Never Use Poly!

[DodgeViper]

Here here, agree with DV.
dxiw, I buy poly, machine it, and use it without any worry whatsoever. I'll be willing to wager a vast amount of people who would use a waterblock also either have a window in the side of their case or leave the side off. It's only natural for most to want to display what they got goin on in there. That being said, there will always be a market for poly topped blocks no matter how much disinformation is spread by the ones who cannot do it right.

This is a first, LOL. I would bet that Plexiglas is being used. I have in the past used a table saw to cut Lexan and beleive me you can not use Plexiglas on a table saw. I beleive the top is made of Plexiglas as the top splitered when trying to cut it.

Mask don't give up on clear tops. You need to order Lexan that you can make sure is what you receive. Both sides of the poly will be marked that its Lexan on the peel off paper.

 

[country_3030]

What about covering the poly with a sealentaround the barbs. Like what they use to seal model airplane tanks it is clear and works on any plastic. It can probly be found at hobby town usa or hobby lobby.

 

[JFettig]

I do have enough lexon to make some tops, its just that do i want to? i only have 1/2in lexon, the screws are only 1/2inch long, that means i would have to spend MORE money on these etc... i mite just have to do this... *sigh*

do you guys see any problem with me plunging the hole down 1/8inch into the lexon so the screws will fit?

 

[The Spyder]

nope~ just make it CLEAN...............

 

[JFettig]

I wanna hear this from G_F because i know he has first hand experience with poly, Im going to take a top down stairs and mill it into 2 peices, see if it gums up...

 

[JFettig]

I went nuts on it, and this pic will speak for itself

 

[DodgeViper]

The problem your going to have is if you use a drill bit the the poly will have a tappered hole at the bottom the reverse match of the drill bit. You want a flat shoulder. Hell the screws are cheap. Just chalk it up as a learning experience and buy longer screws.

 

[DodgeViper]

I bet that what you have is Plexiglas. Lexan is not going to split like I see.

 

[JFettig]

here is what an axe does to a 'poly' top

i can plunge it with a flat bottomed end mill....

 

[gone_fishin]

Looks like acrylic to me but the pic is not so clear. That is not what it looks like when I carve out my chambers, only slight fuzz at the cut edge and no gumming.

If you plunge the area for the screws, add a plastic washer under the screw, go down a quarter inch in the half inch poly. Just buying some new screws would be easier though.

 

[JFettig]

yep, its all gummed up along the edges were i milled, and the break is clearish, just the same as a break in what i know as acrylic... does poly even break? i mite have to take the axe to some of what i know that IS lexon, i got 2 6x6inch sheets of lexon rite here..

is the washer needed? or just a precaution, i shoudl take it..... but i think the longer screws mite be cheaper. Im not sure if i can find these nice button head screws....

 

[Daemonfly]

If I were looking to buy your block, I would deffinately want the lexan, especially if it's 3/8"-1/2". More material = more protection, and it barely weighs anything.

As for the screws, I like the look of countersunk cap screws - just a suggestion

Hopefully you can make up for your current losses and gain some profit from sales.

 

[Highlander944]

This is getting out of hand...

Hey guys,

This is getting out of hand here. I'm the guy who manufactured the blocks for Jon. I can tell you that I have a material certification on hand that states the top is Polycarbonate. I will call the supplier to confirm this.

I can also tell you that GeminiCool has used Polycarbonate on about 99% of all our blocks. I'm not certain what I may have told DV about Plexiglass, but we have never used Plexiglass/Acrilic in our product. It is entirely possible that I miss spoke when describing the material early on. At one point we did experiment with some PET-G, however that was for a very minimal amount of product.

I have talked to product support on several occasions. There appears to be no difference between Lexan and Polycarbonate for this type of application. I will go one step further and actually call GE Polymers to confirm this from the 'inventor' themselves.

Now, polycarbonate IS prone to stress cracking. That is an issue. A nylon material would not be so prone to this type of failure, however it would not be optically transparent. A HUGE factor in cracking tops is hose installation. ANY force applied to the perpendicular hose barbs WILL stress the top. I suspect that 1/2 tubing amplifies this situation do to additional weight of the hose. 3/8 and 1/4 systems are less prone to cracking, simply because the amount of stress on the top is less because the weight is less.

