Thread: Boring bar Materials

all steels deflect by the same amount up to their yield point...

a piece of 4140 and a piece of 1018 of the same dimensions with the same force applied to them will deflect the same amount...

Put more force on them though the 1018 will permanently deform (bend) before the 4140 will...

I have a couple out of 4140 for two reasons... Firstly it or 1018 is the only thing available locally off the shelf and secondly I can harden 4140 with just a torch and that hardens the surface enough that the bar does not get injured...

Being in Mackay something like 1045 might be cheaper to get...

Hello Grahame, I made a couple of boring bars to take carbide inserts from the shaft from a Macpherson Strut. It was 22mm dia. I don't know what vehicle it came from. Maybe a Suspension place could help . Russell

I have made a few to suit what i was doing. I just used what steel i could find in my junk box...Bob

Originally Posted by .RC.

all steels deflect by the same amount up to their yield point...

a piece of 4140 and a piece of 1018 of the same dimensions with the same force applied to them will deflect the same amount...

Put more force on them though the 1018 will permanently deform (bend) before the 4140 will...

I have a couple out of 4140 for two reasons... Firstly it or 1018 is the only thing available locally off the shelf and secondly I can harden 4140 with just a torch and that hardens the surface enough that the bar does not get injured...

Being in Mackay something like 1045 might be cheaper to get...

RC,

Is there any chance that you could describe your heat treatment process in more detail?

Bob.

great photos. a square sided boring bar with a round hole. brilliant.

Originally Posted by aametalmaster

I have made a few to suit what i was doing. I just used what steel i could find in my junk box...Bob

because your not swarfmaker i wont ask if you really made all that swarf

Wow ,
Thanks fellas!
There's already a wealth of information there already.We keep suffering budget cuts and the cost of maintainence doesn't help either,so I have to economize when and wherever I can.

The Machperson strut materials sounds cost effective as I can probably bum them from someone.
Its a good reminder that there are some wonderful recycleable materials in motor vehicles - claims 10 ECO points here!.

At one time I was asked to solver solder tungsten material to boring bars for the fitters in our factory. I take it that was the same as "cemented carbide"
Are the new technolgy inserts capable of being silver soldered into a bar.

I would like to attempt to silver solder some undamaged insert cutting edges into to a compatible bar or am I dreaming.

Usually these will be required for one off applications.

Cheers
Grahame

Originally Posted by azzrock

great photos. a square sided boring bar with a round hole. brilliant.

And my first grade teacher said a square peg won't fit a round hole. She didn't fool me ...Bob

Originally Posted by Grahame Collins

Wow ,

At one time I was asked to solver solder tungsten material to boring bars for the fitters in our factory. I take it that was the same as "cemented carbide"
Are the new technolgy inserts capable of being silver soldered into a bar.

I would like to attempt to silver solder some undamaged insert cutting edges into to a compatible bar or am I dreaming.

Usually these will be required for one off applications.

Cheers
Grahame

Graham,
Modern inserts can be brazed to steel shanks provided the braze surfaces are cleaned to remove the oxides that are formed on the surfaces during the sintering operation or the exotic coatings on coated inserts.
Cleaning can be done by light grinding or pickling. A good test as to whether the surface will braze successfully is to heat the carbide blank with s small strip of silver solder on the surface, if it flows over the surface it will braze..if it forms a globule (raindrop) it will be a poor joint. Wetability is the key.
Col
PS "cemented carbide" refers to the tungsten grains cemented into the Cobalt matrix

Originally Posted by Anorak Bob

RC,

Is there any chance that you could describe your heat treatment process in more detail?

Bob.

Cover part with soap.. Heat to dark red with LPG burner ... dunk in oil... polish and temper..

rough but it seems to work..

Thank you RC. I will give it a go.

Grahame,
I'm yet to make any home made carbide boring bars. The HSS ones I have made are just 25mm SQ black with a 5/16 slot milled along one side so that the top of the slot is at center height or a little above. I'm sure its a little on the slow side but it could be improved.

Originally Posted by Col2310

Modern inserts can be brazed to steel shanks provided the braze surfaces are cleaned to remove the oxides that are formed on the surfaces during the sintering operation or the exotic coatings on coated inserts.

Col,
Another thing I had heard is that the meeting faces both need to be flat of the insert may crack on cooling. Have you heard of this?
Thanks
Stuart

Originally Posted by Stustoys

Grahame,
I

Col,
Another thing I had heard is that the meeting faces both need to be flat of the insert may crack on cooling. Have you heard of this?
Thanks
Stuart

Stuart,
Slender or thin carbide blanks and the harder grades are more difficult to torch braze due to uneven cooling/shrinkage rates between shank and carbide.
Pre heating the shank and cooling the brazed part slowly, preferably is mica or similar material, will limit the risks.
Also, do not enclose the carbide. Just braze the base and one supporting shoulder if required.
Position the torch under the shank letting the heat flow through to the blank and use good flux.
Col

Greetings Chaps. I have found that as long a the exotic coverings on the tip are removed and the surface to have the tip is tinned it is OK. After tinning an old pair of vise grip plyers are use to hold the tip in place while the tip is fused on. I have used Tobin brinze as the braising material it is cheaper than silver solder which is what they used to use. Mild steel is OK and readily available Hex Bar is the go. I have on the odd occasion arc welded a lump of HSS to the end of a lump of MS to get me out of trouble. I did not quench this bit but let it cool down naturally. It is surprising how the HSS stood up. Another lurk is to try and find tips with a hole in them.drill and tap a bit of hex bar. File a sholder on the bar so the tip can not turn and bobs yer uncle. Yours 4-6-4

Originally Posted by .RC.

Cover part with soap..

Why the soap RC?