The great carbide debate

[Frank&Earnest]

As a consequence of the mushrooming of threads about turning tools made with tungsten carbide cutters, I have done a bit of reading. I do not claim experience or expertise, but I state categorically that I can read. :D

I came to the conclusion that talking about these cutters as suited for woodworking or suited for metalworking is not helpful. The real measurements are in terms of resistance to wear and resistance to impact. There are hundreds of different compositions with minute amounts of different metals, but once these complications are discarded, essentially the simplified equation that interests us is:

the smaller the % of cobalt in the mix the higher the resistance to abrasion (wear);
the larger the % of cobalt in the mix the higher the resistance to impact (strength).

Given that even our toughest Aussie hardwoods are a tad softer than HSS steel, it seems to me that for woodturning wear is more important than strength. The highest resistance to abrasion is provided by cutters with a cobalt content of 3 to 6 %. For example, those I bought on the strength of the "world standard for woodworking" marketing hype are 5%. And over $8 a pop.

The el cheapo inserts that can be bought on Ebay have a cobalt content of 10%, which means passable strength for metalworking and passable wear for woodworking. At $1 a pop, who cares? Room for experimenting with shapes, presentation angles and bisels, which, if the above is correct, are far more important variables.
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.

[TTIT]

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

[hughie]

That said, if you're talking about using the carbide steel to make conventional gouges I'll put my order in right now!:;:U
[/QUOTE]

now theres food for thought. :2tsup:

[Frank&Earnest]

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?

[rsser]

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?

[INVENTOR]

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?
:U

[Frank&Earnest]

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?

[hughie]

:U 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.

[Frank&Earnest]

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! :2tsup:

[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! :2tsup:
[/QUOTE]

No worries, look forward to your ideas

[Frank&Earnest]

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 $$?

[hughie]

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.

[Frank&Earnest]

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?

[hughie]

. 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/detail.asp?Product_ID=0761+1/4+X+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?[/QUOTE]

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

[Frank&Earnest]

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.

[hughie]

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. Well I suppose best way to fit such a bolt is have the head on the opposite side. The point I was making is that we dont want any slop in the hole to the bolt. While everything fits together tight and little or no gaps, there will be no movement and no movement will equate the life span of the tool.Once it starts to move the shaft also will suffer and if the shaft becomes worn then the whole tool is useless and along with it goes buyer confidence.

As to screws there other types available of similar strength ie screws currently in use on engineering machine tooling




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?The actual sizings need to be looked at of both the shaft and TC to arrive at the optimum. That may mean going to a 14mm shaft or 6mm thick tang or even greater.Vertically the base of the cutter is forced up agianst the shaft, here we rely on the strength of the bolt. The bolt is the cheapest item to strengthen, we can obtain good tensile strength in the shaft from standard grades available ie 4140


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.[/quote]

Not sure about the collet.But it could be done with a round tang as you suggest,much the same way gouge tips are done already. It would add to the cost in small runs overall.But if your making 1000's it most likely not be an issue. Also it would be prudent to consider a radius at the round tang as it meets the major diameter and a corresponding radius on the shaft. This would add strength to the tang.

The other alternative is to keep looking other means of securing the TC cutter.

[Frank&Earnest]

The other alternative is to keep looking other means of securing the TC cutter.

...which means plan A and B are no good, keep looking.:D

OK. will do. This has became a dialogue though, nobody else prepared to comment?
BobL, where are you?:D

[robutacion]

Hi gents,

As much as it is against my nature, I thing I will seat back and watch the tool developing. Not that I haven't any ideas, by the contrary, I just don't want to look "imposing" and I think that I will let someone else to have a go.
The problem for me is, be able to discuss and "give some pointers", without becoming too involved, as I always do.

At the moment we have someone with an idea (principal), and also someone with the tools and expertise on metal fabrications to work the technical and physical aspects of this "project". Obviously, it will be of interest that others are able to present other alternatives and or methods, without being to "demanding" or "spoilers". Nevertheless is a lot of room for movement, with this issue, as it will be lots of testing/experimenting in the process.

