Jump to content

Tapping a hole


Gromit
 Share

Recommended Posts

I've to tap a hole for an EGT probe. The fitting is 1/8" NTP.

So I drill an 8.5 mm hole and tap it. I've been out playing with it on some bits of steel :D ; I've a few questions.

I've a starter and finisher tap.

I assume the starter is the one with a longer smooth taper on it.

What does the finisher do that the starter doesn't? :unsure:

What's the best lubricant to use while tapping? Paraffin?

As the tap is tapered, I'm a bit confused about how far into the hole I should run the tap(s).

Sorry for the basic questions, but this is all completely new to me

Link to comment
Share on other sites

the taper tap starts the thread more easily for u , then u go for the plug tap with squares the hole of do that u get a gd hold on it , u get a cutting compond for tapping but i use grease at work , when your tapping work the tap back and forth ie 1/2 forword 1/2 back then 1 turn forward so that u clear it out , just go slow and do ti right , no bother trying to rush it youll only break the tap ,

Link to comment
Share on other sites

... What does the finisher do that the starter doesn't? :unsure:

If you are threading through a piece of flat strap or similar, nothing. However, if you were cutting a 'blind' hole, i.e. not right through, you need the finisher to cut the thread properly right down the hole.

What's the best lubricant to use while tapping? Paraffin?

Trefolex, because it stays put, rather than dribbling away.

As the tap is tapered, I'm a bit confused about how far into the hole I should run the tap(s).

See answer above; right through if it's possible, or to just short of the base in a blind hole, then the same with the finisher - snapping a hardened steel tool in the hole is bad news ....

Link to comment
Share on other sites

Kiall's advice is good - a turn or so, then back off 1/2 a turn to break the swarf off before carrying on.

Good quality taps help, I'm guessing if you have a starter and finisher they're not from the 50p shop anyway.

I used grease last time I did any tapping as I was trying not to get swarf in my axle casing, seemed to work nicely.

Link to comment
Share on other sites

impervia grease i used at work , and to grease any bolts as its thick and water proof, although we have expensive taps they still do break as they dont like that much torque, although as mentioned above the finisher tap may still be tapered so if your going to tap a blind hole u may need a actuall plug tap which is square all the way to the bottom.

a good tool also to get it s a ratching dwang ie, link (no flaming , i make my living wiv them)

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...

Important Information

We use cookies to ensure you get the best experience. By using our website you agree to our Cookie Policy