tilting head saw vibration while cutting bowl

[ronallo]

I've been happily using a Pegas 21" saw for the past year for 90 degree cuts. Vibration seems very low. Easily passes a nickle test. The blower doesn't visibly shake. No complaints; quite impressed. Enjoying compound cutting ornaments lately.

Last night I tilted the head for an approximately 45 degree angle cut for the first time to try out bowl making and the vibration made it challenging to stay anywhere near my lines. The saw was jumping all over the place and my cuts went way off course. The blower was flapping around. Not fun cutting out that small bowl. I hadn't considered lateral vibration might be an issue when selecting this saw. The ability to keep the table level was a selling point.

Is it expected that a tilting head saw like this will have increased vibrations when tilting the head for angle cuts at the extreme (45 degrees)? I'm trying to gauge what's reasonable as far as reducing vibrations with angled cuts. How much is it the saw, stand, degree of angle, or technique?

I've got the saw mounted to a stand I had around (Harbor Freight Central Machinery universal tool stand) with some 3/4" plywood bolted to the stand and the saw bolted to the plywood. The middle and base also had a 3/4" piece of plywood bolted to the frame to form shelves, but obviously that's not enough to resist the lateral forces.

Maybe this stand is fine for the vertical motion of a 90 degree cut, but I need to stabilize the stand more to lessen lateral vibration? Thoughts on what might be sufficient to decrease lateral vibrations for a stand like this?

Or maybe my best course is to buy or make a new stand that is better designed to lessen vibrations when doing angle cuts?

[OCtoolguy]

I've got 2 Excalibur saws and I've cut up to 32 degrees with no problems. I'm wondering if you might need to adjust the motor to lessen the aggressiveness of the blade angle. It's an easy thing to do and it seems to "tame" these saws considerably. You might give a call to Denny at Artcrafters online or Ray at Seyco for their input. 45 degrees is a pretty steep angle but it should be doable. 

[Bill WIlson]

I've never had that problem with my Excalibur either.  Mine is mounted to the factory stand.  Not sure if that is a significant factor or not.  I would presume if the saw is solidly mounted to a solid frame, it should handle angled cuts as well as vertical cuts.  I don't think there is anything magical about the factory stand.  It's just a 4 legged stand, with splayed legs and the saw is held on by a bolt in each corner.

Is there any possibility that something is hitting the bottom of the table, when it's tilted @ 45 degrees?  Have you tried less severe angles to see if the problem exists at any other angles other than 45?

[OCtoolguy]

Try putting your saw back up to 90 degrees and turn it on. Then slowly tilt the head until it starts knocking or vibrating. You might find something that is interfering with the mechanism. Try it in both directions to see if it is the same.

 

Edited December 14, 2023 by OCtoolguy

[rjweb]

Ray, does your head hurt, that's a good point first 90 and then slowly angle it, that should tell him something, RJ

[kmmcrafts]

A pretty common issue with these type of saws is the threaded rod that connects to the rear knob that adjust the upper arm.. after years of raising and lowering the arm the threads get hammered each time you lower that arm and it comes down kind of hard.. after so many times of this the thread get worn and the vibration of the saw running etc and raising and lowering the arm will eventually get so bad that the knob will start turning on it's own.. This usually results in the upper arm losing its parallel to the table position.. 

I don't know if this is what is causing your issue but it's worth putting the saw back at 90 and checking the distance from the upper arm to the table top at front and back of the saw.. The distance should be the same at both ends of the upper arm.. If not then you need to adjust the knob at the back of the saw until you get it level to the top of the table..

[ronallo]

TL;DR: I think it was mostly a combination of the blade contacting the table (bad!) and the stand not being sturdy enough (cheap!).

Thank you all for the helpful suggestions.

When I took another look today, the first thing I noticed was what is pictured: The throat of the saw had a gash in it in the place where the blade evidently was rubbing when angled. I had to deburr around it a bit for wood to slide on the table without catching. So I think the blade rubbing directly against the table may have been part of the issue increasing vibration. The table was being cut along with the work piece. (Those modified geometry Pegas blades sure can cut.)

While the table can probably be adjusted to the left or right a bit, I still don't see how it is possible to cut at anywhere close to 40 degrees without the blade contacting the table with as narrow as the opening is. While the dust collection is excellent (if super loud!) and there's no potential bump transition from the table to the throat plate, I'm now wishing the table allowed for replaceable zero clearance throat plates which could be swapped out for different angle cuts, similar to making zero clearance plates for the table saw. Maybe there's some adjustment or other misalignment I'm missing, but I can't see that there's enough clearance to cut at sharper angles.

