935 floor base

[szenieh]

Of course it is. But I have the right to compliment him on a very well executed design.

Perhaps they are, perhaps not. But my point about isolating forces remains valid. In Engineering, you are taught to recognize all forces, what is in tension and what is in torsion. No need for FEA to do this.

- You may build things any way you choose. I'm pretty sure I'd like your design also.

David moves his machine with a narrow pallet jack. I intend to move my machine with the caster-level. As one moves the machine, a wheel may encounter an obstruction of some sort that will introduce a lateral force on the angle iron and, more significantly, a torsional moment tending to twist it out of position. I am using 3"x4" 3/8" thickness that has to become an integral part of the base. The only reaction forces and moments to such a perturbation, are provided by the all-thread that ties the angle iron to the base and the friction/vertical wall between the angle iron and the base.

The 5/8" all-thread is stout and has a "clamped" end conditions both at the top of the base and at the connection to the angle iron. The applied torsional moment will tend to bend that all-thread. The friction between the angle iron and the bottom of the base will counter-act the force introduced by this "bump" as well as the vertical wall resting against the angle iron (this reaction is dependant on the direction of the perturbation). My concern is mainly the torsion- it will tend to bend the 10"-all-thread, or at the very least, introduce stresses on the 5/8"-11 nuts' connection that will tend to losen them.

As Dabbler said, there are potential torsional torques that one will see only because I am designing for moving the machine. For David, he does not have that problem, as he picks up the machine and moves it with a pallet jack.

I have prepared a 1/4-model in solidworks to run some FEA simulation (as Dabbler said, a simple engineering static analysis will suffice, but why not go all out and run a simulation). I suspect that for low enough obstruction force (bump on the wheels), the tie rods may not be needed. But they do provide a mitigation to counter-act that torsional moment should it arise. That was the reason why I added the tie rods. Notice that the entire assembly becomes a torsional box that is a lot more stable with these tie rods. Below may help illustrate the perturbation and the reaction moment I am stipulating.

Once I run the simulation with few loading conditions, I will post the results.

 

[PFC Lug Nut]

Here is the base I built for my 935 TV, very simple. FootMaster GDH3 casters, raises the mill 6 inches.
The mill on the base rolls around so easily, I was shocked.

 

[websocket]

I went with leveling casters too, https://www.zambus.com/products/alc-1000fb.html. The mill is level so the casters rotates freely as shown between the two images.

 

[PFC Lug Nut]

II went with leveling casters too, https://www.zambus.com/products/alc-1000fb.html. The mill is level so the casters rotates freely as shown between the two images.

Simplicity, I like it. I would have used angle if I had it on hand, does not raise the mill as much. Nice. The casters you used are rated higher, and cost less than the casters I used.

 

[verbotenwhisky]

I bought the yellow pads from PM when I bought my PM940V, they worked very well on my garage floor. I did the say for my Lathe but had to use a thick chunk(s) of aluminum to get level, it worked out well also. I have no intentions of moving either of them around, the mill is around 1300Lbs and the lathe is bumping 1200Lbs, for me it isn't like moving a couch around the living room, I carefully placed them in pre-planned thought out locations to avoid re-leveling and all the other issues that go with it.

 

[ClayPort]

Hi all. I just picked up a new to me 2018ish PM935TS. My mounting holes are 3/4" threaded but the thread only goes about 1" deep, which is about 1/8" shy of being able to punch all the way through. My plan is to mount the machine to a mobile base and am curious if anyone finished tapping their base with a 3/4x10" tap or if they went with 5/8" all-thread like David did. Thanks.

 

[davidpbest]

David moves his machine with a narrow pallet jack. I intend to move my machine with the caster-level. As one moves the machine, a wheel may encounter an obstruction of some sort that will introduce a lateral force on the angle iron and, more significantly, a torsional moment tending to twist it out of position. I am using 3"x4" 3/8" thickness that has to become an integral part of the base. The only reaction forces and moments to such a perturbation, are provided by the all-thread that ties the angle iron to the base and the friction/vertical wall between the angle iron and the base.

The 5/8" all-thread is stout and has a "clamped" end conditions both at the top of the base and at the connection to the angle iron. The applied torsional moment will tend to bend that all-thread. The friction between the angle iron and the bottom of the base will counter-act the force introduced by this "bump" as well as the vertical wall resting against the angle iron (this reaction is dependant on the direction of the perturbation). My concern is mainly the torsion- it will tend to bend the 10"-all-thread, or at the very least, introduce stresses on the 5/8"-11 nuts' connection that will tend to losen them.

As Dabbler said, there are potential torsional torques that one will see only because I am designing for moving the machine. For David, he does not have that problem, as he picks up the machine and moves it with a pallet jack.

I have prepared a 1/4-model in solidworks to run some FEA simulation (as Dabbler said, a simple engineering static analysis will suffice, but why not go all out and run a simulation). I suspect that for low enough obstruction force (bump on the wheels), the tie rods may not be needed. But they do provide a mitigation to counter-act that torsional moment should it arise. That was the reason why I added the tie rods. Notice that the entire assembly becomes a torsional box that is a lot more stable with these tie rods. Below may help illustrate the perturbation and the reaction moment I am stipulating.


View attachment 406120

Once I run the simulation with few loading conditions, I will post the results.

Did you post the results of the FEA and I missed it?

 

[Dabbler]

@szenieh I have some machinery skates of Oxtool's design, using ready rod torsion members, and they work great. No reason not to add them!

I'm currently working on the design of some machine skates that are fully steerable, and handle 5,000 lbs each. Winter project, here we come! The normal Hillman type rollers aren't steerable - you have to lift up each corner of the machine when you change direction. My goal is to make them track the lathe or mill by attaching them to the machine, eliminating the problem where one skate gets left behind in a depression. It happens too often!