• Thanks for visiting The Penturners Forum today.

    There are many features and resources that currently you are unable to see or access, either because you're not yet registered, or if you're already registered, because you're not logged in.

    To gain full access to the forum, please log in or register now. Registration is completely free, it only takes a few seconds, and you can join our well established community of like-minded pen makers.

Precision Bushings

Joined
Apr 22, 2014
Posts
2,253
Location
Mirfield
First Name
Dan
OK before this goes crazy, let's clear a few things up here.
Many of you will disagree but I don't care cos I know I am right init?

The product is called a bush, bushing is what you do with it.
Unless your American in which case a tyre is a tire, burr is burl, grey is gray, and your brother is your lover, you need to be forgiven for not speaking English.
Bush's grow in the ground, bushes are machine parts, spacers / packers / shims for rotating or moving parts.

45° angle on bush is not gonna mate very well with a 60° centre, probably worse than having a hole in the end which should also be tapered to suit the mating parts.

I close with saying why should I pay extra or have especially made precision bushes? They should all be precision made from the word go, if they aren't, complain, smarten your act up and get them right to start with.
60 degree, I was only 15 out ;)

The thing I am getting at is producing a British made bushing (bush, tree, conifer) that aids turning between centres.

The mention about titanium is due to its wearing capabilities. If my engineers say they can make then then it's it worth asking the question.


Sent from my HTC One using Tapatalk
 

Phil Dart

Moderator
Executive Member
Joined
Nov 28, 2014
Posts
5,512
Location
Colebrooke, Devon
First Name
Phil
Apart from your appalling mis-use of an apostrophe, and your lack of understanding that the plural of the things that grow out of the ground is also bushes, I find myself agreeing with you Brian. Bushes should be precise, otherwise what's the point in having them. Having said that, precision costs money. So would you rather have some sloppy shite out of China for a couple of quiid, or would you rather pay a bit extra for some nice ones that fit the tubes properly and are give you the correct finished sizes?
 

rayf6604

Registered
Joined
May 1, 2014
Posts
2,726
Location
Narrowboat dweller Willington, Derby
First Name
Ray
I have turned between centres using standard bushes and the problem I have had is black dust, which I presume is carbon, that accumulates inside the bushes as result of slipping whilst turning at high speed. The dust got on my hands when I removed the bushes from the lathe and didn't notice it at first before I had touched the turned wood. I was getting black marks on the barrels staining the wood so I stopped turning between centres. Would stainless steel prevent this?

Sent from my SM-G928F using Tapatalk
 

EStreet

Registered
Joined
Jan 12, 2015
Posts
289
Location
USA
First Name
Ed
Titanium is an alloy and it contains aluminum.

Call it what you will it does not matter at all but the more you dress up a pig underneath it is still a pig. Same holds true with precision. If you don't care about quality and only produce slop then precision bushings is not right for you. Precision bushings (or what ever our wish to call them ) greatly appeals to the makers who desires the highest quality, exact part matching and demands perfection.

Bushings is both an index point and a reference point. The material used can in some cases leave marks on blanks. The word 'stainless steel' is like me saying wood blank, there are quite a hefty number of different types out there and they behave differently. Some grades are more gummy than others. The L series that I have many sets of does not that. That being said .... If you sand the bushings and add ca with out cleaning the tube then yes you will have Grey spots streaks and lines all over the blank.
 

bellringer

The Young one
Registered
Joined
Feb 27, 2013
Posts
5,187
Location
Surrey
First Name
Alex
What about case hardened bushes?

Drill bushes are case hardened and are far more resilient than stainless steel or titanium.
The only problem is the only way to machine case harden steel is to grind it which is what sand paper will do
 

Moondoggy

Full Member
Joined
Jan 2, 2015
Posts
216
Location
Lincolnshire
First Name
Paul
The only problem is the only way to machine case harden steel is to grind it which is what sand paper will do

Machine grinding is a far more aggressive process than abrasive paper. You don't get sparks flying off your bushes when you are sanding, at least I don't

Case Hardening is far harder than titanium or stainless, so you would still have the problem, it's a case (pardon the pun) of damage limitation. The only way around that is diamond or boron. Diamond bushes, that will get more women interested in turning!

The harder the material the harder it is to produce bushes from, this makes it more expensive (coupled with the greater expense of the raw material). Case hardening uses mild steel (which is easy to machine) and then it is case hardened which forms an incredibly hard skin on the item. That's is why lock shackles etc, are case hardened, have you tried cutting through one of those? Doable, but not easy.

You need to investigate hardness figures (Rockwell, Brunell, Vickers etc.) for the various materials and make an informed decision based on that harder the finished bush, the longer it will last.

