# Kitless Cap and Body Alignment Issues



## burlywoodpecker (Jan 4, 2021)

I have been facing an issue whenever I turn kitless pens where the cap doesn't perfectly line up with the body.






These images are an exaggeration of the problem. The actual offset is about 0.1mm and is only slightly noticeable to the eye.
Previously I only had a wood lathe and made the assumption that his was inevitable due to the poor tolerances of the lathe. now, however, I have gotten a metal lathe and am experiencing the same problem. The only two possible explanations that I can think of is either that the mandrels I use are not centered, or somewhere during the threading operations I am threading off center. I have tried to see if I could address these issues but nothing I did worked to a satisfactory extent.

Firstly I tried several different styles of mandrels to see if a certain method of holding the blank caused it to become lopsided.


 
For mandrel A the blank came to a stop by hitting the shoulder and for mandrel B the blank came to a stop by running out of threads. A has worked better for me than B and I suspect this is because as the threads run out it pulls the blank in a certain direction...???

Secondly I tried changing my order of operations to see if I could improve the alignment. I noticed that when I mount the body onto the mandrel by the internal threads  (for the section) the external threads (for the cap) don't run smoothly, they wobble (the wobble you get when something isn't centered). I can tell by the flat spot behind the threads which doesn't run smoothly and seems to be spinning slightly out of axis. To me this implied that my tapping operation must be going into the blank at an angle, but maybe it is something else. 
I have tried tapping first, then mounting it on a mandrel to re-round the blank. after which I put the blank back in my collet chuck to thread it. I haven't had the chance to look into this more, and the one attempt I did this for also came out slightly lopsided. 

I find this an extremely annoying am hoping one of you has some suggestion as to why this is happening and how I could solve it.


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## McKenzie Penworks (Jan 4, 2021)

Did you make the mandrels or purchase them? There are some out there that I suspect I know the problem... I think maybe they were made from say 1/2" (or whatever diameter) rod that wasn't turned true prior to threading. You have to true up the rod prior to machining it because the raw rod will never be perfectly round. 

Quick way to see if it's the mandrels is to simply make yourself some mandrels. You can just make them from resin... quick and dirty.. just don't forget to cut in a bit of a relief at the bottom of the threads. I forgot to do that once and cracked my pen threading it onto my makeshift mandrel. Ooops...


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## Herman (Jan 4, 2021)

I would suspect the alignment of your counterpoint. In metal lathes there is an adjustment of centering. To start clean the busbar completely, lubricate with appropriate oil. I use a rectified bar, diameter 1/2 inch, with a 30 degree tip, approximately 10 inch length. Attach the bar to the plate, move the counterpoint and check the alignment of the tips. If necessary, adjust using the halen screws. There are three screws on the movable base of the counterpoint, one locks the movement, another moves forward and the last one in the opposite direction. Check your lathe manual for details.


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## burlywoodpecker (Jan 4, 2021)

McKenzie Penworks said:


> Did you make the mandrels or purchase them?


Thank you for your replies. I make my mandrels myself from aluminum and I do true up the rod before machining. I do however machine them in a three jaw chuck and use them with a collet chuck, but I doubt that is where the problem comes from. Visually the mandrel appears to be running very true, but I never actually checked with dial indicator.



Herman said:


> I would suspect the alignment of your counterpoint.


That could be the case. When I got the lathe I aligned it by using two dead centers and a thin piece of metal, but maybe that wasn't good enough. Do you make the rectified bar yourself or do you buy it?


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## bmachin (Jan 4, 2021)

What is your workflow? It should go something like this:

1. Turn the barrel round and mount in collet chuck or 3 jaw chuck.
2. Drill to depth for tapping for section threads.
3. Drill to depth for cartridges/converter.
4. Tap the section threads.
5. Turn to diameter for a sufficient length to cut the threads for the cap.
6. Cut the barrel/cap threads.
7. Move the barrel to the mandrel and shape.

 If your workflow resembles this, all of your threading is being done at one setup and should be concentric. Also, you mandrel has not yet even come into play.

One question that I have is: How are you holding your taps and dies? I assume that you are not single point threading with the lathe. If you are not using a tap follower and tailstock mounted die holder you are greatly increasing your chances of getting threads that are not straight. From you description of you problem it sounds like this may be the case.

One further comment. You can easily reverse the order of cutting the section and cap threads. It's mostly a matter of preference. Realize, however that tapping and die cutting threads are high stress activities and when you get to the point of performing the second operation (whichever it is) there is not a lot of material left to absorb that stress and it's really easy to break off that thin piece. My answer has always been to make either a snug fitting plug or collar to provide support during the final operation.

Checking your tailstock alignment is probably also worthwhile. Just checking with two centers should be sufficient.

Hope this helps.

Bill


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## Paul in OKC (Jan 4, 2021)

burlywoodpecker said:


> Thank you for your replies. I make my mandrels myself from aluminum and I do true up the rod before machining. I do however machine them in a three jaw chuck and use them with a collet chuck, but I doubt that is where the problem comes from. Visually the mandrel appears to be running very true, but I never actually checked with dial indicator.


I would check them with a indicator. Very rarely will a 3 jaw chuck run dead true. If you cam make the mandrel in a collet it would do much better, I think. The ‘A’ mandrel should do better, IMO. Do you drill and tap (or thread) the cap first, then put on the mandrel to do the OD?


