 |
www.TK560.com
Vacuum Forming, Movie Prop, Sci-fi and GIjOE Forum
|
|
|
| View previous topic :: View next topic |
| Author |
Message |
Israel franco
Novice
Joined: 22 Sep 2005
Posts: 51
Location: mexico d.f.
|
 Posted: Thu Mar 25, 2010 3:31 pm Post subject: |
 |
|
thanks for the feed back friends  i already re-make all the plumbing whit 1" pipes
these are exactly what i got now ( i have a 3/4 vlave i leave this valve because in the store did not have in stock 1" valve  as soon as I can get i will change for a 1" valve
doug you were right, the hoses did not work, when i do the test, the hoses collapsed, so i change it for PVC pipe (hydraulic)
| stormtrooperguy wrote: | using 1/2" at the platen seems like it could be a problem. that's the spot where you'd want the most air rushing through. cutting your pipe in 1/2 there doesn't sound right.
is there any way you can replace the 1/2" connection on the platen with 1"? |
hi i stormtrooperguy in my old table i was made the 1/2 platen (always work fine to me) at first, i thought to use it like that to test, plus I thought it would be difficult to modify (anyway the new platen will be with 1 "hole so I think was no necessary to change it) but then I saw that it wasnt so complicated to change, so following your advice I made the modification improved 
| spektr wrote: | | this will probably be ok for thin stuff, but I think you will be hard pressed to move a lot of air fast enough to do thicker faster setting plastic. I suggest using as much large diameter stuff you can, and for gods sake, get rid of the small bore quick disconnects. Remember pressure and vacuum are very different in flow. Vacuum is much more sensitive to the wrong cross sections and obstructions. |
thanks for your answer spektr, You are right, definitely, I put aside the idea of quick connectors, i will have to think another way to use different size platens
do you believe the hose connection of 3/8 from the vacuum pump to the plumbing (according to the diagram that I post) affect performance??
thank you all for your advice, now I like to do a real test, but still can not get the vacuum gauge, do you believe could i make the test without the vacuum gauge?
meantime i will continue with the construction of the new top-oven  |
|
| Back to top |
|
 |
jdougn
Guru
Joined: 18 Mar 2009
Posts: 714
Location: Louisville KY area
|
| Posted: Thu Mar 25, 2010 6:31 pm Post subject: |
|
|
Good progress & the picts are great!
_________________
DougN - Just in case you're wondering, I got my "rating" legitimately... by posting aimless drivel, useless advice, and pointless questions. |
|
| Back to top |
|
|
Israel franco
Novice
Joined: 22 Sep 2005
Posts: 51
Location: mexico d.f.
|
| Posted: Mon Mar 29, 2010 4:53 pm Post subject: |
|
|
thanks more pics are coming soon
now I have decided to continue with the new platen
1.- as I have a multi-hole platem, I wiil make the single hole design but have some questions:
is necessary to use the sandwich? or just i have to make the middle hole and connected directly to the plumbing?
2.-can i use only MDF or i have to use a aluminium sheet?
3.- if i have tu use aluminium, what is the best thickness?
3.- If i use only MDF, I have to apply shellac to the MDF too?
thanks!!! |
|
| Back to top |
|
|
jdougn
Guru
Joined: 18 Mar 2009
Posts: 714
Location: Louisville KY area
|
| Posted: Tue Mar 30, 2010 7:23 am Post subject: |
|
|
Hey Israel,
MDF will not work as the primary surface for a platen. MDF is very porous and seems impossible to properly seal.
Look at page 4 of the linked thread for information on how to build a general use platen.
http://www.tk560.com/phpBB2/viewtopic.php?t=1162&postdays=0&postorder=asc&start=45
If you notice, the top sheet is aluminum with 1/16" holes, then hardware cloth, (also called rat wire or heavy screening), then another sheet of aluminum with only the hole/s necessary to allow for the main vacuum connection. All of this is mounted on MDF board. The plumbing connection is actually screwed into the MDF also. As shown in the picts, use plenty of 100% silicone caulk since it stays flexible and will handle the high heat of a vac former.
The hardware cloth creates an air space for the vacuum to flow to all of the tiny holes in the top sheet. The aluminum sheet on the bottom is the air seal. The MDF simply supports the assembly, it provides no air seal.
hth, DougN
_________________
DougN - Just in case you're wondering, I got my "rating" legitimately... by posting aimless drivel, useless advice, and pointless questions. |
|
| Back to top |
|
|
stormtrooperguy
Expert
Joined: 24 Sep 2009
Posts: 126
|
| Posted: Tue Mar 30, 2010 9:26 am Post subject: |
|
|
I used plywood on mine and it seems to be holding up.
