# Deep Drilling Question



## jaychris (Feb 29, 2016)

I need drill a hole through some 3/4" nylon rod.  .5" diameter hole, 16" long.

I don't want to spend the money on a gun drill, but I can't think of other options.  This is the first time I've encountered the need to drill a hole this deep and I'm not sure the right way to go about it.


----------



## Randall Marx (Feb 29, 2016)

There was a thread on here a while ago about homemade drills for deep hole drilling. It discussed making a drill bit out of drill rod with one end ground in a particular way and it sounded like it is quite accurate. I'll see if I can find the thread and link it here for you.


----------



## jaychris (Feb 29, 2016)

Randall Marx said:


> There was a thread on here a while ago about homemade drills for deep hole drilling. It discussed making a drill bit out of drill rod with one end ground in a particular way and it sounded like it is quite accurate. I'll see if I can find the thread and link it here for you.


thanks!


----------



## Bob Korves (Feb 29, 2016)

What is the application and how accurate does it need to be?  Is tubing available that would fill your need?


----------



## jaychris (Feb 29, 2016)

Bob Korves said:


> What is the application and how accurate does it need to be?  Is tubing available that would fill your need?



I'm making a replacement part for a pepperoni stuffer - it doesn't need to be super accurate, but it does need to be food grade, which is why I am using a specific nylon rod.  The OD needs to be .75 and then I'll turn the majority down to .5" to create a flange.  The through hole doesn't need to be any particular diameter - the current (broken) part was 3/8", so I figured I would do the same.  

I have not been able to find any nylon tube that fit those dimensions.


----------



## FLguy (Feb 29, 2016)

jaychris said:


> I need drill a hole through some 3/4" nylon rod.  .5" diameter hole, 16" long.
> 
> I don't want to spend the money on a gun drill, but I can't think of other options.  This is the first time I've encountered the need to drill a hole this deep and I'm not sure the right way to go about it.


Electrictions Drills


----------



## FLguy (Feb 29, 2016)

FLguy said:


> Electrictions Drills


Sorry for  my bad reply, my network server crashed. A cheap way to do this is with an electrians drill bit. They come in various dia. and lengths.


----------



## TommyD (Feb 29, 2016)

How you holding this puppy?


Can you make a holder out if drill rod or the like and use wood spade drill.


----------



## FLguy (Feb 29, 2016)

Me again,I checked this website;woodshopbits.com and they have #WOO4185 1/2 dia. x18" long on sale for $18.09. Hope this helps.


----------



## Bob Korves (Feb 29, 2016)

Could you make either of these work?
http://www.mcmaster.com/#8628k35/=11c7k9p 
http://www.mcmaster.com/#8628k49/=11c7kt9


----------



## Randall Marx (Feb 29, 2016)

Sorry for the delay, but I finally found it. They are called D-bits and are made from a length of drill rod (length dependent upon need). Here is a link to one thread that goes into the idea. Part of the way down the thread, there is another link that discusses the making of the bits. Hope it helps!
http://www.hobby-machinist.com/threads/deep-hole-drilling.20208/


----------



## Terrywerm (Feb 29, 2016)

Instead of purchasing a gun drill, how about making your own??  The August 1965 issue of Popular Mechanics had an excellent article on the subject. You can read it at this link:  https://books.google.com/books?id=XOMDAAAAMBAJ&pg=PA166&dq=popular+mechanics+making+deep+hole+drills&hl=en&sa=X&ved=0ahUKEwjPg5eK2p3LAhUluoMKHdzWAhsQ6AEINTAA#v=onepage&q=popular mechanics making deep hole drills&f=false

Another method is to make a simple D-bit using a length of drill rod, either W-1 or O-1.

Cut a length of drill rod long enough to chuck up in your lathe or drill press and still drill the hole.
Square the ends with a file, grinder, or belt sander.  Remove any burrs from the end.
Use a centering head on a combination square and scribe a couple of lines at right angles to each other on one end of the rod.
Mill away almost one half the diameter for a distance of about 1" back from the end of the rod. Finish it with a file. If you cut away half or more of the diameter, the bit will cut undersize. You can probably get away with cutting up to within .010" or so of the center line.  Try to avoid any sharp corners in the base of the bit in order to prevent breakage.
Relieve the side of the cutter that does not do the cutting.
Back off behind the cutting edge to provide clearance.
Harden then temper to dark yellow, just on the cutting edge, not the whole drill.
Sharpen cutting edge on a stone




Granted, this may be a fair piece of work for a soft material like nylon, but if you need the hole to be true and straight it would be the way to go.

