X-axis cut accuracy

I have been carving 4 inch diameter coasters using 3/8 inch birch multiply. I have been using a 60 degree v-bit to detail 5 or 6 downloaded images on the surface and a 1/8 inch spiral bit to cut out the disk. To be consistent I was running the surface grain parallel to the y-axis and was unhappy with tear out and poorly defined lines. Observation showed the bit deflecting at the end of x-axis movements and the entire router was tipping slightly in either x-axis direction. It is apparent that this happens because the router mounting plate feed screw is in the centre while the guide rails are about 2-1/2 inches to either side. My solution is to run the workpiece grain parallel to the x-axis which creates less resistance to the cutter along the x-axis. The stability of the router when cutting in y-axis direction seems to overcome the extra resistance of the cross grain cut. Can anyone suggest a better solution?

@ADB8056 Bit deflection when using 1/8" bits can only be reduced (I don’t know if it can be eliminated entirely.) by conservative feed rates and depth of cut rates. Plywood can be a bear since the glue between plies wants to grab the bit.

As for the router moving, that would indicate that something is loose. I would suggest that either your v wheels are not snug enough or your router mount is loose.

Finally, raise your router as high in the clamp as you can. Clearly, you still need enough Z travel to allow the bit to touch the spoil board. However, raising the router reduces the amount of leverage exerted on the Z gantry by the bit working in the wood. Some of us saw this as helpful when we were routing aluminum and needed all the rigidity that we could get.

Thanks for your prompt reply gwilki. I have gone over the router mount plate and everything is tight. I was able to raise the router about half an inch in its clamp bracket. I also reduced the pass cutting depth to 0.025” as the total is 0.045”.
If I hold the router spindle nut between my thumb and finger I can easily push and pull along the x-axis to deflect the the bit tip about 1/16”. I observe the router mount hinging about the bottom of the z-axis feed screw while the sides move up and down on their rails.
I observed this same principle years ago when a friend and I compared a thickness planer that was adjusted with one screw in the centre to a planer adjusted by a screw on each side. The one with the centre screw would not keep the table parallel to the knives unless we fed wood of equal thickness in simultaneously on each side.
One of the main reasons for the new x-axis and y-axis gantries in the MK2 seems to be for more rigidity and cutting accuracy. In my opinion that won’t mean much if the z-axis isn’t improved too.
Don’t get me wrong - I am having fun and learning every day. I just want the most accuracy possible.

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@ADB8056 I can’t move the router in any direction at all. I certainly could not live with a 1/16" movement. I’m a little lost when you mention “hinging”, Donald. It would likely be worth your while to open a ticket with Sienci. My limit is pretty much advising to look at the v-wheel adjustment and the anti-backlash nut adjustment in situations like yours. Not much help, I know.

Thanks gwilki, there is no movement in either the v-wheels nor the backlash nut. By hinging I mean that the mounting plate doesn’t move up or down in the centre under the feed screw but one edge moves up on its rail while the other moves down and then visa-versa when pressure is applied in the other direction. A few seconds of video would make it very clear. I will try a ticket with Sienci. I am very happy to hear that this isn’t normal!

Problem solved! The four little bolts that hold each side of the router mounting plate to their respective slide bars were loose enough to allow movement. Because that part came assembled and the guide bars weren’t easy to see I didn’t check them. Now I will be checking every bolt on the machine! It now takes a lot of force to deflect the bit tip 1/64 of an inch. That is very acceptable and I can’t wait to try it out tomorrow as the solution came to me as I was trying to fall asleep.

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@ADB8056 Glad to hear it Donald. Have fun.

As the original issue has been addressed, I’m closing this topic. If anyone else has a similar concern, feel free to start a new topic, which will ensure that it is addressed promptly.

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