PrestonE
scholastic sledgehammer
Reged: 04/29/05
Posts: 817
Loc: Houston,Texas
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Cured CF on mandral just out of oven.
Look, NO Wrinkels 
It appears to have worked.
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A few I enjoy,
and a few more in the works ;<)
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PrestonE
scholastic sledgehammer
Reged: 04/29/05
Posts: 817
Loc: Houston,Texas
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It did work, so it's time to cut to length and square the ends...
The wet layup as we did it only took about 45 minutes start to finish, including cutting the CF and through placing into the oven...this is much quicker than doing the VARTM and almost as good a fiber to resin ratio.
It is messy though if your not careful.
--------------------
A few I enjoy,
and a few more in the works ;<)
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PrestonE
scholastic sledgehammer
Reged: 04/29/05
Posts: 817
Loc: Houston,Texas
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Here are all 3 tubes. The 4 inch ID by 8.5" long is to the left and weighs a mear 94 grams with a wall thickness of only 0.040" but is quite stiff.
When bonded into the end plates it will be very very stiff.
The small tube still needs to to cut to lenght and then we can take measurements to program the Gcode for the CNC router to cut out the flat CF plates we made last week.
Too bad we need 2 more, but we will work on those shortly.
So there is the work since last Thursday the 7th of August.
Will we finish by months end 
Only the big guy knows...
Hope you enjoyed this update.
Regards,
Preston
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A few I enjoy,
and a few more in the works ;<)
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Gene Hunter
super member
Reged: 12/29/07
Posts: 194
Loc: SC
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Preston thanks for sharing your methods here. I understand better what you where saying on the phone now. So the last tube you did you did not Vacuum Bag correct? I am guessing because CTE does not matter much.
I think my next effort I am going to do a female mould again and do it like we discussed where I let the first layer set before putting on the other layers and vacuum bagging.
keep posting , I like the photos a lot.
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Clear Skies
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PrestonE
scholastic sledgehammer
Reged: 04/29/05
Posts: 817
Loc: Houston,Texas
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Hi Gene, Yes the last 2 tubes were done wet layup but are around 65/35 fiber to resin content...almost as good as we have gotten from the VARTM method...
And Yes, these pieces are critical as to length and the coefficient of Thermal Expansion...and will work well in the secondary assembly.
By using the second layer of poly over the epoxy and carbon fiber, we are able to remove with the squeege just about the right amount of excess resin to hit our desired target ratio for fiber to resin...
It's quicker in this instance, and dirtier, but worked.
We hope that this will encourage others to try this trick to do light weight composites that are almost as good as a vacuumed bagged item.
Best Regards, and nice to talk to you yesterday.
Preston
--------------------
A few I enjoy,
and a few more in the works ;<)
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Gene Hunter
super member
Reged: 12/29/07
Posts: 194
Loc: SC
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well that certainly is a good trick to know. I would not mind trying it on a larger tube frank and I are making for him to make sure he gets the right ratio. I think its going to be something like 15" in diameter and about 66" long. I have been dreading it because its so large and I had concerns about a wet layup that large. this technique will go a long way toward making that easier. We are planning on running the fiber longwise one layer at a time. This technique I think would give us the best shot at sucess.
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Clear Skies
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PrestonE
scholastic sledgehammer
Reged: 04/29/05
Posts: 817
Loc: Houston,Texas
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Gene I wish you good luck my friend...
That's an very large tube 15 inch OD by 66 inches long...
Please post pictures...
Regards,
Preston
--------------------
A few I enjoy,
and a few more in the works ;<)
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Gene Hunter
super member
Reged: 12/29/07
Posts: 194
Loc: SC
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preston do you always make mandrels out of solid metal like this? My approach was to use a slip roller and I am thinking that you are just using what your more familiar with. But I can see advantages of a hard metal mandrel.
The mandrel you have could be used over and over again without problems whereas my slip rolled tube gets bent out of shape after a few uses. Which would you prefer? Mine would cost less and be faster to make but yours will last and last.
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Clear Skies
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PrestonE
scholastic sledgehammer
Reged: 04/29/05
Posts: 817
Loc: Houston,Texas
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Gene, For a large tube the slip rolled tube with the edges butted would work just fine. I've done that in the past.
For the small tubes I find it works better to turn the tubing to get it very round and uniform. In addition, making a slip rolled small tube is more difficult as is getting the tube out afterward.
One of the keys to this working so well is the heating of the composite while it's curing on the tube. I helps tighten the carbon fiber by expanding with the thermal expansion of the aluminum.
It's also nice to have the tube fully cured in just 1 hour so you can proceed with any machining.
Glad you have shared this method with you.
Regards,
Preston
--------------------
A few I enjoy,
and a few more in the works ;<)
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PrestonE
scholastic sledgehammer
Reged: 04/29/05
Posts: 817
Loc: Houston,Texas
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We did a 16 layer CF this afternoon....
But I have to say...there are a few following our build that are looking to take it commercial...
To those, I did this on a public forum to document the progression...as we apply for US patent protection...
Best Regards...and Im not sure just how much more will be disclosed in this forum...
This may be the end...I'll leave that to the powers that be..
Very Best Regards My Friends,
Preston
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A few I enjoy,
and a few more in the works ;<)
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CoreDump
member
Reged: 11/06/06
Posts: 36
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Quote:
This may be the end...I'll leave that to the powers that be..
