A few general newbie questions

[sigipa]

Hello All,

I am anxiously awaiting my new Syil Super X3 mill and C6 lathe. I have been reading just about everything I can find on the topic, but there are a few things I'm not quite sure about.

1. How do you know what the parameters are for creating large diameter threads so that they will be compatible with a particular screw or nut? Is there a spec for this somewhere that can be used in a CAD program?

2. What is the best way to create threads inside of a large diameter hole (1.5" for example)?

3. How do you cut a key slot inside of a hollow shaft?

4. What is the best way to align the work piece on a mill when you will need to move the work piece to deal with mill size restrictions?

5. What is the best way to drill/tap hole on the edge of 1/2" plate?

Any advice will be much appreciated.

Thanks,
-S

[JROM]

I'll try to answer your questions in order.
1/ Go buy a Machinery's Handbook. It's a fat green book that has the numbers on any thread you might want to cut. That book was the first thing they made me buy when I started in the trade.

2/ you have to single point turn it in a lathe, if you can't get a tap.

3/Use a broach and a broaching bushing......look it up in the book!

4/Get some dowel pins that fit your tee slots on your mill table.

5/ Use a large angle plate and hang the part off the back of the mill table, then swing the mill head around over the part.

Good luck!!

[bluechips]

I hate to sound like an old timer, but for "3. How do you cut a key slot inside of a hollow shaft?" (I interpret as internal keyseating) and jrom's method is easiest, however If you have a shaper, this is a good excuse to use it.
I've done it on a lathe, and a mill also (manual, not cnc) and this procedure is a pita , only to be resorted to in emergency situations, or by the very,very cheap. (too frugal to dish out the money for a broach set + press.)
My brother got a used American made DuMont set of broaches and bushings for < 100USD. But he's almost a mile away, and his set doesn't cover metric, so I often end up using the little shaper for this task.
Now, if you HAVE to do it on a cnc mill it can be done, assuming you can orient the spindle precisely, and lock it there. This procedure is strongly discouraged and I would suggest using jrom's broaching method.
But, if the spindle can be oriented, and locked, it is theoretically possible to (get ready to cringe folks) use the z axis to "emulate" a shaper's ram.
A single point key seating tool (looks similar to a boring bar) with a properly ground tool bit is "pecked" with very conservative feedrate to produce the internal slot.
Who would do this? Not me. Unless I HAD to have the internal keyway right now, regardless of the costs and risks.(and who has ever actually been in that position?)
Again, listen to jrom and get a broach set!

Or, to mollify the more enlightened, an edm machine (what can't they do?)

sigipa, PLEASE don't use the method I described to cut internal keyways on your brand new machines! It is only offered for theoretical curiosity.

Now, to make a long post even longer, if you are a hobbyist , you could consider using your new mill and lathe to build either an internal keyseater, or a metal shaper. But these are tools you will not be using very often*, and jrom's approach is again the wiser one.
* a shaper only seems indispensable to someone that has one.

[bluechips]

This guy needs help. He may not be in the right forum to get it. I would suggest that he be pointed to a basic machining how-to site. I don't know of any. Several members have expressed (correctly) that many new cnc'ers want to jump into programming without ever cutting a chip manually (my apologies to sipka if he has more experience than his post implies). This is a re-curring theme. Some of us (older) guys may not identify with this phenomena, since we were exposed to manual machines years before we ever saw a cnc. If you remember how fascinated you were when you first saw a long chip coming off a steel bar in a lathe in your youth, imagine how much more fascinating it would be to see the same thing, but no person operating the machine?
Its a combination of what amazed us, years ago, PLUS the added factor that a computer is actually doing/making something.
It is my belief that it would be easier to teach a 70 year old machinist to program,set-up and operate a cnc machining center than it would be to teach the same to a (typical) 20 something computer programmer. No offense intended to either age group, or either profession.

[sigipa]

Hi,

I appreciate everyone's input. JROM: I've been doing a lot of reading, but I missed this book somehow. Wow... what a resource. I wish I would have known about it sooner. Thanks very much for the pointer.

You are all absolutely right. I have absolutely no clue what I'm doing. However, as near as I can tell, my project needs don't required anything that would be considered particularly difficult fabrication wise. I have purchased a bunch of scrap metal. My plan is to draw up my parts, send them to the machine, and keep reading and tweaking until I am able to produce all of the features that my parts need. If I have to go through a few hundred pounds of material and tools to get there, so be it. Damn the torpedoes!

Many thanks to all,
-S