Tapping 10-24 in blind hole SS 304

[Nogoingback]

I am using olive oil , is there a non-toxic tapping lube or paste?
Thanks
C

Tap Magic Eco-Oil - Tap Magic

Tap Magic Eco-Oil

www.tapmagic.com

This might be better. Haven't tried it yet, but planning on it.

 

[Cr23484]

smells great, but I'd be worried about flys, mice and rats.....
-brino

Thanks, gonna try Tapmagic Pro Tap

 

[mmcmdl]

Exotap . Bring the chips out .

 

[ezduzit]

Thanks, will try a #19, and try to tap with oil( all I have at this point)
C

10-24 calls for a #25 drill (0.1495"). Your #20 drill (0.1610") is already unnecessarily oversize at 0.0115" over, so there is no need to go even larger!

Check your tap. It may be a re-threading tap. Don't start the hole with a bottoming tap. And watch out that you aren't work hardening the material when drilling and countersinking.

Use tapping fluid or even dark pipe threading oil.

 

[mikey]

Might check your chart again. #25 drill is for aluminum and other soft materials.

 

[Briney Eye]

Hi everyone,
Need some guidance with SS 304 hex head bolt that I drilled 1.25” with a #20 hss 135 point drill.
Tap worked fine in a steel bolt, but can’t get it started in the SS, even with a chamfer?
Brand new tap, HSS
ANY ADVICE IS MUCH APPRECIATED
C

304 is a challenge to tap. It work-hardens badly and does everything it can to make life miserable.

To begin with, did you use a good, free-cutting drill to begin with (preferably carbide)? If you had any difficulty drilling the hole then you've already caused some work-hardening that will make tapping more difficult.

Start with a high-quality tap, not something from the hardware store. A lot of people will suggest power tapping with a spiral flute tap. Working a low-quality tap in and out will harden the 304, eventually seize, and break the tap. Then you're looking at burning the tap out or starting over.

 

[brino]

I like this thread chart.
https://littlemachineshop.com/reference/tapdrill.php

It's easy to find the drill for either 50% or 75% threads, depending on material, application, etc.

for #10-24 it shows:


-brino

 

[pstemari]

Castrol Molly-D and a decent HSS tap.

Not olive oil, not a carbon steel big box store tap.

 

[bhigdog]

Best tapping lube is bacon grease. .................Bob

 

[Cr23484]

I like this thread chart.
https://littlemachineshop.com/reference/tapdrill.php

It's easy to find the drill for either 50% or 75% threads, depending on material, application, , etc.

for #10-24 it shows:
View attachment 288484

-brino

Thanks , that is the exact chart I am using.
C