How to get a gloss finish one B side with resin infusion


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zappafile123
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Hi there,

I'm new to making CF products and am after some tips on how to achieve a high gloss finish on the peel ply or B side of a small part made with resin infusion. Specifically I'm making custom road cycling shoes using a plaster casts of my feet. I successfully made my first sole on the weekend (laying up the carbon over the foot cast followed by peel ply and a full vacuum bag enveloping the entire foot cast), but have encountered the minor problem of requiring a smooth finish on the inside and outside of a part. I need a smooth finish on the inside so my foot is comfortable, and a neat finish on the outside so it looks good. As you can see from the first two images below, the peel ply leaves a pretty rough finish and I'm guessing from what I've read that thats just what peel ply does no matter what. What can do to make it look good like the third image below? I guess I could make a second carbon mould over the top and use that to sandwich the carbon, but that's too much effort, especially if I want to make shoes for local cyclists to get a bit of cash on the side of my day job. Would painting on some extra resin after moulding and then sanding and buffing it work? 
Further, I imagine I ended up with those big wrinkles on the outside finish because I wast careful about how I applied the peel ply. Tips on getting that smooth are also welcomed (just use adhesive? (cause I didnt!))

Thanks in advance!


 notice the gloss finish inside and outside the shoe
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Chris Rogers
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That's a tough one!  You'll need a mold or some kind of tooling to shape any surface you want to directly control.  Given the shape this means a multi-part mold on the outside if you want a complete shoe shape like your bottom picture.  This will be hard to make just with plaster - but you could build a part, fair it out with filler and make it shiny (and a uniform thickness) and then make an external mold - probably in multiple pieces with flanges - to shape the outside.  If you are just trying to make the bottom of the shoe like the kevlar lined parts then it could be done with just single part inside and outside molds.  The tolerances would have to be right to give the right thickness (infusion is more forgiving because resin will just add extra thickness) but having one mold be flexible would be best.  Silicone would be a good material to make a flexible mold that would give a decent surface finish  This would probably be the easiest way for producing many parts - metal or composite molds to shape the outside geometry with a silicone foot shaped intensifier/mold/liner to expand inside and give the inside compaction and a pretty surface.  This could be inflatable (better) or solid (ok) and would ideally expand with heat or internal air pressure.  Bike manufacturers have this process pretty well developed for frame parts.  




zappafile123
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Chris Rogers - 4/8/2020 3:43:27 PM
That's a tough one!  You'll need a mold or some kind of tooling to shape any surface you want to directly control.  Given the shape this means a multi-part mold on the outside if you want a complete shoe shape like your bottom picture.  This will be hard to make just with plaster - but you could build a part, fair it out with filler and make it shiny (and a uniform thickness) and then make an external mold - probably in multiple pieces with flanges - to shape the outside.  If you are just trying to make the bottom of the shoe like the kevlar lined parts then it could be done with just single part inside and outside molds.  The tolerances would have to be right to give the right thickness (infusion is more forgiving because resin will just add extra thickness) but having one mold be flexible would be best.  Silicone would be a good material to make a flexible mold that would give a decent surface finish  This would probably be the easiest way for producing many parts - metal or composite molds to shape the outside geometry with a silicone foot shaped intensifier/mold/liner to expand inside and give the inside compaction and a pretty surface.  This could be inflatable (better) or solid (ok) and would ideally expand with heat or internal air pressure.  Bike manufacturers have this process pretty well developed for frame parts.  

Hey Chris, thanks for your thoughts. I'd always make the shoe in two parts and just use carbon adhesive to join the sole to an upper. I need to use an epoxy flexibiliser to make the upper portion malleable so I can bend it to get my foot in and out of the shoe as well as tighten it up with some laces when I'm wearing it.

The silicone idea is interesting. But it's a little challenging to visualise how it would work/be practical particularly if it was inflatable. It could be reasonable to make a solid silicone outer mould if I had a set of standard shoe sizes. However, the whole point of this product is that it's bespoke to the individual foot so I would need to make a new mould for every foot. It's already quite time consuming making one shoe as it is. 

All I need is for the B surface to be wrinkle free, and be aesthetically pleasing. I plan to make shoes for myself primarily but then see if I can sell some shoes to local club riders so I can repay the outlay of the initial investment in materials and equipment which was around $2000 (AUD).  

Hojo
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zappafile123 - 4/10/2020 1:09:44 AM
Chris Rogers - 4/8/2020 3:43:27 PM
That's a tough one!  You'll need a mold or some kind of tooling to shape any surface you want to directly control.  Given the shape this means a multi-part mold on the outside if you want a complete shoe shape like your bottom picture.  This will be hard to make just with plaster - but you could build a part, fair it out with filler and make it shiny (and a uniform thickness) and then make an external mold - probably in multiple pieces with flanges - to shape the outside.  If you are just trying to make the bottom of the shoe like the kevlar lined parts then it could be done with just single part inside and outside molds.  The tolerances would have to be right to give the right thickness (infusion is more forgiving because resin will just add extra thickness) but having one mold be flexible would be best.  Silicone would be a good material to make a flexible mold that would give a decent surface finish  This would probably be the easiest way for producing many parts - metal or composite molds to shape the outside geometry with a silicone foot shaped intensifier/mold/liner to expand inside and give the inside compaction and a pretty surface.  This could be inflatable (better) or solid (ok) and would ideally expand with heat or internal air pressure.  Bike manufacturers have this process pretty well developed for frame parts.  

Hey Chris, thanks for your thoughts. I'd always make the shoe in two parts and just use carbon adhesive to join the sole to an upper. I need to use an epoxy flexibiliser to make the upper portion malleable so I can bend it to get my foot in and out of the shoe as well as tighten it up with some laces when I'm wearing it.

The silicone idea is interesting. But it's a little challenging to visualise how it would work/be practical particularly if it was inflatable. It could be reasonable to make a solid silicone outer mould if I had a set of standard shoe sizes. However, the whole point of this product is that it's bespoke to the individual foot so I would need to make a new mould for every foot. It's already quite time consuming making one shoe as it is. 

All I need is for the B surface to be wrinkle free, and be aesthetically pleasing. I plan to make shoes for myself primarily but then see if I can sell some shoes to local club riders so I can repay the outlay of the initial investment in materials and equipment which was around $2000 (AUD).  


You can get fairly smooth surfaces using bladder. You wouldnt likely infuse, but use prepreg or wetlayup.

GO

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