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View Full Version : Screwdriver Sizing Question


napp
December 11, 2010, 01:38 PM
Made an interesting discovery yesterday when disassembling my Pietta 1860 Colt. My set of screwdrivers was purchased from Brownell some years ago. It is the set that has interchangeable bits of various sizes. Until yesterday, I had never had a problem with finding the perfect sized tip for any of my guns.

The problem I encountered yesterday was when selecting a tip that was thin enough to fit into the slot cut into the screw head, the tip was not long enough to fill the slot in the screw from end to end. Conversely, if I tried to choose a tip that was longer, the tip was too thick to fit in the slot.

Is it a characteristic of the Italian manufactured guns to cut thinner slots into the screw heads? I don't want to take the grinder to my screwdriver tips; because they always fit perfectly into the screws used in all my other guns.

junkman_01
December 11, 2010, 01:45 PM
It seems to be a problem with the Italian guns. I find the same thing, so I grind the tips to fit. The alternative is to widen the slot in the screw (which I have also done at times).

wogpotter
December 11, 2010, 04:04 PM
Same here I guess that's why there are "special" screwdrivers, but no special bits advertised for these guns.

mykeal
December 11, 2010, 04:13 PM
????
I have the Brownell's set and have had no problem fitting screws on Uberti and Pietta guns of all ages. I don't understand trying to fit both the width and length of the slot - what's wrong with the blade being a few thousandths shorter than the screw slot?

mrappe
December 11, 2010, 04:21 PM
Brownells has a set of "thin bits" that is what I use.


http://www.brownells.com/.aspx/pid=425/Product/MAGNA_TIP_reg__THIN_BIT_SET

junkman_01
December 11, 2010, 04:43 PM
That certainly looks like it fills the bill.

bedbugbilly
December 11, 2010, 08:26 PM
Boy - you guys are sure fussy! A gun doesn't have "character" unless the screw slots are all "buggered" up! That's why I use phillips heads on my slotted screws and a 10 pound sledge to put the barrel wedge back in . . . I missed the wedge and hit the barrel one time . . . . but, hey . . . I needed a pistol that would shoot around corners . . . :D

It's hard to believe, but I actually found a set of screwdrivers at Lowes one time that had three hollow ground straight blade drivers that fit and worked great. It was a number of years ago and I don't remember the brand of them but I do remember I had to buy a whole set of about eight screwdrivers to get the three I wanted. One of them is perfect for grip screws and I keep it just for that - I hate seeing a nice set of grips with a messed up screw head! That was alright though - just threw the others in my tool box as you can never have enough screwdrivers. If I remember correctly, the price wasn't too bad either - somewhere around $15.00 or so. I'd give the brand but unfortunately, I'm in AZ for the winter and they are in my bench drawer back in MI.

Ideal Tool
December 15, 2010, 02:00 AM
"Whats wrong with blade being a few thou. shorter than screw slot?" If your working on a High $$ gun it matters! The portion of the blade that starts to taper out to shank dia. is going to contact the very edge of slot & this tiny area will be taking all the torque, resulting in a nice unsightly burr.

mykeal
December 15, 2010, 07:12 AM
I think you completely misunderstood my question. The issue is not the taper of the blade - it's not tapered on a good set of hollow ground gunsmith's bits, and if the proper size is selected it will fit the slot completely from top to bottom and along the entire length of the blade. There will be no 'tiny area at the edge of the slot'. If you're using tapered drivers you're using the wrong tool.

I'm talking about the long dimension of the blade fitting the length of the slot. It doesn't matter if that's a few thousandths short.

Doc Hoy
December 15, 2010, 07:52 AM
I wish I could speak with more authority on this topic. But not knowing what I am talking about never inhibited me from talking.

Some time ago I bought a set of hollow ground screwdrivers with wooden handles. These drivers are still available at a relatively low price. I let them get away because I thought the quality of the metal in the tip was not up to par. They were hollow ground as I said and there were probably four different sizes in the set, maybe more.

I looked at a set of Smith and Wesson for about forty bucks and though I did not buy them or try them they appeared not to provide much of an advantage.

I have been through the Brownell’s and other high end screwdriver decisions without making the commitment. I would want to play with a set or at least handle one before taking the financial plunge.

My Chapman set does not have the right size bits to cover everything I need and the shape of the bit, although hollow ground was machined at a small radius which means that the part of the tip which engages the slot has already begun to transition to the part of the arch which does not meet the slot at a parallel (If you know what I mean). I used Chapman sets which I was in the Navy and I can say that I broke some Chapman bits on especially tight screws.

