Vacuforming Questions

Discussion in 'General Modeling' started by Flintlock, Dec 1, 2011.

  1. Flintlock

    Flintlock Sr Member

    Trophy Points:
    1,241
    Even though I've been involved in researching SS kit donor parts since '97 or '98, I'm really not that experienced in scratchbuilding. I wanted to know some things about vacuforming.

    I've never vacuformed before, and I live in a very small studio apartment. What should I watch out for so I don't let the plastic melt down onto the heating element in my stove and start a fire? :lol After I do it a couple of times I should have enough of a hang of it to do it more. But I don't want to screw it up the first couple of times.

    Has anyone tried to vacuform plastruct gray ABS sheet? How's it work out? From what I've seen it's very, very nice for scratchbuilding. But I suppose Styrene is a bit cheaper.

    I've learned that the size of the Plastruct hemisphere for the SS TIE Fighter is 5 1/4". Before I thought it was 5" and was hoping to pick up some 2.5" hemis to make a 1:48 TIE. Then I was disappointed, but then I found some 2 5/8" hemispheres (right size for studio half-scale). These hemis are made out of 'virgin' High-Impact Polystyrene, and are really nice for this project. But I need to vacuform over this shape to build the rest of the ship.

    Is this possible? Will the heat from the softened sheet warp the hemisphere? Again, it's 2 5/8" diameter and about 1/16" thick.

    By the way. The fact that the SS TIE hemi is 5.25" in diameter has some interesting consequences. The Fine Molds TIE marked as 1:72 is too small. It's about 1:100, and the "1:48" I would imagine is still too small. The ERTL Darth Vader TIE Fighter (whose wings and front window frame are used on the SS TIE Bomber) is 1:48, almost exactly - half studio scale. Which would make the TIE Bomber also 1:48, and would make this kit roughly in-scale with the ERTL X Wing. The AMT TIE Fighter double-pack and TIE Interceptor kits are also too small for 1:48. Those kits and the 1:48 TIE from Fine Molds (probably) are about 1:72.

    Anyway, any help, advice, vacuforming wisdom would be appreciated. Thanks!
     
  2. Dung0beetle

    Dung0beetle Well-Known Member

    Trophy Points:
    556
    I don't believe it to be an issue because the hot styrene will cool very quickly. Your oven needs to be about 200° - 25O° F (120° C). Use a thermometer, don't trust the oven knob. I don't have much experience vac-forming items that small, but you can start with a lower temp and gradually increase the temp. until the material begins to deform.

    I don't recommend heating plastics indoors, because they tend to give off toxic fumes. As long as you stay under about 400°, the fumes shouldn't be much of a factor.

    I hope someone more experienced will chime in and lend more expert advice. Good luck with your build.
     
  3. Flintlock

    Flintlock Sr Member

    Trophy Points:
    1,241
    Thanks for the tips. There's no way I should need to get up to 400 degrees right?
     
  4. 3d-builder

    3d-builder Sr Member

    Trophy Points:
    1,355
    Sent you a PM!
     
  5. 3d-builder

    3d-builder Sr Member

    Trophy Points:
    1,355
    You better get know where near 400 deg:behave

    :lol:thumbsup
     
  6. 3d-builder

    3d-builder Sr Member

    Trophy Points:
    1,355
    Tip..... your riser doesn't have to be that high i used
    that because I had it.

    [​IMG]
     
  7. 3d-builder

    3d-builder Sr Member

    Trophy Points:
    1,355
    Here is the video about temp.....
    [​IMG]
     
  8. Flintlock

    Flintlock Sr Member

    Trophy Points:
    1,241
    Great! Thanks! (y)thumbsup:thumbsup
     
  9. Flintlock

    Flintlock Sr Member

    Trophy Points:
    1,241
    Oh I had a few more questions.

    What's the thinnest sheet you've been able to vac form with? Have you used any Plastruct ABS instead of styrene, and is it pretty much the same deal? Is there any significant change to the thickness of the sheet when it is formed over the buck?
     
