Deep hole drilling question

[jeff]

I have a 15xD Guhring 1/4" drill that I need to drill approx 5" deep. This hole will pass through the side of another existing 2" bore, BUT I made plugs that will go into that 2" bore so that the 1/4" drill won't drift.

Does anyone forsee any issue with how I'm doing this?

 

[specv]

I have done this before and it works great, as long as you have a new plug each time. make sure that you don't have too much clearance or you will get a burr on the plug and may have a hard time getting it out

[jeff]

Thanks!

I plan to rotate the plug for each part. I have about a .002" clearance from the plug to the part.

[Guyinthedesert]

Thanks!

I plan to rotate the plug for each part. I have about a .002" clearance from the plug to the part.

If you rotate the plug, the next hole will be passing through the center of the previous hole at an angle. Could be a problem.  We've done this a couple ways. 1.You could drill the 1/4 through the first wall, then switch to a 1/4 dia  long center drill and spot the hole on the other side of the bore. 2. Drill the 1/4 hole first. 3. Install a removable detail in the fixture with a 1/4 drill bushing in it.

[jeff]

If you rotate the plug, the next hole will be passing through the center of the previous hole at an angle. Could be a problem.  We've done this a couple ways. 1.You could drill the 1/4 through the first wall, then switch to a 1/4 dia  long center drill and spot the hole on the other side of the bore. 2. Drill the 1/4 hole first. 3. Install a removable detail in the fixture with a 1/4 drill bushing in it.

The location of the 1/4" hole is off center of the plug, and that allows me to use the plug 3 times with no existing hole. 

[Teh Bear without Brains kinda idiot]

I would drill 3-5 mm deep hole on the previous hole with the long 1\4 end mill instead of center drill .

As a matter of fact I did it all the time when I was doing this kind of work

 

 

HTH

[Justin Beebe at Folsom Tool]

You might want to try starting the hole with a 1/4 inch stub drill 1.00 deep into the plug then drill the hole to final depth with the long 1/4 inch drill.  Ghuring series 5514 drills hold size and location very well and I have used them to start deep holes before then I finished the holes with a longer drill.  It worked out great for me.  The only difference is I wasn't drilling through a bore with a plug in it.  I think this method would work  well for your application as well.

[jeff]

It's working good so far, I'm using a 140deg stub drill to pilot 1xD and then using the deep hole drill.

It's my first time drilling anything this deep without peck so needless to say I was a little tense when I hit cycle start on the first hole lol.

[shazam/TPP]

glad it's working good, here's another thought. drill a .25 hole about .75 deep then switch to a gundrill with thru spindle coolant, the initial .25 hole acts as a drill bushing, feed the gundrill in approx .5-.625 then turn spindle and coolant on.

[jeff]

glad it's working good, here's another thought. drill a .25 hole about .75 deep then switch to a gundrill with thru spindle coolant, the initial .25 hole acts as a drill bushing, feed the gundrill in approx .5-.625 then turn spindle and coolant on.

That's basically what I'm doing.  But not a gun drill, I'm using a Guhring deep hole drill 20xD. With a pilot drill going .250 deep. entering slow and then turning on coolant and ramping up to speed and then drilling.

It's giving me a chubby.

[jeff]

Here's an update on how it's going.  

http://youtu.be/X3HPM1OhQic

[Guyinthedesert]

What is the material? 'm assuming it';s not inconel

[jeff]

4140 annealed