PrestonE
scholastic sledgehammer
Reged: 04/29/05
Posts: 817
Loc: Houston,Texas
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Thanks to All that have got us to over 5000 hits...in this short time...
Very Best Regards,
Preston
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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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Here is a rendering of the Secondary Assembly without the fixtures to hold and adjust the outer ends of the carbon fiber spider at the Upper Ring.
The mirror is attached with silicon to the carbon fiber disk in 3 spots in a 90 degree pattern, not the typical 120 degree location...Mike convinced me of the merits of this as collimation is now tilt/tip and very intutive.
We have the Ball Ends captured with a second carbon fiber disk, and then stiff springs between that and the next CF plate above.
The lower CF tube extends into the inside of the upper CF tube and is again supported around the inside by an O-ring to prevent lateral movement, but allow collimation or Secondary Spacing without binding.
The spiders are in the form of a 90 degree bend so that the vanes are parrellel to each other but are off set from the center to increase stiffness. They wrap around 2 CF tubes 3/4" diameter that go from the lower CF plate and into the upper CF plate.
We will start fabricating all of the carbon fiber pieces tomorrow.
Glad to have this one behind me. 
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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Here is a closeup without the Upper Ring and Spyders to be able to see the details a bit better.
--------------------
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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Ok, Back to work...You've had enough time away from this 
Since the aluminum tubing did not arrive via UPS we will start with the Spider's...
But first we needed to make a radius form to use in the sheet metal brake...
So our CF tubes that the spiders will wrap around are 3/4" in diameter, thus we want the ID of the radius 3/4" right 
Wrong, but I made the 3/4" raduis adapter first before I woke up 
We have to take into account the thickness of the aluminum sheet used for the mold and the Flow material for the VARTM that goes on top of the mold...so we made a second smaller radius form...
3/4" on the left and correct one on the right.
--------------------
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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Close up of the correct bending form on the aluminum sheet in the sheet metal break.
You can see that the left edge of the bending form is right over the axis that will fold up and round the sheet aluminum to our radius.
--------------------
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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As we lift the bending handles on the brake, the sheet bends up and around the radius form that we made, making a nice radius on the mold.
--------------------
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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Closeup of the bend in the brake at 90 degrees.
--------------------
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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Now we layed out the shape of the Spider on the mold and have taped down the nylon bagging material.
--------------------
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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After the bagging material, in the following order were Flow material, Peel Ply, 5 oz carbon fiber, 5 oz strips of unidirectional carbon fiber, aramid fiber and then reverse.
The aramid is the middle layer and is there for safety. Should the carbon fiber ever break, the aramid will hold things safely together protecting the secondary and primary mirrors from damage.
Carpenters square is there to make sure that the uni CF is in the correct place before covering it with the next layer of carbon.
Once infused and cured, we do not want to worry about where that Uni CF is when we us the CNC router to carve up the laminate.
--------------------
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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So the last layer of 5 oz carbon is on, Peel Ply, Flow material, the resin and vacuum manifolds are in, the top nylon bagging material is sealed.
Now we have clamped the squaring blocks on the top and bottom of the mold to that it does not change shape when we pull the vacuum...without them, it would tweek and the finished part would be junk. 
I've made this mistake before and learned the hard way 
--------------------
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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Finally, into the curing enclosure for the vacuum test...
Looks great!!!
No leaks, so we will infuse this one first thing in the morning and then set up to do the second of the 2 in the afternoon.
Now I have to hit the books to retrain my old brain just how to program the CNC router to machine out the pattern you saw in the rendering above.
Until tomorrow.
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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Ok, a quick retest for any vacuum leaks...good to go...turn on heater...let temp climb to 140 deg F ...mix resin and start the infusion
 why is it taking so long to suck up 370 grams of resin, I mean it's been almost 5 minutes and it's only taken 1/2 of the mix
Finally after 10 minutes resin is just starting to get into the vacuum tube...something is not right
Well, we cannot stop now...so we will let it finish, cure for 75 minutes at 165+ deg F and let her cool down to see just what happened.
Pic after removing from the curing chamber...you can see excess resin in the lower right corner that is almost 1/2" thick...
This is diffently not looking good  will this be a total waste?
--------------------
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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In this shot you can see where the resin has not gone across the top of the mold...may have been a small air leak
that developed once the heat was applied...
With 26 inchs of vacuum, I cannot see just how there could be a build up of that much resin in the bottom right corner by the resin inlet...
Looks like we will need to take the entire thing off of the mold.
--------------------
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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Close up of resin build up next to resin intake manifold.
--------------------
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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That was not a very pretty picture...let's see what the back side of the composite looks like...
Not bad...looks like we had better try to remove everything from the inside first.
--------------------
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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So the screen Flow Material and the Peel Ply came off fairly easily...and the surface of the carbon fiber looks good.
Will this be able to be saved
--------------------
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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Ok, now that I have retyped this for a 3rd time...
I keep hitting some key on the laptop that deletes the
entire message.
We started pealing the Flow material from the thin area
near the vacuum manifold ...where the resin did not
infuse all the way at the top.
It's harder than normal as the resin is thicker and as
we get to the radius at the middle it get tough to peal.
Pealing toward the thick resin section is very hard
and I worry that the carbon laminate may get damaged
when all of a sudden POP the whole thick section
comes of at once...
But as you can see, it's all just fine.
--------------------
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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Let's see if the radius of the mold was calculated correctly by placing a 3/4 aluminum rod in place.
Looks nice. 
--------------------
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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But does it really fit well
The close up tells the story.
Now we need to just make another on just like this, but without the excess resin if possible.
--------------------
A few I enjoy,
and a few more in the works ;<)
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Sky Captain
Scope Builder
Reged: 11/07/04
Posts: 5743
Loc: Seattle Washington
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That's just getting "crazy cool" Preston! 
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Equipment Overload!
Kerry.
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