Do other scroll saws with solid tables without a replaceable throat plate have this kind of issue with the blade rubbing against the table? Are there other issues with tables with replaceable throat plates? Wondering how much this will annoy me and if I might try to get a different, compatible table with a throat plate, but that may have its own annoyances. Looks like some of the older Excalibur saws had a wider opening for the blade than the current crop of similar saws. Maybe I just need to resign myself to cutting into the table until there's a nice groove there for the angled cuts I want to do?

It didn't appear as if anything else was rubbing when at an angle, except the "Protection bracket-Down" (part 94 here: https://qtena.com/images/90750 parts diagram A.jpg), which appears to be a bracket similar to the hold down bracket on the top. It sits in a different position against the table when tilted. That might have exaggerated the vibrations some. It seems as if this part isn't necessary for the saw the function, but it does appear challenging to potentially remove it without other disassembly. Seems fine to remove if I can figure out how, right?

I did try running the saw while slowing tilting the main body under the table to the left away from the dust collection port. The vibration did pick up once I got past about 15 degrees and continued to increase through the arc to about 30 degrees where I stopped. I didn't want to mar the throat of the table any more by tilting it further. I cut some scrap at 30 degrees. Even at 30 degrees with a bit of pressure on the blade to the right and the blade appeared as if it would touch the table. The vibration while cutting was not as bad as I experienced the other night, so seemed possible to stay on my line. Still not as vibration free as at 90, but workable.

With this test I did find that the stand the saw is attached to was shaking more as the head was angled more. The stand is mounted to a universal mobile base of which two wheels still contact the ground, and the wheels are in the same direction as the motion of the saw. Being on wheels can't help any, especially in that orientation. The metal of the stand legs vibrated; it just doesn't seem sturdy enough for that lateral motion. I think I need to work out a better stand.

I had the speed up about half way, which has been where it has been most of the time I've had the saw. It has felt comfortable enough for anything I've done before. I lowered the speed some and that helped a bit with the vibration at the expense of speed of cut and potentially, at my skill level, accuracy of cut.

Finally, I checked the upper arm distance to the table and it appears to be so close to perfect that I dare not try to mess with it yet until I try addressing other issues.

In any case, the tiny ash bowl I started which brought me to all of this is coming along nicely. With as rough as the cut was, I sure learned a lot about how to sand inside a bowl.

 

[OCtoolguy]

Regarding your stand, both of my saws are on stands that I built out of 2x4's with a plywood top that tilts. The read legs have 7" wheels. The saws both sit on foam rubber fatigue mat rubber. Zero vibration. After looking at your picture, I see the problem. The pass through hole is far smaller than either of mine. Mine are not worn. They are just larger. I think yours is either made wrong or that's how Pegas is making them. I'd take a die grinder and hog it out. But before doing that check to make sure the table is not mounted upside down. The hole should be beveled on one side.

[BadBob]

Something is wrong. I have A Pegas and an EX-21. Both tables have a bevel on the bottom. The blade does not contact the table when I tilt the head on the Pegas as far as it will go.

Here are a few things that come to mind:

• Something may be bent or misaligned or possibly defective in some other way.
• Is the table position adjustable?
• Could the table be mounted incorrectly?
• If the saw is rigidly mounted, is the plywood flat?
• Is the stand flat and square?
• Could the stand be causing everything to be twisted or warped slightly?
• Are the blade clamps adjusted so the blade is centered in the clamps?
• Run the saw at its slowest speed and observe the blade from the front. Does it move straight up and down or wobble? The clamps should be adjusted so the blade is centered and 90 degrees to the table surface.

[ronallo]

Playing around with the angle adjustment some more and it seems as if the rack and pinion is, I don't know, floppy. At 90 degrees it settles into the center of the opening. As I begin to adjust it to one side it is fine for a bit but then a little over 10 degrees it begins to slip to the side and the blade gets closer to the opening at the top of the table. If I support the back of the head near the motor I can keep it centered for a bit longer, though letting go and tightening the adjustment knob results in the blade being in contact with the table again.

The scale (with and without using the detent) never read zero when the blade was square, but I've learned to ignore those scales on other tools as inaccurate, so didn't try to fix it at the time. I use a known good square to square instead. And the blade is in the center of the opening at 90 degrees. But it may be that I need to get this dialed in by adjusting the trunion to square. When I got the saw I may have done an adjustment to the table position to center the blade. So a combination of these may be enough to cause the rubbing. I'm skeptical that adjusting the trunion and table will fix the issue completely with the slop and flop of the head when tilting, but when I get a chance to pull it out I'll give that adjustment a try. Maybe these adjustments to square things back up again will resolve it at least for ~30 degree cuts.

