boat stuck in mould

Sounds great Whacker. Don't forget to rinse out the rag really really well between grits or you will be wasting your time.

Have a great sanding weekend.


Allan

 

oh i will, i think i even like doing it, its almost theraputic,
i also compounded the a part of the mold to see what it comes out like, started with the 200, and finished with the 500, and gave it one lick of release wax, ive never seen it so shiney. cant believe the way it came out, it should have been done as soon as i bough the mold. always learning.

 

Whacker

Another minor suggestion: when I first started, I placed a piece of masking tape every 18" on flange or so, along the length of my mold. I used the tape as a marker to help me keep track of where I had sanded or waxed.

I now have permanent markers on my mold flange. I used a scratch awl to create a shallow groove and filled it in graphite powder/ epoxy putty to create a fine black line.

The markers really help me get into the "groove" of sanding/waxing without having to focus where I am along the mold. I overall each step by about 3" to make sure I don't miss an inch.

Hope this helps,


Allan

 

its funny to read all the differant methods and way peole do things . but its good to read !! there are so many good things come from such a post and every one learns !. most of my sanding i do with a small palm sander they have variable speed and are nice and small so can sand curved surfaces in most cases. Remeber sanding a 20 foot hull with one in each hand !! worked really well and made a terrific job abd a lot quicker than just using a big sander wet and dri sanding witha air sander and water is really good and much quicker than doing it by hand , plus dont get those dreaded deep sanding marks that take ages to get rid of .

 

Tunnels,

I would love to use a air sander if I could find one with a small soft pad that would conform to the inside of my canoes. I have been researching sanders and the closest I have found is by Mirka, a company from Finland (http://mirka.com/) So far, I have only used their sandpaper (mesh actually, which is incredible. Is there a sander a manufacturer that you would suggest?

I really appreciate the time you take, to go into such incredible detail in your posts. They are very helpful to me.


Thanks in advance.


Allan

 

http://www.toolfetch.com/Category/Air_Tools/Air_Sanders/CP7200S.htm?nogs=1

here is a mini orbital sander could be close what you need .

http://www.shinanoinc.com/si/product/detail_sanders/si_3118.html
This is the brand i was using but a much older modle than whats listed !!

Can use water with a electic sander just use a sponge for the water with bar of soap!!, soap the sand paper and sand and wipe occassionally with the sponge as long as it stays wet it sands really good . Hand soap is better than liquid soap of any sort . i do the same when i wet sand as well !!! ,the paper lasts longer and the soap lubricates and holds the dust in suspension . Everything stays clean when you dribble water over the surface and theres never a chance ever of getting wax of silicone transfer because of the soap . dont be silly and use lots of water !!!! Yes its dangerous and if you kill yourself dont come running to me pointing you finger !!!, if you still got one that is !!!!

 

i was wondering could i sand the hole mold using 800grit and 1200grit followed by compound, there is a few star cracks so i sanded them down using 800, and 1200, and hey presto they were gone, there is also a few scratches in there i wonder could i do the whole mold this way, if i could it would make the mold 100% again. or would i destroy the mold

 

Whacker,

I don't think it would do any harm at all. Do you have anything paper finer than 1200?

After you pull your first boat and are sure you are happy with it, you might investigate the idea of adding a few more layers to FG to the outside of the mold to stiffen it so that it doesn't flex. Just thought.

Allan

 

Thanks Tunnels,

I am more than a bit leary about wet sanding with an electric sander.


Allan

 

You can sand and buff the entire mold, but even though it looks great now those cracks will come back right away, probally after the first part is pulled from it.

 

Ondarvr,

Why will they come back if they are sanded out? Do you think Whacker would be wasting his time sanding to remove small star cracks? I don't imho.



Whacker,

Don't sand any specific spot deeply. You would end up with a low spot in the mold and high spot in the actual boat.


Allan

 

i was thinking of that alright if the first hull is perfect ill def put more fg on the outside. fingers crossed.
progress so far. im sick to death of sanding now at this stage all day today and all day tomorrow, ive blisters and birds eyes in my fingers. but on the plus side it should be done tomorrow or monday at the latest cause im going for a few pints tomorrow evening.
i deserve it so i do.
looks well, progress is slow but rewarding.
im going to sand all the mold down. my face was no more then six inches away from the mold ive seen lots of little imperfections, slight scratches in the mold, also when the mold was repainted some sand im guessing got stuck in the keel and was painted over and is hard inside the skin of the mold, this will be coming out. i cant imagine this would help in the release.

 

Sanding a mould after a mishap is ok and just take it from square one like brand new again . all the usual coats of wax etc etc but pva this time and for ever more each and evertime you use it .

Star cracks !!
these only appear to have disapeared from sight but are lerking there still just waiting to reapear later on .
This is from the mould being hit from the outside .never hit a mould ever !! the gel coat is like egg shell and simply had no guts what so ever thats why thickness on products and moulds is so very important .
i can never stress this enough !,do the job properly and the right way and problems are a thing of the past and life is boring .

Remember the boat will star crack as well if you hit it from the inside !!!! so simple dont hit anything !!!!

 

Tunnels,

Why would you gel coat a mold it makes it so "tender".

I have made two molds, each out of 1 layer of 4 oz. fg and then 10 layers of 10 oz. fg. There is zero print thru. I used west system epoxy and post cured both at 120 degrees F for 24 hours.


In the future I plan on switching to polyester resin to gain a higher TG.

Would you agree with that revision?


Allan

 

Mould making is a individual thing . if you got good mould from the method you have why change ??
I understand the price of materials is often the factor that is not to be ignored .
If you do change better to start with vinylester resin with more hardness and less shrinkage and then finish the bulk with polyester .
if i owned a mould and saw anyone go near it with a rubber hammer he be asked to change direction and head for the door drop the hammer and keep walking !! more damage is cause by unthinking people hitting and banging and in general giving a mould rough treatment than any other cause .
where does print through come from ? so if you understand what makes it happen then dont use tha material !! Core matt is a good blocker and adds thickness pretty quick . your not making a boat so no need for fancy fabrics
. and in a few years will be under a tree some where ant take a 1000 years to break down maybe