Pat,

I did some prelim assumptive figger'n and this is what I came up with.

NB: all math done in SI units and converted back to Imperial

Load 1000 lbs (knee) No work piece mass included

screw 1.5" x 5 tpi

wheel 14.4 " diameter

mill is horizontal, zero degrees incline, therefore no part of the knee's

mass has to be lifted.

Force needed is inertial+frictional+acceleration

Assume loads is carried by rolling steel wheels on top of steel plate

so COF = 0.002.

If sliding steel on lubed steel, COF goes up to 0.16 a whopping 80 times more.

**Result:**

**An operator force of 2.2 lbs on the wheel will generate**

**a knee movement of 0.25" in 1.8 seconds.**

I would CERTAINLY hope some one else does the math to

check my work.

If you incline the knee/table, you have to lift some of the knee's mass

so the effort goes up.

So, what's the benefit of the tilted knee vs flat?

lance

++++

On Sep 2, 2010, at 2:36 PM, Pat wrote:

In the "1 Concrete Mill" photo folder I put a concept drawing of a new type of concrete milling machine. The "knee" could weigh at least a thousand pounds (like real mills). The angle of the incline, the lead screw thread and the handwheel size will have to be figured out by someone smarter than me.