[PSUBS-MAILIST] Fiberglass work k-250 mbt

Thu Sep 3 01:24:49 EDT 2020

Thats a good system David, i have done similar plugs/molds using drywall
mud over different substrates but rather than epoxy I've brushed on several
layers of LSE polyester resin, up to 6-8 coats in one day which can then be
sanded back and polished to a high shine finish, assuming the time has
first been spent fairing up the mud layer to a reasonably good finish. The
polyester is easier to work and a fair bit cheaper than epoxy... I have
managed to get quite a few releases off some of the more straight forward
shapes...

Mike

On Thu, 3 Sep. 2020, 2:55 am David Colombo via Personal_Submersibles, <
personal_submersibles at psubs.org> wrote:

> 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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>>>>>>>>> Personal_Submersibles at psubs.org
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>>>>>>>>>
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