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Pilot hole too big

Old 03-29-2007, 02:32 AM
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Zipperneck
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Default Pilot hole too big

Ahhhhhh - I still can't believe I did it!

I wanted to drill a pilot hole in the landing gear rail to ensure that the wood would not split when I screwed the landing gear's mech retract mechanism in.

I'm using four 3mm screws to hold in each retract mechanism and like a TOTAL IDIOT, I drilled 2mm pilot holes. Ahhhh (slamming head on keyboard). While the screws go in nicely, I fear that if I torque them down I'm going to strip out the holes - not to mention what a rough landing would do to the installation.

QUESTION:
Is there any product/glue/lock-tite-type product for wood that I can use to ensure a tight fit? A friend suggested a polyurethane glue.

There is no real way to replace the rail without ripping everything apart and I can't beef anything up as everything is perfectly adjusted. Ahhhhh.

Any help would be appreciated.

Thanks
Zip
Old 03-29-2007, 05:09 AM
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MILDBILL-RCU
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Default RE: Pilot hole too big

You could put a glue of some sort in the holes to kind-a fill some of the extra space, then put screws in & they "should" do OK. If it were mine, I would drill the hole to the largest size that the beams will allow before getting to the edge, then make hard wood dowels that size & epozy them into the holes flush with the surface. After its all dry, redrill your holes, but with the proper drill & all will be fine. Please dont ask, how I know this, or how many times I still goof after 25+ years doing this. lol,
Old 03-29-2007, 05:15 AM
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jetmech05
 
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Default RE: Pilot hole too big

Well its no big deal.....after all when you're finished you're goinng to have a 3 mm hole. I assume you're using wood screws not machine screws. go ahead and torque in the screws. I didn't say over torque in the screws. now if you're still worried about the screw holes remove the screws and drop in a couple of drops of thin ca glue and let dry. This will reinforce the threads cut by the screws.
Or step up the screws 1 size, or drill all the way through get longer screws and secure with a blind nut or lock nut. Kinda hard to tell whats what without a pic...
good luck
Old 03-29-2007, 05:18 AM
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Zipperneck
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Default RE: Pilot hole too big

Yes, that is a good idea. However, before going the dowel route, I think I may just try some of the polyurethane glue that my friend suggested. The screws do have some "bite" to them but I just think that it may be a bit weak.

The mechanisms fit very snuggly into their housing, so I don't think that there should be any play to work on the screws. If needed, I could drill them out and put in some dowels... or use just a bigger screw, I suppose, like a 3.5mm screw. Hmm, I'll look into that as well.

I still can't believe I did that. Amazing.

Thanks for your input!

Zipperneck
Old 03-29-2007, 07:31 AM
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vicman
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Default RE: Pilot hole too big

I would use a diffrent glue than Polyurethane. You are looking to ensure the screw gets enough bite not fill space with a bond. Use epoxy or CA as mentioned earlier. I use gorrilla glue all over the plane but this is not a good application for it.
If you go the dowel route it will work fine to hold the dowel in.
Old 03-29-2007, 07:54 AM
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MinnFlyer
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Default RE: Pilot hole too big

Remove the screws,

Put thin CA into each hole

Let sit for 30 minutes

Replace the screws and tighten them good.

If they pop loose, remove them again and just fill the holes with 30- minute epoxy and let sit for 24 hrs. Then re-drill with a smaller pilot drill
Old 03-29-2007, 08:05 AM
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Zipperneck
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Default RE: Pilot hole too big

OK, sounds good. I'll use the CA method, then if that doesn't work, I can alway use the dowel or epoxy method.

Thanks for all your help!

Zipperneck
Old 03-29-2007, 09:50 AM
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Robert Bauer
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Default RE: Pilot hole too big

Drill a hole in some scrap. fill hole with baking soda. add several drops of THIN CA Try this method to see if you like it. It will be stronger than the wood. Don't breath the fumes when you add the CA. I think you will find this method usefull for many types of repairs. Remember it doesn' sandpaper well .
Old 03-29-2007, 10:21 AM
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Steve Collins
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Default RE: Pilot hole too big

Use 4-40 size threaded brass inserts and use 4-40 bolts to hold your retract down. I doubt if you can find the brass inserts in metric sizes.

I always use the brass inserts for holding down retracts and on the firewall for engine mounts as well. Far better than blind nuts.
Old 03-29-2007, 10:31 AM
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Zipperneck
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Default RE: Pilot hole too big

Yeah, I had thought about that solution as well but I am not sure that the rails would have enough "meat" on them to adaquately hold the insert. And yes, I have a source for 3 and 4mm threaded inserts here in France....

Thanks,
Zipperneck
Old 03-29-2007, 01:10 PM
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mschneider2005
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Default RE: Pilot hole too big

I have coated the screw with vasaline and filled the hole with 6 minute epoxy and lots of mircobaloons. I put the epoxy down the hole and put in the screw. The epoxy won't stick to the grease and the screw comes right out when the epoxy cures. Your left with hard, new theads. Try it on a piece of scrap if you like. Works great on my models and my 49 year old corvette door panels haven't fallen off since!

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