Boring for a Beginner

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Boring for a Beginner

This topic has 48 replies, 15 voices, and was last updated 30 March 2010 at 22:35 by mgj.

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21 March 2010 at 16:43 #49985
Richard Stacey
Participant
@richardstacey70920
I am very new to model engineering and as my first project I am attempting the Stuart S50 Mill Engine using the Tubal Cain “Sally” articles as my guide. I have a factory reconditioned Myford 10 and a small Chester Milling Machine. To date I have almost completed the bedplate and looking ahead both the next items Flywheel and Cylinder involve the use of boring tools of fairly small size. I have not been able to source these but have seen 3/8″ boring bars + holder using 1/8″ square section HSS toolsteel (which I assume must be ground to a suitable profile.

Would this be a good route to take for a complete beginner or is there a better option – any advice would be much appreciated – many thanks.
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21 March 2010 at 16:43 #5009
Richard Stacey
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@richardstacey70920
21 March 2010 at 17:21 #49988
JasonB
Moderator
@jasonb
You should be able to get (or make) a similar tool that has a 1/4″ holder and still uses the 1/8″ HSS bits I used a cheap set of 4 boring bars like this for a number of years. Always use the largest dia bar possible and as you get near the finished bore run the tool through several times without putting on any more cut as there will be some spring in the tool that needs working out.

I think my set came from Tracy Tools but Warco do one

The other option is one of the small indexable boring bars but I woul dstick with the others for now. For the flywheel you could also use a reamer.

Jason

Edited By JasonB on 21/03/2010 17:25:43
21 March 2010 at 17:33 #49989
macmarch
Participant
@macmarch
You can also make some boring bars from various diameters. Cross drill 1/8″, 1/4″ 5/16″ to take round toolbits. This makes it easy to adjust the cutting angle for different materials. Drill one end at right angles and the other at 45Deg. Oh forgot, the toolbits are ground from your broken centre drills.
21 March 2010 at 19:59 #49992
Richard Stacey
Participant
@richardstacey70920
Many thanks Jason, I’ll have a look at Warco for a set of boring bars.

Richard
21 March 2010 at 20:01 #49993
Richard Stacey
Participant
@richardstacey70920
Many thanks for the tips about making up my own boring bars and using up broken drills – I’ll be sure to give it a go.

Richard
21 March 2010 at 20:59 #49994
Nigel McBurney 1
Participant
@nigelmcburney1
Hi to make good boring bars use silver steel, then cross drill a hole to take the tool bit,secure with a socket head grub screw. If you ream the flywheel as suggested above,start as usual by facing the boss of the casting then centre drill, drill through at least 1.3 mm undersize then bore to within 0.25 mm and then ream,use a machine reamer which is parallel for its full length. using this method will keep the hole running true.Hand reamers have a long tapered lead and are meant for hand reaming tight holes,machine reamers produce a better bore. Be careful about buying reamers ,there are a lot on the used market in dealers,boot sales and bring and buys,many are ok but some may have come from factory stores and have been ground to special size,sometimes they are only reduced by .1 or .2 of a mm,sometimes there is a number engraved on the shank which is a tool number indicating a special size. To get the best results,use toolmaking practice and grind a round or square HSS toolbit into a boring bar, the toolbit steel is tough and very rigid,lot of grinding but its worth it.
21 March 2010 at 22:00 #49999
mgj
Participant
@mgj
Chronos do a very good set of boring bars. I only found out about them because they came with a boring head I bought. 1/2″ shanks various lengths. Its a slightly unusual design which I hadn’t seen before, though maybe others have. To re-sharpen you only have to touch up one (the top )face which is very handy.All the other reliefs are built in.

I’ve been using them out of the boring head in a separate holder, and they work very well.

Whether they are better than knocking up a bar out of bar and grinding up a 1/4 bit (or better 3/16 bit for a smaller lathe) I don’t know, but they are a lot more convenient to sharpen and set!

Edited By meyrick griffith-jones on 21/03/2010 22:09:36
21 March 2010 at 23:19 #50001
russell
Participant
@russell
can anyone point to an illustration of ‘how’ to grind a bit for a boring bar?

I made a simple bar, drilled 1/4 about 45 degrees (so the bit projects beyond the end of the bar) – i started with the end of a 1/4 drill, ground (using the ‘diamond tool holder grinding jig). It sort of works, but clearly the end of this particular drill bit is soft (i know because i cut it with a hacksaw…).

