Get an indicator mounted to the chuck, and rotate the indicator around the quill of the tailstock.
I mean rotate the chuck where the indicator is mounted to.:rofl:
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How Level Does a Lathe Have to Be?
- Thread starter Allan
- Start date
Get an indicator mounted to the chuck, and rotate the indicator around the quill of the tailstock.
I mean rotate the chuck where the indicator is mounted to.:rofl:
Indicator in the chuck is a good way of indicating the tailstock spindle in. Another way which can give pretty close results is to put a very sharp tipped center into both the headstock's spindle hole and the tailstock's spindle hole(most call it the ram). Then,bring the 2 centers nose to nose and look straight down on them with a magnifying glass to see if they line up perfectly. BEST LOCK the tailstock down and lock the ram,too before doing this.
You can also check from the side view to see if they are at the same height. The tailstock may be low if it is worn. You can shim between the tailstock and its base casting. The tailstock ram must be parallel to the lathe bed for this to work,so run an indicator along the top of the ram by sliding the tailstock beneath it. Keep shimming till the tailstock ram is both at the right height,and parallel to the bed. Can be a vexing job,but needs to be done.
If you are careful and use a magnifying glass,you can get the tailstock to within .001" doing this.
You can also check from the side view to see if they are at the same height. The tailstock may be low if it is worn. You can shim between the tailstock and its base casting. The tailstock ram must be parallel to the lathe bed for this to work,so run an indicator along the top of the ram by sliding the tailstock beneath it. Keep shimming till the tailstock ram is both at the right height,and parallel to the bed. Can be a vexing job,but needs to be done.
If you are careful and use a magnifying glass,you can get the tailstock to within .001" doing this.
Re: How Check Tail-Stock
There is couple of better methods to test the tail stock alignment. I know some of you use the method George mentioned but this is the method I tell people to use.
I would not indicate the center of the quill unless you know how much the bar and indicator sags so you can calculate the mis-alignment better. With rod or mag base mounted on the chuck as the indicator will always drop or sag when it is turned over. There is a very simple method to prove this. Mount the mag base on a flat piece of bar stock say 1" x 3" x 10" and extend the indicator (think of a clock and the top is 12:00) out as far as you can go and put 1/2 turn of pressure on indicator and zero it. Flip the bar stock upside down ( 6:00) and check the error. Also read the indicator at 3:00 and 9:00 and the indicator will be moving all over the place. There is a indicator called a Co-Ex that you will have better luck with as it is designed not to sag. I would just use the method below though.
With this factor know mount the same rod in chuck or mag base on your chuck and check your spindle and subtract the error you had from the bar. (be sure you have the indicator rod set at same length,) You will get less deflecting error the closer you can mount the indicator to the TS your checking. The best method is to measure the OD of your tail stock quill and chuck up a round bar stock in your chuck that is bigger diameter then TS quill and turn it down to the same size.
Then move TS up as close to the HS test bar with TS quill out 3/4 of the quill travel and lock quill and TS down to bed. Then mount a mag base to cross slide or compound and check the side of test bar and quill to be sure they are aligned side to side. If they are off adjust TS sideways to match your HS test bar do a top dead center test of HS test bar and move saddle down to TS, not touching mag base and indicator and do top dead center test of the quill to check if the centerline or TS is same height as HS centerline. Then move the saddle and check TS quill to see if it is TS is parallel to centerline.
Then check the top of the TS moving saddle down the quill to see if the TS is pointing parallel to HS centerline. The majority of the time the TS is pointing down and low because the dirt gets under the front. You may also want to check the ID hole of the TS to be sure it is not burred and the taper shank of TS chuck or drill bit. Check this with new drill with ground taper. Prussian blue the drill and rub it in side the hole and look in there with a flashlight. If you find the TS low and pointing down tell us and I will tell you how to correct this. Good luck.
PS: I am a Journeyman Machine Tool Rebuilder and teach Machine Tool Building for several new machine builders. I use the above test when Rebuilding machines. The best method is to use precision ground test bars, mounted in the quill center hole, but they are expensive.
There is couple of better methods to test the tail stock alignment. I know some of you use the method George mentioned but this is the method I tell people to use.
I would not indicate the center of the quill unless you know how much the bar and indicator sags so you can calculate the mis-alignment better. With rod or mag base mounted on the chuck as the indicator will always drop or sag when it is turned over. There is a very simple method to prove this. Mount the mag base on a flat piece of bar stock say 1" x 3" x 10" and extend the indicator (think of a clock and the top is 12:00) out as far as you can go and put 1/2 turn of pressure on indicator and zero it. Flip the bar stock upside down ( 6:00) and check the error. Also read the indicator at 3:00 and 9:00 and the indicator will be moving all over the place. There is a indicator called a Co-Ex that you will have better luck with as it is designed not to sag. I would just use the method below though.
With this factor know mount the same rod in chuck or mag base on your chuck and check your spindle and subtract the error you had from the bar. (be sure you have the indicator rod set at same length,) You will get less deflecting error the closer you can mount the indicator to the TS your checking. The best method is to measure the OD of your tail stock quill and chuck up a round bar stock in your chuck that is bigger diameter then TS quill and turn it down to the same size.
Then move TS up as close to the HS test bar with TS quill out 3/4 of the quill travel and lock quill and TS down to bed. Then mount a mag base to cross slide or compound and check the side of test bar and quill to be sure they are aligned side to side. If they are off adjust TS sideways to match your HS test bar do a top dead center test of HS test bar and move saddle down to TS, not touching mag base and indicator and do top dead center test of the quill to check if the centerline or TS is same height as HS centerline. Then move the saddle and check TS quill to see if it is TS is parallel to centerline.
Then check the top of the TS moving saddle down the quill to see if the TS is pointing parallel to HS centerline. The majority of the time the TS is pointing down and low because the dirt gets under the front. You may also want to check the ID hole of the TS to be sure it is not burred and the taper shank of TS chuck or drill bit. Check this with new drill with ground taper. Prussian blue the drill and rub it in side the hole and look in there with a flashlight. If you find the TS low and pointing down tell us and I will tell you how to correct this. Good luck.
PS: I am a Journeyman Machine Tool Rebuilder and teach Machine Tool Building for several new machine builders. I use the above test when Rebuilding machines. The best method is to use precision ground test bars, mounted in the quill center hole, but they are expensive.