Dan, the best process (IMHO)for making bushes would be: -
Using Bright Mild Steel
Face off bar
Drill hole
Ream hole
Turn outside diameters.
Part off
Grind outside diameters
Case harden

Result, precision, longer lasting bush.
More expensive, but they will last a long time.

That is how we would have done it in the aircraft industry toolmaking department where I worked for a number of years.:thumbs:
 

Penpal

Grand Master
Joined
May 26, 2013
Posts
25,342
Location
Canberra AUSTRALIA
First Name
Peter
Is this discussion heading to no mandrel turning there is no such thing as a dual purpose precision set when it refers to mandrels unless decent accurate mandrels are used. When talking about hard as bushes they will cause bother with centres both live and dead centres.Personally I dont sand the living daylights of the bushes I use they are made undersize and I measure the finished sizes. Anyone using mandrel savers will need to match their mandrel saver with the proper sized mandrel.

The worst problem used to be brass bushes the carry over of finishing products that reacted with the brass. Enjoying the semantics with word bushes.Meaningless really.

Peter.
 

billyb_imp

Registered
Joined
Mar 2, 2014
Posts
4,298
Location
Lincoln, UK
First Name
Billy
Not to bothered about bush's specifically for turning between centres, we can do that with the ones we are already using, like others have said we need the precision from the start and it would be great if they were harder wearing
 

silver

General dogsbody
Executive Member
Joined
Jun 29, 2013
Posts
6,304
Location
Somewhere in Staffordshire,
First Name
Eamonn.
I Know I am right
I can't argue with experience mate...

Machine grinding is a far more aggressive process than abrasive paper. You don't get sparks flying off your bushes when you are sanding, at least I don't

Case Hardening is far harder than titanium or stainless, so you would still have the problem, it's a case (pardon the pun) of damage limitation. The only way around that is diamond or boron. Diamond bushes, that will get more women interested in turning!

The harder the material the harder it is to produce bushes from, this makes it more expensive (coupled with the greater expense of the raw material). Case hardening uses mild steel (which is easy to machine) and then it is case hardened which forms an incredibly hard skin on the item. That's is why lock shackles etc, are case hardened, have you tried cutting through one of those? Doable, but not easy.

You need to investigate hardness figures (Rockwell, Brunell, Vickers etc.) for the various materials and make an informed decision based on that harder the finished bush, the longer it will last.

Dan, the best process (IMHO)for making bushes would be: -
Using Bright Mild Steel
Face off bar
Drill hole
Ream hole
Turn outside diameters.
Part off
Grind outside diameters
Case harden

Result, precision, longer lasting bush.
More expensive, but they will last a long time.

That is how we would have done it in the aircraft industry toolmaking department where I worked for a number of years.:thumbs:

I couldn't agree more..

As ED states I would avoid Ti.

One to watch out for is the differences in material specs from over the pond is very different to the UK. (You guys seem to have your own lingo for everything) stainless steel? What grade? 304, 310 or 314, the higher the number the higher chrome content. Greater heat resistance, wear and resistant to oxidisation.

After turning lens for many years I have made my pens "with precision" using home made bushes for turning between centres as well as for Mandrels.

I personally don't see the need for them and just see it as another "fad" having said that if there is a custom base then jump on the band wagon and make hay while the sun shines Dan.

Whatever your customer base wants then go with it.
 

Gizmo3k

Graduate Member
Joined
Sep 8, 2014
Posts
616
Location
Armadale, West Lothian
First Name
Alan
I turn my pens between centres, usually without bushes. The times I have used bushes, I usually end up with an out-of-round pen, either because the hole in the bush isn't properly centred, or the bush is rocking on my live/dead centre (I don't know which). If I could get a hold of some bushes that were definitely accurate, I would probably use them for rough sizing, then sand and measure the last little bit.

I would probably be interested in trying some accurate bushes which are meant to fit my centres though!
 

Grump

Grand Master
Joined
Aug 17, 2013
Posts
10,510
Location
Stevenage
First Name
Brian
Interesting thread with some valid points and opiions.
I need to gob off again init?

My appalling mis-use of an apostrophe, was not my use at all, simply repeated, read the thread.

It don't matter what material you use you will only ever achieve precision by making bushes to fit each pen as a one off.
There is so much fluctuation between the tubes from one to another of the same batch, it don't matter how precise the bushes are if the tube don't fit on em init?
You would get more precision by not using bushes and turning directly in the tube.
 

Phil Dart

Moderator
Executive Member
Joined
Nov 28, 2014
Posts
5,512
Location
Colebrooke, Devon
First Name
Phil
Yes, there are many instance's of appalling mis-use's of apostrophie's. Don't think I was picking on you. It(')s everyone else.