  10. 3d-builder

    3d-builder Sr Member

    Trophy Points:
    1,355
    There will be more change in thickness the taller the
    pattern is ......I don't think you will have to much considering
    the part your forming is basically half of a small globe and pretty
    small. Form in the desired thickness you want and just see what you have
    thickness wise when your done. If you feel you want it a bit thicker then
    move up in thickness.
    I don't think you need to form something like that in ABS the material
    will be more expensive, the high impact polystyrene will be fine.Remember I by my sheets in 4X8 size, so maybe a small sheet from plastruct is very affordable I wouldn't know? If you think your going to do more forming in the future better to get a half or full sheet from a plastic distributor.
    I use many thicknesses it doesn't matter you can form with paper thin,
    but it has to SUIT YOUR NEEDS. The thinner the plastic the less time it needs to heat in the oven.
    It will heat faster and cool even quicker, so it's important to have a quick smooth delivery to
    the platen.


    Regards,
    Michael
     
    Last edited: Dec 2, 2011
  11. yuumi2891103

    yuumi2891103 Sr Member

    Trophy Points:
    1,990
    You are very lucky man Flintlock-san

    Because you got the advice of Master modeler Michael 3d-builder aka Professor Vacuum forming :thumbsup
     
  12. cavx

    cavx Master Member RPF PREMIUM MEMBER

    Trophy Points:
    4,196
    I didn't want to start a new thread given I have related questions.

    I watched the Vac Forming video by Aram Batholl and he uses what appears to be a hand vacuum pump.

    It looks like a bike pump, except it sucks not blows. Are these any good? If so, where would I get one?

    [​IMG]

    In the video, he heats his plastic over the mold until it slumps, them makes the vacuum pull. Also his molds are negatives [hollowed out].

    [​IMG]

    Is there any benefit over positives for this? Or is he doing this because the vacuum of his hand pump is not that great?
     
  13. cavx

    cavx Master Member RPF PREMIUM MEMBER

    Trophy Points:
    4,196
    Another dumb question:

    Can you Vac Form over a Vac Form?

    I am guessing that if I Vac Form my part, trim it, but leave on the buck that I can pull another, now slightly larger version over the top. Is there any issues in doing this?

    I am not concerned about loss of detail as there is none on the part anyway.
     
  14. cavx

    cavx Master Member RPF PREMIUM MEMBER

    Trophy Points:
    4,196
    Another dumb question: Is there a way to work out how thin the plastic will become after Vacuum Forming? I get the more it has to stretch, the thinner it will be.
     
  15. Thranduil

    Thranduil New Member

    Trophy Points:
    2
    Generally speaking, as long as your piece is sized correctly, you should lose about half your starting thickness. The stretch causes most of this. The higher your platen (or depth if you prefer) and the smaller your framed plastic will result in thinner final.
    If maintaining your thickness is critical, make sure you have a large piece of plastic. Too large and you'll get wrinkles (creases) along the sides. This is why some platens need to be built up with what is commonly termed "run off", so the part itself comes out correct and the wrinkles end up on the run off area instead.
    I don't know if I've made this understandable, it's hard to express what really needs to be seen to be understood.
     
  16. cavx

    cavx Master Member RPF PREMIUM MEMBER

    Trophy Points:
    4,196
    Thank you for answering the question.

    The material becoming thinner makes perfect sense to me because there is a finite amount that is made to spread out further. It has to become thinner to cover the new, larger area. I guess some of this will be trial and error.

    Would these wrinkles be the same as 'webs' that can occur between parts? I have seen where they lay coins or similar thin spacers to lift the buck off the Vac Form to allow the plastic to pull down past the buck and give a cleaner sharper edge - or more to the point, allow the radius that forms to be below the buck. No problems there.
     
  17. 3d-builder

    3d-builder Sr Member

    Trophy Points:
    1,355
    Yup well said.....:thumbsup
     
  18. 3d-builder

    3d-builder Sr Member

    Trophy Points:
    1,355
    This is a part I formed recently I formed it out of .093 just a hair under
    3mm. My riser raised it 6mm off the platen, after forming the sides on the
    formed part were a hair under 2mm.

    [​IMG]

    [​IMG]

    Notice I taped off some of the holes on the platen....
    to get a more centralized vacuum around the part.
    Because the part has a lot of angels and drops,
    and I don't have a secondary vacuum source like
    a vacuum pump. I am trying to get the most draw
    I can when the plastic hits the platen.

    If I was using a thinner plastic i could expect
    sharper lines on all those angles......but it's a
    trade off, I also need enough meat left over to scribe
    panel lines. The extra meat allows me to do that and
    then just sand the angles sharp later on.
     
    Last edited: Jun 19, 2012
  19. 3d-builder

    3d-builder Sr Member

    Trophy Points:
    1,355

    Done it plenty times never had a problem.....
    yea you will increase the size as you said.

