Need tips on drilling a long thin through hole

[tjb]

Okay, all this discussion is causing me to wonder if I need to re-think this project. I added DRO to my lathe a couple of years ago and ran the z-scale along the backside of the cross slide. Has worked great, but it presents two complications. First, the scale and reader stick out the back of the cross slide by approximately two inches and interfere with positioning of the tailstock. Second, the set screw that locks the cross slide is accessible but is directly below the reader rendering usefulness doable but difficult.

I saw a myfordboy video on youtube where he added DRO to his lathe, and made an extension on the back of his cross slide so that the scale was mounted to the rear of center. I would like to do the same thing and, on my lathe, I had the idea of simply making a 4 1/8" extension (my available space) to attach to the back of the cross slide. That distance would be sufficient to allow proper use and access of both the tail stock and the set screw.

It would be a rather simple matter to mill a piece of 5/8" aluminum, which I have on hand, to 2" by 4 1/8" and bolt that to the end of the cross slide. The long holes would only be necessary for a long #10 screw or threaded rod to snugly slide through, hence, the need for accuracy. The idea seemed simple to me, but now, I'm beginning to wonder. Is the potential for wandering significant enough to distort the alignment? I've never drilled anything this long and narrow, so I'm in uncharted waters. I can think of a couple of other ways to attack this but, frankly, this seemed to be the easiest and most straightforward. So much for my logic.

What do you think?

Regards,
Terry

 

[MrWhoopee]

Ah, now we're at the meat of the matter and the job looks entirely different from the original description. Cut a window in each side of the piece of aluminum to allow the use of short bolts. Here's a pic of how I did it on my Heavy 10.

 

[mikey]

Terry, it might help to show a pic of the area involved, with the hardware you're trying to install. I bet the guys could come up with an alternative (like MrWhoopee's above) to extremely deep hole drilling.

 

[pdentrem]

Mr Whoopee’s solution is very good. What about the weight that is cantilevered off those bolts? Maybe give a thought of using hollow extruded stock or mill a slot on the underside and epoxy a tube for the attaching hardware.
Pierre

 

[tjb]

Ah, now we're at the meat of the matter and the job looks entirely different from the original description. Cut a window in each side of the piece of aluminum to allow the use of short bolts. Here's a pic of how I did it on my Heavy 10.

View attachment 307422

Thanks, Mr. Whoopee. That's exactly the thought that's been running through my mind, but I wasn't sure it made sense. That is now definitely way up high on the alternative list.

Regards,
Terry

 

[tjb]

Terry, it might help to show a pic of the area involved, with the hardware you're trying to install. I bet the guys could come up with an alternative (like MrWhoopee's above) to extremely deep hole drilling.

You're right, Mike. I didn't really see drilling those holes, initially, as being such a complicated issue. I really expected to get a simple answer with regard to feed rates, tool material, etc. On the surface, it seemed pretty straightforward, so long descriptions and photos didn't strike me as particularly necessary. So in the grand scheme of things, I'm glad I asked. No telling what a disappointment it may have turned out to be.

Unfortunately, I can't get out to the shop this afternoon to take pictures, but Mr. Whoopee's photo is right along the lines of the direction I was headed. Looks like he made his the full width of his cross slide; I was only going to make mine 2" - easily wide enough to mount the hardware. Also, I have some aluminum extrusion end pieces left over from who-knows-what that might be worth considering a la Pierre's suggestion. Never even thought of that one.

Thanks again.

Regards,
Terry

 

[tjb]

Mr Whoopee’s solution is very good. What about the weight that is cantilevered off those bolts? Maybe give a thought of using hollow extruded stock or mill a slot on the underside and epoxy a tube for the attaching hardware.
Pierre

Thanks, Pierre.

That one's worth considering. See my answer to Mike, above.

Regards,
Terry

 

[Cadillac STS]

Since you mentioned doing a test piece and it is just aluminum consider making the test piece(s) the same size of part you need. That way if your experiment works you are done.

 

[Cadillac STS]

Consider drilling the deep hole large enough to put the head of the screw in. Drill down with 1/2 inch drill for example to half inch from the bottom. Then drill your precision placement hole half inch through the face side so it will fit right where you need it, not needing to be exactly on center with the big hole.

think deep deep counter sink for the bolt head.

Then use a 1 inch bolt Deep down inside the larger hole.

 

[tjb]

Consider drilling the deep hole large enough to put the head of the screw in. Drill down with 1/2 inch drill for example to half inch from the bottom. Then drill your precision placement hole half inch through the face side so it will fit right where you need it, not needing to be exactly on center with the big hole.

think deep deep counter sink for the bolt head.

Then use a 1 inch bolt Deep down inside the larger hole.

That's a good idea which I had considered, but I'm only starting with 5/8" stock. I've been pondering this today and thought about using some 3/4" stock I have available. We'll see what we come up with.

Regards,
Terry