I did 1 sheet of 1/2" ply, a 1/8" spacer, then another sheet of 1/2" ply.
I painted the inside of the plywood with shellac, and then the outside of the bottom and edges. Basically, the outside top is the only layer I did NOT shellac.
I sealed the edges with silicone sealer.
At some point I'll probably make a metal covered one, but for now the wood is fine. |
|
| Back to top |
|
|
jdougn
Guru
Joined: 18 Mar 2009
Posts: 714
Location: Louisville KY area
|
| Posted: Tue Mar 30, 2010 7:05 pm Post subject: |
|
|
| stormtrooperguy wrote: | I used plywood on mine and it seems to be holding up.
I did 1 sheet of 1/2" ply, a 1/8" spacer, then another sheet of 1/2" ply.
I painted the inside of the plywood with shellac, and then the outside of the bottom and edges. Basically, the outside top is the only layer I did NOT shellac.
I sealed the edges with silicone sealer.
At some point I'll probably make a metal covered one, but for now the wood is fine. |
Spektr told me about the wood platens. Most of my molds are premanently fixed to the platens that are made out of 3/4" cabinet plywood. They are all sealed the same way you describe. I really like that you can force the plastic off the mold after forming. No more trying to pry a loose mold out of the plastic. Just a quick up-lift on the carrier frame and everything pops loose!
Some people feel that the plywood can't be sealed real well but I've not had a problem either.
_________________
DougN - Just in case you're wondering, I got my "rating" legitimately... by posting aimless drivel, useless advice, and pointless questions. |
|
| Back to top |
|
|
Israel franco
Novice
Joined: 22 Sep 2005
Posts: 51
Location: mexico d.f.
|
| Posted: Tue Mar 30, 2010 8:36 pm Post subject: |
|
|
i think i go for mdf platen for now like stormtrooperguy sealing all, because MDF are more easy to get than alumimium
with my old platen (is a MDF multi-hole platen cover for a sheet of metal, made like the number 2 in the draw) i was make some good pulls using a shop vac (btw i dont seal that platen  ), but now i want to experiment with the single-hole desing but i dont know if is necesary make the "sandwich" I guess the empty space left inside the "sandwich" is used to distribute the air flow in all holes, but in a single hole, this job would make the hardware cloth.. I'm right or that "box chamber" serves to increase performance in some way?
on the other hand i change the 3/4 valve for a 1" valve also i got a gauge, but it is a gauge to measure other things not for vacuum only (is for air conditioning units) , the range of measurement is very small, but is the only one I could get
I did a test and I only get 20inhg (i dont know exactly the number because the very small measures, can be 21inhg or 19inhg ) but the needle stops near the 20inhg in about 40 sec. and not more, no matter how long the pump are running..... these is normal?? ......or maybe the vacuum gauge does not work very well... Tomorrow I will the first real test (Wish me luck ) and will inform you of the results
Also I got a large propane tank, I thought used by connecting to another tank if the test of tomorrow will not achieve the desired results
here a pic of the vac-table with the vacuum gauge and 1" valve i also paint the base, green is not my favorite color but is the color i already have 
 |
|
| Back to top |
|
|
spektr
Master
Joined: 07 Jan 2008
Posts: 425
|
| Posted: Wed Mar 31, 2010 7:56 am Post subject: |
|
|
| it sounds like you have leaks. Seal the outside of all joints with something like silicone seal or latex house calking. pressure checks will not necessarily show ouu all the leaks, so i stopped messing around and seal everything liberally. Scott. |
|
| Back to top |
|
|
stormtrooperguy
Expert
Joined: 24 Sep 2009
Posts: 126
|
| Posted: Wed Mar 31, 2010 1:03 pm Post subject: |
|
|
| Israel franco wrote: | i think i go for mdf platen for now like stormtrooperguy sealing all, because MDF are more easy to get than alumimium
|
MDF and plywood are very different structurally... I don't know if MDF would work as well. |
|
| Back to top |
|
|
jdougn
Guru
Joined: 18 Mar 2009
Posts: 714
Location: Louisville KY area
|
| Posted: Wed Mar 31, 2010 9:26 pm Post subject: |
|
|
| Israel franco wrote: | ... I guess the empty space left inside the "sandwich" is used to distribute the air flow in all holes, but in a single hole, this job would make the hardware cloth.. I'm right or that "box chamber" serves to increase performance in some way?
Also I got a large propane tank, I thought used by connecting to another tank if the test of tomorrow will not achieve the desired results
here a pic of the vac-table with the vacuum gauge and 1" valve i also paint the base, green is not my favorite color but is the color i already have |
The "box chamber" does exactly what you said. It distributes the air flow. However, keep it as small as reasonable. The larger that space is the more vacuum you will lose.