With the rack and pinion tilting head saws are there other adjustment points I should be looking for? Nothing else, to my untrained eye, stood out as a clear misalignment.

I did look around for images and video of other Pegas saws in use and found this example in the attached picture. So at least I'm not alone in this being an issue.

 

[ronallo]

I see what was happening with regards to violent vibration now. The scale on the Pegas goes further than 40 degrees, but the saw head should not be tilted more than 40 degrees. If it is tilted past that then the chuck head hits the table. Ugh. Hopefully I didn't damage the saw by having gone just past 40 degrees. I checked straightness in every direction I could and I don't think I damaged the saw, but we'll see. It seems to be running true as far as I can see. (I did find I could further fine tune the squareness of the upper arm to the table to by a hair to get the blade running at a true front to back 90 degrees vertically, but haven't done the adjustment yet since I wasn't previously experiencing any issues.)

My feedback to manufacturers of saws of this design would be that if the saw can't tilt more than 40 degrees at least don't show the scale go beyond 40. Even better is to add an adjustable positive stop which prevents tilting further than the capacity of the saw. It doesn't appear as if my Pegas has positive stops. But in the end the vibrations were the result of user error; I didn't check whether something was wrong before proceeding and did not remember what I read in the specs and manual (which I actually did read when I got the saw last year) which state 40 degrees max (dependent on direction of tilt with the dust collection installed).

Now on to alignment of the blade when tilting the head which caused it to rub against the throat. I resolved that by simply adjusting the table with the 4 inset allen bolts on top. That's basically the only adjustment I did on the saw when I first got it in order to have the blade run right in the middle of the opening. This moves the blade closer to the left of the opening at 90 degrees, but now allows for an angled cut at 40 degrees with a good bit of room to clear both the bevel below the table and the narrower top of the table. Maybe still possible for the blade to hit the table if the work piece is forced and deflects the blade, but looks to be fine for a good, slow, steady cut. This also reset the saw so the red cursor is very close to zero when the saw is at 90 degrees. Not entirely sure why. So a bit strange that the blade isn't centered in the opening while the blade is at 90, but that appears to be the case. The trunion adjustment may be what's needed to resolve both of these alignment issues at the same time. I'd also fiddle with the blade clamp centering some but for me having the blade a bit to the left now allows me to tilt the head without the blade hitting the table, so I'll also keep that potential adjustment in mind for the future. It looks centered enough in the chuck, but I didn't do more than just eyeball it.

Finally the slop/flop I was having when tilting the head. A trunion re-alignment may help align the front and rear racks better, but again, not the job I'm going to take on now. What I did find was the linked video which pointed out some bolts rear and front which need to be tightened up near the trunion. The rear tightened with an 11mm wrench; the front behind the knob with a 4mm allen wrench (maybe 5/32" allen wrench). Tightening each of those a bit appears to have removed most of the the slop/flop when the tilting head is being adjusted. Tightening these means that once the saw is set to the correct angle it doesn't as readily move out of adjustment as you're tightening the knob. I hadn't seen anything about this adjustment before, so happy I watched this video through even with the terrible audio at parts.

Now with the blade running at a bit less than 40 degrees with the head tilted to the right, there's no blade rubbing against the table on the right of the opening and the vibration isn't as extreme as I experienced previously (the chuck isn't hitting!). There's still more vibration than I would like, and I think my next step is to try removing the stand from the mobile base. I'm seeing the wheels move just a bit left and right, so until I remove that as a possibility for increased movement, I'm not going to try further stabilizing the stand or replacing the stand. Once I have the stand firmly on the ground, I'll try to remember to update on my experience with vibration with this saw with extreme angle cutting.

Thankfully I got done cutting most of the Christmas gifts I hoped to get done, so going down this rabbit hole hasn't put me too far off schedule. And with a small shop I don't want to be creating a lot of sawdust anyways while I'm applying finish, so taking the time to get things tightened and re-adjusted well enough was fine.

 

[ronallo]

And now I see part of the issue with my misunderstanding regarding tilting capacity. The sites which sell the Pegas 21" saw state it can be tilted to 45 degrees (with the head to the right or if the dust collection port is not installed in both directions), but the manual says it can only be tilted to 40 degrees max in either direction. I wonder how much specs and reality match up for other saws of this design. Or is the manual wrong and people have successfully tilted the Pegas saw to more than 40 degrees without issue of the chuck hitting the head? Still wondering if this might be a misalignment issue for me and how I can test this without potentially damaging the saw.

