# Autocad?



## Chris Burton (Jan 3, 2013)

Does anyone here draw their pens with Autocad, or some other cad program? I have some questions about drawing threads and what kinds of tolerances need to be designed in. And probably a lot of other questions as well...

thanks,
Chris


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## cnirenberg (Jan 3, 2013)

Chris,
I found a lisp routine that drew in threads.  I can send you the routine if you want.  I basically just drew it in, scaled it to fit and know what size it is, and used it for all the threads in the pen. Looks good in the drawing, but does it matter if the threads are off, unless of course you are sending the drawings off to someone to use to make by hand.


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## Chris Burton (Jan 3, 2013)

Hi Cris,

Thanks for your reply. Does the lisp routine draw 'generic' threads, or are they exact such that I could send the file off to a machine shop to have them program their machine with it? 

At the moment everything I do is by hand on my lathe at home, but I'd like to farm out some of the grunt work in order to focus on other aspects of this stuff. Having the ability to draw up a cap/barrel/etc to be made in quantity elsewhere would be a big step for me.
I can hack my way through autocad well enough to draw the parts I need but for dimensionally accurate threads.

many thanks,
Chris
cbburton@gmail.com


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## cnirenberg (Jan 3, 2013)

Chris,
Still trying to find it in all my stuff.  Possibly on a jump drive. What you can do is, draw the tenon to scale with a hatch. Label it with the thread size and how many threads you want.  I'm not up to speed with the G code business or any computerized machining processes.  Best to ask a bunch of questions first.


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## cnirenberg (Jan 3, 2013)

Chris,
Check your Gmail.  I just sent you a drawing.


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## mredburn (Jan 3, 2013)

You might check to see what kind of files the shop you have in mind can accept. Some times importing cad files doesnt work as flawlessly as it should. Then they have to be redrawn. You might just need to give them a dimensioned drawing and they will do the cad/cam work.


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## btboone (Jan 3, 2013)

I draw my stuff in AutoCAD.  For threads, I just draw the 60 degree threads with the tops nipped off and allow some clearance, like .004" between male and female threads.  It depends on materials, tools, and other variables as to whether that will work well or not, but it's a good starting point.


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## Paul in OKC (Jan 8, 2013)

Drawing actual threads is not really needed. Just draw the diameter and call out the thread size. If the machine shop uses the drawing they still have to input info in when they program for cnc. If running manually, same deal. I use AutoCad all the time at work (and use it for projects!). When I open a drawing in the cam side, it doesn't see the threads. It cuts the diameter I give it and then the threads as I tell it the pitch and depth for that thread.


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## Denis McCarthy (Jan 11, 2013)

Hey Chris

Just noticed your post. I like to draw in Solidworks from time to time, which is a CAD program kinda like Autocad. What are you drawing specifically? Are you working on a new pen design? Also, Paul pointed out that you really don't need to draw the threads unless you just like the look of the threads in your drawing, so your model will look more like the design you have in mind. The actual specifications drawing that you submit to a job shop will need all of your specifications called out, including the threads and all of the deminsions involved, so they know what you want to have done. So, if your pen has 5/16 x 28 threads for the cap, you will need to point that out on your design. So what exactly are you wanting to draw? I may be able to help you.


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## Chris Burton (Jan 15, 2013)

Thanks for all of the responses (and the file, Cris).  I am slowly learning Autocad and am about to the point where the only part of the pen (cap & barrel) that I can't accurately draw is the threads. I'm not yet to the point of sending anything out for bid and I don't have a shop that I'm working with, although I do have a few in mind.

I'm just trying to figure out how detailed the drawing needs to be so that it contains everything that the shop will need and also has enough information so that I mitigate the amount of time that their guy has to spend working on it before it gets put into the machine.


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## mredburn (Jan 15, 2013)

I use Rhino and RhinoCam.


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## Tom_W (Jan 15, 2013)

Rhino to model if I feel it necessary...

CAD by itself is an interesting one - it really needs CAM to be useful. 

If you are only using CAD and are only making one off pens (rather than making a CNC batch) you are really just doing it for the sake of it. I suppose you could use the subsequent drawing dimensions on a dro on the mill and lathe.

If its a one off I draw it by hand - its quicker. 

Don't get hooked into trying to draw threads - just show the correct untapped/died hole/stub dimension and tell the engineering works what thread you want and how long it should be..  Most CNC shops have the programs for the threads already as Macros.

T


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## Paul in OKC (Jan 15, 2013)

I use cad for putting ideas to paper. It helps me think in more proportionate numbers and gives me a better 'ratio' of parts to each other. If you want to put threads on a part, just draw the 'tops' of some small triangles and mirror them, then connect with a line from one side to the other, diagonally over one instead of straight down. Clear as mud? Again this would just be for a visual effect, not for actual thread count in producing. That comes from the info given on the thread callout.  If I remember I will draw up one tomorrow and post.


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## Paul in OKC (Jan 16, 2013)

Here are 3 different ways to do threads on a drawing. The first one is how I generally do in a drawing for manufacture, and call out specs.


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## mredburn (Jan 16, 2013)

I used to use corel draw to draw in scale, there is another program that I use now as well called "Draw Plus" by serif thats pretty cheap if I want a 2d representation with dimensions added.


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## Chris Burton (Jan 16, 2013)

Thanks again to all in this thread. 



Paul in OKC said:


> Here are 3 different ways to do threads on a drawing. The first one is how I generally do in a drawing for manufacture, and call out specs.



Paul, thanks for the examples. So do you just call out 36 tpi and the length of thread?


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## Paul in OKC (Jan 16, 2013)

Chris Burton said:


> Thanks again to all in this thread.
> 
> 
> 
> ...



You would call out the diameter and number of threads per inch. Length will be the length of the 'tenon' unless you didn't want it thread full length, then specify how far back to thread.
For instance if it you wanted a 1/2-20, that is what you would put down.


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