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questions re: max height, swap platen plumbing and thickness

 
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Lagomorph
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Joined: 26 Jul 2014
Posts: 9

PostPosted: Sat Aug 02, 2014 1:44 pm    Post subject: questions re: max height, swap platen plumbing and thickness Reply with quote

Hi all, I bought the Protoform plans a few years back, and I'm building a small table for personal use.

I had a couple questions I was hoping to get some feedback on:

I can't seem to find in the plans how to join the plumbing when swapping platens. If I have both plumbed for 3/4" PVC, how are people joining the plumbing? I did find some screw together joints in the plumbing section, that have an O-ring sandwiched at the junction. Will this work? Is there something better?

In regards to the platen itself, it describes using the chicken wire / hardware cloth that I see people using. But that makes the space between the plywood really thin (like 1/16"?) In the good old Thurston James book, it describes using 1/4" strips of wood. Is there some ideaology as to why to use a smaller space versus a larger space? Would the small blocks of wood provide faster evacuation of the air in that space?

Lastly, does anyone know what the max height of a forming buck I can put into the Protoform machine? Ie: the space between the platen and the top of the heating element?

Thanks in advance!

Lago
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crashmann
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Joined: 27 Sep 2005
Posts: 496

PostPosted: Sat Aug 02, 2014 5:15 pm    Post subject: Reply with quote

Hi Lago!

The 3/4" union should work fine for connecting the plumbing when swapping your platens. I used gigantic 2" PVC for my plumbing, which was really unnecessary, but I found a rubber coupler with hose clamps works great:



The tiny space in the middle of the platen is fine. Initially there is a large rush of air, but after that, there is not much airflow, so the tiny space would be fine. With a larger space, you have more potential for leaking around the edges of the platen.

The maximum height of your forming buck depends on a couple of factors. The general rule of thumb is that you need as much space around your buck as it is tall. For instance, if the buck was 8" tall, you should have at least an 8" distance from the edge of the buck to the edge of the platen.

However, if you have a nice organic rounded shape that tapers down to the platen surface, then you can shave a few inches off. Nearly vertical sides are much more challenging to pull than gentle slopes.

You want to avoid stretching the plastic too much. Otherwise you can have thin weak spots in your finished pull.

Charlie
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spektr
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Joined: 07 Jan 2008
Posts: 425

PostPosted: Wed Aug 06, 2014 12:48 pm    Post subject: Reply with quote

Howdy.... I use 1 inch pvc plumbing connections and clear tubing that is asnug fit over it. That way ball valves and t's and stuff is simple to rearrange.

as far as the gap under the platen.. Mine is ZERO.. I have no platen. I have dedicated mold bases. Better for what I do, but not everybodys cup of tea as it makes for more work initially.

If you are spacing a mold off a platen, I dont like screen because it sometimes gets to be dificcule to temove drom the part, so I chicken out and use popsicle sticks.... Not too tall so you suck the plaqstic inder the mold, and not too short that the airflow stinks.... Also appeals to my cheap side.....

As far as how big a part you make, thats more a function of available tank capacity, bigger parts require bigger tanks. Thats also why I have
a number pf old propane tanks on a common manifold to provide my vac storage. I used lock out the ones I didnt need to shorten part cycle times but since I got a great deal on a 220 3 phase vane pump, i dont fiddle with it any more.......
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Lagomorph
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Joined: 26 Jul 2014
Posts: 9

PostPosted: Thu Aug 07, 2014 2:06 pm    Post subject: Reply with quote

Thanks for the tips and feedback so far!
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jdougn
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Joined: 18 Mar 2009
Posts: 714
Location: Louisville KY area

PostPosted: Mon Aug 18, 2014 6:29 pm    Post subject: Reply with quote

I use "liquid suction and discharge hose" from MSC.
https://www.mscdirect.com/product/details/48432108

and their nylon quick connect fittings
https://www.mscdirect.com/browse/tn/Hose-Tube-Fittings-Valves/Fittings-Couplings/Hose-Couplings/Suction-Discharge-Hose-Couplings?navid=12105024#navid=12105024+4288201167+4288117356
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jdougn
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Joined: 18 Mar 2009
Posts: 714
Location: Louisville KY area

PostPosted: Mon Aug 18, 2014 6:33 pm    Post subject: Reply with quote

spektr wrote:
Howdy.... I use 1 inch pvc plumbing connections and clear tubing that is asnug fit over it. That way ball valves and t's and stuff is simple to rearrange.

as far as the gap under the platen.. Mine is ZERO.. I have no platen. I have dedicated mold bases. Better for what I do, but not everybodys cup of tea as it makes for more work initially.....


Spektr helped me set up his platen design. For production settings it is awesome! The mold is secure to the base and it never lifts with the plastic. Changing from one mold to another literally takes a minute. With just a little ingenuity the design can be quickly adapted for one off stuff too. Great system!
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spektr
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Joined: 07 Jan 2008
Posts: 425

PostPosted: Wed Aug 20, 2014 12:18 pm    Post subject: Reply with quote

HI DOUG.

THANKS FOR THE KIND WORDS.

CALLED A FEW TIMES, GIMME A SHOUT SOON.

SCOTT
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Lagomorph
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Joined: 26 Jul 2014
Posts: 9

PostPosted: Wed May 18, 2016 11:53 pm    Post subject: Reply with quote

I know this is an older post but finished my table. Works good!

I ended up using the coupler with rubber O ring described above to lock the platen down.

I used 1/4" wood strips arranged neatly in a pattern as a spacer between the platen layers. It evacuates the air very quickly. I'm using a 30 gallon tank and a pump.

My table is a 2x2 and I can pull 8" tall molds.

Thanks everyone for their help and feedback. I'll post pics of my build soon!
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jdougn
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Joined: 18 Mar 2009
Posts: 714
Location: Louisville KY area

PostPosted: Thu May 19, 2016 6:53 am    Post subject: Reply with quote

Lagomorph wrote:
I know this is an older post but finished my table. Works good!

I ended up using the coupler with rubber O ring described above to lock the platen down.

I used 1/4" wood strips arranged neatly in a pattern as a spacer between the platen layers. It evacuates the air very quickly. I'm using a 30 gallon tank and a pump.

My table is a 2x2 and I can pull 8" tall molds.

Thanks everyone for their help and feedback. I'll post pics of my build soon!


Great! Post up pics of your table and some pulls when you get the chance.
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