In general:
The tops are/were polycarbonate to the best of my knowledge, always. Polycarbonate is Lexan and there appears to be no benefit to 'either' in this type of application. Polycarbonate IS prone to stress fracturing. So ANY pressure applied to the barbs (especially hose pull) can crack the top.

I hope this clears things up a bit.

Peter.

*NOTE I've just confirmed that the material ordered and delivered was clear LEXAN. This is a GE product and deemed the "best" polycarbonate.

 

[Highlander944]

Hey DV.

Hey DodgeViper,

You are absolutely mistaken, your material is not Plexiglas.

You were one of our early customers, however there is no chance that your top was Plexiglas. The 'worst' it could be was a product called PET-G Vivak, however I believe that there were only about 5 tops made from this material and I can account for 3 of them. Thus it would be most likely that your top is/was polycarbonate.

I have talked with GE. Lexan is produced by GE and it is their trade name, everyone else makes polycarbonate. Now you could argue that GE makes 'better polycarbonate', however Lexan and Polycarbonate are the same. There are different 'types' of Lexan. They add isolative properties and also mark guard technologies, however as per GE directly, this would not appear to impact the structural stability that effects our stress fracture issue.

I said it just above and I'll say it again. I believe most of our cracking problems are now do to stress introduced by the hose on the fittings and I believe that 1/2 hosing amplifies that problem.

Peter.

 

[gone_fishin]

I think your problem is in the machine tapping process. Stress from a hose is not going to do that alone (grab it with two vise grips and try to crack a 1/2" chunk after you drill a hole in it), you need the material to be scored before it will crack. If the machine tap process scores the thread area vertically or chips the threads then a weak point is created for pressure to induce a crack. A top could also be in good shape when made but after repeated insertion of barbs, a thread could get chipped. Permanant barbs are a better solution.
My latest solution is poly rod lathed to have a lip and bored out, then permanantly welded into the hole (liquid weld) drilled into the top. A poly barb will be strong, it will have appealing looks, and the threading process is removed (it's a pain in the a** time consumer anyway).

Highlander944, what do you think of that procedure? I would hope that a solution is found in the commercial market so that this paranoia of clear tops will subside.

 

[Highlander944]

hey gone_fishin,

That sounds pretty good. I am reasonably sure that the machined tapping cycle as you put it is highly reliable and is not 'chipping' any threads. Infact, I would say with 99 %confidence that the rigid tap cycle in our CNC equipment is more reliable than hand tapping in this application.

The stress I'm speaking of is the 'pulling' of the hose. The barbs are at 90 degree angles from the poly surface. Thus, any pressure applied at the end has an increased effect on the shallow threads. I believe this pressure along with the thermal cycling decreases the reliability of the poly tops.

I did call GE. Their product is warranted against braking and cracking but NOT the type of cracking we have been experiencing.

ok.. on a side note... we will introduce two new tops for our blocks. We have poly and copper already... we are now making Al and White Nylon, that may be colored.

 

[Caffinehog]

One way to tell for sure if it is acrylic or polycarbonate is to try to burn it. Acrylic will burn quite nicely, like any plastic, and melt. Polycarbonate will not like to burn at all, and will turn all bubly and black, and will become soft, but not really melt much.

Another way to tell:
Real polycarbonate is extremely flexible, and will take a beating with a hammer without breaking. It will be deformed and all, but....
Acrylic will shatter if hit with a hammer.

Yes, I have tested this.


I'm not sure of the properties of vinyl or plexi.

You can procure clear vinly, acrylic, or polycarbonate sheets at www.usplastic.com

 

[DodgeViper]

I remember back when I bought my Gemini High Volume block. I and Hoot were the first to have these blocks. The block served me well until the top broke. The top breaking was my fault it slipped off the counter onto the tile floor. Now the G. E. Lexan I used which was 1/8" recently I could take and fold 180 degrees wilthout it breaking. This Lexan does not appear to be optically clear, but has a slight yellow tint to it.

Peter, I would like to get a replacement top for the GHV. In another thread I have offered the block free to a beginner to water-cooling that is trying to keep his cost down under $100.00 dollars.