Senior Member
i wonder if someone could help me with some pushrods i am making . i have some threaded rods from great planes . the tread is 4-40 and it is about an inch from the end. how do i cut new threads at the other end?i am thinking of buing a 4-40 tool but , do you think that the diameter of the rod will let me cut the threads? i noticed that the rod i slightly smaller i diameter outside the threads area. i know that these cuting tools require i larger rod , so to cut the thread. i assume that the original threads made by presure and not by cutting. thats why they use smaller diameter rod. but will i be able to cut new at the other side or to abandom the idea ?
Hello
Abandon the idea Go for something like this 4-40 Adaptors and solder them on the end
Here is the link for you to look at
http://www.sussex-model-centre.co.uk...xd.asp?id=1553
Styk
Abandon the idea Go for something like this 4-40 Adaptors and solder them on the end
Here is the link for you to look at
http://www.sussex-model-centre.co.uk...xd.asp?id=1553
Styk
Senior Member
hi Styk,
i have already them and i would like to avoid them becaause of weight issues.
at tlast i will use them...
thanks
achilles
i have already them and i would like to avoid them becaause of weight issues.
at tlast i will use them...
thanks
achilles
Senior Member
Styk's idea is probably the best since the threads on the rods that you have are created by a rolling process not a cutting one. In a thread rolling process, the piece being threaded (the pushrod in this case) is rolled between two dies to create the thread. For mass production, it is a faster method of creating the parts. It also creates a stonger thread, however, for our uses that isn't really a consideration, ie, for what we are asking the pushrod to do, either type of thread is more than strong enough.
I've cut threads in 2-56 and 4-40 rod, using the appropriate die. The threads aren't quite as deep as the rolled threads, but hold just fine. Just clamp the rod in a vise or hold it with vise-grips, and take your time, The rod will try to twist as the die turns, just advance a short way, then back up, advance some more, repeat until you have the length of threads you want.
Senior Member
hi khodges,
i am planing to use the dubro ball links with the 4-40 threaded rod. althought that the threads woill not be very deep, do you hink that it will holds? also any suggestion about die brand?
i see many dies from carbon steel , titanium, ... and i am a bit confused.
there are sets of taps and dies to ebay from 10-50 $ . do you or anyone else have any experience with that kind of tooling?
thanks very much
achilles
i am planing to use the dubro ball links with the 4-40 threaded rod. althought that the threads woill not be very deep, do you hink that it will holds? also any suggestion about die brand?
i see many dies from carbon steel , titanium, ... and i am a bit confused.
there are sets of taps and dies to ebay from 10-50 $ . do you or anyone else have any experience with that kind of tooling?
thanks very much
achilles
rxAxilleas, I would advise not using the ball links if the thread depth is not complete ,which it wont be if you cut off end of the rod ,as the rod is smaller than the threads . The only 2 ways you should
do this is either use a solder on threaded end or get a fully threaded rod and cut to length . The later is not
recomended on giant scale aircraft if the length of the rod will be longer than 6 inches as the threaded rod
is weaker to flexing and side load than the regular rod that is only threaded on the ends . Another option
would be carbon fiber rods built to length.
do this is either use a solder on threaded end or get a fully threaded rod and cut to length . The later is not
recomended on giant scale aircraft if the length of the rod will be longer than 6 inches as the threaded rod
is weaker to flexing and side load than the regular rod that is only threaded on the ends . Another option
would be carbon fiber rods built to length.
What you can do is this (posted elsewhere here by Fred Messacar):
Quote:
The outside diameter of a 4-40 thread is 0.112. The outside diameter of a 2-56 thread is 0.086. The rod you are using (0.093) is larger than the 2-56 and significantly smaller than the 4-40. The 0.093 just will not allow sufficient material to form a proper thread for the 4-40 size.
For some time now I've been using 7/64" (0.1093) rod for making my own 4-40 rods as required. Granted, this is a difference of just under 0.004 on the diameter, but then cutting the thread is a little easier.
I've never, repeat, never had a 4-40 clevice or nut come loose and I've been using this method for about 10 years.
The threads where the diamater of the unthreaded portion is less than the threaded portion is due to the manufacturing process, which is commonly known to myself as "rolled" threads. This is where the metal is squeezed out of the valley of the threads into the peaks of the threads. The diameter of the unthreade portion will be approximately 0.076 while the diameter of the threaded portion wil be approximately 0.086.
Hope this helps.
The outside diameter of a 4-40 thread is 0.112. The outside diameter of a 2-56 thread is 0.086. The rod you are using (0.093) is larger than the 2-56 and significantly smaller than the 4-40. The 0.093 just will not allow sufficient material to form a proper thread for the 4-40 size.
For some time now I've been using 7/64" (0.1093) rod for making my own 4-40 rods as required. Granted, this is a difference of just under 0.004 on the diameter, but then cutting the thread is a little easier.
I've never, repeat, never had a 4-40 clevice or nut come loose and I've been using this method for about 10 years.
The threads where the diamater of the unthreaded portion is less than the threaded portion is due to the manufacturing process, which is commonly known to myself as "rolled" threads. This is where the metal is squeezed out of the valley of the threads into the peaks of the threads. The diameter of the unthreade portion will be approximately 0.076 while the diameter of the threaded portion wil be approximately 0.086.
Hope this helps.
Senior Member
HI,
thanks for the info!
i triyed already to cut the threads with a 4-40 tool and the 0.093 rod is useless!!!
the solution you are suggesting is a very good one. where can i find these 0.109 rods?
thanks
thanks for the info!
i triyed already to cut the threads with a 4-40 tool and the 0.093 rod is useless!!!
the solution you are suggesting is a very good one. where can i find these 0.109 rods?
thanks
Senior Member
I have used the rodchuck method for years. It uses 1/8 welding rod and you first cut a 5-40 thread, the re-cut a 4-40 thread.
Google....rodchuck.
Cheers, Dave.
Google....rodchuck.
Cheers, Dave.
