Step 21 - Installing Saw Blade question

Questions and comments concerning the assembly of the Jointmaker Pro

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Step 21 - Installing Saw Blade question

Postby Doug » Wed Apr 15, 2009 6:44 am

This may be obvious but I dont find it mentioned in the assembly steps and haven't found it mwntioned on any of the forum threads.
Step 21.6 says "Raise blade to aprox 1/2" above table (front and back)"
Do I infer from this that I should first level the blade to the table with the pitch adjuster screw? Previous installation steps and the angle on the blade currently have mine higher at the back than the front.
Doug
 
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Postby User304209 » Wed Apr 15, 2009 7:54 am

Doug,

What Step 21.6 does is set you up for the Blade Alignment in Step 22.
In Step 22 you are going to need the blade raised to that 1/2 inch height front and back above the table in order to align the blade to the tables, by holding a hex key wrench against the locked fence and following the steps as outlined. (and yes the leveling is achieved with the pitch adjuster screw.) Remember it's the blade housing that aligns to the tables not the other way around. Caution // the sacrificial fence at this point is not to be installed until after this step is completed. - And to that end it's probably best to wait until you have the JMP secured to a table first before you make your first cut into the sacrificial fence. After all your alignments are completed the front of the blade will again be lower then the rear. (see below)
Take a look at this video to familiarize yourself with the procedure.
http://www.youtube.com/watch?v=MdE3zGRQevY

hope this helps,
Roger

I reprinted from my review on the JMP below the section on making your cuts after your set up is completed.

Cutting and work holding
As John remarked "When you make a cut and it's a new species of wood, or a new width or a new thickness or whatever, it's a good idea to find out where you're at." This is done with a light cut to gauge the resistance of the cut. In some woods you can't sense a thing...others you know intuitively that you need to make a pitch adjustment. In powering/operating the Jointmaker Pro You're pushing with one hand and cranking with the other. Within this rhythm there are three basic ways to approach your cut; one is to make one turn with the crank per stroke cycle with the sliding table. With this technique it is likely you're not engaging all of the teeth and the cut occurs on the back half of the blade - and this works fine. By rotating the crank more than one rev (depending on the pitch/width/species variables) you will engage more teeth and lighten the chip load per tooth. In order to do that you need to determine, through cutting resistance, the optimal pitch for your board - this takes about 15 seconds once you know what you are doing.
The third way of sawing is by pushing forward a few inches, back up an inch, push forward twice as far as the first time, back up an inch and work your way down the blade while climbing the blade - all without a full table retraction. This works too but relies on touch to determine when to stop each forward motion and is not as uniform as a full pass stroke.
When holding small stock by hand, the closer your fingers are to the blade (sounds crazy, but in practice it's not) the less vibration and more control over the negative feed of the blade. When cutting extremely small length pieces it is advisable to double-stick tape a false table of aircraft plywood (1/16" thick) to the sliding table (the two tables are most often bridged by the fence and act as a single table), make a through cut and your fall-off will stay on top of the table. This technique is also valuable for knowing exactly where the kerf of the saw is and this kerf can be used as a dead-accurate reference - like cutting marked dovetails on the proper side of the line, this is incredibly accurate and easy. And yes, you can cut your finger if you put it in the way of the blade. Keep in mind; this saw is no more dangerous than any sharp handsaw, in my opinion. Although the tables can, and do work independently, I found the cuts to be easier when they were bridged with the fence. And in most of the cuts I wanted to test, the tables were bridged. Miter cuts require a rear bridge for the cuts to be perfect. I found that that you monitor the cutting action by the sounds you hear. When you hear a "rumble" in the blade, the pitch is too aggressive, or there are too many teeth engaged with the stock - wide boards are cut differently than narrow stock. If the falloff portion of the stock is not clamped, you'll hear it. I found that perfect cuts were predictable when the stock was clamped on both sides of the blade. Remember, when sawing by hand your stock is either clamped or held in a vise, with the Jointmaker Pro your vise/clamp is the table and you need to know that accurate work can only be achieved if your stock is rigidly held. It's like any hand saw operation, let the saw do the work - if possible I recommend always clamping your stock with the exception of really small cross-sections. Determining how to pitch the blade and table technique is part of the "getting acquainted period" I continue to mention. If not clamped tight enough, the work will slip and you could damage your blade. If you don't want a small burr on the falloff piece, it's wise to clamp both sides. Having 180 grit sandpaper on the face of the fence (with double faced tape) really helps the holding power and combats slippage; just make sure not to place it where you would trash your saw sharpness.
In summary, when the pitch is correct, the stock firmly clamped, this tool sings. And it is easy to tell, it simply sounds efficient.
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Postby Michael » Wed Apr 15, 2009 8:22 am

Hi Doug,
Roger is correct. You need to raise the blade above the tables in order to calibrate the blade while not hitting the teeth as in Step 22. The 1/2" was just an easy number. It does not matter what the pitch of the blade is.

