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Drilling a straight hole

Mechanola

Stainless
Joined
Mar 21, 2011
Location
Äsch
Where are you located about? Juneau? If you can find someone with a broacher or have one yourself, it will help you get them straight and to size. Else you can use a drill bushing to hold the tool in place. Yet another measure is to drill from both sides and go through after that with a three-flute drill, slowly. Reaming is just for size, not to straighten anything.
 

Thunderjet

Hot Rolled
Joined
Jun 24, 2019
Spot, drill thru .195 with carbide, then jig bore cutter to size, all from one end and one settup.
 

scott-ak

Plastic
Joined
Oct 12, 2021
lots of good ideas. I'm kinda slow on some problem solving stuff and turning handles is my retirement gig.

Someone commented about materials and drilling from the other side. That go me thinking... I thot it was odd that all the holes deviate toward the center when they should be random or maybe all drift to the right or left or up or down.

In addition to the problems of drilling a hole many times deeper than the diameter, maybe the deviation is getting worst as the supporting material get thinner on the threaded end? I wonder if I might hold the line better in an unthreaded part?

I am patiently waiting for the guhring bit to arrive...
 

EPAIII

Diamond
Joined
Nov 23, 2003
Location
Beaumont, TX, USA
Oh, I was not recommending them as an A-#1 supplier. Just to show that the longer end mills ARE AVAILABLE. Frankly, I can't recall ever ordering anything from them.

If they have them, I am sure other suppliers do as well.



I am sure mscdirect is a fine company but they are jerks about shipping. They charge 45$ for shipping the first end mill on that page
 

scott-ak

Plastic
Joined
Oct 12, 2021
The guhring bit made a huge difference and made very nice holes. I measure less than 5 tho runout. Couldn't ask for better from a 30 yo machine. Used the same pilot method with a 4-flute end mill then peck drilled the rest of the way. Maybe one difference was wiping the swarf off the bit with every peck. Holes are .204 x 1.990
 

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michiganbuck

Diamond
Joined
Jun 28, 2012
Location
Mt Clemens, Michigan 48035
Showing the part in post #1 with a stubby little V block makes me wonder how you are holding it and what type of machine you are using.

A mill or drill press should have a part holding device that is checked for tram.. and stout enough that it will not deflect to cutting-tool pressure.

QT: [The guhring bit made a huge difference and made very nice holes. I measure less than 5 tho runout.]

What was running out, the end mill cutter, the drill?, as it was being held in a chuck or something?

What are the larger surface-finish circle marks at photo 1 in post #30?
 

scott-ak

Plastic
Joined
Oct 12, 2021
Showing the part in post #1 with a stubby little V block makes me wonder how you are holding it and what type of machine you are using.

A mill or drill press should have a part holding device that is checked for tram.. and stout enough that it will not deflect to cutting-tool pressure.

QT: [The guhring bit made a huge difference and made very nice holes. I measure less than 5 tho runout.]

What was running out, the end mill cutter, the drill?, as it was being held in a chuck or something?

What are the larger surface-finish circle marks at photo 1 in post #30?

the part is being held vertical and I switched to a large v-block for a better hold
It's a bridgeport clone 9x54
the machine is trammed and the part checked for being held vertical.
the marks :( the bit is too short for the job and is held in a drill chuck. The bit only reaches about 3/4 of the way when chucked up. After drilling to that depth I let a little out, twice, and drilled the rest. The marks are from swarf between the chuck and the work.

Maybe runout is not the best description of the hole. Deviation might be a better word. In every case, including several practice attempts after scrapping the first part, the holes deviate toward the center of the work and I can't make sense of that.

The machine is 30 years old and IMO it was shear luck getting any hole with this diameter to depth drilled straight
 

scott-ak

Plastic
Joined
Oct 12, 2021
I guess everyone but me knows what a barrel nut is ,what its made from and how long it is.Also ,what is a gas tube? Edwin Dirnbeck
A barrel nut holds a rifle barrel to the upper receiver. In this case a semi-auto in .308. The gas tube is the little stainless tube above the barrel. When the bullet passes the hole in the barrel a small amount of gas pressure is sent down the tube forcing the bolt back extracting and ejecting the spent shell casing.

This barrel nut is made from aluminum. Some are steel.
 

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