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Thread: Jet JJP-12 Helical Head Conversion Documented

  1. #1

    Jet JJP-12 Helical Head Conversion Documented

    When I bought my JJP-12 it was on sale for $1599, no tax, no shipping. I couldnít justify the then $2800 for the helical cutter head at that time. I had been using straight knives for years and survived. Well, after loads of lumber, countless hours of setting the knives, and tear-out on various machines I decided to investigate a swap out for the helical head. Much to my surprise, I could get a new cutter head, with all the inserts and two brand new bearings for under $700 right from Jetís website. That would make the total cost of my JJP-12 just $2294 for the HH model. Ok, not quiteÖthe feed rate on the HH is only 12 fpm and it is 20 fpm on the non-HH model. That doesnít worry me too much but I did find that for another $120 or so I could change out the gears and get mine to 12 fpm if I really needed it. I was shocked when just 4 or 5 days later my new helical head arrived. Those nice guys at Jet even through in a box of spare cutters, a bag of extra cutter screws, and two T25 screw drivers. I searched all over the internet for set by step instructions on how to swap this thing over and didnít find any. I found a few others had made the switch with super results, but no pictures or anything. So, I thought I would write up the steps I took and post the pictures of my procedure for others who might be worried that they canít manage this conversion on their own. These are not instructions; I am just sharing my experience. If you donít think you can do it after you read about my experiences, then donít do it.

    First, I cleared a large table and moved it right next to my JJP-12. I laid some paper down on the top to put the parts on. The paper lets me move groups of things all together if I need to and lets me write notes, measurements, or draw diagrams right where the parts are lying. It works for me. I unplugged the power, removed the fence, and the guard arm assembly. I also removed the back panel to expose the motor and belts. Then, I lifted the tables and removed the spring loaded pin that holds the dust shoot down in Planer mode. Watch out that it doesnít shoot out of the hole. There is not much tension, but enough to lose a small spring. I took out the two screws that hold the front bearing cover on and removed the cover to expose the front bearing.

    Then, I put the tables back down and removed the rear belt and pulley guard cover. From there I loosened the four motor mount bolds and slid the motor up and to the left. It sure was nice of Jet to think about this little but super useful feature. The motor sits there happily out of the way while you easily remove the belt. The upper pulley, on the cutter shaft, is keyed, so be careful when you loosen the two Allen screws that hold the pulley on. Slide the pulley off and catch the key before it bounces off into never land. By the way, if you notice that the chain that drives the feed rollers for the planer is dragging on the cutter head shaft, donít worry about it. When the drive system is engaged, the chain will lose all of its slack and lift off of the shaft. Donít ask how I know this.

    I then removed the blades from the cutter head. I decided that I didnít want to try and muscle the head around with three razors in the way. My little finger on my left hand knows all too well how sharp those suckers really are. But thatís a different story. The front bearing housing is going to have to come off; there is no other way around it. Those two large Allen screws on top of the housing are holding some pretty stout looking springs down. It was with great care that I slowly turned the first one only to find out there is no real pressure on them. Not even enough to make them pop up once it has been backed out all the way. I removed the Allen screws and the springs. I counted the number of full rotations on the Allen screws so I could put them back exactly where they came from. Turns out, they were both 4 Ĺ turns. Then, I removed the two small Allen screws that hold the cross bar on the right and the cross bar with the anti-kickback paws on the left to the housing. The dust hood just slides in, no screws.

    Now for the real fun. I cannot stress this enough, spend the $25 on a pair of good quality ring pliers. I bought the cheapest POS I could find and it made the job impossible. I ended up going back and getting the nice pair and WHAT A DIFFERENCE! The cheep ones would not stay in the holes so the ring kept popping off and going back into the retainer slot. Now is also the time to tie your dust hood in the vertical position so it is half way between its two modes. I used a small bungee cord and hooked it to the top. It will be in the way when you try to remove the cutter head if you donít prop it in this way. One more thing, I put a blanket on the planer table to protect anything that might fall as I started to pull things apart.

    The first step to removing the cutter head itself is to remove the spring clamp or ring clamp. I used the high quality ring pliers to squeeze the ring together and pull it out of the retaining slot. Directly behind that is a flat ring and then a bent ring that acts like a spring. Mine did not shoot out; they just sat there and waited for me to pull them out. I went to the back and did the exact same thing there. It is slightly more difficult because the shaft sticks out (for the pulley) and the chain for the drive system is hanging there. It still isnít difficult if you use high quality ring pliers. Hint, hint. I measured the distance from the edge of the housing to the bearing on both the front and back. They were not exactly the same, but very close. Then I tapped on the end of the shaft from the front of the machine with a small piece of wood and a hammer. As I did this, the entire cutter head slowly moved backwards. When the front bearing was halfway out of the bearing housing, I removed the two large bolts that hold the housing to the top. Before I did this, I ran a pencil all the way around the housing so I would know exactly where it was when I started. I started pulling the housing toward me and took my time to carefully remove each part that was connected to the housing one at a time. In no time, the front housing was free and out of the way.

