Carvex Blade Guide Tensioning/Position?

[darita]

I watched a vid of Paul Marcel tensioning the blade guides.  My blade seems to sit really far forward compared to his.  The photo shows the blade sitting as far back as I can push it.  Seems most of the blade sits outside or forward of the blocks, in the "V" part of the guides.  Is this the normal position?  I only get a mm or two of the blocks to contact the blade.

 

[ear3]

That's the way mine sits as well -- even when you try to force it back, it slides forward as you tighten it up.  I remember thinking the same thing -- why didn't it sit all the way back like in the video.  But I just took this as the normal operation, and have had no problems with the jigsaw's operation with this configuration.

 

[darita]

Well, something's not right here.  Seems the blade should run between the "guides" and if it's not, why are called "guides"?  I'm sure there's a reason that Paul's Carvex blade sits farther back and in the guides, than ours does.  Someone here is going to have the answer...they always do.

 

[Wuffles]

Does the pendulum setting make a difference?

 

[Rick Christopherson]

It's due to the orbital stroke and that your picture is taken with the blade in the parked position. The bearing will be pushing the blade forward in the parked position.

 

[darita]

When the setting is at no swing, the orbital bearing is furthest forward, so yes, the blade is held out in the V of the guides.  With the setting at full swing, there's a little play to push the blade back and that's where you see it in the pic...not much "guiding" the blade.  Really, the blade back just sits at the back of the V.
If you look at Marcel's blade back, it sits in the very back of the carbide guide...there's lots of guide to actually guide the blade.  Looks like 3/4 of the blade is in the guide.

 

[Rick Christopherson]

Darita, when you turn off the saw, it will always stop in the parked position, with the blade fully retracted. It does this to facilitate blade changing. The electronic motor controller knows the rotation of the motor so it will stop the motor when the bade is retracted. The only way to get the saw to stop outside of the parked position is to unplug the saw while the motor is running, and let the motor coast to a stop at some random position.

Note in the image below that the oval representing the pendulum stroke is not a vertical oval, where the apogees do not fall on maximum up or maximum down strokes. This is why you see a slight difference in the parked position depending on the pendulum setting. Nevertheless, in either case, the rear guide bearing is close to its maximum forward position when the blade is in the parked position.

This is why it appears to you that the blade is not moving back between the guides when viewed with the saw turned off.

[attachimg=1]

 

[darita]

Rick, when pendulum setting is set to 0, my rear bearing is up against the blade and the blade can't be pushed back at all.  At this setting, why is the blade not resting well within the flat part of the guides?  Far as I can tell, when the blade is running, the back of the blade is sitting in the point of the V.  I would think the blade would be well in the guides, like with a band saw, no?  Also, why is Paul able to push his blade so far back in the guides, while I can barely get a mm into the flat of the guides?
At precisely 12:40 on Paul's vid, you can see where his blade sits.  How is that? Look in the tight shot...

 

[Rick Christopherson]

All you need to do to realize how far into the guides the blade is really traveling is overtighten your guides just once!  [big grin] [big grin] [poke] [poke]

Because these guides were a new feature of the 420 saws, many dealer and reviewer videos over-emphasized them, and especially their adjustment. This lead to a lot of people constantly adjusting their guides to be too tight, and for every cut. So I specifically tried to temper this emphasis in the Supplemental Manual. It isn't necessary to readjust your guides for every blade change, or even for every type of cut.

Because of the V-notch, the guides are still functioning even in a non-pendulum stroke. They also don't need to be super close unless you are making a deep cut with a long blade. The standard guidance is plenty sufficient for most common shallow cuts. The guides play their most important role in a deep cut with a full pendulum stroke.

 

[Rick Christopherson]

At precisely 12:40 on Paul's vid, you can see where his blade sits.  How is that? Look in the tight shot...

You added this video after I started writing my last posting. So I'll cover this separately.

You can clearly see in his side by side shot that his blade is NOT in the parked position. It is fully extended. Paul-Marcel did what I mentioned above, and unplugged his saw while running to get it to stop outside of the parked position for photographic purposes.

 

[darita]

Rick, thanks so much for clarifying this stuff. So these guides do not operate like bandsaw guides in that the blade does not normally operate within the flats of the guides, when there is no pendulum action taking place...is that right?

 

[Rick Christopherson]

Put it this way; I have never readjusted my guides...for 2 reasons:

1) I originally adjusted them using the thickest blade possible. This way I don't have to worry that they will burn a thicker blade.

2) Most importantly, I still have never needed to make a deep cut beyond typical 4/4 (0.75 to 1.0") stock.

If I was cutting through deep stock where perpendicularity of the cut was critical, then I would take the time to readjust my guides for that particular blade thickness. Beyond that, the blade still won't deflect much from perpendicular through most 4/4 stock. The upper blade holder is enough to hold the blade perpendicular all on its own. Granted, if I was using a really shallow scrolling blade on tight curves, then I would probably adjust the guides for the blade.

Oh, yes, you are correct about the bandsaw analogy. These blades are stiffer than a bandsaw. So the guidance system will work just fine if it only controls the rear of the blade. The blades don't twist like a bandsaw will.

 

[darita]

Rick, thanks again for the help.  Going by what you said, I was able to tug on the blade and it popped right out to it's lowest position.  I then put the orbital adjuster in the maximum position and I was able to push the blade back into the same position that Paul's blade was in.  I was then able to make the proper adjustment to the guides.
Sure wish Paul would have explained that in the vid, but I guess he couldn't include everything.  I'm still not quite sure why in full pendulum action, the guides function fully, but in non pendulum action, the guides are much less a factor?  You're right that one rarely cuts thick stock with a jig saw, but still, that's one of the functions that makes the Carvex desirable.

 

[darita]

Here's a pic of my blade in a better position in the guides, to make the adjustment.  I still don't understand why, if the blade doesn't ride between the guides during "0" setting and only guides the blade when the blade pendulums back, away from the work, then how do the guides provide any real function, like that on a bandsaw? Seems like the guides should operate in the position pictured, all the time or at least on the upstroke.

 

[Rick Christopherson]

I think you may be having problems with this because you are trying to compare it to a bandsaw when it is not the same as a bandsaw. For starters, a bandsaw blade has to be flexible, but a jigsaw blade shouldn't be. Because the blade is much more rigid, the saw will still cut quite nicely even if the guide wasn't there at all. Many jigsaws don't have lower guides.

Additionally, because the blade is stiff, even a simple v-guide will still properly guide the blade. The main purpose of the guide is to control the side-to-side deflection of the blade, and that can be accomplished by simply controlling the back of the blade. A bandsaw blade needs greater control against twisting than a jigsaw blade. This is why bandsaw guides control more of the sides of the blade than jigsaw guides. By itself, the upper blade holder provides significant control over twisting that a bandsaw doesn't have without its guides.

It's not so much as the guides aren't controlling the blade without pendulum swing, as it is that the guides need to accommodate the deeper swing when the pendulum motion is active.