Changing Jet Planer Knives

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CHANGING JET 13" PLANER/MOLDER JPM-13CS KNIFES

I purchased a Jet 13" Planer/Molder over seven (7) years ago and a set of special molding knives to form the radius on my turkey box call lids.  That planer/molder has gotten a serious workout, not only with turkey box call lids but some of my projects such as heirloom boxes, napkin holders, serving trays, hanging porch swing, banjo construction, etc., of which a good amount of the surface planing was on hard curly maple wood which takes a toll on dulling the planer knives very quickly.

Above is an internet stock photo of the Jet 2 in 1 planer/molder.

After looking at what a replacement set of planer knives for the Jet 13" planer cost, it was definitely cost effective to have them re-sharpened at this time; at least that was surmised.  I carried the knives to a a facility that specializes in sharpening saw blades of all types and of course planer knifes.  The turn around is around a week.

I did internet searching and found several companies offering replacement knives for the Jet 13 inch planer/molder and they priced in range from over 100 bucks directly from the Jet distributor to 39.95 for a set of Titan Knives.  There were cheaper knives, but when the shipping was factored in, the Titan Knives were the best bang for the buck.  I ordered a set of the Titan Knives from Oella Saw and Tool located in Elliott City, MD and the knives arrived on 04-12-17, which excellent quick service.

Below pixs taken of removing the knives from the planer/molder and a few narrative comments along the way.

SAFETY FIRST - DISCONNECT POWER SOURCE

Safety has to be first, therefore unplug the power cord to the machine.  If directly hard wired, flip the breaker switch to the off position and secure breaker panel where no one else can flip the breaker switch back to the on position.  This is mandatory in a work environment!

In order to remove the planer knives, there are three (3) hex socket head cap screws on top of the dust hood dust chute and three Phillips head screws on the rear of the dust chute.

After removing the three hex socket head cap screws and three Phillips head screws, the dust cover and chute can be removed by pulling the cover upward, allowing access to the cutterhead assembly which contains the three knives, long and short lock bars.

Exposed cutterhead assembly below.

With a marking pen, label each knife on the cutterhead one, two and three for easy identification.  I went ahead and labeled the lock bars for each knife also. 

Loosen all lock bar set screws on knife number one.  With the brass rod that is provided in the tool kit with the machine; using a mallet, carefully tap on each end of the outside of the set screws for all three lock bars on knife number one.  This loosens the taper fit of the lock bar.  Carefully remove knife.  Remove lock bars.  Clean all surfaces of the cutterhead, slot, gibs, locking bars, etc.

AUXILIARY PLATFORM 

The center short 2 inch length lock bar is for special molding of which the molding cutter knife will be at least 1/8 inch higher than the regular cutterhead knives and requires a special trough to be made to center the wood in line with the molding cutter knives.  Also, the in-feed and out-feed rollers have to be re-adjusted when using molding knives.  There is a lot of set-up involved to use the center slot for molding knives and a dedicated molding machine would be highly desirable.  With the molding knives in place, you are limited to the width of material you can plane and also you are limited to a 2 inch wide molding cutter which worked fine for my turkey box call lids since they were a little less than 2 inches in width.  I used the above machine mostly for making turkey box call lid radius cuts and did many years supply of the lids at one set-up before removing the special molding knives and trough/auxiliary platform.  I currently, use the planer just for surface planing instead of making box call lid radius cuts.

Below a pix of the auxiliary wood platform removed from the planer with a Eastern Red Cedar board that had been planed using the special set of radius knives in the molding cutterhead.

The little Jet 13 inch planer/molder did a great job cutting the radius for the turkey box call lids.

Above is pix of the cutterhead assembly with the knives and lock bars removed.

You repeat the above steps for knives two and three.

Above pix of the lock bars, brass rod, Allen wrench and the adjustment height tool for the cutterhead knives.

I will post pixs of installing the sharpened knives into the cutterhead when I receive them back from. 

INSTALLING REPLACEMENT KNIVES

I received the reground knives on 04-11-17 and was not impressed with the regrind.  The knives would definitely not shave any hair off my arm and only one knife would begin to cut a regular piece of paper.  I could see the knife edges and they were basically a little blunt.  Apparently, there was a two stage grinding done and the second final grind did not come to the edge of the knife to produce a razor edge, even though around a 40 degree angle and a little bit of a hollow ground instead of a flat ground was present on the knives.  Also, I put my calipers on the width of the blades and they varied from .618 to .625 which is not precision grinding in my book.  Although this is not a big issue, since each knife can be adjusted to Jet's standard using the set-up tool provided with the machine.  The regrind was a wasted $ 16.05 in my humble opinion, therefore I did not install the original Jet reground knives.  I am sure I could sharpen the dull knives on a flat surface using conventional techniques without any expensive equipment, but will chalk this one off to experience.  

