Good quality hollow chisel mortise bits

[Xanthorrhoeas]

I have a Chinese benchtop hollow chisel mortiser that I purchased some years ago. It has had little use and the one of reasons for that is that I find that the standard Chinese mortise bits are quite ineffective in Australian hardwoods like Bluegum (the other main reason is that I have not been making anything that needed mortice and tenon joinery). I have sharpened the standard bits without gaining a marked improvement.

I read somewhere that the machines are only effective with really good quality bits so I started searching for information on decent quality bits to see if I can make some use of the machine. I find that Lee Valley sell some that are advertised as "premium" and the US sites vouch for the high quality of the Powermatic brand hollow chisels. There are also some super-expensive large hollow chisels made by Southern Tools in the US that have tungsten carbide tipped drills available. None of them seem to be available here so would need to be purchased from the US or Canada.

I believe that Carbatec sell some Taiwanese made hollow chisels that are meant to be better quality but they do not appear on their web site or catalogue and there is no information about the steel or sharpening of them.

Before I get carried away with purchasing any of the supposedly better hollow chisels I thought it would be wise to see if anyone on these forums has experience with these premium bits compared to the Chinese cheapies?

Comments welcome.

David

[ian]

hi David

Perhaps several issues there

do you have a set of cone sharpeners for your existing bits

they might make some difference to how the Chinese bits perform, though if the steel is rubbish or has lost it's temper, they are unlikely to make any difference.

2. are your mortise bits set up correctly? Does the auger extend the correct distance below the bit? When you say the bits are sharp, are they cut your fingers sharp?

3. are you trying to use too large a bit? Dad had a Jet morticer and even with sharp well set bits, it struggled with 1/2" mortices. 3/8" was it's comfortable maximum.

[Xanthorrhoeas]

Hi Ian,

1. The sharpener that I have is just a single ribbed/serrated edge steel cone, not the diamond sharpening cones as advertised by Lee Valley, which look like the ones that you show above.

2. In terms of set up my answer is maybe not. I have not been concentrating on the bit extension beyond the hollow chisel - what is the recommended amount? My mortiser came with zero instructions. And, no, I can't seem to get the bits razor/cut-the-fingers sharp - they feel "sharpish" but do not get better than that - may either be the steel or could well be my sharpening technique there as I usually sharpen blades (chisels etc.) with a wet grinder and can't use that for the hollow chisels.

3. Yes, most likely. from what you say I probably have unreasonable expectations of the Chinese generic machine in tough timbers like eucalypts. I have also read that it is better to use a much smaller chisel to start and chop out most of the waste, so perhaps should adopt that technique? I haven't done so as yet because of the accuracy/alignment issues I feared that it would create.

[Rod Gilbert]

Hi all,
I have a set of the Carba tec bits and have found them to be quite acceptable I have used all of the sizes and the 5/8" one into some very solid blue gum and worked well, i also have a sharpening set(also from carba tec) which includes a diamond plate for the outside flat faces and a centered counter sink type bit that has different size centre's for each size bit to keep it concentric when turned by hand to sharpen the inside of the bit. When setting up the chisel you lock the chisel with a spacer between the bit and the body something like the thickness of comercial veneer .6mm then push the bit in hard to the chisel and lock it then loosen the chisel(and remove the veneer) and push it home to the body to give the appropriate clearance for the drill. When using in difficult material I apply a touch of wax which melts on the chisel to help if it drags on the withdrawal. I couldn't find them easily on the new web site for carba tec it took some doing just to find the chisel set and I couldn't find the sharpening set so I would ring them to see if is available if interested.
Regards Rod.

[Xanthorrhoeas]

Hi Rod,

Is your set from Carbatec the five (I think) bit set in a wooden box? Those may be the Chinese set that look the same as the ones sold by H&F. Carbatec's new website does not list either those or the Taiwanese chisels but a very helpful fellow on their sales team told me that they do sell the Chinese five? piece set and also individual Taiwanese-made hollow chisels that he said are a cut above (or perhaps that should be a cut below since these are mortisers we are talking about).

If you are getting decent results from the Chinese hollow chisels it would indicate that I need to learn how to sharpen them better!

[Rod Gilbert]

Hi Xanthorrhoeas
Yes that is the set I have cut a lot of mortices with the 1/4" and 3/8" and some with the 5/8" and had good results with all of them. If you have a lathe you could turn a hardwood cone and use with grinding paste to hone the inside of the chisels and a rub on a stone to sharpen the square outside. If you use a smaller chisel to remove some timber first then you won't have a centre to locate the larger one I think that could be a problem.
regards Rod.

