Pm 1228-vf-lb Lathe Preparations

[Franko]

Ok, today is the big day. Chuck the welder came over this afternoon to give me an extra hand lifting my lathe on the stand. It all went very smoothly with no hitches. We were able to do with the engine hoist.

I got a couple pieces of 1/4" cold roll steel to put under the feet of the lathe. I was going to imbed them in the wood top, but decided to just put them under the feet above the chip pan. I painted them to discourage rust.

Ok, here are the money shots. I'll be wiping grease off it for several days.
I'll put the back splash on after I think I've gotten most of the shipping oil off.

 

[DoogieB]

Wow, the lathe is bigger than I thought it would be! I have one of those 44" Red Roller toolboxes so that's a good size reference for me.

Maybe you can tuck-in one of the side cabinets on the left side? You can never have enough storage space.

 

[Franko]

Yeah, Doogie, that is not a small tool box. The overhang on the ends is more than I originally planned for when I ordered the PM1127. Even though this is a 28" lathe, I think it is 5-6" longer. Everything is very sturdy and the lathe stand is solid.

I made some chips on it this evening. It works great. I haven't leveled anything yet. I did check the ways with my new Starrett level. It looks like there is about two lines difference between the chuck and the tailstock. I'm not how much twist that is. The Starrett is supposed to be accurate to .005 per 12 inches. I guess each line is equal to .005. Maybe the twist I'm seeing comes to .005, since the ways are 6.5" apart.

But, the lathe is considerably higher than I would prefer. I've done all I can to lower it. The cross slide handle is about 3" above my elbow. It isn't uncomfortable, but it feels much different than my old Grizzly. I guess I'll either get used to it or make me a platform to stand on in front of the lathe. I can see the top of the tools without tip-toeing.

I am disappointed with one big thing. The cross slide is too high for an AXA QCTP. With the bottom of the tool holders all the way down on the compound slide, a 1/2" cutter is about a twentieth of an inch above center.

I regret selling the AXA QCTP with my Grizzly. I had the tool holders ground down about 40 thousandths so they would work. It was very expensive and I'll not do that again.

I wonder if the tool holders for indexed tools are hardened? If not, I could mill a few thousandths off of them so they'd be the right height. I doubt 40 thousandths would weaken a 1/2" tool enough to notice. If they were hardened, the set screws wouldn't mark them, would they?

I guess there is one way to find out. Clamp one up in the mill and see what happens.

 

[Muskt]

That setup looks really nice, Franko---Congrats.
As a previous 9x20 owner also, I faced a similar situation to that which you now have, namely bed twist. I wrote a treatise on the Yahoo 9x20 forum several years ago concerning how I measured the twist. I never claimed that it is correct; however, it may give you an idea or two as to how to start determining how much your machine is twisted. I'll enclose the whole blurb below, and hope you find something of value in it.

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 carraige 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.

So, to you the members, the practical machinists, the theoretical machinists, and the home shop tinkerers, have at it. What did I do that is wrong/stupid/incorrect? I can handle the criticism without getting upset.

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"

 

[Franko]

Thanks for the thoughtful post, Jerry.

I hadn't thought of putting the level on the cross slide. That makes a lot of sense. I'm not sure how the top of the bevels on the cross slide are crucial measuring points.

The only reason I put the level on the lathe yesterday was because I have a new level and just wanted to see what it said. At this early juncture, there isn't any point in trying to zero the relationship of the ways.

The bench top is plywood. I glued it up as flat as I could, but I'm sure there is some twist and warp in it. For that matter, there was no way to determine how square and true the tool box is. My guess (and it is only a guess) is that it is all going to settle into a fairly stable state after a few days or weeks.

There is also some adjustment and manipulation as to exactly where the lathe and stand is going to live in my shop. Some things are having to get moved around and rearranged to accommodate the much bigger machine. So, at this point, I haven't even made any effort to level the stand, much less adjust the ways.

 

[MSD0]

Looks really nice Franco. Bummer about the tool post, but I bet the tool holders could be machined down.

 

[jbolt]

I am disappointed with one big thing. The cross slide is too high for an AXA QCTP. With the bottom of the tool holders all the way down on the compound slide, a 1/2" cutter is about a twentieth of an inch above center.

We had the same problem with our 1127LB. The crazy part was that it came with the QCTP that would never work as delivered. PM's solution was to send us instructions on how to modify the compound slide base. Fortunately I have a mill and could do the modifications but what if a customer didn't have a mill or access to one? Not cool.

I am over all pleased with the PM products but these kind of issues need to be address before new machines are ready to release to customers.

You might be able to modify the compound base vs. machining a bunch of tool holders.

Good luck!

Jay

 

[Franko]

Thanks, MSDO, Jay.

Nothing I had would machine the tool holders. They are very hard.
My sharpest carbide end mill just made feathered sparks. All I was able to do was polish them.
I had to have them surface ground down for the Grizzly, at a hefty price.
I don't plan to have that done again at $40 each.

I'll try to shave some off the stems of the insert tools I have. I don't think they are hardened.

Here is a shot for scale.
(ignore the man behind the blue curtain)

 

[wrmiller]

Franko,

After looking at that compound design for a fair amount of time, I would take about .100" off the bottom of that massive block that the compound sits on. It has twice as much material than either of the compound pieces have so it is certainly not the weak link in the system that's for sure.

Just an idea...

 

[Franko]

Funny you should say so, Bill.

Matt just replied to my email about it and said they are modifying that very part and a replacement will be sent to us fairly soon. (who knows what that means)
He said that was in the design specs and the factory failed to do it.

He offered to mill mine down if I didn't have a mill and am in a big hurry. I can live with using 3/8 tools for a while. That's as good service as I can expect.

If I get in the mood and feel like doing it, it should be a very easy modification.

If I just have to use the 1/2 tools, there is always the 4-way that is very easy to switch.

For the time being, I think I've found a good spot for the lathe. I put a level on the wheels and made some adjustments to bring the stand to pretty close to perfect level. I had to replace the thick washer I made to space down the leveling casters. I found some 1" hole washers and shimmed the holes in two of them on each caster with flattened out 5/8" lock washers, which lowered the right side about 1/4".

It is all level now and the feet are cranked down to the floor. The stand is rock solid. It doesn't wiggle a bit no matter how hard I try to shake it.

I checked the ways with my machinist level and they are off about two marks on the vial. I'm not going to try to shim them straight until the plywood bench top has a week or two to settle. It should flatten out pretty good with 500 pounds pressing down on it.