Precision Bushings

[Bob Ellis]

To answer Phil's question directly, I have a set of Axminster bushes and the inside diameter of all three in 6.20mm +/- 0.02mm.

 

[bellringer]

There is only one to get them 100% true this come from the experience of manufacturing part for old bugatti engines if you want the this way you need to gun drill the hole leaving a mirror finish the place the bushing on to a precision made mandrel and either grind or turn bettween centers you will end up with it been 100% true then the run out should be tested but that would be extreme way of doing it

With case hardning you really need to grind them after hardning to take in to account any Stress (can't think of the right word). I think it best to use 316 stainless steel and have them made in one operation rough the od then spot drill the hole then drill and ream then finish turn then do a part transfer to the sub spindle then finish turn the face and chamfer the hole once made they should be test for any run out if there is any the spindle are out of alignment

 

[bellringer]

Just developing this a bit further, does anyone here own any bushes from axminster? If you have a set of verniers, what is their i/d please, and if you have more than one set, are they all the same I wonder.

The hole in the Axminster once are drilled and will never be any good

 

[Neil Lawton]

So what's going on here then......

Just checked.

New lathe is fitted with the Evolution mandrel and saver.
I have a planet mandrel, and another of unknown make which Walter gave me. Neither will go into the Evolution saver as they are a larger diameter, and as such the Evolution bushes will not fit on them either.

Now here's the rub! The last few pens have been made on the Evolution mandrel, but with bushes that do fit on the planet one. Surely they should have been wobbling about all over the place?
Well they didn't, and there was no problem with the turning or finishing, and the pens are perfectly round!

Am I not throwing the chisel at the wood hard enough?

 

[Penpal]

Dan what does your Engineer mate have to say on Bushes and Mandrels or between centre turning of pens? I feel you have kicked over the bees nest in good faith and not be exposed to undue stress.

Peter.

 

[TaylorsMirfield.co.uk]

Dan what does your Engineer mate have to say on Bushes and Mandrels or between centre turning of pens? I feel you have kicked over the bees nest in good faith and not be exposed to undue stress.

Peter.

My engineer has no previous experience on pen making. He specializes in aerospace component's.
The key part of my project is his 5 axis CNC machine. I am confident he can make most things out of steel.
I am curtain he can make high precision components for me but attempting to offer an improved mandrel/bushing may just add to the concussion over compatibility.

Sent from my SM-N9200 using Tapatalk

 

[Terry]

I assume Dan that the bushes you will get made are for your TM pens and possibly Phil's only and not for 90% of the rubbish that is out there. As your pens and Phil's Mistral are upmarket pens then surely you can have your tubes specified to a certain tolerance which should be honoured by whoever makes your kits. If that is the case then you could have mandrels specified to the same tolerance and also the bushes. As most turners use a mandrel saver then as long as your mandrel fits the saver with a close tolerance then the majority of the turners on this forum will be winners as they already buy your kits rather than kits from other suppliers.
As Woody says even if the bushes wear out then just replace them because at the end of the day a set of bushes are about the same price as a cup of coffee.
I would say go ahead with this idea and keep up the good work as I think you are on to a winner !!!

 

[bellringer]

The problem with tube is it extruded and the tolerance is low

 

[Penpal]

How revealing the deeper we go into the basics of penmaking how important pricing becomes to acheive Fair Average Quality in mass production. Almost immediate questions are emmachisit. I sought in the USA, here in Australia to get a simple step drill ground in tool steel what a farce the attempts and results were ugly the claims extraordinary from Europe reasonable but the crunch was all you could buy thirty years ago to face a blank, lightly ream the brass was this simple unit I still use for every Slim type pen. If you think I was interested in your project well I am. My step drill cost 20.00 AU so many years ago worth its weight in precious metal IMHO.

I will follow this all the way through Dan.

Peter.

 

[Penpal]

The problem with tube is it extruded and the tolerance is low

So very true in some countries made on the street.

Peter.

 

[Penpal]

The problem with tube is it extruded and the tolerance is low

So very true in some countries made on the street.

Peter.

Sorry my computer seems to get hiccups.