PrestonE
scholastic sledgehammer
Reged: 04/29/05
Posts: 817
Loc: Houston,Texas
|
|
Hi Bluewater, Thanks for the very kind comments, I am so glad others are able to take something from this journey.
As to the carbon fiber I think the main reason it's not used by every day folks is that for one to get the most benifit, it really does require vacuum bagging. Too much excess resin and the benifits of the carbon go out the window...
Couple that with the cost...glass 5 oz 50 inches wide is around 6-8 dollars per yard and carbon fiber is 55-60 dollars per yard...
But for what we are trying to achieve it's working well so far...and I think the hardest parts are behind us 
Best Regards and keep stoping by,
Preston
--------------------
A few I enjoy,
and a few more in the works ;<)
|
Sky Captain
Scope Builder
Reged: 11/07/04
Posts: 5743
Loc: Seattle Washington
|
|
Hey Preston, can your HS router do aluminum? I like the debris guard around the head unit, did you make it?
--------------------
Equipment Overload!
Kerry.
|
PrestonE
scholastic sledgehammer
Reged: 04/29/05
Posts: 817
Loc: Houston,Texas
|
|
Hi Kerry, I have never tried to cut aluminum on the CNC router yet...just now getting use to cutting anything 
The fingers of polyethylene around the cutting bit are a vacuum shroud that connects to a piece of 4 inch diameter PVC that goes to the shop vacuum system that connects to all of the machines in the wood shop.
I would not be cutting carbon fiber without the vacuum system and even with it wear disposable gloves when working on removing the cut composite parts until they have been totally cleaned of any debris.
Regards,
Preston
--------------------
A few I enjoy,
and a few more in the works ;<)
|
PrestonE
scholastic sledgehammer
Reged: 04/29/05
Posts: 817
Loc: Houston,Texas
|
|
 
The Gremlins to ATM's were in the shop today 
We cut out the first side of the second spider just fine, but after cutting out the 3 triangles on the second side and preparing to move the clamping to the inside, we noticed that the cuts had shifted in the X axis of lenght of the spider by about 1/2 inch...
Likely operator error, and I'm not sure just what I did...but not we will have to do another VARTM infusion tomorrow instead of doing the 10 ply carbon pieces...
Added to that, my metal supplier with whom I placed an order for the aluminum tubing to be used for the CF tubes in the secondary assembly called to let me know that they screwed up and made my last purchase order on the 22nd of July a Quote and not an order...even with my credit card number...go figure...
This will throw everything back by a week for the metal order and a day plus for remaking the second spider...
Hope everyone has a nice weekend...you know what I'll be doing...
Finishing by the end of August will be very tricky. 
Regards,
Preston
--------------------
A few I enjoy,
and a few more in the works ;<)
|
Sky Captain
Scope Builder
Reged: 11/07/04
Posts: 5743
Loc: Seattle Washington
|
|
Thanks...
Quote:
The fingers of polyethylene around the cutting bit are a vacuum shroud that connects to a piece of 4 inch diameter PVC that goes to the shop vacuum system that connects to all of the machines in the wood shop.
Yeah, that makes sense looking back at the set up.
--------------------
Equipment Overload!
Kerry.
|
PrestonE
scholastic sledgehammer
Reged: 04/29/05
Posts: 817
Loc: Houston,Texas
|
|
Quote:
Thanks...
Quote:
The fingers of polyethylene around the cutting bit are a vacuum shroud that connects to a piece of 4 inch diameter PVC that goes to the shop vacuum system that connects to all of the machines in the wood shop.
Yeah, that makes sense looking back at the set up.
Yes, I am trying to balance the new info with the new questions....that so far are few and far between...
Regards,
Preston
--------------------
A few I enjoy,
and a few more in the works ;<)
|
PrestonE
scholastic sledgehammer
Reged: 04/29/05
Posts: 817
Loc: Houston,Texas
|
|
We finished the 3rd spider VARTM this afternoon...hope to CNC it tomorrow...
It appears to be the best of the bunch...
