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Vac-Forming (At Last !!!)

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  • Guest

    #1

    Vac-Forming (At Last !!!)

    Firstly all credits for this device and article go to the now defunct ASP Plans Service and of course Magicalia Publishing Ltd (www.magicalia.com) who now own the publishing rights.

    This was originally produced as a kit back in the late 1980's and as far as I am aware was never produced as a separate plan. I have not copied the instructions word for word but have revamped them totally, as when you look at the drawing, you will see just how simple this device is. Building one is certainly well within the capabilities of us all on here.

    Now seems like the ideal time to show you exactly what it is and the best part is, you can probably build this for about £10...!!

    All the materials are available in your local hardware store with the exception of the Vac nozzle...rob a spare one from the wife's Hoover, or if you are not feeling that brave, buy one from a suitable dealer...they are only a couple of quid at the most. (You only need a very small straight end attachment, it doesn't matter if it has the flattened end as it will still work) Any make will do as they all more or less fit any Vac....So why a Vac - Former then..??

    Well this is a very useful method of producing many items for models of all types, Scale or Sport, Plastic or R/C. How many times have you had a plastic kit model with an ill fitting part or even deformed part that cannot be sorted. I personally have had one experience many years ago of an Airfix Jaguar Kit supplied with the wrong Canopy...ie, it was not a Jaguar Canopy !! If I had this device then I could have moulded a new one easily.

    With this device all it requires is for you to make your own mould or plug - very easy to carve from Balsa and then simply use that to mould your new part. It can be used for making Canopies as already mentioned, Turrets, Cowls, Spinners, wheel spats, lightweight wheels, wheel hub covers, wing and tail fairings, control linkage outlet fairings, dummy engines and exhausts, louvered grilles, pilots, cockpit internal fittings, raised panels, machine guns, bombs...and just about anything else you can think of. This method saves time and also helps minimize build up of weight on any model.

    Have a look at the drawing & the photo’s, you will see it is basically 2 parts, one is the lower main base...a basic box shape and the other part is the removable top frame.

    This unit is more or less designed to accommodate the standard size of ABS / Lexan / Acetate plastic sheets available from most model shops.

    As a guide, the base of this unit is the same size as an A4 Sheet of paper, armed with that, you now know exactly how long the sides and ends are. The main Frame is built from 2" x ½” Ramin. A good strong hardwood which will also minimize air leakage when the unit is in use.

    The Top Frame is also made from Ramin but using 1” x ½” thickness with a removable centre bar (more on this later) The Base is Hard Plywood and you will also need a sheet of perforated pegboard for the top of the base.

    So to start, cut your hard ply base to same size as an A4 sheet of paper and then using that, measure the Sides and cut them from the Ramin, the simply measure the ends to fit in the remaining gaps.

    Before starting assembly you might find it easier to drill the hole in one of the long sides to accommodate the Vac nozzle. Use a hole saw if you have one or drill several smaller holes around the circumference of the hole you wish to cut out and then pop the wood out. Once the hole is cut, clean up with a half round file.

    The Original instructions suggest cutting the hole slightly oversize to allow for the sealant but I cut mine so the Vac Nozzle fitted in snug (Mine was a tapered nozzle) I just sealed mine in with epoxy & of course around the edges of it once it was in place.

    Easiest way is the build the base frame first ensuring that it is square and using glue (PVA is suitable for this) and nails or screws to assist for strength. Once done, glue and pin the hardwood base on (panel pins are ideal). Sand and smooth off any rough edges.

    Once that is set, you now need to turn your attention to the inside of the box, all those inside edges (where all the joins are and the base joins the frame) need to be sealed to prevent air leakage when the unit is in use. Bathroom sealant is ideal for this and can probably found in your shed/garage/workshop. If you have to buy some, you only need a small tube. Alternatively you could seal with Epoxy resin, slightly messier but it will work. Leave this to dry or set for now.

    Whilst the above is drying, you could make the top frame which is exactly the same construction as the base frame except you have a middle strip to cut out as well and there is no base board to be glued on. The top frame should be exactly the same measurements as the base frame. Once this has been glued and nailed/screwed allow this to set. (Do NOT glue or nail the Middle strip in place !!!)

    The Middle strip is for your removable bar. Once the Frame is set, Drill screw holes where this is to fit (see Drawing) You will also need to drill screw holes on the ends of the middle strip to match where it fits in the frame too.