As I said previously, I would like to be a spectator on this one for a little longer, trying to "unwind" from my other recent tool marathon!:D

Go for it...!

Cheers:2tsup:
RBTCO

[hughie]

.which means plan A and B are no good, keep looking.:D

not necessarily we just keep them on the table and see how it develops


OK. will do. This has became a dialogue though, nobody else prepared to comment?
BobL, where are you?


Oh well it was bound to happen I guess. :U Where I am I? In a land far far away...:U
Sydney

[NeilS]

This is an extremely interesting thread you have underway here, Frank and Hughie. I'm quite excited about the new 'super' gouge that is under gestation here.

As previously admitted, I'm not much of a metal worker so hesitate to contribute. Just one thought, which perhaps highlighting my metallurgic ignorance. Is a screw-on tip out of the question? I imagine the the TC material is compressed in to a die/pattern before sintering. Whether a threaded die could be readily unscrewed from the fragile composite before sintering may answer my question. A threaded tip may also add extra to the material and processing costs.

Neil

[Frank&Earnest]

Thanks for your contribution, Neil. Two streams have converged here: one is how one person could develop and market a new tip specifically made for woodturning, the other is many people experimenting with existing carbide cutters and relating their experiences on this forum.

The two can proceed indipendently, although the sharing of ideas from the forum can help the person with the developing ambitions (Hughie in our case :).)

I have purchased through Ebay a packet of triangular inserts to play with, now I need to purchase a green wheel to sharpen them. Still thinking about making this the theme of the next Adelaide shed meet but haven't done anything to set the ball rolling yet.

[Sawdust Maker]

Hughie
I know you've commented on the steel. ie the stainless is probably not needed (but might look nice :U)
If I was to go out and buy a length for hold the cutter and jam on a handle, what would you suggest? everyday boring 1/2 inch square?
could I cut a length of 1/2 x 1/2 from the neighbours wrought iron gate :o and get away with using that?

[hughie]

I know you've commented on the steel. ie the stainless is probably not needed (but might look nice :U)
If I was to go out and buy a length for hold the cutter and jam on a handle, what would you suggest? everyday boring 1/2 inch square?
could I cut a length of 1/2 x 1/2 from the neighbours wrought iron gate :o and get away with using that?

:U Dont get caught by the neighbour. What he will have on his gate is mild steel and given a reasonable amount of over hang it will bend as it is quite soft. If your going to use MS take the size up some, say maybe 5/8 or 3/4 sq. I would personally look at 3/4 but my style of turning tends to be "a bull at a gate" stuff:U

[woodwork wally]

Gidday all If I may say one or two bits The CiL unit uses 1/2" sqare stainless and works well enough to bust a handle {see cliff Rogers test] and came up trumps otherwise . And also my copy of the same unit is 5/8" using the tips that Cliff brought in and with a nice bevel ground on the support under front of tip and with bevel rubbing produces beautiful shavings and with use as a scraper it peels wood off in a hurry. I am going to proceed along the CiL lines further and am convinced that if length of shaft is maintained at about 8"> 9" then ordinary steel is quite capable of handling anything tha an ordinary guy can hold. as to sharpening the tct be it tungsten or titanium carbide there is an inexpensive[under $100] sharpening unit for circular saw blades that comes on EBAY often and it is equipped with a "stone" to sharpen TCT saw blades as well as ordinary stone and I am making a jig to sharpen my TCT tips . Cliff R if you are reading this mate those tips are great and if you have a couple more to spare I would be in them Cheers to all WW.Wally .

[robutacion]

Yeah, I reckon those 15mm TCT's Cliff ordered are great. Indeed the only ones with a radius, on my series of inserts on tolls , 12, 14,15 & 17mm. I don't believe that Cliff will appart with any of his 4 TCT's but, Craig has gave us 30% discount on his stuff so his inserts are exactly the same as those Cliff got from the USA, I don't see any reason why they couldn't be sent (6 or so) in a normal envelope from the US, as we do in in Australia for .55 cents.