Can HSS be hardened?

thanks
22 March 2010 at 08:59 #50005
mgj
Participant
@mgj
Russel – you used the wrong end of the drill- the shank will be soft.

Can HSS hardened. Yes, but not by amateurs.

Going into how to grind a bit is a bit long for a post like this. Tubal Cain, the Model Engineers Handbook lists all the angles and shapes you will need. Basically you just grind a standard knife tool onto a piece of 1/4″ tool steel, but you have to add 45 to everything, apart from the top face.

I am afraid the diamond tool holder wont work because that’s designed for a 12/12 deg set up.

I would suggest one of two options:

1. If terms like side clearance and back rake mean nothing to you then TC’s book will explain, and then you can grind any bit on your own. (You will have to learn at some stage, and at some stage you will probably end up making some sort of tool grinding jig or rest)

2. If you don’t want to buy the Model engineers handbook (unwise!) then buy a carbide indexable tipped bar. Pain free, easy , good results (at a price). Its also a very good choice for the person who may not be up to speed on his angles, but needs to cut metal effectively when making his grinding holder!

I know people moan about carbide, sometimes finish and sometimes about being brittle. The fact is that when they do so they never specify what grade they used in which application, and they overlook the fact that 90% of the world are getting excellent results using it interchangeably with HSS at HSS cutting rates. So they should be asking themselves what they are doing wrong, not complaining that everyone else isn’t right!

On which note I will say that twice I bought unbranded cheap tips. Never ever again. They were brittle, and wore very quickly and the coating was rubbish. Decent branded tips, always, and they work brilliantly in a variety of materials. (HSS cutting speeds and feeds because that’s how I like to work, loads of coolant, and its difficult to go wrong)

Edited By meyrick griffith-jones on 22/03/2010 09:06:34
22 March 2010 at 09:26 #50008
KWIL
Participant
@kwil
The advantage also of decent coated branded tips is that you can also use them dry, without coolant. Just try to keep to the correct grade for the material being cut.
22 March 2010 at 11:07 #50015
Ian S C
Participant
@iansc
Some times you can use ordenary drills if they breaknear the top of the fluted part were it’s hard. Broken center drills, broken or warn out taps,are a source of HSS. For small boring bars I braze tips removed from old circular saw blades onto bars made from 8.8 strenght bolts, the tips I use are about 2mm square x 4mm long, you can make external tools with the same tips. Ian S C
22 March 2010 at 11:10 #50016
JasonB
Moderator
@jasonb
The only thing to watch if you want to by an indexable holder for the flywheel is the minimum size hole, even with something like the mini bar that chronos do you will not have the length to do the 3/4″ long bore!! as the small dia means you can’t use a larger diameter and hence longer bar.

Russel, have a look at the reprinted Sally articles about the S50, first one shows how to grind suitable tools.

Jason

Edited By JasonB on 22/03/2010 11:11:55
22 March 2010 at 11:33 #50019
russell
Participant
@russell
thanks meyrick, i have the book, and have ground bits before, not as well as the tangential jig does them though ( my elderly drummond B type lathe needs all the help it can get!)

.

The tip about ‘knife’ tool is what i need to get started. still getting my head into thinking about all the angles rotated 45deg. (and of course the boring bar itself can be rotated).

then i just need to map it onto the broken stub of the drill ( the next bit up has some flutes on it, so should be hard).

my thought (hope?) is that i can take the ‘tangential’ idea and find a single grind angle (or maybe 2?) and end up with a repeatable jig.

i’m working my way through the back issues of MEW. , and i have the last 30 odd years of ME plus some odd older ones. just need a good index!

regards, and thanks.

russell

Edited By russell on 22/03/2010 11:45:23
22 March 2010 at 11:35 #50020
russell
Participant
@russell
jason, thanks for the tip about ‘sally’, i printed it out but havent read it yet.

i am using this hot air engine as practice before i start on a casting set for ‘pevensey’ a local (Oz) horizontal engine.

regards

russell
22 March 2010 at 13:02 #50023
mgj
Participant
@mgj
I have been a bit thick, because its a very small hole.

Leaving aside what we said about boring bars, I don’t think I’d bore it at all.

