10 Attachment(s)
Norman Toolpost 3. continued.
Hi Guys,
There are two things that need to be done before setting up to bore the large hole in the tool block.
Making this pin and drilling and threading it.
Attachment 375381
This is a drawing of the pin that is used to make the split clamp. Whilst I have shown the hole as 1/2" inch (12 mm) on the drawing, I didn't have any silver steel of this diameter, so I used 14 mm diameter, of which I have a full length of.
Attachment 375375
I cut a length of silver steel bar to fit into the 14 mm diameter hole that I had drilled through the width of the tool block.
I then faced off the ends.
Attachment 375377
The next step was centre drilling and then drilling all the way through with a 5 mm drill, the tapping size for M6.
Attachment 375376
After drilling I threaded both ends the full length of the tap. Later It is going to get cut in half anyway. And one half is going to be drilled to clear M6.
Attachment 375372 Attachment 375373
This is after checking and cleaning the swarf out. I used the threaded rod to clean the threads, since all the tapping swarf gets trapped in there.
Attachment 375374
The pin was a little over length, in this case 17 thou. So I took an 19 thou cut off one end. (No that isn't a typo) There is a good reason for doing this. That pin is going to get machined when I bore the large hole for the mounting post. The pin is a loose sliding fit in the hole. It will drop through smoothly without being sloppy.
At this point I seem to have lost the pictures of setting the tool holder block up in the four jaw. Sorry about that ! :o
All the excitement of using my new dial gauge holder and wobbler pin.
Attachment 375380 Attachment 375378
Here you can see how I secured the pin into the tool block to secure it for boring. The pin will get a hollow machined into it exactly the same diameter as the hole. That nut you see is just on short bit of threaded bar, it does not go all the way through. There is a large washer on each side. The idea is to clamp the pin securely in place. Now you can see why I machined a couple of thou more than needed from the end of the pin.
That boring bar is over a hundred years old ! It was given to me by an old mentor. Apart from being touched up now and again it leaves a great finish, and is very rigid.
Attachment 375379
Another picture whilst cutting. I don't care for taking pictures this close to running machinery.
More Later:
Thanks Guys.