Boxford Hmc full 4th,

Hello,
has anyone converted a rotary axis into a fully controlled 4th axis with a brake, it doesn't matter if it was on a lathe or mill or even making a 4th.
i have a boxford 165 Hmc and the table (a axis) has a ratchet wheel on the underside of the table and it only allows 1 way movement in 45deg increments so I want to strip off the ratchet and worm wheel and fit a disc brake and HTD timing pulley then mount the motor vertically with a timing pulley on the shaft, but before I start I have some questions,

if I got a bigger motor would it "hold" the axis in place during milling without having to fit a brake?

Would a stepper be ok or would a servo be better for the application?

if I fit a brake are my only 2 options either hydraulic or pneumatic?

i don't have any hydraulics on the machine is there a small system that can be installed or is air better?

Any info is good info thanks,
chris w.

Chris,

I converted a Nikon Indexer into a servo driven 4th axis detailed here :

http://madmodder.net/index.php/topic,9439.0.html

... it goes on a bit :)

Hi Chris
new to the forum, but thought that would chip in so to speak, I too have a HMC160 and I was wondering the same thoughts as your self re the 4th axis, I have at present a 4th axis fitted but not using the inbuilt 4th axis that rotates at 45 deg intervals...it is borrowed from a fried and this is a true rotary table with stepper motor fitted, same as the one from arceuro trade..

My thoughts are if the original 4th axis has a reasonable worm drive then by rights it should hold the pressure of the milling operation, however the play on the worm wheel is the main problem so to eliminate the play and then use the stepper to hold the table in theory should work...
I see what you mean about the brake as the original forth axis goes past the 45 deg point and then reverses to hold the table in place, thoughts on this is the table in effect is being held against the stops by the stepper motor and this reduces the play on the worm wheel and the table is rock solid so the original motor is holding the table in one direction against the cutting forces, and the stop in the other direction... Hence my theory if the play could be removed from the worm wheel then in theory it should hold the table at any angle....

I have looked at this may time and had the same thoughts just time on my side that is a little restrictive.

On HMC160 have also fitted 3 phase motor and inverter, plus using mach 3 and spindle feedback, still using the original sd stepper drives for all axis with an interface to the pc that I have built...

Good machine done loads of machining and works a treat...
Best regards
Paul

Hello Paul,
have you got some pics of the rotary table axis, how much stroke of the y axis have you lost having the rotary table mounted on top of the original table?
regards,
chris.

Hi Chris

I have lost about 70mm on y axis, that is to the top of the extra rotary table see arceurotrade part number 130-030-00300, and I lose a bit more as I have fitted a Jacobs chuck in the 2mt taper, all I needed to do was cut some gears, did work well. I will post a picture over the weekend for you...
I don't think it is the best way though! I would prefer to get the 70mm ++ back and use the original table.
Regards
Paul

Sorry, I haven't been on this site for a very long time. I have the same machine, No9 if its interessant. I have seen, the stepper drivers work with 5V-TTL and Step-dir like many normal stepper drivers.
Unfortunately, I don't know which gear ratio they use for the wormgear.
If you remove the ratchet and change it to a wheel with a Bicycle Brake or similiar, it should be no big problem, to use it bidirectional. But you must use the brake to clamp your rotary table.