Vacuforming Questions

3d-builder said:

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Oh ok my platen is raised on my rig.......that's the difference......
yours is not? Cool looking forward to your first attempt!

Cool. So am I

Unlike James that used kitchen foil in the heating unit, I am getting a galvanized flume (if that is the right word) made for my heating unit.



I picked up a wall mountable 2 bar heater today (hope it will produce enough heat) for $15.00 [new]. I chose this unit because it was the only one without the tilt sensor [mercury switch?] which would prevent other units working on their backs. This one even has a small stand, so the unit is actually off the floor by at least 2".

I also got a quick over the phone quote where each piece of 0.6mm gal is less than $7.00 per piece cut and supplied and they can even bend the ends to 90 degree for me.

And about another $30 for the MDF box it goes in.

Where'd you get the gal from? Brisbane only store or somewhere I can find here in Perth?
I was thinking of doing the same but never bothered looking for a supplier. Didnt even check Bunnings for that matter

SChristides said:

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Where'd you get the gal from? Brisbane only store or somewhere I can find here in Perth?
I was thinking of doing the same but never bothered looking for a supplier. Didnt even check Bunnings for that matter

I am getting mine from a local sheet metal fabricator. I went to Bunnings first and they didn't even have gal sheets. They had aluminum for $30 for a 900mm x 600mm sheet. I decided I didn't want to spend that much, so looked on yellowpages.com.au for sheet metal fabricators on the south side. Phoned them up and got a quote for just under $7.00 for the same size sheet in gal.

Cheers. Might go the length to do the extra research over here then instead of settling for foil.
Be sure to photograph the build. Should be interesting.
I'm only at pen & paper at this point but once I start to build I'll document my progress.
Also, for what its worth (depending on the accuracy) I have read that its about 745w per HP.

Sorry. I'm bad for not explaining myself.

745 watts per HP for the vacuum

i.e. I've read people using a 2-3 HP vac. Thus 2 HP would be about 1500w vacuum cleaner. There abouts.

I got a 2000-2400w bar heater from Cashies except it tripped my powerboard on high which I'm assuming is running the full 2400w. I'm guess I can get away with it on medium (2000w).
Only drama is all three bars of the heater are positioned towards the bottom of the heater so I'd have to have the heater off centre in the bottom of the box to get a more even heat distribution. The other option is to remove them from the heater and rebuild them into the box. Could be a bad idea, I dunno.

SChristides said:

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Sorry. I'm bad for not explaining myself.

745 watts per HP for the vacuum

i.e. I've read people using a 2-3 HP vac. Thus 2 HP would be about 1500w vacuum cleaner. There abouts.

Got you know. I'm not sure what Kw my VAX is rated at. Based on my suction test the other day, I am pretty sure it will have enough to pull the plastic.

SChristides said:

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I got a 2000-2400w bar heater from Cashies except it tripped my powerboard on high which I'm assuming is running the full 2400w. I'm guess I can get away with it on medium (2000w).
Only drama is all three bars of the heater are positioned towards the bottom of the heater so I'd have to have the heater off centre in the bottom of the box to get a more even heat distribution. The other option is to remove them from the heater and rebuild them into the box. Could be a bad idea, I dunno.

Yeah you are going to want the heat strips centered. I've noticed that pretty much all the floor standers have their strips offset lower and I am not sure why.

If you are feeling electrically sound, then there is no reason why you can not make the unit into a custom one for the purpose. I would have if I had not found the one I did.

UPDATE: I picked up my 4 sheets of 0.55mm Gal today for total of $30.80. I've marked them out and cut them to size. Tomorrow I start the assembly

Hope the weekend has been productive for ya. I can't say the same for myself really. Work & family took over for now.

I might have to make a start on my molds instead. Too indecisive tho

Stormtrooper
Republic Commando
Senate Commando
Royal Guard


sigh...

SChristides said:

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Hope the weekend has been productive for ya. I can't say the same for myself really. Work & family took over for now.

I might have to make a start on my molds instead. Too indecisive tho

Stormtrooper
Republic Commando
Senate Commando
Royal Guard


sigh...

Not really. Other stuff came up and left no time for this. I have tomorrow off so will finish the heating unit and hopefully might even get to do a test run as the Vac Form itself is ready to go.

How will you do the Stormtrooper etc? I want to make my own armor and whilst I know I can make the bucks, not sure what to use as the best source of reference to make them. I'd most likely start with a helmet and go from there.

