Setting-up the PM 1236-T Lathe

[Jester966]

I wanted a system that would allow me to move the lathe without needing to spend a bunch of time re-adjusting it.

I agree this system would certainly make it much quicker to drop the lathe onto wheels to move it around. But, wouldn't you still have to re-level the lathe every time you park it?

 

[Titanium Knurler]

Quick correction: outriggers are 3/4" thick not 1/2" as stated above.
Sorry about that, TK

 

[Titanium Knurler]

Jester966. great question. As John.k mentioned in the second post of this thread, "A lathe does not need to be level in any axis............it makes no difference to the accuracy..................however being level means an accurate level measurement tool can then be used to check for bending or twisting of the bed,and such corrected .......and later on used to check for wear..... "

What I do after I have moved the lathe is quickly level it with the leveling feet on the casters and the three spirit levels(one at the front, two at the side) that are on the underside of the plate supporting the lathe(more on this later). I look up at the levels while I am adjusting the leveling feet on the casters. I have adjusted them so they agree with the Starrett 199Z precision level. That is all I do now that I know that movement is not affecting the lathe. This takes just a few minutes with the wrench on the casters but even this amount of leveling is not necessary.

 

[Titanium Knurler]

Jester966, think of it this way. Say you are a machinist on a battle ship, your captain runs aground in choppy seas and bends the prop shaft. The enemy is approaching and you need to turn a new prop shaft pronto! Your lathe was adjusted on land to have no twist in the ways and then bolted to the battle ship. But now you are at sea, the ship is pitching and rolling! What do you do? You turn a perfectly untapered shaft because the movement of the ship, even though it is creating a constantly unlevel lathe, has no affect on your lathe as long as the ways are untwisted. You are promoted, retire with a huge pension and live happily ever after. Think of the plate on the mobile base as the battle ship.

 

[Titanium Knurler]

2.) Machine Mounts



The PM stands is made of two very substantial vertical columns made of 3/16” steel plate and a heavyweight 16 gauge connecting panel that attaches to the columns by way of several small screws to a piece of angle iron welded to the side of each column.

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The components are all heavy duty but when they are bolted together there is a fair amount of movement of the columns especially in the vertical axis. In fact, when I was trying to carefully mark the positions of the mounting holes for the lathe on the top of the assembled cabinet I had to use a bar clamp, with the ends reversed, to counter the toe-in of the columns. I imagine when the cabinet is used as intended, as a stationary base with the lathe bolted directly to it, the stand is plenty rigid, however, I don’t think it is rigid enough to be used as a mobile base without a baseplate. Something more rigid, such as a cast iron base, might provide the rigidity needed for a mobile base without modification.

Because of the movement of the stand I used a baseplate to provide a stable mount for the lathe. The equipment mounts help mitigate the effects the movement of the stand on the plate; when the stand flexes and twists the rubber mounts will absorb this force.



The above is a labeled mock-up view of a mount, it’s hardware and the relative positions of the cabinet top, baseplate and chip tray. If you envision that this is just one corner of the mobile stand I think you can visualize how the mounts help reduce the forces of a moving stand on the baseplate. If while moving the stand a corner drops, say it passes over a drain in the floor, the lower pad will compress and the upper pad will expand until the ability of the pads to compress or expand is exceeded then the force will be applied to the baseplate. It is like you have a spring above and below to absorb the forces. I doubt this arrangement eliminates all forces on the baseplate from a moving and twisting stand but I do think it minimizes them and is better than mounting the baseplate directly to a shifting stand. This elevated arrangement also allowed me to easily access the jack screws for leveling that are on the tailstock end of the baseplate and to place a drawer under the baseplate. You might be asking yourself if this elevated arrangement may cause increased vibration of the lathe? I will answer this question later with some vibration measurements once the lathe is attached to the stand.

To use the equipment mounts I had to enlarge the small oval holes to on the top of the stand to 1-1/4” so they would accept the equipment mounts. If any of you have ever tried to use a hole saw to enlarge an existing hole that is larger than the pilot bit you know it can be tricky. I clamped a board on the backside and used the drill press; this seemed to do the trick.

