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My 2 X 3 Design (pic heavy)
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felixx
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Joined: 21 Sep 2009
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Location: San Diego, CA

PostPosted: Mon Oct 12, 2009 6:05 pm    Post subject: Reply with quote

Here is an updated pic. I chose to use 1/4 MDF for the sandwich and supports. Instead of 4 separate strips (like in the tutorial) i am making a gasket by cutting a square hole (so that it looks like my concept in an earlier post).

there should be enough room for the frame to sit on the table as well as the frame that holds the plastic when it comes down.

still on the hunt for a 30 gallon water heater tank i can scoop from somewhere.


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spektr
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PostPosted: Tue Oct 13, 2009 12:33 am    Post subject: Reply with quote

I'd go back a machine or 2 and reread what a friend of mine had happen when he didnt properly seal his platen. If you are using MDF, it WILL leak very badly and probably not hold vacuum unless you seal it. I suggested how to save what he had built. It works fine now. IIWY, I'd bore a hole in the table top for clearance for a plumbing flange, and use a nipple to get thru the tabletop for vac hose hookp. I'd seal the exterior of all sides of the platen that dont see heat with silicone caulking, ESPECIALLY THE BOTTOM THAT TOUCHES THE TABLETOP. I'd even use 3 or 4 coats of shellac. before the silicone. If you want to try something, kiss a piece of mdf and suck air thru it and see how porus it is... it will suprise you.. Scott.
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felixx
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PostPosted: Tue Oct 13, 2009 1:01 am    Post subject: Reply with quote

I have every intention on sealing it. I bought some sealer for the platen. I can always make a new platen if this one doesnt work the way it is suppose to.
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jegner
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PostPosted: Tue Oct 13, 2009 6:02 am    Post subject: Reply with quote

Looking good!
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jdougn
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Location: Louisville KY area

PostPosted: Tue Oct 13, 2009 9:51 am    Post subject: Reply with quote

Hey Felixx, nice clean beginning to your vac former! I'm a bit jealous of the Gast pump.
DougN
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felixx
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Joined: 21 Sep 2009
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Location: San Diego, CA

PostPosted: Tue Oct 13, 2009 8:14 pm    Post subject: Reply with quote

Ok so i did some more work on the platen today.













I didnt want to close it up for a couple reasons: Wanted the flashing to dry exposed to air, and i wanted to cut the center hole on the bottom first.

Which drives me to my next query.

I wondered around home depot looking at all the different pipe fittings and materials and costs but before i did all that I was hoping to get a suggestion or two. I want to bore a hole on the table top obviously and then a hole on the bottom of the platen.

Scott:
You mentioned something about shellac. After I cut my gasket, i put my lips up and gave it a kiss and sure enough, with enough suction, you can pull some air. But I plan on sealing that. The gasket fit really well, i put a nice bead along it and then tacked it in four places with nails with the heads cut off.

I also counter bored the holes that i plan on squeezing this whole thing together.

Sheet metal is next as well. So any pluming suggestions i am open to. I appreciate your comments so far.

cheers
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trapperdale
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Joined: 07 Jun 2009
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Location: fresno, california

PostPosted: Wed Oct 14, 2009 1:01 am    Post subject: Reply with quote

you are doing a great job!
but Scott is right about the shellac !!!

i like you skipped the shellac and my unit leaked badly!! ( would not pull a tight part)
after the shellac i had to install a bleeder valve to release my finished parts from the platen. now i am running two hundred parts a week with no problems. Do it now before you have to rework your machine.
shellac it inside and out just not the top.
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felixx
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Joined: 21 Sep 2009
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Location: San Diego, CA

PostPosted: Wed Oct 14, 2009 1:36 am    Post subject: Reply with quote

trapperdale wrote:
you are doing a great job!
but Scott is right about the shellac !!!

i like you skipped the shellac and my unit leaked badly!! ( would not pull a tight part)
after the shellac i had to install a bleeder valve to release my finished parts from the platen. now i am running two hundred parts a week with no problems. Do it now before you have to rework your machine.
shellac it inside and out just not the top.


can you be more specific where to shellac? any particular brand?

thanks for the tip, im sure i will be thanking you big time!

Still need to figure out my plumbing before i close it up though
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spektr
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PostPosted: Wed Oct 14, 2009 8:34 am    Post subject: sealing. Reply with quote

Vacuum is a lot more critical than pressure with regards to leaks.
It is vital that leakage be at a bare minimum.
When you sucked on the MDF, what you probably didnt know is that you weren't pulling hardly any vacuum at all and you could flow significant amounts of air thru the "solid" board.

Sealing is critical to good performance unless you have a pump that can exceed the leak losses, and in most cases, home machine guys don't.
I'm not sure youre new pump is there either. I have a vane pump on 220 3 phase, and some of my older 2 x 4 foot molds leaked so bad, I lost a part the first time I used them a while bacl. I resealed the tools and the problems vanished..

I use 3 things to seal my stuff, Shellac, Silicone Caulking and mastic style weatherstripping.

Shellac is cheap and a quart go's a long way. Buy freah because it is an organic coating and after it ages too long it will never harden. It is also soluable in alcohol, so after you use it, watch the solvent clean ups.

The idea is to put a few coats of shellac on the inside of the platen parts before you assemble it. As you assemble it, use a good wood glue to fill in the gaps. After you have the platen screwed together, shellac the outsides of it anywhere the plastic will not contact it. It will melt onto plastic if you put it on the wrong surfaces. Not fatal, but quite messy.

