What to use for cutting oil to tap heavy gauge steel


  #1  
Old 05-22-24, 03:17 PM
C
Member
Thread Starter
Join Date: Jun 2005
Location: Goodwood, Ontario
Posts: 149
Received 0 Upvotes on 0 Posts
What to use for cutting oil to tap heavy gauge steel

It's normally easy to change the knife on my old Mighty Mac chipper. Remove 3 screws, position the sharpened blade and put the screws back in with Loc-Tite. Today the screws came out easily but I couldn't put in new or old ones. I cleaned the threaded holes with compressed air, PB Blaster and a paper towel wrapped around a Q-tip. That helped on two holes, but not the third. I've never done a tap, but videos suggest it's doable with a manual tap. A local big box store (Canadian Tire) has a basic tap set on sale, but no stores here sell cutting oil. I read that WD-40 and 3-in-1 oil are OK for aluminum but this is old fashioned heavy gauge steel. Is there a readily available substitute? Thanks

5/16-18 flathead socket screws thread in with Loc-Tite. There is no nut behind.
 
  #2  
Old 05-22-24, 03:45 PM
P
Group Moderator
Join Date: Mar 2003
Location: NC, USA
Posts: 28,164
Received 2,271 Upvotes on 2,023 Posts
If you are simply cleaning up existing threads you can use almost anything like; motor oil, 3 in 1 oil, gear oil... If you want a product specifically for tapping holes in steel I like Rapid Tap.
 
  #3  
Old 05-22-24, 03:48 PM
XSleeper's Avatar
Group Moderator
Join Date: Dec 2004
Posts: 27,251
Received 1,960 Upvotes on 1,757 Posts
Any kind of oil works. No matter what you use you still need to drill the correct sized hole for your tap (use oil as you drill) and you still need to run the tap in and out, in and out as you cut your new threads.
 
  #4  
Old 05-23-24, 04:01 AM
B
Member
Join Date: Oct 2015
Location: Ct.,USA
Posts: 3,339
Received 314 Upvotes on 277 Posts
I an assuming you are not changing thread size. You don't need to redrill a tap hole. It already exists and you have removed/replaced same screws many times. You only need to chase the existing threads with a standard tap to remove the Loc-Tite and any distress from last removal.
 
CanadianGuy voted this post useful.
  #5  
Old 05-23-24, 06:35 AM
C
Member
Thread Starter
Join Date: Jun 2005
Location: Goodwood, Ontario
Posts: 149
Received 0 Upvotes on 0 Posts
I don't want to change the thread size, as beelzebob noted. Just clean/fix the troublesome threads. The screws have indeed gone in and out many times over the years. I thought I had inserted a photo but that didn't seem to work.

I have found a local source for cutting oil -- an auto parts shop. It didn't occur to me to check there because I don't work on cars.

Thanks to all.



 
  #6  
Old 05-23-24, 08:21 AM
P
Group Moderator
Join Date: Mar 2003
Location: NC, USA
Posts: 28,164
Received 2,271 Upvotes on 2,023 Posts
But, since you are only chasing or cleaning up existing threads the specific type of cutting oil isn't important. Any oil will do. I'll even clean up threads dry, but using oil makes it easier and is better for the life of the tool.
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description: