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

PostPosted: Fri Oct 30, 2009 1:45 pm    Post subject: Reply with quote

lobosmedic wrote:
Eureka, success!

I'm glad it's going well for you, you could have almost formed a part out of plastic sheet and that dyson!

Is that floral foam I see, hmm, looks strikingly familiar to a TK handplate. Wouldn't be trying the Dan Laws sculpt to vac technique I linked earlier would you ... Razz Probably just made it to quick to test it, but its a great technique for making positives, you could just harden the outside, fine tune it and whala! instant mold. And i'd be happy if anyone took my vac form advise, lol.

keep up the great work


Very Happy


thanks for the kudos. To be honest the green foam was what i had laying around, i didnt realize it looked like a hand plate until after Smile

My next task will be to plum everything. Im going to wait to mount the platen to the table until I finish the frame too.

ANother hurdle for me will be the oven. The outlet I use im sure is tied into the same breaker as the washer and dryer in my garage. (i rent the garage at my apartment). I dont have the luxury of being able to re-wire anything.
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spektr
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Joined: 07 Jan 2008
Posts: 425

PostPosted: Fri Oct 30, 2009 2:35 pm    Post subject: Reply with quote

no big deal, use an appliance plug and keep the amp draw down, piece of cake... my first machine used an appliance outlet..... Scott.
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felixx
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Joined: 21 Sep 2009
Posts: 68
Location: San Diego, CA

PostPosted: Fri Oct 30, 2009 3:36 pm    Post subject: Reply with quote

spektr wrote:
no big deal, use an appliance plug and keep the amp draw down, piece of cake... my first machine used an appliance outlet..... Scott.


what kind of oven was it? can you elaborate on it? thanks!
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felixx
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Joined: 21 Sep 2009
Posts: 68
Location: San Diego, CA

PostPosted: Fri Nov 06, 2009 1:47 am    Post subject: Reply with quote

Im still alive on this project, been pretty busy with the new job and all. im still looking for a tank and as far as an oven its still up in the air...
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TK 109
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Joined: 11 May 2007
Posts: 712
Location: Galena, Ohio

PostPosted: Fri Nov 06, 2009 10:59 am    Post subject: Reply with quote

I'm looking at this again, and I like what I see. A lot! That's how I tested my first platen, as well. Only your's went better. LOL

NICE, quality work there, Felix. Nice! Very Happy
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felixx
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Joined: 21 Sep 2009
Posts: 68
Location: San Diego, CA

PostPosted: Sun Nov 08, 2009 11:34 pm    Post subject: Reply with quote

news on a possible tank find. I dont know the size of it yet, but I have noticed during my search that a lot of tanks go over 30 gallons.

If anyone can shed some light on this, with my gast 1023, at what point would it (the tank) be considered too big?

thanks for any suggestions/tips on tank size
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jdougn
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Joined: 18 Mar 2009
Posts: 714
Location: Louisville KY area

PostPosted: Mon Nov 09, 2009 9:01 am    Post subject: Reply with quote

Hey I've taken a post from CNCzone that was about degassing silicone & vacuum chambers and adapted it to our use on tanks. My edits are in italicized CAPS

ALpmc on CNCzone wrote:
I can honestly tell you you that I tried my very best to take every short-cut to avoid paying the high price of a proper vacuum pump. I tried everything and nothing worked! After I added the overall cost of my short-cut attempts together, I could have bought a nice pump.

The size of the vacuum pump is dictated by the size of the vacuum TANK and the time that is needed to achieve an adequate vacuum BEFORE THE NEXT PULL. So.........No matter what! There is no escaping MATH in order to determine the best possible vacuum pump you need for your task!

In order to calculate the total volume of any round chamber you must multiply radius x radius x height x 3.14. Same principle as estimating the volume of a round mold box.

Note that a radius is half the diameter. A 10 inch circle has a 5 inch radius and that’s why we multiply it twice.

For example, if I had a chamber measuring 8 inches around (ID) by 10.5 inches tall, this is what the math would look like:

4 x 4 x 10.5 x 3.14 = 527.52 cubic inches of air volume inside my chamber.

We must convert inches into feet now. There are 1728 cubic inches in a cubic foot. In order to convert cubic inches into cubic feet you must divide the cubic inches by 1728.

So......... 527.52 divided by 1728 = 0.30 of a cubic foot.

Now that we know our volume, lets build a foundation for calculating an adequate vacuum pump size.
We are going to use these rules:

PS = Pump Size or CFM
V = Volume
T = Vacuum time
PDF = Pump down factor. 1 Torr is 7. 10 Torr is 5.

This is our first question concerning pump size!

How long will it take for a 5 CFM vacuum pump to pull 1 Torr (1000 microns or 29.88 in-Hg) in my .30cf chamber?

