Do you make your bushings off a mandrel?

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low_48

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(Edit; I asked about a mandrel, but should maybe have used a different term. I don't mean a pen making mandrel. Maybe a pin that locates in the bored hole in the steel blank. Used to locate the piece of steel for the rest of the machining. Edit} For the best accuracy, do you bore the hole, they mount through that hole to machine the rest of the bushings? Or, do you use center drill, then jobber length drill, to minimize the chance of runout? Do you ream the hole, or just drill? Just thinking about reducing tolerances to make great bushings.
 
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low_48

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I added an edit. I'm asking about the machining of making my own bushings. I'm wondering if an error will be put into the bushing if not machined off the first operation of boring the hole, compared to just grabbing the od of the steel and doing all the machining operations. Isn't the relationship between the hole and the pilot diameter for the tube the same for either TBC or on a mandrel?
 

KBs Pensnmore

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The easiest way would be to grab your piece of bar, around 5/8" (16 mm) or bigger in the 3 jaw chuck, leaving out enough to part off later, and centre drill it, then drill to just under the "D" size to the length required plus a 1/4", then run a "D" size bit through to the end. While it's still held in the chuck, turn the OD to the size required, and then part off to the length required. Remove any burrs.
As everything is done with out resetting the stock, it therefore should be perfect.
Kryn
 
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Paul in OKC

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The ones I have made drilled and turned close to finish diameter, then finished between centers. Works very well. Kryn's method works well, also. With using a center drill, then correct size bit, the short length of the bushing generally keeps things well in line.
 

Ed McDonnell

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If you are using one of the small 7x12/14/16 metal lathes, then try and get your chuck mounted with a minimum of run out before you start making bushings. They can be off a surprising amount if you aren't careful in mounting them. I can get my collet chuck mounted with no run out if I play around with it. With a three jaw chuck, sometime moving the jaws to different positions can improve things (mark the jaws and chuck to keep track of what you are doing if they aren't already marked for you).

It's a pain to take the time to eliminate / minimize all the little errors through the pen making process, but doing so avoids situations where they compound into a big error by the time you are done.

Ed
 

magpens

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Why do you want to make your own steel bushings? When you can buy them it is hardly worth the effort to make your own. Admittedly, some sources of bushings seem to be overpriced. But it's still cheaper to buy them ready-made when you consider all costs of making your own.

In any case, relying on bushings and mandrel for accurately turning pen blanks is probably a mistake, IMHO, although I started off using this method.

I now use bushings/mandrel to do rough turning only but not to final size.

I do all my accurate turning using the TBC method, without bushings, after I have carefully squared up the ends of the blank with the brass tubes.

Sometimes I go back to bushings/mandrel for final sanding, polishing and finishing after the accurate size and shape has been established with TBC.
 

low_48

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Why do you want to make your own steel bushings? When you can buy them it is hardly worth the effort to make your own. Admittedly, some sources of bushings seem to be overpriced. But it's still cheaper to buy them ready-made when you consider all costs of making your own.

In any case, relying on bushings and mandrel for accurately turning pen blanks is probably a mistake, IMHO, although I started off using this method.

I now use bushings/mandrel to do rough turning only but not to final size.

I do all my accurate turning using the TBC method, without bushings, after I have carefully squared up the ends of the blank with the brass tubes.

Sometimes I go back to bushings/mandrel for final sanding, polishing and finishing after the accurate size and shape has been established with TBC.

It's really all about precision. I've been at this over 10 years, and have always been surprised at the lack of good tolerances in bushings. I'm retired now, have a mill and a lathe, so why not? They will be for TBC, but I want the absolute smallest amount of runout possible. For what little lathe work I did as a model maker, I always got the least runout using a boring bar on the lathe. Always better than off a drill. I just wanted to see how others did it, and didn't want to hijack the other post on making bushings.
 

magpens

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OK, thanks for replying. As you can tell from my first response, I have largely gotten away from using bushings, relying instead on using my calipers with TBC.
 

BSea

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Why do you want to make your own steel bushings? When you can buy them it is hardly worth the effort to make your own. Admittedly, some sources of bushings seem to be overpriced. But it's still cheaper to buy them ready-made when you consider all costs of making your own.

In any case, relying on bushings and mandrel for accurately turning pen blanks is probably a mistake, IMHO, although I started off using this method.

I now use bushings/mandrel to do rough turning only but not to final size.

I do all my accurate turning using the TBC method, without bushings, after I have carefully squared up the ends of the blank with the brass tubes.

Sometimes I go back to bushings/mandrel for final sanding, polishing and finishing after the accurate size and shape has been established with TBC.
If someone has a metal lathe, I don't see where it cost more to do your own. If you want to figure your time, then maybe. But since this is a hobby for most of us, the only real cost is less than $2 of tool steel to make a set of bushings.
 
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