A 7 metre variant of SibLim

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  • 18 May 2018 08:59
    Reply # 6241617 on 6240496
    Annie Hill wrote:

    Well now you know the set up for cutting things and that it's all feasible, why not just saw up the plywood for the model by hand? Treat yourself to a nice, 1/2mm wide blade Japanese hand saw and it won't take long.  They are a delight to use, anyway.  Then all you'll have is the cost of the plywood and the glue.  Also, sawing up the different components will give you a closer sense of the boat.

    But that would do very little to prove the accuracy of the CNC - there are also some very small bits involving the tabs and such. 

    If making the model works then not much can go wrong on the real size version and people with limited skills and infrastructure should be able to knock one up.

    Oh and right now I am rather busy building a house so anything that saves me some time is fine by me. 

    And I certainly don't plan to mess about carrying 30 sheets of ply up 100 steps from the road to my workshop so that I could carry the parts back down to the garage where assembly will take place. 


  • 18 May 2018 08:26
    Reply # 6241608 on 6010674

    In the UK, the leader in the field of production of plywood kit boats appears to be Jordan Boats, in Somerset. They will take any design, and produce a kit of the plywood parts. So, when we're a little bit further on in proving the design by CNC-cutting a model, this would probably be the place to go, for UK builders,  as they already have a lot of expertise.

  • 17 May 2018 21:56
    Reply # 6240496 on 6239049
    Gary Pearce wrote:
    Gary Pearce wrote:And the answer for the cutting is: AUD 387.50 PLUS the cost of the ply.

    The "sweet spot" for the ply looks like the Birch at $136 so thats $272 for the ply so thats AUD 659.50 total. 

    Which is a very large amount for a 1.2 (ish) metre model boat that will never get wet but one needs to consider this as a "design cost" from which others may hopefully benefit in future.

    We shall see.


    Well now you know the set up for cutting things and that it's all feasible, why not just saw up the plywood for the model by hand? Treat yourself to a nice, 1/2mm wide blade Japanese hand saw and it won't take long.  They are a delight to use, anyway.  Then all you'll have is the cost of the plywood and the glue.  Also, sawing up the different components will give you a closer sense of the boat.
  • 17 May 2018 11:34
    Reply # 6239049 on 6149723
    Gary Pearce wrote:

    Ironically the CNC for a model will be quite a lot higher pro rata as the cutter needs to be around 1mm or less, you have to move much more slowly or you snap the bit. 


    And the answer for the cutting is: AUD 387.50 PLUS the cost of the ply.

    The "sweet spot" for the ply looks like the Birch at $136 so thats $272 for the ply so thats AUD 659.50 total. 

    Which is a very large amount for a 1.2 (ish) metre model boat that will never get wet but one needs to consider this as a "design cost" from which others may hopefully benefit in future.

    We shall see.


  • 11 May 2018 23:28
    Reply # 6149723 on 6149707
    Annie Hill wrote:
    Gary Pearce wrote:

    Brunzeel (Brookvale) have 1220x2440x1.5 hoop pine for AUD 80

    Crumbs - I'm paying about that for 6mm okoume plywood I'm putting into my boat!
    Ironically as the ply gets thinner past a certain point the price increases rapidly. I was given some 0.6 mm 3-ply samples yesterday which cost a whole lot more again. 

    6mm "BS1088"Gaboon  (Okume) is AUD 110, 9mm is AUD 129 - regular 1088 is 72 and 95, but thats list price. 

    Oh and you are right about grooving the bulkheads,  one might get away with a shallow groove, or one just might not be bothered.Especially as when you pay for CNC you are effectively paying for the length of the path and the speed it takes to run that path. They run a simulation and it tells them how long the machine will take. Adding grooves could add a huge amount to the cutting cost. 

    The other CNC shop I have used did a flat AUD 75 per sheet last time, but that was for kitchen cabinets and doors. Those machines rip through 18mm HMR MDF

    Ironically the CNC for a model will be quite a lot higher pro rata as the cutter needs to be around 1mm or less, you have to move much more slowly or you snap the bit. 


  • 11 May 2018 22:57
    Reply # 6149707 on 6148739
    Gary Pearce wrote:

    Brunzeel (Brookvale) have 1220x2440x1.5 hoop pine for AUD 80

    Crumbs - I'm paying about that for 6mm okoume plywood I'm putting into my boat!