Cheers:2tsup:
RBTCO

[Cliff Rogers]

....my copy of the same unit is 5/8" using the tips that Cliff brought in and with a nice bevel ground on the support under front of tip and with bevel rubbing produces beautiful shavings ....
Interesting, I had never though of making a holder that could have the bevel rubbing, do you have any pics you can post? :think:


.... Cliff R if you are reading this mate those tips are great and if you have a couple more to spare I would be in them ....
I ended up with 5 for myself & I'm hanging on to them.


...his inserts are exactly the same as those Cliff got from the USA, ....
Almost but not quiet, the ones I got from PGS have a 6" radius where as the ones from Easywood are straight, 4" & 2" radius.
Apart from that they fit onto the Ci1 & seem to work just as good but Craig says that they are made of different stuff, I don't know what his are made from so I can't comment any further than to say they look the same & work the same.

[NeilS]

Interesting, I had never though of making a holder that could have the bevel rubbing

Hi Cliff - the holder that Frank kindly made for me, to fit the 15mm inserts you kindly sent to me, has both the bevel on the insert and holder aligned to form an overall bevel. This allowed for the bevel to rub when the tool is raised, resulting in the typical long shavings off the green wood I was using it on. Seemed to work OK to me and resulted in less dust and splinters when used that way. Sorry, no photos.

I'd be hanging onto the few inserts you ended up with after all your efforts to import distribute most of that batch of inserts to everyone else... :)

Neil

[robutacion]

Hi peoples,

Yeah, you're right about the radius, but appart from that, I would believe they are the same or close enough. Anyone can order from PGS, their minimum quantity is 10 and the freight cost is higher just because they come in a small plastic box, that then needed to be rapped in some other sort of legal postage package, on the other hand, and if the inserts you're looking for are either 15mm or 12mm (square or with radius), I would think that Craig will sent any numbers of inserts stick-taped to a piece of light board, and put in a normal envelope, this is perfectly legal and costs only a fraction of the price.
We all got to the conclusion that getting inserts is not the problem, the problem is in the minimum quantities necessary for each of the type an/or size wanted. If there is anyone else that is offering to sell any number and type of TCT inserts, either in Australia or elsewhere, I'm not aware of!, the only one I know, is Craig.

I will ask Craig, and see what he says...!

Cheers:2tsup:
RBTCO

[TTIT]

.............. has both the bevel on the insert and holder aligned to form an overall bevel. This allowed for the bevel to rub when the tool is raised, resulting in the typical long shavings off the green wood I was using it on....................... so now we have a carbide-tipped bedan :shrug:

[robutacion]

:o ohhhh, that's righ...! an TCT tipped Bedan, that should work well, huh?

Next... please....!:doh::D

Cheers:2tsup:
RBTCO

[Sawdust Maker]

:U Dont get caught by the neighbour. What he will have on his gate is mild steel and given a reasonable amount of over hang it will bend as it is quite soft. If your going to use MS take the size up some, say maybe 5/8 or 3/4 sq. I would personally look at 3/4 but my style of turning tends to be "a bull at a gate" stuff:U

So what steel would you suggest for a half inch? I'll probably head up to the ironmongers in the next day or so

[woodwork wally]

Hi Cliff and all others reading this dont blame youCliff for hanging on to them No photo needed I continued from the carbid tip at the same angle for 1 mm. then rounded the rest of in a neat chord to the flat base and as Neil says it just peels shavings if held low and mine was on dry mountain ash as well as on some green with the bevel rubbing . I enjoyed the way it worked . Still needed to finish with a skew but will reduce sharpening that by 70 % so there is a saving in itself I would suggest that anyone who can make up one of these and if you cant then take advantage of the batch on offer as it will save you skew chissels BIG TIME . I've been playing with the metal turning tips and they are barely worth the hassel unless you can sharpen them to the bevels on the CiL or the similar ones that Cliff and others are using Cheers for now WW.Wally