Running radius mouldings, expansion issue inner edge curling off the glass bench

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The Hobo

Well-Known Member
that's what my target is Hobo, but the matter of making a perfect master arch is eluding me, but practice makes perfect, my dustbin men are not happy with my deposits though!!!
just do the opposite to what your doing now
 

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Samson2

Member
that's a plaster off plaster mould with shellac I assume I tried a sample on the brown section in the pics above thinking to try plaster before silicone ..barsteward stuck in places but was my very first try I think I needed to myths the shellac down a bit it seemed very soft on the surface and plaster stuck to it! love to see others do this and learn a bit more but at 56 think i'm too old!!!
 

The Hobo

Well-Known Member
nice work, its a basic cast so the copy comes straight of.. how long you leaving it once its set?
pull it off while still hot or it can lift off shellac coat if its left to long that's a clear shellac on there but I don't like it sooner have the dark one /doing it this way u can make a length say every half hour
 

Samson2

Member
I bought all my covings thought far too much to make for 7 rooms all different , then made me a cracking cutting bench, sadly the bought covings were problematic wavy , different end s that were a bugger to match up but ok overall. glue and screwed
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The Hobo

Well-Known Member
View attachment 31926 its amazing what a icing syringe can do from Aldi!!!!! to fill in joints ..
I some times use a syringe from a farm supply shop big F*****g thing would not like it up my arse/but in all honesty I don't go for perfection on cutting mitres a wider jointieasier to fill and does not fall out when heating goes on/on big stuff I cut a hole in corner and feed bandage scrim dipped in a wet mix from behindwithsmalltool makes a good strong joint hope u can untangle this lot
 

Samson2

Member
my thoughts never lead me to join those specific two items , large stainless steel syringe and Arse! lucky for me the thought of it ever going near my arse is like hearing now "the cheque is in the post"
 

Samson2

Member
and laths! but have thought it might be the lath drying that lifted it so done a few with laths and hessian as can't be arsed to put it in only to see it warp then make it bin fodder. But.... I think I have sussed the technique... but still weigh the inner edge down … fan on de humidifier on and leave to dry longer and set more fully . is one half of the full arch. 1st pass 2/3mm profile under final profile as seem .. job sorted
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superspread

Well-Known Member
and laths! but have thought it might be the lath drying that lifted it so done a few with laths and hessian as can't be arsed to put it in only to see it warp then make it bin fodder. But.... I think I have sussed the technique... but still weigh the inner edge down … fan on de humidifier on and leave to dry longer and set more fully . is one half of the full arch. 1st pass 2/3mm profile under final profile as seem .. job sorted View attachment 32021 View attachment 32022 View attachment 32020
If that was run on a plaster bench,a couple of nails at each end ,hessian wrapped around the nails ,I’d be surprised if u had any problems, there’s no reason that it should be warping, even running on glass that I know of
 

Samson2

Member
it is! hence why I came on here! no warping as such the inner edge the lowest part of the profile lifting. I changed from fine casting plus to keramicast it still did the same as in "lifting the inner edge" I have two "quarters" now so happy but once I moved them and cleaned up one as decided to warp a tad can just feel its not flat but overall its a good result.. I have also a "attempt" that went mental the snips handles fit under the inner edge!!! just put some laths in place to stop it from breaking so not a finished unit. This one did move on the table. so just abandoned it and watched it move and left it to its full movement without weights to see just how far it could dry out and warp.
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Samson2

Member
two successful quarters, apart from a repairable chip from my saw!
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one run cut in half, doing so appears to stopped the expansion both halves are perfect no lift, funny thin is I even tried a shorter length before that lifted .. finding the right process is the key, method etc .. baffled at the same time happy a result not for the bin..
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The Hobo

Well-Known Member
if u had run it insitue I would have been decorated by now hope your not on time and mat bigger bill than trumps wall lol
 

Samson2

Member
and I agree with you in-situ is looking the right option, but on the bench is a mess that's easy to clean and not splattered everywhere. Perhaps I'm better paying for it but getting the lad, right lads around here is not easy.. i'll bollock on … plus i'm a tight t**t as well
 

The Hobo

Well-Known Member
and I agree with you in-situ is looking the right option, but on the bench is a mess that's easy to clean and not splattered everywhere. Perhaps I'm better paying for it but getting the lad, right lads around here is not easy.. i'll bollock on … plus i'm a tight t**t as well
you Yorkshire lol
 

mikeadams1985

Private Member
run it on a proper bench
I suspect because ts on glass its lifing of very easy, as the plaster sets it swells and often causes movement, being on a proepr bench where its stuck to the bench a bit better might help.

ive ran millions of spins and never had it curl as you say, only thing is i dont run on glass.

What are you reinfocing with in the
he cast?
 

Vincenzo dupris

Active Member
Hi , I am running some window mouldings on a glass bench approx. 4 inch wide using Fine casting plus , the straight runs are only 1.5m long and are spot on but the radius are warping from the inner upwards on a radius of 2feet/ dia 4 feet tried making them in half but still they curl up from the inner thinner edge.. I have tried Keramicast as advised by the reps but even that's doing the same ...Doing my head in I can get a great running mould completed then it curls any advice greatly appreciated Lads.
I run mine on glass
 
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