Two Piece Mill Vise

If it were me, I would use something larger than 0.375" drill rod for my guides. If you look at the amount of meat inthe Kurt vice side guides that should give you an indication of the forces that you are trying to control. Especially when you might not have a work piece that goes the entire with of the jaws.

For the drilling operation, I would do it in steps. The first step, I would use a short drill which will serve as a guide for the following steps.

I think that your operational steps are just fine. I like the idea of running the first <0.001" reamer through both using the mill and then the final >0.001" reamer through the stationary piece, also using the mill to ensure alignment, without breaking them down. You may have to do some final clean up on the stationary piece but it keeps everything aligned for the majority of the work.
 
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Hmm. I'm all setup for 3/8" drill rod with the under and over sized reamers. Now, you got me thinking. 1/2"?

I do have 3/8" and 1/2" shoulder bolts which I understand is harder and stronger than drill rod.
 
If I had a choice, I would go with 3/4" but you may be fine with the 1/2". Are the 1/2" bolts true enough to provide the alignment with the stationary part that they will be passing through? It may be worth the effort to validate and maybe even take a clean up pass on them to ensure they are as perfect as you can.

If you are going to use bolts, would you have them thread into the moveable jaw or just cut them off and press them in? If you thread them, you can always upgrade them if you need to much easier than if pressed.

I just have a tendency to over build things. Partly because I am not gentle at all. You can always make them larger if needed down the road.
 
I may have to stay with 3/8" since the reamers for 1/2" and 3/4" are too long to get under my mill's Z-axis. I guess I could go with hand reamers if I had to, but they seem to cost twice as much.

Remember that this is for a PM25 mini-mill and I tend to take light cuts.

Is this the proper drilling sequence:
  1. spot drill
  2. drill 1/4" with screw machine length bit
  3. drill with 1/4" jobber length bit
  4. drill 23/64" screw machine length bit
  5. drill with 23/64" jobber length bit
 
It was mentioned earlier in this thread that I shouldn't rely on tapped holes for tight tolerances. So, I plan on doing a press fit.

If I use the shoulder bolts, I would cut off the threads and press them in.

Is there a way to remove a press-fitted rod? How would you pull it out?
 
I should have asked the scale. For a mini I think you will be fine. Sorry to derail you.

Your sequence for drilling is fine. The final drill, 0.359 (23/64") might come out a little larger in the final hole. But given that by the numbers that should give you 0.016" (0.375"-0.359"=0.016") to ream out you should have enough extra to cover that. Clear chips often so that they don't enlarge or gouge the sides of the holes. Also, once you get into the first block with the last bit, you can double check what size you are ending up with before you go to far. Just in case you have to adjust sizes.

"Is this the proper drilling sequence:"
  1. spot drill
  2. drill 1/4" with screw machine length bit
  3. drill with 1/4" jobber length bit
  4. drill 23/64" screw machine length bit (If you have a gauge pin, good time to check final drill dimension)
  5. drill with 23/64" jobber length bit
  6. Ream small dimension through both pieces
  7. Ream larger dimension through stationary piece
 
Thanks. I don't have gauge pins, but I measured the drill rod to be 0.3751". That will have to be my gauge pin!

I have spiral flute chucking reamers so I shouldn't get much material in the bottom of the hole.

What's the preferred method of using reamers? I've only used one once before. I understand you shouldn't peck, but go straight in and straight out? Also, don't dwell?
 
I am no expert by any means, I pull often to clear the chips. Reamers, even fluted ones have a tendency to build up chips on the cutting points because we are generally removing very little material and without the larger chips, they don't seem to flow up the flutes. I have used straight reamers where this is compounded.

I not only clear the reamer of chips, I make sure to blow out the hole as well to make sure I am not grinding the chips into the surface.

Lubrication is very important. I like the Anchor Lube as it is a heavy paste and stays in place as long as there isn't a high heat. But any good cutting oil like Tap Magic will do.

Just take your time. You will be fine.
 
Okay, holes have been drilled and reamed. Everything went pretty smoothly. I get a nice pop when I pull out the test guide rod!

I had some chips in the bottom of the holes when I was trying to ream them. I tried compressed air, but it didn't get them out. So, I used a long thin magnet and *poof* all the chips came out!

So, now I need to press the guide rods in. Should I keep the two pieces together or separate them? I like the idea of keeping them together for alignment, but I'm afraid it may bind if not perfectly aligned. Then, I'd be cooked and unable to separate them!

Thanks!!!
 
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