doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Parker frame size ??

It MUST be one or the other.... Parker Bros never made a 2 3/4 frame.

"" sn is 192706, straight stock and 28 inch tubes.""

Who has "The Book" and what does it say?

The Serialization Book won't give the frame size.

Bill, it is very hard to measure hole centers with a Vernier caliper. Such a device is used to measure objects with square ends. You are better to measure hole centers in breech faces with a machinist's scale. You don't have to identify the center of the holes, just identify the edges of the holes, a much more accurate measurement.

I have no problems at all measuring firing pin hole centers using a set of calipers. Matters not if they are Vernier, Dial or Digital except as to how they are read. Vernier's are the hardest to read but have the advantage of having nothing what-so-ever to get out of adjustment. I still have 2 or 3 vernier calipers from my machinist days which I use rather frequently. Also have a 6" Starrett Dial caliper which I use a lot for the ease of reading with my Old Eyes.

The calipers all read to .001" while the smallest graduation I recall ever seeing on a machinist scale was .010" so a bit of interpolation is need if you want it closer than that. If the scale is all in fractions, which many are, then the smallest increment is normally 1/64" (.0164"). I can Certainly read it closer than that with calipers.

eightbore, as a former engineering supervisor at Chrysler's Trenton Engine Plant (2.5 million sq. ft. machine shop) I agree with you. Also my method was a bit casual. By carefully checking from the outside of one hole to the inside of the other and then reverseing directions I get an average of 1.128. I believe this a good solid number and seems to indicate #2 frame. We had a tolerance of 3 light bands on water pump seals, try to measure that!
bill

Without seeing just how "Casual" your first method of measuring was I will not comment on that.

I will say though having used measuring tools, including micrometers, calipers, scales etc on a daily basis for 35+ years an error of .042" (1.170"-1.128") was not a direct result of choosing dial calipers for the measurement.

While we are Bragging, Closest parts I ever had to build had a tolerance of +.00005 -.00000. They were measured on a Browne & Sharpe Super Mic which one looked into a window & watched for a light beam to bend to get consistent pressure on the anvil. Thimble was at least 6" in diameter so even the .0001" (1 ten thousandths inch) marks were around .075" apart.
I have also lapped parts where we had a tolerance of "1" light band. Is that a match??

.042" is near 3/64", I could measure a firing pin hole's spacing closer than that with a Harbour Freight Tape measure.

PS; I'm through patting myself on the back for now, pass the linement Please.

Guys, it's not that complicated - we're talking sixteenths of an inch. No, it's not going to be precise but it will be closer to one sixteenth or the next...

Eightbore pretty much nailed as for ease of measuring - that being from the edge of one hole to the corresponding edge of the other hole... pretty simple really.

One thing I try not to do measuring is convert. While I like to work in decimal inches with a micrometer/dial/digital caliper, I have metric mikes and dial/digitals as well as fraction veneer calipers.

Looking for Parker pin spacing in 16ths machinist rule calibrated in fractions gives me fast accurate readings.

Boats.

Are you sure about that, Dean?