Page 2 of 2 FirstFirst 12
Results 16 to 21 of 21
  1. #16
    Join Date
    Feb 2003
    Location
    back in Alberta for a while
    Age
    68
    Posts
    12,006

    Default

    Quote Originally Posted by woodman-79 View Post
    Cheers Ian,

    I have a question though.
    There are two types of cutouts I need to do;
    1. I need to cut the fibreglass out of the existing holes where the LED's stick through the base - this I think will work well using a razor/stanley knife and following your suggestion and Cal's advise.
    2. I need to rout out some recesses/access panels through the fibreglass as well as the ply substrate.

    Do you think cutout #2 would also be done at the time you suggested, or would you wait for all coat's to be done then cut that out.
    I just down want the router to pull the fabric at the edges and make a mess if its not fully hardened.
    cutting the glass for existing holes can be done once the epoxy is tack dry. You may get some tearing inside the hole, but nothing that can't be smoothed over and "fixed" when you do the fill coats. The advantage is that the fill coats will also coat the inside of the cutout.

    Pygmy Boats recommend that cutouts be done with a jig saw AFTER all the fill coats, but this is so the cutout can be used as a hatch cover. I know of no reason not to make the cutouts after the first coat of resin has hardened. The advantage is that subsequent coats of resin will paint the inside of the cutout. I have only used a router as a cut out tool once and that was to trim laminate. For this reason I can't really recommend a technique or the appropriate bit. Personally I'd feel more comfortable cutting the cutout to approximate size with a jig saw and then cleaning up the edge with a router cutter. A spiral cutter appeals because it makes a shear cut, but I'm not sure that they can also make a plunge cut.
    Last edited by ian; 23rd October 2018 at 12:17 PM. Reason: remove redundant text
    regards from Alberta, Canada

    ian

  2. # ADS
    Google Adsense Advertisement
    Join Date
    Always
    Location
    Advertising world
    Age
    2010
    Posts
    Many





     
  3. #17
    Join Date
    Jul 2012
    Location
    Kinglake
    Posts
    79

    Default

    Cheers Ian,
    In this case I have no need to keep the cutout section as it will end up being a rebated cutout, and the panel that goes back in will be of 4mm glassed ply, whereas the form is 12mm ply.

    I have both up and down cut spiral bits and am quite familiar with routing so I have that bit covered. Questions were more just on the technical aspects of cutting fiberglass and carbon fibre as I've not used either before.

    I think I have enough to proceed. I'll probably play around with some scrap bits first anyway and see how it goes.

    Oh actually, one other question: I am planning to stick a couple of broomsticks through the square channels and mount them on something to allow me to rotate the hole thing like it's on a spit when I do the fibreglassing. This should enable me to get it all done without putting any epoxied parts on the table. On this note, I was watching a video of how to put carbon fibre on car parts and in the video they put a base coat down first and wait for it to become sticky, then they apply the carbon fibre to it and it sticks on - this makes it easy to do complex shapes without it pealing off where its upside down if that makes sense. The base coat acts like adhesive. Is this standard practice? It seems like a good idea in my case as it will stop the carbon fibre from pealing off when the form is upside down.
    Once the carbon fibre is stuck on the base layer, they then go on to wet it out like normal.
    Thoughts in this method?
    I'll post some pics when it's finished. I think it will look pretty shmick (unless I completely botch the fibreglassing)

  4. #18
    Join Date
    Feb 2003
    Location
    back in Alberta for a while
    Age
    68
    Posts
    12,006

    Default

    Couple of thoughts on this

    does the lip of the rebate need to be glassed or just epoxied?

    I should have asked earlier -- why are you glassing the form? Usually glass or carbon fiber is used to substantially reinforce a construction. Does your 12 mm ply really need reinforcing? I can see why you would want to waterproof it, but a reinforced skin?

    The Pygmy Boat instructions suggest that bare ply should be undercoated before glassing, but the recommendation is to allow the primer coat to fully dry before glassing. This is so the fabric can be easily draped over the shape.

    If you are working by yourself, I'd worry about your ability to maintain a wet edge if you were to try and wet-out and squeegee the glass over the whole form in one go. (The rod would also need to be covered in a non-stick covering -- possibly mylar.)
    Perhaps best to plan on glassing the "Top" and "bottom" separately. If you use Blue tape to define the join line, the wetted fabric can be cut and the blue tape removed while the epoxy is still tacky. Once the first coat is dry aggressively sand the edge and then repeat the process for the other side. And once dry sand the overlap.
    You then should be able to apply the fill coats to the whole form in one go.

    An alternative to the rod would be a nail board.

    A tip.
    I've found that waxed kitchen paper is an effective means of protecting my bench.
    regards from Alberta, Canada

    ian

  5. #19
    Join Date
    Jul 2012
    Location
    Kinglake
    Posts
    79

    Default

    First up, just so we are on the same page, when I say 'glassed' I am referring to the carbon fibre - there is no actual glass cloth involved in this.

