Reply To: Re-pivot tiny pivot HHEELLPP!!

[Bob Tascione]

This is a good thread!
I’m gonna just fire off a quick response here cuz I’ve got a “honey do” list to take care of for the next couple of hours. If it doesn’t make much sense don’t worry about it. I’ll clean it up a little later tonight. I’ll just respond to a few things you wrote David by pasting quotes and quick responses.

The initial problem was sucessfully drilling through steel with a #80 (.0135) drill bit. This is in itself a difficult machining task. The bits are small, fragile and require small precision tools to hold them properly. I would guess that Digital Tripper spent a lot of frustrating time and went through a fair number of drill bits before giving up.

First off I think your solution was a good one. I was just commenting on the zero chance thing you said which you cleared up.
To this quote,
Yes I agree. Accurately drilling this size hole through steel without the proper tooling would be difficult. For those who may be thinking this would require expensive tooling I’ll throw a little food for thought in here without going off on a tangent and losing the jest of this topic.
Bow, spade drill, staking set. Or bow, spade drill, lathe etc.

“if the #80 hole cannot be achieved then what are the alternatives.”

I suppose brass plates as Paul suggested. Will it work? Not sure cuz I’ve never tried it but sounds feasible and I can’t knock it ’till I’ve tried it. It does seem possible if used only once though. Hope to learn from Jim’s results.

The differences are a larger drill bit can be used reducing the amount of drift

Well, yes if we’re talking about drilling both holes the same depth. Except, we’re talking proportions here just like required blind hole depths for different diameter dowel pins used in our tool making days. I think it would be reasonable to carry over the same fit proportions used for our pivot hole to cap hole. Here’s what I mean. If we assume a 3 to 1 ratio (depth of hole 3 times diameter of plug or pivot) then the depth for the #20 drill (.0135 x 3) would be about .040. If we give the cap hole a diameter of say 1/16″ (.0625 x 3) then we’re looking at a required depth of about 3/16 (.187). So as I said earlier: ‘pretty much equals’. Where I must give some lee way here is that the pressure placed on the 1/16th. drill would definitely be easier to control than on the #20 and since pressure or feed plays such a big role in drill deflection the chances of drift would be greater with the smaller #20 if some type of control isn’t available. But…there is a very simple way to control the pressure when using a staking set and it’s free if you have a few weak old compression springs laying around. Hint: ball point pen pulled apart, remove ink cartage, place over punch (may need to cut plastic back a little) then press just enough to engage spring pressure, activate bow and watch out for hot flying chips…well slight exaggeration I suppose but it does work (wonder if the big Ber has these and what they go for). There’s a little more to this than I’m explaining here as you’re not actually turning the punch but rather a small homemade drill holder with a pulley, and a drill inserted. This whole assembly sits between the punch and work piece. Very simple to make, simple to use, accurate and fun!
We’re kinda splitting hairs with all of this anyway since we’ve already concluded that the pivots for both methods can be dressed if needed. It’s fun though…got to have fun!

I have read articles on both sides of the issue on whether to re-pivot or make a new staff.

Yes lot’s of debate on this subject. Whether it’s good practice or not I don’t know. I personally don’t like to pivot staffs and would rather just make a new one as Paul suggests. It’s a matter of preference though and I don’t have an opinion either way on how someone wants to do it. Arbors are a different story for me though as quite often there’s a pinion that will need to be cut making the whole arbor making process very time consuming. At least it takes me a long time.

I’ve probably skipped some stuff here but getting the evil eye from my guests so got to go.

Enjoy for now and again good thread!

Bob