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Mcmaster Seal Compression

Bill.Peyton

Bill.Peyton

Well Known Member
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I just finished the first trial of the door with the Mcmaster 1120A411 seal installed. It is extremely difficult to get the door to latch and is slightly deforming the door around the middle. I planned for the seal to be 3/4 to nearly 7/8 compressed and I am thinking that may be too much. What is the consenses for those who have working doors regarding the gap from the door to the frame? Would 50% seal compression provide sufficient seal and help this situation?
Bill
 
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Bill,

I ran a 1/4" reveal between the door and the cabin lip for the 3/8 bulb on the seal. I originally had 3/16" and it was too tight so I opened it up to 1/4. My door is still really tight but easy to close and no leaks. I have the hinges covered too on the inside for the seal.
 
My $0.02

I've got mine installed but not flying. My seals compress pretty far, but the door doesn't deform at all and you don't (and you shouldn't) have to really work to close the door. My suspicion is that you might have too little gap for the seal at the top, and that causes an exaggeration of the effect when you try to close and latch. Ask me how I know. I started at the top sanding down the lip on the cabin top, using a few short pieces of the seal to test the closing on, until the fit was about right and I could close and latch the door without effort. Then I worked down the fore and aft sides of the door doing the same. The top needed the most work on mine. I guess I would say to do it that way until the door comes to rest at a point where the pins will engage without having to push it in at all. The amount the door pins pull the door in should be all that the seals compress. I'm pretty happy with mine, but again, no flying experience.
 
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I'm very pleased with our McMaster seals. The door is a little stiff to close but not enough to call it difficult. I would doubt the seal compresses 1/8". I'm amaised at how dight it is. On several occasions going to Sun n Fun, I ran my hand arround the perimeter and was unable to detect any draft. I think we may have some air coming from the rear bulkhead.
I would say you only want enough compression to seal the door and not create a load on the attachments.
Ron
 
HANDY TIP

Folks, get a can of Silicone Spray and liberally coat all the mating surfaces.

Close the door and let it sit for a few days while you, go to work, do some other tasks etc.

The type of seal we used the door would not come within an inch or two of closing until we realised it grips at the top and will not pull down because the door is gripping the top section.

Next Handy tip

If you have not painted your plane yet....silicone spray will cause you paint adhesion trouble unless each molecule is carefully cleaned off. So do this post painting perhaps or be careful with the spray. Apply with a rag maybe? but it eventually spreads so paint first seal later.
 
Maybe to verify that this is the issue I will use grease or vaseline instead of silicone to temporarily try the fit. Assuming that works, it will be lubed after it is painted
 
I just measured several spots on my door clearance. I am as small as .25 at the top and .277 everywhere else. I should have checked the seal first and kept sanding. The seal uncompressed is .41 and totally compressed it is .16. It appears that nominal compression to yield good surface contact needs to be around .3 to .32. Which sounds like what you have Wayne.
 
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I used a steel rule and marked cabin cover flange 5/16"

from interior surface of door to give me some points to grind to. Of course this is after getting doors fit up the way I wanted them or close anyway. On top it would have meant grinding away all parent composite and I did not want to do that so I went 1/4" or slightly under on top. I rechecked door closures today and it is approximately 1/4" of being closed when let down. No vaseline, silicone or anything else on my seals. I then built up edge back to approx 1/4" thickness all the way around. There are some areas that are thicker and slightly angled on forward edge. Once the seal was cut and fit nicely I then finished door latchs/Sean's kit and fine tuned clearances. Touched up interior paint. Installed seal with thin layer of proseal on edge. Heavier on top to keep water from going under seal. Form a fillet with your finger on top and around remainder if there is any that squishes out. I then clamped or taped as needed for 24 hrs. The seal came up about 1/2" short on both sides so I had to insert a short piece with proseal. I am assuming with the proseal it "lubricated" the seal and allowed it to seat over the flange better. So you may want to ensure your seal is seated better than mine the first time. No biggie though.

I have been on this section for about 6 weeks and probably 125+ hrs. I applied exopy to pinholes/filler today for some protection until I get it professionally painted. I am through for now and working on panel some more before installing on gear. What a miserably long section. Someone at Van's fiberglass and window vendor really needs to take a look at the fitting problems of this cabin cover/doors/windows. Whether you use Van's seals or not that top door flange on the cabin cover is too high, so no wonder many doors cannot be closed easily. Window recesses are not 1/8" like they should be. Scribe marks on doors were within 1/8" but cabin scribes were way off in places. Just measure twice, cut once and be prepared for lots of messy work.
 
