Thread: Hardface welding stick and wood cutting ?

I would first discuss it with the bank manager

http://astroalloys.com.au/shop/astro-hss-1/

They are not going to be cheap

Oh No

Thanks RC , I will look into it .

I bet they only come in large quantities as well .

The Tap cuts a 62mm thread through wood and has four teeth which progressively take a larger bite as it turns, number one has the big chip.

When the Mig welder is used , a weld quickly quenched in water while red hot goes hard . has this ever been used in a hardfacing sort of way ?

Rob

picture ?

I relay cant see what I am looking at in the pictures.

But if it is a commercially made cutting tool, the edge will either be tool steel or carbide.

Nothing you will lay up with a welder will even come close in hardness.

If the edge is an attached piece it will be brazed or silver soldered.

Back when saw blades where expensive, I had several tooth tips replaced by saw doctors.

The take a piece of carbide about the right size, braze it in place and then grind it to match the other teeth...good as new.

If the tool you are looking at is one piece and of any hardened and tempered form, welding on it is likely to ruin the temper in the tool and it would then need to be heat treated .

If it is high grade tool steel...ya won't be managing this most workshops.

I'd be getting a saw doctor to look at it.

cheers

What is that thing?
The chip seems to be minor, what if you just leave it as it is?

Its a tap and die set for wood , 62mm diameter . The kind used in wooden work bench threads. I used this tool doing my bench threads out of Redgum 20 years ago . and I chipped the tool back then. There are no brazed on teeth . Its been turned out of a solid piece of steel then hardened, I think ?

What I have shown in the pictures is tooth number one which has lost its leading cutting edge, as the tool rotates three more deeper cuts take place . The second picture is the fourth full cut , if I turn the tool around, two different height teeth are in between the first and fourth.

I could leave it because it does still work as it is , but not as nice as it should work.
I could possibly grind back the chipped area to form a cutting edge.
It would be nice to be able to restore the missing metal though , and grind the other teeth the way they should have been sharpened in the first place .

The problem started because a previous owner to the guy I borrowed them off, sharpened the wrong side of the tooth which reduced its cutting size. what followed the cut was a larger tool than the cut made for it and it jammed badly . I was told to stick a piece of hard steel in the hole and use a pipe for leverage to get it to turn . That's how I broke it. very embarrassing I had to return the tool broken . That was 20 years back . this week the owner asked if I wanted to buy the two sets of cutters , a 32 and the 62mm . I paid his price and took them . They are a spectacular thing to watch working , specially the die, that has two cutters .

If it still works I would leave it.

The fact that it chipped like that suggests that it is under significant load during use so any home based repair is going to be suspect while its under load.

If you are determined to get it somewhere back to its former glory then I reckon Soundman's idea of a saw doctor is worthy.

Yeah Bob , I wont rush into it any way , I will just sit and consider for a bit .
When I did break it I went all over Melbourne asking different metal workers what they thought . I ended up at an aircraft engineers work shop and he nodded and said no . I think they were not willing to take the risk of it not working and they had better things to do than waste their time on me as well.

I was thinking of burying most of the tool in wet sand and grinding back the excess weld with diamond coated rotary tools ?

If it is a single piece tool, you do not want to be heating it in any way anywhere.

It will have been machined and then hardened and tempered.

Very likly it will be simple high carbon tool steel, not alloy tool steel and will loose its temper very easily.

It would be worth doing some simple tests to establish what sort of steel it is.

Grinder spark tests come to mind.

Knowing what we no know....I think there are two practical choices.

1/ leave it alone
2/ CAREFULLY sharpen a new leading cutting edge.

Anything else ya probably better buying a new one of having a new one made from scratch.

cheers

I wonder if a new cutting edge out of tungsten or high speed steel could be brazed to it. I Would get it done by a tooling sharpening shop and would not attempt to grind anything myself.

Very repairable.
Option A, an air hardening tig filler wire. Usually only available in large packs.
Option B, Cobalarc Toolcraft electrodes - available in a 20 rod handy pack. http://www.cigweld.com.au/product/ha...arc-toolcraft/
Option C, Tig weld with an old drill bit. I have actually done this to repair a die where some numpty left a 12" shifter before the top punch came down. Once ground off it was as hard as a goats forehead and is working to this day as far as I am aware. The Toolcraft electrodes are a good bit of gear too, I've repaired many a set of bolt cutter jaws with them. The secret is to only put the minimum of heat into the job.
Tig is the weapon of choice for work such as this because it is an intense arc, only causes localised heat and is so controllable. The hardest part will be accurately grinding the deposit to shape.

I use hard facing rods on the studs in Almond crackers. The ones that I have are quite thick (app 4mm) like a rolled tube coated in flux. Getting a solid weld, with good penetration with such a rod into that location without spreading it all over the place isn't going to be easy. Excess can be ground away but it isnt easy and it would be very hard to shape it to a tooth. The material isnt that hard but it is certainly a lot harder than mild steel or quenched MIG wire.

If you want a rod PM me and I will post one.

As others have suggested I would carefully grind the remainder to shape.

Regards

Ian

Originally Posted by Karl Robbers

...Tig weld with an old drill bit. I have actually done this to repair a die where some numpty left a 12" shifter before the top punch came down. Once ground off it was as hard as a goats forehead and is working to this day as far as I am aware.

Are you saying that you welded a HSS drill bit to a die and then ground it off or filled a cavity in a die using a HSS drill bit as filler? Either way sounds interesting...

Michael

Originally Posted by Michael G

Are you saying that you welded a HSS drill bit to a die and then ground it off or filled a cavity in a die using a HSS drill bit as filler? Either way sounds interesting...

Michael

We used the HSS drill bits as filler material. Desperation is the mother of invention - urgent phone call right on home time, machine down, life and death production run, quick look around the workshop - hmm, 1.6 super steel filler wire, 1.6 316 stainless, neither of those were going to cut it. Broken 6mm drill bit, we'll give that a go and it worked. I was as surprised as anyone.
We gently warmed then whole die to probably 50 or 60 degrees in order to lessen thermal shock and then just filled in the various dings and depressions left by the shifter, allowed it to cool and then carefully ground off the excess, sanded, then ran a velcro pad with a red scotchbrite to blend and polish the area. Based on the way it ground and sanded, hardness seemed comparable to the actual die.
Thinking back, we also repaired chipped punches from the punch and shear using HSS drill bits quite effectively too.
If I were doing the same job regularly, then I would source the correct filler from Bohler Uddeholme, ESAB or Eutectic Castolin - $$$$$$, but as a down and dirty fix at short notice the HSS drill bits worked really well.