Question about Mortising Machine and Bits

[LCHIEN]

Yes, Loring and I are still friends, no worries there.

But at the risk of needlessly flogging a thoroughly dead horse, I do have to say that I don't understand his continuing insistence that there are only two sizes of chisel shanks, 5/8" and 3/4". The larger Powermatic mortisers (and there may be other brands too, I don't know) will accept either a 5/8", 3/4", or 1-1/8" bushing. His JET mortiser came with the smallest two sizes of these; the big Powermatic comes with all three. The small benchtop mortisers like his JET mortiser or my Delta may not accept a 1-1/8" shank chisel, but the issue, raised by Loring himself, is the available sizes of chisels. As he himself has stated at least twice, the chisel manufacturers don't always specify (at least in a way that is easy to find) what size shanks their chisels have. My point is that the size choices are not limited to just two: there are at least three.

My error, for which I apologize, was in assuming, incorrectly I now realize, that the chisel shank size was a function of the chisel's cutting size, rather than being differering standards as Loring has explained. This assumption stems in part from reading a comparison test of six or eight benchtop mortisers. I don't recall all of the brands included in the test but I do know that it included both Deltas, the JET, the tilting-head General, the Fisch, and a couple-three others. I remember reading that in order to more accurately gauge the relative performance of the various machines, the tester/author used the same chisel in all of them, to eliminate the variable of this chisel itself. Since this same chisel had to be installed into every machine tested, and since my Delta mortiser comes with 5/8" shank chisels, I made the assumption that this was the typically-supplied size for these benchtop machines. Perhaps it is, perhaps it isn't: at this point, I still don't know. (Loring, your JET came with both size bushings, but what size are the chisels themselves?)

I made this qualification at one point (one can't belabor small things too much or the posts get too long and no one reads them)

I do know there are two sizes in common use on benchtop sized machines (the big powermatic does not count!) - 5/8 and 3/4"

My jet (and my Delta Mortising attachment which I have since recycled) both came with 1/4, 3/8, 5/16 and 1/2" square mortise chisels. The Delta chisels had 5/8" shanks (this I'm assuming from the recent research) and the Delta arch attachment that held the chisels only had one bushing.

The Jet, I'm not sure which shank size the supplied chisels came with. I'm thinking they must have been 5/8" because I used one of the chisels from the Delta w/o having to change the bushing, I seem to remember. I might be able to check tonite.

I do remember quite clearly when researching mortisers that this issue came up and at the time it was not clear if the jet would be able to use chisels I already had (because I knew there were different sized shanks) and I was very relieved to find (after I got it) that the Jet would take both with the supplied adapter. I had looked up countless chisels available on the internet, I found enough examples listing 5/8 and 3/4" shanks to know that there were at least two sizes and also found that about 75% of the manufacturers or sales websites simply did not post the shank size.

I do actually own a 3/4" square chisel (with a shank that fits my Jet) but I have not (pick 1) A) been brave enough or B) found the time or C) had a project that called for this size chisel.

[Tom Miller]

Chisel shanks come in different sizes???








Regards,
Tom
Ignorance is...uhhh, golden?

[mschrank]

FWIW-The upcoming issue of Woodworking magazine will feature articles on mortises and chisels (the kind that are used in mortising machines as well as hand):

http://www.woodworking-magazine.com/...f3a0530b3.aspx

[LCHIEN]

Chisel shanks come in different sizes???



Regards,
Tom
Ignorance is...uhhh, golden?

bliss, tom, it's bliss.
you're thinking silence.