View Full Version : CNC router deflection calcs and cutting loads?

09-10-2004, 09:58 AM
Hello all ..

Just wondering if there are people in the CNC community who have real world ideas of what kind of loads are placed on the cutting tips for general wood routing.

I'll explain : I have been designing a CNC wood router for MDF products using an aluminium profile of my own design. (I have negotiated with a local aluminium extrusion company to create a structural profile that can also be used as a linear guide rail)

For the Y axis gantry (Moving) I have boxed 4 extrusions to create quite a strong beam and am now trying to decide what my limitations are as far the maximum size for Y.

Using a spreadsheet and some dusty equations from my Mech eng backround I have formulated the following figures:

With a beam length of 2m and a point load of 50N in the centre of the beam I have a max theoretical deflection of 0.5mm in the x-x direction.

2(or more) questions arise :
1: is 0.5mm deflection a real problem in terms of cutting interlocking MDF furniture parts ? What is the exact effect of the deflection during the cutting process? How does deflection affect cutting perfect circles?

2: is 50N a relatively real world figure for cutting load or should I factor in more of a load?

If anyone has any comments I would most appreciate your feedback..


Paul (Linus) Low

09-10-2004, 11:08 AM
The deflection will be related to the power of your spindle, the feed speeds your running at and how sharp your tooling is.

When you say interlocking, are you talking about sliding parts in slots, or dadoes? Could you clarify this a little?