    If you look at the drawing you will see that both the base part and the top frame have a square lip around the outside edge. This is made from 10mm square Ramin Strip and is glued and pinned on to the frame as shown the drawing. (Panel pins are ideal here) Make sure that the lip is flush square with the tops of the frames.

    Now back to the base unit........Fit and seal the Vac Nozzle in place in the hole you made....Once set you can now fit your perforated pegboard to the top of the base. This needs to be A4 size same as the base and fitted on top and within the lip that you fitted (see drawing) you will also need to make sure that all the edges around this board are all well sealed down too, so plenty of glue here and use panel pins to assist too.

    For clarity, the perforated peg board should have holes all over it evenly spaced as per the drawing (only some of the holes are shown on there, but you get the idea) The Photos will give you a better idea.

    Once done, time for the final bit to be fitted, that strip of self adhesive foam that is mentioned in the drawing. This is basically draught excluding tape again available from your local hardware store. Fit on top of the base unit around the outside of edge of the pegboard and top of the lip as per the drawing. This helps the air seal when the unit is in use.

    And Once done that is it...You now have a Vac-Former ready to use

    Ok you need your plug or mould first...If you are moulding canopies and they have frames on them, don't forget to include them on your plug / mould as these will come out nicely in the Vac Formed item.

    Having got that you need to plug in your Vac somewhere near to an oven. Fix your sheet of plastic to the top of the top frame, (this is the edge where the lip is) Use thermal resistant double sided sticky tape or drawing pins around the lip to fix the sheet down. If you are only moulding a small part and don't need the whole sheet, Fix the Middle removable bar into the top frame (before fixing the plastic sheet) and then cut the sheet to fit the area of the item to be moulded and fix one side of it to the middle frame. Blank off the other unused half of the frame using a bit of Litho Plate or Aluminum or even some hardwood, again using the sticky tape method or drawing pins if appropriate.

    Place your plug / mould the right way up onto the perforated peg board on the base unit...use double sided sticky tape or even blue tack to secure it.

    Now placed the Top half of the frame with your plastic sheet attached into an oven heated to around 350 degrees F, Gas Mark 5 or 6 should do this. The Frame should be with the plastic on top !!

    Best if you have an oven with a glass door so you can so what is going on !!!

    Place the Frame in the Oven until the plastic softens or starts to sag, when that happens, remove the frame (using oven gloves if need be) and then turn it so the plastic is now facing downwards and place over the base unit. You need to switch on the Vac as you do this, Some Vacs have a footswitch to allow this, If you have a newer upright Vac, you may need to get someone to switch it on for you.

    * A point of note here, the newer upright Vacs have a special setting for using the nozzle with hand tools, make sure that the Vac is set for that as it provides a stronger suction force so will work better for the moulding process.

    The quicker the frame is transferred from the oven the better. If you are moulding smaller parts, you can or may need to drill some holes in the pegboard around your plug / mould before you start to allow better suction around it.

    Once on the frame, the Vac will suck the softened sheet down across your plug / Mould. If need be you can also rub it down using a soft cloth, preferably lint free to avoid scratches, (Very Important if you are moulding clear canopies !!)

    Once Done, allow the sheet to cool whilst still on the frame, then remove and cut out your moulded part.

    That’s all there is to it. Have a go with a couple of test parts till you get the idea and then you can mould what you like.

    A drawing of the Actual unit is shown below as well as a couple of Photos of the real thing.

    This is a tool that will last you many years and will prove to be very useful for custom parts. Mine is at least 20 years old now and still does me proud.

    Last but not least, as a condition of allowing this article to be posted I am asked to post a link for the Scale Models plans service as follows: http://www.myhobbystore.com

    Quite a few of you have been looking for this plans service so now here they are.

    Regards…..Mark

    [ATTACH]15421.IPB[/ATTACH]

    [ATTACH]15422.IPB[/ATTACH]

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    [ATTACH]15424.IPB[/ATTACH]







  • Guest

    #2
    P.s.

    Click on the above drawing once to open and then click again and it should go bigger, if not PM me and I will e-mail you the bigger version.

    Regards......Mark.

    Comment

    • Guest

      #3
      Mark, an excellent item and a very interesting project well within our capabilities.

      Many thanks for all the time and effort you put into this posting, I never realised how easy it could be.

      Comment

      • Guest

        #4
        Thanks for the replies,

        It took a couple of weeks and 3 e-mails to the company concerned to clear the article to be posted up....3rd time lucky I got a response, so once again all credits and thanks to them for giving permission to do so.

