Newbie- Clamping Inquiry - Long post - No Mentor

[JWB_Machining]

Hey,

I have a piece of cylindrical steel stock (Rockwell 24 C). It is 4" long total. 1.7" of this is 2" diameter, the remaining 2.3" is 1/14" diameter with .3" fillet. Well I don't have this piece but I will once I figure out my G-Code Problems. I might have to pull out Mastercam to make it since the Haas IPS output on my TL-1 is being problematic but that's another story.

Anyway my objective is to have a 1/4" hole drilled perpendicular to the 1 1/4" diameter section of the rod. I kinda need to be dead on this being centered perfectly and it being perpendicular is really important. I plan on using my Haas TM-1 to drill this hole. I still have to figure out exactly how I'm going to use the work piece probe to set the offsets so any suggestions on that would be welcome.

What I want to know is how should I clamp this? I'm thinking I should use my Super Spacer and just deal with the hassle of making it square to the table so I can set my offset right. But would clamping the 1 1/4" end in my vise be better? Or even clamping the 2" portion in my vise be better?

I feel like using the Super Spacer is my best bet and I'll just have to deal with squaring it up. If I go with this I should use the work piece to square it up right? It's pretty old and none of the surfaces on it seem smooth enough to get a good reading.

If I clamp the 1 1/4" this might be easiest and then I just have put some stock underneath it so i don't drill into the expensinve Kurt vises we have in which case my boss might slap me.

If I Clamp the 2" portion and start drilling i'm afraid the piece will begin to rotate because it's theoretically only being held by two lines (No area) 1.7" long and that doens't seem to rigid to me.

Order of operations Question: Maybe I should just drill the hole before I turn down the stock to 1 1/4"? Also Like I said I plan on using a mill. I'm going to center drill (No Spot Drills) then go into it with my 1/4" drill. Is this ok or should I do a small plunge with a 2 flute so I have a flat area to drill? Maybe after I use my fancy Haas to Denter drill I should just walk over to the drill press and finish the job or is that ill advised?

Sorry this is so long. If you don't understand anything or want pictures of my part or have completely better suggestions on how to drill this hole let me know. I'm leaving for the day but I'll check back here as soon as I get in tomorrow morning. I really do appreciate all the feedback, I had a great machinist to learn from at college but now I'm at my job where I'm lucky enough to have my own lil shop set up to work with but I'm right out of college and there's no one here to learn from so I'm shotting from the hip because every piece I work on is different.

[Geof]

The cheap and nasty way, but quite legitimate, is to lay it in the table slot by the larger diameter and then hold it down with a single clamp centered on the length of the large diameter. The table slot aligns it with the X axis and because it is nestled in the slot it is held firmly; you are only drilling a hole.

The better way is to have a good vise on the table with the jaws aligned on the X axis and a fixed jaw corner probed so you know where it is. Then grip the part across the jaws again you are only drilling a hole it will be held firmly enough. When the jaw corner position is known you can find your hole position relative to this just by measurement and do not even need to probe. Y is minus the part radius from the jaw and X is the distance from the jaw corner to the end of the part plus or minus the distance of the hole from the end.

[JWB_Machining]

I think I'm gonna with using a V Block that I align in the X and just using table clamps along the length, If I seat the part in the table itself I think the TM-1 would yell at me for a Z over travel. Shouldn't be a problem here right?

[Geof]

Originally Posted by JWB_Machining ..... If I seat the part in the table itself I think the TM-1 would yell at me for a Z over travel.....

Maybe, how close can the spindle get to the table? My TM3 gets to within 3 inches so with a holder and a tool you can touch.

The Vee blocks will work fine, you just have to align them to the table, my way is the lazy guys way.

[DareBee]

I would hold it in the vise in the 4" dim between the jaws and use a V-block parallel that is clamped to the fixed jaw of the vise for X centering. An end stop on the vise would also work well (instead of the V parallel) assuming your dia tolerance is consistent among parts.
Don't forget to centerdrill.