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Jet 6" JJ6 Jointer #4: two steps forward one step back

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Blog entry by Camper posted 10-13-2010 03:58 AM 1245 reads 0 times favorited 3 comments Add to Favorites Watch
« Part 3: hunt for the knife set screws Part 4 of Jet 6" JJ6 Jointer series Part 5: finally its all in one piece and ready for making saw dust »

it has been a while since the last update and in the meantime I was able to clean up the jointer real good and figure out what knob does what. I will post some pictures when its up and running, probably the next blog entry.

More importantly I was able to find some screws!!! I ended up ordering screws for the new jet 6” jointer after looking around all over the place without much luck. Figured if anything is going to fit, these would be it. Well they arrived today and their thread and size fit perfectly. I was real excited and started setting the knives. Of course this was too good to be true and I come to find out that, the head of the screw, though the right size, its TOO THICK and would not fit in the slot in the cutter head.

This is where i need some help. I started sanding down the heads of the screws to match the thickness of the head of the old screws. I can sand them down enough to fit in the slot. Thats good news I guess.

In the picture below, you can see one of the new screws sanded down on the top left (square heads are new screws and hex heads are old screws), and old screw next to it and in the gib below 3 new screws and an old one. Have several questions as follows:

1. Old screws have a flat top and the new ones sort of come to a rounded peak in the center. when I sand them down would it make sense to leave a rounded peak like the new ones of sand them down flat like the old ones? They are butting up against a flat surface inside the grove in the cutterhead. To me it seems like the larger the contact area, the better the grip…

2. I am slightly concerned regarding the safety of all this as these are after all holding newly sharpened blades spinning at a very high rate. I do not want to think about what could happen if one was to fly out of the cutterhead. Do you think this is a concern since I am modding these screws?

3. Following up on question 2, I have to use 5 new screws. Should I divide them up evenly between the three cutters like 2-2-1 so that there is at least 2 old screws holding down each blade?

4. Or am I being too paranoid and this is a simple and safe design where the pressure applied by the screws is so high that the once they are tight in the slot in the cutterhead the blades are going nowhere.

Thank you for reading and your advice and I understand the disclaimer that I do whatever I do at my own risk :). I am planning on setting the knives first thing tomorrow morning so any advice you can give me would be great help.

-- Tampa-FL



3 comments so far

View mrg's profile

mrg

536 posts in 1753 days


#1 posted 10-13-2010 05:56 AM

I don’t tjhink you need to mix the screws, but are you going to be able to turn them since they are square. They look like they won’t clear the bottom.

-- mrg

View Camper's profile

Camper

232 posts in 1610 days


#2 posted 10-13-2010 05:41 PM

it works!!! Finally!!!

mrg…you had me worried for a sec but the screws cleared the bottom w/o problem.

-- Tampa-FL

View Lee Barker's profile

Lee Barker

2169 posts in 1604 days


#3 posted 10-13-2010 05:50 PM

I have had square headed screws on jointers and it seem to work fine. I would like to see the heads flattened. Everything will be better.

I would drive all three new ones into a gib, down snug, and clamp the gib in a vise and file all three at the same time.

Yes, your perception of what is happening when the machine is running is correct, but there is lots of good metal to metal contact there. Don’t let your concerns cause you to overtighten the screws. They need to be tight, but not torqued into submission.

I like to set all the knives with all the screws snugged and then go around and check each one just to be sure.

Did you get to watch Vaughn’s video? Very valuable in a lot of ways.

-- "...in his brain, which is as dry as the remainder biscuit after a voyage, he hath strange places cramm'd with observation, the which he vents in mangled forms." --Shakespeare, "As You Like It"

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