Countersinking enlarges hole

[usapaul]

When I countersink the holes in the y-car carrier plate (10 30 450) it enlarges the hole before I can get the screw flush. I have only completed 1 hole like this on the motor side. It looks to be the hole that would be used for a lite spring setting. I am using an 82 degree cutter as that was all that was available and it looked close. Is this going to cause a problem? Is it necessary to cut all the way until the screw is flush?

[smreish]

Paul,
I found that I split the difference. My machine screws are not completely flush, but sunk enough to stay clear of the rails. Does that help?
Sean

[usapaul]

I think I will countersink to a point where it is not yet enlarging the hole and then go deeper if necessary once I get the rails and wheels fit. It doesn't seem like an enlarged hole will cause a problem.

[gmessler]

Paul,

You shouldn't have to countersink the hole for the spring tensioner. Only the second motor hole opposite the pivot.

[Gerald D]

The depth of the countersink is not critical. Suggest you drill until just before it enlarges the pilot hole. The screw head will be proud, but should not touch the rail. If it does foul the rail, then grind the screw head down a bit.

[Gerald D]

Remember that this countersinking is for the Gantry ends as well as for the Y-car.