bob Abell 2Participant @bobabell2]

Thank you, Paul

Yes I've done that already………Say's Bob with his fingers crossed

As a matter of fact, to the discerning eye, there is a possible glaring design error with the timing belts, which will cause vibration!

Nobody will spot it, in a month of Sunday's !……….But brother Geoff did……..As he is a qualified engineer!

With multiple timing belt drives, there is every chance that some of the belts will fight with the pulley teeth……Hence the vibration!……..Similar to gears which are slightly out, relative to the keyways

But clever Bob has got round the problem with today's brainwave……..All the pulleys now have a little rotational clearance

I'm the greatest, I'm the best……I've seen me and I'm impressed!

Bob

[Paul TParticipant @pault84577]

Bob

I'm glad to hear that you are the greatest but I am all at sea with your last post especially the bit where you say that clever Bob has got round the problem…………which problem are you talking about and what was the solution of which you are so proud?

Sorry to be so thick.

Paul

[Bob Abell 2Participant @bobabell2]

Hello there, sorry to cause any confusion, old chum

The initial main problem was the grub screws coming undone

That was solved with the long grubscrew and nut idea

The vibration problem was caused by the timing belt teeth clashing with the pulley teeth…..On some of the drives

I've got round that problem, by having a bit of slop in the grub screw drive

How does that, grab yer?

Bob

[Paul TParticipant @pault84577]

Hello Bob

Sorry but its a clear as mud, how are the belts and pulleys clashing and how does slop in the screw drive help.

Paul

Edited By Paul T on 15/07/2015 14:19:40

[Bob Abell 2Participant @bobabell2]

Paul

Timing belt drives are similar the gear drives…..Teeth meshing with teeth

There's no problem with two pulleys and a belt

But the Abell drives can have clashing teeth

Two belt drives driving one final pulley is the culprit!

When the second belt drives the same pinion, the first belt may be just in advance and try to do all the work

In other words, the drive will keep jumping from one motor to the other

We are only talking vibration…..So by having a bit of slop in the grub screw drive dogs, the belts will have room to manoeuvre……..Back and forth slightly

It must be a strange sort of drive train, where the drive comes from two sources

I hope you agree with this cock and bull story……lol

Bob

[Dave MilbournParticipant @davemilbourn48782]

You mean 'a bit of slop' like this???

Words once again fail me.

Edited By Dave Milbourn on 15/07/2015 15:29:18

[Paul TParticipant @pault84577]

Bob

I am very sorry but I am completely mystified by your explanation, I have visions of drive belts and pulleys going in all directions.

I have even tried sketching out what you have said but didn't get anywhere so if you have the time could you do a drawing to illustrate what you mean.

Paul

[Bob Abell 2Participant @bobabell2]

That's quite right

Why do words fail you?

What are you insinuating…….Given that the system works fine!

Belt stretch hides most of it

Bob

[Gareth JonesParticipant @garethjones79649]

Bob,

Can you explain what you mean in your post when you say 'Similar to gears that are slightly out relative to the keyways'

I can't see how the relative angular position of the gear wheel teeth and its keyway can have any effect at all.

Also the thought of having significant angular backlash in a drive system does not seem a good idea to me – it just seems a recipe for accelerated wear to take place between the driving dog and keyway.

Gareth

[Bob Abell 2Participant @bobabell2]

Gareth

Only time will tell?

I'm guessing, but we would have a similar effect with a car engine

If a piston fires slightly early or late, we would have a similar effect……..This must surely happen?

The point is, when running on one motor and the second motor is powered up, the system powers up without any problems

Bob

[Bob Abell 2Participant @bobabell2]

All this must explain why the present grub screws are perpetually coming loose

Looking at the motor demo run video, issued in April, the system runs quite nicely

When the grub screws are firmly secured, we may get a different set of conditions

Running the motors in fresh air, is completely different than in the water, as the motors have something to drive against……Then, hopefully, belt stretch comes to the rescue

I wonder, is there any way of synching the drives as they run?…….That would be nice?…….Belt tension is a possibility?

Bob

[Paul TParticipant @pault84577]

Bob

Now I understand.

Belt tensioners might be a good idea ….. a small wheel on an adjustable arm could be the answer.

Do the drives really need to be synchronised, when all is said and done we are discussing a model boat that wont have excessive use.

Paul

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