Tapering Holes

[Ga Red]

How do yall taper the hole in the bolster for a front pin in a pocket knife.

[jerryd6818]

Welcome to AAPK.

I'm not a knife mechanic but I would think a light touch with a taper ball end mill might do the trick. Others may use different approaches to the task. There's one thing AAPK is not short on and that's opinions. Check back.

taper-ball-end-mill-cnc-tool--router-bit--end-mill--for-cutting-advertise-products-MDF--R0_5-0_75-1.jpg (16 KiB) Viewed 2423 times

Or a light touch with a Tapered Hole Reamer.

Tapered Hole Reamer.jpg (12.54 KiB) Viewed 2421 times

Or the right size tapered broach. These are way too big but they make smaller ones. In fact if you give me the size of the hole, I may have one in the garage I'd send to you.

[americanedgetech]

I hope some mechanics will chime in as to their own methods. The most common tool I have seen thru research is a tapered reamer. I personally believe these remove a lot more material than you need to remove for a secure fit, and I have been looking for an alternative method/tool.

Like I said I hope others chime in because that tapered broach is what I've been looking for, I just never thought of it.
I think it may be the perfect tool JerryD! All you need is a few thousandths taper on each side (0.02.-0.03) for a secure "lock".
Thanks for posting this.

[jerryd6818]

Ken, I have a box of broaches of various sizes with several duplicates. If I don't forget, I'll go out to the garage tomorrow and see if I have any that are the appropriate size. Sure could use the pin size.

[btrwtr]

I have never tapered a pivot pin hole. Peening the pin flares and expands the end to fill the hole completely and secure the pin tightly.

[Ga Red]

I need it for 3/32 and 1/8 inch holes

[americanedgetech]

Ken, I have a box of broaches of various sizes with several duplicates. If I don't forget, I'll go out to the garage tomorrow and see if I have any that are the appropriate size. Sure could use the pin size.

I appreciate that JerryD but no need. I'm not set up yet, and broaches are cheap enough for me to get thru my normal suppliers.
I realize that they are made for press cutting but I'm sure they will work.

Wayne,
I have learned that most knives do not use tapers on the bolsters, and from a manufacturing stand point I understand why.
From a mechanical perspective I see the benefit in tapering, and it is an approach I prefer to use when, and where I can.

While I do not plan to use most of the knives I will be repairing or rebuilding, I will be selling them as users or with the intent that they can be used, and I would sure hate to have pins slip or have blade wobble come into play on anything I worked on.
I believe that the one extra step of tapering a bolster is a virtual guarantee that this one potential problem can be avoided.
I know that most knives work just fine for decades with straight pins but I've broken a LOT of knives in my time, and blade wobble is the first thing that happens to mine.
Just my thoughts.

[jerryd6818]

I realize that they are made for press cutting but I'm sure they will work.

Don't know how you're applying "press cutting" but broaches are designed for torsional cutting. Stick it in the hole, apply appropriate pressure and twist. They're actually more for tapered pins but I think they will work just fine to make a slight conical shape at the top of a drilled pin hole. Improvise, adapt and overcome.

[americanedgetech]

I realize that they are made for press cutting but I'm sure they will work.

Don't know how you're applying "press cutting" but broaches are designed for torsional cutting. Stick it in the hole, apply appropriate pressure and twist. They're actually more for tapered pins but I think they will work just fine to make a slight conical shape at the top of a drilled pin hole. Improvise, adapt and overcome.

"Stick it in the hole, apply appropriate pressure and twist."

That would be what I meant by "press cutting"
My entire life has been about improvising so that I can adapt to what I've had to overcome!
We're on the same page