Knock up a d bit or use a reamer after drilling. Set to edge, drill and ream. Then mount rough flywheel on mandrel off the bore, and machine rim etc. That way the inside edge of the rim will seem to run true for appearances sake, and the whole thing will be concentric with the mandrel if mounted in 4 jaw or collet, so it will balance and run properly. .

Avoids grovelling around in the bottom of very small holes.

Sorry – should have thought.

Won’t get you away from boring bars in the end, but that would possibly be an easy way for this job.
22 March 2010 at 16:18 #50031
JasonB
Moderator
@jasonb
I see in the latest issue there is now a UK suppier for the Pevensey and the other engines from MSM though they do look a lot like stuart designs

Jason
22 March 2010 at 17:19 #50032
Richard Stacey
Participant
@richardstacey70920
Many thanks to all who replied to my thread, I have ordered a set of small boring bars from Warco and The Model Engineers Handbook (Tubal Cain) and I intend to have a go and grinding the bits myself as I know that grinding tools is a skill I shall need to learn.

Richard
22 March 2010 at 18:06 #50033
chris stephens
Participant
@chrisstephens63393
Hi Richard,

With regard to boring , there is not much to be said on the subject in ME’s Handbook by ‘Tubal Cain’, but if you were to buy GHT’s book “The Model Engineer’s Workshop Manuel” you would find, in the chapter entitled “Boring Tools”, much useful information.

He does not mention indexable boring tools, perhaps it it time for the publishers to put a few updates in future editions, but the basic details still hold true.

The model Engineers Workshop Manuel is not for nothing nick-named the Model Engineer’s “bible”, granted it is over 25 years since first published and the original articles somewhat older than that, it’s information is still valid for “our” end of the ‘learning curve’.

chriStephens
22 March 2010 at 19:50 #50034
Richard Stacey
Participant
@richardstacey70920
Hi Chris,

Many thanks. I’ll take a look at The Model Engineers Workshop Manual but like many my budget is beginning to run away with me!!!

Regards

Richard
23 March 2010 at 00:01 #50037
chris stephens
Participant
@chrisstephens63393
Hi Richard,

I’m not going to be stupid enough to say it is the only book you will need, but it one of the few books that really will teach you a workable method for a lot of things ME. Some books are, I feel, written by those who are more interested in “vanity publishing” and just re-hash the work of others without gaining the experience that is needed for proper teaching. But Hey Ho, life goes on!

Re the budget deficit, you had better get used to it, it gets worse as you go along. There is always another bit of kit that you ‘need’, then you ‘need’ a bigger workshop to replace the shed you built to replace working on the kitchen table, where you started your fascinating journey into bankruptcy.

chriStephens
23 March 2010 at 08:19 #50040
Ian S C
Participant
@iansc
Try using the Library, if your library is half as good as the ones on this side of the planet you’ll find just about anything you need, and usually if they don’t have it they’ll get it. Ian S C
23 March 2010 at 09:44 #50043
Richard Stacey
Participant
@richardstacey70920
Hi Chris,

I have ordered the Tubal Cain book from Amazon and at only £6 it wasn’t too painful. I already have a couple of other books by TC (Drills, Taps and Dies + Soldering/Brazing) and I am building my first steam engine based on his articles. I have found all of his advice relatively easy to understand and his methods practical in my small and limited workshop.

Regards

Richard
23 March 2010 at 12:49 #50052
chris stephens
Participant
@chrisstephens63393
Good choices, but any instructional book by Tubal Cain is worth reading, he is an author with the ability and experience to back up his teachings. When you can afford it buy some more of his, but I still think the GHT book worth having, sooner rather than later.

Your workshop may be “small”, but lets be optimistic and call it “compact”, but lets not say “limited” the only limit is human imagination, which as we know is limitless.

As a generalisation, more or better equipment makes making things easier, but poor or lack of equipment does not stop the motivated from succeeding. Look at the people who made steam engines with little more than a drill and a hammer.

chriStephens
23 March 2010 at 16:57 #50062
Terryd
Participant
@terryd72465
Posted by russell on 22/03/2010 11:33:18:

…………………

i’m working my way through the back issues of MEW. , and i have the last 30 odd years of ME plus some odd older ones. just need a good index!

regards, and thanks.

russell

Edited By russell on 22/03/2010 11:45:23

Hi Rusell,

there is a good index of ME and MEW articles on the net Here:

http://www.itech.net.au/modelengineer/ 

Best regards

Terry
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