Carbon tube for 10" OO mirror

[Gina]

I've never found the need to degas a Christmas pud! 🤣

[Robert72]

On 04/11/2019 at 09:47, Gina said:

I've never found the need to degas a Christmas pud! 🤣

You only need to do that if you're after a Christmas pancake.

[Robert72]

When I said I had finished the mould I was lieing. Well fibbing, but not intentionally.

Today I have been adding female M4 threads in the form of brass spacers to the ends of the mould.

16 equidistant at each end.  For the webbing posts to screw in to.  I was going to cut slots, but this is more satisfactory.

Not pretty but it will do the job.  Unfortunately I dripped some resin into the mould, so the ends will need another buff and polish. Bah, it seems neverending!

Lay up coming soon I promise!

 

[Rusted]

2 hours ago, Robert72 said:

When I said I had finished the mould I was lying. Well fibbing, but not intentionally.

Today I have been adding female M4 threads in the form of brass spacers to the ends of the mould.

16 equidistant at each end.  For the webbing posts to screw in to.  I was going to cut slots, but this is more satisfactory.

Not pretty but it will do the job.  Unfortunately I dripped some resin into the mould, so the ends will need another buff and polish. Bah, it seems never ending!

Lay up coming soon I promise!

 

I should have a lie down first.  You'll be exhausted after clearing all that snow off the tube!

[Robert72]

Hello all. Just another update. So a few posts ago I may have mentioned that one of the mould halfs was slightly distorted, slightly off circular. It has been annoying me a bit, so I have made the decision to apply external stiffeners to both sides. The pattern has been placed back into the mould and bolted tight. The intention is to bond 9 ply/styrofoam/ply formers, externally to each half. These will then be glassed over, and with any luck the mould will retain its shape. Apologies to anyone following this progress, and keen to see this complete (I know I am too), but I really want to get this right, not only for the first mould but any, or all, others. Will keep the posts going, and continue with the modification asap.

[Robert72]

The Vacuum chamber lives!!!!  Just did a trial run with a glass of water, and it degasses like crazy.  Holds a vacuum too. Pic to follow:

[Davey-T]

Building up the suspense nicely Robert 

Dave 

[Robert72]

I'm not sure about suspense Dave, just wait till you see the mould stiffeners I have planned.  Still I have all the materials I need for that and the project goes on.

 

I thought I would post the pic of the vac chamber, as it at least shows something is complete!

[Robert72]

Rear Cell Refurb:

A bottle of "No-Nonsense" paint stripper, and a can of "No-Nonsense" matt black primer should do the trick:

[Robert72]

Have commenced adding the external formers to the mould. These are ply/styrofoam/ply, and will be glassed over.

[Rusted]

Nobody could accuse you of not being thorough!

You should get a job at CERN. They like doing things on a grand scale!

[Robert72]

3 hours ago, Rusted said:

Nobody could accuse you of not being thorough!

You should get a job at CERN. They like doing things on a grand scale!

Speaking of doing things on a grand scale......

 

 

[Gina]

Yep!  That's BIG!!

[Robert72]

External formers completed. The roundness is very good now, I think it may have been out more than I thought, so I am glad I did that.....

Cutting the cloth has commenced.  Just to be a bit different the outer laminate is going to be a combination of carbon plain weave and carbon/kevlar plain weave (this may go part way to overcoming brittleness Rusty?).  This is very difficult to achieve with any semblance of professionalism or neatness, so I am either being very brave or very stupid.  Quite probably the latter.  At least it will be interesting if nothing else.....

[Rusted]

Well done. I have no direct experience of CF. Only glass fibre and cloth with polyester resin.
It would be humanly impossible to make your tube any uglier than mine. I was working on the outside!

 

 

[Robert72]

OK, so the first layup attempt didn't work out very well at all.  I managed to get the cloth into the mould but it was a bit of a shambles.  On hold for a bit until I do a bit of head scratching.  Current thinking is to use a single, heavyweight (650g) sheet for both the inner and the outer in order to simplify and rationalise the layup.  And possibly give the mould a spray of epoxy compatible polyester gelcoat in conjunction with a spray of acetone on the inside surface of the cloth to tack it to the mould. Yes, plenty of options.  Spraying the mould will require some warmer weather, in the mean time I am going to step back for a bit and have a think about the best way ahead.

[Robert72]

So, continuing with the first attempt after all.  Vacuum bagged to attempt to de-bulk the outer skin, so I can cram in the core material, then the inner skin. Images:

[Robert72]

The core material is in. This is 3mm 3D CORE PET 100 Foam......

[Robert72]

First layer of inner skin is going to be laid in four overlapping segments.  Here is the first one.....

All of the segments are now in, and looking good.  The final, and innermost skin I will put down in one piece, so only one edge is visible.  This will give 2/3 inner skins.  Should be enough I think.

All being well, I think we should be looking at next weekend for an infusion.

[Robert72]

The innermost skin is now in.....

If I manage to get back on Friday, then it is full ahead with the infusion bagging materials Saturday morning/afternoon, and infusion Saturday afternoon/evening.

I think I may have bridging issues though especially with the innermost materials.  If so it makes life more difficult when it comes to installing the rear cell.

Edited January 19, 2020 by Robert72

[Robert72]

Well another update.  The bagging consumables have been applied.....

So in there now is polyester peel ply, infusion mesh (400mm at each end), and vacuum connectors with infusion spiral at the uptake end.

A new bag has been applied, as the last one was made of two pieces with 6 joins.  I left the old outer bag on though for added puncture protection. The new bag is single piece with one join at one end......

The drop test seems to be holding up, however I think there is a slight leak at the catch pot.  The infusion spiral also need a slight reposition to get it back on to the mesh.  Just tweaks here and there, and the resin goes in asap.

Have a nice weekend folks!

[Robert72]

Wow, it's been a while since I posted. Still no progress as of yet, with work and other stuff.  The outer reinforcements will be getting filleted, as these are giving rise to mould/bag interface voids, where the bag doesn't want to conform.  And another attempt at bagging.  Maybe next weekend.

[Robert72]

Filleting added to mould reinforcements, to overcome bagging voids.....

This is just anti-crack filler.  Next I will give the whole of the mould a coat of primer.  There are a few sharp spots that may be piercing the bag when under hard vacuum (I am having issues achieving a full seal on the bag), the primer will cover the minor ones, the remainder being easy to spot and rub down.

[Robert72]

Time to proceed with the project now that I am back in the UK. Almost a year since the last post! Finally got the mould and layup properly enveloped and have completed the infusion. Here is a video of the final stages of infusion with the resin and residual air escaping:

[Davey-T]

Good to see you're still persevering, thought you'd given up.

Dave