# Line boring bar idea



## xander janssen (Sep 11, 2020)

Hi all,

After building several Stirling engines and Jan Ridders (like) IC engine, I'm thinking of designing my own 2 or 3 or 4 cylinder IC engine loosely based on the appearance of the BruceMacBeth engine.

Idea is to use a build cranckshaft with oversized journals that include ball-bearings like: German example of a build crankshaft

This because I tried this technique before and its construction works well with the machines (lathe, mill) that I have. Whereas fully turned or brazed crankshafts never turned out very well.

To incorporate this crankshaft, I need to perform a line-boring operation on the crankhousing made from aluminum. 

I would like to get you opnion on the following idea for a line boring bar that can be used on the lathe between centers, with the crankcasing situated on the carriage.

Diameter of the bar: 30 mm
Diameter of final bore: 37 mm


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## ICEpeter (Sep 11, 2020)

Hello Xander,
I have made such a line boring bar myself a while ago for the same purpose for use between centers in a lathe. Myford in the UK I believe has them as well as an accessory for sale. Making one is not too difficult provided you have or have access to a square reamer of the size of your cutting insert.
I suggest to google "line boring bar" and you will get some hits.

Peter J.


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## xander janssen (Sep 11, 2020)

I do not have a square broach. That is why I want to use a round toolbit with a flat on it. I hope this will work well for very light cuts.


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## ICEpeter (Sep 11, 2020)

xander janssen said:


> I do not have a square broach. That is why I want to use a round toolbit with a flat on it. I hope this will work well for very light cuts.



If you do not have a square broach, do it the old fashion way and file the round hole square to fit the size of your tool bit which I assume, based on the diameter of your bar, could be 3/16 or 1/4 inch which would accommodate filing a square hole quite easily.
Since you provide your dimensions in Millimeters, are you located in Europe somewhere or elsewhere?

Peter J.


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## Jasonb (Sep 11, 2020)

Should work fine, I've a couple like that. Another option with the tool bit is to drill a hole to suit the across corners size of say 3/16 or 1/4 square toolsteel. I mostly just use round HSS though. The bar in these videos is 28mm so not far off your proposed size


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## BaronJ (Sep 11, 2020)

Jasonb said:


> Should work fine, I've a couple like that. Another option with the tool bit is to drill a hole to suit the across corners size of say 3/16 or 1/4 square toolsteel. I mostly just use round HSS though. The bar in these videos is 28mm so not far off your proposed size




Yes, that is what I do as well, a round hole and a pinch screw.  Even using round HSS I grind a flat for the pinch screw to bite onto.

One dodge that I also use is a grub screw underneath to push the tool bit out a bit.  Which also allows you to use a mic to set the amount of cut.


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## xander janssen (Sep 11, 2020)

Thanks for your replies. Make me more confident to give it a try.

Indeed, I live in Europe. Belgium to be more precise. Pretty used to the metric system indeed


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## SmithDoor (Sep 11, 2020)

I just ground stock or O1 or W1 drill rod 
The drill a hole for cutting tool and drill & tap to hold the cutting tool.
You buy round tool bits or use a old end mill.

Dave



xander janssen said:


> Thanks for your replies. Make me more confident to give it a try.
> 
> Indeed, I live in Europe. Belgium to be more precise. Pretty used to the metric system indeed


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## tonyr769 (Sep 12, 2020)

You can use an old tool making dodge to make a square  hole. Drill a hole just on size and file it out nearly to the square size. Then grind the hss tool bit square at the ends. One end with sharp corners. Then tap the hss tool through the hole similar to a broach. When a burr is raised at the working edge gently file burr down and tap drift through again. You can get a very accurate and secure square hole this way. Take care and use safety glasses as the hss tool  bit may shatter if hit too hard. I would then use a new bit for cutting as cracks may have been introduced to the working bit.
May be of use.