I'm considering sculpting them from clay. Probably clay on top of a basic pepakura model. Not a fan of sanding you see and clay isn't as smelly and messy. lounge friendly too.

For the helmet I think I'll go the pepakura - clay pour method instead of sculpting from scratch. Although for the helmet I want to try my hand at molding and casting.

How long does a wet mix plaster take to dry? Does it set to the full hardness?

I can except that sanding (and making a mess) is all part of this hobby.

A cleaner approach might be to use 123Dmake which can layer up various 3D models to be made from card board or thin (9mm) MDF. Just need to find the 3D models now

UPDATE: After slicing my finger on the metal, the Heat Box is now done!



Not the prettiest thing I have ever made and my sheet metal working skills suck as much now as they did back in high school. It should do the job though.

cavx said:

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How long does a wet mix plaster take to dry? Does it set to the full hardness?

I can except that sanding (and making a mess) is all part of this hobby.

A cleaner approach might be to use 123Dmake which can layer up various 3D models to be made from card board or thin (9mm) MDF. Just need to find the 3D models now

Awesome. That program looks handy. Definately will look into that one thanks.

And at the end of the day the table/heater don't haveto look pretty as long as they are functional. I expect mine to be as rough as guts

Do post pics then

Thinking a bit about the Stormtrooper, and I think the helmet will need to be 5 parts:

1. top cap
2. face plate/front half
3. back half
4. left ear piece
5. right ear piece

Then there are the greblies like to the black parts that fit into the chin etc.

Thanks for that link. Very cool

My heater is elevated and the power cord runs below the heating unit and it out of the box with plenty of free air around that. Only the reflective hollow and heat bars are inside the flume on my design.

I did my first few runs today. Suction seems good as I did get the dimples of the holes of the Platen on go 3. However I need to work on the heating unit as I don't think a 1.5mm piece of HIPS should really take 45min to get hot enough. I think I need to move the heating unit closer to the plastic.

The beauty is that even though I made a few stuff ups today, I was able to simply reheat the plastic and go again. It flattened out perfectly and pulled much better with more time on the heat.

Heat time 1: 8min
Heat time 2: 30min
Heat time 3: 45min and I think I could have left it on for another 5 min and it would still be OK.

No it is not a penis or other phallic symbol. I shall call this piece the "MAG in Carbinite"



Not happy with the result, it went back over the heater and after a few minutes, it began to return to its beginning.



And after about 30 mins, flat again for round 2.



I ended up redoing this it again and I think I need more height under my bucks. So I have rigged them up on a block of wood and will pull them again later on tonight.

Are you sure you have a good seal when the platen goes onto the vacuum box?

You might try lining the vacuum form table top with some rubber (closed cell) weatherstripping. The weatherstripping should line up exactly with your frame and create a tight seal. It wears out but this might be your problem.

Also, when you heat your plastic sheet, try to put a foil or flashing lined lid over it. This will help keep the top of the plastic from cooling. Also, in the beginning, you might want to flip your plastic to help heat both sides.

tictoc said:

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Are you sure you have a good seal when the platen goes onto the vacuum box?

Not sure if I am understanding your question here, but my Platen and Vacuum Box are one sealed unit. The holes in the Platen are the top panel of the Vacuum Box and I made sure to seal the whole thing when I assembled it. I've run a few vacuum tests and I can not pull up the sheet that I am testing with once the seal is made.

You might try lining the vacuum form table top with some rubber (closed cell) weatherstripping. The weatherstripping should line up exactly with your frame and create a tight seal. It wears out but this might be your problem.

I did that yesterday. I used door rubber seals that have a sticky adhesive on one side. I then re-ran my vac tests and was convinced the seal was good.

Also, when you heat your plastic sheet, try to put a foil or flashing lined lid over it. This will help keep the top of the plastic from cooling. Also, in the beginning, you might want to flip your plastic to help heat both sides.

That makes sense as I do think so much heat is lost off the top surface. I still think redesigning the heat box so that the heating elements (and I think I will need more than one for this) is maybe 4" off the plastic. It is quite a distance off now and I just don't think that my strip heater is as hot as the "patio heater" Jame of XRobots used.

What I noticed last night is that my heaters "low mode" only used one strip heat bar, so maybe a pair of these (they cost about $15.00, so not expensive to add a 2nd heater) on low side by side might give a wider heated area.

I also have some big draw slides, so might even make the heat unit inverted and slide away like many professional units do.

Last pull was cold before I had reached 50% of the Buck height, so it would not matter if I was using a Vacuum Pump for suction, the plastic would not be able to be formed as it simply was not hot enough.

