Broad Ambition - The Model

[grendel]

more bearings arrived in the post, including 2 complete bearing blocks, so a quick spacer printed, and ready for a trial, and a successful one too I think.

 

[grendel]

well it is a lot quieter, a few more mods need to be done, as the motor is drawing over 2A (it should be less than 1A ideally, this shows that something is still binding, but it is running smoothly compared to before, more investigations - more work, and a bench to build tomorrow.

[grendel]

So this morning an early start in the workshop, everything has been tidied out of the way, and the dry fit has been knocked down (noting the order it all came to bits) the bad fitting joints have been cleaned up, itsall ready to be fitted back together with glue and screws, first though I have some chores to do, and I need to pick up at least one pair of longer clamps to clamp the frames together before screwing it together. so when I go shopping I will need to pop into a diy shop for those.

[grendel]

Well shopping all done and 1 clamp bought (when I saw the price I decided I could manage with 1) and gluing, screwing and clamping took place, the frame is now up.

[grendel]

Oak top on, this went on as odd boards  of tongue and groove, then I had a rethink and decided not to use laminate for the sacrificial layer this time, and went with my original plan of 1/2" ply. a nice trim at the back edge to stop bits going down the edge of the ply top, and its nearly done, just got to sort the shelves and under top storage.

[grendel]

I have spent all day working in the workshop, racking has gone up for storage bins, and I have picked up some sash clamps at the bootfair, one of these had rusted so the threaded section would not turn, so this was sorted, heated it up and eventually got it turning.

I managed to clear one table off, so thats now gone, and the table saw sits in its space, this leaves the whole central area clear.

I fixed the vice to the bench to assist the freeing of the clamp, however I didnt like where I put it so its been unbolted and moved, I will leave it unbolted for a bit to see if this is where it works.

the last job out there today was making a couple of bench hooks to save the bench when I am sawing, one standard left and right hand, and the other right hand and mitres, 2 boot fair saws were sharpened, one I am not sure about because the tooth geometry looks more like a japanese saw, with only 30 degrees between the front and back of the tooth.

[quo vadis]

A proper mancave 

[JennyMorgan]

41 minutes ago, quo vadis said:

A proper mancave 

But where's the beer pump and spirit optic?

[ExSurveyor]

Seems to be a bit of a thing going on on this forum with sorting out workshops,  I hope it isn't contagious

[MauriceMynah]

I can assure you it is NOT contagious.

[JennyMorgan]

I don't doubt that that blue barrel is for biofuel rather than alcohol based products!

[MauriceMynah]

Correct (sadly), and the insulated thing behind the barrel is the 200 litre processor.

[Hockham Admiral]

I hold my hands up in both amazement and supplication in all of this talk!

When I'm back home it's my turn to try and rationalise my THREE sheds into one new one.           

[MauriceMynah]

Easy, get a really big shed and put the other three in it.

[grendel]

Mine is only tidy because it hasnt had time to get full of junk and untidy yet.

[grendel]

here are the bench hooks I made last night, tonight was sorting tools (note no progress on the models as I need some longer than normal m3 screws, these are now in transit, and should arrive tomorrow or wednesday.

[grendel]

longer screws have arrived, now looking at the motor mount plate it is a fraction off alignment, another will be made taking much more care to align everything.

[grendel]

lightbulb moment, I thought I had carefully aligned the motor, I got the manufacturers data sheet with the drawings, and aligned the bearings with the dimensions from these, I had noticed things ran better when pressure was placed on the back of the motor. so time to recheck everything, the coupling was removed and careful measurements taken - yes things were not lining up, I was slightly off on the vertical, but the horizontal, well the bearing was too high, while perfect alignment isnt critical, it helps to be in the ball park, add to that - the brass mounting plate isnt flat, well my materials box has been raided, some aluminium plate has been found, this weekend it will be out to the workshop and on to the precision tooling. yes careful measuring tells me the bearing needs to drop about 1.4mm and align better vertically, I have also found a stiffer brass sheet for the base. version 2 coming up, I have a brass spacer to replace the plastic one I printed (just needs drilling)the brass block will also act as a heat sink to remove the heat from the motor.