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## Herman (Jan 4, 2021)

burlywoodpecker said:


> Thank you for your replies. I make my mandrels myself from aluminum and I do true up the rod before machining. I do however machine them in a three jaw chuck and use them with a collet chuck, but I doubt that is where the problem comes from. Visually the mandrel appears to be running very true, but I never actually checked with dial indicator.
> 
> 
> That could be the case. When I got the lathe I aligned it by using two dead centers and a thin piece of metal, but maybe that wasn't good enough. Do you make the rectified bar yourself or do you buy it?


This is a simple piece, rectified bars are often used as guide shafts in printers. I took advantage of an old scrapped Epson. I held it very close to the plate and machined the tip at 30 degrees. I use the same part to align the fourth axis of my CNC.


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## NT_2112 (Jan 4, 2021)

Check your concentricity.  I recommend something a dial gauge.  You can buy a kit with an adjustable mount or you can 3d  print a tool block mount like mine if you want to go cheap like me.  

Here is the one I printed:





Also check the alignment of your tail stock to your head stock.  If your tail stock is out of alignment any holes you drill will be offset from center.


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## More4dan (Jan 4, 2021)

0.1mm is about 0.004” and the typical metal lathe chuck has a runout of about that much. A collet chuck will get you closer. Or you could use a 4 jaw chuck with independently adjustable jaws a good dial indicator to assure very close to perfect alignment. You could also make sure you remount the blank in the collet at the same location anytime you take it out. Another option is one I do with the finial and screw them together before turning so the alignment is spot on. Or leave enough of a step between the cap and body that 0.1mm won’t show. 

When I use mandrills, I will always use a live center in the tailstock. It makes a big difference in keeping alignment. 

Danny

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## burlywoodpecker (Jan 5, 2021)

bmachin said:


> If your workflow resembles this


My workflow is completely similar to this except for the order of tapping and threading. I thread first and then I tap. for the actual cutting and tapping itself I use a tailstock mounted die holder and I use the tap in Jacobs chuck in the tailstock.


Paul in OKC said:


> Do you drill and tap (or thread) the cap first, then put on the mandrel to do the OD?


Yes I do. I tap first and then mount it on the mandrel to turn to the final dimension. 


Herman said:


> took advantage of an old scrapped Epson. I held it very close to the plate and machined the tip at 30 degrees. I use the same part to align the fourth axis of my CNC.


Ok thank you, I will give this a try.



More4dan said:


> Another option is one I do with the finial and screw them together before turning so the alignment is spot on.


I am going to try this for my next pen. 

thank you everyone for your replies. What I have gathered from them is that I have to pay very close attention to my tailstock alignment. I will try aligning it with the rectified bar first, and then with a dial gauge. Since I tap with a drill chuck in my tail stock any misalignment is likely to be the cause for this offset. 

Something I have a hard time wrapping my head around however is an off centered hole when drilling on a lathe. Theoretically when you are drilling at an angel wouldn't the spinning of the blank still cause the hole to be perfectly round? It would be slightly larger than expected but it would still be round right?


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## More4dan (Jan 5, 2021)

An off center hole would happen if your chuck or collet holder isn’t aligned with the center of rotation of the lathe. Think of drilling in a drill press and drilling your hole off center to the work piece. The hole would be round, just in the wrong location. 


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## bmachin (Jan 5, 2021)

More4dan said:


> An off center hole would happen if your chuck or collet holder isn’t aligned with the center of rotation of the lathe. Think of drilling in a drill press and drilling your hole off center to the work piece. The hole would be round, just in the wrong location.
> 
> 
> Sent from my iPhone using Penturners.org mobile app


Dan,
Situation is not analogous. In a drill press the drill is always aligned with the center of rotation. In a lathe with a misaligned tailstock this is not the case. The drill is offset from the center of rotation.

I'm not about to mess with the alignment of my lathe, but I suspect that there is a kernel of truth in what burlywoodpecker says. It seems to me that the outermost flute of the drill would act somewhat like a boring bar. The situation would be complicated by any pilot hole forcing the drill to center up leading to who knows what.

Bill


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## More4dan (Jan 5, 2021)

Bill in the lathe you would get a larger hole than the drill bit but round. If the chuck is off center and the tailstock aligned you would get the right sized hole but in the wrong place. Oversized holes come from misalignment. Off center holes will come from off centered holding of the material at the headstock. I do this on purpose sometimes with a  4 jaw chuck that lets you adjust the jaws independently. 

Danny


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## bmachin (Jan 6, 2021)

More4dan said:


> Bill in the lathe you would get a larger hole than the drill bit but round. If the chuck is off center and the tailstock aligned you would get the right sized hole but in the wrong place. Oversized holes come from misalignment. Off center holes will come from off centered holding of the material at the headstock. I do this on purpose sometimes with a  4 jaw chuck that lets you adjust the jaws independently.
> 
> Danny
> 
> ...


Sorry Dan. I misread. Was thinking of tailstock misalignment. Mea culpa.

I believe though, that in the previous post, the OP was talking about tailstock misalignment.

Bill


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## More4dan (Jan 6, 2021)

No worries Bill, the OP was about misalignment of the body and cap on the pen. 


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## burlywoodpecker (Jan 6, 2021)

thanks everyone. I appreciate all of your replies. I have spent some time realigning the tailstock on my metal lathe and it seemed to have taken care of most of the problem. A pen I just turned had a good alignment and I can't detect any offset by eye. I will turn a few more pens to see if this will stay the case.

Renzo


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## TonyL (Jan 6, 2021)

I agree with Dan. The same thing happened to me and I traced the cause to what Dan said.


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