Having a quick look in in regards to a comment made earlier on, I am thinking of adding a boarder out from the base of the platen/vacuum box and making new frames. This way the platen goes up and into the hot plastic as the frame is pulled down.

So far this project has cost just $100 and it almost works, so I don't mind if I need to spend more to perfect it.

Sorry for the confusion...I do mean the box and platen. I actually used some silicone to seal the inside of my vacuum box .....but it sounds like you are already on top of the troubleshooting.

As for the heat...hmmm. I love your design. It seems sound. The larger top would seem to allow it to heat more uniformly and eliminate hot spots. But you might just need more heat if the box is too tall.

My "oven" is just a rectangular box with a removable lid and no bottom. It is about 26 inches tall. It is lined with flashing just like yours. I use two little electric grills as heaters. They are 1500 watts each and just sit on the concrete floor of my garage. It takes my oven about 10 minutes to heat up nicely (with the lid on) before I start trying to form with plastic. I always use a lid over my frame and plastic when I am forming. It takes about 3 minutes for the .080 styrene to soften and sag before I can place it on the vacuum table.

tictoc said:

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Sorry for the confusion...I do mean the box and platen. I actually used some silicone to seal the inside of my vacuum box .....but it sounds like you are already on top of the troubleshooting.

Thank you. Because I made the Platen/Vac Box out of 16mm MDF, I used "Aquadere" [white wood glue] and made sure I had a good bead of it on the insides as I squashed the joins down. No different to how I would (and have) made speaker enclosures. Rather than just drill a hole for the VAX to attach, I went and bought the proper plastic part and glued that in as well.

As for the heat...hmmm. I love your design. It seems sound. The larger top would seem to allow it to heat more uniformly and eliminate hot spots. But you might just need more heat if the box is too tall.

That makes sense. I am thinking I need to reduce the height and open the angle up a bit to keep the same area at the top. Yeah, it is definitely a heat issue, but this heating box was made with the single heater only. Adding a 2nd unit will require a redesign.

My "oven" is just a rectangular box with a removable lid and no bottom. It is about 26 inches tall. It is lined with flashing just like yours. I use two little electric grills as heaters. They are 1500 watts each and just sit on the concrete floor of my garage. It takes my oven about 10 minutes to heat up nicely (with the lid on) before I start trying to form with plastic. I always use a lid over my frame and plastic when I am forming. It takes about 3 minutes for the .080 styrene to soften and sag before I can place it on the vacuum table.

My heater is 1600W on high mode. The lid is the key too I think because I am just losing heat right out the top off the surface of the plastic. What worries me though is melting, and having hot plastic drip into the heating elements and starting a fire. This is why I think I want to build the box with the heater on the top that is either slid out of flipped. A sliding design requires more space, but is safer than one that flips.

I don't really know what heating time mine heater requires. I simply started when the elements were both glowing at a stable red.

cavx said:

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My heater is 1600W on high mode. The lid is the key too I think because I am just losing heat right out the top off the surface of the plastic. What worries me though is melting, and having hot plastic drip into the heating elements and starting a fire. This is why I think I want to build the box with the heater on the top that is either slid out of flipped. A sliding design requires more space, but is safer than one that flips.

I don't really know what heating time mine heater requires. I simply started when the elements were both glowing at a stable red.

Even when you cook food in your oven you should allow the oven to preheat and give it at least 10-15 minutes to sit after it reaches temperature.

I have never had a fire (knock on wood) but that is why I put the heaters on the concrete floor. If there is a problem, the whole kitten caboodle will get shoved to the driveway.

It sounds like you are properly paranoid about fire so I don't think it will happen if you always watch your plastic. Make a log about your heating times and how long it takes the oven to heat up and stick to that.

Try a flashing lined lid before you rip things apart and let us know how it went.

tictoc said:

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Even when you cook food in your oven you should allow the oven to preheat and give it at least 10-15 minutes to sit after it reaches temperature.

I have never had a fire (knock on wood) but that is why I put the heaters on the concrete floor. If there is a problem, the whole kitten caboodle will get shoved to the driveway.

It sounds like you are properly paranoid about fire

Not paranoid, but concerned about the real possibility.

tictoc said:

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Try a flashing lined lid before you rip things apart and let us know how it went.

I will make a lid in the next days and report back.

I am also thinking about ditching the bottom layer of the two part frame. I use screws to attach the frame and plastic anyway, so looking at the results am thinking if I even need a 2nd layer. Doing this will bring the plastic closer to the platen.