Tony


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## BaronJ (Sep 12, 2020)

tonyr769 said:


> You can use an old tool making dodge to make a square  hole. Drill a hole just on size and file it out nearly to the square size. Then grind the hss tool bit square at the ends. One end with sharp corners. Then tap the hss tool through the hole similar to a broach. When a burr is raised at the working edge gently file burr down and tap drift through again. You can get a very accurate and secure square hole this way. Take care and use safety glasses as the hss tool  bit may shatter if hit too hard. I would then use a new bit for cutting as cracks may have been introduced to the working bit.
> May be of use.
> 
> Tony


Hi Tony,
Have a look at this thread,





						Cutter grinder
					

I have the whole machine in my shop and it's become my best friend.  I purchased it a tool auction probably 12 years ago or so.  It only took me10 years more to learn how to use it properly from the translated from the Chinese manual that came with it.  I subscribe to a forum called The Tool and...




					www.homemodelenginemachinist.com


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## tonyr769 (Sep 12, 2020)

BaronJ said:


> Hi Tony,
> Have a look at this thread,
> 
> 
> ...



Hi Baron,

I thought that was an ingenious idea for cutting a key slot. The method I mentioned is used for a hole at right angles to the boring bar.

Tony


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## deverett (Sep 12, 2020)

If you enjoy tool making, you might like to copy G.H. Thomas' between centre boring bar design.
Basically, he uses a round toolbit set over at 45 deg and uses a 40 tpi screw to advance it.  A lock screw prevents unwanted movement.
I can send you details if you would like.

Dave
The Emerald Isle


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## goldstar31 (Sep 12, 2020)

Dave
           Might I add a small correction?  The angle to compensate is actually 40 degrees which gives an amost correct cut using 40TPI.

Well that is what I made when boring the two bed bars on the Mark1 Quorn tool and cutter grinder which has to hit 1.000" on the castings apart from one at 1.003" if one is not using split cotters 'wot I did'

Best wishes. Great book for £30-ish

Norman


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## ignator (Sep 12, 2020)

There's a youtube channel I watch, a repair machinist, that shows the making of a large line boring bar that may be of interest to his technique and usage:
3 part series


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## BaronJ (Sep 12, 2020)

tonyr769 said:


> Hi Baron,
> 
> I thought that was an ingenious idea for cutting a key slot. The method I mentioned is used for a hole at right angles to the boring bar.
> 
> Tony



Hi Tony
Thanks for your comments.

You could use exactly the same Idea on a round, square or rectangular bar to make a square hole through it.  My broach will work just as well using a square section as it will in a between centers line boring bar to produce a round hole.

Obviously it gets harder as things get smaller, my original key slot cutter was for a 4 mm keyway in steel pulleys.


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## tonyr769 (Sep 13, 2020)

deverett said:


> If you enjoy tool making, you might like to copy G.H. Thomas' between centre boring bar design.
> Basically, he uses a round toolbit set over at 45 deg and uses a 40 tpi screw to advance it.  A lock screw prevents unwanted movement.
> I can send you details if you would like
> Dave
> The Emerald Isle


Hi Dave

Not sure if your message was for me or the author. Anyway I personally do enjoy tool making having trained as a press tool tool maker. Thanks for your offer but G H Thomas' book is on my Christmas wish list.

Thanks
Tony


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## goldstar31 (Sep 13, 2020)

tonyr769 said:


> Hi Dave
> 
> Not sure if your message was for me or the author. Anyway I personally do enjoy tool making having trained as a press tool tool maker. Thanks for your offer but G H Thomas' book is on my Christmas wish list.
> 
> ...



