Need help finding 6-42 tap

[MK20]

This is the correct tap for an old marlin magazine tube and is apparently hell to find. Does anyone know where to find one or who would build one for me?
Thanks.

 

[sirhrmechanic]

Mscdirect.com

Manhattan supply co.

It’s an standard US tap. I’d suggest ordering both a starting tap and a bottoming tap if you are doing a bling hole.

Sirhr

 

[packratt]

McMaster carr

 

[sirhrmechanic]

^^^ or them.

Sirhr

 

[MK20]

Thanks. My good friend is the end user of this tap. He is the sole source for marlin rifle screws in the US. He has had a hard time finding one. This should straighten it out for him.

 

[MK20]

Ok, so neither supplier mentioned has a 6-42. They have 6-32 and 6-40, but not the needed size. It is quite the oddball. Any suggestions on where to find this specialty tap?

Edit, after much searching, it looks to have to be made. Who could do something like this?

 

[Warpspeed]

6-42 ? are you certain ?

6-40 is standard ; 6-42 isn't on any chart I have.

 

[Warpspeed]

Ok, so neither supplier mentioned has a 6-42. They have 6-32 and 6-40, but not the needed size. It is quite the oddball. Any suggestions on where to find this specialty tap?

Edit, after much searching, it looks to have to be made. Who could do something like this?

https://www.regalcuttingtools.com/special-taps

 

[Im2bent]

You sure it's not 6-40? I can't find a a 6-42 tap on the tap charts.

 

[Im2bent]

Hmm a day late and a dollar short story of my life

 

[LeftyJason]

Did a search for 6-42 pitch diameter and came up with nothing. Searched for any screw that is 42 tpi and all I find is thread tpi checkers. Only place I saw a 42 tpi anything is a 10-42 on some place I've never heard and aren't sure if it's real or not.

You sure it's not a m3.5x.6? Very close.

Thread / Dia in. /Dia mm/ thread count tpi/ thread count mm/ tap drill

M3.5x0.6	0.1378	3.5000	~43	0.600	2.9 mm
#6-32	0.1380	3.5052	32	0.794	#36
#6-40	0.1380	3.5052	40	0.635	#3

 

[MK20]

Nope. It's 6-42 thread for a 120 year old marlin lever gun.

 

[roostercogburn98]

Try jackfirstinc.com. Old gun stuff and maybe they have a direction

 

[Trigger Monkey]

I could be talking out of my ass but what about a metric tap? Dimensions on a 6-42 tap would be about .137 X .023 and a 3.5 X .60 would be about the same.

Haha just saw the post above by LeftyJason.....sorrrry but it could be a potential solution, good luck.

 

[Makinchips208]

I can grind you one but it would probably not be cost effective.
I would do like others said and use the metric tap.

 

[LeftyJason]

Nope. It's 6-42 thread for a 120 year old marlin lever gun.

I would seriously get your friend to try a m3.5x.6 screw.
Doing the math. 1÷42=0.0238095238
.6mm to imperial=0.023622
That is 0.0001875238" different between the tpi.

How much thread engagement? If short enough you might not even be able to tell the difference.

Doesn't hurt to try.

Does he have access to a pitch mic? metric thread converted to imperial.
Major Dia 0.1369-0.132
Pitch 0.1216- 0.1182
Minor 0.1113-0.105

 

[Im2bent]

You commies are seriously suggesting a METRIC tap in an American gun?!?!?!?!?!
What next? dogs and cats living together?

 

[Trigger Monkey]

You commies are seriously suggesting a METRIC tap in an American gun?!?!?!?!?!

 

[Makinchips208]

You commies are seriously suggesting a METRIC tap in an American gun?!?!?!?!?!
What next? dogs and cats living together?

It’s technically not metric,
it is 0.1378”x42.33

 

[n2ishun]

6-32
6-40
6-48
That's it, if it's REALLY 6-42 you'll have to have a tap made.....and that shit ain't cheap, figure prolly $150-200'ish.

 

[pitspitr]

You commies are seriously suggesting a METRIC tap in an American gun?!?!?!?!?!
What next? dogs and cats living together?

Ever heard of a US Springfield 1795-1892?

 

[B'N'F]

Could it by chance be an old BA thread? I've run into this on older stuff made in North America, but ended up finding out it was a BA thread that got used.