D-bits do have a couple of drawbacks, but they are minor compared to the gains.

They require a starting hole, typically about three times the diameter. This is easily done with a twist drill of the same size.
They must be retracted from the hole often to clear chips. You will spend more time retracting and inserting the bit than you will actually drilling the hole.
*ON EDIT:*  Randall found the old post where this was discussed at great length. I knew it was out there somewhere, but I could not find it. He posted it while I was writing this one up.


----------



## John Hasler (Feb 29, 2016)

I think that keeping the material straight is going to be a major problem.  Can you shrink or press it into a 3/4" tube?  I hope you have some material to experiment on.


----------



## Paul in OKC (Feb 29, 2016)

Aircraft length bits come in all sorts of sizes, and about 18" long. Use some here at the shop.


----------



## BGHansen (Feb 29, 2016)

My shop teacher in junior high brazed a rod to a jobbers drill bit and drilled a hole in a student's lamp base turning.  Could you braze a rod to the end of the drill bit?  My concern would be what do you do if the braze joint breaks.

Or maybe these from HF?

Bruce


----------



## jaychris (Feb 29, 2016)

Wow, thanks for all the tips guys!  Any number of these solutions will work, so I appreciate it.  I'll let you know what I go with - actually, I might order a bit that will work just for speed and try terrywerm's idea as well just for the heck of it


----------



## jaychris (Feb 29, 2016)

John Hasler said:


> I think that keeping the material straight is going to be a major problem.  Can you shrink or press it into a 3/4" tube?  I hope you have some material to experiment on.



I do - I have a bunch of it on hand, so if I f-it up, I can try, try again.


----------



## kd4gij (Feb 29, 2016)

But you can't drill it .500 and turn the od to .500


----------



## derf (Feb 29, 2016)

I tried to drill some nylon once for a bore guide about 8" long, and found no matter what I did it was like trying to drill spaghetti. The better choice is Delrin, it machines about 1000 times better than nylon.


----------



## 4GSR (Feb 29, 2016)

If you have a small lathe like a 9" South Bend, you could shove the material up in the spindle.  Let the spindle hold it reasonable steady while you drill the material.  Suggest drilling half way, turn it around and drill the rest of the way.  You'll probably have a mis-match in the middle. Just use the drill bit as a reamer and run it deeper to blend in the two bores.  That's how we used to do it on deep hole drilling machines, Trepanners we called them.


----------



## RJSakowski (Feb 29, 2016)

jaychris said:


> I need drill a hole through some 3/4" nylon rod.  .5" diameter hole, 16" long.
> 
> I don't want to spend the money on a gun drill, but I can't think of other options.  This is the first time I've encountered the need to drill a hole this deep and I'm not sure the right way to go about it.



I routinely make extra long drills  from a piece of rod and a jobber length drill bit.  I turn the shank of the drill bit down and bore a matching hole in the rod.  Early on, I used to braze them but I have found that Super glue works just as well.  I have never had one fail in use.  

Drilling a hole that deep in Nylon ( or Delrin) will most likely cause a problem for you though.  It would be virtually impossible to keep the hole straight over that length.

McMaster Carr sells an FDA compliant Nylon tubing, 3/4" O.D. x 1/4" I.D.  With the 1/4" pilot hole, you stand a much better chance of keeping the hole centered. http://www.mcmaster.com/#8628k35/=11cdvay


----------



## TOOLMASTER (Mar 1, 2016)

............


----------



## Jimsehr (Apr 3, 2016)

jaychris said:


> I need drill a hole through some 3/4" nylon rod.  .5" diameter hole, 16" long.
> 
> I don't want to spend the money on a gun drill, but I can't think of other options.  This is the first time I've encountered the need to drill a hole this deep and I'm not sure the right way to go about it.




Google Irwin speedbor bit 3/8 x 16 long   model 88706 $6.21,
jimsehr


----------

