Gunsmithing machinist handbook questions

[upjeeper]

does the Machinist Handbook cover the following?
RPM specific to drill bit size (e.g. how many RPM for a 1/2 inch hold in steel?)
does it give info as to when to use cutting fluid?
feeds / speeds for milling?

thank you.

 

[WhiskeyBravo]

I don't have the latest version (it's about v29 or so)... But I am sure the much later versions contain lots of reference info relative to the 'modern environment' (complex cutter forms, coatings, material specific kinds of stuff that started with the common advent of carbide tools in the 70's, along with all manner of CNC programming references)...

However, if you're using an older bible (mine are v10 (circa 1930's) and v21) you will find plenty of reference material to answer the questions you're trying to ask especially as regards manual tools and HSS cutters.
Lastly, there are only a few materials that won't cut better with lubrication... The real question is which lubricant for which material!

That all said, a great subscription service that can answer virtually any question acceptably considering tool, tooling and target material, can be found at GWizard: A CNC Machinist's Calculator for Feeds and Speeds.
Don't be off put by the 'cnc' part!

 

[Luvman]

As a general rule yes it does.

Another general rule assuming the drill is made of HSS is to run it 80SFM (surface feet per minute) speed if you're drilling 1018 CRS. If drilling pre hardened 4140, a common steel found in firearms, run it at around 40-50SFM.

To calculate SFM into RPM use this formula: cutting speed(SFM) x 3.82/cutter diameter(inches)

1/2" drill in CRS should be running 611RPM. In 4140 about 344RPM (45SFM)

Hth,
LM

 

[scottyr44]

I have the newest version... but have never used it for speeds and feeds there are many variables. My time as a machinist I used feel, sound and finish to judge feeds and speeds

Sent from my SCH-I605 using Tapatalk

 

[LRI]

Research the tooling manufacturer. The better one publish recommended speed and feed setting specific to a particular type of drill.

Then use this:

http://www.custompartnet.com/calculator/drilling-speed-and-feed



Milling Speed and Feed Calculator

 

[Equus]

I have the newest version... but have never used it for speeds and feeds there are many variables. My time as a machinist I used feel, sound and finish to judge feeds and speeds

Sent from my SCH-I605 using Tapatalk

THIS. My newest version is 27 and this information is in there. These numbers are good for reference, as feel, sound and finish are what matters.

 

[scottyr44]

I always say they will get you close. But really it's up to you as the machinist to make a product that you feel is good so if you can fiddle with numbers to make a rounder hole or a smoother surface go for it

Sent from my SCH-I605 using Tapatalk