How Level Does a Lathe Have to Be?

Thanks, George and Pacer.
The head stock end has 4 holes in roughly a square layout. Pacer, that is one slab of a lathe! No wonder it only has two holes! My bed looks like limp spaghetti in comparison. Have you done one of the bar turning tests to see how it behaves?

Al
 
Hi: leveling and tramming is very touchy, you can chase the machine all over the floor!
For years I have installed print presses and bindery machines ( much larger than these lathes but the principle is the same).
The footing and the floor are the most important. The presses would have a 18" to 24" deep full floating slab 5000lb strength per square foot and cured at least 45 days.
If the floor as with any base it must be able to support the load. Garages and basements can have 4-8" of a concrete base usually never though to hold up a machine on 3-6 points each with a load of thousands of pound per fraction of a square inch at the mount points. The concrete is calculated in pounds per square foot.
Full floating is necessary! while walking, driving fork lifts, moving a band saw or your stock rack and loading the lathe or any machine these flex the floor. When you are taking the twist out of a machine using the anchors while leveling you are also twisting the floor per-say! They all are factors in the level and tram.
Don't drive yourself crazy making the level perfect you just want it flat, level within reason.

Striving for the best test using the round bar and machining both ends between centers.
Don't over-tighten the anchors! their only for holding it in position. If you feel it important to torque it down to all that the anchors can hold! Put your precision level on the ways when you do it.
As you tighten and loosen watch the level bubble run! I'm not talking about a carpenters level only a machinists precision.
When you use the level never touch the metal or the level glass only by the plastic finger grips. The heat from your hand or finger will throw off the accuracy for up to 15 minutes.
The final leveling take your time between level moves and to place the level back in the same spot use a Marker for referencing. I bored you enough some time I explain how to adjust the old machinists Starrett "98" on a flat surface-not level!
Just my 2 cents worth
dwdw47
 
Let me throw in my two cents on the subject. As several have already mentioned, you need to start with the base. What ever the lathe sits on it has to be stable. Most of the lathes we use are very limber. No casters and other such conveniences, when you finish aligned the lathe you cannot move it unless you want to realign it. Once you have a stable base that will insure that any alignment changes you make will stay then you can move on the aligning the lathe spindle with the bed and the tailstock with the spindle.

The easiest method that I have found that is fast and accurate is the "Rollie's Dad method". This method side steps many of the steps that would be followed by a professional doing a complete alignment but for the hobbyist it is fast and accurate. Since most of us do not have the measurement equipment that a pro would have we have to make do with what is available. Here is a link to the PDF of the procedure.

http://www.neme-s.org/Rollie's_Dad's_Method.pdf

Most hobbyist would be very surprised how the misalignment of there lathes result in work that is far from what they envisioned when starting a project. Taper can be a project killer, turning the perfect cylinder is always a challenge.

Jim
 
Thanks DW and Jim.
Stability is why I had a steel frame bench made up rather than use the wooden on that came with the lathe. My lathe is not terribly heavy so I don't think it will distort the concrete floor. It is not bolted down. Just sittin' there. First I levelled the bench and then the lathe on the bench. I used a starret precision level to do the job. Takes a bit of getting used to the bubble shooting to the end with a slight adsutment. Not your average carpenter's level. When I first got the level I put it on the counter. When I leaned over to look at it I had my hand on the counter for support and that weight of me leaning on the counter sent the bubbble right to the end!. Amazing! DW, I'd love some info on setting the level to level, (if that makes sense). Have a great weekend.
Al
 
Setting "levels to level" is surprisingly easy. You just rotate 180 degrees on the same surface and keep splitting the difference in between adjustments.

I never thought a machinist's level would come into use often -until I bought one. They make other levels look like 3rd order magnitude approximations...



Allan said:
Thanks DW and Jim.
Stability is why I had a steel frame bench made up rather than use the wooden on that came with the lathe. My lathe is not terribly heavy so I don't think it will distort the concrete floor. It is not bolted down. Just sittin' there. First I levelled the bench and then the lathe on the bench. I used a starret precision level to do the job. Takes a bit of getting used to the bubble shooting to the end with a slight adsutment. Not your average carpenter's level. When I first got the level I put it on the counter. When I leaned over to look at it I had my hand on the counter for support and that weight of me leaning on the counter sent the bubbble right to the end!. Amazing! DW, I'd love some info on setting the level to level, (if that makes sense). Have a great weekend.
Al
Click to expand...
 
Let me make a comment here: If you get your lathe bed perfectly level at the front and rear,and it cuts a taper,like someone mentions above. It is because THE TAILSTOCK is offset. You should NEVER twist your lathe to make it cut true. Get the bed level,and adjust the tailstock sideways to get it to cut a true cylinder. Do not just leave the bed with a twist in it. This can result in the lathe bed getting a permanent twist. All decent engine lathes have tailstocks that can be set sideways,ostensibly to turn tapers. Don't forget that your tailstock may not be set perfectly if your perfectly leveled lathe cuts a taper.
 
Hello All, this topic has created great information from all of you, and this is something dear to all of our hearts. My father and law and I had this very discussion just a few weeks back and I learned a great deal. See this page taken from Southbends Leveling Manual. I always thought the tailstock played a big role in the undesired tapers, but the leveling test described here does not use the tailstock. Of course after adjusting via the test bar, then the fine tuning of tailstock adjustment. My 13" SB has a 6 foot bed and always presented a problem of tapering until I did this test, adjusted it by placing .o55" shim under the back leg of lathe at tailstock end. Then aligned the tailstock. The bed doesn't indicate as level as before but the lathe sure cuts better. This may not help with the shorter lathes but great topic.Thanks for letting me put in a half cents worth. RWW
 

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Thanks, RW.
That is the approach I was thinking of- shimming under the tail stock to put it back to zero- zero. I cut a nice bar from a McPherson strut from a car. Looks to be good steel- nicly polished. Haven't tried turning it yet. Some struts use larger rods than others. Most repair shops will have many cast-offs available for cheap maybe even free. I guess I will have to mike it and see if it has worn over its range of travel. Although, the test calls for it to be turned anyway so it probably doesn't matter.

As a safety note: before cutting the can open make sure that the gases are released from inside. Most are and that is why they are being replaced. If the rod feels "bouncy" at the compressed end of the stroke you may want to drill or cut a small hole to let the gas release. Wear eye protection.

Al
 
Hi, George.
I want to get the bed levelled first. My lathe apears to have a small permanent twist already. I will try a trial cut to see if the .002" makes any difference. Do you have a technique for lining up the tailstock to put it on center?

al
 
Thanks, Ray.
That's basically what I di with mine. Put it on the ways and turned and adjusted.

Al
 
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