View Full Version : Belly hole bit question


WadingWill
01-02-2008, 01:31 PM
What size and kind of bit should I use for the belly hole where the swivel comes out? I was told 5/16 forstner bit but can't find this size anywhere. What diameter and type of bits do you guys use?

gldnbear93
01-02-2008, 01:52 PM
forstner or bradpoint bit. If you use a belly grommet, use a bit where you get a nice tight fit for the grommet. If you recess the grommet you will need two different sized bits, one for the grommet shaft and one for the flange.
If you do not use a grommet, start slowly drilling the hole to help avoid tearout.

WadingWill
01-02-2008, 02:01 PM
Generaly, what diameter bits do you use for the belly hole? Or does it vary? I do plan on using 7mm belly grommets.

The Dad Fisherman
01-02-2008, 02:07 PM
Depends on the size of the grommet and the size of the swivel.

Generaly, what diameter bits do you use for the belly hole? Or does it vary? I do plan on using grommets.

WadingWill
01-02-2008, 02:11 PM
Actually I'm going to use the NJtackle belly grommets they are .273" in diameter.

spence
01-02-2008, 02:27 PM
I'd just go online and buy forstners in 1/16 inch increments from 1/4 to 1/2 inches. They aren't that expensive and you will use them all.

-spence

WadingWill
01-02-2008, 02:29 PM
Thankyou, thats what I'll do

WadingWill
01-02-2008, 02:34 PM
Another question off topic. Alot of people recommend 1/8 diameter for through drilling, all the nose grommets I've found are made to fit 3/16 holes. Why do so many recommend the 1/8 diameter will it still fit? Sorry If I'm getting out of hand with the questions but there is so much to learn!!!

ProfessorM
01-02-2008, 02:47 PM
5/32 , .156, is the size nose grommet's most use. M&D's and NJ carry that size. I use 5/32 for the thru hole. For the belly grommet holes I use a Letter I drill which is .272. Makes nice tight hole to put grommet in, no adhesive needed. Sometimes you have to take an exacto knife to run around the hole to get the paint out of the edge but I don't find it a problem.

WadingWill
01-02-2008, 03:08 PM
Thankyou PM

Charleston
01-02-2008, 10:41 PM
The most popular belly gromet is the .343 dia. I use a brad point for that hole.

Ed White
01-06-2008, 06:13 PM
The most popular belly gromet is the .343 dia. I use a brad point for that hole.

11/32" is .343, makes a nice gentle press fit...I've been trying to find a forstner in this size with no luck, only the common fractional sizes.

Ed

mikecc
01-06-2008, 06:16 PM
forstner or bradpoint bit. If you use a belly grommet, use a bit where you get a nice tight fit for the grommet. If you recess the grommet you will need two different sized bits, one for the grommet shaft and one for the flange.
If you do not use a grommet, start slowly drilling the hole to help avoid tearout.



Had these specially turned to match the belly grommet . 1 steps down for the depth of the swivel to meet the thru wire & O.D. Dia of the grommet.While the larger does the outside Dia of the flange of the grommet.
This does everything in 1 step and it is perfectly centered

gldnbear93
01-06-2008, 07:20 PM
Nice!
Where did you get that done?

Had these specially turned to match the belly grommet . 1 steps down for the depth of the swivel to meet the thru wire & O.D. Dia of the grommet.While the larger does the outside Dia of the flange of the grommet.
This does everything in 1 step and it is perfectly centered

mikecc
01-07-2008, 09:28 AM
If there is interest I'll look into having a few made.

eastendlu
01-07-2008, 09:39 AM
Mike that is called a step drill and if you look hard enough you might find them already premade from the factory.;)

ProfessorM
01-07-2008, 10:42 AM
Yup. Lu is right as usual. I prefer a contoured grommet, grommetized as some call it, with the belly hole drilled perpendicular to the surface you are drilling, not drilled with the plug sitting with the centerline perpindicular, thus the grommet fits flush and contours to the radius of the belly, but it is all in what you like the looks of. Mikes way is good too. Life would be boring if we all did it the same way.

splshnplug
01-07-2008, 03:29 PM
hey mike where did you get those. they look nice. you must have connections

numbskull
01-07-2008, 05:46 PM
The better use for those bits is to drill holes for tail weights. You can get them from both Mcmaster and Fuller, though sizes are unlikely to be exactly what you want.

mikecc
01-07-2008, 06:24 PM
hey mike where did you get those. they look nice. you must have connections

Always good to have connections :wave:

Going to WT tomorrow with george.