[PSUBS-MAILIST] Fiberglass work k-250 mbt

Wed Sep 2 12:53:59 EDT 2020

Hi Phillippe,
The method that I am using on the Seaquestor is that I am building a plug
if you will out of styrofoam that I have cut with a hot wire rig. Using a
hot wire rig once mastered will give you a really clean surface to begin
your finish. The styrofoam is a soft material and it is subject to be
easily damaged by anything. I have found that using drywall mud as a skim
coat layered on the foam gives the foam a bit of a harder shell to work
with and is easy to sand to a reasonable finish surface. Once the mud has
been shaped to my desire, an epoxy coating overtop will give it a hard
shell, but also need to be finished of imperfections if you are going to
cast a mold and then pull a part from the mold. That being said, my
preference is to cover the hardened mud with a layer of alum foil applied
with spray glue adhesive. Once covered, wax it up and add a coat of PVA
release. Then make the mold. When you are ready to pull a part from the
mold, make sure that the initial layer of gelcoat is two layers. I say this
as the foil layup process will leave micro imperfections in the surface of
the part that will need to be finished just like doing body work on a car.
The choice is to spend a lot of time and money getting the perfect mold
surface from which you are only going to pull one part, OR get thru the
part creation as cheaply and quickly as possible and do finish sanding on
the actual part. With the SeaQuestor, I have about 200sqft of surface area
with complex and compound curves, from which I am only pulling one part,
and the mold is made up of many segments to make the part and to be able to
demold it. There have been a lot of good suggestions in this thread. My
advice is to some the materials and create a testboard, and try different
methods to create a small part, even if it is a flat sheet. Any time you
can get to practice the layup process prior to the actual part is a good
thing as there is a lot to learn, and once the process is started best to
have a little bit of practice or you will have a pile of throw away parts.

Best Regards,
David Colombo

804 College Ave
Santa Rosa, CA. 95404
(707) 536-1424
www.SeaQuestor.com

On Wed, Sep 2, 2020 at 9:01 AM Philippe Robert via Personal_Submersibles <
personal_submersibles at psubs.org> wrote:

> Mike, I would like to make a mold for my K-250 MBT.
>
> James, nice work ! I think to make a plug and use it as the mold. My plan
> is to make whole front and rear MBT plug and use it to simply put
> fiberglass work on it.
>
> Le mer. 2 sept. 2020 à 07:56, James Frankland via Personal_Submersibles <
> personal_submersibles at psubs.org> a écrit :
>
>> Hi Phillippe.
>>
>> I made a glass fibre plug and mould last summer for a completely
>> different, not submarine related project, but the principle is the same.
>> This was the first time i had done this but it turned out ok.
>>
>> 1.  Make a plug out of anything more or less.  I used wood and covered it
>> with plaster of paris.  I made this spinning shape thing to scoop the
>> plaster into the correct shape.  Key is to sand the plaster utterly
>> smooth.  Even the tiniest scratch will show on the mould and eventually
>> your part.
>> 2.  Cover with wax, gelcoat and then glass fibre.
>> 3.  Pop out the plug (difficult as the glass shrinks onto the plug).
>> 4.  Polish and wax the mould.
>> 5.  Cover the mould with gelcoat, then glass fibre.
>> 6.  Pop it out.  (easier as the part tends to shrink away from the mould.
>>
>> There are lots of people with more expertise, but I didnt find it too
>> hard.   I would just crack on and give it a go.  Maybe read up on some
>> fibreglassing web sites.  Once you have a decent mould, you can bang out
>> plenty of the parts.
>>
>> Have a look at these pics.
>>
>> 1.  Initial wood and spinner.
>> 2.  Covered in plaster.
>> 3.  Making mould.
>> 4.  Mould done and polished.
>> 5.  Filling mould to make part.
>> 6.  Finished part just out of mould.  Needs polishing.
>>
>> [image: Untitled.png]
>> might help?
>> Regards
>> James
>>
>>
>> On Tue, 1 Sep 2020 at 22:10, Michael Dell via Personal_Submersibles <
>> personal_submersibles at psubs.org> wrote:
>>
>>> What shape are you looking to make?
>>>
>>> Mike
>>>
>>> On Wed, 2 Sep. 2020, 3:54 am Philippe Robert via Personal_Submersibles, <
>>> personal_submersibles at psubs.org> wrote:
>>>
>>>> Hi Mike,
>>>>
>>>> I don't figure how to make the mold from timber ? Maybe many cut
>>>> of plywood ?
>>>>
>>>> Philippe
>>>>
>>>> Le mar. 1 sept. 2020 à 01:07, Michael Dell via Personal_Submersibles <
>>>> personal_submersibles at psubs.org> a écrit :
>>>>
>>>>> Styrofoam is the problem, the timber is quite easy to surface and
>>>>> achieve a reasonable finish to mold from, i often make temporary molds from
>>>>> custom wood and brush on between 5 and 8 layers of polyester resin which in
>>>>> warm weather is usually achieved in a day, once cured i sand, polish and
>>>>> wax up... styro foam however is not going to like polyester at all... you
>>>>> could use the same method as i have discribed but coat the foam, and the
>>>>> ply for that matter with an epoxy resin then transition to a polyester by
>>>>> first coating the initial few coats of epoxy with a couple of coats of
>>>>> vinyl easter resin, this allows you to carry on with cheaper poly easter
>>>>> which is easier to sand etc. Or you could do the whole coating process with
>>>>> epoxy, i just find polyester easier to work and a lot cheaper.
>>>>>
>>>>> The other option is coating the foam with tape to get a rough part off
>>>>> then clean that up to get a mold proper...
>>>>>
>>>>> Mike.
>>>>>
>>>>> On Tue, 1 Sep. 2020, 12:04 am Philippe Robert via
>>>>> Personal_Submersibles, <personal_submersibles at psubs.org> wrote:
>>>>>
>>>>>> Hi David,
>>>>>>
>>>>>>
>>>>>>
>>>>>> I'm looking to make a mold with plywood and foam. I have a good idea
>>>>>> how to make It, but no idea how to have a good finish on it.
>>>>>>
>>>>>> I'm wondering what product to use to cover the Styrofoam and wood of
>>>>>> the mold, I don't want the fiberglass sticking to my mold.
>>>>>>
>>>>>>
>>>>>> Regards
>>>>>>
>>>>>>
>>>>>>
>>>>>> Philippe
>>>>>>
>>>>>> Le dim. 30 août 2020 à 15:31, David Colombo via Personal_Submersibles
>>>>>> <personal_submersibles at psubs.org> a écrit :
>>>>>>
>>>>>>> Hi Philippe, Are you looking to make the mold as a plug or a one off
>>>>>>> part. Let me know and I can give you some tips.
>>>>>>>
>>>>>>> Best Regards,
>>>>>>> David Colombo
>>>>>>>
>>>>>>> 804 College Ave
>>>>>>> Santa Rosa, CA. 95404
>>>>>>> (707) 536-1424
>>>>>>> www.SeaQuestor.com
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> On Sun, Aug 30, 2020 at 9:42 AM Philippe Robert via
>>>>>>> Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>>>>>>>
>>>>>>>> Hi all,
>>>>>>>>
>>>>>>>> I would like to know if someone has experience in fiberglass
>>>>>>>> making. I am looking for a starting point for making a kind of mold to
>>>>>>>> construct the mbt.  Have never work with fiberglass before.
>>>>>>>>
>>>>>>>> Regards
>>>>>>>>
>>>>>>>> Philippe
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