Instead, I installed a replacement set of planer knives manufactured by Titan Knives and they were razor sharp.  Those knives were flat ground to an excellent smooth finish, whereas the original Jet knives were vertical ground which will leave a micro serrated edge since they appeared to be ground to about a rough 100 grit.

Click on the thumbnail pixs below for a larger screen view:

Below is a close-up pix of the back side of one the original Jet knives that came with the machine.  As evidenced by the rough vertical manufacturing grind lines, the knife edge will be somewhat serrated if viewed under magnification.  The original blades performed pretty good until they of course got dulled from usage over the years on very hard woods.  The planer hasn't been in much of a production environment as far as continued usage and the reason the knives lasted as long as they did.

The Titan Knives are precision made of T1 HSS with a smooth flat horizontal ground finish on all surfaces of the knifes with the grind lines running parallel to the length of the knife and to reiterate, razor sharp.

To install the knives, you place all the lock blocks in the cutterhead slot along with the spacers for the short molding lock bar for knife # 1.  The knife will rest on top of a portion of two flat head Allen head machine screws which are for adjusting the height of the knives.  You tighten each lock bar to take out the slack and using the height gauge for the knife; raise or lower the knife blade until it contacts the gauge, checking the knife height at both ends.  You could set up a dial indicator gauge and do the same thing with more precision if desired.

You then tighten all the set screws pulling the tapered lock bars tight against the knife and the cutterhead slot.

You do this for all three knives.  It was a little trouble keeping the knives flush against the height adjustment machine screws since the blades wanted to ride upward when tightening the locking bars.  I used a hammer and wood block to tap the knives tight against the machine screws when the knife would ride up off the flathead machine screws that control the knife height. 

After the knives were installed, the dust chute and dust cover was installed.  I will give the planer a test run before too much longer.  My next woodworking project is a potato and onion storage bin cabinet for the kitchen.

IN-FEED & OUT-FEED ROLLER ADJUSTMENTS

While waiting for the cutterhead knives to be re-sharpened, I adjusted the spring loaded feed rollers.  In essence, you want the spring loaded in-feed and out-feed rollers to be about 1/8 inch downward from the cutterhead which keeps adequate pressure onto the material you are planing, allowing the in-feed roller to pull the material into the cutterhead along with the out-feed roller to keep the material flat against the bed of the planer.   

When I first got the machine, I made three set-up blocks, however I could not locate them and made another set of two blocks only.  Below is an archived pix of the original set-up blocks:

Click on thumbnail pixs below for a larger screen view:

The purpose of the set-up blocks will position the in-feed and out-feed rollers as stated above in the proper relationship to the cutterhead.  Too little pressure and the board will not be pulled through the machine and if the feed rollers are too low, it will overload the machine and/or not allow you to feed the material into the machine.

As a general rule of thumb, the in-feed and out-feed rollers are set 1/8" below the cutterhead (not the knives).  Make certain the power to the machine is off!

Lower the work table to allow the  cutterhead block to slide freely between the table and the cutterhead.  NOTE:  Cutterhead may have to be turned by hand to rotate a knife out of the way....in this case, I already had the knives removed.

Adjust the table height so the cutterhead block can be inserted between the table and the cutterhead with minimum resistance.

Remove the cutterhead block.  Do not raise or lower the table at this point.  It will affect the final result.

Insert the block labeled "Feed Roller" into the planer opening.

Raise or lower the in-feed roller until it rests on top of the block end to end.  To adjust the in-feed roller, loosen the jam nut on both sides of the in-feed roller.  Turn the threaded bushing counter clockwise to raise the roller and clockwise to lower the roller.  Raise or lower the roller until it contacts the top of the block equally on both ends of the roller.  Block should be slide in and out with minimum of force.

Repeat the process with the out-feed roller. 