    When you start forming different shapes you
    will learn a lot....you will begin to understand
    the limitations of the process........well at least the
    limitations at home! LOL The better you can set up
    your rig the more you can expect. But you can still
    do a lot and achieve nice results at home without
    spending a mortgage payment.
     
    Last edited: Jun 19, 2012
  20. cavx

    cavx Master Member RPF PREMIUM MEMBER

    Trophy Points:
    4,196
    Awesome! I am so looking forward to my first Vac Form.

    I did a suction test yesterday because I was having a doubt that the VAX Vacuum cleaner I want to use would have enough grunt. There is no sealing tape currently on my platen so I just laid a piece of 16mm MDF that just covered all the holes, turned on the suction and once the VAX went into overload, I could not pull up the sheet. In fact the whole platen lifted off the bench. I also sourced a proper 32mm vacuum fitting for this rig rather than just drilling a hole.

    I found a heater that I think will work well. I just need to get down to the sheet metal fabricators to get some Gal to line the insides of the heating unit. I could use foil as James [XRobots] does on his video.

    What should I be paying for a sheet of HIPS? One quote came back at $70 for 2400 x 1200 sheet of 2mm. Is that right or am I being taken for a ride here?

    Oh and here is my rig. Any suggestions as to what I may have missed are welcome.

    [​IMG]

    And with my first MDF buck [my acoustic tile]

    [​IMG]
     
  21. 3d-builder

    3d-builder Sr Member

    Trophy Points:
    1,355
    Price will depend on thickness of the sheet.......I don't think you mentioned?

    Is that the frame work that will hold you plastic sitting around the platen?

    If so it's to high the equator of the frame work has to be right at the top surface of the platen or your plastic will not touch down and create the vacuum.

    If it's not disregard it just looked like it was thats why I was asking.

    Also no matter the thickness prices are different from one area to
    another.
     
  22. cavx

    cavx Master Member RPF PREMIUM MEMBER

    Trophy Points:
    4,196
    2mm is what I asked for. I will probably also be after 3.5 or 4mm. Obviously the price goes up the thicker it is. I'll continue shopping.

    I've essentally copied everything James [XRobots] does in his video. If I need to drop a layer and attach the plastic with clamps, I'll do that. Please take a look at his video and let me know if I have this wrong.

    [​IMG]

    In this image, his frame looks to be 2 pieces of 16mm MDF which is what I based mine on. I intend to counter sink the bolts at the bottom so they don't add to the height. He also has rubber or foam seals around the platen, so I guess I will need to add those as well. His system seems to work well and I figured why re-invent the wheel?

    Why is it when I pause a video to take a screen grab, I always seem to get the frame with the worst facial expression. Sorry James :$

    X ROBOTS
     
    Last edited: Jun 20, 2012
  23. JohnLogan

    JohnLogan Well-Known Member

    Trophy Points:
    510
    Do you have any small holes between your pyrmids? If not, you may wish to add them.
    They will help to evacuate the trapped air in the middle of your mold. Just a thought.
     
  24. cavx

    cavx Master Member RPF PREMIUM MEMBER

    Trophy Points:
    4,196
    Yes they are there but very small. The company that did the initial Vac Form for me drilled the holes but they also use a proper vacuum pump. Based on how well it pulled (and some parts could have been better for $85) I am thinking of re-drilling their holes larger to get that sharper detail out of each pull.
     
  25. 3d-builder

    3d-builder Sr Member

    Trophy Points:
    1,355
    Oh ok my platen is raised on my rig.......that's the difference......
    yours is not? Cool looking forward to your first attempt!:thumbsup
     
  26. cavx

    cavx Master Member RPF PREMIUM MEMBER

    Trophy Points:
    4,196
    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.

    [​IMG]

    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.
     
  27. SChristides

    SChristides New Member

    Trophy Points:
    16
    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
     
  28. cavx

    cavx Master Member RPF PREMIUM MEMBER

    Trophy Points:
    4,196
    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.
     
  29. SChristides

    SChristides New Member

    Trophy Points:
    16
    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.
     
  30. cavx

    cavx Master Member RPF PREMIUM MEMBER

    Trophy Points:
    4,196
    Yellowpages.com.au > sheet metal fabricators + suburb is how I found my guys.

    Be sure to photograph the build. Should be interesting.