Here is our formula: T = V x PDF divided by PS

What is our V? It is .30cf
What is our PDF? For 1 Torr it is 7
What is our PS? It is 5 (CFM)
.30 x 7 = 2.1 divided by 5 = .42 of a minute. That’s less than a minute to pull an adequate vacuum for degassing in a chamber of this size.

What is the minimum size vacuum pump required for achieving a 1 Torr (1000 microns or 29.88 in-Hg) vacuum level within 1 minute in my .30cf vacuum chamber?

Here is the formula: PS = V x PDF divided by T

What is our V? It is .30cf
What is our PDF? For 1 Torr it is 7
What is our T? 1 (min)
.30 x 7 = 2.1 divided by 1 = 2.1 CFM pump would pull 1 Torr of vacuum in one minute. This would be a minimum but adequate pump for degassing in a chamber of this size.

............
After many hours of searching, studying, and pricing I finally decided on a pump that was used by home air conditioning servicemen to pull vacuums on refrigerant lines in order to eliminate water condensation. It was a RobinAir VacuMaster 5 CFM SPX 15500.
...

Good luck!


My pump is 10cfm and the tank is 30 gallons. Based on the above math and on reality, it takes a little over two minutes to get over 25inHg. IMHO, the more tank you have the better your pulls will be since the vacuum will not drop as much during the first stage of the pull. I have another 20glln tank on hand that I need to get plumbed into the system and I wouldn't mind adding more tank than that. But, remember that I'm pulling 1/8"-1/4" ABS which needs a good solid vacuum maintained over a few minutes to keep the detail in the plastic. If you're pulling thinner stuff then the tank volume wouldn't matter as much. Additionally, if you have enough pump cfm then you could get by with less tank. Right now, my 10cfm pump will not keep up with the occasional edge pulling loose or vent hole blowing out. If I keep doing this the goal is to double the pump capacity and get more tanks.

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

PostPosted: Thu Nov 12, 2009 1:56 pm    Post subject: Reply with quote

Picked up a used (not working) 30 gallon water heater a couple nights ago. yesterday i got around to stripping it. getting ready for paint etc. Man there is a lot of stuff that gets put inside these things!

found a huge FAT Black Widow on the bottom of it too Shocked

Here is a pic after I started to pull off the outside cover:



All ready!


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jdougn
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Joined: 18 Mar 2009
Posts: 714
Location: Louisville KY area

PostPosted: Fri Nov 13, 2009 7:33 am    Post subject: Reply with quote

Looks like a lot of work getting that tank clean up! Were you able to get much of the crap out of the inside of the tank? The often have alot of sediment built up in side.

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

PostPosted: Fri Nov 13, 2009 11:38 pm    Post subject: Reply with quote

yes it was a lot of work, and there is still a little inside i cant seem to get out. any suggestions other than using a torch? lol
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Fredo
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Joined: 21 Mar 2007
Posts: 251
Location: Kingdom of Nye Area 51

PostPosted: Sat Nov 14, 2009 9:33 am    Post subject: Reply with quote

Tape a smaller flexable tube to the end of your vacuum cleaner hose and suck out the smaller pcs. First go over your tank lightly with a hammer to knock any loose pcs. to the bottom...........Fredo
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spektr
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Joined: 07 Jan 2008
Posts: 425

PostPosted: Sat Nov 14, 2009 11:13 am    Post subject: Reply with quote

swimming pool acid.......

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

PostPosted: Wed Nov 18, 2009 1:13 pm    Post subject: Reply with quote

Im off to the hanger today to work on the tank. gonna do some welding to it Smile
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spektr
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Joined: 07 Jan 2008
Posts: 425

PostPosted: Wed Nov 18, 2009 2:55 pm    Post subject: Why Weld on a tank? Reply with quote

DON"T weld on a tank.. If it has a hole, patch it from the outside this way. Sand the area clean, cut a piece of roof flashing that will cover the damage area with a lot of overlap. Glue the flashing to the tank with acrylic caulk or silicone seal. Aluminum furnace tape the edges, done.
It's not a presure vessel you know....

Scott.
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felixx
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Joined: 21 Sep 2009
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Location: San Diego, CA

PostPosted: Thu Nov 19, 2009 11:16 am    Post subject: Reply with quote

Well there was no need to do any welding, I simply bought a few 3/4 inch plugs and sealed them in.

I also bought fittings to plum two 3/4 inch holes to a single 1 inch (to stay consistent)



I used a union in the center but for the two platen flanges i will use a short piece of high vac hose instead. I dont want any pulling or stress on the flanges.

btw the blue stuff you see on the fittings is like plumbers dope only high grade thats used on airplanes
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