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fiberglass vacuum layup
By Rover, Section Wind Posted on Sun Mar 08, 2009 at 08:59:58 PM MST
my new rig for vacuuming layups

I got tired of PVC blades and their tendency to warp, also I have a hard time finding pvc with anything greater than a 6" diameter. So I decide to go fiberglass, using concrete tubes as templates , which I can get up to 12"
Normally I would do hand layup without vacuum , but I want to get as thin/strong as possible . So I build a vacumm rig that uses my shop vac.
The test layup was (from bottom to top , 9 oz standard cloth , 2 layer of 24 oz bi-axial cloth, then the finishe layer of 9 oz. The point of all this is to end up with blanks that I can cut to suite what I want to do... basically 36" blad with a 5" to 2" taper.
Here are some photos of the first test, the shop vac pulled enough vacumm to get the final layup at less that .1 inch (.09 actually). I use a light dimmer with enough amp capacity to turn down the shop vac.

fiberglass vacuum layup | 7 comments (7 topical)

Re: fiberglass vacuum layup (3.00 / 0) (#1)
by Rover on Sun Mar 08, 2009 at 03:10:42 PM MST

The strange looking 4 th picture is me preparing sections of 10" concrete tube. I do a prelim fill with spray foam, then I'll cur off the excess, and fill the voids with plaster of paris. Reason is that during my test, the vacuum deformed my template ( even though it itself had 3 hand layups.. )

{There are no typos in my post, I have my own language... (dictionary available upon request for an added cost})

Re: fiberglass vacuum layup (3.00 / 0) (#2)
by dnix71 on Sun Mar 08, 2009 at 03:48:39 PM MST

We have 2 vacuum frames in the shop about that size. We laminate lithos with brush on glue. Presses also have small vacuum pumps on them to pick up stock that won't friction feed. Those have a needle valve bleeder to adjust the vacuum.

Re: fiberglass vacuum layup (3.00 / 0) (#3)
by Rover on Tue Mar 10, 2009 at 04:23:40 AM MST

Well the test piece came out great, no I just have to worry about deforming the molds when I do the real thing.

I did what I said and filled the voids of the mold with hydraulic cement. (Bad Idea)

In the future if anyone reads this and uses cardboard concrete tubes , don't do what I just did, the hydraulic cement deformed the tubes (I'm an idiot I should have thought of the water content and what it would do to the carboard). I'm going back to just filling completely with spray foam, hopefully that will be enough rigidity.

{There are no typos in my post, I have my own language... (dictionary available upon request for an added cost})
[ Parent ]

Re: fiberglass vacuum layup (3.00 / 0) (#4)
by Kilroy2k1 on Thu Mar 12, 2009 at 04:58:34 PM MST

Shop vacs usually dont like to be under full load for long periods of time. If you can find any old refrigerated device, fridge, cooler, freezer, and relieve it of its compressor. Of course make sure the system is properly purged before hand. ;) A refrigeration pump will pull a really good vac on your setup and as the other gent said you can put a bleeder valve on the line to control pressure in the frame.

Tom S.

Re: fiberglass vacuum layup (3.00 / 0) (#5)
by Rover on Fri Mar 13, 2009 at 04:56:07 AM MST

If I had a vacuum pump I'd use it, but I don't, so I did a test with the shop vac, and I am happy with the results.

I don't run the vac at full speed, I'm running it off a rheostat. In my test run I slowly brought it up to about 3/4 of its capacity for about 15 minutes then backed off to less than 1/2 for 2.5 hrs. I was worried about the rheostat being able to take the amperage, but it did fine.

The 4 layer layup 10" X 25" cloth equivalent 66 oz/yd came out without any air voids and thin. (peel-ply and absorbant cloth above and below layup)

I will be doing a true run this weekend in two sessions. 3 sections of 10" x 40". First layup will be (bottom to top) 1 x 6oz high thread count, 1 x 9 oz , 2 x 24 oz (biaxial). 2nd session, same as the first in reverse, for a final 8 layer layup with a 126 oz/yd equivalent

{There are no typos in my post, I have my own language... (dictionary available upon request for an added cost})
[ Parent ]

Re: fiberglass vacuum layup (3.00 / 0) (#6)
by RP on Sat Mar 14, 2009 at 07:36:30 PM MST

I'd suggest adding a bleeder valve to help cool the motor. Usually some (or all) of the air being pulled goes through the motor to cool it. I'm worried that without some kind of "leak" your motor may get damaged.

BTW: another option may be one of those inflator / deflator mini air pumps for air mattresses.

rp

[ Parent ]

Re: fiberglass vacuum layup (3.00 / 0) (#7)
by Rover on Sat Mar 14, 2009 at 08:33:21 PM MST

I just ran on the first of 2 sessions with 4 layups, for 3 1/2 hours at full throttle... no issues. I will be doing another 4 layups per piece tomorrow ( 12 layups).

Inhererent with the using a shop vac, is inherent leakage, from the tubing etc... (mine never broke a sweat) I bought this shopvac 5 years ago a Rigid 9.5 gallon, 3.5 hp .... worked like a champ today with the first 4 layups per piece x 3 pieces.

{There are no typos in my post, I have my own language... (dictionary available upon request for an added cost})
[ Parent ]

fiberglass vacuum layup | 7 comments (7 topical)

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