    Since I didn't actually photograph the build, here is my exploded Sketch Up plan. Feel free to use this if you want. It is all made from 16mm MDF and the boarcutter I used even did the cut outs all for $35.00.

    [​IMG]

    [​IMG]
    Sorry, what is 745w about? I am not too concerned about power usage as the heating unit is only on for minutes at a time and the VAX even less. Besides I have solar and am in credit right now :)
     
    Last edited: Jun 26, 2012
  31. SChristides

    SChristides New Member

    Trophy Points:
    16
    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.
     
  32. cavx

    cavx Master Member RPF PREMIUM MEMBER

    Trophy Points:
    4,196
    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.

    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.
     
  33. cavx

    cavx Master Member RPF PREMIUM MEMBER

    Trophy Points:
    4,196
    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 :)
     
  34. SChristides

    SChristides New Member

    Trophy Points:
    16
    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...
     
  35. cavx

    cavx Master Member RPF PREMIUM MEMBER

    Trophy Points:
    4,196
    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.
     
  36. SChristides

    SChristides New Member

    Trophy Points:
    16
    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.
     
  37. cavx

    cavx Master Member RPF PREMIUM MEMBER

    Trophy Points:
    4,196
    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 :)
     
  38. cavx

    cavx Master Member RPF PREMIUM MEMBER

    Trophy Points:
    4,196
    UPDATE: After slicing my finger on the metal, the Heat Box is now done!

    [​IMG]

    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.
     
  39. SChristides

    SChristides New Member

    Trophy Points:
    16
    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 :thumbsup
     
  40. cavx

    cavx Master Member RPF PREMIUM MEMBER

    Trophy Points:
    4,196
    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.
     
  41. SChristides

    SChristides New Member

    Trophy Points:
    16
    bit like this

    Creating the original Stormtrooper - YouTube


    Just had a thought. Wouldn't having a heater enclosed in a box expose it to more heat than it would be made for and possibly melt things, like the cord? Or do you reckon the box will have enough clearance to give enough airflow to prevent that problem? I'm guess length of usage will determine the heater failing also (I don't intending on putting it through hours of usage at a time)
     
    Last edited: Jul 3, 2012
  42. cavx

    cavx Master Member RPF PREMIUM MEMBER

    Trophy Points:
    4,196
    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.
     
  43. cavx

    cavx Master Member RPF PREMIUM MEMBER

    Trophy Points:
    4,196
    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 * or other phallic symbol. I shall call this piece the "MAG in Carbinite"

    [​IMG]

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

    [​IMG]

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

    [​IMG]

    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.
     
  44. cavx

    cavx Master Member RPF PREMIUM MEMBER

    Trophy Points:
    4,196
    So yeah, a redesign on the heat box is now a must. I decided that I would have another go tonight, but the ambient air temp cooled the plastic before I could get any real suction happening. Again I had left it heat up for 45mins, and the result was pretty poor.

    So I decided to do something a little different by constructing a frame over the platen and suspending the heating element there. This proved that I need to get the plastic closer to the heat as the material was soft in 2 to 3 minutes. The challenge is that it also is much easier to burn the plastic and I did this on one section, so that is now a throw away.

    I did raise the bucks but it didn't matter too much as the plastic cooled too fast even with the garage door closed. So I have pull 3 which is better than 1 and 2, but still far from perfect.

    [​IMG]

    It is actually easier to see the detail from the inside.

    [​IMG]

    Maybe there is not enough suction here either as the detail is there on the higher parts, but it is not there at the base and both parts were slightly raised off the platen for this pull.
     
    Last edited: Jul 9, 2012
  45. tictoc

    tictoc Well-Known Member

    Trophy Points:
    746
    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.
     
  46. cavx

    cavx Master Member RPF PREMIUM MEMBER

    Trophy Points:
    4,196
    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.

    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.

    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.
     
  47. tictoc

    tictoc Well-Known Member

    Trophy Points:
    746
    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.
     
  48. cavx

    cavx Master Member RPF PREMIUM MEMBER

    Trophy Points:
    4,196
    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.
    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 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.
     
  49. tictoc

    tictoc Well-Known Member

    Trophy Points:
    746
    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.
     
  50. cavx

    cavx Master Member RPF PREMIUM MEMBER

    Trophy Points:
    4,196
    Not paranoid, but concerned about the real possibility.

    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.
     

Share This Page