Regards,
Preston 
--------------------
A few I enjoy,
and a few more in the works ;<)
|
BluewaterObserva
Post Laureate
Reged: 05/18/04
Posts: 4763
Loc: Zuni Mtns, NM
|
|
Good to hear.. Practice does make perfect in my experiences.
I'm saving my growing list of questions for assembly time. 
|
PrestonE
scholastic sledgehammer
Reged: 04/29/05
Posts: 817
Loc: Houston,Texas
|
|
Just an update...
Looks like we have a hurricane coming in tomorrow, so we preped for a Cat 1 or 2 in and around the house and shops...
Cut the 2nd botched spider on the OD to recalibrate the CNC and will do the routing of the 3rd composite spider part in the morning...if the storm stays on track to hit the coast afternoon tomorrow...
Also hope to get the 10 ply carbon panels done for the secondary mirror back support...
We'll check in tomorrow if things do not get too bad...which, at this point it looks like 6+ inches of rain and 70+ MPH winds...
Regards,
Preston  ing to the wind gods
--------------------
A few I enjoy,
and a few more in the works ;<)
|
Mike I. Jones
Pooh-Bah
Reged: 07/02/06
Posts: 1102
Loc: Fort Worth TX
|
|
First of all, best of luck with Edouard. They're saying it's supposed to body slam you around lunchtime tomorrow. Maybe it won't tear up too much. We could sure use the rain up here in the Metroplex.
Here are log plots of the results from a spider analysis I did tonight. You can see the effects of offsetting the spider vanes on point source images. These are for a 20" aperture, 150" EFL scope with a 7" central obstruction.
If the offset vanes are parallel to each other, you still only get 4 diffraction spikes, not eight. But there is some interesting sidelobe patterning within each of the spikes due to the vane offsets. I'll look at MTF and ensquared energy effects next.
Mike
--------------------
56 mirrors, lenses, 16" f/6 Newt, 6" f/10 refractor, TOA-130S, Tinsley 5" f/15 Mak, 6" f/4 RFT, Coronado PST. Still to build: 24" f/10 Modified Dall-Kirkham, 10" f/26 Mak, 8" f/12 apo, spectrohelioscope, Herrig, Schupmann, and a new design you'll like.
|
PrestonE
scholastic sledgehammer
Reged: 04/29/05
Posts: 817
Loc: Houston,Texas
|
|
Hi Mike,
Storm is not so bad here yet and looks to be like you said, a body slam with lots of rain.
I just measured the offset to the center of the vane and it's 1.48 inches, so just a bit more than your 1 inch offset would show.
Thanks for helping with the discussion in our group of diffraction effects of the offset spider vanes...I am sure it will make everyone feel a bit better.
Best Regards,
Preston
--------------------
A few I enjoy,
and a few more in the works ;<)
|
rwiederrich
Goldfinger
Reged: 11/17/05
Posts: 6006
Loc: Bremerton Washington
|
|
Quote:
Good to hear.. Practice does make perfect in my experiences.
I'm saving my growing list of questions for assembly time.
Well you can practice *wrong* all day long and you'll never get anything perfect....but if you practice perfectly..then you will have perfect.  
Perfect practice makes perfect.....
Or you can practice badly a lot and you will have lots of bad practice to show off. 
Rob(I don't have anything else to do...)
--------------------
www.goldmtobservingcenter.com
Providing a great place for amateur astronomers, and ATM's to come and enjoy their hobby.
|
BluewaterObserva
Post Laureate
Reged: 05/18/04
Posts: 4763
Loc: Zuni Mtns, NM
|
|
Practicing badly usually leads to perfection.
If it didn't? I'd never get a darn thing accomplished.
OK, perfection is way to strong a term here. In other words the 2nd or even third time around I usually end up with something that finally works.
Edited by BluewaterObserva (08/05/08 06:02 PM)
|
PrestonE
scholastic sledgehammer
Reged: 04/29/05
Posts: 817
Loc: Houston,Texas
|
|
Well I finally got the 3rd spider vane CNCed today...we battling a G28 code at the end of the program that kept driving the bit down to -1" then moving sideways and snapping off the bit...
