BuildingAfloat

[BikerAfloat]

I notice on your design the X rails are the same length of the box seciton. I would leave about 5-10mm clearance at both ends to ensure they lie flat in case the box section is distorted at the ends.

Was looking at that, I think I will do that as it gains me some extra working area too, for not a lot more cost.

1) Bear in mind the holes in the SBR rails look like they've been drilled by an ape swinging on a pillar drill - you can sometimes even see the pencil lines which mark where the holes go, so don't expect them to be accurate. Make the frame and gantry then mount the rails to the frame by drilling and tapping one hole at a time until you have them aligned and running smoothly, then drill and tap the rest.

Yes I thought they'd be added manulally after cutting, that is why I plan to drill to suit as you suggest!

3) I found recently that a local shop is cheaper than getting the pulleys and belts online, plus no long delivery time and additional delivery time to send back the items they got wrong!

Not sure in the wilds of Cambridgeshire will be that advanced, but I'll have a look!

6) I reckon try LinuxCNC then mach3 then Planet CNC because clearly if you get on well with LinuxCNC then you've saved a lot of money compared to the other options. If not by all meant buy mach 3. Either way don't expect to learn much if anything about Linux though, since one it's installed it's just like using a program on windows.

I like the Linux price, but it's uncharted waters! And yes I guess I'll be too busy making stuff to learn much! I'm stll very much in favour of the Planet CNC stuff as the BOB and software are less than Mach3 and I believe the USB BOB has some buffering to help with the non-realtime windows performance. Would be best to be able to try all three hands on, or at minimum get a copy of the manuals to compare features & interfaces.

Foam is an interesting idea, by all means try it but I don't think it would help that much with resonance. As far as I know the issue is not the 'air resonating through the centre', it's the walls of the steel box section that vibrate. To prevent resonance on the not moving parts you should add mass, or some material with good damping properties which tends to be materials made up of particles which rub against each other to dissipate the energy as heat. Sand covers both criteria, but it sounds like that's not an option.

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Mmmm, as Jazz has tried it without success (Thanks for that Jazz) the foam seems to be a no-no. I will have to see how the boat is when the machine is done. Sand can always be added later if I make the boxes "water tight" from the start. I guess if it is too noisy and the sand becomes a must, I can always use the router to make book cases along much of the other side of the boat. That'll give me an excuse to by more books as they are needed for ballast!

Cheers Geoff.