Hi Preston,
This is very sad if it ends like that. Your post is a gold mine for learning.
The part about CF infusion is really a great knowledge addition to the ATM community, and looking at your machining skills push me to improve mines!
Keep up the good work!
Regards
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BluewaterObserva
Post Laureate
Reged: 05/18/04
Posts: 4763
Loc: Zuni Mtns, NM
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I can see your point about it.
Maybe less detail would be in order? 
I was so looking forward to the assembly stage. All this type of engineering and manufacture is a beyond me.
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Gene Hunter
super member
Reged: 12/29/07
Posts: 194
Loc: SC
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Preston I have certainly enjoyed our coversations on the phone and here. I wish you the best and I certainly understand and respect your right to your intellectual property. Perhaps you could keep us posted though on your progress.
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Clear Skies
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PrestonE
scholastic sledgehammer
Reged: 04/29/05
Posts: 817
Loc: Houston,Texas
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Ok, everything has been looked at and we're given the green light to continue posting in the detail that we have in the past...
Thanks for understanding...
We have been going over the Secondary Assembly with regards to how it attaches to the Upper Ring.
Unfortunately, my laptop was slowing to a crawl with the size of the build file for the lower portion of the OTA...so I copyed just the top ring and worked out the Secondary Assembly without the Upper Truss Tubes and Catch Blocks...
  BIG MISTAKE as there is an interferance between the Spider Vane End Blocks and both the Catch Blocks and the Tube Ends...
Thankfully I caught it before machining any of the CF pieces...  when I combined the 2 seperate 3D models on a faster computer
but just how many of the CF pieces will still be useable in a redesign will be the next question...
This will likely take up the whole weekend, so don't expect to see any updates...unless I get real lucky...until next week.
Best Regards,
Preston
--------------------
A few I enjoy,
and a few more in the works ;<)
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PrestonE
scholastic sledgehammer
Reged: 04/29/05
Posts: 817
Loc: Houston,Texas
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Well we got lucky
But in the process found that the secondary assembly as designed before this little problem of interferances reared it's ugly head would not fit into the secondary ring without bending the carbon fiber vanes
We normally build models in wood before finalizing things to design to check for these sort of problems, but with the time line approaching rapidly...didn't do the models...IT'S really cost us in lost time and energy
Got a fix for both problems that are modeled and in CAD now.
Just finished producing the Gcode for machining the carbon fiber plates for the secondary assembly, and everything is usable and as designed before....just had to move it about 2 inches above the Upper Ring.
Now to edit the Gcode so we can CNC router the carbon panels tomorrow morning.
Will start posting pics of the process tomorrow. 
Regards,
Preston
--------------------
A few I enjoy,
and a few more in the works ;<)
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Scott Milligan
super member
Reged: 09/08/05
Posts: 112
Loc: MA
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Preston:
A very interesting (and impressive) project. Also, I think you may have established a new CN record for thread length, so tell us, when can we expect to read the book?
Party on, dudes!
Scott
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PrestonE
scholastic sledgehammer
Reged: 04/29/05
Posts: 817
Loc: Houston,Texas
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Hi Scott, Coming from you that's quite a nice complement...Thank You Sir
I really never had any idea the thread would get this many views, and will likely hit 10,000 before we are finished and have first light.
Here's what we came up with over the weekend after jury rigging up the secondary with wood, on old computor to set things up on ect...
This raised the spider vanes up about 2 inches above the original location and now they do not interfer with anything.
--------------------
A few I enjoy,
and a few more in the works ;<)
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PrestonE
scholastic sledgehammer
Reged: 04/29/05
Posts: 817
Loc: Houston,Texas
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Next up is the Carbon fiber Mirror mounting plate. There will be a second plate of similar size but with the 3 collimation ball swivel holes.
The 2 CF plates will be located about 1/2 inch apart and joined with an outer CF ring, and CF tubes at the colimation points and in between to increase the ridgity.
Here's the plate just before drilling the collimation holes.
--------------------
A few I enjoy,
and a few more in the works ;<)
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PrestonE
scholastic sledgehammer
Reged: 04/29/05
Posts: 817
Loc: Houston,Texas
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This is one of the Spider Vane Support Plates. There are 2 spaced just over 6 inches apart that mount to a central CF tube and the 2 outer small tubes that go through the small outer holes in the disk.
The CF spider vanes than go around the CF tubes and attach at the outer ring. They will be adjustable in squaring to the opposite vane and tiltable to square to the light path.
--------------------
A few I enjoy,
and a few more in the works ;<)
|
PrestonE
scholastic sledgehammer
Reged: 04/29/05
Posts: 817
Loc: Houston,Texas
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And finally the dry assembled parts.
On the right is the Mirror Mount assembly. It lacks the outer CF ring and interior CF support tubing, but shows just how well the fit is coming from the CNC router.
At the top of the CF tube will be a Nylon bushing that has the outer edge rounded like an Oring. This will fit into the larger tube of the Spider Support assembly and keep the secondary centered.
On the right is the Spider Support assembly again dry assembled and without the outer small tubes.
That's all for today and I'm glad that none of the CF parts were lost due to accidents in machining or operator error.
Regards,
Preston
--------------------
A few I enjoy,
and a few more in the works ;<)
|
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