Pegas Clamp Vibration Testing

[hotshot]

Results of Pegas Clamp Testing:

Decided on using an IOS app called Seismometer on the Iphone. (http://yellowagents.com/seismometer) This app records the numerical data so we can get a qualitative measurement


The phone was placed exactly at the same place on the table for each long duration test.  Since the saw takes a few seconds to reach speed and stabilize, there are some variations in data at those speed changes, so to counter I started the saw and let is stableze before I started gathering data, then if the data was skewed for the first few seconds or the last few.

There is some technical nastiness I had to juggle to get the results, but in short, I wrote some code to translate the raw data to a systematic measure of peak to peak amplitude.  Basically, higher amplitude, the more vibration.  Long duration testing ran for about a minute so that any variances would Balance out.  Speed changes tend to upset the balance for a few seconds, so I eliminated skewed data where the speed changed.

My EX doesn’t have speed reference marks, but the numbers on a clock line up pretty good, so I cut out a clock face, cut out the center, taped it over my dial with 1 being the lowest speed, and top speed just happens to land exactly on 11.  Vibration starts kicking in 6, but stays about the same until 8, then starts getting more dramatic after that, so I decided to use 7, 9, 10, and 11 as my speeds to use for comparison points.

There is one particularly important thing to understand about changing the weight of these components, when you add or subtract weight, you may move the point of harmonic resonance.  When I tested the heavier Hegner knob on the original clamps, I saw increased vibration, except at one point, where resonance had made vibration with the lighter clamp higher. 

In the results chart below, just know, the higher the number, the more vibration.

Speed	All Original	Original with Hegner Knob	All Pegas	Pegas with Hegner Knob
7	15.0	14.4	12.1	10.7
9	35.1	34.3	20.2	20.5
10	29.0	31.8	28.1	45.6
11	39.8	37.7	35.1	42.2

Edited February 7, 2018 by hotshot

[kmmcrafts]

So if I read this correctly.. the Pegas clamp does in fact reduce vibration? .. doesn't look like a huge difference to rush out and buy a new Pegas clamp to replace a good ( new one ) on my new saw.. BUT... the reduced vibration could mean longer saw life etc etc.. 

I really want to start using my new EX.. but.. I want to hook up a hour meter to a my foot switch first.. I don't know why.. just mainly because I'm always curious about how many hours are on my old DeWalt.. I really want to hook a meter to all my saws to be honest.. Just to collect some data..  not only for the saw but for projects I make too.. 

[Scrappile]

Interesting.

[Terry Jay]

Steve Good also did a review of the Pegas clamps.

https://scrollsawworkshop.blogspot.ca/2018/01/ichthys-scroll-saw-pattern.html

Appreciate your work and effort on this project.  Thanks.

[tonylumps]

When you were taking vibration tests. What if anything were you cutting.i think that the test should be taken on what you mostly cut testing both Stock and Pegas clamps .The vibration results on the saw just running is so minimal it will be nill when cutting stock.i really can  not see it lasting longer than the stock clamps.i have never had a problem with the stock holders stripping or spreading.If that was a concern than i would go down to a machine shop with a chunk of titanium and have it machined It would be lighter than aluminum and stronger than high speed steel.The problem people are having with the stock clamps are that they are mounting these big knobs on the thumb screw.Very little pressure is needed to hold the blade if you maintain the the tips of the thumb screw.

[kmmcrafts]

3 hours ago, tonylumps said:

The problem people are having with the stock clamps are that they are mounting these big knobs on the thumb screw.Very little pressure is needed to hold the blade if you maintain the the tips of the thumb screw.

Yes, exactly.. My DeWalt is 10 years old.. and I've done a LOT of cutting on that saw.. has the original clamps in it.. . about a year of so after I got it I read about how it's a good idea to have extra clamps.. and guess what.. I bought a couple extras.. and still haven't needed them, LOL..  

[hotshot]

19 hours ago, tonylumps said:

......i have never had a problem with the stock holders stripping or spreading.If that was a concern than i would go down to a machine shop with a chunk of titanium and have it machined ....

I am one of those that did put a big knob on my top clamp.  But I top feed, so the bottom clamp with the stock clamp knob is the one that gets the most use, got loose and eventually stripped.  It is great that the stock clamps work for your style (and they lasted me a good while), but I prefer a clamp that can handle the tension that feels right to me, without having to overthink it.  I like the idea of the Titanium clamps, but somehow I don't think paying a machinist to make these from scratch is going to be within my $$$$ threshold . . . but I love that idea.  Of course, if the Pegas last as long as the original clamp, I won't need it for several years.

