hand cranked vs chain mortiser

[esarratt]

I have a hand cranked mortiser.  And, I am about to buy a chain mortiser.

Is there any point in keeping my hand cranked mortiser?  If so, why?

[Jim_Rogers]

I use my hand crank boring machine to bore my peg holes through the mortise timber. That way the machine holds the bit 90° in two directions, left and right, front and back.
Some people bore the hole through the mortise timber before they use the chain mortiser to make the mortise.
Just be careful to not let the bit blow out a chunk on the bottom side of the timber as this is the showing face of the timber, because we bore the holes from the layout side, which can be the outside of the frame.
Recently, when boring peg holes we put a board on the bottom of the timber, held with a clamp, to prevent the bit from blowing out the bottom, which is another solution to prevent the peg hole blow out issue.
Jim Rogers

[esarratt]

Thanks Jim.

[Sugar]

For me it is a cool thought, that one could enter the wilderness with nothing but your hand tools.  And build!  

[esarratt]

Some people bore the hole through the mortise timber before they use the chain mortiser to make the mortise.

Why is it useful to do this?  Does it somehow make a cleaner cut?

[Jim_Rogers]

Some people bore the hole through the mortise timber before they use the chain mortiser to make the mortise.

Why is it useful to do this?  Does it somehow make a cleaner cut?

I'm not totally sure why. I have always done the hole after the mortise. But one reason could be that doing it after can have a stop in downward movement when the lead screw runs out of wood to pull itself down as it enters the mortise. Sometimes you have to push down a little to get the cutters to break through.
Doing the hole first there is no gap or stoppage of the downward travel of the bit.
That's about the best I can tell you.
Good luck with your projects.
Jim Rogers

[swmn]

Some people bore the hole through the mortise timber before they use the chain mortiser to make the mortise.

Why is it useful to do this?  Does it somehow make a cleaner cut?

As usual, Jim has it right.  Anytime a drill bit, auger bit, doesn't matter if it is Irwin, Jennings, brad point, all of them, when it exits the opposite side of the piece you are drilling there is a chance of blowout, taking out big splinters you didn't mean to remove.
If you mortise first you have two chances for blowout, one inside the mortise and the other on the opposite face of the timber.  If you drill first your mortise can wobble.
I tend to mortise first and then drill. If the grain is wonky or the timber is a problem child I will stop and think about it when I have my game face on.  This is one of those places where it is good to know all the techniques and have experience.  I prefer to cut my tenon cheeks with a rip saw, I think Jim prefers chiseling once the crosscut on the shoulder is done.  Maybe 80% of the time either is fine, but 10% of the time rip saw is the better choice and 10% of the time chisel is the better choice.  Maybe it's one third one third one third.  Whatever.  Know the techniques, go do, learn from your experience and then know.

[CJ]

 The way I was taught (not necessarily the correct way) and it has worked well for me is, I drill my peg hole from both sides of the timber after I have completed my mortises. I measure down from both sides using a square and mark my spot. I also measure from the end to the same spot. Technically, they should both align perfectly and there is no chance of blowing out the following side. I have had overall success with this method and have never had any hole that was out of line. But as I said, to each their own. 
 As for your idea of keeping the hand crank mortiser, if you feel you will use it down the road (should your chain mortiser break down) you will have it as a back up. It's also a nostalgic piece that is hard to find these days.
 I wish I had some extra coin kicking around to buy a chain mortiser! It certainly expedites the process of your build. However, I managed to get by with making my mortises with Forstner bits and a cordless drill press that I made that both plunges and the chuck rides on rails so I don't have to reposition my press. It does a great job and all I really need to do is use my corner chisel to square out the ends. Easy, peasy, nice and sleazy. 
 Whatever you end up doing, it will be whatever works best for you. Lots of good tips here.