Thread: The great carbide debate

Originally Posted by Frank&Earnest

................The bottom line is that, unless we hit some unforeseen technical limitation (the more foreseeable at this time being the quality of the finish) progress will soon relegate traditional chisels and gouges to the role of quaint darkside tools.

Makes sense? Over to you.

Can't agree I'm afraid F&E. I had a bit more of a play with the Ci1 tonight but this time I took a cut with the conventional gouges for each 'cut' with the Rougher to get a better comparison happening for me. For me, there is just no comparison between a slicing cut with a gouge and the stressful hacking of the Rougher. The Rougher places much higher stresses on me (tennis elbow), the toolrest, drive gear and most importantly the workpiece. A slicing cut with the gouge puts hardly any stress on any of the gear and only a little on my elbow and still removes a lot of waste quickly. I was using both very dry, hard timber (Dead Finish) and soft, very green timber (Orange boxwood cut just 24 hours ago) and found the same benefits/problems either way. I really only see myself using the Rougher to knock the bumps off and that's it. Give me the hiss of a sweet slicing action anyday
That said, if you're talking about using the carbide steel to make conventional gouges I'll put my order in right now!

That said, if you're talking about using the carbide steel to make conventional gouges I'll put my order in right now!

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now theres food for thought.

Actually, Vern, we do not disagree at all. I totally agree with what you said, I had the same experience with my home made rougher, as described in the other threads.

None of this is due to the carbide composition, however, which was the subject of my post. It is due to the other variables we need to experiment with. For example, the cup inserts used by certain hollower tools must certainly produce a totally different cut from a square scraper. In other words, calling it a conventional gouge made of carbide or a carbide insert shaped as a conventional gouge makes no difference, does it?

For those who've tried the Rougher and similar bits, a thought: for spindle roughing would the finish improve if the cutter were presented at a shear angle?

...

Good stuff F&E.

In reading about tool steels, it appears there are three qualities of interest: hardness (eg. Rockwell rating), toughness (or brittleness, so resistance to chipping), and abrasion resistance.

For hand tools you can increase hardness but only at the expense of toughness. This is with CS of course. Not sure how the trade-off might play out with HSS.

For the techos, how does bumping up the Vanadium content affect those three qualities?

In a funny way I like reading the debates on TC tools. It must be over ten years ago I ( probably like a lot of others) fitted TC inserts to tools to see how they would go. I even tried the TC cutters from Arbortec on some.
I was convinced that it would be the way to go. ( when us turners caught up) how long have we had TC tip saw blades?

I even wondered if someone would try ceramic?

I think its positive to try different types but most I think are just metal working cutters bolted onto a piece of bar. I 've made a heap over the years.

BUT when is someone going to make a whole tool tip ( shaped like a gouge) out of tungsten? like the HSS units that KELTON AND WOODCUT make.

OR some other better shape???
Then we might get something that actually works like we all want.

What do you think?

I think it would be like going to the restaurant instead of learning to cook, but as far as the recipe of the dish is concerned, the only difficulty with us shaping a piece of TC exactly like a traditional tool blade, keeping in mind that what is behind the bisel does not matter, is to find among the thousands of already made inserts the one that can be ground to that particular shape.

What we really want is to create better tools, not to copy old ones.

Either way, to get a "gouge like" TC tip is quite simple, we would just need to get enough people interested to buy one and order the minimum production run from a Chinese manufacturer. If it works for the Leady lathe, why should it not work for something so much simpler?

Ok heres my 2bobs worth.

TCT tip that are custom made generally are bought by the kilo and its no problem getting the tips made.
Have tip made like some of HSS gouges such as

http://www.henrytaylortools.co.uk/hss3.html

This would very expensive due the amount of TC needed. Its no accident that in engineering tips area kept to a minimum size.

That leaves a tip that is attached much like an engineering tip ie some sort of locking device that allowed a quick change over or silver soldered in place.

Obviously the locking device is the way to go as it allows for smaller amounts of tungsten and the convenience of changing.

But it would be a bit tricky coming up with locking device that could hold a small U shape TCT to a gouge blank. I dont think its impossible but it aint gonna be easy. I have few ideas but not the resources to look into it. At the moment I am looking at recycling old tips.

Yes Hughie, we seem to be on the same wave length. I'll make a few designs and you may review and improve them with your practical experience, we might go somewhere!

we seem to be on the same wave length. I'll make a few designs and you may review and improve them with your practical experience, we might go somewhere!

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No worries, look forward to your ideas

Ok, first thought, pretty easy if it works.

One 12mm diametre tip like this would be about 2 cubic cm. I do not know the specific gravity of TC but I guess that would be less than 40g a tip. What does that mean in $$?

F&E,

might have rotate your tang into the vertical otherwise the brittleness of TC would allow it to fracture. Then change your holding screw to a shoulder bolt to secure the insert.

Thanks Hughie. I understand that a vertical tang would be stronger but do not understand the advantage of a shoulder bolt.

As regards weight mine was a reasonable guess , a 5% Co mix would be about 18.73 grams a cubic centimetre. There should be around 25 tips in a kilo then. Any guesses regards the price?

. I understand that a vertical tang would be stronger but do not understand the advantage of a shoulder bolt.

A shoulder bolt provides a accurate diameter out of HT steel. If we used say a Allen cap screw which is high tensile steel. The plain diameter is much smaller than the threaded portion.This because the thread is rolled on not cut on. Any slop here would add to problem.The rolling of threads in pretty well universal on bolts, so the plain areas are always smaller.

https://www.allensfasteners.com/deta...+SHOULDER+BOLT

As regards weight mine was a reasonable guess , a 5% Co mix would be about 18.73 grams a cubic centimetre. There should be around 25 tips in a kilo then. Any guesses regards the price?

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Dunno, my prices are several years out of date. It seems they are all in China these days

http://www.cn-hongfeng.com/index2.htm

I get your point about strength, I wonder whether the risk of the HT Allen screw failing is large enough to warrant the loss of functionality caused by the protrusion of the bolt either side of the bar, given that on a 12mm bar there would be not enough room for recessing the head and the nut. The screw I have used for my Ci1 clone is the same as the one used to hold the GPW chuck jaws (6mm d 12mm l, 12.9 steel), seems quite strong enough.

Now that I think about it, if TC brittleness is a concern for the horizontal tang, say 4mm thick and 12mm wide at the diametre, where the width of the hole is largely irrelevant and a bigger concern would be the bottom of the bar flexing and the screw thread in the top of the bar stripping (the advantage of the bolt then being greater, a bit less intrusive if vertical), would it not be worse if the tang is vertical, given that the main force would be applied on the CT above and under the say 5mm hole, which would be only 3.5mm thick and 4mm wide?

Another thought: if a tang is not strong enough and the added length of a bolt is not too cumbersome, would it not be a better idea to keep the end of the tip cylindrical and insert it in a collet, holding it with a small grub screw? It would add to the weight and cost of the tip but improve the ease of changing tips.