KingSalomon

What is a #36 hole? It is in the GP UCD 46 manual.

It says to drill #36 holes in the engine mount, and then you tap them with 6-32 threads.

What bit size did you guys use?

Thanks... --Dan

8178

My Feedback: (17)

They are talking about using drill size #36.

KingSalomon

yes but what size is it? is it metric? mine arent labeled with those numbers... i need an equivalent.

bentgear

Comman drill bits are listed in fractional sizes. But, to fill in some of the gaps there are also numbered and letter sized drill bits. A #36 is 0.1065"

7/64 is a little larger and 3/32 is a little smaller.

Ed M.

KingSalomon

Sorry for the noobish question... But thanks for your replies!

Hircflyer

You can get a good numbered drill set at Sears. You should use the correct drill number size drill when you drill a hole to tap threads into, otherwise the threads will not be cut at the right size........if the hole is to big the the screw /bolt could pull out.


Take a look here http://www.biscofl.com/numberdrill.htm

A #36 bit is only .48 cents.......might save your airplane.

76.ta

My Feedback: (39)

To get a #36 hole you must first drill 35 holes then your next one will be #36.
Sorry, I coulden't Help myself

Roy

Scar

My Feedback: (3)

You got correct replies, but I'm going to offer advice, based on my opinion.

Don't thread the mount. Drill it with big enough holes to drop the screws through. Put a locknut on the backside, one of those with the plastic insert, that won't unthread.

Just my opinion. I've done it both ways, and I've had threaded mounts let the bolts back out. I've also seen them crack at the threads. Never had either problem with drilled mounts with locknuts.

Good luck,
Dave Olson

bentgear

Scar, its easy then, just use a 7/64. Run the tap in until just the point protrudes. When you thread the bolt in you have a built in lock nut, then put your washer and locknut on as a safety.

Ed M.

Scar

My Feedback: (3)

Yes, and every thread is a stress concentrator. And the locknut expands the bottom thread - creating tensile stress on the O.D. of the hole, which reduces the fatigue life.

However, if you drill a hole with clearance for the threads, then the external locknut applies compressive stress along the hole, increasing the fatigue life.

I still recommend a clearance hole, and a locknut.

Dave Olson

KingSalomon

Thanks guys, I ended up getting a numbered bit/tap set. I can't but nuts on the underside of the mount because it is tapered so there is not a flat surface for it to sit on.

I want to get a better mount anyway, but I don't know which ones will work with my setup. I have a UCD 3D 46 / SAITO FA-80 combo.

---Dan

Jimmbbo

Dan,

I agree with Dave that a clearance hole and locknuts are easier to drill and less failure prone. On a tapered motor mount beam, I file (or mill) a flat for the nut and washer to sit parallel to the mounting flange surface...


My $.02

Cheers!

Jim

nicadflyer

When I drill the nylon filled motor mounts I use a 3/32 drill and then use a 6-32 socket head machine screw to form the threads. It makes a super tight fit and I have not had any back out due to vibration.

Paul