Representation of four start thread and manufacturing
Representation of four start thread and manufacturing
(OP)
Hello Everyone,
I have couple of questions on a four start thread. I have a bolt and a female four start threaded part which has to be represented in drawings. I was just wondering whether there is any standard for representing a four start thread on both male and the female part. It is a 1/4" dia bolt with 20 threads per inch (measured pitch) it looks like a fine thread. So can anyone enlighten me with the standard representation in drawings for these four start thread.
My second question is, if this part is to be manufactured, is there any standard taps & dies that are available for 4 start threads, if yes, can you please provide me with manufacturers for this. Or Is there any standards or any other process to be followed for while manufacturing these special threads? Thanks in advance for all you help.
Adios
Sandy
I have couple of questions on a four start thread. I have a bolt and a female four start threaded part which has to be represented in drawings. I was just wondering whether there is any standard for representing a four start thread on both male and the female part. It is a 1/4" dia bolt with 20 threads per inch (measured pitch) it looks like a fine thread. So can anyone enlighten me with the standard representation in drawings for these four start thread.
My second question is, if this part is to be manufactured, is there any standard taps & dies that are available for 4 start threads, if yes, can you please provide me with manufacturers for this. Or Is there any standards or any other process to be followed for while manufacturing these special threads? Thanks in advance for all you help.
Adios
Sandy
RE: Representation of four start thread and manufacturing
Can I get any help from this group for the above issues? I'am badly stuck up with my design coz of this. Appreciate any response on this.
Thanks,
Sandy
RE: Representation of four start thread and manufacturing
the full depth threads. If a tap with
4 thread lead cuts the threads,
you want to tap the depth of full thread.
Why do you need to show the excess
partial thread?
RE: Representation of four start thread and manufacturing
And my second question is (I'am repeating this!) if this part is to be manufactured, is there any standard taps & dies that are available for 4 start threads, if yes, can you please provide me with manufacturers for this. Or Is there any standards or any other process to be followed for while manufacturing these special threads?
thanks,
RE: Representation of four start thread and manufacturing
RE: Representation of four start thread and manufacturing
If I understand you correctly you have a 1/4"-20 thread with a 4-start...(5) turns of the screw advances the nut 1"? I think this is a VERY bazaar thread.
Functionally you would get the same movement with a 1/4-5 ACME (which is not standard)...but a 1/4"-4 ACME is. Actually 1/4"-4 is really 1/4"-16 with 4 starts according to my favorite ACME supplier. www.nookind.com
Your thread would be very fine and EASILY destroyed while an ACME thread is far more robust. If you would use a standard thread angle for your thread it would barely turn without locking up, much less supply any clamping force.
Please explain yourself more and explain why you would want to use such an animal.
I would suggest trying to use comercially available threaded rod and nuts since machine shops really charge a premium for this type of work.
RE: Representation of four start thread and manufacturing
.250-20UN-2A 4 start thread
.200 lead .050 pitch
Major Dia .2489/.2408
Pitch Dia .2164/.2127
I would use the UN designation trying to show a Unified Thread Form and the 2A to reference the tolerance range that I would want. I would then show the actual tolerances so there would be no questions of what you want. This may be not the proper method of calling out this thread but it will be understood by any competent machinist or supplier.
RE: Representation of four start thread and manufacturing
Some examples:
http://www.westerntap.com/
http://www.regalcuttingtools.com/special_taps.html
http://www.e-taps.com/
http://www.balax.com/
RE: Representation of four start thread and manufacturing
For 60 deg inch threads, the thread designation should include, in sequence, the nominal diameter in inches, the number of threads per inch, the letter symbol of the thread series, the number and letter of the thread class, and any qualifying information. For multiple start threads, replace the number of threads per inch with pitch in inches (P), lead in inches (L), and the number of starts in parentheses. An alternate designation method for multiple start threads retains the number of threads (pitches) per inch and adds lead in inches (L) and number of starts in parentheses following it.
Example:
Standard Unifìed Multiple Start Thread, Gaging System 21
.750-.0625P-.1875L(3 STARTS)UNF-2A(21)
or
3/4-16-.1875L(3 STARTS)UNF-2A(21)
RE: Representation of four start thread and manufacturing
RE: Representation of four start thread and manufacturing
For those of you that are saying that this is a wierd thread, you are right, but I have seen much stranger ones. I actually was involved with a #10 four start thread that a customer wanted to use to speed up their assembly process (imagine: only one fourth numbers of rotations to seat a screw! What speed!). We were able to make the screws (roll thread dies from Reed) but the application didn't work well because the helix angle was so steep that the parts are terrible loosening issues.
(Tried to tell him.....)
There are a huge number of double helix threads in use. Many of the special plastics threads are double helix (HiLo and Twin helix Plastite are two examples).
Dick
RE: Representation of four start thread and manufacturing
It sure is a strange thread, but as Screwman said, there are even more wierd ones in the market!
Thanks again group,
adios
Sandy
RE: Representation of four start thread and manufacturing
RE: Representation of four start thread and manufacturing
I measured the pitch by counting the number of threads per inch. So there were 20 threads per inch, but, they were 4 starts. So it meant, it had only 5 threads per inch from one start. Hope this makes sense. I wonder why you would say that it would be a 1/4-80, 4 start.
Hope this clears everything.
Thanks,
Sandy
RE: Representation of four start thread and manufacturing
I had seen your comment, when you said it looked like a fine thread. And a pitch of .200 to me doesn't look fine.So I was just running some numbers and came up with the 1/4-80, 4 start, which would have a pitch of .05, which to me would be a functional equivalent to a 1/4-20.
Funny thing is I found this web site because I am looking for information on a 6 start thread, so I have found all the comments great. I am trying to layout a Metallic Drive screw, #00, and get some screws made by Monday.