How to shape carbide tools

[Mr.B]

At present I hand grind 3mm dia Tungstencarbide bars into 1mm wide cutting tools for my lathe.
I am using  a white stone and a green stone on a bench grinder.
The results are a bit hit and miss.
Would like some advice on what to use eg do I need a diamond cup wheel ? if so what grit ? can I mount it on a bench grinder? or do I need special machine?
Thanks for any tips in advance

Bernard

[PTsideshow]

I was at our turning club's local meeting yesterday, during the demo the guy's carbide insert turning tool got dull. Now as I understand it this will only work with the type of inserts that have No relief or undercut on the top surface. Flat and level, somebody else used the 3 diamond sharpening/honing blocks here in the US they are red fine 360, blue coarse 180 and yellow medium 260, colored plastic filling the hole in the plates.
Depending on how dull the insert is you can start out with which ever grit you think will do the job. He makes one pass and the turns the insert either 4 sides or 3 sides for a triangle one.

I think that you should be able to dress your home made bit with the same kind of hone.  He said he does it till the edge corner is sharp, now a sharp edge is better for wood and plastic turning but you could dress the edge after a couple of try's. That would work with your bits. If not the you will need the special wheels to sharpen them.

They put it back on the tool handle and went back to cutting, worked like a new insert according to the turner!

[trevoratxtal]

Hello Pt
Here in the UK I have used
http://www.arceurotrade.co.uk/Catalogue/Diamond-Tools/Diamond-Grinding-Wheels
 
I get a super edge on all carbide tools
Grit size as shown.
A search such as "diamond wheel usa" should find you a suppler.
Trev

[Mr.B]

Thanks Trev I had been looking at those wheels on arceurotrade. Could you tell me? do you just bolt that wheel onto a bench grinder spindle or is there something special.
My first fear is how do you get it to run true, and do they last very long if removing 2mm of material at a time?
The green stone I use at present is fine for an edge but goes out of shape quickly if you ask it to do more.
Do you have to use water when sharpening?

Thanks again

Bernard (a Scotsman in England)

[trevoratxtal]

Hello Bernard
The center hole is accurate as in concentric,you may have to turn up a bush to fit whatever spindle you use whether a bench grinder or a tool cutter grinder.
I have several different shape wheels as I also sharpen my Mills  Taps
Chisels Knives punches and any thing else.
 I never found they run out of true.I think one vibrates a little but did not effect the sharpening.
I have used mine for over 5 years with no sign of wear, nearly all my lathe tools are carbide.
I also have a number of carbide drills and they are sharpened with the diamond wheel.
At times I have chipped a drill or lathe tool and ground back to shape so 2mm is not a lot and does not seem to wear the wheel.
I grind at high speed and dry.
Don't let the tool get to hot and don't quench as it may cause hair cracks.
As for Green stone! never again for me I could never get the edge I required.
Regards
Trev

[Mr.B]

Thanks for the advice trev, will put in an order for a couple of wheels and give it a go. At least I can do this now with a little more confidence cause I hate wasting money (it must be in the blood).
Thanks for your help.

Bernard

[trevoratxtal]

Bernard
Please lets us know how you get on, your experience of fitting and using the wheels  is just as relevant as any one else.
Hopefully we are all followers of Mad Modder to share our thoughts as well as gain ideas.
 
I wish you the best
Trev.

[trevoratxtal]

Hello PT
""the 3 diamond sharpening/honing blocks here in the US they are red fine 360, blue coarse 180 and yellow medium 260, colored plastic filling the hole in the plates.""
 
I find these are of use on large items such as chisels and plane irons, but to trim up a small lathe tool or drill, the holes snagged the work, I purchased some rather expensive Diamond files but they were to coarse for sharpening, I am still on the lookout for solid Diamond honing  blocks. I.E no holes.
Trev

[PekkaNF]

Very interested to hear how foray for the diamond wheels comes to fruitition. Truing and opening of them seems to be a special process.

I use "DIANOVA" for manual honing
http://www.dianova-ab.se/productinfo.php?lang=eng

These are whole lot better than most look alikes. They are pricey, but very good.

Cheaper ones does not have very true surface where abrassive is bonded, there are much coarser particles in mix and there is less particles and they are not spread evenly. Often they look decent on retail pagage, but you'll notice the difference when you compare results with loupe.

PekkaNF

[Ned Ludd]

Hi Trev,
As you are in the right part of the world try APTC.
Ned

[PTsideshow]

The inserts that I use with my Sherline lather are the TMNG ones here in the states they can be had for $2.00 or so on sale. that is the reason the guy that invented the Plastool holders did so with those inserts because he said hey are the cheapest and most commonly available ones.

The ones used for the wood turning tools that are made by a number of pen turners, use inserts for the moulder and planer heads. they have a sharper edge at the corner. Something that isn't required for most metal work.

And since they last a lot longer than when in use for metals. Dressing the edge will work to extend the life of the insert for wood working.

I haven't tried it yet as my pen pro tool is still little used. Due to life getting in the way 
pen pro tools

If it even works sort of for the wood inserts it will ok, as I don't for see me becoming a production turner! Plus I don't need another grinder set up.  I bought a couple dozen TMNG's when wholesale tool had a clearance sale a year or so ago.
    

[Mr.B]

Ok Iv'e bitten the bullet and ordered a diamond wheel from arceuro.
Next problem The bore size of the wheel is 32mm and my grinder has a 12.7mm shaft.
Can't find an adapter on the net anywhere so I think I will have to turn one.
Should I use Alu or Brass or Nylon which would be best are there any rules for this?

Bernard

[trevoratxtal]

Ned just looked up Axminster as suggested at 
http://www.axminster.co.uk/diamond-stones-dept208002/
Two items look good so I will arrange a trip soon and look.
What I love about Axminster is you get to handle any thing you are interested in, I try to make a least one trip a year on my Birthday,
 
 lots of money in my pocket.
Trev

[Mr.B]

The wheel arrived today.
Got about mounting it on my little bench grinder.
Made up 2 stepped spacer rings to adapt from a 12.7 shaft to a 32mm hole. It sounds so easy when you say it quick, it took me over an hour of turning on my little sherline lathe.
Then after two cups of coffee set about getting it to run true, can honestly say is was a bitch. But after a few attempts and the wife saying what's wrong with your face ( nothing I'm thinking dear) I finaly got it.

Tried out a test run and Oh my god what a difference, it removes carbide like butter and what an edge.

A very happy Scotsman and all for 35 quid. Thank's to Trev for your advice it helped me a lot.

Below are a couple of pictures of the almost finished Grinder.

 

[trevoratxtal]

I am pleased you are happy Bernard, as you say what an edge!
I do like your photos, it says so much.
Regards
Trev
 
Ps I have a fetish about sharp tools, I just love that polished look that the Diamond wheels gives.

[Mr.B]

One last thing.

How do you clean the wheel.

I think I read that you can use a pumis stone or am I getting confused with something else.

[trevoratxtal]

Sorry to be slow to answer you about cleaning the wheel.
The truth is I have never had need to as yet so I do not know.
 
Trev

[Doc]

To clean a diamond/cbn wheel you use a cleaning stick.
cleaning stick