I have two sets which I like some aspects of. I have a set from Workforce (Ten bucks at Home Depot) which has excellent bits which are hollow ground with a good gradual transition and good metal. The handle is a ratchet job which is terrible. I also have a Husky set (Also from Home Depot) which has a non-ratchet handle which I like. There are only two sizes of bit but I find that these work good enough that only two sizes are needed for most of the screws I work on.

I think that an important aspect of the screw driver has less to do with the tip and more to do with the shape of the handle and the length of the shank. Obviously you have got to have hollow ground drivers but you also have to have good control of the tool in order to reduce the chance of slipping. I am inclined to go along with Mykeal on this particular point. My sense is that the only time I am comfortable using a long shank driver is when the screw is not very tight. If the screw is tight I want a short shank with a Tee handle. (I only have one Tee handle and it is a ratchet from Excelite which I don’t like at all.) I also do not like the idea of changing bits. When I get more time (maybe this winter) I am going to put some thought into a screwdriver which is more to my liking.

I do understand that my screwdriver is probably only good for me. I also know that there are high end sets out there that folks really love.

madcratebuilder
December 15, 2010, 08:28 AM
Midway sells the "Wheeler" brand of driver tips. Dozens of sizes, if you have a odd screw get one as close as you can then grind for that perfect fit.

I run across a screw every now and then that I have to make a bit for.
http://i32.photobucket.com/albums/d37/madcratebuilder/PICT0030.jpg

Ideal Tool
December 15, 2010, 06:03 PM
Hello, mykeal, What I ment was, even if a screwdriver is hollow ground, the tapered portion of the RADIUS must not contact the top edge of screw slot, otherwise you would have the same effect as using a tapered driver...burr. To avoid this, just be sure the straight or parallel portion of blade when bottomed in slot is taller that slot depth.

mykeal
December 16, 2010, 08:35 AM
I understand what you meant, and it should be clear from my second post that we agree on that point: the portion of the blade that engages the slot must have parallel sides and fit the dimension across the slot.

I'm still not sure you understood my original point, however.

The OP complained that the bits in his Magna-tip set did not match the screw slots in both width across the slot and length along the slot:
The problem I encountered yesterday was when selecting a tip that was thin enough to fit into the slot cut into the screw head, the tip was not long enough to fill the slot in the screw from end to end. Conversely, if I tried to choose a tip that was longer, the tip was too thick to fit in the slot.
My advice is that matching the length along the slot is not necessary.

junkman_01
December 16, 2010, 08:48 AM
The length along the slot is a matter of leverage. The longer the bit the more leverage it can put on the screw head. A little bit shorter will not make that much difference, a lot shorter could raise a distortion in the screw slot.

Doc Hoy
December 16, 2010, 09:19 AM
.....The screw is tight I would agree that the bits should be nearly as long as the screwhead is wide. I would say that in these cases, the additional mechanical advantage would reduce the likelyhood of breaking the bit or damaging the head of the screw.

In my experience, I only encounter tight screws rarely and in those cases I am almost completely accepting of the fact that the screw head will not come out of the encounter unscathed. Don't tell me I need to be more careful. I know what I am doing with a screwdriver.

I have two bit sizes that work on just about anything in the revolvers that I work on.

BUT!

I have come to acknowledge that I need a better assortment of bit sizes and that this alone may reduce the number of times I have to replace screws because they look bad. Even screws carefully removed with the right size bit eventually get worn.

You read in an earlier post that I intended to invest a little mental effort in making a decision for myself about screwdrivers. In that same posts I cited two facts that drove me to pooh pooh Chapman sets. I said the radius of the tip grind was too small to provide parallelism between the side of the slot and the side of the tip. (The main reason for selecting hollow ground bits in the firstplace.) I also said that I can recall breaking some Chapman bits in heavy force situations.

But now I recall that the reason that I broke bits is because I did not have the right size bit. At one command, each of my techs had his own Chapman set and virtually every one of the sets was missing some bits, (primarily the most essential bits were missing). So yesterday I checked the Chapman set in my pistol becnh and, sure enough, the very bits I would need are missing. You see, my cat ("Buddy") is a little careless with his tools. So I am buying "Buddy" seven replacement bits for his Chapman set for Christmas. BOSESGUNS has them for between one and two bucks a piece.

napp
December 19, 2010, 10:32 AM
The length along the slot is a matter of leverage. The longer the bit the more leverage it can put on the screw head. A little bit shorter will not make that much difference, a lot shorter could raise a distortion in the screw slot.

Junkman understands my concern. I am comfortable with the bit not completely filling the slot end-to-end if it is close. I even consider this to be preferable when the screw is recessed.

This thread has turned into a screwdriver sizing thread; while my original question was, "Is it a characteristic of the Italian manufactured guns to cut thinner slots into the screw heads?" Apparently, the answer is yes.