Thermo-forming Corain column wraps

[Crazyraceguy]

This is a new challenge for the big oven and vacuum press. The head of the solid surface department and I have been working on this project. We need a total of 3 complete sets. They are about 75" tall and a little over 37" in diameter. This is too big to do in "half", so we need to make quarters and glue them together. It's not as easy as it seems. The edges don't stay straight enough to join back together, so a jig to straighten them was needed. This is in addition to the one used to form the sheets and two more to glue them together. We built 2 of the ones shown so that the halves can be joined later on-site. The ends have 8mm x 50mm Dominos to align them.

 

[afish]

Thats cool, there are some places doing some amazing thermoforming work out there. I saw a large reception desk that didnt have a straight line or consistent radius in the entire thing. I can only imagine how many segments it took to make or the cost. more than my first house im sure...

Is that vacuum press and oven a new addition to he shop?

 

[Crazyraceguy]

No, it has been here for about 2 1/2 years. We have another (much smaller) unit that does long, narrow strips for edges of radiused counter tops. That way the big unit doesn't have to be heated up for small parts.  I use the vacuum press portion of the machine far more than the heater. It is great for glue-lam bending as well as pressing things like double-thickness shelves. You get far more even pressure with zero clamps. That's how I did all of the shelves for the bookcase in the mock-up photos from a couple of weeks ago. That's about to come back up too. It's back from the finish department, so final assembly and more pics next week.

 

[squall_line]

How much rebound does the Corian have?  Or because it's more plasticky, does it stay put after thermoforming?

My understanding of steam-bending, at least, is that you have to account for rebound.  Not sure about glue-lam bending or Corian, though, so I'm curious.

 

[afish]

Does that vacuum press use a silicone or polyurethane membrane? looks like it has a phenolic bed.

 

[Cheese]

The edges don't stay straight enough to join back together, so a jig to straighten them was needed.

This is in addition to the one used to form the sheets and two more to glue them together. We built 2 of the ones shown so that the halves can be joined later on-site. The ends have 8mm x 50mm Dominos to align them.

Do you have to use a heat gun to help straighten the edges?

Could you make the "quarter" a bit larger than needed and trim it back to the correct size with a fixture and a router?

This is pretty interesting...and probably pretty nerve wracking because the customer is looking for product and you're still trying to fine tune/develop the many processes needed.  [smile]

 

[WastedP]

I found with thermoforming curved solid surface wainscot panels that it was easiest to design the mold an inch and a half smaller than the sheet in every direction.  This way the sheet didn't have to be perfectly lined up with the mold, and then after the inner form was out, the sheet could be flush trimmed to the edges of the form to get the final size right.

The coolest thermoforming project I've ever seen were the armchairs at Grand Central Station.https://www.sterlingsurfaces.com/grand-central-chair

 

[Crazyraceguy]

[member=41832]WastedP[/member] we do a somewhat hybrid approach. The parts are indeed oversized, because the edges will never be acceptable for gluing. We don't make the parts bigger than the form though, just make the form bigger. I have, in the past, accidentally cut the part too large for the form. At that point, the part was bent around the edge, requiring more trimming than I intended.

[member=44099]Cheese[/member] Yes, the parts are slightly oversize, so they can be cut back to the actual size needed. The halves need to be glued together at a specific diameter, and actually turnout round. In the end, they will get a cap that makes a bit of a ledge. Those parts will definitely be round, so these need to match.

[member=73094]afish[/member] it is a silicone membrane, pretty thick too. When it is cool (room temp) it is tight enough to not droop, but after a few cycles of heat, it sags a bit. It's rather amazing how far it stretches.

[member=75217]squall_line[/member] it has no spring-back at all. Once up to the proper temp, it is soft enough to be called limp. It takes a bit of wrangling to lift it up onto the form because it's so soft. It will lay right down over that form with nothing but its own gravity. It really only needs enough vacuum pressure to keep it from curling up as the exposed side cools faster than the side touching the form. Some care has to be taken with the form construction, because the vacuum can be raised enough to crush a badly built one.
There is another form that we used to rest the pieces in for cutting the straight edge. The first one was done laying in the other form like the one in the pic. I rigged it up to have a flat plane to cut the edge with my MFK700. It was just not stiff enough to give a good edge though, so we abandoned that idea. Then we went to following a straight edge with a router, but it is just too hard to clamp, without the clamps getting in the way. We finally settled on the TS55 and FS3000. It's a little long, but the FS1900 won't reach. I have had a FS2424 on order for weeks, at the local supplier, but it still hasn't showed up. Apparently they are backordered?

 

[afish]

I thought it looked like silicone. thats really the way to go IMO. I started building one but got bogged down with other jobs. my plan is to use silicone when I get back to it. 

 

[Crazyraceguy]

I'll get some better pics of it next week, when we get back to it. Oven open, vacuum drawn down on a part, assembled unit out of the glue form, etc.

 

[Michael Kellough]

I’d like to see the rig for trimming edges if you get a chance.

 

[Crazyraceguy]

Sure, no problem.

 

[WastedP]

Tracksaw with a good blade sounds like the most efficient way to trim those edges.  You know the radius, so you could cut blocks to support the rail, just hot glue them to the Corian.  All of my thermoforming was done before I had even seen a tracksaw.

 

[Crazyraceguy]

The last pic is the form itself. We clamp the piece in place, set the angled platform on top, then use track clamps to secure the whole thing. I set the saw at a 1-2 degree bevel to be sure that the outside edges make contact first.

 

[WastedP]

That's awesome.  Wish I would've seen your setup ten years ago.

 

[Crazyraceguy]

That's awesome.  Wish I would've seen your setup ten years ago.

It would have been quite different. We were cramped into a small space, did not have the beam saw, sheet goods storage was significantly less, and we only had a single 5' x 12' CNC machine.
We did have an oven for Corian, but it was only capable of 6" wide material and 72" length.
A job like these cylinders would have been sub-contracted to a local company that was far more equipped for that kind of thing.

 

[tallgrass]

This may sound odd, but where do you get the Corian? IT seems hard to find in sheets. I live in the Los Angeles area and I can not find it. Is it one of these only from the manufacturer kind of things?

 

[guybo]

Hi, local fabricators sometimes have lots of remnants they will let go.

 

[afish]

Years (ok decades) ago when I used to use it some. You had to be a certified fabricator to use it.  You cant buy full sheets of the rack anywhere.  It was a little more popular back then for residential work.  Not sure if things have changed since its not real popular anymore.  Personally, I would not use anything but white for things like CRG does such as reception desks etc. The stuff that is supposed to mimic granite just looks cheap and plasticky to me.  The seamlessness is nice so for commercial kitchen, prep areas it is still good when function is more important then looks. Not sure what the prices are these days.  Back then it wasnt cheap and with the cost of resins and everything else It is probably pretty pricey so its probably no cheaper than granite or quartz. 

 

[WastedP]

It is still cheaper than stone, but the gap has narrowed because of Chinese and Indian stone hitting the market in huge quantities, coupled with massive container-ship accessible slab processing facilities in Saudi Arabia.  Corian has stayed about the same, in relation to laminate, but natural and engineered stone got cheaper (both in price and quality).

You still need to be a certified fabricator to buy Corian.  The requirements for LG Hausys material is a little fuzzier.  There are a lot of small off-brands that will sell to anybody with money and a shipping address.

The newest generation of adhesives is about twice as expensive as it used to be, but the increased viscosity and faster cure time is worth every penny.