    Quote Originally Posted by ian View Post
    does the lip of the rebate need to be glassed or just epoxied?
    Just epoxied as the glassed panel that covers it will... well cover it so it can't be seen.
    That said I may cut a really narrow strip of carbon fibre and epoxy it in on the vertical face of the rebate in case any of that is visible as a small gap.

    Quote Originally Posted by ian View Post
    I should have asked earlier -- why are you glassing the form?
    Purely for aesthetic purposes. The fixture will look like carbon fibre rather than ply...
    You should get a fair idea of the look I am aiming for in the pictures earlier in the thread.
    There is some degree of needing to make it moisture resistant as well but that's a secondary concern.

    Quote Originally Posted by ian View Post
    If you are working by yourself, I'd worry about your ability to maintain a wet edge if you were to try and wet-out and squeegee the glass over the whole form in one go. (The rod would also need to be covered in a non-stick covering -- possibly mylar.)
    So to be clear, the plan is tol glass the continuous surface from top around the curved side underneath and back up the other curved side, meeting back at the starting position.
    The flat ends will not be done so the rods passing through the channels won't be in contact with any epoxy.
    In terms of scale, the fixurtre is 1056mm long and around 350mm wide. I would have thought you could quite easily wet out a 700mm by 1m area in one go couldn't you?

    Quote Originally Posted by ian View Post
    Perhaps best to plan on glassing the "Top" and "bottom" separately. If you use Blue tape to define the join line, the wetted fabric can be cut and the blue tape removed while the epoxy is still tacky. Once the first coat is dry aggressively sand the edge and then repeat the process for the other side. And once dry sand the overlap.
    I don't want seams. While it wouldn't be obvious if I used glass - using carbon fibre it will stick out like dogs balls and ruin the aesthetic.

  6. #20
    Join Date
    Feb 2003
    Location
    back in Alberta for a while
    Age
    68
    Posts
    12,006

    Default

    Like you I'm using "glassing" as a general term which in this thread means using carbon fiber
    Quote Originally Posted by woodman-79 View Post
    So to be clear, the plan is to glass the continuous surface from top around the curved side underneath and back up the other curved side, meeting back at the starting position.
    The flat ends will not be done so the rods passing through the channels won't be in contact with any epoxy.
    In terms of scale, the fixurtre is 1056mm long and around 350mm wide. I would have thought you could quite easily wet out a 700mm by 1m area in one go couldn't you?
    based on my experience with the kayak ...

    some wet epoxy will overflow the ends and potentially bond the rods to the substrate -- so I suggest a bond breaker just for ease of mind.

    the type of epoxy I used combined with the ambient temperature limited me to a maximum 6 oz mix -- any more and the brew in a flat 4" paint tray would go off around half-way to 2/3rds through application. When that happened I'd toss the remainder of the mix and the applicators and make a fresh batch.

    a 6 oz batch of epoxy was enough to wet out an area (with 6 oz fabric) about the size of half your form -- say 1 m x 300 mm -- after squeegeeing the excess out of the fabric I was pushing it to maintain a wet edge down the center line. The advice in the construction manual was to glass the hull in one session working alternate sides of the center line. In your case each curved side will likely require two positionings of your form. Squeegeeing is needed to force out any air trapped under the fabric. With internal corners the process is more time consuming than you would think.

    Epoxy squeegeed out of the fabric can't be reused because it us full of air.

    I note that the form has a number of sharp 90 degree corners. If at all possible fillet or round these corners -- it will make glassing much easier.
    regards from Alberta, Canada

    ian

  7. #21
    Join Date
    Feb 2015
    Location
    Strathalbyn South Australia
    Posts
    1,141

    Default

    Just an aside from the fever of using epoxy and carbon fibre, have you thought about the effects of using either of these materials are going to impact the inhabitants of the aquarium? I ask as I am aware of tank manufacturers using specific calking to make the tanks due to normal silicon being toxic to fish. Have you done any research on the epoxy or the carbon fibre and there effects on aquatic life. Epoxy gasses off for a very long time after manufacturing, you would be devastated if you lost your entire tank to this.
    Just food for thought. [emoji848]

Page 2 of 2 FirstFirst 12

Similar Threads

  1. Some Carbon Fibre
    By bdar in forum WOODTURNING - PEN TURNING
    Replies: 6
    Last Post: 1st August 2012, 09:22 PM
  2. Carbon Fibre
    By GRS in forum CNC Machines
    Replies: 6
    Last Post: 5th July 2012, 08:26 PM
  3. Carbon Fibre No. 2
    By bdar in forum WOODTURNING - PEN TURNING
    Replies: 6
    Last Post: 27th May 2011, 07:41 PM
  4. Carbon Fibre No. 1
    By bdar in forum WOODTURNING - PEN TURNING
    Replies: 6
    Last Post: 26th May 2011, 08:25 PM
  5. Carbon Fibre cloth
    By Reno RSS Feed in forum GENERAL ODDS N SODS
    Replies: 0
    Last Post: 17th June 2009, 04:30 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •