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Saving A Jet JWP-15CS From Dump #16: Installing knives and "trying" to align

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Blog entry by Holbs posted 05-06-2015 05:29 AM 1640 reads 0 times favorited 10 comments Add to Favorites Watch
« Part 15: First Run Part 16 of Saving A Jet JWP-15CS From Dump series Part 17: Nearing The End »

Came time to install the 3 knives. Thanks to the LJ forum for suggesting a 0.055” height of the knives from the cutterhead. I have a pair of the MLCS Jointer Planer Knife Setting Jig I found at an auction for $5. They work “initially” until it comes time to tighten the blade retaining bar. Then, the knives move between 0.005-0.0020 at that point. The MLCS jigs will work to get a rough dimension, and that’s about it. So out comes the dual magnetic base dial indicators which give the 0.001 precision. Working on 15” knives is 2x’s the frustration of working on 6” jointer knives. I have the outside of the knives set at 0.055” and thought I was all done. Nooooo’s…. the middle area is as high as 0.060. Called it a night and will retry tomorrow.

-- Yes, my profile picture is of a Carpenter Bee! The name is derived from the Ancient Greek "wood-cutter"



10 comments so far

View JoeinGa's profile

JoeinGa

7479 posts in 1468 days


#1 posted 05-06-2015 11:50 AM

If BOTH outside edges are at 0.055” and the MIDDLE is at 0.060”, then I’d suspect that EITHER the knives are bent … OR when they were sharpened, they were ground with an arc

-- Perform A Random Act Of Kindness Today ... Pay It Forward

View Holbs's profile

Holbs

1371 posts in 1490 days


#2 posted 05-06-2015 01:21 PM

Joe.. they could be bent or sharpened with an arc. But I’ll try again later today by using the MLCS planer jigs to set the blade 0.0020+ high and work 1 jib bolt from right to left at a time. I only did the end jib bolts (a total of 5).

-- Yes, my profile picture is of a Carpenter Bee! The name is derived from the Ancient Greek "wood-cutter"

View gfadvm's profile

gfadvm

14940 posts in 2151 days


#3 posted 05-06-2015 02:06 PM

A straight edge should answer the bent/ground unevenly question. I didn’t use dial indicators when I changed my 18” blades but I did start tightening in the middle and worked my way out. Not sure how important getting the blades absolutely perfect is as all your wood will get sanded after planing.

You are almost there! Thanks for taking us along.

-- " I'll try to be nicer, if you'll try to be smarter" gfadvm

View TheFridge's profile

TheFridge

5764 posts in 947 days


#4 posted 05-06-2015 04:22 PM

on my 8” jointer, I keep the gib screws on the low points tight and just snug the high points good enough to hold it as I tap it down with a block of wood and tighten it. If you go too far just loosen it and start over.

-- Shooting down the walls of heartache. Bang bang. I am. The warrior.

View Dutchy's profile

Dutchy

2012 posts in 1629 days


#5 posted 05-06-2015 06:12 PM

I have seen a lot of planer knives and a lot of them are as JoeinGa says with an arc. You can control this by putting two knives at your window glass with both sharpe sides against each other. The light will show you if there is an arc. I bet there is.

-- My englisch is bad but how is your dutch?

View Holbs's profile

Holbs

1371 posts in 1490 days


#6 posted 05-06-2015 11:52 PM

I think my procedure of installing 15” knives is faulty. I’m treating them like 6” jointer knives: such a short distance that I can just work on the end points. I’ll try the ‘ol Bob Vaughn method of sitting the blade 0.0020+ high all the way across, snug the jib bolts slightly, and work 1 jib bolt tightening and measuring at a time, then move to next jib bolt.
Of course, I’ll pull the knives out to re-start anyways and then I will check for flatness across the 15” on my 24”x24” granite engineer plate (again, another $5 auction item I picked up). IF there is an arc, does it matter of being off 0.005” or so?

-- Yes, my profile picture is of a Carpenter Bee! The name is derived from the Ancient Greek "wood-cutter"

View pintodeluxe's profile

pintodeluxe

4853 posts in 2274 days


#7 posted 05-07-2015 12:19 AM

Wow, this discussion sure makes me appreciate helical cutterheads with carbide inserts. I still have a three knife cutterhead on my jointer, but I upgraded my planer to a shelix, and have been very glad I did.

Good luck with the fine tuning.

-- Willie, Washington "If You Choose Not To Decide, You Still Have Made a Choice" - Rush

View Holbs's profile

Holbs

1371 posts in 1490 days


#8 posted 05-07-2015 12:22 AM

Pint… sadly, i’m a hobbyist. If I go pro or get really really serious, i will get the $$$ and go shelix route. I have plans to but I still consider myself in the learning stage. Have not even YET hand planed a single board.

-- Yes, my profile picture is of a Carpenter Bee! The name is derived from the Ancient Greek "wood-cutter"

View TheFridge's profile

TheFridge

5764 posts in 947 days


#9 posted 05-07-2015 12:38 AM

The knives will flex easily enough even if ground in an arc. Have never had a perfect set of knives after gettin them resharpened.

-- Shooting down the walls of heartache. Bang bang. I am. The warrior.

View playingwithmywood's profile

playingwithmywood

247 posts in 1058 days


#10 posted 05-07-2015 05:17 AM



Pint… sadly, i m a hobbyist. If I go pro or get really really serious, i will get the $$$ and go shelix route. I have plans to but I still consider myself in the learning stage. Have not even YET hand planed a single board.

- Holbs

with the carbide cutters lasting longer and then having 4 sides for me the hobbyist i figured it has been the cost savings but then I put mine in a dewalt 735 since i am stuck with 110 volt tools

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