The Excaliburs appear to state in the manual that it can tilt to 45 degrees. I wonder if that's true in reality? Since part of what I want to experiment with needs 45 degree cuts, I'm wondering if I just picked the wrong saw afterall? Is it possible that it is the blade chucks that are different enough to cause a decrease in cutting angle?

Edited December 16, 2023 by ronallo

[OCtoolguy]

I'll try setting mine at 45 degrees. I have Pegas chucks on both saws. They are considerably smaller than the Excalibur chucks so I don't think they would cause a problem.

[kmmcrafts]

2 hours ago, ronallo said:

And now I see part of the issue with my misunderstanding regarding tilting capacity. The sites which sell the Pegas 21" saw state it can be tilted to 45 degrees (with the head to the right or if the dust collection port is not installed in both directions), but the manual says it can only be tilted to 40 degrees max in either direction. I wonder how much specs and reality match up for other saws of this design. Or is the manual wrong and people have successfully tilted the Pegas saw to more than 40 degrees without issue of the chuck hitting the head? Still wondering if this might be a misalignment issue for me and how I can test this without potentially damaging the saw.

The Excaliburs appear to state in the manual that it can tilt to 45 degrees. I wonder if that's true in reality? Since part of what I want to experiment with needs 45 degree cuts, I'm wondering if I just picked the wrong saw afterall? Is it possible that it is the blade chucks that are different enough to cause a decrease in cutting angle?

I think the manuals are basically copies from the original Excalibur ( before China took them over ) with updated front page and images.. Whoever proof reads the material probably has no clue of the differences, LOL 

[ronallo]

17 minutes ago, kmmcrafts said:

I think the manuals are basically copies from the original Excalibur ( before China took them over ) with updated front page and images.. Whoever proof reads the material probably has no clue of the differences, LOL 

Yes, that's often the case with these tools which are clones that they also clone the manuals. But in the case of these Pegas saws the manuals appear to be correct ("head can be tilted 40° left and 40° right...") and the sites selling the saw appear to list incorrect specs on their site. On some sites it simply says 45 degree blade tilt range, and other sites at least note that the dust port prevents the saw from tilting more than 35 degrees to one side. While the similar Excalibur saws have manuals I've seen which state 45° head tilts--but not having one of those saws I can't confirm that's an accurate operating range.

90.750Manual-2.pdf

[ronallo]

I removed the stand from the mobile base and it helped with the vibrations some on angled cuts. The metal for the stand is so thin that there continued to be some vibration. I tightened down all the bolts attaching the plywood to the stand and the saw to the plywood, and I wedged the middle shelf in tighter. I tried wedging a 2x4 and some shims between the front legs and another 2x4 between that back legs, and this has brought the lateral vibrations way down. I expect the 2x4s are a temporary solution but now I know bracing there will make a difference.

BTW, here's another video which shows an EX saw where the blade hits the table at 45 degrees.

 

[ronallo]

On 12/16/2023 at 5:09 PM, OCtoolguy said:

I'll try setting mine at 45 degrees. I have Pegas chucks on both saws. They are considerably smaller than the Excalibur chucks so I don't think they would cause a problem.

@OCtoolguy I'm wondering if you've given this a try on your Excalibur and what you found. I'm satisfied that I've resolved things enough, but still wondering if other saws do have a greater range for tilting the head.

[OCtoolguy]

I'm sorry to say that I haven't even gotten out to my shop since I said I would check. It's been hectic around here and I have no excuse for not checking. I'll try to get to it tomorrow to satisfy both of our curiosities. My BAD!

[ronallo]

Whenever you can. I know how hectic this time of year can be.

[OCtoolguy]

Ok, here is my report. I zeroed my Wixie angle gauge on the 21 inch saw. It will travel and operate with no problems to about 47 degrees to the right side. But to the left side, it won't go beyond about 35 degrees because the Pegas lower clamp hits the bottom of the table. I have no idea whether it would make it any farther if the original clamp was installed. I did as I suggested and ran the saw on slowest speed and cranked it both ways to see how far it would go. To the right, actually beyond 45 but to the left, it started banging so I looked under the table to see what it was. It was the knob holding the blade in. So, I took the blade out and had the knob turned a bit to the side but it finally did hit when I went far enough. 

As for the 16 inch saw, I have a dust collection system on it that makes it impossible to go beyond about 30 degrees to the right. Not sure about the the left. I figured that I never use that saw for angled work anyway. It has Pegas clamps also so I figured it would have the same problem as the 21 inch saw. 

Now, just for the sake of this subject, I can't imagine if/when I would EVER need to go to 45 degrees. I've never run into a pattern that demanded it. I make bowls and so far 32 degrees was the most I've tilted the head. I'd like to hear why anyone would need anything more.