Thread: new carbide chisels

I use the Mini PenPro that WoodNworkshop used to sell, I love it.
It works best at 3000-3500rpm.
In my shed it gets used for all pen blank materials, I start sanding at 400 w&d.

i purchased a set of carbide chisels ... they now sit over the back of the bench collecting dust ... i don't like them at all

HSS ... all the way

I had a similar problem with cheap Asian carbide inserts for a Thicknesser. A mate owns it and had tried to save a bit of cash by purchasing cheap carbide inserts from China via Ebay. He was having trouble with them, and asked me to have a look. Just handling the inserts - you could barely feel a cutting edge - you certainly were not at risk of cutting yourself with them. Had a close look at the cutting edge with a magnifying glass, and found that the bevel appeared to have been ground OK, but that the back face of the cutting edge was only roughly ground.

We ended up lapping the back surfaces of the carbide inserts by rubbing them on his diamond sharpening plates. Started with a course diamond plate, and then finished off with a fine diamond plate. We didn't attempt to do anything with the bevels. Simply place the insert on the wet diamond plate with the bevel side up, and used a finger to move the insert in a figure 8 pattern. We knew we were on the right track when Ian finished lapping the first insert and promptly cut his finger on the sharp edge.

Each insert took about three minutes of lapping on each grade of Diamond Plate to get a good sharp edge. Those inserts then worked great in his thicknesser, and as far as I know he hasn't had to repeat the lapping process in the last year or so. It took us a couple of hours to do the set of inserts for his thicknesser, but it looks like it will be a on-off activity for the life of those inserts. At the time, I did some Googling and did find a few Youtube videos that showed jigs that people had made to allow them to lap the bevels on carbide inserts - but I've never tried that - sounds just a bit too fiddly for me.

So, I'd suggest doing the same with your wood lathe tool carbide inserts. Have a close look at the cutting edges with a magnifying glass first, and test the edge against your finger nail. If it's not at least as sharp as you'd normally sharpen a HSS wood lathe tool, then try the diamond plate lapping method. As you've already found out, a blunt Carbide Tool is pretty useless.

There is a caveat - I understand that there are different hardness grades for carbide. The cheap Asian inserts may have been a less hard grade of carbide. You may have less success if you are trying to lap a significantly harder grade of carbide. But - you won't know until you try.

Regards,

RoyG

Thanks Roy, I didn't even think to try and sharpen it! I'll try as soon as I get home

Only problem is people taking full width (of the cutter head) cuts. Don't do it. Either use a curved or even better round tip, but use only a small portion preferably a single point of cut

The tip I have is a round one. Even with a gentle touch it still wants to dig in and tear instead of shave the timber. I think like Roy said, its just very blunt. A bit disappointing considering it was a well know top of the line brand. My first impression of it was very good but I think that's because it was new and I wanted it to be! On finer evaluation it wasn't so.
I'll give it a sharpen and see how it goes.

Originally Posted by asheddie

..Even with a gentle touch it still wants to dig in and tear instead of shave the timber..I'll give it a sharpen and see how it goes.

It needs to be sharp so do that. But also be careful your angle of approach to the work is at 90 degrees and at or below centre, that way if you have a catch, the blade falls away rather than digging in