So its precision tubes we need as well as bushes. Couldn't agree more. And a standardised mandrel shaft wouldn't go amiss either.
 

Penpal

Grand Master
Joined
May 26, 2013
Posts
25,342
Location
Canberra AUSTRALIA
First Name
Peter
I did not join the forum for English lessons since most contributions make fundamental errors that are meaningless to me what matters is content this subject touches on every member on the forum in the way mandrels , bushes and tubes are made. For ever I have used a go no go guage to measure tubes since this is fundamental and I discard tight tubes only rely on bushes as spacers, mandrels as varying, I match my precision made Mandrel savers to actual in use mandrels. For Dan to tackle a basic essential for penmaking could be a vital step forward for too long near enough has been accepted by manufacturers and some dealers, full marks best wishes Dan.

Peter.
 

Grump

Grand Master
Joined
Aug 17, 2013
Posts
10,510
Location
Stevenage
First Name
Brian
So its precision tubes we need as well as bushes. Couldn't agree more. And a standardised mandrel shaft wouldn't go amiss either.

If there was some quality control in the manufacture and things were made to fit we wouldn't be having this debate or the need to ask the question.

I appreciate that we all have to work to a plus / minus tolerance but those tolerances can be reduced with a bit of thought.

Another point I would like to raise and one which once again will be disagreed with, I dunno about anyone else but I treat bushes as consumables.

For me they are sacrificial and only there as a guide and to hold the rig together, I certainly wouldn't rely on them as a true measurement.
They are easily and quickly made in my choice of material so have no need to be a sloppy fit nor expensive.

Something else that cropped up in my shed during the week, while drilling on the lathe I noticed the drill bit was wavering very slightly at finding centre.
I checked kiss and all was fine, could feel no lateral movement on the spindle and the tapers were clean, put my dial gauge inside the spindle and registered 0.4 movement when pushed upwards.
Not a lot and perfectly acceptable to some but I had only replaced these bearings with expensive ones a few months ago so for me not good enuf init?
I put a dead centre in taper to get a tad more leverage and expected that to be round, far from it.
I ended up machining most of my centres including a new unused steb which was the worst one.
I am guilty of taking for granted that these things are fit for use from the box.
SKF will be getting their bearings back with a few choice words from me very soon, although I couldn't push it out far when it had a lump on and started spinning it very soon became exaggerated.

Yes it's a crap Charnwood lathe but it was accurate a few months ago and I expect it to be now, my little Chinese metal lathe makes a better dead centre than the ones I paid money for.
We are discussing precision here and I am finding I can't buy it whether that be in a cheap tool or a trusted name.
 

EStreet

Registered
Joined
Jan 12, 2015
Posts
289
Location
USA
First Name
Ed
I really feel bad for Grump on this topic.

Ok maybe not. Grump, FYI there is a thing called class of fit. Look it up in the machinist handbook. Class of fit is the quality of fit be it super loose to you must press it in. The range is very large.

Precise would be where you are unable to feel the edge of either metal part or blank where they union. It becomes almost trivial do this when you bushings are very precise.
 

bellringer

The Young one
Registered
Joined
Feb 27, 2013
Posts
5,187
Location
Surrey
First Name
Alex
My view on this is that the bushings should be manufactured on the two OD's the tolerance should be .01+- and the hole should be reamed to 6.23 which is what I have found to be a rough standard size the mandrel rod should have a tolerance of +.00 -.005 these tolerances are 100% achievable and would make ever thing fit nicely if Taiwan say they can not achieve these tolerances then I say bring the manufacturing home again yes ok it might cost a couple of pence more but who cares


Sent from my iPad using Tapatalk
 

Grump

Grand Master
Joined
Aug 17, 2013
Posts
10,510
Location
Stevenage
First Name
Brian
I really feel bad for Grump on this topic.

Ok maybe not. Grump, FYI there is a thing called class of fit. Look it up in the machinist handbook. Class of fit is the quality of fit be it super loose to you must press it in. The range is very large.

Precise would be where you are unable to feel the edge of either metal part or blank where they union. It becomes almost trivial do this when you bushings are very precise.

Certainly no need to feel bad for me, I can make my own when I need them, and make them to fit.
I have not had a problem I can't get over or around.
My point is, there should be no need for an option of precision fit.
The bloody things should fit from the off, it's what your order, pay for and expect to receive.
Like I said in my first post, I don't care, I don't care who I upset, I don't care about bushes and I don't care how much you pay for the things, I don't buy them.
I haven't bought a kit nor bushes for ages and don't intend to until I see some improvement, I see a load of talk but nothing substantiated.
 
Warning! This thread has not had any replies for over a year. You are welcome to post a reply here, but it might be better to start a new thread (and maybe include a link to this one if you need to).
Top