[rod1949]

Yes I'm in the same boat. I sort of detest using the machine cause the chisel/s get caught in the mortise (I've been told to rub a small diamond sharpener on the outside flats of the chisel to easy this problem, haven't done it yet but will do one day).
Back when Jesus was a boy the joinery shop I worked in had a chain mortise which worked a treat, but the old Joiner Bloke would put a chisel cut on each end of the proposed mortise to prevent breakout from the chain. My job as a young apprentice was cutting all the tenons (1000's of em) by hand... learnt to saw straight.

[China]

I have been using hollow mortise chisels and augers made by J.E.Morrison & Sons Sheffield England for 35 years in my opinion they are the best available I have never had any concerns what so ever, I have some that have cut thousands of mortises and still have plenty of life in them

[rod1949]

According to this https://www.thegazette.co.uk/notice/L-59467-1145737 they've closed up.

[ian]

Hi Ian,

1. The sharpener that I have is just a single ribbed/serrated edge steel cone, not the diamond sharpening cones as advertised by Lee Valley, which look like the ones that you show above.

2. In terms of set up my answer is maybe not. I have not been concentrating on the bit extension beyond the hollow chisel - what is the recommended amount? My mortiser came with zero instructions. And, no, I can't seem to get the bits razor/cut-the-fingers sharp - they feel "sharpish" but do not get better than that - may either be the steel or could well be my sharpening technique there as I usually sharpen blades (chisels etc.) with a wet grinder and can't use that for the hollow chisels.

If your definition of sharp is the edge off a wet grinder, your morticer chisels will be very blunt.
the hollow morticer chisels need to be sharp enough to easily pare end grain, as this is what the tool does. Touching the tips of the chisels should draw blood.


to add to what has already been posted, this Wood Workers Guild of America article might help How to Use a Mortiser

[Jeffen]

That's agreat link Ian,

I had worked out most I need to know about setup from youtube, but the point about always having the chisel cut with wood on either 2 or 4 sides I hadn't known,
makes a lot of sense.

On the original subject of bits, I bought a few from Amazon a while back, they were variable in quality, but the worst problem was on some the auger shaft was too short
and the chuck wouldn't grip them tightly enough so they would either spin, or ride up (removing the clearance between auger and chisel).

I ended up buying the carbatec set, and while nothing special, they are good value for money and do the job.

Regards, Jeff

[China]

rod1949 that is possible I have not purchased from them for a couple of years, probably should have checked before I posted

[jazzy69]

Hi David,
There is a video by Bob Van Dyke on the Fine Woodworking site about sharpening and set up. It is a free one too.
Regards,
Ross

[auscab]

I use the Carbatec boxed sets , I think they are pretty good . I always reduce the size of the chisel from about 5mm back from the cutting edge by running it over the front curved wheel of my linisher . The slightly smaller size makes a very big difference to the chisel sticking in the wood. It just stops it happening .
I don't know if it has been said yet , but I was told and have always ran the chisel with the open side of it emptying the dust into the newly created mortise, to the open side is to the left or right .If you have it open to the front or back and its having a harder time getting rid of dust on a deep plunge , every plunge . And that's not good for the temperature . Over heating kills the drill bit . That's what ends the life of mine . Ive re hardened and tempered chisels and bits with the oxy torch , it works well . I use a lot of US white oak , not much Aussie hard woods. In the odd very hard timbers and with the Oak , its the first plunge that can be the hardest , as you would know . so 5mm in and then a little to the right and another 5mm in , taking it down in steps . once your down to your depth then each plunge is only half a bite wide , do you do that ?
I very rarely sharpen chisels , I find its the drill that needs the touching up all the time . If I do touch up a chisel its usually with a pointed stick with sandpaper around the end or I also have an air powered die grinder and small ceramic balls or cones .
If the drill and inside of the chisel are getting gummed up with black hot tar like crap , soak them in a tin of Caustic , and rinse them .
Im not so sure the bench mounted ones are up to the job with the leverage . I used a drill press fitted with a set up 24 years back , that was hopeless . My smallest mortiser now is the old style Carbatec machine , the largest they sold twenty years back. The largest one I use is a Wadkin chain and chisel ,the MF. I run this mainly with the old chisels that came with it and use it with the chain, its quick !
I have paid more for chisels that come in a yellow and black box , were these from Carbatec as well ?? I think so . They didn't seem better than the boxed ones though .

Rob

[ian]

I use the Carbatec boxed sets , I think they are pretty good . I always reduce the size of the chisel from about 5mm back from the cutting edge by running it over the front curved wheel of my linisher . The slightly smaller size makes a very big difference to the chisel sticking in the wood. It just stops it happening .

great tip !!