Michael
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Postby Doug » Wed Apr 15, 2009 9:05 am

Thanks guys. One other question on the blade height. Should the blade completely be beneath (or at least flush) with the tables when lowered all the way. I noticed after posting that I have just a skosh of the blade projecting when all the way down. I think I've figured out that in my concentration on getting the DT way rails co-planer I managed to get them not 100% flush with the top of the front /rear plates. If it's normal for the blade to project up a hair, I'll wont go back and readjust those but I think that migh be enough.
t
Doug
 
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Postby John » Wed Apr 15, 2009 10:16 am

Doug;

It is desirable, for several reasons, to be able to completely lower the blade below table height. Here's why;

1. Blade longevity. If your blade does not retreat below table height, I guarantee that at some point the tables will attract squatter tools or material that will damage the blade.

2. There are some cuts, like cutting the cheeks off of a tenon where your cutting depth may be as small as 1/16". If you can't lower the blade at the back enough, you will only be able to use the last few inches of the blade to make this critical cut--not desirable.

So there you have it. The fix is as follows;

1. Using the pitch adjuster, lower the rear of the blade as far as it will go.

2. Raise the blade so the front is 1" high off the table.

3. Measure the height of the blade at the rear and subtract 1" in your head. This fractional distance is your guide to the adjustment you will need to make.

4. Remove the blade.

5. On page 7 of the manual (Step 6) you will need to reset the thread length of the Height Screw Assembly. This new distance will be 7/8" plus the fractional distance from your measurement above.

For example, using the steps above, if the front of your blade is at 1" and the rear is at 1-1/16". You would need to lower the Height Screw Assembly a minimum, of 1/16". It is not possible to adjust exactly with the gear train assembled but it doesn't matter...

The threaded stud of the Height Screw Adjuster is 18TPI. 1/18 =.055 per rev. 1/16 = .0625", so you would need to make a two revolution downward adjustment for a total adj. of .110".

This will enable you to lower the rear slightly more than the front which is A-OK.

Hope this helps.

--John
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Postby User304209 » Wed Apr 15, 2009 10:20 am

.


Doug,

A skosh, wow. I didn't know that term until I met John up in Portland. You two must come from the same village. :wink:

Regarding your "skosh" of a protrusion of the blade above the tables, no I don't believe it's normal. Personally I would take the time to make it right. Keep in mind that you are in time going to be laying out your dimensions with a pencil on your tables and that skosh is going to get in the way unless you intend to keep a steady supply of band-aids hooked to your JMP. And more to the function of the JMP when you go to lay down your aircraft ply to make a zero tolerance throat plate (that will first be doublefaced taped to the tables) you are going to get a bit stuck when pushing the tables / starting to bring the blade up.
I'm sure Michael will bring up another couple of reasons.

cheers,
Roger

added......
hmm, ok I'm a slow typer (and had a phone call in between).......I see John beat me to the punch.
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Postby Doug » Wed Apr 15, 2009 10:46 am

User304209 wrote:.


Doug,

A skosh, wow. I didn't know that term until I met John up in Portland. You two must come from the same village. :wink:
....


Must be an orYgun thing. :lol: I lived in Eugene many moons ago.

Think I'm going to loosen the threads on the ends of the DT ways and tap the whole rail assembly up a skosh until the ends are perfectly fglush with the plate top edges and see where that gets me. They aint off my much but might just raise the tables another 1/128" or so. If that doesn't eliminate it, I'll dive in to John's adjustment method.

Thanks
Doug
 
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Postby John » Wed Apr 15, 2009 11:15 am

Doug;

Strongly urge you to not take the shortcut mentioned above. The ways really need to rest on pocket shoulders--they bear all the weight of the tables and stock. The correct fix should cost you less than an hour.

If you follow my suggestion, you will never have to deal with this issue again--plus, you don't want to get an "I told you so" from the inventor!

:)

--John
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Postby Doug » Wed Apr 15, 2009 12:25 pm

Gotcha. I wasn't viewing it as a shortcut but thought maybe I'd goofed by not ensuring the plate and DT way top edges weren't flush when I installed them. They're currently sitting at the bottom of the shoulder pockets and will stay that way.

Thanks
Doug
 
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Postby Doug » Wed Apr 15, 2009 1:53 pm

John
After lowering the pitch adjiustment screw all the way and the front crank, it's not the back of the blade that's too high. It's the front. The steps you outlined earlier I think are to address the blade being too high at the back. If I pull the front edge of the tables even with the front edge of the blade, it's aprox the front 4-1/4" that is riding too high. Starts with the teeth just barely even with the tables and rising up to maybe 1/32" at the front of the blade. I did steps 5 & 6 with exactly 3/4" and 7/8" plus a hair respectively for the amount of thread protruding. Does this mean I need to disassemble the keel and run the font one down a bit further than 3/4"
??
Doug
 
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Postby Michael » Wed Apr 15, 2009 4:12 pm

Hi Doug,
It indeed sounds like the front of the blade will not go beneath the table top plane. The easiest way to lower only the front is too remove the four screws that attach the long black rear shaft to the keel. All screws are accessible and should be easy to remove. You will then be able to crank the front of the blade a bit lower. Then reattach the shaft to the keel.

Let me know if this works for you.
Thanks!
Michael
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Postby Doug » Wed Apr 15, 2009 6:11 pm

Michael
That took care of it and was a whole lot simpler than what I thought I'd have to do to run the threaded part further in.

Thanks

On to Step 22 tomorrow.
Doug
 
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