pen turning

[Samfire]

Hi, I have purchased a 7mm pen turning kit from a well known supplier and made a few slimline pens. I am enjoying making them because they are quick projects to fit in between other duties. Anyway, I would like to start making some of the other pen styles I have seen.

I have noted that most other pen kits require 8mm or 10mm drill bits to take bigger tubes. So my question is this. Do I need to purchase bigger mandrel to make these kits or do the bushes sort it out.
To some of you the answer is probably obvious, but I have only been turning for 5 months and the learning curve is quite steep.
Sam

 

[woodpig]

Provided the bushes fit your mandrel you should be fine.

Sadly there is no standard for pen turning mandrels and they are available in a variety of different sizes. Some folks like the larger diameter mandrels because they are less whippy than the thinner ones. Mandrel savers are worth a look if you don't use one.

 

[Samfire]

Thanks for the quick reply and the good new, I was hoping the answer was in the bushings. I have just purchased a mandrel saver but haven't used it yet.
Thanks again
Sam

 

[Dalboy]

Each pen kit has different bushes to be able to produce it which can work out expensive I tend to use the tapered ones and measure to the size required this does also have its draw backs as if you tighten them too much you can flare the tube end and in some cases split the blank you use.
Use the pen saver is a must as if you use the nut on the mandril it has been known to slightly bend the mandril which in turn makes the pen barrel not match to the fittings

 

[woodpig]

When I first looked at pen turning I was quite confused by the number of different size mandrels on the market. The fact that I wasn't interested in slimline pens and the comments about thin mandrels bending prompted me to look at the larger ones. I soon found out that they were not commonly available over here. My solution was to buy a cheap collet chuck from China and a piece of 7mm silver steel. Total cost was about £12. Most bushes etc are around 1/4" so if I want to use them I simply drill and ream them to fit the shaft. As Dalboy though I made some tapered ones that work well.

 

[nev]

From experience, if its rutlands, Axminster, turners retreat, timber bits, fun E turnz, and (one I cannot remember the name of in Scotland) pen kits, the different bushings available for the different kits all have the same internal size. UK Drills have a good range of cheap imperial sized drill bits for the various kits too.

 

[marcros]

i would recommend the kits from Taylors of Mirfield. You do get what you pay for, and these seem to be good quality and fairly priced for what you get.

https://taylorsmirfield.co.uk/collectio ... s-pen-kits

 

[Normancb]

In response to Dalboy's comment, I think there's a bit of mythology creeping into pen turning about over-tightening mandrel nuts. When you tighten the nut on a mandrel to lock the tubes and bushing into place for turning, you create a compression force on the bushings by putting the mandrel into tension. You can't bend a rod by stretching it, and over-tightening the nut will not bend the mandrel (though it's not a good idea for other reasons). What can bend the mandrel quite easily is applying too much pressure to the whole assembly by pushing the tailstock against the end of the mandrel too hard. That will create compressive force which can bend the whole assembly slightly. The mandrel saver works by creating compressive force on the bushings and tubes, which are held straight by the unstressed mandrel.

 

[Dalboy]

In response to Dalboy's comment, I think there's a bit of mythology creeping into pen turning about over-tightening mandrel nuts. When you tighten the nut on a mandrel to lock the tubes and bushing into place for turning, you create a compression force on the bushings by putting the mandrel into tension. You can't bend a rod by stretching it, and over-tightening the nut will not bend the mandrel (though it's not a good idea for other reasons). What can bend the mandrel quite easily is applying too much pressure to the whole assembly by pushing the tailstock against the end of the mandrel too hard. That will create compressive force which can bend the whole assembly slightly. The mandrel saver works by creating compressive force on the bushings and tubes, which are held straight by the unstressed mandrel.

Sorry I just re read my post and should have said that tightening the tailstock to tight can cause the rod to bend, well spotted

 

[woodpig]

The problem with conventional mandrels is they can often be quite long. The mandrel saver effectively reduces the length by slipping over the unused portion. The alternative would be to slide any excess through the head stock mounting each time but I'm not sure how practical it is with some designs?

 

[Dalboy]

With a two part pen I turn each piece separately therefore keeping the length to a minimum and reducing the chance of any side ways movement during turning

 

[woodpig]

Good idea.

 

[Inspector]

Or you can skip the mandrels entirely and turn between centres, either with bushings or without. You need a dead centre, the type used by metal workers with a 60 degree cone, in the headstock and a live centre in the tailstock, also with the 60 degree cone. You put the bushings into the tube ends and mount between the centres with just enough pressure to turn. There are special bushings you can buy that have matching cones machined to match the centres. The cones provide more contact surface to the centres but are not absolutely necessary. To turn without the bushings you mount the tube directly into the tubes and use vernier, dial, or digital callipers to measure as you go until you reach the size of the pen parts. Only tighten enough to drive the blank and you may need to snug it up from time to time. Over tightening will crack the blank. Turning between centres greatly reduces out of round issues you can get with mandrel turning.

A simple trick when turning between centres with regular bushings is to slow the lathe to its lowest speed and bring your fingernail slowly to the bushing. If you feel a "tapping" on the tip of your fingernail, the end of the blank isn't square to the tube at that end and needs correction. It was a trick my wife came up with when she turned pens and it cured out of roundness and ensured a good fit to the kit parts.

Pete