Facing tool keeps leaving .0005 to .001 lines down the part.

[turningwheels]

It's hard to explain, but when using my 2" facing tool on a 3.5 inch part, when doing the overlap, I get a distinct ridge that is about a thou in difference. even though that area is in the "overlap" there really shouldn't be any ridges. Tool marks yes, I get that. I did run the tool down one side and up the other, rather than bringing the tool back to the same side as the original cut.
The facing tool is this guy. https://www.amazon.com/gp/product/B00HQMXSM2/ref=ppx_yo_dt_b_asin_title_o04_s00?ie=UTF8&psc=1
Any suggestions on how to troubleshoot is greatly appreciated. Thanks.

 

[mmcmdl]

Your head may be a bit out . Have you trammed it lately ?

 

[Ulma Doctor]

put an indicator in a collet or otherwise attach it to the spindle and run the table under the dial indicator
any fluctuation of the table will show up on the indicator

 

[turningwheels]

The X Axis is less than a thousand across the whole board. the y axis is just under a thousand across 5 .5 inches. So it's hard to see why in 2 inches I would see such a big difference.

 

[darkzero]

The larger the diameter cutter & wider step over, the more noticeable it will be. You have to check tram. It sounds like you just moved the table around with an indicator stationary in the spindle? If yes that won't tell you anything in regards to your issue.

Assuming you had the part mounted in your vise in the orientation seen in the pic, ie that line parallel with the slots on your table & you were using the X-axis to make your cuts. You need to check nod (inline with the Y-axis). Mount an indicator in the spindle & sweep the front edge of the table to the back edge of the table (turning the spindle by hand).

 

[turningwheels]

Yep, the part is mounted in line with the X-axis. Dumb question coming, but if the table has a vise and t-nut slots how the heck to I sweep without hitting every bump in the way?

 

[darkzero]

When you sweep, as you get to a slot, pull the plunger back or needle up (depending on what kind of indicator you are using) to clear the slot, then let it back down carefully. As long as your indicator holder setup is rigid it shouldn't throw the reading off.

Or if you have two 123 blocks that you trust to be matched, you can place those on the table & indicate off those, no need to worry about the slots.

If using a dial indicator instead of a dial test indicator, if you have a button head indicator point, that can help with the slots also.

 

[turningwheels]

In my very unscientific testing, I clamped a parallel to the table, attached a Dial Indicator to the head and ran the y axis front to back. Out less than half a thou.
then I installed the drill chuck and mounted the Dial Indicator in that and ran it in a circle about 3 inches in diameter, picking up the shaft at each rail and placing it gently on the next one. Less than half a thou. Grabbing the spindle and pushing and pulling on it I can make it move about 3-5 thousand. same with the column.
I am wondering if it's the tool? Could the inserts be not seated in line with each other? Would that create the line down part on the X axis? It sucks to not know how to troubleshoot these little issues. Now I know why machinists charge so much. The setup and prep takes forever!

 

[turningwheels]

When you sweep, as you get to a slot, pull the plunger back or needle up (depending on what kind of indicator you are using) to clear the slot, then let it back down carefully. As long as your indicator holder setup is rigid it shouldn't throw the reading off.

Or if you have two 123 blocks that you trust to be matched, you can place those on the table & indicate off those, no need to worry about the slots.

If using a dial indicator instead of a dial test indicator, if you have a button head indicator point, that can help with the slots also.

I have both a .0005 DTI and a .001 Dial indicator. Using the Dial Indicator on this one in the manner you have described.

 

[darkzero]

Yes it can be from a number of various factors. Anything from locking the quill, loose gibs on the table and/or knee/column (not sure what kind of mill you have). Can also be from just lack of rigidity. Checking tram on the head is a good first start. Again, due to the diameter of the cutter, however much your tram is out, it will amplify that the bigger the cutter.

Try cutting with smaller step overs or a smaller cutter, if your tram is not way off, chances are the lines you feel will improve. Lock every axis that doesn't need to move when cutting.