Door fit

I totally agree with Wayne on this. I also think that Van's should reconsider who makes there fiberglass and composite parts. The cabin top process is awful. I now know why Mooney and Piper only put a door on one side of the airplane. It is just to much work to do ! There was one composite part on the RV-10 that fit pretty good, the cowling. Unlike my RV-6 cowling that I had to cut the front off and start over. If the mold for the part is wrong the part will not fit. Lets look on the bright side. At least now we know that we really do not want to build a composite airplane. LOL!
 
Word of wisdom for you all.....:D

You would think having built our -10 under the supervission of a 10+ RV builder and who also built one complete before and helped another finnish of one we would have benefitted from the experience of others.

Well this is what we learned. No matter how well you think you have accurately measured here sealled there.....until you fly in rain, and at time rain that hard it peels your decals off, you will never know.

We now have cabin doors that are leak free. Yep, can fly all day in rain and we stay dry. We can wash the thing with a fire hose. No water in. But it was a massive trial and error (drenching) process.

I can not even begin to describe it.

Bottom line is until you are finished and flying and prepared to have hours of frustration you will never know.

Good Luck! :)
 
Wayne, thanks for the info. I spent the whole day doing exactly what you described. I sanded the gap to .280" all the way around, and the fit is good. I had already added glass on the inside to beef up the lip. I also added 3-4 layers of 6 oz. cloth to both sides of the doors on the side to account for the structure that was removed to accomodate the seals. I will have to add some additional glass on the inside again to account for what I took off on the outside today. My doors now close ok and will probably get better with time. I have replaced door seals before on Pipers and Beech and it usually takes a couple of months to loosen up.
I agree with you on the Vans quality issues. There is no reason that the tolerances and workmanship could not be improved. I started the cabin cover 6 weeks ago, I have been working 5 days a week with my Dad and we still have plenty left to do. I need to seal the fiberglass, paint the doors and interior of the cabin cover, install the overhead and headliner. I will be lucky to get this done in the next 3 weeks.
 
Remember it will be worth it in the end...

No problem on this sb meeting that 51% is there:D. 1,369 hrs as of last night.

I have printed off 8.5 x 11 pages of many of the places we want to fly and posted them on the shop wall. Most are showing "mvfr" due to all of the fg dust on them. Keeps me motivated though. Lots of little trips to make with the local guys too...Ted, Bob, Geoff, Alan, Jim, Bill and many others.

Bill, I forgot to mention the reinforcing. I built up the inside corners of the corner post front and back about 1/4"-3/8". Keep at it, its all downhill once that is done. At least that is what I am telling myself.
 
Wayne,
One day I will have to fly over and see your progress. You look to be a few steps in front of me. It could save me some time! I hope to get the overhead in and clean up and primer the inside this week. Once you install the cabin cover on the fuse permanently, were you planning on glassing all of the pull rivets and covering the joint between the fuse and cover, or just let the joint show?
Bill
 
In defense of Van's fiberglass parts,,,,I find the quality to be very good. Try building this stuff from scratch like we did on the Cozy MKIV.;) I am also working on my doors right now and have found the scribes to be right on for the transparencies and very close on the glass parts. It took me two days of work to fit the canopy to the fuselage and drill it and that included time to remove it afterward and form and lay-up an overhead console. The windscreen and side windows took 1.5 hours to fit final sand the edges. I must be doing something wrong because I am enjoying his part of the build so much.:D It really looks like a plane now!
 
9GT, I admire composite builders...now that I have worked with both

I would imagine that it takes more time to build fg vs metal. I was thinking at one time of building a 4 place composite. I'm glad I changed my mind. They are pretty and sleek though.

Bill, you are welcome anytime. I can pick you up at M97, HTS(Class D), DWU, HTW or PMH. All are 30-60 minutes from the house, so take your pic. I am going to try to pay some of you guys a visit this summer too.

Yes, After filling joints with micro/epoxy, I layed one layer of 3 oz cloth strips over all window and cabin cover joints for cosmetics not as much for strength. Then applied more filler to blend in. It is not a show plane for me...just a good x-c machine for the four of us(two kids 11 & 8). Gray painted interior, gray cloth seats, gray Crow seat belts and ifr panel in process for future ticket. I do admire anyones show plane too and wish I had the skills, time and money to do such a project but I don't. I am a self employed hvac guy. It is all I can do right now to juggle family, business and the build.
 
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