drill bits for taping new threads

[kcombs9]

what drill bit is needed for 10/32 heli coil kit? (I'm sure the kit tells me but it is being shipped to me and want to find the bit before it shows up to cut down on wait)

and what size tap/ drill bit do I need for an LPR (rockler)?

[Tunaman]

what drill bit is needed for 10/32 heli coil kit? (I'm sure the kit tells me but it is being shipped to me and want to find the bit before it shows up to cut down on wait)

and what size tap/ drill bit do I need for an LPR (rockler)?

13/64th's for the 10/32 tap and 1/8-27npt is the tap for the LPR

[Ando]

If you purchased a full kit. They usually come with the bit, install tool, inserts and tap.

[Pneumagger]

Size R (.339") pilot drill for the 1/8"-27 NPT tap.

Don't helicoil kits usually come supplied with the appropriate repair drill and tap?
Unles you order only the inserts.

[kcombs9]

Size R (.339") pilot drill for the 1/8"-27 NPT tap.

Don't helicoil kits usually come supplied with the appropriate repair drill and tap?
Unles you order only the inserts.

or will 7/16 work? that's the size I saw stamped on the 1/8" - 27 NPT tap.

[XM15]

No 7/16 is .437 not even close to a a letter R drill. You could use a 11/32 drill if you don't have a letter R drill its only .005 bigger.

[Pneumagger]

Everything I've always seen reccomends size R as the pilot hole and I've always used it with success.
Here's one reference: http://www.engineersedge.com/manufac...rill-chart.htm

The major OD of the hole is listed at .405" in my references... which is considerably smaller than 7/16"
I would think if you drill a 7/16" that the tap would fall straight through.
I just measured the threads on a macro elbow and the widest dimension at the base of the threads is .410"

Are you sure 7/16" (if it's printed on the tap itself) isn't the shank diameter (chuck size)?
Try 11/32" if you really want ot use a fractional drill size - that should work OK too.

[kcombs9]

I must have rear the tap wrong, it was one I saw online. maybe they used a generic picture.

How long do the Size R bits come I need it longer then 4-1/2", close to 8" id guess have to measure then I get home.

[Pneumagger]

McMaster has 6.5" Size R for $12 and 12" Size R for about $20
They also have an 8" 11/32 bit for $13

Just out of curiosity... why in the world do you need an 8" 1/8 NPT pilot hole?

[kcombs9]

McMaster has 6.5" Size R for $12 and 12" Size R for about $20
They also have an 8" 11/32 bit for $13

Just out of curiosity... why in the world do you need an 8" 1/8 NPT pilot hole?

8" is just a rough guess, I need to tap for the LPR from above not below. So I need the bit to go through the inside of the frame.

[Pneumagger]

You can drill the through hole from the bottom of the frame... it's just a straight hole straight through the frame so any size bit should work. Although the tap itself will have to be pretty long to reach through the frame. Tap the hole deep enough to get the end of the LPR threads about .050 from the bottom of the frame when tight. This will take some incremental trial and error fitting. Then a regular oring will be sufficiently squished between an ASA and the LPR.

[kcombs9]

I want to mount the LPR at an Angle, I'm afraid it wont seal with the asa so I planed on drilling at an angle not going all the way through, then drill up from below with a smaller drill bit so I get flow and a good seal.

[Pneumagger]

Sounds like a slick set up.

Tip: when drilling at an angle or a round part, use an endmill slightly smaller than the objective hole diameter to face off a flat spot perpendicular to the drill. This will keep the drill normal to the surface so it doesn't wander/flex off center. In this case, a .375 endmill should make a nice start because the drill is .339 and the finished hole major OD is .405

Have fun and be sure to post results!

[kcombs9]

where can I get an end mill bit that long though, and sounds spendy

[Pneumagger]

Keep in mind, you can also flatten the profile from the side.

You don't have to do it... but you should go slow if not. Make sure bit isn't flexing or wandering. Light pressure and a drill press will be highly reccomended at a minimum.