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Cutting Threads

Cutting Threads

Postby swooshdave » Fri Apr 18, 2014 9:55 pm

Image

Image

I need to cut some threads in the piece on the left. The thread size is M22 x 1.5, and the hole looks to be the correct size for threading.

What would be better, to buy a hand tap or pay someone to cut the threads with a lathe?
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Re: Cutting Threads

Postby nickguzzi » Fri Apr 18, 2014 10:09 pm

Fixturing that may be a pain. Depends on what tooling you have against how much the guy with the lathe needs the work.

My immediate thought was why not just weld the sucker in there? Or just remake the thing new in one piece?

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Re: Cutting Threads

Postby swooshdave » Fri Apr 18, 2014 10:52 pm

Time and expense.
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Re: Cutting Threads

Postby ashman » Fri Apr 18, 2014 11:01 pm

Buy the tap and do it yourself, just make sure when you tread it in the tap is straight and the hole is drilled for the right size tap and you shouldn't have any problems, just take it slow and easy.

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Re: Cutting Threads

Postby wakeup » Sat Apr 19, 2014 2:30 am

If it was me I would screwcut it on a lathe, I think you 'Merkins call it single pointing. Simply because ....
1/ You can "creep up" on the correct, snug, thread size
2/ It will be square, so the O seal will do its job
3/ Just check the cost of an M22 x 1.5 tap.
Alternatively, as nickguzzi said, make a solid new one.
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Re: Cutting Threads

Postby olChris » Sat Apr 19, 2014 3:48 am

So you are talking metric !!!...... go down the local supplier and get one reducer from the biggin to what you need.... Throw away the intermediate reducer and just have one!!!!
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Re: Cutting Threads

Postby swooshdave » Sat Apr 19, 2014 7:30 am

I need either a M30 to M22 or M30 to M16 reducer but I've not been able to find one. Yet. But you are correct, that would've the easy route.
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Re: Cutting Threads

Postby texasSlick » Sat Apr 19, 2014 6:15 pm

The main problem with hand tapping is to go in straight...a difficulty that seems to increase in proportion to the tap size.

My trick is to chuck the tap in a drill press, remove the drive belt, then square the part in my drill press vise. Then turn the spindle or chuck by hand while applying downward pressure with the spindle feed, just until I get 2 or 3 shallow threads started. Then I can use the tap handle and finish threading by hand.

You cannot chuck up a M22 tap in a 1/2 inch drill press, but you could do the same trick with a small lathe ( if you have a lathe and do not know how to cut a thread).

Not having a lathe, you will have to fabricate a jig or fixture to hold a M22 tap true to the bore of the part you are trying to thread.

Good luck

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Re: Cutting Threads

Postby worntorn » Sat Apr 19, 2014 7:04 pm

If done on a lathe you need to find a lathe with metric gears.

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Re: Cutting Threads

Postby swooshdave » Sat Apr 19, 2014 10:00 pm

If you have a lathe to chuck the tap into you also need something in the tailstock.
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Re: Cutting Threads

Postby nickguzzi » Sun Apr 20, 2014 1:46 am

Plus from the picture, it looks like one of those cast malleable iron plumbing/steam fittings so can't be taken as square or parallel.
Doesn't look like there is much to chuck it by, so you start by making a mandrel or split collar ... oh yeah, you don't have a lathe. Its a nice little job if you are just playing and paying yourself. Someone else "on the clock" will cost proportionally more.
A new decent tap @around $20, and you still have the problem of how to fixture it.
Perhaps you could get a thread compatible "tee" which you could use in a machine vice? Especially if you could mill the sides flat so it would be standing properly vertical. Then as mentioned use your drill press for preference, but if you hold it securely, you may find a hand job is acceptable.
You don't say what it is for, maybe neerenuffisgudenuff?

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Re: Cutting Threads

Postby GRM 450 » Sun Apr 20, 2014 2:23 pm

Cagiva / Pantah cable gland nut?

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Re: Cutting Threads

Postby swooshdave » Sun Apr 20, 2014 2:29 pm

GRM 450 wrote:Cagiva / Pantah cable gland nut?


Close. 860GT w Sasches Ignition.
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Re: Cutting Threads

Postby GRM 450 » Mon Apr 21, 2014 1:01 am

Sasche work well on 860s

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Re: Cutting Threads

Postby swooshdave » Mon Apr 21, 2014 11:48 am

GRM 450 wrote:Sasche work well on 860s


If you have the right adapter! :wink:
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