Shopsmith Forums

dusty wrote:I do wish that I could come and watch you at the drill press for a while. You obviously have something going for you that I could learn from. I am not doing that well with this particular operation. However, I am doing some work in aluminum (not wood work). I have had to tighten tolerences for this job and not doing too well holding those tolerances. A machine shop this is not.

Start with a very small bit and gradually increase the size. By removing a small amount of material, the forces trying to 'mis-center' the bit are reduced. Not perfect, but 'better'.

What tolerances are you 'shooting' for?

JPG40504 wrote:Start with a very small bit and gradually increase the size. By removing a small amount of material, the forces trying to 'mis-center' the bit are reduced. Not perfect, but 'better'.

What tolerances are you 'shooting' for?

I am attempting to drill and tap a series of holes that ultimately must mate with holes and/or studs in other pieces. Two factors have given problems accomplishing these fits. The actual location of the holes (spacing from hole to hole) and angle of insertion.

Each hole (which is then tapped) needs to fit mate with holes on another piece. Slightly out of vertical leaves me with one hole mating up and the other slightly off line.

In doing this, I did discover that one of my Mark V tables is not flat (has a dip (.006") in the middle of the table. Just enough of a dip that when drilling small pieces the resulting hole might not be perfectly vertical. Don't know if this has always been this way or I have somehow introduced the deflection. I've been doing a lot of drilling but I do not think I was forcing anything enough to permanently flex the table.

To answer your question directly, I have no tolerance numbers to work to; just a need for a number of holes to match up and BE VERTICAL (90°) to the surface.

What size are the tapped holes? That size 'clearance' holes in the mating parts?

The clearance hole sizes in the normal drill index/tap hole size chart provides very little clearance to a screw of the thread size referenced.

With multiple holes, more clearance may be needed.

I would suggest(not knowing ANYTHING ELSE about your endeavor) to drill close tolerance clearance holes at the end holes of a sequence, and increase the clearance of the holes in between.

P.S. Re table flexing: That 0.006 maybe increasing as you apply drilling pressure. Place a stiff metal bar between the workpiece and table to minimize flex/dissipate stress. This IS one of the less desirable attributes of a ss table.

dusty wrote:I do wish that I could come and watch you at the drill press for a while. You obviously have something going for you that I could learn from. I am not doing that well with this particular operation. However, I am doing some work in aluminum (not wood work). I have had to tighten tolerences for this job and not doing too well holding those tolerances. A machine shop this is not.

Thanks for the smile Sarge! Actually I am not much of a woodworker but I'm having fun at it when I take my time. Good thing I'm not paid by the piece. Fortunately my current project (building dock sections and drilling holes for the aluminum leg brackets) is simple enough for even me to get good results. But I do wish I could land that drill bit exactly where I want it to to go.

For your project, would a doweling jig help?

Best,
Tom

tomsalwasser wrote:Thanks for the smile Sarge! Actually I am not much of a woodworker but I'm having fun at it when I take my time. Good thing I'm not paid by the piece. Fortunately my current project (building dock sections and drilling holes for the aluminum leg brackets) is simple enough for even me to get good results. But I do wish I could land that drill bit exactly where I want it to to go.

For your project, would a doweling jig help?

Best,
Tom

I don't really know what would help. I have failed on every attempt. Until yesterday when I found a machinist who is going to take me under his wing for the first set of holes only. He promised - no millings machines or fashion CNC smoke. He will show me how to get perfect alignment using nothing more than a drill press - the drill press he uses every day.

I know that I am about to learn and to probably be embarrassed.

Dusty, if you can possibly share that knowledge here, I'm sure some of us would appreciate it!

I second that request Dusty. I am still trying to finish my SS .5 project and the hole drilling is really eating up some wood and time. Thanks for the knowledge in advanced.
JIm