[PSUBS-MAILIST] R300 FRP work

Fri May 22 12:54:12 EDT 2015

Cliff, I'm on conference in Austin for August 2-7.  If by any chance you and your boat are going to be home at that time or the following weekend, I could probably manage a side trip to Devine to have a chat if you're available?

Sean

On May 22, 2015 10:19:33 AM MDT, Cliff Redus via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>Sean, good to hear from you.  I am waiting to get on a plane to
>Barcelona so this will be brief.
>From what I understand of the photos, you design the hydrodynamic
>fairing and then create virtual slices of the completed design, which
>you fabricate out of expanded polystyrene.  I presume the slice
>thickness just depends on the available thickness of polystyrene board
>Yes, I used 4'x8' x4" sheets.
>and/or how much work you want to do in shaping?  I notice that you have
>these sections joined with wire ties in the photos... am I correct in
>assuming that this was a temporary measure, and that you moved to
>adhesives etc. prior to the body filler?
>Yes, used a special spray on adhesive that joined the sections.  I used
>a CNC flat bed cutter that a local furniture fabrication company had to
>cut the section profiles based on a Autodcad drawing of the sections. 
>Bailing wire was used to temporary hold the sections until the adhesive
>set.
>
>Once you've carved the EPS down to shape, you cover in a layer of body
>filler which you can further refine and sand to a smooth finish, which
>you then painted.  Is the paint necessary?  Or can you just apply a
>mold
>release at that point?
>Paint is probably not necessary but I wanted to make sure the mold
>release worked correctly.
>
>After that, it would appear that you added flanges to define the mold
>split lines.  Were these centered on the split line, or did you move
>them slightly before laying up each half?  
>Slightly off-center so that face was on centerline plane,
>Furthermore, was it necessary
>to split left and right, or do you think you could have done the mold
>as
>only two parts?
>Not sure I could have removed the female mold from the plug mold
>without splitting down the middle.  Also it made it easier to do FRP
>layup on the haves.
>
>Do you just use a mold release on the plug and then start
>fiberglassing,
>or do you apply a gelcoat first?
>I used a mold release on the plug first.
>
>Did you lay up the whole mold at once and then cut at the flange, or
>did
>you do a section at a time?
>Section at a time.
>
>Once the female mold was finished, I presume you did some further
>finishing / smoothing to the inside surface?
>Yes, even though I sprayed a gel coat the surface was not clean enough
>so used normal auto paint procedure to paint the FRP shell.
>
>Then a mold release / gel coat / glass to create the shell?
>Yes
>
>Once the shell was done and trimmed, how did you join the pieces
>together and smooth the seam before casting your syntactic in?
>Assembled on the pressure hull and used normal FRP layup techniques to
>join sections.  This normally included grinding down the joints and
>doing a layup.  
>
>Om my next boat I am looking at generating a polystyrene plug mold 
>cut on a 3-d CNC machine.  I would then apply tin foil to plug and lay
>the final FRP shell on this.  This will give better dimensional shape
>and should be quicker.
>Got to run.
>
>
>Cliff Redus
>Redus Engineering
>USA mobile:  830-931-1280
>cliffordredus at sbcglobal.com 
>From: Sean T. Stevenson via Personal_Submersibles
><personal_submersibles at psubs.org>
>To: Personal Submersibles General Discussion
><personal_submersibles at psubs.org> 
> Sent: Friday, May 22, 2015 10:28 AM
> Subject: [PSUBS-MAILIST] R300 FRP work
>   
>Cliff - I have once again been studying your photos of the R300 build,
>and I was hoping you might be able to elaborate a bit on the process
>you
>used to construct the FRP fairing.  There are a couple of details that
>I
>am still fuzzy on...
>
>From what I understand of the photos, you design the hydrodynamic
>fairing and then create virtual slices of the completed design, which
>you fabricate out of expanded polystyrene.  I presume the slice
>thickness just depends on the available thickness of polystyrene board
>and/or how much work you want to do in shaping?  I notice that you have
>these sections joined with wire ties in the photos... am I correct in
>assuming that this was a temporary measure, and that you moved to
>adhesives etc. prior to the body filler?
>
>Once you've carved the EPS down to shape, you cover in a layer of body
>filler which you can further refine and sand to a smooth finish, which
>you then painted.  Is the paint necessary?  Or can you just apply a
>mold
>release at that point?
>
>After that, it would appear that you added flanges to define the mold
>split lines.  Were these centered on the split line, or did you move
>them slightly before laying up each half?  Furthermore, was it
>necessary
>to split left and right, or do you think you could have done the mold
>as
>only two parts?
>
>Do you just use a mold release on the plug and then start
>fiberglassing,
>or do you apply a gelcoat first?
>
>Did you lay up the whole mold at once and then cut at the flange, or
>did
>you do a section at a time?
>
>Once the female mold was finished, I presume you did some further
>finishing / smoothing to the inside surface?
>
>Then a mold release / gel coat / glass to create the shell?
>
>Once the shell was done and trimmed, how did you join the pieces
>together and smooth the seam before casting your syntactic in?
>
>Thanks in advance.
>
>Sean
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>
>
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