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This view shows the mounts in place ready for the hardware:



I used eight inch 1/2”-13, 316 stainless bolts and oversized locknuts And heavy duty fender washers:

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Here is a mount that has been installed:



This last view show the stand columns leveled and the mounts installed and ready to accept the baseplate, chip tray and finally the lathe:



Well, that’s it for the equipment mounts. Now on to the last component of the mobile stand, the baseplate.

 

[Titanium Knurler]

3.) The Baseplate



Of course the baseplate is the key element in creating a mobile base that will provide the stability needed to maintain the lathe adjustments. I used an 18”x75”x1/2” A36 steel plate. I drew a sketch, had a CAD drawing made and sent this to a company called Precision Grinding, inc.(PGI) in Alabama. You have to love a company whose logo is, “ We Grind”. Their website is precisiongrinding.com, the phone number is 888 934-7463. Ask for Jerry(jerry@precisiongrinding.com). I asked them to hang onto the CAD drawing in case someone from HM wanted to use it. They plasma cut, stress relieved and ground the plate. It took about six weeks. If you would like to have a plate made locally and want a copy of the file let me know I will try to get it to you somehow. I have it in PDF, DXY, DWG, SLDPRT and SLDDRW. I want to emphasize that I do not think you need a plate that has been stress relieved and ground. It is overkill. All that is needed is a good stable plate. It does not even need to be perfectly flat, just substantial and stable enough to allow you to adjust the lathe with jack screws or shims and maintain that adjustment.

Below is a screenshot of the PDF for the plate:



This shot shows the underside of the plate:



I will just briefly describe some of the things you may be wondering about on the plate and show you a few photos. The oval windows are just handles to move the machine around. The round cut-out is for the Drain in the chip tray. There are six oversized holes for the lathe mounting screws to pass through. I oversized these to give me some leeway and just in case there is a difference in the thermal expansion of the steel and the cast iron of the lathe. There are three spirit levels attached that I can watch while leveling the plate with the leveling feet. This really makes it quick and easy to do this job even though, as I mentioned above, this is not something that must be done for lathe accuracy. There are four 1/2”-20 threaded holes on the tailstock end for jack screws. I used screws for the Starrett mini equipment jack here. I have four, you only need two. Finally, there are four screws to attach the drawer.

Let me show you some pictures:

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Here is the stand with the chip tray ready for the lathe:





Well, that’s Pretty much it for the mobile base, just three components: outriggers/casters, equipment mounts and baseplate. It may look strange but it works. Next is mounting and leveling the lathe.

 

[mikey]

I am not understanding something - what is the purpose of the jack screws? They are pointing down with nothing under them so I'm confused.

I find it interesting that you have sought to isolate the lathe from the ground via the mounting plate and rubber isolation pads. Most set ups seek to make the connection to the ground as solid as possible to enhance rigidity. Can you expand on your thinking here? Not a criticism; mostly just curious.

 

[Titanium Knurler]

II. B. Mounting/Leveling



The stand is now ready to drop the lathe on it but there were a couple of things I wanted to do before I did. The first thing is that the cast iron enclosure on the headstock that holds the motor control switch was very close to the mounting bolt and made it very difficult to get to the nut for the mounting bolt so I removed the box and milled out an area to accommodate the nut:



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The second thing I wanted to do was to seal the base of the lathe to the chip tray. The PM manual suggests using silicone but I was planning on using Hangsterfer’s CC22 cutting OIL as a coolant and silicone does not hold up well with oil. I contacted 3M and they suggested Scotch-Weld Acrylic DP810 NS adhesive for oil and cast iron. So I lowered the lathe temporarily onto the stand, outlined the area of the lathe then roughed it up with sandpaper. I then applied a liberal amount of adhesive and lowered the lathe onto it:

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When I tightened the nuts on the nuts on the mounting bolts they demanded to bend because the lathe base is angled so I made some angled spacers to eliminate this:

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So there you have it, the lathe is now ready for leveling!



By the way, has anyone guessed what the vertical red thing is on the front panel? A prize for whoever guesses correctly.

 

[mikey]

Nicely done.

The red thing? Easy. Its the indicator for the built in Kool Aid dispenser's reservoir. Or the coolant tank, maybe?

 

[P. Waller]

So there you have it, the lathe is now ready for leveling!

I suspect that this will be wildly entertaining, I am 60 years old so will likely not live long enough to see the end of this "installation".


Good Luck