Tensioning question

[TAIrving]

Is this normal?  Is there an adjustment to take this out?

I am a top feeder.  When I clamp the blade in the bottom clamp I sometimes rest my thumb a bit heavy on the clamp.  The picture shows what I get if I then set the tension with the white tension lever and immediately release it.

I think there must be a little slack in the bottom clamp.  It is not due to the blade slipping in the clamp.  This does not happen if I put upwards pressure on the bottom clamp while clamping the blade.  

The scroll saw is Pegas, not quite 2 years old.  I am not sure how long it has been doing this.  This blade is Pegas MGT1 but it does it with all blades but it is more noticeable with smaller blades.  

The pattern is Steve Good's Shadowbox Butterfly from last Friday.  

Thanks in advance.  

[Bill WIlson]

I'm a bottom feeder, using an EX-21.  I usually press down a little on the top arm to take up any slack that may exist between the arms, at rest.  This was necessary on my old DeWalt.  Not as much on the EX, as the tensioning mechanism is different, but old habits.....

If the problem doesn't occur when you push up on the bottom clamp, then I suspect it is due to a little slack or play in the distance between the arms, when not under tension.  Try another approach.  Attach the blade in the bottom clamp without using any pressure, up or down.  Tension the blade and release.  Does the blade look like it did in the picture?  If so, unclamp the top and press down on the top arm and reclamp and tension.  Release the tension to see what happens.  I've never used a Pegas, but its design is very similar to the EX and the DeWalt, and there is a little play between the arms, at least on the DeWalt.  I don't necessarily think there is any defect in the saw.  It's just a condition of the tensioning/clamping design.

[kmmcrafts]

It's normal for these type of saws that have 20 bearings and like just as many pivoting points unfortunately. Each pivot point / bearing has to have a bit of tolerance and thus this is what you get.. more noticeable after they have been used a fair amount.. 

I'm not sure how to handle the problem being a top feeder.. If you watch closely as you apply the tension lever you'll see the upper arm pull downwards too.. ( another pivot point to get slop ). When bottom feeding I tend to pull the upper arm down and then use my index finger to push down onto the upper blade chuck while using the other hand to pull upwards on the blade as I tighten the thumb screw.. even doing this sometimes it still gets some slack.. most times I double tension it (ie clamp it lightly without fully locking the tension lever down I immediately release tension and then loosen thumb screw and re-tighten then tension again.. Kinda a pain to use.. I've had several saws over the years and while these style saws cut nicely I've always had issues with this slack.. On a Hawk Hegner style saw there is only two pivot bearings and you realy don't get this kind of issue.   

Take one hand and hold the top blade chuck from moving and use the other hand to wiggle the lower blade chuck.. you'll likely feel quite a lot of slack.. I've found if your bearings are packed really well with grease that this takes up a bit of that slack.. but it don't stay that way for all that long.. maybe 50 hours of run time and you start going back to where you was before adding grease, LOL Be nice if they had grease fittings so you could take a grease gun and pump a little in every once in a while.. 

[OCtoolguy]

Nothing to worry about. Happens to me too. I'm a bottom feeder so once I have the blade up through the hole and positioned in the upper clamp I pull down on the top clamp just enough to take the slop out of the mechanism and tighten the clamp screw. 

[TAIrving]

OK, thanks guys.  I will stop stressing about it.

Kevin @kmmcrafts, 20 bearings?  I did not know that about them.

BTW, I also, do the double tensioning trick you mentioned, it seems to pull any excess slack out of the system.

[John B]

4 hours ago, OCtoolguy said:

Nothing to worry about. Happens to me too. I'm a bottom feeder so once I have the blade up through the hole and positioned in the upper clamp I pull down on the top clamp just enough to take the slop out of the mechanism and tighten the clamp screw. 

I do almost the same., I have worked out a technique where I place the blade with my thumb and middle finger, while applying slight downward pressure on the clamp with my pointer. It has become habit now.

[kmmcrafts]

2 hours ago, TAIrving said:

OK, thanks guys.  I will stop stressing about it.

Kevin @kmmcrafts, 20 bearings?  I did not know that about them.

BTW, I also, do the double tensioning trick you mentioned, it seems to pull any excess slack out of the system.

I may have mis-counted as it was just a guess off the top of my head without really thinking how many are actually in it.. Looking at the parts diagram I count 16 unless I'm missing some somewhere else.. to be fair though three pivot points use 2 bearings each so that doesn't mean there is 16 pivot points.. either way that's still a lot of bearings compared to a Hawk or Hegner style saw.. 

[TAIrving]

10 hours ago, kmmcrafts said:

I may have mis-counted as it was just a guess off the top of my head without really thinking how many are actually in it.. Looking at the parts diagram I count 16 unless I'm missing some somewhere else.. to be fair though three pivot points use 2 bearings each so that doesn't mean there is 16 pivot points.. either way that's still a lot of bearings compared to a Hawk or Hegner style saw.. 

That is a lot of bearings and explains where the slack comes from.