Types of Boring bar

[13SigsParticipant @13sigs]

[13SigsParticipant @13sigs]

I need to buy a boring bar in order to enlarge a 20mm, through hole, in a section of mild steel and some brass spacers. My lather takes 10mm tools and I was about to buy a Glanze boring bar with carbide tip when I was asked did I want a boring bar for through holes, or for holes up to a shoulder (blind).

How do I ensure that I am supplied with the correct type of boring bar? I will be grateful for any advice.

Thanks.

[JasonBModerator @jasonb]

I would go with their SCLCR type holders as they will do both which will be more use in the future. Same type on the Glanze site

Edited By JasonB on 05/05/2014 17:05:15

[Oompa LumpaParticipant @oompalumpa34302]

You can also get boring bars for internal backgrooving. I have just bought one of these in 6mm ISCAR Need to find some tips now at a reasonable price, reasonable being relative of course

graham.

[Ian S CParticipant @iansc]

13Sigs, Tomorrow I'll be boring a 35 mm bore in cast iron for the power cylinder of a hot air engine, I'll be using a home made boring bar with a HSS tool made from a broken 1/4" centre drill, this set up is ok for anything from aluminium, to stainless steel. Ian S C

[13SigsParticipant @13sigs]

Posted by JasonB on 05/05/2014 17:02:38:

I would go with their SCLCR type holders as they will do both which will be more use in the future. Same type on the Glanze site

Edited By JasonB on 05/05/2014 17:05:15

Thanks. I will do just that.

[Ian S CParticipant @iansc]

Cylinder bored, the bar I used has a bit of 1/4"sq HSS, I made it before I had got round to breaking centre drills, so I filed a square hole through the bar which is 3/4" dia x 6" long. Ian S C

[NobbyParticipant @nobby]

Hi
You have not said the depth /deep you want to go as you could use a 3/8" / 10 mm HSS ground to suit
Nobby

[13SigsParticipant @13sigs]

Posted by Nobby on 07/05/2014 12:34:19:

Hi
You have not said the depth /deep you want to go as you could use a 3/8" / 10 mm HSS ground to suit
Nobby

Edited By Nobby on 07/05/2014 12:34:37

The through hole has to be enlarged from 20mm to 25.4mm (inch) for a length of 43mm. The individual spacers will be worked on seperately, they are packing and are 3mm and 5mm thick. A picture of what is suggested will be a great help.

[Neil WyattModerator @neilwyatt]

An HSS rod ground away just OVER half way (not just less as with a d-bit) and mounted with the end level and angled slightly towards the operator will do the job as Nobby suggests. Stone the point on the corner making sure to maintain relief below the cutting edge so it cuts, not rubs.

Neil

[13SigsParticipant @13sigs]

Posted by Neil Wyatt on 07/05/2014 19:08:27:

An HSS rod ground away just OVER half way (not just less as with a d-bit) and mounted with the end level and angled slightly towards the operator will do the job as Nobby suggests. Stone the point on the corner making sure to maintain relief below the cutting edge so it cuts, not rubs.

Neil

Thanks. This is the Beginners site, and, there is no better begining beginner than me. However, the help on this website is taking the incline out of the previously very steep learning curve. Would it please be possible to include a photo of what the finished item will look like. I understand that the main shank of the tool will have to be a smaller diameter than the cutting tip but what form the d-bit is, has me foxed. in addition, I presume a round bar will have to be mounted in a bar holder, or have flats ground along the diameter. My machine takes 10mm tools. I have a grind stone and the tool to dress the stone in order to maintain a true surface.

Not only but also, what I need is to gain some of the knowledge that comes second nature to those who have been at this for years. For example, yesterday I was told how to use parallel bars to position the face of a piece of work square in the jaws of a chuck. Easy when you know how, but the how is the difficult bit.

[Ian S CParticipant @iansc]

A quick and simple boring bar, take say a half inch drill bit, clamp it in the tool rest pointed at the chuck, now angle the tip slightly towards you and get the corner of the lip of the cutting edge at centre hight— boring bar.

Ian S C

[Neil WyattModerator @neilwyatt]

Hi 13,

No it's simpler than that. You literally grind away just over half the HSS rod for a short distance (say 10mm) back from the tip. You can grind the end back at a slight angle to give a bit of relief, but don't touch the shank.

Fit in the toolholder just as Ian describes.

Take a look at my album HERE

In the photo below the one on the left is from silver steel .hardened and tempered, and the one on the right is HSS, just ground.

Neil

[John McNamaraParticipant @johnmcnamara74883]

Hi 13Sigs

Some time ago I tried using these fairly inexpensive Asian boring bars for boring in the lathe. I had a set at hand to use with my boring head in the mill.

I tried one out as a boring bar in the lathe and it worked quite well. Now for smaller work I use them all the time, They are easy to sharpen with a diamond wheel. Diamond wheels also are now reasonably priced.

You may need to remove the sharp corner under the cutting edge to provide more relief to avoid rubbing if boring small holes.

When using them choose the shortest and stoutest size for the work at hand, reducing overhang and a thick stiff boring bar is always the best way to go to avoid chatter and get a good finish. Drill a pilot hole to start as big as practicable to start, The heavier ones will take quite a heavy cut if your lathe can handle the power and there is clearance for the chips.

Here is a link to a post I made on this site on how to make a holder; you can adapt it to the size of your tool holder:
**LINK**

Bar Set:
**LINK**

Boring Bar Images:
**LINK**

Regards
John

[Neil LickfoldParticipant @neillickfold44316]

There are a new generation of boring bars that have vibration dampening technology. Some have a carbide or some other heavy metal that vibrates and counteracts the vibration from the tool. Another one in the small bar sizes is the Dynamic series from Kyocera, or the Dimple series from Mitsubishi.They make them in steel and carbide shanks. Carbide costs a lot more but has a lot longer diameter to length ratio.

After using the vibration dampened tools, you will not want to use standard tools again.

I have made dampened tools to external turning for tools that needed to have along over hang.

To test the effectiveness of the tool in making it , I tap the side of the tool and if it does not ring, it will be fine.

In the small bars I like the ones with a sort of triangular shape that allows 3 cutting edges instead of the 2.

Neil

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