Boxford Rotary table adaptor

[raynerd]

After purchasing my new 4" Vertex and reading Darrens thread on his adaptor I decided to make my own. This would be my first time cutting a thread of such a size and to be honest, my first thread of any meaning. It would also be my first time with a MT. I should have take more pics but Darren has loads and to be honest, better than mine so here it is complete, looks a bit like a dog has been chewing on it but I`m proud of it for my first attempt!



The adaptor was threaded so that it could be bolted and clamped down:



Now that I have the adaptor, here is the selection of boxford chucks I have available, not including the 4 jaw and a few other face plates



Always a but.... BUT .... no good yet as I have run out  and in this setup 0.015" !!! I guess this is not usable....



These chucks are really fat - I have very little travel left with this in place (although would have a little more with the collet chuck rather than the drill chuck in place)

So I don`t know where I have gone wrong, any advice appreciated!

Chris

[Darren]

Chris, no use measuring the outside of the chuck.

Chuck a bar in it and measure that....

[bogstandard]

Go to the bottom of the page on here and you will see they sell adapters for Boxford.

http://www.chronos.ltd.uk/acatalog/Vertex_Rotary_Tables_and_Accessories.html

Or go to my latest post to see how it is done

http://madmodder.net/index.php?topic=2002.0

[Darren]

I believe Chris already mentioned that whilst the Myfords were cheap enough not to bother making your own, for Boxfords he thought at the price this might be a good time to have a go for himself and learn something in the process.

At £36 quid I'd have to agree, but then I would at the Myfords price too as I'm a cheapskate ...

[bogstandard]

Don't get me wrong Darren, Chris asked for a solution, I showed him two possibilities. It is up to him whether he takes them on or not.

Unfortunately, the closer the tolerance you want to work to, the more it costs. Not just in monetary terms, but in time and experience.
 
If you haven't got either of those two, it starts to hit you in the pocket if you really want something.

That is just a fact of modern day life.


John

[raynerd]

Darren, yes - I see what you mean. Of course I`ll have to chuck up a bar and measure run out there.

[Darren]

Trouble is Chris it really does look like you are running out of room there?

By the time you add a cutter and your work piece it looks like you'll be about done.

[raynerd]

lol, did notice that !!     I still want to make it to complete the project but my use for the RT mainly involves mounting the RT vertical so will still be of use. Eventually I will get a small slimline front mounting chuck. I`m glad I didn`t go for the 6", I wouldn`t have fit the RT under never mind chuck and work.

[raynerd]

If only someone supplied a slimline rotary table..... 

[Gerhard Olivier]

Craynard you not only have to chuck up a piece but true it in the chuck on the lathe.  Then move the whole lot chuck and metal piece from the lathe to the RT.  Then check as self centring chuck have some runout of their own. Your run out may not be as bad as it looks.

Gerhard

[Darren]

Chris, I just noticed that you do not have a back register on your thread. This is what the chuck squares itself with. Without it your chuck is never going to be in line and square on threads alone.

Threads are not used to line a chuck up, just a method to fasten it. I think you'll have to make another spigot.

Make sure you machine the register and the thread in one hit withou removing the part from the lathe. After making that I'm sure you'll have a much better result.

Good practise anyway ...  

[bogstandard]

If only someone supplied a slimline rotary table.....

That would not have solved your problem.

I too have major clearance issues for some setups, and I have a much deeper throat on my mill.

Everyone is striving to fit a chuck on their RT, including myself, when in fact an RT is a lot more versatile than that.

The slimline one you were looking at was just too limited in the accuracy stakes, you may as well have used a lazy Susan with felt tip markings around the edge, and later, when you learn how to use the vernier hand wheel and dividing head, you will be thanking everyone for   you down the road of the one you have bought.

Oh! ye of little faith.

I have most probably only achieved a height saving of about 10mm by making my new backplate, but every little helps.
My biggest problem solver has been to use dedicated spindle collets instead of a collet chuck. They have saved me about 50 to 75mm in the fight against clearance issues. To such an extent, I very rarely use my ER collet chuck any more.
Also, people say, why do I need so many drill chucks? By using the smallest chuck for the drill that I am to to be using, I can save myself precious mm's when it comes to a tight for height setup.
I don't buy tooling just for the sake of it, there has to be a reason for it. The difference between the smallest and largest chuck is about 35 to 40mm in gained clearance. Maybe the difference between getting the job done or not.

So it isn't just your RT you have to look at, you have to scan the overall picture to achieve what you want.


Bogs

[raynerd]

John, I was only teasing regarding the slimline - I know the Vertex is much better. I went in and looked at them both side by side and the vernier scale and no wheel reading including absolutely no minute accuracy I imagine would really limit it.

Darren - "Chris, I just noticed that you do not have a back register on your thread" - the thread OD is 1.5" and if you look at the back of the threads there is a area none threaded and larger register at 1.75", the thread does butt up against it so I thought this would be OK. I will probably have to make this again with a bigger register. Before I do, I`ll take geroli`s advice and chuck a piece up on the lathe and transfer to the RT and re-test for runout.

Cheers
Chris

[Darren]

I think your register need to be bigger Chris, it is a bit on the small side.

[raynerd]

Yea, I totally see what you mean. If I`m being honest, the thread looks like something has been gnawing on it so could do with being done again. Certainly not a waste of time ... learnt a lot.

Thanks for your help and interest   

[raynerd]

Just looking at Stews thread on the Stephensons indexer - what about using a 2MT ER32 collet chuck straight down the MT of the rotary table. I`m not trying to get anyway from this adaptor, I still want to use my boxford chucks but I`m just thinking of additional ways of holding the work in the RT. I have a set of ER32 collets and 3MT chuck for the mill, but I`m guessing a 2MT chuck would hold work really securly in the RT as well. Am I missing something that would stop me doing this? I know I could use a 3MT - 2MT adaptor to use my current chuck but this would increase height above the table. The chuck is also pretty skinny so would fit nicely under the chuck. Obviously, limited to 20mm thickness but I`m guessing it would be a good way of holding work?

Chris

[kvom]

If you do get a smaller chuck, I suggest getting one with 2-piece jaws and making soft jaws for it.  You can very y make these shorter than the harf uppers and save some space that way, in addition to getting more accurate results.