What's the most appropriate type of tap to make this M9x0.75 thread?

[Clive603]

Got a basic drawing and preliminary enquiry about making "some" adapter devices to screw onto 9 mm diameter spindles threaded 0.75 mm pitch, metric fine.

Device itself is trivial to make. Something to do with watchmaking or watch repair I understand. However I'm somewhat at a loss as to what type of tap to purchase to cut the thread with.

"Some" translates as between 2 and 50, material can be brass or stainless steel with a "really nice" finish. Doncha love it when customers go all precise on you!

I imagine the thread needs to be a bit better than what will do for common fasteners so as to minimise wear on the spindle. Adapters will frequently be removed and refitted.

Obviously the tap has to be good quality but what style. Serial taps allegedly produce a nicer finished thread but are they really any better than a quality brand of spiral point machine tap. Or is there something I don't know about specially intended for this sort of job.

Plan A is to drive the tap with one of my Pollard tapping heads.

Clive

 

[Benta]

From a thread quality point of view, I wouldn't expect much difference. But machine taps normally cut deeper than a serial tap set (2 taps for metric fine). Depends on your drawing.

 

[Limy Sami]

Clive, I suspect that with that dia and pitch you will (almost?) have to take whatever taps you can get.

I stand corrected, ...bigger choice than I thought, Rotagrip are my go to for oddball threads

IME These Volkel ''ain't at all bad'' Rotagrip - M9 x 0.75 HSS Tap Set Volkel

These are a bit cheaper Rotagrip - M9 x 0.75 HSS Tap Set

 

[Clive603]

Limy

Yup I figured that choice in that size was "take what you can get" but when you start looking around there is a decent range out there. Especially as I didn't hear customer whimper when I said probably about £50 for the taps! A Customer with some understanding of real world costs! How unnatural can you get. Good start to the year. May there be many more like that. Napkin type drawing and I had to figure the threads out from a "one like this but different" sample but 'spose you can't have everything. This is where he keeps me hanging for a month and decides not to bother...

What got me wondering about serial taps was this E-Bay listing No 310426478825. Especially as they are claimed to be good for stainless steel.

Benta confirms my impression that serial taps cut a bit shallower than normal machine taps so maybe that's the way to go. My Pollard tapping heads seem to do fine with ordinary straight flute taps given a sympathetic touch on the feed handle.

Not gonna cheap out on taps. Always more trouble than its worth.

Clive

 

[Clive603]

Updating.

I went with the serial taps via that E-Bay listing. I'm impressed. Worked a treat producing a very nice thread and far easier in stainless than standard taps .

Looks like serial taps will be the best fit for my sort and quantities of work so that won't be the last set I buy.

Customer loved the sample but still waiting for the main order. Situation normal then. Reminds me why I try to stick with emergency, one offs and similar where I can take the money with one hand and hand the job over with the other.

Clive

 

[Limy Sami]

where I can take the money with one hand and hand the job over with the other.

Clive

Money? .................as in getting paid for working? …………..is this something new?

 

[Conrad Hoffman]

Is this adapter going on a machine spindle of some sort? If so, I'd single point it, or make an arbor and finish the part after tapping it. It probably needs to run concentric. I don't think the type of tap is going to make a lot of difference. Choose it as you would for any other job. The tap drill hole might be finish reamed for best thread quality.

 

[Clive603]

Is this adapter going on a machine spindle of some sort?

Ha. Thats what I was led to believe. However when the man came to pick up the sample I asked him directly what it was for. Turned out that it was merely a simple knurled stop ring for a watchmakers pressing thingy. He did a quick Google search on my computer, bought up a picture of something that looked worth about a tenner and said "These are the good Swiss made ones. They cost nearly £1,000. There is a cheaper Chinese one for about £200. But they are pretty crap."

I nearly fell off the floor.

Turns out proper Swiss made version of the bit I made is £50 + VAT + delivery. But they don't make the size he wanted. No wonder he was happy to offer me £20 a pop for 22 mm of 5/8 stainless knurled on the outside, drilled and tapped with two 4 mm lock screws coming in from the side.

Clive

 

[gsg9.ca]

" Turned out that it was merely a simple knurled stop ring for a watchmakers pressing thingy "

Phew, glad that worked out for you.

Just as a warning/caution if someone asks for oddball threads do a quick google check and see what they're most often used for. 9 x 0.75 is not uncommon in firearms. Thus your trivial watchmakers gizmo can inadvertently become a suppressor adapter in very short order.

 

[Mechanola]

Swiss mechanics tend to avoid M 9. I once asked the tool handler with a 80-people shop for an M 7 LH tap which made him go berserk. ONLY EVEN NUMBERS! I personally have no problems with odd sizes.

But be it the series III M 9 thread, buy a tap, give it grease, break chips often, clean them out, and sell a rarity at $$$.