drilling blanks with a lathe issues

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musicman

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Jun 24, 2019
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Hey Everyone,
I'm a newbie to pen turning, and I am having some issues with drilling a slimline and sierra blank. I have read some people's discussions with the similar problem I am having, and I tried implementing various people's suggestions, but I am still having some issues. I'm using a new Lugana 1216 lathe with a NOVA 48232 G3 Reversible Wood Turning Chuck, NOVA 6034 Pen Plus Jaws, and Heavy Duty 1/2' Keyed Drill chuck (from Amazon/Woodriver). In an attempt to make some slimline pens out of acrylic, I proceeded to use a 7mm brad point bit that I purchased from either woodcraft or penn state. After completing the drilling at 550rpm's, the pen tube would simply fall completely through the hole. I have a feeling it's not supposed to do that. I tried using a 17/64 standard drill bit running the lathe at 550 rpm's, and the problem seemed to correct itself; however, the entrance hole is slightly larger than the exit hole. When I flip the blank around thus allowing the drill bit to enter the exit hole, I can get it to enlarge thus matching the other end's diameter. The tube doesn't fall out, but it is somewhat snugged and with very little effort to get out. I have made about seven slimline pens, but I have a feeling this method is not the best/standard.

With the sierra, I tried using the 27/64 brad point and the hole is way to large for the tube. Since I don't have a stub bit, I used the 17/64" as a starter hole, and it did not help. I took the same approach as the slimline and used a 13/32 standard drill bit running at 550rpm. Again, having the same outcome as the slimline. I made two sierra pens.

I have double checked the pen jaws, the blank in the jaws, the drill bit, and everything is locked with no movement. I have tried the pencil in the drill chuck, hand turning the blank and it makes a point. I made sure the drill bit was far enough in the chuck, I entered the blank very slowly and drill only about 1/2" to 3/4" at a time. I retract the quill and pull the tailstock back with the lathe off and then I reinsert the drill bit to the depth of the already drilled hole, turn the lathe on and extend the quill another 1/2 to 3/4". All of the drill bits I am using are new. I am open to any and all suggestions.
 
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TonyL

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Mar 9, 2014
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It appears that you are doing everything correctly and checked for everything being plumb, square, true etc - you also have excellent tools. , It is ok for the tube to slide through as long as you can't see any spaces/void between the inside of the blank and outside of the tube (I get those sometimes and use my centers to open expand the tube slightly).
I would try drilling no more than 1/2 inch at a time and use this to keep things cool. https://www.amazon.com/Bostik-Dri-Cote-Aerosol-10-75-oz/dp/B0000223UC

Many folks don't use any lubricant and drill more at at time than I suggested with outstanding results. I drill resins at 700 rpms and wood at 900 rpms - but remember, I use the lubricant during each plunge.
I also make sure my tailstock is locked down and I hold the jacobs (sp?_ chuck) while drilling and withdrawing. I withdraw with the bit still rotating. I don't know if my method will work for you. I am just offering some help. And FWIW, I do all of the above and sometime still mess-up. I do like start the hole with a short center drill.


I would suspect:
Run out
Something not being seated right: chucks, jaws, drills, etc.
Bent bits

But you have checked all that.
 

Warren White

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Aug 27, 2014
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Livermore, CA
I am not sure that I can give you all of the answers you need, but I will jump in, hoping that I can help a little. First, I have not had much success with the Nova G3 Pen Jaws. I found that they do not close on the blank all of the way down the blank. My jaws weren't parallel at all, and Teknatools replaced both the chuck and the jaws, but I still had the same problem. It seemed to me that you must have everything parallel in order for the hole to be right. I bought a Vicmark VM120 chuck and their pen jaws and they are much better. Second, your tail stock and head stock have to be exactly even and the travel has to be exactly parallel. One issue that you need to be aware of is that your drill chuck (I assume you have a MT2 fitting drill chuck) needs to be tight and held with your hand as you drill to make sure that it doesn't add to any misalignment issues. Another issue is just an observation; I don't like a real long drill bit, because the more length between the tail stock and the end of the bit adds to the possibility of poor alignment. I use a cheap set of drill starter bits to find the center of the blank and then switch to the drill bit. In the spirit of that observation, I start drilling with my tail stock only out 1 inch or so, and I bring it back to that each time I start a new attack on the hole. I also don't put the bit in a started hole with the lathe turning. I stop the lathe and gently put the bit in until it bottoms out and then turn the lathe back on. (I may get some negative feedback on this....)

