tricky thread

Hi all,
I have an idea for a new invention but have a problem with machining a part,
Imagine a 40 mm dia X 50 bar with a 20 hole through, one end of the bar has
a 20 degree countersink forming a sharp edge to the OD. This csk blends with
the 20 bore by a 14 mm radius-looks like a trumpet mouth. Easy enough by
cnc - here's the catch, the 20 bore is threaded ( say 1.5 mm pitch ) and
this thread needs to follow the radius and the 10 degree face! the thread
form must be square to the bore ( obviously ) and the radius tangeant and
the angled face, the pitch over the changing diameter must also remain
constant-imagine being able to roll a similar pitch screw over the profile
so all the threads engage.
Is this possible to do ?, I know our cnc turners at work will shake their
heads, but not yet asked, It needs something like a cnc lathe with a tool
that progresively rotates as it moves over the profile. Is there a set-up
that is used for any similar job any where? The only thing I can think of at
the moment is one of those B&Q type door stops with a conical spring, which
doesn't really help.
All advice appreciated,
Cheers,
Mark G.
Reply to
Mark G
Loading thread data ...
This sounds like thread milling on a CNC. You can get thread mills that do have a carbide-insert that look the same as those used on the lathe. Problem is, you can't use the thread-milling algorithm (a helix-path) of the CNC.
But I may be way off, due to my lack of experience with CNC.
Nick
Reply to
Nick Mueller
Yes Me, Me ,ask me [ hands up jumping up and down with legs crossed ]
Are you ready for it.
You want that attachment that features in the recent thread
"Can anyone tell me what this set-up is for an a Myford I have just acquired ?" That will rotate the tool as it moves in.
Sorry couldn't resist but it's very close. Other than that I think what you want is not possible with a special attachment similar to this.
Even a CNC can't rotate a tool to keep tangential.
. -- Regards,
John Stevenson Nottingham, England.
Visit the new Model Engineering adverts page at:-
formatting link
Reply to
John Stevenson
Forget if it is possible
The question has to be asked. Precisely what would such a "thread" achieve?
Reply to
Mike
Can't disclose the purpose yet, be first to let you all know if it comes off ! Mark G.
Reply to
Mark G
what about tempering a wash-hand basin tap re-seating tool holder and using it as a tap?
Reply to
Billy H
Square to the bore, yes, but why must it be square to the radius tangent and the angled face?
Reply to
Peter Fairbrother
On further reflection, does it even have to be square to the bore?
Reply to
Peter Fairbrother
Sounds to me just a tapered thread.
Reply to
Billy H
Why not?
It sounds as if it is merely the addition of another axis (tool tilt?) the equivalent of rotating the tool holder under the computer' control.
What would be the problem?
I agree if you didn't have the axis set up, then it would be impossibl but I see machines with 17 axes of rotation advertised
-- rss ----------------------------------------------------------------------- rsss's Profile:
formatting link
this thread:
formatting link
Reply to
rsss
I think we need to keep practical here. I was talking about conventional CNC lathes which have fixed turrets. True fitting another axis will do this but who wants it. The user can't do it and won't pay to have it done and add 10K to the price of a machine for a feature that's not needed.
Once we get onto a machine with 5 or 6 axis that can do this the owner won't be interested in something like this due to cost. Programming this won't be cheap, probably more than the job is worth. -- Regards,
John Stevenson Nottingham, England.
Visit the new Model Engineering adverts page at:-
formatting link
Reply to
John Stevenson
tut tut get on with yer moderating over yonder LMAO...
Wayne...
Reply to
Wayne Weedon
Fame at last ;o) I am waiting for my sister to bring my camera back, to give you more pictures on that subject. I just hope you lads don't forget me by then. ;o) Ikie
Reply to
Ikie Cabolacov
Might be possible with a variation of a taper attachment or a tracer lathe, using a pattern to control the cross feed while threading.
Don Young
Reply to
Don Young

PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.