So I am disappointed I cocked up in the first place, but I am determined to get it right - last time I trust the manufacturers drawing.

[grendel]

I took a punt and ordered a 35mm prop (current one is 30mm) I have tried it on model #1 and its too big, but I have looked at in on model #2, and it looks feasible, so one way or another we will get the extra power. model 2 can have the skeg angled down a fraction to clear the prop - its tight - less than 0.5mm between the blade and the hull, but its doable. I also got a 30mm prop with a fraction bigger blade size, so when I get the motor mount sorted it will be testing time.

[JennyMorgan]

Peter, just a thought, with only .5mm  clearance between hull & blade then might there be a risk of crud being trapped and stopping the prop from turning? Minute sheer pins perhaps?

[Wyndham]

Good read as ever Grendel and I raise my hat.

I comment with hesitation, I don't want to offend in any way, if I'm stating the bleeding obvious feel free to tell me so.

Are you sure the misalignment is from an error in measuring? Looking at your first picture the problem could be caused by a baseplate that isn't flat, a printed spacer that isn't parallel or a bearing hole in the aluminium off square. any one of them will cause a problem 

I was looking at your last pictures and thinking " what would we do".  As you've identified, first off, get that mounting plate flatter and sturdy (if space permits), it's the foundations, easy from there.

Is there enough play in the screw holes to correct the vertical alignment? If so, line up, tighten them and dowel in place for a more secure fixing.

 

[grendel]

Thanks for the Thoughts Wyndham, yes my thoughts have followed along the same lines as yours, the two parts I am sure about are the bearing block and the spacer, as for the measurement, I know what I desighned the spacer block around, so I know that measurement is wrong - now. I could have spaced the motor up with washers, but that wouldnt cure the baseplate, so a rebuild is under way.

JM, the clearance isnt a lot more on model #1 and even with weed round the prop at beccles she kept going, at the moment it is an option that can be used if the standard prop doesnt give me enough speed without the gearbox.

[grendel]

Looking at this now I am more awake and at work, I neglected to say, that the difference is about 1mm on the height of the bearing, this means I can raise the baseplate by that 1mm (or make it 1mm thicker) and still have the clearance i need. at the moment I am looking at two options, one is a thicker brass plate or secondly an even thicker aluminium plate, trust me I shall be measuring the clearances very carefully before I start building the new baseplate, - if the thicker aluminium plate will fit, it will be used. once I have model #1 sorted I will do the one for model #2, this will be easier as I have been holding off the construction work to keep the clearance to get in to the hull on model #2 for measuring etc (in case you were wondering why I had not cracked on with model #2)

I wanted to get this little problem solved before progressing to a stage where I had to do any deconstruction to be able to fit the proper solution. I want to get the current draw down to about 1A when running, with no load its 0.5A, so I dont expect to get it that low when the prop is doing some work, but 2A plus seems a bit much to me

[grendel]

the plastic spacer will be replaced by some 1/4" thick Brass bar I have 6.4mm is about the perfect height for the new spacer (the old one was printed at 7.8mm, and came out at 7.7mm, once installed I can eyeball the two shafts and file the spacer to give me a perfect fit, from my pictures the shafts are currently off by not quite half the diameter of the prop shaft (4mm) so between 1.2-1.6mm the spacer reduction is 1.3mm so it will be in the ball park, ready for fine tuning. I also now have my workshop up and running so can drill the holes using the proper pillar drills etc which will increase the accuracy of those (rather than using a hand held drill). you work with what you have at hand, and the first attempt was really just a proof of concept anyway.

[grendel]

a busy day so far, shopping done and out to the workshop, the new stiffer baseplate has been constructed, everything lines up, out of the boat its drawing 0.6A, but its still at 1.5A in the boat running at full speed the motor gets warm after about 20 minutes running, the prop shaft gets warm, I am thinking of removing the wood support and re packing it into position to see if I can get it running smoother. I am wondering if the wood support is too high at the back, lifting the end of the prop shaft and trying to bend it. the good news is that its running quietly.