        This really is a useful little bit of kit to have, Once you have made one, it is surprising at how many custom bits you will end up making with it as it is that easy to use....and the beauty is no mess or fumes involved, the plug/mould only needs to be finished to a smooth surface and that will suffice.

        Mine is being pressed into service again now making custom moulded wing mirrors for the Skyline you saw on my other post....(Having fitted them on my Honda NSX, They really do add to the looks of the car). I have the basic outlines done, just got to finish the mould to shape and these will come out very nicely.

        Beats a lot of other methods anyday and the good thing is once you have your plug / mould, you can make as many as you like...so if the part breaks at some stage...just mould a new one !!

        Regards.....Mark.

        Comment

        • Guest

          #5
          Very useful post , well done. I have a number of ideas for club projects with one of these. Have to get our tame joiner to sharpen his tools . Thanks.

          Comment

          • wonwinglo
            • Apr 2004
            • 5410

            #6
            Mark,I remember this item and have seen one in action at one of the IPMS meetings,it is a great bit of kit and well worth building up.

            Comment

            • Guest

              #7
              Mark,

              What guage plastic sheet are you using?

              Looking at this got me wondering about a heat source (other than the oven) and i was wondering about those radiant fires, i cannot remember the name, the kind that floor stand and give off bright light,

              Any thoughts?

              J.

              Comment

              • Guest

                #8
                Hi Jankers,

                Not quite sure what the gauge of the sheet is, I just use the standard sheets available from the Model shops. Some of it is more or less same thickness as r/c car bodyshells although you could use thinner sheets for smaller parts.

                It is usually clear sheet sometimes clear tinted but that will work just as well, Thin plasticard if you can get the right sheet sizes should also work but I must admit I have yet to try this. (It melts well when you put something hot on it so it should mould)

                Too thick a sheet would probably take too long to soften and may not mould as well.

                As for you suggestion for the alternative heat source, yes it can be done using that as well, just make sure you have the unit plugged in nearby so you can transfer the soften sheet on the frame onto the base unit as quick as possible.

                Don't hold too close to the electric bars though as you will end up with nice big holes in your sheet !!

                Regards.......Mark.

                Comment

                • Guest

                  #9
                  Thanks mark,

                  If i remember correctly, 20 thou sheet was about the maximum considered feasible. as it happens, i visited father today and he ha one of those radiant heaters so i checked the output with my hand.

                  I believe you can get the 'elements' so was considering a built in 'hinged' design.

                  Has anyone seen anything like this (it must be 20 years since i last looked at this)

                  J.

                  Comment

                  • Guest

                    #10
                    Chers Mark that is some good information there. That will come in handy for some skills i will use on the galaxy. I also use Barry's on his website which i find really good.

                    Thanks again.

                    Comment

                    • Guest

                      #11
                      Useful info thanks...I have made one very similar, but with a deeper base so I can move the shelf up and down to accomodate deeper components.

                      I use mine in a grill cooker one of those little cheap electric ring things with a grill, its ideal..you need to keep an eye on it, the plastic card rises a little as the air beneath it gets hot then the card starts to sag, I switch on the vac at this time and remove it from the heat and hey presto.

                      Comment

                      • Guest

                        #12
                        Thanks Sub,

                        Nice to see someone else using one of these too, The one I have posted up can be made to basically any size you want, I suppose it depends on the size of plastic sheets available and what you want to Mould with it. I find mine at the size it is now will cater for most things no problems.

                        Regards.......Mark.

                        Comment

                        • Guest

                          #13
                          hi - i,ve just aquired a mattell vac - u - form machine (this one has some instructions) - i presume it works in a similar way - its very old and comes with plastic sheets but i,m after molding a couple of clear canopies with it when i get it up and running - any idea how i find some clear plastic sheet - many thanks, dave

                          Comment

                          • Guest

                            #14
                            Have you tried clear plastic pop bottles, make sure they're empty first. You can get a fair sized sheet out of a two litre one. Its only thin but you should be able to pull a fair depth if you get the temperature right.

                            Costs nothing, and you have nothing to loose. I have used it before now to form gun turret canopies for model boats by heating it up and stretching it over a male mould, with about 50% success rate, but if you are only after one or two it should be ok.

                            John

                            Comment

                            • Guest

                              #15
                              Hi Dave,

                              I usually source my plastic sheet from my local model shop (when I can find one near me that is, they all seem to be disappearing these days !!) apart from that you could try the Pop bottles as mentioned by John in the post underneath yours, this does work well for small parts and some canopies too.

                              Regards.......Mark

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