Well, others will certainly have better advice, but this is my 2 cents worth. (And that might be all it is worth)
 

magpens

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Hi Nick !! . Welcome to IAP !!

First off, .... and I hope that I don't say the wrong thing .... I would never use brad point drill bits for making pens. . Just use standard jobber size machinist's drill bits. . Some might disagree with me but I tried brad point drills and never found them to my liking. . Some companies will sell you specialized drill bits for drilling pen blanks ... quite expensive bits, actually ... they have a more acute angle in the tip and they are longer ... I never found them really useful either. . So my fall-back was jobber bits and after 2000 pens I stick with the jobbers. .

I cannot explain the phenomenon that you mentioned about the brad point bits giving you a hole that is larger at one end ... requiring you to make another pass with the blank reversed ... quite weird. . I have the feeling that a brad point should never be used to re-drill a hole as well as never to be used for pens ... especially if you are drilling acrylic.

Drilling pen blanks correctly can be a ticklish business and I think many newbies find it that way. . It is partly because of the way that pen kit brass tubes are designed. . You will already be well aware that the recommended drill size of 7 mm is slightly bigger than the diameter of a so-called "7 mm brass tube". . And it is also a little bigger than it really needs to be to get a good fit. . There is, of course, the matter of leaving room for the glue, but "they" overdo that in my opinion. . Unfortunately, we are stuck with this situation and just have to make the best of it.

But using brad point drills, it would seem from your described experience, just makes matters worse if the resulting hole has non-uniform diameter.

So, my advice would be to use jobber drill bits .... the ones you get in those metal-boxed sets at a tool store ... make sure they are HSS (high speed steel). . Home Depot sells similar sets, but I don't think they are as good quality as you get from a "real" tool store. . It is worthwhile spending $100 or so and getting a complete set. . Eventually, I would recommend that you also get a set of letter-sized bits, and also a set of metric-sized bits. . Sounds like a lot of money to spend on just drill bits. . But even if you never use them all, you will use enough of them that you won't be sorry ... if you take your pen-making seriously.

Here is a little story about drilling for Sierras that might support what I just said.

The recommended drill bit for a Sierra is 27/64". . That drill bit makes a hole 0.422" diameter. . If you measure the Sierra brass tube, you find it is 0.410" (plus or minus 0.001" or so). . So obviously, the hole you drill with the recommended drill bit size is going to give you a sloppy fit, and you have to take up the "slop" with lots of glue. . I personally don't like doing that. . So if you happen to have a letter-sized drill bit of "Z" size, which is 0.413" diameter, you get a much better fit for your Sierra brass tube. . That's what I use all the time. . Now, I have to be careful in telling you that because while that works quite well for "hard" pen blanks like acrylic and many hardwoods, you will not get as good results with softer woods ... in fact, your fit could be quite tight if the tube goes in at all. . So some discretion and experience does come into play. . I can only surmise that "they" recommend the 27/64" size drill bit, for the Sierra, in order to cover all bases. . But the result is a sloppy fit many times. . Just my opinion based on 2000 pens of experience.

Bottom line in my opinion is buy jobber drills ... at quite a few tool stores you can buy individual sizes so you don't really need to buy a full set. .
But buying a full set could work out cheaper in the long run. . Also save up some money and buy good quality ... letter-size bits and metric also.

Did I say "Welcome to IAP !!! " ? ... :) :):)

Oh ... I should add ... get yourself a pair of digital-readout calipers for measuring brass tubes, pen blanks, and hole sizes ... totally worth the $25 or so. . Eventually you will want to turn your pen blanks "between centers" and without bushings, so the calipers will be "a must-have".

Also, do a Google search and bookmark a "Drill size conversion chart" that you find to your liking ... there are many, so choose the one you like best and you will without doubt use it often. . It should include the SAE (jobber) sizes, letter sizes, and metric sizes with decimal equivalents for all drill diameters.
 
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jttheclockman

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I am probably going to repeat a few things that were already said but that just reinforces what has been said. I agree that brad point bits do not belong in pen turning and others can disagree but that is my feelings. A machinist bit is the way to go. I also agree that a small starter bit should be used to start the hole because a bit will seek its own path. With the shorter sturdy bits will keep this on a straight path.