PRIOR MAINTENANCE

In the years using the above planer/molder, I have experienced only one equipment malfunction around March 2010 and that was brought about by taking to deep a cut off a wide board which had a tapered thickness.  Before I could cut the machine power off, the machine bogged down and one of the two chain drive sprockets broke along with shearing a keyway or two.  Those sprockets appear to be cast and/or Metal Injection Molding technology rather than machined from a billet of steel.  It didn't take too long to get replacement parts on line.  I ordered a couple spares of each, since the shipping was more than what the parts cost or close to the amount anyway.......don't remember exactly the amount of shipping, but it was very excessive.  Shipping and Handing charges are a big profit for some companies. 

Below pix of the spare parts:

Pix below of what the gear feed roller assembly looks like:

Web published by Bill aka Mickey Porter on 04-06-17.

WHAT IS PLANER SNIPE

Those that are senior citizens probably remember about going snipe hunting, either holding the bag or participating in the drive.  In a nutshell, an unsuspecting young person and maybe a little on the gullibility side, would agree to go snipe hunting which was after dark in some remote location.  The idea was to hold a burlap sack in a small creek bed and the party of several would go upstream and drive or flush the snipe down to where the person holding the bag would be able to catch him in the burlap sack.  Once the person holding the bag was at the proper location, the other party would actually leave and not return, leaving that person alone waiting on the snipe.....grin if you must!

Well, planer snipe is not that kind of snipe, but a malady common to the usage of a small planer and/or the bench top type of planer which leaves one or both ends of the planed board a little thinner than the rest of the board.  To some degree, snipe happens on much larger planers too but not as pronounced.  The effect is usually quite subtle, but if you run your fingers along the board, you can usually feel a slight step.  Shining a light on the board at a low angle also reveals it. Below is a pix screen captured from the internet showing what snipe looks like:

The principle cause of snipe is the unbalanced pressure exerted by the rubber rollers, which is normally experienced at both ends of the work piece.  When the work piece is introduced to the planer, the blades work on the piece while held by only one rubber roller (in-feed) which pulls the board upward slightly, after which it is held by two rubber rollers (in-feed and out-feed) and thus equal pressure at both ends of the work piece. This ensures that a uniform surface is realized after the nearly invisible groove.  In contrast, at the out-feed, a situation arises when wood is held by only one rubber roller and hence unbalanced pressure which ultimately results into a planer snipe. 

GETTING RIDE OF PLANER SNIPE

It is possible to eliminate or reduce the planer snipe by applying upward pressure on the end of the board once the in-feed roller contacts the board holding the work piece firmly on the table during the in- feed and when the board is about to exit the cutterhead.  Alternatively, use a discarded piece of wood in front of the actual work piece so that it takes the brunt of snipe at both ends. This method always works, but applying upward pressure works fine in my humble opinion.

Snipe can be sanded out in most cases, but it is best to eliminate it altogether.  In the past, if snipe was a little too deep to sand out and there was spare material, I simply cut the end portion off of the material that had the snipe, but that is a wasteful, when you are frugal and using "high dollar" wood.

JET PLANER/MOLDER PERFORMANCE

For the money, this has been an excellent 13 inch planer/molder and would recommend this machine to anyone that needs a planer with a little more power than the bench top models.  It will work in a semi-production environment for a small shop, but a larger cabinet shop would need a much larger and more powerful machine.  Most of these types of machines are no longer manufactured in the USA, whereas Delta, Powermatic, DeWalt, Craftsman, etc. were once manufactured here in the USA and high quality machines.  A Grizzly planer is a comparable machine to the Jet brand.  Most of the time, you get what you pay for!

It is sad, the Cooperate Greed of America has sent many of our manufacturing jobs to foreign countries for the sake of the all mighty dollar!  See scriptures below.

Web published updates by Bill aka Mickey Porter on 04-09-17 and updated on 04-12-17.

LEAVING ON A SPIRITUAL NOTE

1 Timothy 6:10  “For the love of money is the root of all evil: which while some coveted after, they have erred from the faith, and pierced themselves through with many sorrows.”

John 6:44  “No man can come to me, except the Father which hath sent me draw him: and I will raise him up at the last day.”

John 3:16 - 3:18

16 For God so loved the world, that he gave his only begotten Son, that whosoever believeth in him should not perish, but have everlasting life.

17 For God sent not his Son into the world to condemn the world; but that the world through him might be saved.

18 He that believeth on him is not condemned: but he that believeth not is condemned already, because he hath not believed in the name of the only begotten Son of God.

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