Mortiser questions

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Forum topic by Purrmaster posted 06-14-2013 10:35 AM 963 views 0 times favorited 9 replies Add to Favorites Watch
View Purrmaster's profile


915 posts in 2118 days

06-14-2013 10:35 AM

Topic tags/keywords: mortiser mortising mortise


I just got my first mortiser. The Delta 14-651 bench top model. Initial impressions are generally favorable but I have a few questions. Since this is my first mortising machine I’m pretty green.

Is there an industry standard size for mortiser chisels? In other words, can I get replacement chisels from any manufacturer or do I have to stick with Delta’s chisels? I’ve heard good things about Lee Valley’s hollow chisels.

How clean should the sides of the mortise be? The sides of the mortises I’ve test drilled aren’t as clean as I’d like.

Which leads me to my next question which is how do I sharpen these hollow chisels? I don’t think the chisels are sharp enough out of the box. I’m not really surprised. I’ve never gotten an edged tool that didn’t need at least a little honing by the user.

Once I’ve worked with the thing for a while I’ll post a review.

Thank you.

9 replies so far

View Handtooler's profile


1577 posts in 2158 days

#1 posted 06-14-2013 10:54 AM

Although I don’t own my first, I’ve seen a couple or three u-tube videos on sharpening and setting up the chisels; Shopp Smith for one. They point out that setting the chisel’s advancement ahead of the chisel by a dime’s thickness is important. The videos use a conical slip oil stone for sharpening the inside edge and say dont touch the outside.

I think all company’s chisels fit other company’s machine’s clamping devices even the metric ones into the English sizes, but I may be wrong. And depending on the power of your machine effects the cleanness that you may expect from chisels larger than about 1/2-5-8”.

-- Russell Pitner Hixson, TN 37343

View MisterBill's profile


411 posts in 2277 days

#2 posted 06-14-2013 11:34 AM

Buy one of these or something similar for sharpening your chisels.

Russell has given you some good advice. I agree, don’t attempt to sharpen the outside of your chisels as this will eventually reduce the size (width) of the mortises that you are making.

View Purrmaster's profile


915 posts in 2118 days

#3 posted 06-14-2013 12:49 PM

I was thinking of trying to polish sharpen the outside edges of the chisel. The machining isn’t terribly smooth and the outside is part of the cutting edge. I’d probably go after the sides starting with 600 grit sandpaper and work up to 2,000. Would that be harsh enough to screw up the chisel width?

Has anyone used the Lee Valley chisels and bits? I was thinking of getting one of them to try it out but they’re kind of spendy. If I can fix the chisels that came with the machine so much the better.

This machine is a 1/2 horsepower machine. Not very beefy but the 3/4 horse machines were outside of my price range.

The reason I’m focusing on the chisels is because the sections where the drill bit goes in are fine. It’s the walls of the mortise that aren’t too great. I have to clean them up a bit with a hand chisel. Which isn’t the end of the world but does kind of defeat the purpose of having the machine in the first place.

I also considered trying to lap the table of the thing. The machining on the table is very rough. But I’m afraid I’d do more harm than good. Plus it would take forever.

View waho6o9's profile


8207 posts in 2602 days

#4 posted 06-14-2013 12:58 PM

View jusfine's profile


2422 posts in 2951 days

#5 posted 06-14-2013 02:39 PM

I have a larger machine, and find I do have to refine the inside of the mortises with a chisel or float from time to time depending on the species worked.

In my opinion, the key purpose of the machine is to eliminate the bulk of the work.

All the Best!

-- Randy "You are judged as much by the questions you ask as the answers you give..."

View Purrmaster's profile


915 posts in 2118 days

#6 posted 06-15-2013 08:50 AM

I feel like an idiot asking this but… what is a float?

View waho6o9's profile


8207 posts in 2602 days

#7 posted 06-15-2013 12:38 PM

Here ya go

View Purrmaster's profile


915 posts in 2118 days

#8 posted 06-16-2013 03:27 AM

Ah, I see. Thanks.

I’m pretty sure the sides of these chisels are going to need some polishing. The machining on them is rough and the chisel is sticking. Anyone use those Rockler diamond cones for sharpening the inside? I think the machine has enough horsepower. The chisels need some work.

View rockindavan's profile


299 posts in 2661 days

#9 posted 06-16-2013 07:59 PM

The outsides are going to need an initial sharpening, but after that all you have to do is a pass or two on a 8000 grit stone to take off the burr from sharpening the cone.

I have a powermatic benchtop, and it also doesn’t cut as cleanly as I like, compared to a horizontal mortiser. A few swipes with a chisel and they are more than adequate. Realistically the wall roughness really does not have a big impact on the joint strength, unless if it is really ratty, or too loose.

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