Printable View
Hi
Question - when using the fixed steady . What is the prefered method of aligning the long work piece with the headstock spindle and the missing tailstock centre ? As there isnt a tailstock, how do you centre the piece within the three supports ?
Mike
A little bit more info would help.
Is the bar black or bright.
Are you using a 3 or 4 jaw chuck.
How long is the bar,will it fit between centres.
OKQuote:
Originally Posted by pipeclay
The question is a hypothetical query . In this example , the bar will not fit between centres , it is bright steel and the chuck is 4 jaw .
Thanks
Mike
Use a shorter piece of bar at the same diameter as close to the chuck as possible with bar running true in spindle. Set the supports to the diameter. Move steady to required distance away from chuck.
Really you could say the bar itself is too big for the machine.
If it had to be done one method would be to adjust 2 of the 4 jaws too near the correct od of the bar,
place your steady in the desired position with 2 of the 3 fingers adjusted to near correct od of the bar.
With the weight supported by the 2 jaws of the 4 jaw and the other part of the bar supported by the
2 fingers of the steady adjust the other 2 jaws of the 4 jaw until they are touching the od of the bar.
You could know set your indicator up near the chuck,2 indicators would make it a bit quicker.
If only using 1 indicator bring it in to touch the bar near the chuck and adjust the jaws of the chuck
until the bar is running fairly true,now go to the end where the steady is,probably easier to do the
outboard end of the shaft and adjust the 2 fingers until the bar is fairly true.
You would need then to return to the chuck end of the bar and probably readjust the jaws again
this time trying to get the bar running true,you would then need to return to the steady end and set it true.
You would need to repeat doing this until you are happy with the setup,then you could close the steady
if it has been left open and adjust the 3rd finger whilst the bar is turning until the 3rd finger touches the bar.
I can't say i agree with Peter, although i may have missunderstood what he is describing. It does not mater where the 2 fingers of the steady are, the bar will run true when dialed (as long as the bar is round) I have used the method clubman described, otherwise you need to clock along the length of the bar for both X and Y axis (using Y, Height and X, Front to back to make it easier to understand hopefully) Do the Y first as the top finger of the steady can be set and left whilst you do the X with the other 2 fingers. Unless the bar was way out in Y the X should still be ok.
The problem with this is that the saddle has to be on the head side of the steady-probably not where you need it so the steady must then be removed and replaced to get the saddle on the T/S end of the lathe.
The other way is to dial in the Y of the bar with a clock in a stand running on the rear flat way, up against the v way. Then the X can be set as good as possible, and a few test cuts taken on the end of the bar. The test cuts will show if the lathe is cutting a taper and therefor the bar needs to be moved either forwards if the end of the bar is big, or back if the end of the bar is small.To do this of course you need to have some excess material in diameter to make the test cuts.
On the subject, what is the preferred method of lube for a steady? I have always used oil but watched a vid the other day where the operator used grease.
Depending on the type of fingers you have would depend on lube if any.
No harm in using oil or grease,white lead was also common,roller fingers would be best.
Not sure if I understand fully about your z and y.
Have set quite a few long jobs up without the use of a sample from 500mm to 3mtrs using that method.
Y as in height and X as in front to back......
My fingers are bronze. I find the oil gets hot and simply runs off the job and all over the bed of the lathe. I didn't think that roller bearings would work so well on a metal lathe (i've used them on a wood lathe) I have no reason why other than i have never seen them so i guess i figured there must be a reason.
Hi Mike,Quote:
Originally Posted by morrisman
All I do is put the bar in the chuck and clock it until the bar is running true then bring the fixed steady fingers up to meet it. Care should be taken at this point as finger pressure can push it too far out of truth. The bar should be self supporting enough on its own as you only need the steady when machining.
HI Ewan,
with regard to the X Y and Z axis I hate them as I can never remember which is which:D but I think on a lathe the Z axis is the longitudinal one and there is no X axis...I think. I stand to be corrected.
I have also used steadies with bearings mounted on the end of the fingers and found them to be a handy addition to the point that you would wonder why they weren't made that way from day one.
Hope this helps Mike.
Phil
Lathe axis
z is longitudinal as it runs parallel to the spindle same as a mill or drill and x is usually cross travel but not always in most cnc machines its referred to as x
cheers
Harty