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Greg

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Reply with quote  #1 
I hope someone can help me

 I have a problem with cutting perpendicular 
the thicker the wood the more pronounced it is.  It doesn't happen all the time  but it happens often enough to make cutting puzzles frustrating 
The last cut I tried was a wood animal puzzle 3 of the pieces will not slide through in both directions    If I use a bigger blade its not as bad but then the pieces are sloppy
I don't believe its the saw (Excalibur 30) or the blades (Pegas)  
I have tried different blade sizes  cutting slower  slowing machine speed ( I run at top speed most of the time )
Any comments or tips are appreciated
Thanks
phantom scroller

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Reply with quote  #2 
I have a digital reader for getting the blade at 90 deg to table but you can get a piece of wood cut it so far in to see the cut and then line it up at the back of the blade and it should go straight in otherwise just line it up so it does job sorted.

Slow it down and don't force it.


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AES

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Reply with quote  #3 
IMO, you have a pretty good machine in the Excali, and again, my opinion, Pegas blades are very good too.

I'm sure you know that the head on your Excali tilts (rather than tilting the table), and although there is a zero degree stop (for vertical) on the machine, I give a +1 for the tip above.

That's because it MAYBE possible that your zero stop has moved, and the tip above is simple and quick to do. Just FYI, I do that every time I tilt my head and then return to zero - I don't rely on just the zero stop on the machine.

The only other thing that springs to mind is blade tension. It should go "pinggggg" when tension is correct, NOT "ponng", a much lower note. (Apparently the correct note is middle C if you know what that is. I don't, but it should be a "sharp", quite high-register note, note a duller/lower note, as I've tried to indicate above).

The only other thing (assuming your blade is sharp) is, as already said by the poster above, don't push, just let the machine do the work. Correctly set up, your machine should, with the right blade, easily cut any wood of at least one inch + thick, absolutely square. Mine does.

HTH, good luck.

AES 

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Rosiejane

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Reply with quote  #4 
I feel your pain! I'm having exactly the same problems at the moment. Frustrating to say the least. I'm cutting 30mm (just under 1.25") and now have a stack of broken blades. I always check that the blade is 90 deg to table but I haven't quite hit that balance of speed, feed rate and no sideways pressure. Around the corners is surprisingly not too bad using a bit of a push/pull method but coming out of the corners it's worse. Probably not letting the blade catch up as much as I think I am.
Been trying a few different blades as well. I too want the close fit for puzzles etc. so don't want to go to high blade#. Just to make things even more confusing, sometimes I find that when it feels like I'm using sideways pressure I'm not and when I think I'm not pushing to the side it turns out that I am. I'm using Olson blades but just ordered some Pegas and FD blades from the US.

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BadBob

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Reply with quote  #5 
You can tension your saw blade with an electronic guitar tuner.  The first time I read about middle C. I took my tuner to the garage and tried it.  My blades were very close to middle C.
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Rod T

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Reply with quote  #6 
A very frustrating problem. I still get the same thing when cutting 1" thick and above.
Softwoods seem to be best. Pine, Douglas fir etc.
On my excallibur, I run at about half speed and I also turn the tension knob between 1/8 and 1/4 of a turn tighter. I do this after I have installed the blade. I also wind it back the same amount when removing the blade, so that it is always in the same position. On thick pieces I am generally using 10tpi blades.
Even though I use a very slow feed rate and try to ensure no left or right pressure, I can still get what I call " bent blade syndrome".
The tighter the curved cut the worse it gets.
I suspect this is what is happenning to Greg.

One thing that I have found is blades stretch, which affects the tension. When I install a new blade, I run the saw and push a bit of scrap against the side of the blade to bend it a bit. This stretches the blade. I then loosen the top holder, re-attach and then wind the tension up again. Hope that makes sense. Very quick to do on the excalibur and also easy to see how much the blade stretches. This pre-stretching only needs to be done once, seems to make a difference when cutting curves in thicker wood.
I might do a video on the weekend to show how I do this. It's a bit hard to explain.

I still get the same problem happening, but each of these things seems to improve it a bit.

Cheers
Rod T
BadBob

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Reply with quote  #7 
I'm going to try to help. 

First for the Excalibur. If you set it up according to the manual it does not require a tension adjustment after installing a blade. If you need to do this something is broken, worn, or misaligned. 

While I am sure that blades stretch a tiny bit  I have never had to retension a blade. How did you determine that the blade was stretching?  I'm thinking you would need a precise measurement before and after to know this is what is happening.

You say you are not pushing. Did you test this or are you guessing? To test for pushing put strips of blue tape on the table on both sides of the blade so there is zero clearance. Cut your test piece. if you are pushing the hole in the tape will be enlarged in the direction you are pushing. 

When cutting puzzles the blade needs to be dead square. Close might work on thin pieces but as the material gets thicker the error gets worse. 

I cut a lot of thick MDF and wood on my scroll saws. Up to two inches thick and commonly 1-1/2 inches with #5 or #7 skip tooth blades. You have to cut slowly and concentrate on letting the blade do the cutting. Try to only apply enough pressure to keep the blade engaged.

Using a scroll saw takes some practice. A lot of practice if you want to get good at it. You have to develop a feel for what is happening as the wood is being cut. When I first started I made hundreds of small animal cutouts. May of these when directly in the trash but I slowly got the hang of it.