After you have the platen sealed, my favorite method of hooking it up is to use plumbing floor flanges and pipe threaded nipples.

To do this, bore a hole in the bottom of the platen, bigger holes are always better. Since you used mdf, you can use wood or drywall screws to connect the floor flange to the bottom of the platen. Use silicone seal under the flange. Screw a 3 or 4 inch nipple instead of a short one onto the floor flange, Makes it easier to hook up. The outside of this joint gets mastic seal.

Now "bed" the platen assy onto the table. use LOTS of white glue to hold it in place and seal it. There is no such thing as too good a seal job,

ASK DALE IF YOU DONT BELIEVE ME.

This will get you a leak free platen.


Back to the sidelines.......

Scott
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jdougn
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Joined: 18 Mar 2009
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PostPosted: Wed Oct 14, 2009 3:08 pm    Post subject: plumbing flanges work Reply with quote

Scott & Dale both know their stuff. Seal the MDF surfaces well except for anything coming in contact with the plastic. Use galvanized plumbing flanges for your vac hook up and use silicone caulk under the flange. My system actually uses 1.5" flanges with quick disconnects on flexible 1.5" vac hose. This makes switching vac lines on production plantens a breeze.

This might be helpful, use Thompsons paste wax anywhere that you don't want silicone caulk to permanently bond. Seal the planten with shellac first then apply Thompsons on the planten under the flange so the flange can be removed later on. I also use wax around the perimeter of my production plantens so they can be disassembled to change the mold. Thompsons is important since the silicone caulk will still cure properly. The silicone caulk wont cure when using most other brands of wax.

hth, DougN
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felixx
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Joined: 21 Sep 2009
Posts: 68
Location: San Diego, CA

PostPosted: Fri Oct 16, 2009 5:55 pm    Post subject: Reply with quote

Im having fun with Shellac and silicone. Ill have some pics up in a bit. needs to dry before I assemble. I took some valuable advice and went with TWO 1 inch flanges for the platen.

like i said, more to come Smile
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felixx
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Joined: 21 Sep 2009
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Location: San Diego, CA

PostPosted: Fri Oct 16, 2009 9:32 pm    Post subject: Reply with quote

Ok, today was a busy day. First went and got some supplies.



I had never worked with Shellac before, was interesting to say the least Smile

A friend of mine had a bunch of extra 3/32 aluminum so I grabbed a sheet (free is always good!) just need to cut it down to size



Started to cut the holes out for the flanges. As stated before, I went with two instead of the one. I got to thinking among other things, it would be less stress on the platen itself. These are 1 inch with a 4 inch nipple.



wanted to make sure there was a good seal so i went heavy with the silicone.




started with the shellac



after 3 coats, a nice bead of silicone along the gasket and im ready to assemble





Done for the day. I ended up using double the amount of screws to hold it together. 56 screws, I wanted to make sure there was a tight seal. I also added silicone around the base of the nipples and along the sides of the platen.

I will finish with the shellac on the sides and the bottom this weekend. I want to give enough time to cure. I tell you what though, I put my hand on one nipple and gave a kiss to the other and sucked a little, shes tight!

Yes im still talking about my Platen, lol

anyway I am pretty proud of myself and my work. Im careful not to rush.

As far as mounting the platen to the table, I have already cut the two holes for the flanges. I know Scott mentioned using silicone? What about screwing from the bottom? Any more suggestions on this?

thanks
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spektr
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PostPosted: Sat Oct 17, 2009 8:04 am    Post subject: Reply with quote

Felix.. The reaon I told the last guy to bed it in silicone as to prevent leaks. Nacuum is also sentitive to the DIRECTION of the leak. You want to seal at a minimum the OUTSIDE of the thing being sucked on. In other words, the vacuum will be pulling the finish INTO the surface, not awway from it. Probably more critical with silicone, but still a good idea.

Screwing the platen to the table will be fine if you can do it without creating a leak path. An unknown in a blind assy. You do need to shellac the outsude surfaces of the platen well before doing anything.

Thinking about it for a minute, Why dont you get a couple LONG countersunk screws, drill thru the top of the platen so they stick out the bottom, make holes in the table and bolt it up. If you seal it well it will let you make interchangable platens for down the road when you get tired of not using the perfect sized piece of plastic. it will also adapt the base to accept dedicated mold bases later....

Scott.
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jdougn
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PostPosted: Sat Oct 17, 2009 8:07 am    Post subject: mounting the planten to the table Reply with quote

Hey Felixx, your idea to mount the planten to the table from the bottom with screws is a workable idea. This also allows for easy planten changes if they're needed in the future. You're doing a good job of keeping everything sealed as you go so keep up the good work! Nice score on the 3/32 aluminum too!

DougN
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felixx
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Joined: 21 Sep 2009
Posts: 68
Location: San Diego, CA

PostPosted: Tue Oct 20, 2009 11:46 pm    Post subject: Reply with quote

Today I went to the hanger (moms husband builds planes) and made some plates for casters



I also cut my sheet metal for fit. However I am going to need to aquire some clamps to hold everything together while i bend the sheet metal



Check out the shellac and seal job on that bad boy!

I also bought some aluminum foil tape (seven bucks for a roll ill barely use!) for after i bend the metal and tack it in with some panel nails i got today too.

I grabbed a couple extra 1/8 drill bits for the drilling on the platen when im ready.

I can feel myself getting close this is great!

After im done with the platen, I can either start with the plumbing (which im still trying to figure out) or work on the frame that will hold the plastic.

Any plumbing tips would be appreciated.
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