Norman Patent toolpost

[Chinggis]

Many years I hate when I work with my lathe and when I need to change tool for new one I need to play with shims. There is not enough shims or they are to thick. On Pinterest I find how to make QCTP Norman patent toolpost. So I try and there is results from my work.

This is drawing what I made with some modifications. There is one modification what is not in drawing and I think it is critical for qctp to work correctly. When I made this toolpost, I find that it hard or almost impossible to secure it to central column. So I make modification to original drawing, I bore two holes and with saw cut material to hole. I made two holes, but it works nice with one.

 

[Chinggis]

First Norman toolpost what is not successful at all. I try to make them useful, but I failed. One of reason why I am not be able to make them useful, is that my lathe is not able to "produce" exact tolerances what are needed. I mismatch it by 5hundreds and it is to big tolerance for bolt to tight.

 

[T Bredehoft]

You can buy small hones (brake cylinder service) that will hone up to 1.00, Make your hole just a bit small and chuck the hone in your lathe, spin it inside the too-small hole for a while with a bit of oil and you'd be surprised how accurate you can get.

 

[Chinggis]

You can buy small hones (brake cylinder service) that will hone up to 1.00, Make your hole just a bit small and chuck the hone in your lathe, spin it inside the too-small hole for a while with a bit of oil and you'd be surprised how accurate you can get.

Can you explain to me a little bit more "simple"? I think that I get what you want to tell me, but I ask you for more explanation Thank you sir!

 

[T Bredehoft]

Starting with a bore that is just not quite big enough, chuck the hone in the lathe (they are mounted on a flexible shaft) collapse the hone stones to fit inside the bore of your tool holder, with a bit of oil just to lube the process, and turn on the spindle, holding the tool holder in your hand. Go slow at first, and be careful that you don't move the tool holder so much that the stones escape the bore. It doesn't take long to remove a couple of tenths, stop the spindle and try it.

Hope this helps. Just one of many tricks of the trade.

 

[Chinggis]

Starting with a bore that is just not quite big enough, chuck the hone in the lathe (they are mounted on a flexible shaft) collapse the hone stones to fit inside the bore of your tool holder, with a bit of oil just to lube the process, and turn on the spindle, holding the tool holder in your hand. Go slow at first, and be careful that you don't move the tool holder so much that the stones escape the bore. It doesn't take long to remove a couple of tenths, stop the spindle and try it.

Hope this helps. Just one of many tricks of the trade.

Thank you on good explanation, I find on Google how it is done . Thank you again!

 

[martik777]

Are you saying you cannot bore the 25mm hole to within .050"??? If that's the case the lathe is not going to be very useful anyways.
I bore mine to within .003" and they work great

 

[ericc]

Are you saying you cannot bore the 25mm hole to within .050"??? If that's the case the lathe is not going to be very useful anyways.
I bore mine to within .003" and they work great

I think he said "5hundreds". In some parts of the world, this isn't all that much, like 0.0019". One should be able to do better on a decent lathe, but if that is all one has to work with, the tool holder may need more of a hinge (hole with a saw cut).

 

[martik777]

Of course, 5/100 x .039 but if he's that close it should tighten down easily

 

[mickri]

This will help you out. https://www.hobby-machinist.com/threads/norman-style-qctp.79705/ Covers all of the problems and fixes that I ran into in using my norman QCTP.

The key to getting a good tight fit between the post and the tool holder is to make the post longer than you need. Part off the extra length to use as a pin to test the fit on the holder. You want the pin to be almost a press fit into the bore on the holder. When you cut the slot the bore will open up a tad and through use it will open up some more. Also an 8mm bolt is barely adequate to clamp the holder to the post. You will need a class 8 bolt if you use an 8mm bolt. A 10mm bolt is better.