Here is a dragon I cut from a piece of 2x yellow pine. Yellow pine is hard to cut due to its grain being very soft and very hard. Plus there are lots of resins to gum up things.

20171008-130655 Wooden Toy Puzzle - Dragon - Yellow Pine - Unfinished - 7.5x6x15 Inches.jpg 

20171008-130655 Wooden Toy Puzzle - Dragon - Yellow Pine - Unfinished - 7.5x6x15 Inches




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AES

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Reply with quote  #8 
+1 for all that Bad Bob has written above.(Nice Dragon BTW Bob).

You should NOT need to vary the blade tension once you have set up according to the Excali Manual. 1 extra thought (this is JUST a guess) - at the end of a session do you relax the tension on the blade (i.e. lift up and backwards on the white plastic toggle lever right at the front top of the machine)? If you have a lot of down time between sessions, it MAY be that the blade is stretching a TINY amount if you leave it tensioned at all times.

Apart from that, and all the suggestions above, I can only say, in the nicest possible way, that the likelihood is that the fault lies not with the machine or with the blade, it lies with you!

I do NOT mean that unkindly, but just as BB says, to get good at scrolling, most especially for tight-fitting curvy parts in thick wood, needs a LOT of practising. Just as my good lady always says to me "no one fell down out of heaven on day one knowing just how to do that"ยจ!

There are several excellent sites including Mike Goode with lots of instructions and tutorials on getting good at scrolling, and with respect, I have the feeling you need to do some more intensive practising BEFORE you start on a finished job like a jig saw with thick wood. Have a Google for Scroll Saw practice Patterns.

HTH, and good luck - NO disrespect intended.


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Rod T

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Reply with quote  #9 
Maybe the blade isn't stretching, maybe it is slipping a bit in the holders. 
I'll investigate further. 
When I do my little routine of "Pre-Stretching" it seems to work. 
When I install a new blade and before flipping the white tension lever at the top, the blade is straight.
I then flip the lever to tension, do my routine and then flip the lever back to un-tension. The blade is nearly always a bit bent (left to right) or looser, for the want of a descriptive word.
I then undo the top holder, straighten, re-screw the holder and re-tension the blade. 
If I do the routine again, there is no stretch. 
I do all of this without touching the knob at the back.
I am just assuming it is stretch, but perhaps the blade is just bedding in to the holders. Do know.

Only applies with new blades and some are better than others.
A bad habit of mine is to walk away from the machine when finished and not undo the tension lever. 
Although a good idea to release the tension in down time, it doesn't seem to affect the blade "Stretch".

I only adjust the knob at the back when cutting thick timber, maybe it is a cheats way of trying to cut faster. I agree, this knob should't need adjusting if the machine is set up correctly. 
I might be trying to push the machine beyond what I should be.

I have a guitar tuner, so am also going to try BadBob's idea with this. See what the default "Ping" is on my machine.

Feed rate still seems to be the most important thing.
I'll also experiment with the speed knob also. I generally just leave this set at about half way as that is where I am comfortable (Habit) cutting. Maybe I have it set too low.

I agree with AES, practise practise practise. I am always assuming these issues are to do with my skills (or lack there of), but will go back to the manual and do another full setup etc. of the machine as well.

Cheers
Rod T




Rod T

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Reply with quote  #10 
I was just watching the movie that Phantom Scroller posted about squaring up the blade to the table.

The same guy shows in another video what I was talking about with blade stretching.



This is what I do with new blades, but also give the blade a little extra pressure sideways with a scrap bit of wood when it is running.

Cheers
Rod T
Bucko

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Reply with quote  #11 
Thanks Rod, this video actually has me anxious to install a new blade.
Greg

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Reply with quote  #12 
Thanks to all for the ideas, videos and  support.  I was pretty much sure it is not the machine although I will watch my blade tension more closely and  will do more practice and experimenting with other suggestions and am sure I will improve  thanks again
BadBob

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Reply with quote  #13 
I have three scroll saws. All of them have different blade mounting systems. My Excalibur does this sometimes.  The same as in the video. The other two do not.

I always assumed that it was something to do with the blade seating in the clamps in the Excalibur. Since it doesn't always happen I have thought that I was just not getting the blade inserted correctly. Perhaps they do stretch but with out measuring the length of the blade before and after you are making an assumption.

I did a quick Google search on the subject of blade stretching. I found only a few mentions of it but nothing definitive and no measurements. I found a mention in one of Patrick Speilmans books where he said the blades do not stretch.

Not that any of this really makes any difference. I just find it interesting but not enough to get out the calipers and start taking measurements.


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Rod T

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Reply with quote  #14 
You might be right Bob, as my old Makita scroll saw didn't do this either. 
Maybe it is something to do with the blade seating in the clamps.

and come to think of it, I think I only adjust the knob at the back of the machine if I haven't done this routine first. I could be just adjusting that knob to take up that bit of slack.

I'm going to investigate a bit further over the weekend.

Cheers
Rod T

Rosiejane

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Reply with quote  #15 
*sigh...I think I have scroll saw envy. I'm using a saw with the hanging type blade adaptors...sooo annoying to change the blades, especially when there are a lot of inside cuts to be done.
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