The propane tank will work great. However, don't connect it to your system until you seal all existing leaks. It will be easier to find any new leaks if the existing system is already sealed properly. Then, when the propane tank is connected if there are any leaks they will all be on the new plumbing for the tank. Using the tank will increase the cubic feet of vacuum capacity. The tank will not increase the inHg of vacuum.
What does the needle on the gauge do when the valve is closed and the pump is turned off? The needle should stay in the same place for a long time without moving. If the needle moves very much that means there are leaks. As Scott said, seal every joint in the plumbing.
The base looks good even though it is green...lol.
_________________
DougN - Just in case you're wondering, I got my "rating" legitimately... by posting aimless drivel, useless advice, and pointless questions. |
|
| Back to top |
|
|
Israel franco
Novice
Joined: 22 Sep 2005
Posts: 51
Location: mexico d.f.
|
| Posted: Thu Apr 01, 2010 2:39 pm Post subject: |
|
|
| spektr wrote: | | it sounds like you have leaks. Seal the outside of all joints with something like silicone seal or latex house calking. pressure checks will not necessarily show ouu all the leaks, so i stopped messing around and seal everything liberally. Scott. |
thanks scott, I also think that there are some leak somewhere between the pump and the "suction surface", since all the connections going from the pump to the tank are sealed with silicone, I have not yet sealed the connections from the pump to the platen because the platen I'm using now, is tentative, after the new platen was done, immediately i will seal all
| stormtrooperguy wrote: | | MDF and plywood are very different structurally... I don't know if MDF would work as well. |
hi stormtrooperguy, Yesterday I made a real test with my old platen and apparently the MDF works well (although this platen is not sealed) I hope with the seal of shellac improve performance
| jdougn wrote: | | The propane tank will work great. However, don't connect it to your system until you seal all existing leaks. It will be easier to find any new leaks if the existing system is already sealed properly. Then, when the propane tank is connected if there are any leaks they will all be on the new plumbing for the tank. Using the tank will increase the cubic feet of vacuum capacity. The tank will not increase the inHg of vacuum. |
doug you are right, I think connecting the propane tank, until I finish everything else, and make sure all leaks are gone
| jdougn wrote: | | What does the needle on the gauge do when the valve is closed and the pump is turned off? The needle should stay in the same place for a long time without moving. If the needle moves very much that means there are leaks. As Scott said, seal every joint in the plumbing. |
when I turn off the pump and close the valve, the needle stays in the same place, does not move upward or downward, only when i open the valve the needle moves very quickly toward zero
Yesterday's test was successful but not entirely satisfactory, the results using the vacuum pump were almost the same that i was obtain using the shop vac (i was use styrene .60 and 100 for the test)
the most noticeable difference was that the plastic down much more rapidly, but once I closed the tank valve, the plastic rose again causing a loss in the details.
the first pull, it was too fast, however, not strong enough to let rthe plastic penetrate into all the details especially in places where space is small
I think 3 things:
1.- the pump by itself does not have the strength to hold the plastic in place (addition, leakage that may have the plumbing to the platen)
2.- the tank is to small and fills before removing completely the air between the mold and platen
3.- there is much loss of vacuum in the connections that go from the pump to the platen or maybe the seal between the holding frame and the platen is not good enough to maintain the vacuum
the pics:
 |
|
| Back to top |
|
|
stormtrooperguy
Expert
Joined: 24 Sep 2009
Posts: 126
|
| Posted: Thu Apr 01, 2010 3:26 pm Post subject: |
|
|
If your vacuum is down to 0 before the plastic cools, you'll definitely have problems. The plastic should make a near-perfect seal, preventing air from getting in.
I've got a couple of leaks still in my system, but I'm aware of them and they are slow (the pipe unions are unsealed since I'm still moving things around a bit) |
|
| Back to top |
|
|
Israel franco
Novice
Joined: 22 Sep 2005
Posts: 51
Location: mexico d.f.
|
| Posted: Thu Apr 01, 2010 3:49 pm Post subject: |
|
|
yes stormtrooperguy the vacuum down to 0 in the first second than i open the valve thats is why i'm think the tank is too small for the amount of air between the platen and mold, also im sure the holding frame are not making a good seal between the plastic and platen......i have to solve this problem
i already seal all the pipes unions from the pump to tank, but from the pump to the platen are still unsealed for the same reason, I'll be making moves until the new platen are ready
once I have all the new parts of the machine installed in a fixed location i will put tons of silicon everywhere ha ha ha!!! |
|
| Back to top |
|
|
|
|
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
|
Powered by phpBB © 2001, 2005 phpBB Group
|
Log in to check your private messages
Log in
Register