    I slipped a piece of plywood under the shafts so they wouldnít sag. I went around back and tapped on the shaft with the wood and hammer until the rear bearing was just beginning to protrude from the housing. Then, the big moment, I pulled on the shaft very slowly until it was free from the machine. I laid it on one of my benches next to the new one just to make sure everything looked the same. Other than the cutters, it did! I decided not to pull the old bearings off of the old cutter head because they are cheap and stuck on the shaft. Now I will have new bearings in my machine. I left the foam on the new cutter head because it was loaded with knives and I didnít want anyone to get hurt while pressing the bearings on the shaft. I made up my mind from the very start that I was not going to even fuss with trying to press those bearings on myself. I donít have the equipment needed. I called a local machine shop and the guy said it would be between $15 and $40 dollars to press the new ones on depending on how complex the job was. When I got there, he took the cutter head and bearings out on the floor. In 5 minutes he returned with the whole thing put together and said, ďHow does $5 sound?Ē Best $5 I spent on this project!!
    I noticed in the manual that Jet recommends a 30 amp circuit breaker, socket, and plug for this machine. So, I stopped at the box store and picked up a new socket and plug, but my circuit breaker is already 30 amps. While I was at it, I decided to pick up one of those low vibration link belts for thing. I got home and did the electrical swap out and took out about 4 links of the belt.

    Installation is pretty much reverse of the dismantle process. Just make sure that you put all of the pieces back into the holes and slots on the front bearing housing before you tighten everything down or you will spend an extra 30 minutes unbolting it all to put that one piece back in. Did you know that the dust hood has a small piece that is separate from the main hood and sits in a slot in each bearing housing? I do now! I got everything except the cutter guard and the fence back together, and then stopped. It was time to plug it in and hit the magic green button. I could not believe how quiet my usually loud JJP-12 was. NICE! I think the hardest thing about this entire job was realigning the tables once it was all back together. We all know that this is the most finicky part of the JJP.
    Attached Images Attached Images

  2. #2
    Had to add the rest of the pictures in a second upload. The blue pliers are the high end and the yellow ones are the POS. I have not finished adjusting the tables yet, but will do that tomorrow and give her a test drive then. I will let you know how that goes.


  3. #3
    Is there a Helical Cutter Head system for the Jet 13 inch Planer-Molder ?

  4. #4
    Clarence, Not sure if they make one for that model or not. You can look on the Jet website and find out.

  5. #5
    Just checked the Grizzly website. They have a spiral cutterhead for the 6 inch jointer . Wonder if that could somehow fit the Craftsman 6 1/8 inch jointer ?

  6. #6
    Join Date
    Dec 2004
    Richmond, TX
    Check with Grizzly to see if they have a cross reference chart to see what other brands it might fit. Alot of these machines are made by GeeTech and privated labeled for other companies.

  7. #7
    Nice post David-thanks for sharing. I've had this conversion on my bucket list for some time now, having even made a list of all the parts I would need from Jet to slow the feed rate. However, I had never bothered to price the Jet head. Just a question-can you tell if the Jet head is a Byrd or is it from somewhere else?

  8. #8
    Join Date
    Dec 2007
    David, I see you are running a link belt on your machine. I was under the assumption that link belt was only rated for 1.5 hp.

  9. #9
    I just completed my first cuts in jointer mode with the new head. I am happy to report it is pure joy to use. Smooth operation, quiet, and excellent results. Like others have said before, it feels like its pulling the wood down, but not to the point that it affects my ability to slide the wood over the head. With the straight blades, I always felt like they were bouncing the wood up and down on the top. I know that sounds dramatic, but I always wondered how it could cut the face flat and smooth if it was smacking the wood like that. This new cutter head is just awesome.

    Greg, I looked all over the head and I can't tell. There are no markings on this cutter head. Its black and has a slight texture to it. I will take a few close up shots of it and post it here later today. I will also get to the planer mode as soon as possible so you can see the results at 20 fpm.

    Joe, I have searched everywhere for anything that states the belt is only rated for 1.5 hp and can't find anything to back that up. The Power twist website states that it is designed to outperform the standard v belt. Never mentions anything about maximum hp rating. I have made a few passes with it and its working great. If it starts to give me problems, I will post it here.

  10. #10
    Here are some pictures of the cutter head, results from using the jointer, and results from using the planer. I used ambrosia maple for the test. There was no bogging of the motor at all in either the jointer or planer mode. The results are seriously stunning. If you have any question about the worth of swapping to a helical head, let me tell you it is worth every penny!

    Edge with new headAfter Edge.jpg Same edge with old straight knivesBefore Edge.jpg
    Close Up of cuttersCutters close.jpg Close up of cutter headCutters.jpg
    Results of planer at 20 fpm. It looks like glass to me. It feels super smooth.Planer Face.jpg

  11. #11
    Join Date
    Feb 2003
    Doylestown, PA
    Quote Originally Posted by Clarence Martin View Post
    Is there a Helical Cutter Head system for the Jet 13 inch Planer-Molder ?
    I don't know for sure but I doubt it. Helical molding knives would be impractical if not impossible.

  12. #12
    I have not tried running it as a molder, just use it for regular planing of lumber.

  13. Dude, you did one hell of a great job writing this up. I was able to swap out my 12 straight blade to the HH using your directions. Awesome job.

  14. #14
    Join Date
    Jul 2003
    Trussville, AL
    Thanks reviving this. I'd like to do the same hopefully next year.

  15. #15
    Join Date
    Oct 2005
    Pasadino, CA
    So worth it on a J/P !

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