[4]

Drilling across a threaded shaft's diameter and/or threaded adapter's diameter

[3]
[10] Like what you see?
Click here to donate to this forum and upgrade your account!

Scott(GA)

Active Member
Registered
Joined
May 26, 2014
Messages
31
In the JET Lathes, Mills, Saws, Etc. Forum I posted my efforts at adding a Z-Axis Powerfeed to my JET Milling Machine.

Pretty much the last step of the installation is to drill a 5mm hole through the Powerfeed shaft & Manual Crank Handle adapter and insert a Spring Pin.

I had thought I'd take the adapter off the shaft and drill the hole through it using the Milling Machine but I was concerned that doing so - without something inside the adapter to protect the threads - might cause problems.

The issue is explained in detail in the Powerfeed thread: Here's a link to the actual POST that details things with pictures and such.

As I was having issues finding a bolt that matched the internal threads of the Adapter, I was wondering if drilling through the Adapter without something in the hole would be a mistake.

Scott
 

Dave Paine

Brass
Registered
Joined
May 10, 2014
Messages
813
I think the issue is burrs on the inside when the drill exits the top side of the hole. May also get burrs on the bottom side. If I were doing this I would prefer to have a tap to clean up the burrs. If you make a 7/8in x 12 tpi plug and screw this in, you may still get burrs and may have a challenge getting the plug out.

7/8in x 12 tpi is a special thread. Taps exist, just are not cheap.

7/8in x 12 tpi tap at Victor Machinery.
 

markba633csi

H-M Supporter - Gold Member
H-M Supporter - Gold Member ($25)
Joined
Apr 30, 2015
Messages
3,166
Making a "pseudo-tap" would be a good way to avoid the burr problem- make a threaded shaft and mill a couple slots lengthwise on it, like a tap. Then use it to chase the threads in the adapter after you drill. You may not even need it if you use a nice sharp drill, a dull drill will leave a nasty burr for sure
Mark
 

P. Waller

H-M Supporter - Sustaining Member
H-M Platinum Supporter ($50)
Joined
Mar 10, 2018
Messages
901
There are methods of creating such holes without burrs but few hobby shops would have the equipment for it.
 
[6]
[5] [7]
Top