Thread: What steel for brazed carbide tooling?

Originally Posted by Ben Dono

I stumbled across a few videos of people brazing old indexable tips to square stock. Any idea what the base steel is?
I'm guessing it's a tool steel of some kind but I can't find any info on it.
4140 maybe?

Ha, I've been doing that for years. Any old HARD steel will do for the holder or boring bar. You certainly don't need tool steel for the holder - it's not doing any cutting.

All my boring bars are home made using recycled carbide inserts, and they work as good as anything you can buy.

But you DO need a hard bronze brazing system for this to work. I use a Bullfinch LPG gun, but MAPP or oxy are the other options.

You also need a green grindstone to rejig the carbide profile afterwards.

Save a small fortune making your own tooling.

Piece of cake to do it.

Cheers

Rob

Mild steel is good enough, unless you plan on putting enough force into it to bend it...

Remember most steels nearly bend at the same rate if the same load is applied... It is how much they can bend before permanent deformation sets in (yield point) that sets steels apart...

You will struggle to find square section steel in anything but mild steel anyway in Australia...

If you want a medium carbon steel in square, buy a length of key steel.

Michael

Originally Posted by nearnexus

Ha, I've been doing that for years. Any old HARD steel will do for the holder or boring bar. You certainly don't need tool steel for the holder - it's not doing any cutting.

All my boring bars are home made using recycled carbide inserts, and they work as good as anything you can buy.
But you DO need a hard bronze brazing system for this to work. I use a Bullfinch LPG gun, but MAPP or oxy are the other options.
You also need a green grindstone to rejig the carbide profile afterwards.
Save a small fortune making your own tooling.
Piece of cake to do it.

Cheers

Rob

I agree ! I've used an old knackered 22mm x 6mm square carbide tip brazed diagonally into a slot cut in the end of a 20" length of 1/2" rod, suitably ground to make a long masonary drill when I needed to put a hole through a double brick wall for a plastic conduit. I used that home made drill again recently to drill through a stone wall when puting up a security light.

Tops, thanks for the info guys.
Yeah, I have quite a few of the tips lying around and I will have a play with it. I think I might knock up some shorter boring bars.
I have a big mapp gun but need to pick up some proper rods. I already have plenty of plumbers 3% and 5% and a small amount of 45% for the odd stuff. Any tips on what the right rods might be?

On a side note, I have found a little floor and wall made out of light weight fire bricks really help get your temperatures up fast when your using the small burners.

Is their any point to trying to braze hss tips? Could have some benefits when trying to make up some odd tooling or long drills.

Originally Posted by Ben Dono

I'm going to skip past the H&F indexable tooling. Surely their is a better option for small lathes!

Thats a good move for starters.people don't realise until they chase spares that H&F tooling spares, unlike other commercial tooling spares will only fit the H&F tooling. In other words if you damage or loose a part, H&F or their resellers is the only source of that part. As teacher whose responsibility it was to keep the five lathes we had going, it was very inconvenient not being able to source local spares.
With a change to some commercial tooling I was able to go to the local tooling guy and buy the parts and have the lathe going in 24 hrs not weeks.

If its a smallish lathe some cold rolled section might do the job?

Grahame

Originally Posted by Michael G

If you want a medium carbon steel in square, buy a length of key steel.

Michael

+1

Also, you will need to break up the carbide tip if you want to make a small boring bar etc.

Just wrap the carbide in a rag, and hit it with a hammer on the vise.

You can hard bronze HSS for some jobs (eg. I used HSS when I cut a 5/8" internal LH Acme thread recently) where tip profiling is critical.

Use plain general purpose brazing rods. That way you can add the right amount of flux for the job. I never use pre-fluxed rods.

Cheers

Rob

Originally Posted by Ben Dono

. I already have plenty of plumbers 3% and 5% and a small amount of 45% for the odd stuff. Any tips on what the right rods might be?

3% and 5% is rubbish..one should use a minimum of 15% for cu to cu, and they (and 15%) are no good for steel

45% is okay and use flux

Tops! I'm going to have a play with all that info. I'm not a fan of pre fluxed rods either. I much prefer to put the flux where I want the filler rod to flow. Mind you I think I have forgotten what proper flux should feel like! I bought a large plumbers supply of it 15yrs ago. I just keep adding water to it to thin it up a little as it sets like clag glue. Probably time I bought some fresh flux!

Thanks everyone for the information!

On a side note, I picked up an 80mm six tip indexable face mill when I bought my milling machine from H&F. I specifically asked for one that takes regular commercial cutters. I have not replaced them yet but I bet I will only find them at H&F! It's a great cutter, just a poor machinist!

The flux I use is basic Ezi 303. This is a pink powder type flux that you use dry.

Heat the tip of the rod and dip it in the flux for it to stick, then wipe it on the red hot job.

BOC should have it.

Pretty cheap (from memory).

Also easiest to use the small diameter bronze rods (2.3mm ?).

Rob

Rob I will give that a go!

I was always taught to put flux on where you want the filler rod to flow.
I will grab some of the powder next week. It sounds like your method will be a bit neater as when I paste flux the join, it runs a bit and the filler rod always follows the run.

Originally Posted by Ben Dono

Rob I will give that a go!

I was always taught to put flux on where you want the filler rod to flow.
I will grab some of the powder next week. It sounds like your method will be a bit neater as when I paste flux the join, it runs a bit and the filler rod always follows the run.

Yes, this method allows you to wipe the flux powder on where you want the rod to flow.

The flux goes clear and flows like water. Very easy to be accurate and have good control.

When pre fluxed, just add the bronze rod as required.

Clean up with water and the wire wheel.

Rob

Thanks mate! Pardon the pun but I will give it a red hot go!

Great thread guys.
Reckon I might have a crack at this too.

Phil