I too think that chuck the pen jaws do not close parallel I use this chuck because I tried PSI version which plain sucks. The jaws wore out and was told twice that replacements were sent but never got them so I believe that was a lie. Not a fan of PSI. http://www.timberbits.com/vicmarc-pen-blank-chuck

I am not sure if it was mentioned but when using the drill chuck in the tailstock you need it to be seated firmly. When starting to drill you need to hold the chuck steady with the left hand and advance with the right till it starts the hole. I like to steady that chuck throughout the drilling process. Some people like myself drill all the way through and some stop just short of the end and cut off the small amount. That is fine if the blank is long enough. Your call on that one. You can do this and drilling on a lathe is more accurate than a drill press.

Oh and one more thing, make sure the bit you are using is straight and not bent. Roll it on a metal surface.
 

randyrls

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Feb 2, 2006
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Harrisburg, PA 17112
Nick; Welcome! You want a sliding slip fit on the pen tube but no slop. The library is still being rebuilt after our recent software change. This is my drill bit chart. I print the instructions and have a full set of 115 drill bits and a metric set. I drill starting undersize increasing until I get the the correct fit, then write down the correct drill bit. This is often NOT the drill bit suggested on the instructions. For slimlines I use an "I" (letter) drill bit. Bit sizes for acrylic vs wood are sometimes different. Your situation may vary. Wood will drill slightly smaller (.003" or so) holes.
 

monophoto

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Saratoga Springs, NY
the entrance hole is slightly larger than the exit hole.
This suggests a potential alignment problem.

You need to verify that the headstock and tailstock of your lathe are properly aligned. To do that, mount a cone live center in the tailstock and extend the quill as far as it will go, put a standard spur drive in the headstock, and then slide the tailstock up to the headstock. The tip of the live center should meet the tip of the spur drive exactly - both in the horizontal and vertical planes. Its not unusual for there to be a slight misalignment, especially in the horizontal plane, and most lathes have the ability to realign the headstock to compensate this out.

It is also possible for there to be some 'wiggle' in the tailstock - a tendency for the tailstock to rotate very slightly about a vertical axis when it is not locked down to the bedways. This happens when the bottom of the tailstock is not machined perfectly to the width of the gap in the bedways. There really is no fix for this - you just have to work around it and that may mean accepting the fact that the hole that you are drilling is ever so slightly conical with the entry end a bit larger than the exit end. You can minimize this tendency by mounting the blank in the headstock, and then facing off the end that will be the entry end. With the blank rotating, use the tip of a skew to cut a small centering dimple. Then, to drill the hole, align the tip of the drill bit in that centering dimple before locking down the tailstock.

If you want to be really precise, you can start the hole using a centering bit, drill an initial hole with a small diameter bit, and then enlarge the hole to the desired diameter.

The point that others have made about brad-point bits is valid - they are fine for casual drilling, but they aren't idea for precisely centered holes. For precise centering, you need to aligh the conical portion of the tip of the drill bit with the diameter of the hole - which means using a standard 118 degree machinists bit, and having a conical starter hole that you align it to.

Final point, some slight misalignment can be dealt with by using a good gap-filling adhesive to glue the brass tube in place. Epoxy and thick CA are popular choices, and my experience with polyurethane glue has been excellent.
 

musicman

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Jun 24, 2019
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Location
Texas
Thank you all for taking the time and responding to my post. Your feedback is greatly appreciated, and I will use it for this issue. I like to add this action that I took in order to help pinpoint the potential problem. Two of the blanks that I previously drilled had a very tight fitting for the tube. Since I am planning on painting the inside of the blank, plus using CA glue, I was little concerned that tube might not fit. Therefore, I decided to place the blank in my pen jig (from Rockler) and use the cordless hand drill. I used the 7mm brad point for the slimline, and then use the 27/64 brad point for the sierra. The hole was smaller than the one's created from the lathe. When I place the tube in the blank, it will come out from the other side, but does not drop out like before.

I do plan to recheck the alignment with the headstock and tailstock. That was the first thing I checked once I opened the box, and it was aligned. Thank you for the drill bit and chuck suggestions and where to get them. Thank you for the calipers suggestion. I actually purchased one after making my first pen. I tend to be a perfectionist at times. Sometimes, it is a curse. LOL

By the way, do any of you have a YouTube channel?
 

pshrynk

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Dec 6, 2017
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Lake City, Minnesota
I was going to say to make sure the tailstock is locked down tight, but Louie beat me to it. Lots of good advice here. Always the case at IAP...
 
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