Simple Pocket Not Smooth

(John Ellenberger) #1

Very simple test Create project–text in a box. One pocket path using the 102 1/4 straight end mill.

Rather than a nice smooth bottom I get a bunch of little pock marks. At least with the 101 I got these uniform ridges on the bottom. 1/4" popular held down with the mounting tape.

Is there something I am doing wrong in setup?

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(Daniel Loughmiller) #2

I got something similar once when I didn’t have the collet fully tightened, caused the bit to move around and was, unbeknownst to me, super dangerous.

(John Ellenberger) #3

In this case the collet (the Carbide 1/4 collet) was very tight. I watched it actually cut those pockmarks. Its like I am not getting a consistent Z depth. Some parts of the path get machined deeper than others. And they are not in a consistent area so I don’t think its the table or the mounting.

(Daniel Loughmiller) #4

Is this a recent assembly? The set screws are notoriously prone to being loose from the factory. Each motor pulley has two screw holes, very small with small black screws inside. One of those screws needs to be tight against the flat of the motor. One easy way I use to check if they’re set is to turn the machine on so the motors ‘lock’ then see if the z-axis plate slides at all when pressure it applied, you’d actually be able to see the pulley move slightly if that were the case. The other motors can be checked similarly but start with Z since that’s where your issue is.

(Curious in Portland) #6

I noticed that I too had some roughness on my pocket bottoms.

I noticed there was a bit of play on the Z and Y axis and tightened up the v-wheels. That seemed to reduce the roughness considerably.

(John Ellenberger) #7

Thanks for the suggestions. Will check into them. Seems like adjustment is a never-ending struggle.

(Jerry Gray) #8

When my machine was new, it seemed the belts had a little breaking in (stretching) to do.
Z down low was inconsistent, like yours.
You only want the v wheels just snug enough, that it stops turning with finger pressure.
I also took off one of my springs. It had a hard time pulling both springs far enough to reach the spoil board.
After a few times, and z belt not being really loose, it should line out.
Temps also had slight effect. Starting off cold, it will stretch, just a little after a couple minutes.
After the “break in” it runs consistent, now.

(John Gowrie) #9

John, how did you make out with eliminating or reducing the sloppy bottom finish? I have the same thing going on with my machine.

(John Ellenberger) #10

Been almost a year so I don’t have a specific answer but I would echo what others have said:

  1. The Z pulleys come loose a lot and all kinds of bad things can happen. Thats the first thing I check

  2. You need to be sure the bit is inserted deep enough into the collet and the collet is tight.

  3. Ball cutters do a lot better job at smooth bottoms than end mills IMHO.

All that said about once every few months my z apparatus gets so bollixed-up I find myself tearing it apart just to go through every piece for tightening/alignment. On my machine its always about the Z. Everything else seems to stay put.

(John Gowrie) #11

Thanks for your input! Just had a very similar issue on a job I ran… results were actually quite worse than your posted results… Going to be switching over to the ballnose bits for sure on all my pocket carves and just dealing with the extended length of time it takes to run them