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Improved glue squeege , mandrel, roving system

Hey guys, we tested out a few new mods to our machine, and had some great success with our last wind.We removed the plate/roller/lucky band squeege system as it was proving inconsistant.We made a new bracket for the squeege roller, out of two 90 aluminium angle metal. ( one each side )We drilled a hole for a stationary roller , and a slot next to it for A sliding or adjustable roller, so we have two rollers that squash together, and you can adjust the gap between them for the thickness of your carbon roving, , or leave them loose and use rubber band to adjust the tension between them. Works great !.Another MOD we did stops the roving moving to the edge of the metal feeder and jamming in the gap, which happens if you wind non circular mandrels ( we did square ) . We just put a small circular guide ring just before and right next to the middle of the metal feed roller, and it's enough to always keep the carbon on the final roller :)Final MOD we did was test a collapsed mandrel, which we made in two halves, as we have straight sided mandrel, we can have a gap along that edge 2-5 mm no issues, and we squash the two wood halves onto a metal plate or rod in the middle, and wrap ends with tape to Hold. Rods are removed after resin cured, mandrel collapses in by a few mm, and tube can be removed :)

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  • Hi Justin, 

    I can't because I done have access to it, but it was pretty simple - here is the description

    Say you want a square shaped mandrel.

    You have a big square mandrel, cut it 1/3 the way up along the entire length, and take out 3 - 4mm, so you have a big piece ( 2/3 ) the thickness minus a mm or two, and a smaller piece, 1/3 the thickness minus a mm or two.

    Next  - we found some aluminium plate - 3mm thick and 50mm high, and we are using this to hold the two mandrel sides together.

    Then we cnc'd a 3mmthick x 50mm high groove into the left and right sides of the mandrel for the 3mm aluminium to sit in, so that when you push the aluminium onto the left and right side of the two pieces of wood, the wood sits at the correct height, and there is a 3-4mm gap in the middle.

    The gap is used, as once you have finished the build, you pull out the aluminium plates - I normally pull one from one end, the other from the other, and then the two wood pieces can collapse by 3-4mm gap you had between them, and they fall out after that

  • Hey, could you post a couple of pictures of your collapsible mandrel setup?  I have been struggling with finding a method to easily remove mandrels once the carbon fiber has been wound around it.  

  • We now removed the yellow arm, and instead installed another metal roller above the last roller on the delivery head, all this does is increase the time it takes for the carbon on the last roller, to move off center, by which time the head has rotated and there is not the issue of carbon hitting the edges of the roller.

  • Hi Nicholas,

    That is a great looking system. I would love to see some of the shapes you have been winding with this one!

    Also, how is the vac bagging going? Can you get a consistent OD like this? I have considered winding around an inflatable mandrel and then chucking it into a mould, but it all started to get a bit hard and costly! 

    Cheers,

    J. 

  • Hey guys - after these mods, this is how the machine improved

    Resin control - it's very easy to adjust the amount of " squeegeing " happening to the carbon by adjusting the elastic bands, in the pic, I have it doubled up, which is high squeegee, which saves glue, and lets me wind generally with only 1 tub of glue and around 5 layers. after this I vacumm bag and still have excess resin squeeze out in that process.

    You note the yellow plastic piece I out on the end of the delivery arm. This is becaus I am winding all kinds of crazy shapes. If I just have the roller, when the carracge gets to the end and reverses and any reasonably high angles, like 60 degrees, definataly 45 degrees, then the carbon slides to the corner and pinches between the roller and the sides of the delivery arm, which bunches the carbon up, and then cuts the TOW. The yellow piece is a guide, that is placed close to the roller, to ensure the carbon allways is in contact with the roller, and never hits the edge of the roller.

    I have an alternate design for this which I think may work better, that is to remove the yellow guide, and install a second roller just before, and abover the first roller. The extra friction of two rollers trying to center the tow should probably overcome the momentary force at the ends of each layer, as th mandrel changes direction and tries to yank the tow to the edge again. Don't know where you would need the roller exactly, but I would try as close as possible, and maybe 45 degrees up as you look back towards the spool. - If that didn't work move it to 90 degrees up.

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