    BTW: your thought about routing grooves on the plywood: it looks effective, but you need to be using quite thick plywood if you do this, otherwise you will be substantially weakening it.  Especially if the grooves happen to match up on either side.


  • 11 May 2018 13:34
    Reply # 6148870 on 6148859
    Gary Pearce wrote:

    I wonder if tabs on the case ends (fore & aft)  into the bulkheads might make things more foolproof but need to think if thats possible for assembly. 


    Yes, I thought of that, but it doesn't look easy. Stn 3 and stn 4 need to be slotted into the berth sides first, and then stn 1 can be slotted onto the forward end and the berth sides can be sprung inwards enough to slot in stn 6. If, then, the berth flat is to be slotted in, there needs to be enough give in stn 4 to permit that. It may be that the board cases can be slotted into stn 3, which would get the angle and position right, but not stn 4. It may be that with only shallow tabs for positioning, not wedged tabs, stn 3 and stn 4 can be sprung apart far enough to get the board cases in.This is what the model is going to do - prove what can and cannot be reasonably easily done. On Annie's boat, we built the cases in situ, having glued the fore and aft ends onto the bulkheads at an early stage.
    Last modified: 11 May 2018 17:48 | David
  • 11 May 2018 12:38
    Reply # 6148859 on 6148743
    David Tyler wrote:

    Gary, thanks for the heads up on the missing line. I've added it, and uploaded a new version.

    Yes, the board case position markings are just that. The cases will have to be made up separately and then fixed to the bulkheads. I was hoping that they could be marked along with the grid lines, but if that's not possible at model scale, it shouldn't matter. They would be useful at full size, but if it can't be done, then we can add some dimensions and pencil them on.

    I imagine the hoop pine is a bit soft and weak for the details of the tabs, maybe? I think I'd go for the DMK birch. Mister Ply seems far too expensive for what it is.

    Cheers for the line. 

    FYI the CNC folk only need a pen tool to add the daggerboard lines. Full size they suggest a small groove. 

    I wonder if tabs on the case ends (fore & aft)  into the bulkheads might make things more foolproof but need to think if thats possible for assembly.  Of course full size one could put vertical grooves in the bulkheads to look like a nice boarded effect .... if you were painting them :-)

    CNC folk are recommending the birch which they have used before and like so thats probably the way to go. 

    I will let you know what transpires.


  • 11 May 2018 09:20
    Reply # 6148743 on 6010674

    Gary, thanks for the heads up on the missing line. I've added it, and uploaded a new version.

    Yes, the board case position markings are just that. The cases will have to be made up separately and then fixed to the bulkheads. I was hoping that they could be marked along with the grid lines, but if that's not possible at model scale, it shouldn't matter. They would be useful at full size, but if it can't be done, then we can add some dimensions and pencil them on.

    I imagine the hoop pine is a bit soft and weak for the details of the tabs, maybe? I think I'd go for the DMK birch. Mister Ply seems far too expensive for what it is.

    Last modified: 11 May 2018 09:26 | David
  • 11 May 2018 08:56
    Reply # 6148739 on 6147117
    David Tyler wrote:

    A new version of the one sixth scale parts drawing, with the side decks added.

    And thats the one I took to the CNC folks today. Actually not the CNC folk I have used before but a "mom & pop" outfit recommended by my plywood supplier (for my housebuilding joinery) Brunzeel in Brookvale. 

    Once on the CAD a few minor discrepancies emerged. These would be easy for him to work around but its probably best long term if the master drawings are amended.

    Station 3 is not joined at the top and so can not be cut out. It appears to only require a straight line across the top.

    It was not immediately clear what the dashed lines for the daggerboard positioning were. On his CAD they appeared as tab holes that were not closed off at the ends. but on QCAD they just look like dashed lines which confusingly exceed the boundaries of the station. Are they markings of some sort for the daggerboards ? This particular shop don't normally use pens for marking and scribing marks into 1.5mm ply sheet is not really possible. 

    Oh and he said he has some nesting software which may improve ply usage - he will see.

    On the plywood front I have prices from 3 suppliers for 1.5 mm ply.

    Brunzeel (Brookvale) have 1220x2440x1.5 hoop pine for AUD 80

    DMK (Brookvale) have 1220x2440x1.5 birch (we think) for AUD 136

    Mister Ply&Wood have 1200x1200x1.5 for AUD 143 (i.e. AUD 286 per full sheet)

    I should get a quote from CNC shop mid next week and may then try a second CNC house if the price seems too high.

    Cheers


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