Well, somehow the Z zero ended up set at -1" instead of at the top of the travel...so instead of going up and out of harms way, it went down and cost time and money
The good news is that the edges are so nice on the 3rd vane...that I may have to do a 4th so that 2 match edge looks wise
I've got to just move forward to the next 10 ply CF plates for the mirror mount...they are "good enough for now"
Pics tomorrow and more VARTM of the flat panels.
Hurricane/storm was a mild one...only about 4 inches of rain so far and winds only 40 ish.
Regards,
Preston
--------------------
A few I enjoy,
and a few more in the works ;<)
|
PrestonE
scholastic sledgehammer
Reged: 04/29/05
Posts: 817
Loc: Houston,Texas
|
|
Mike I think that I can do an offset that you recommend if the 1.48 inches is not good...
It will require me to make differant inter tube sizes, but that is doable...
Please let us know what the optimum offset is and we will look to modify the secondary structure to fit your model...
Best Regards,
Preston
ps by the way the spider vanes are 0.035 inches thick...
--------------------
A few I enjoy,
and a few more in the works ;<)
Edited by PrestonE (08/05/08 08:50 PM)
|
Mert
scholastic sledgehammer
Reged: 08/31/05
Posts: 998
Loc: Spain, Pamplona
|
|
Preston,
Simply awesome this thread, just can't believe my
eyes how well you are machining all of this.
Crazy stuff, have been machining myself a bit but not
to this level of perfection.
Also, your documentation of this great project is
admirable.
All in all, I'd like to thank you for sharing this
incredible project with all of us!
I'll be tuned in to read more and more and wish
you luck, by the way, your advise to do difficult
things in the morning when the head is fresh is
100% sure!
Thanks and regards,
Mert
--------------------
------------------
Mert
42º49"N 1º38"W
3" Unitron refractor
6" F12 SW Maksutov,CS2-S
EQ6 + EQMOD 
Webcam with 1.25" nosepiece
|
PrestonE
scholastic sledgehammer
Reged: 04/29/05
Posts: 817
Loc: Houston,Texas
|
|
Hi Mert and thanks for your kind words...it means a lot.
Well, finally we are getting back on track.
Today we got both flat carbon fiber panels made that will be sandwiched between 2 rings of CF...(yet to be made, metal for the molds is suppose to arrive today )
The squares of CF are 8 inches square and there are 9 layers alternating back and forth 0-90/+-45/0-90 ect...
Infusion took 2 minutes and then sat at 185 deg F for 75 minutes with the vacuum on.
Dry weight of the CF 76.4 grams and final infused weight 115 grams...both individual infused pieces are within 0.2 grams of each other in weight, but about 75% of all this will be eliminated in machining the carbon fiber rings for the secondary.
If you go back to the cut away of the secondary, these panels are the 2 that attach to the mirror in the sandwich.
The first pic is of the whole composite in the nylon, flow material, ect just out of the cure oven before being stripped of everything.
--------------------
A few I enjoy,
and a few more in the works ;<)
|
PrestonE
scholastic sledgehammer
Reged: 04/29/05
Posts: 817
Loc: Houston,Texas
|
|
After removing all of the layers we are down to the first of the 2 panels.
--------------------
A few I enjoy,
and a few more in the works ;<)
|
PrestonE
scholastic sledgehammer
Reged: 04/29/05
Posts: 817
Loc: Houston,Texas
|
|
A close up showing just how flat this system of VARTM suck the carbon fibers down and together.
You can see the change in fiber orientation of the alternating layers, but no differance in height.
--------------------
A few I enjoy,
and a few more in the works ;<)
|
PrestonE
scholastic sledgehammer
Reged: 04/29/05
Posts: 817
Loc: Houston,Texas
|
|
The 2 finished CF panels ready to go the the CNC router after we make the CF tubes and program in the finished sizes.
And the 2 good spiders that have been CNCed on the router.
We are finally getting somewhere.
--------------------
A few I enjoy,
and a few more in the works ;<)
|
Previous
Index
Next
Threaded
[Re: 
Edit
Reply
Quote
