Thumb Joint buildup

[Washout]

Since I started bowling I have noticed that the inside joint where the thumb meets the hand that I have some build up on the bone it seems like. There is also a callus buildup over this joint. I am curious if this is normal for bowlers. There isn't really any pain, unless I overdo it and bowl like 6 practice games in a row.

[Greenday]

What kind of thumbhole do you have? Oval or circle? Thumb slug or no? Squeezing the ball too hard?

I had a tumor in my thumb from bowling when I started out in high school. Completely benign, just formed to protect the nerve in my thumb. Switched to thumb slugs, ovaled it out, beveled nicely. No more problems.

[Washout]

Drilled circle. I have thought of thumb slugs though. I have been concentrating hard on keeping my hand behind the ball to reduce the stress on my thumb. I will look into thumb slugs however. The hole just needs to be drilled bigger for those correct?

[Greenday]

Drilled circle. I have thought of thumb slugs though. I have been concentrating hard on keeping my hand behind the ball to reduce the stress on my thumb. I will look into thumb slugs however. The hole just needs to be drilled bigger for those correct?

Well, basically they drill a hole, put the slug in, then drill a hole in the slug. It's a smoother surface so it's less friction on your thumb. And then you can bevel it so it's even smooth along the lip.

[Washout]

that actually sounds exactly like what I need, the callus buildup in that spot seems like a dead giveaway that there is too much friction...my new ball(Brutal Nightmare) coverstock seems more forgiving than my C-System

[bowl1820]

Given if your getting a callous at the base of your thumb (palm side) sounds like a possible fit problem. So you should have your grip checked.

http://www.jayhawkbowling.com/Pro_s_Corner/Fitting_Tips/fig6.jpg
Possible causes:

1-Span Too Short or Too Long
2-Hole Needs More Bevel
3-Hole Too Big

[Washout]

Yeah I am going into my pro shop tomorrow and getting this looked at. My thumb is a bit loose, nothing drastic, but i think if i go with a slug and a little bit smaller drill it should fix the issue.

thanks for the advice