Help! Craftsman 4 3/8" Jointer Knives

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Forum topic by Brad posted 08-08-2008 08:25 AM 6429 views 0 times favorited 8 replies Add to Favorites Watch
View Brad's profile


129 posts in 3769 days

08-08-2008 08:25 AM

Topic tags/keywords: planer jointer blade joining sharpening

I have had an old tarnished Craftsman 4 3/8” jointer sitting in the corner of my shop for awhile. Well last week i decided to restore it. Everything for the most part is in great shape after dismantling, polishing, and lubing. However I’m having a hard time deciding what to do about the jointer knives. I use the scary sharp system for hand plane blades but what about jointer knives?


Just for fun here is the model number 103.21820

-- Brad --

8 replies so far

View Silverdollar's profile


1 post in 3574 days

#1 posted 08-08-2008 06:39 PM


I have the same jointer that i have used in rebuildiing a cottage – the motor failed and it has no markings as to RPM. I am runinng a 5 1/2” drive pulley to a 2” arbor pulley – if saimilar to yours, what speed motor do you have – Sears has not been a help!! Thanks.


View Alex Lane's profile

Alex Lane

508 posts in 3886 days

#2 posted 08-08-2008 07:27 PM

I have an ancient Power King 4” jointer. The motor is a newer (circa 1970) 1.5HP GE motor that is 1725 RPM at full load. The motor to cutterhead speed ratio is approximately 2:1.

As for sharpening, that’s a difficult task unless you happen to have a JET or Tormek grinder, or one of those Delta-style grinders with the horizontally rotating wheel.

I would recommend the Scary-Sharp system, which is wet/dry sandpaper attached to a piece of float glass. With some practice I think you could get the hang of sharpening the jointer knife by hand using this method. Unless you have a chipped edge, Don’t worry too much about the primary bevel. Concentrate on honing the secondary bevel and maybe even a tertiary (3rd) bevel like David Charlesworth does with handplane blades.

I haven’t been so bold as to sharpen my knives yet. I just buffed the surface rust off of them with a wire brush and they seemed to still be holding quite an edge, even after 60+ years of use/storage!! They made things to last back then, that’s for sure.

When the time comes to sharpen my knives, I will either send them to a professional grinding service (where they will charge around $25 for the job), take them to the local community college’s machine shop and surface grind them, or I will try out the Scary Sharp method.

I fear there is no other way to get out of this inexpensively. There are several machines made for just this task, but they run $200 to $400 or more!! Maybe that would be a wise investment, but right now, I’d rather spend that kind of cash on some exotic wood or a Leigh Jig or something.

I actually only use my little jointer to “rough in” really wavy edges on boards. I use a jointer plane to put a final flat surface on the edge.


-- Lane Custom Guitars and Basses

View Brad's profile


129 posts in 3769 days

#3 posted 08-08-2008 07:51 PM

Silver dollar shoot me your email address because i have the original product manuel I can send you and it details what type of motor is needed and what rpm is recommended.

- Brad

-- Brad --

View jcecil's profile


40 posts in 3646 days

#4 posted 08-08-2008 08:54 PM

look at the post from GarageWoodWorks. Looks like he has a pretty simple solution for using sandpaper to sharpen them. I have also seen people take a board and cut the angle (25 degrees or whatever you want them sharpened to) on the long edge of it and do it that way.

View Brad's profile


129 posts in 3769 days

#5 posted 08-09-2008 07:40 PM

So last night i grabbed a beer and some cashews and spent some quality time with the jointer blades, some good classic rock and my scary sharp system. It worked well. The hone on the blades were sharp enough to cut my hands without even knowing untill about an hour later when i noticed a bunch of shallow cuts running across my thumbs.

I also pulled all the guts out of the motor and replaced the old cloth electrical lines with brand new wires. The motor runs strong even after probably 50 years!

Tomorrow after i pick up a new V-link belt and dial it all in we’ll see how it runs. When I’m done I’ll toss up some pictures.

- brad

-- Brad --

View Alex Lane's profile

Alex Lane

508 posts in 3886 days

#6 posted 08-09-2008 08:18 PM

Good Job!!!!

-- Lane Custom Guitars and Basses

View SCOTSMAN's profile


5849 posts in 3581 days

#7 posted 08-09-2008 08:23 PM

I have a double tormek system both sizes and a horizontal wet grinder too specially built for planer blades.But my favourite sharpenner is a sixteen inch wheel that turns horizontally with an oils pump which floods the bade and keeps everything cool believe me this makes a great finish.I need to make alterations to get it to accept planer blades as it is originally set up for chisels and planer blades.It works great.Alistair

-- excuse my typing as I have a form of parkinsons disease

View 6PTsocket's profile


17 posts in 1020 days

#8 posted 08-15-2015 04:21 AM

I have a 103-21821 that appears to be almost identical. The original motor that came with mine was a Craftsman 1/3HP 1750 RPM Split phase (start winding,centrifugal switch but no starting capacitor). The motor pulley is 5” and the pulley on the cutter head is 2”. The manual recommends 1/3 HP for general use and 1/2 HP for heavy duty use. There is a Vintage Machinery site that has your owners manual.

I need some information too. There is a hinged bracket that prevents the middle of the fence from deflecting. The bracket is slotted and a knob on an angled rod that is screwed to the side of the jointer locks the bracket after you position the fence. My fence has the number 29227-103 on the casting. From the parts list I know that the 2 screws that hold the bracket to the fence are 10-24 thread. I have the knob assembly but for some strange reason my fence was never drilled or tapped. I see from your photo that yours is drilled. I need the locations of the two tapped holes from the top and center to center. There are also two holes drilled in the fence which I assume are for a high auxiliary fence. What size are they, are they tapped, and where are they located measuring from screw centers to the top of the fence and from one end or the other. Do you have the hinged bracket? I have to fabricate one so I can use as many dimensions as you can get off of it like the length of the slot, length of the long and short leg,width etc. Thanks, I really appreciate any help you can give me.

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