PM1236 leveling feet question

[mcoak]

I am in the process of setting up my new PM1236 lathe.

There are eight locations to attach leveling feet - four on each stand. Should I install eight leveling feet?

Also, I read a post here about getting the headstock end of the lathe level before leveling the bed. Where in the headstock area is a good area to set my level?

Thanks,
Mitch

 

[T Bredehoft]

I'd put the level across the ways, blocking it up on 1 2 3 blocks or some such, right up against the headstock, under the spindle. (or as near as you can).
Unless you're working for NASA, level the right end and check for taper with a test bar. Once it's level, and the test bar checks out, let it go, don't obsess about it.

 

[Muskt]

Hello Mitch. Jerry here--WV transplant now living in Delaware after 30+ years in Alaska.

I also have a 1236. I built a stand/support base to raise the lathe a few inches. I only used 4 feet/levelers under it. I cannot say that that is sufficient of not; but, it appears to work OK. Here is a link to a (pretty long) thread about my new shop (couple of years ago).

http://www.hobby-machinist.com/threads/my-new-shop.34249/

If you scan through all of it, you will see pics of the leveling feet that I used and where I obtained them. On the second page of the post, is a pic of the base I created showing the feet in position. I think that attempting to "level" a machine with 8 feet would be somewhat similar to changing a tire while doing 50MPH. But I digress.

Several years ago, I owned a Grizz 9x20. There was lots of discussions on the forum about "leveling". I became involved.

The following is a post I made concerning "leveling" the 9x20. I used the same procedures/techniques on my 1236. It wasn't nearly as bad as the 9x20 was.
I'll post the entire thing here, and you may (or may not) derive some benefit from it.

Here goes.
Jerry in Delaware.

Since there are several new members to the group, I am re-posting a blurb on "leveling" that I initially posted in April of 09. I do not claim that it is a definitive "how to", only a description of how I went about it.

Before I go any farther, I need to clarify one important point. The term "leveling" is generally meant to mean to check the bed of the lathe for parallelism (meaning that it is straight & not twisted). Being level really has little meaning for a lathe, other than being a starting point for the check.

The following is my earlier post:

"All the discussions about "leveling" has gotten me to thinking about my machine.

I have a Starrett 98-6 level. It is advertised to give accuracy of 0.005 inches over 1 foot per gradation.

I went out to the garage/shop & removed the plinth from my cross slide.

I cleaned it (the cross slide) well and placed the level in the center (perpendicular to the ways) and moved the carriage till the level was just under the chuck jaws.

Next, I shimmed the far end till the level read "zero".

I marked the near way and then moved the carriage 18 inches toward the tail stock end (I had removed the tail stock.).

I read the level, & it showed that the far side way had risen two & one half (2 1/2 ) gradations. At 0.005 inches per grad, I determined that the bed was twisted approximately 0.0125 inches over the 18 inches of travel.

Not good, I think. Twelve & a half thous is a lot. Time to do some thinking.

So far, I just have a number that looks large to me.

How that number translates into real live turning is the important thing to me, not just the number.

Here are my thoughts & reasoning behind my conclusion (which I haven't revealed yet).

This is a bit convoluted, so bear with me.

I know that my bed is twisted, so how can I determine the effect on turning (leave the HS alignment completely out of the equation for now).
I must know the amount that the cutter moves into or away from the work, not how much the bed is twisted. I can calculate that amount by determining the height of the cutter from the cross slide (the point that the measurement was taken from). I placed a dead center in the chuck and measured the height from the cross slide to the center of the dead center and determined it to be 3.687 inches. Now I construct a right triangle (mathematically--not a real triangle) with a base leg of 12 inches and a vertical leg of 3.687 inches. If I set the triangle on the cross slide with the 90 degree angle exactly below the center of the spindle axis and the base leg on the cross slide pointing away from me and then raise the far end of the triangle 0.0125 inches, the point that is under the spindle center will move toward me.

HOW MUCH?

I set up a proportion equation and arrived at 0.00384 inches. WOW, that is quite a bit. OK, so I didn't account for radial movement of the theoretical points. I will just accept that the curve of the very small arc will be a straight line--so if anyone wants to argue about that --- DON'T.

Continuing on.

Remember, though, that that number (0.00384) isn't arrived at at the spindle, it is 18 inches toward the TS.

Here is my conclusion.

If I divide the 0.00384 deviation by the 18 inches , I arrive at 0.00021 per inch of deviation due to bed twist. That is not nearly so terrible as I had initially thought.

The story continues......

When I made the measurements, last evening, I had been at the lathe for at least 30-45 minutes with my "work lights" on. My lights are 2 150 watt halogens that shine on the lathe from above and to the rear. I know they put out a lot of heat. I live in Alaska, & my garage/shop normally (in the winter)(yes, it is winter here) remains at around 50 degrees F.

I went out this morning and quickly tried it again (I had left the level & shims in place when I quit for the evening).
The level still showed "zero" at the chuck end, but only 2 grads high on the TS end. Wow, that is a 20% difference just due to the possible effects of the lights warming the lathe unevenly.

My lathe is not bolted on the TS end, it just sits on a riser with a bolt acting as a pin to prevent sliding.

I really don't know where I was going with this entire exercise, I just felt like doing something.

The next project will be to check/adjust the HS alignment, again (I haven't checked if for a couple of years)."

Jerry in Anchorage

 

[jjtgrinder]

This is what i did and it worked great:

http://www.hobby-machinist.com/threads/g4003g-bedding-the-lathe-to-the-floor.49913/#post-425131

My G4003G is dead accurate (after some fine tuning).
Others will say it's "overkill", but you cannot argue with success.
I used four "feet" under the head-end and two "feet" under the tail-end. This enables the
leveling process to work easily.
Take a look a the photos in my album.

If you have questions let me know.

 

[jjtgrinder]

Where in the headstock area is a good area to set my level?

Level the lathe "end-to-end" lengthwise first (unless your setting up shop on a boat). Then as "T Bredehoft" said, put the level under the chuck across the ways.
The important thing is to be able to keep the relationship of the ways consistently level as you move from head to tail end. No twist.

 

[mcoak]

jjtgrinder, Tom, Jerry thanks for the information! The machinist level just arrived. I'll let you know how it goes.

Mitch

 

[badiozam]

I didn't want to drill holes in my garage floor, so I made 1018 steel leveling feet.

Here's my design (I used FreeCAD for a real basic "back of the napkin" draft). The holes are tapped 1/2" - 13 and I used some steel 2.5" - 3" bolts and 2 matching nuts per bolt. I screwed bolts all the way through the bottom (with a washer for good measure). Then I use two nuts per bolt, one below and one above the stand to adjust each foot accordingly using a machinists level.