Drilling with my lathe

[projectnut]

I would stick with using the tailstock for drilling. Even with a depth of only 1" I would peck drill the hole before reaming. As mentioned the walls of the part may be flexing. Overloading the drill flutes can contribute to less than smooth or oversize holes. Moving the tailstock by hand should give you the feel as to when the flutes are loading.

My personal preference for reamers are the spiral flute style. All styles work reasonably well, but the spiral flute style can better handle interruptions from slots and cross drilled holes.

I would do a couple practice pieces with all but 1/4" or less captured in the collet. Don't over tighten the collet to the point it will cause the wall of the tube to collapse slightly once the hole is drilled. Also be sure the tailstock is centered properly. I use an Edge Technology alignment bar like this to be sure:

Tailstock Alignment Bar 27-000

The Tailstock Alignment Bar by Edge Technology is used to align the tailstock to the headstock. Accurate alignment is critical to eliminate any taper in work pieces that are supported by the tail stock. Our Tailstock Alignment Bar makes the process of tailstock alignment fast, easy and accurate.

www.edgetechnologyproducts.com

I usually align mine to .0005". That's close enough for most operations.

 

[kentuckyjim]

I appreciate your questions. The workpiece is extended maybe 3/16” beyond the collet. I face the drill a pilot before drilling. I have been pecking by ear. If it sounds different I back out. The walls of the material .016 to .020 per side or
.032 to .040 over the hole size. I usually can tell when the drill is dull
By the temp of the drill and the effort needed to move the drill. Better drills and sharp drills were one of the best tips I’ve been given.
I hadn’t considered clamping pressure. I did change my order of work process changing the fitting of the male slide from last to first to insure I didn’t have it bend away during machining.


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[Tozguy]

I have a prior preference for straight fluted reamers unless there is a particular problem using them.

 

[darkzero]

I really appreciate the feed back! One further question if I may. I see
In catalogues spiral, reverse spiral, and straight reamers. Is there a style that is better for my application?
Thanks again to all who have responded so quickly.


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Spiral flute reamers are good for holes that have a keyway slot or hole for a setscrew or a pin, etc. Straight flute is not good for that. Spiral direction is just like spiral flute taps. RH spiral for blind holes so the chips tend to push out the back. LH spiral for through holes where the chips get pushed forward. But spiral flute reamers cost more than straight flute.

 

[kentuckyjim]

Dark zero
Thanks for the reamer info. I have straight reamers. I probably would be better served by rh flute which would eject the chips. I assume that chips in the flutes might compromise the finish of the hole you’re trying to clean up


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[Dan_S]

what material are working with, and what is your tolerance for concentricity?

but you might be able to find tubing that is very close to the final size you want, and then you would only need to ream it to size.

 

[kentuckyjim]

Nickel silver rod is what I use most of the time. Duronze for rods needing extra strength. You are correct about the use of tubing. The best ferrules are made from drawn nickel silver tubing which is said to work harden during the process.
It is hard to get in all the sizes needed and is expensive for a hobby builder. The required slip fit of the male and female requires a round smooth female socket and a round smooth male that slides in snuggly with no hang ups. It will pull apart with a nice pop.


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[mikey]

Lots of good info here.

I agree with Will about the spiral flute reamers but for most of us, straight fluted reamers will be fine. I've used both RH, LH and straight and all work well in aluminum. The trick is to come in on size and of all the considerations we have when using reamers, this is the trickiest. The rest is just mechanics - yes, use a properly aligned tailstock, use a good drill chuck (Albrechts are good) because it makes a difference, make sure the shank of the reamer is free of defects and dirt before chucking, etc.

You should know that the material being reamed affects the reamer size chosen. If you have an on-size reamer, say 1/8", and expect that to produce a 1/8" hole then you may be disappointed, depending on the material. I'm attaching something from Yankee Reamers you may find useful. The bottom line is that if you need a specific hole size then keep the material and drill sizes in mind.

I wanted to comment on making the hole but this is just anecdotal and based on my experience; it is worth exactly what you're paying for it. You will find that a spotting drill will start drills more accurately than a center drill. Be sure the spotter you use is appropriate for your drill geometry (120 degree spotter for 118 degree drills, 140 degree spotter for 135 degree drills). I find using two drills before the reamer to give the best results. The first drill is one size smaller than the pre-reamer drill and the second drill is the pre-reamer drill that is calculated to come closest to the required hole size before running the reamer. This gives me the cleanest, most accurately drilled holes of all the methods I've tried. This matters because a reamer can typically straighten a hole a maximum of about 0.005" and make the hole come out straight and on size. Beyond this, you have to bore it. Since drills do not drill straight, round holes, the way we drill them is important. Multiple step drilling is not a good idea when reaming. The reason is that smaller drills will tend to bend and drift. Each subsequent drill will follow that bent hole and so will the reamer. Better to debulk it once with a drill big enough not to bend too much, clean it up once, then ream it.

If you must ream a blind hole then use a carriage stop to halt the reamer at the right spot. You do NOT want to bottom reamers in a blind hole; they won't last long. You must drill deep enough so you can stop the reamer before it bottoms.

Use good reamers. For most holes, I use Precision Twist Drill reamers but when I need a really precise hole I turn to Alvord Polk reamers - they are the best I've used. If you do a lot of reaming, it pays to use a good reamer and keep them sharp.

I've learned to ream slow, about 100 rpm in most materials. I know there are recommended speeds and so on but you will be feeding manually and this slower speed will allow you to feed so that you can feel a slight resistance to the feed. This ensures the reamer is continuously cutting but without a lot of side force that will cause it to bend if you feed to fast or build too much heat if you feed too slow. Cutting oil that is appropriate for the material is a good idea.

I also find that feeding only on the way in produces the best finish and accuracy, and the reamer stays sharp longer. I suggest you feed in to the stop, shut the lathe off and then withdraw the reamer. Try it and see. The hole will be more accurate.

Good luck!

 

[darkzero]

Dark zero
Thanks for the reamer info. I have straight reamers. I probably would be better served by rh flute which would eject the chips. I assume that chips in the flutes might compromise the finish of the hole you’re trying to clean up


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I was just about to post, I agree with Mike, straight flute reamers will be fine. If you have them already use em. Buying a spiral flute drill is not going to give you better results or even a more accurate sized hole. Reamers don't remove a lot of material so chances are slim that they'll pack up with chips & affect the hole size. Not saying that it can't happen but it's never happened to me. I've never needed to ream very deep/long holes though.

 

[darkzero]

Eddy already covered it but the advantage to a tool post pointed drill is the ability to drill much deeper holes & quickly retract like for peck drilling which is also required for drilling deep holes.

If your lathe is rigid enough & you are brave enough can power feed drill. But with a QCTP mounted drill, under heavy loads there are chances you can spin the the QCTP since the drill holder is mounted to the side of the QCTP.

I have one made by Edge Technologies, since it mounts in front of the tool post stud there's little chance of twisting the TP. Their design makes it easy to align. The chuck is mounted on a free floating plate. Loosen the plate, install the included dowel (which stores in the tool) in the lathe chuck, chuck up on the dowel, then tighten down the plate. But this design is less rigid (has more overhang) so I don't do any heavy drilling with it. I use it when I need to drill holes longer than the travel of my TS ram.