Making Rotary Table Accessories

[Chuck in E. TN]

I recently purchased a 4” Vertex Rotary Table without accessories. I’m in the process of cleaning, deburring, and making accessories for it. My first project is makeing a MT2 stub and adapt a copy of my 7X14 lathe  nose to it. I made the nose while trying to make a simple rotary table. The nose worked out, but the home made rotary table didn’t.
I need to adapt the nose to the stub so I can mount my lathe chucks, and even my face plate on the Vertex.
Not having an engineering background, I have a couple questions for the more experienced.
The unturned portion of the stub is .827”. The current hole in the nose is .467” I made it to fit the shank of a bolt I used to mount the nose on one end, and a 60 tooth change gear on the other, and it also fit the bearing I used.
Obviously, I need to make these two fit together. Should I enlarge the hole in the nose to say, .500, or larger, and turn the stub to fit the present hole? What would be the advantage of either, other than it would take less time to just turn the stub to a tight fit with the current hole in the nose. Is bigger better?
I don’t have any reamers, so I would have to make one out of drill rod (silver steel) which the largest I have is ½”. A bigger hole would mean boring.
Pics here:
http://s571.photobucket.com/albums/ss157/chucketn/Machining/Vertex%20Rotary%20Table/

Thanks in advance for your input.

Chuck in E. TN

[Bogstandard]

Chuck,

In cases like this, surface areas count more towards rigidity rather than hole sizes.

Also being able to true things up afterwards plays a major role in getting accuracy onto your tooling.

I gather that your lathe has a 2MT in the spindle, so that should cover getting the accuracy back after you have married the two parts together. Skimming up the face to run true after assembly.

I have done a C-o-C at the bottom to show what I mean about surface areas and how to get the best support for what you are attempting to do. I have shown two methods for locking things together for taking the pressures of use, grub screws are the preferred method. Machine the face flat in the lathe after everything is locked up tight.


Bogs

[Chuck in E. TN]

Thanks for the input Bogs. My lathe headstock is MT3, the tailstock is MT2. But, I do have a MT3 to MT2 sleeve.
I think I will bore the hole in the nose to .750, turn the end of the stub to a tight fit and add the grub screws as you propose.

Chuck in E. TN

[Bogstandard]

Actually, 3 equispaced grub screws would be better, and you would have no trouble holding whilst drilling, you just pop it into the RT, line up the join and stick a hole every 120 degs.

Bogs

[Chuck in E. TN]

I did what Bogs suggested. After turning the big end of the MT2 stub to .750", I bored the center of the nose adapter to a tight sliding fit. Put the whole mess on the Rotary table, centered it, found the join line and drilled and tapped 3 equally spaced holes for 8-32 grub or set screws.
I then took the adapter off of the RT, put it on my lathe using a MT3 to MT2 sleeve, faced the adapter and center drilled it to allow quick centering on the mill table. I need to  work on the nose part as when I tried a chuck on it in the lathe, it had a lot of runout. I thought it was much better than it turned out. Good thing I made it chunky, lots of material that can come off in trueing it up.
This was a great lesson in planning, process steps, and thinking ahead as well as trying to be as dead-nutz accurate as possible! Measure twice, three times if necessasary, then cut once and maybe do over! That's me! Thanks for your help Bogs and everyone else that has had input.

Chuck in E. TN