Drilling On Milling Machine

[faavs730222]

Hi All,

I am still very new to Milling Machines (metal working as a whole for that matter).

I have a RF45 Clone milling Machine (Zay7045fg).

I have Harold Hall's Book "Lathework, a complete course", I am busy with the first project, the Mini Surface Gauge. It requires to drill 4 x holes 10mm apart on a shaft. I decided to do it on the milling machine.

I used my edge finder to find the edge of the shaft on X and Y to get datum markers.

I advanced the x axis 10mm end center drilled the firs hole. Then I advanced it another 10mm and
center drilled the second hole. I continued and center drilled all 4 holes. then I went back to my original position on the x axis and from the datum advanced it 10mm to the first center drilled hole and drilled it 6.1mm. I did all 4 holes. Again I went back to my original datum position on the X Axis and Counter shank the first hole, but the counter sink were off center, although I started form the original position.

So what would be the correct way to approach this job? To center drill the first hole, then drill it to size and the counter sink it, and then proceed to the next hole?

I made sure that I take up the back lash.

I do not have a DRO on the milling machine, so I used the lead screw dials.

Any suggestions?

 

[jpfabricator]

My procedure is if possible do all opperations on each hole before advancing to the next. My .02¢.

Sent from somewhere in East Texas Jake Parker

 

[wrmiller]

On a non-DRO equiped machine, I would do what Jake said and finish each hole before moving onto the the next.

 

[Bob Korves]

+1. Only down side is lots of tool changing. You should also make sure you do not need to move the head up and down when changing tools. That will often move the spindle position away from the original position, causing the kind of errors you are seeing.

 

[Paul in OKC]

If you went straight to the first number from the last, you did not remove the backlash from the screw. With no DRO, you have to move the table in the same direction to your mark each time. When going from the last to the first, go back past the first number then come to it in the same direction you moved to set the datum point, and to each additional hole. Clear as mud?

 

[faavs730222]

Thank you very much for all the info. Two mistakes I know I made is, I did move the head up and down to change tools. And I did not take up the back lash in the original direction. Stupid mistake.


Sent from my iPhone using Tapatalk

 

[Bob Korves]

When you have a mill that uses head movement instead of knee movement, when you are setting up your work and your mill you should try to find a head position and tool choices so that no head movement is needed for the entire job. Sometimes that requires some thought, like using a collet to drive a drill or using stub length drill bits to keep the vertical envelope required small enough to do all the work with the quill travel alone. It even helps on knee mills for critical work.

Edit: It also makes the work go faster and easier.

 

[sanddan]

Bob, on an RF45 clone the head moves on dovetails, no different than the X and Y axis. You can't move the head accurately in the Z direction, as you said that's what the fine feed is for, but it won't lose the X and Y position when moved. It's one reason that they are used for CNC conversions as the head can move accurately when a ball screw replaces the Z lead screw.

 

[Uglydog]

Consider your tolerances.
As JPFab states leaving in place will be the most accurate. However, Bob K point is also valid.

I don't have DRO and have avoided it. I do alot of counting and need to account for backlash.
Really depends on what you want. I find the handwheels relaxing. A significant break from our gee-whiz-techno world.

Bob Korves above suggestions are solid!!

Daryl
MN

 

[Bob Korves]

Bob, on an RF45 clone the head moves on dovetails, no different than the X and Y axis. You can't move the head accurately in the Z direction, as you said that's what the fine feed is for, but it won't lose the X and Y position when moved. It's one reason that they are used for CNC conversions as the head can move accurately when a ball screw replaces the Z lead screw.

If the head is moving up and down on gibbed dovetails, well, that changes the equation somewhat. In theory, it should be just as accurate as a knee mill. However, I have read too many stories of people who say the geared head on these machines is difficult to adjust and to tram, and that the column is often not square with the X and Y axes. Really, on any manual machine, regardless of type or origin, you should only be using one axis to do the work while all the other axes are locked and left locked until done, if possible. Note that if the head is out of tram, left or right, then the spindle takes up a PARALLEL position as the head moves up and down. If the tram is good, but the column is not square with X and Y, you get the same result moving the head up and down, a parallel offset.