That said, I don't see anything in the Pegas design that would reduce stripping anyway.

Yep, don't see a good way to test accurately between multiple saws while cutting as cutting depends on a lot of variables, I'll leave that to someone smarter than me.  In normal cutting, I don't see a reduction in vibration with thin stock, and see an very noticeable increase in vibration with very thick stock.  But I do believe that the stress of cutting resistance is probably much more brutal than the stress of the additional weight.

I do know that the saw with the Pegas clamps "seems" quieter and my perception at my normal cutting speed is that the saw is noticeably smoother, so it is a meaningful reduction in vibration for me, or at least that is my perception.  Regardless if this is or is not a "good upgrade", and I'm a little mixed on it at the moment, I am very excited to see attempted innovation, successful or not.

I first noticed vibration increased when doing thick boxes on the Hegner, but later noticed it increased on all my saws.  I  did a quick monitoring of the EX under load to show this.  I think this is why the DWs that have owners that cut thicker stock seem to give up the ghost earlier, and I'm assuming that would be true with an Ex also.

Edited February 9, 2018 by hotshot

[tonylumps]

5 hours ago, hotshot said:

I am one of those that did put a big knob on my top clamp.  But I top feed, so the bottom clamp with the stock clamp knob is the one that gets the most use, got loose and eventually stripped.  It is great that the stock clamps work for your style (and they lasted me a good while), but I prefer a clamp that can handle the tension that feels right to me, without having to overthink it.  I like the idea of the Titanium clamps, but somehow I don't think paying a machinist to make these from scratch is going to be within my $$$$ threshold . . . but I love that idea.  Of course, if the Pegas last as long as the original clamp, I won't need it for several years.

That said, I don't see anything in the Pegas design that would reduce stripping anyway.

Yep, don't see a good way to test accurately between multiple saws while cutting as cutting depends on a lot of variables, I'll leave that to someone smarter than me.  In normal cutting, I don't see a reduction in vibration with thin stock, and see an very noticeable increase in vibration with very thick stock.  But I do believe that the stress of cutting resistance is probably much more brutal than the stress of the additional weight.

I do know that the saw with the Pegas clamps "seems" quieter and my perception at my normal cutting speed is that the saw is noticeably smoother, so it is a meaningful reduction in vibration for me, or at least that is my perception.  Regardless if this is or is not a "good upgrade", and I'm a little mixed on it at the moment, I am very excited to see attempted innovation, successful or not.

I first noticed vibration increased when doing thick boxes on the Hegner, but later noticed it increased on all my saws.  I  did a quick monitoring of the EX under load to show this.  I think this is why the DWs that have owners that cut thicker stock seem to give up the ghost earlier, and I'm assuming that would be true with an Ex also.

I know with your type of cutting Reducing vibration of any kind is a must no matter how you go about it . But for most scrolling eliminating vibration on any saw starts from the ground up.The things to look for are mostly over looked Somebody goes and buys a 1000.00 saw opens the box on a new saw ,Throws it on a bench turns it on to see how much it vibrates And the first thing you here This saw is a piece of junk My 150.00 saw runs better.Mountig the saw is the biggest mistake a lot of people make

[hotshot]

50 minutes ago, tonylumps said:

....Throws it on a bench turns it on to see how much it vibrates And the first thing you here This saw is a piece of junk My 150.00 saw runs better.Mountig the saw is the biggest mistake a lot of people make....

Yes, I had some vibration in one of my Hegners, tightened the bolts that connected it to the stand, and bam, it was like a miracle.  Running on Concrete was the second thing that really brought that saw under control.  In the portable barn with flexible floor, it would resonate and dance.

------Randy

[tgiro]

24 minutes ago, hotshot said:

Yes, I had some vibration in one of my Hegners, tightened the bolts that connected it to the stand, and bam, it was like a miracle.  Running on Concrete was the second thing that really brought that saw under control.  In the portable barn with flexible floor, it would resonate and dance.

------Randy

And you need to check those nuts and bolts periodically because they do come loose.  I check all the put-together stands once a year and I've quit being surprised at the loose nuts and bolts on those things. Even with start washers or lock washers - vibration normally wins.

[tonylumps]

Yes i would love to bolt that Hegner  and EX Stand down to my concrete garage floor .But I do move them from time to time. It is amazing what 50 pounds of sand will do to these saws

Edited February 9, 2018 by tonylumps