Get BOTH books as I did. His Workshop Techniques is also a fine read


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## Steamchick (Sep 13, 2020)

Nice to see boring the way I was taught in the 1960s... "Transcribe a circle then pass it through the workpiece to get a "perfect" cylinder" as my Father taught me... I made a few boring bars in my teens for various jobs... still have some and use for cylinders. Also use in the Miller for vertically boring cylinder blocks and sets of aligned plumber blocks. (Or are they Plummer blocks? - After a chap of that name?). This method simulated dedicated Boring bars for engine blocks, etc.
K


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## Gordon (Sep 13, 2020)

Apparently I am missing something on G H Thomas books. I am not familiar with them so I looked on Amazon and the price is $218. They would have to be pretty spectacular at that price. Are the books available somewhere at a reasonable price?


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## L98fiero (Sep 13, 2020)

Gordon said:


> Apparently I am missing something on G H Thomas books. I am not familiar with them so I looked on Amazon and the price is $218. They would have to be pretty spectacular at that price. Are the books available somewhere at a reasonable price?


Tee Publishing  £27    https://www.teepublishing.co.uk/books/in-your-workshop/workshop-techniques/
Tee Publishing £27    https://www.teepublishing.co.uk/books/in-your-workshop/model-engineers-workshop-manual/


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## goldstar31 (Sep 13, 2020)

Gordon said:


> Apparently I am missing something on G H Thomas books. I am not familiar with them so I looked on Amazon and the price is $218. They would have to be pretty spectacular at that price. Are the books available somewhere at a reasonable price?



I think the Amazon price is Amazing!
Get them for the Tee price plus postage -- and really enjoy the way that pedantic old guy clearly arrived at things. All of his stuff links together.

When my  Model Engineers Workshop manual was  barely readable from use, I didn't quibble and bought a new copy


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## Gordon (Sep 13, 2020)

Unfortunately that is over $50 US with shipping. Still a lot for a book.


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## L98fiero (Sep 13, 2020)

Gordon said:


> Unfortunately that is over $50 US with shipping. Still a lot for a book.


I feel your pain, but on a positive note, it's less than $218!   At £40.57 a book with shipping it's over $70 Canadian and I noticed that if you order both books, they don't combine shipping, it's just doubled.


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## goldstar31 (Sep 13, 2020)

L98fiero said:


> I feel your pain, but on a positive note, it's less than $218!   At £40.57 a book with shipping it's over $70 Canadian and I noticed that if you order both books, they don't combine shipping, it's just doubled.


 But this is a Manual and includes things like a rotary table from scratch, tool turrets, grinding, improvements to top slides,  how to screwcut and how to cut to a tenth of a thous-- di dah di whilst Workshop Techniques discusses the intrigue of a one hole division plate. I have one and I have a small dividing head.

But a man convinced against his will \is of the same opinion still


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## BaronJ (Sep 13, 2020)

Gordon said:


> Apparently I am missing something on G H Thomas books. I am not familiar with them so I looked on Amazon and the price is $218. They would have to be pretty spectacular at that price. Are the books available somewhere at a reasonable price?



Try Abe books !  Or Tee publishing.

Edit:  I see "Tee Publishing"  has already been mentioned !


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## IanN (Sep 14, 2020)

Part of the problem with books published before 1973 is that the USA refused to abide by the internationally accepted copyright rules until that year.

Before 1973 you had to pay to copyright material in the USA but copyright was acknowledged as a free “right” in the rest of the world (printed on the fly leaf of many UK books published before 1973 are the words “Not for sale in the USA or Canada”)

The large scale, official export of older, reprinted texts is often avoided due to the resulting copyright confusion - see:









						Public domain in the United States - Wikipedia
					






					wikipedia.org
				




Ian


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## Srs41 (Sep 14, 2020)

Check out this item Hemingway Kits Between Centres Boring Bar


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## ignator (Sep 14, 2020)

ignator said:


> There's a youtube channel I watch, a repair machinist, that shows the making of a large line boring bar that may be of interest to his technique and usage:
> 3 part series



Keith Fenner also shows a line bore setup for a large engine block main bearings. This set of videos may be helpful to anyone with too small a machine:


https://www.youtube.com/watch?v=G3F07Z8uRkg


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