Bars for Boring Head

[adamcowmanParticipant @adamcowman]

How ya lads

Recently got myself a good quality boring head for my mill at a yard sale recently and want to get it setup.

it came with a load of toolbars that take hss toolbits but I want to get a set of bars with carbide inserts. Trouble is I can’t figure which bars to buy size wise. The seller told me the boring head took 3/4” tools, which makes sense cos it’s from the imperial era. But measuring the holes they all come out at around 18.6 – 18.7mm. So do I get standard 18mm bars or try find 3/4” ones. My tooling supplier can’t get me any 3/4” as he only stocks 18mm and 20mm.

I could modify the bars but that’s a hassle I’d rather avoid. Leaning towards buying 18mm bars that the head can clamp on the flat so should be no play/riggidity issues.
Im relatively new to machining so never used a boring head before and don’t want to spend money on the wrong tools.

Thanks.

[JasonBModerator @jasonb]

Well you could grind up a bit of Carbide and put that in your holders they won’t know the difference between HSS or Carbide. Old milling cutter shanks work well enough or just buy blanks.

Do you really need the bars to be that big? For a lot of work you could simply sleeve the bore down to 12mm or 1/2″ and then buy the insert holders made specifically for boring heads. I mostly use these

Have you actually tried something exactly 3/4″ in the holes, I expect they will fit.

[JohnFParticipant @johnf59703]

The sizes you quoted are odd ball !  3/4″ is 19.05mm so aim for 19mm or something you can turn down to 3/4″

It may help to know what make of boring head is it ? Plus a photo of what accessories you have with it.

John

[adamcowmanParticipant @adamcowman]

Ill try attach some pics here now. No brand on the head itself and only a part number on the box. The head itself is quite big compared to a modern one with 18mm holes.

Never thought to make a sleeve i suppose it would be the handiest thing to do really. Only picked it up yesterday so havent got to try much in it yet. The bars that came with it fit of cource but a 19mm drill bit i have doesnt the holes. 

[David George 1Participant @davidgeorge1]

I have Many diferent boring bars for my boring head. I have silver steel turned down to match the boring head which gives a more solid bar for large bored holes. These have holes drilled for HSS or carbide round bar with grub screws. Others have carbide tips brazed on to act like bought bars and to lengths which suit job in hand.

David

 

 

 

[FulmenParticipant @fulmen]

I just use small indexable boring bars from the lathe in a sleeve.

[Nigel Graham 2Participant @nigelgraham2]

Adam –

Aha! That looks very much the same as mine, apparently “made in France” for Colchester [Tools ??]!

I will examine mine and see what that might reveal…… I’ll try for diameters and any Part or Serial numbers, on it and its rather nice wooden box.

I’m not sure what the arbor taper is on yours. Mine is R8, to fit my Myford mill (also the standard for Bridgeport among many others).

[adamcowmanParticipant @adamcowman]

Please do  Nigel that would be a great help

Taper on mine is a iso40 taper but ive an R8 one to replace it for my bridgeport.

[David George 1Participant @davidgeorge1]

Hi Adam if you bought some 20mm diameter shank boring bars they are machinable on the location diameter. I would hold them in my four jaw chuck and using a dial indicator set them true and maybe some packing on the jaws, to ensure the cutting tip is not damaged, and with a centre in the end just turn them to match the diameter of the holder using possibly a carbide turning tool.

David

[JasonBModerator @jasonb]

Or just buy a 3/4″ one intended for the US market but as that is only likely to go down to about a 1″ hole you will still need something for the smaller holes. The smaller bars also don’t unbalance the head so much which means you can run the head faster though still they generally need to run below optimum cutting speed.

[Clive FosterParticipant @clivefoster55965]

Certainly looks like a French made Gamet boring head.

Enco in the USA sold a lot of these in three or four sizes so it may be worth a trawl around the Americentric sites for data.

General opinion seems to be that these are a solid, workday, piece of kit.

Clive

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