Riff, I understand the reasons for debulking and degassing and if that’s how you roll then I’m not going to stop you. True the air will escape quickly but if you can easily avoid it why wouldn’t you? And definitely put the resin container below the part.
cs900, you are not using prepreg so unless your laminate is very thick a cyclic debulking at the end will be fine.
the laminate will likely be as close to 1/4" as we can get, but for right now we are just trying to get the process consistent.
edit* also I’ve got my system so that it only looses 3"Hg in 10 min, is this acceptable?
nono, only for prepreg do you do that. Dry fabric, you CAN lay up everything, and then just pull and release vacuum several times. but that is only when you know how your part, resin, and flow behaves.
When you say system, does this include the vacuum bag (mold, tape, bag, connections) or just the pump/trap/lines you have shown in your pictures?
If it’s a small leak in the latter, it’s no big deal, but it will make it much harder to find leaks in the bag. Small is relative; the larger your volume of tubing, reservoir, trap, etc, the slower the pressure will drop for the same size leak.
You cannot have any leaks in the bag, or you will introduce air bubbles, and possibly an incomplete infusion. Check your pleats, corners, tubing entry/exit points, pinholes in the bag, and porosity in the mold for leaks.
Is that the check valve on the outlet side of the pump?
that does not include the bag. it’s just the parts shown, and yes the check valve is installed in that picture.
you’ve actually kind of hit on my next question. The tubing inlet and outlet, how do you guys do this. So far we have just been sticking the tubes in the bag and putting tape around them to seal them, but this has been somewhat problematic. I know they make aluminum fittings you can use, but we’re kind of on a tight budget. That being said, if anyone has a cut-away picture of one, or possibly a picture with all the components laid out, I do have the equipment to actually make them myself. Or if anyone knows of a good reliable method, i’m all “ears”.
OK, so why is the check valve on the exhaust port? If you think the pump is leaking, shouldn’t you put the check valve on the inlet side? Maybe I’m missing something.
You don’t need the fancy connector for tubing. I was taught to wrap a strip of tape around the tubing, and stick that on the perimeter tape or in a pleat. Use some more tape along the tube to make sure the tubing doesn’t twist or bend itself loose, if you have stiffer tubing.
I’ve used the aluminum connectors before, but stopped when i started doing infusion so I didn’t wreck them if the resin gets in the vacuum tube.
This was mentioned in another thread, but Freeman Supply has some good videos on bagging and layups in general. There’s nothing specific to infusion, but is helpful to see some stuff in action. You’ll have to sign up for their newsletter to access most videos.
If you haven’t already, search around for the other infusion threads to see some setups and results. There’s also some video on youtube.
air is leaking into the exhaust port when the pump is not on. that’s why the check valve is there. although I could put it on the other side and not have to worry about the pump at all.
yeah, we are using hard line, and it seems that whenever we bump the darn thing it springs a leak at the seam.
run the pump all the time, your problems will be solved 
We use tacky tape around areas that don’t seal well. some of our buckets have had the LDPE tubing cut off the barb fittings with a blade so often, the barb is scored, and doesn’t seal well. Some are just old anyway, and people throw tacky tape around the fittings. normally works.
but really, have the bag, gage, bucket, pump in that order. Clamp between the bucket and pump, and then use the gage on the bucket to see if their is a leak. If the leak is POST bag, really it’s ok. Just means you aren’t pulling a FULL vacuum, and might wear out your pump sooner.
The bag is the main thing to have no leaks.
yeah, we’ve been running the pump for 4-5 hours until the resin has gelled quite well. after that we clamp off the vac tube to the bag and let it sit 4-5 hours more.
we made another laminate today, and i made yet another rookie mistake. i completely forgot to put any type of breather material around the vac inlet and the bag sucked right down over it making it nearly impossible for any air or resin to flow. oh well, live and learn. that’s why we’re doing test runs before making any actual test samples.
Just wrap and tape a little fiberglass to the end of the vac line.
hey guys, i’m back…
So we’ve been making samples to test for the last few weeks and we keep getting voids in the resin around the weave intersections. I’ve attached a picture trying to show what I’m referring to. I’m unsure if this is just on the bottom surface or if it is like this threw out the laminate. the top surface where the peel ply sits seems to be ok.
click on it to see the full size…
I’ve tried several different things trying to eliminate this. I de-gass the resin prior to infusion. I de-bulk the layers before infusion. I’ve tried pulling full vacuum (26"Hg) and partial vacuum (down to 20"Hg) during infusion. I check for leaks in the bag, and as far as I can tell I have none.
I’m a little stupefied as to what could be causing this. Any suggestions?
you should read “my infusion nightmare” post which is a few post down.
So it sounds like i’m also excessively draining the resin from the part by running the pump for too long after the part was infused?
is this an accurate description of what I might be doing wrong?
cs900 I had same problem. It is excessive draining. Maybe leaving vac line open for cure is working for someone but not for me. You need resin with short geltime, or you will drain the resin out after clamping inlet tube (my problem - 8hour geltime). I tell you what I do. Clamp feed line after you have about inch of vacuum tube filled with resin. Than clamp also vacuum tube in that area filled with epoxy. Clear outside of inlet tube from resin with paper towel. Connect vacuum source to inlet tube with fitting or better just use bigger tube which I.D. is same as inlet tube O.D. and seal with tape. You can pull vacuum, than carefully unclamp inlet tube to drain some resin around feed port. You dont have to use max. vacuum to that and be careful with it because you can easily drain out part and create dry spots.
Just had an idea that has proved well here.
In your injection line, add 2 T fittings, with a SMALL diameter (1/16-3/16 ID), in bypass fashion. After part is almost filled, clamp the larger main inlet tube, and let the smaller one open…
OR, just clamp the big tube not all the way, and leave a small opening. THis way, resin will fill the part while gelling, BUT the pressure will decrease in the part. You won’t have a full 28" all the way through (never do anyway), but you won’t have 0" on one side, and 28 on the other.
Or you can reduce vacuum after clamping inlet. I tried it, I let it cure with vacuum line opened at -0,3atm but there was still problem with excessive draining. But it can work for shorter geltime resins.