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Author Topic: Plunge Saw Advise  (Read 19145 times)

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Offline innovative3

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Plunge Saw Advise
« on: August 31, 2011, 08:34 AM »
Need advice on which plunge saw to purchase. We are a custom cabinet shop, making high end furniture and cabinets. Just used one of our installer's 55 for a job, thoroughly impressed. As a matter of fact sold. I would see the 55 as enough saw for our needs, however I hate purchasing twice. Most of this would be for sheet stock, however we manufacture doors and other solid wood products. Anyone have advice on capacity, capability or experience?

We have a stock shop with equipment, however this would bring a convenience to the bench.

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Offline Holzhacker

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Re: Plunge Saw Advise
« Reply #1 on: August 31, 2011, 08:47 AM »
Talk about opening up a debate. This question has been kicked around more times than the scrawny kid in a grade school. If you do a search you'll find threads with a plethora of replies. I'm sure others will chime in here as well.
I have the TS75 because I cut about 1/2 and 1/2 lumber and sheet goods. I could probably get by with the 55 but why would I want to. Hate the idea of not having a big enough saw. Kind of like doing a porch job without a wormdrive. There are times though when making repeated rips on sheet goods that the smaller size and weight of the 55 seems like it would be nice. Unless you are dealing with vintage wood, vintage fat doors or thick stock high end work, the 55 would probably do you well.
Good luck and welcome to the FOG.
"The Code is not a ceiling to reach but a floor to work up from"

Offline Festool USA

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Re: Plunge Saw Advise
« Reply #2 on: August 31, 2011, 09:09 AM »
Welcome to the forum. I'm sure members will weigh in on the topic and this has been discussed on here quite a few times already. But, a quick rule of thumb is: will you be cutting materials thicker than 1-15/16"? If so, the TS 55 will not be the right saw for you. If not, then I would recommend going with the 55 which will be capable of cutting materials that thickness, including solid hardwoods. The 75 is a much bigger saw (weight, size).

Remember, Festool offers a 30-day, no-hassle money back guarantee on tool purchases. Get one, try it. If it's not the right saw for you, just go back and swap it out for the other.  [wink]

If you have more questions, feel free to contact me directly at sho@festoolusa.com.

Thanks,
Shane Holland
Festool USA

Offline fdengel

  • Posts: 854
Re: Plunge Saw Advise
« Reply #3 on: August 31, 2011, 09:25 AM »
I figure if I need to cut anything thicker than my TS55 can handle, I'll either use a hand saw, or wait for the Carvex to come out and use that...


Offline Tom Bellemare

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Re: Plunge Saw Advise
« Reply #4 on: August 31, 2011, 10:24 AM »
The 55 is the cutting depth in mm. If the saw is vertical, it can cut 55mm OFF THE RAIL. The rail accounts for 5mm, which leaves 50mm or, as Shane stated, ~1-15/16".

If you use the saw at 45 degrees, and I do periodically so I suspect you will also, you have about 37mm reach on the rail. That is ~1-7/16". If you're making furniture, I think that less than 1.5" is what you should really be thinking about because I suspect you will use the saw at 45 degrees reasonably often.

The TS 75, on the other hand will cut 70mm deep straight down on the guide rail and ~55mm deep at 45 degrees. Those translate to ~2-3/4" straight and ~2-1/8" at 45 degrees.


Tom

Offline waho6o9

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Re: Plunge Saw Advise
« Reply #5 on: August 31, 2011, 11:21 AM »
The added capacity of the larger saw is unsurpassed.  Get the TS75, you won't regret it.  Breaking down several sheets at a time is awesome.  Yeppers.    [smile]

Offline RL

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Re: Plunge Saw Advise
« Reply #6 on: August 31, 2011, 11:42 AM »
I am a 55 owner, but I would recommend the 75 unless you are planning to cart the saw around. If it is going to be used in your shop most of the time, the 75 would give you more flexibility.

Offline Alex

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Re: Plunge Saw Advise
« Reply #7 on: August 31, 2011, 11:47 AM »
I'd go for the 75 too. I don't mind a bit of extra weight but I do mind weak saws. We get a lot of reports of the 55 bogging down on easy cuts. Before I ever heard of the TS55 or Festool I already disliked saws with less than 1500 watts power.

Offline davee

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Re: Plunge Saw Advise
« Reply #8 on: August 31, 2011, 11:55 AM »
I have both and use the 55 the vast majority of the time.  It was my only plunge saw for several years and worked fine (cabinets, furniture, etc.).  I do like the 75 for 8/4 hardwood, but really like the light weight of the 55 for most activities.  If I had to stick to only one saw, it would be the 55.

Sorry...just had to be contrary.

Offline RvB

  • Posts: 225
Re: Plunge Saw Advise
« Reply #9 on: August 31, 2011, 12:05 PM »
Mafell mt-55 is the tool for you.. More power, cleaner cuts
And better dust collection!!

Greets
ALLREADY GOT: - Domino DF 500Q set - CS70 precisio - Kapex 120 EB set - TSC 55 REBI plus SCA - TS 55 EBQ  - EHL 65EQ - PS 300 EQ - PS 420 EBQ - Vecturo OSC 18 Li -   - OF 1010 EBQ - OFK 500Q R3 - CTL 26 SD E/A - CTL Midi - CTL MIDI I - DTS 400 EQ - ROTEX 150 FEQ - ROTEX 90 EQ - T 18+3 -  CXS Li 1,5 set x2 - FS 1400/2 x3 - FS 1400/2 - FS 2700/2 - FS 3000/2 - FS 800/2 - FS Bag

D 36 HW RS craftsman cleaning kit - D27/D36 portable cleaning kit - RO90 & DTS 400 abrasive sys - carpenter sys - Fein supercut sys - homemade drills&drivers sys - nailguns sys5 - SYS-ToolBox1 x 2 - SYS-ToolBox2 x 2 - Sys-StorageBox - SYS-CART RB-SYS

WORKIN' REALLY HARD FOR: ETS 150/3 - one extra DTS 400,one extra cxs, PSC 420 eq, centrotec sys, T18+3 PDC18/4, BHC 18.

Offline Tom Bellemare

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Re: Plunge Saw Advise
« Reply #10 on: August 31, 2011, 12:12 PM »
Another advantage of the TS 75 over the TS 55 that often is left unmentioned...

If you want better gas mileage, a convertible, or just more room in the garage, the TS 75 has a steel cutting blade.


Tom

Offline Greg in Memphis

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Re: Plunge Saw Advise
« Reply #11 on: August 31, 2011, 12:24 PM »
I originally purchased the TS-75. It has more capacity, more power and better dust extraction. It is absolutely my favorite circular saw ever. It is also more expensive.
The saw is as big and heavy as a small sewing machine, but the cuts make it well worth all the hassle.
 
I bought a TS-55 demo when a local lumber company was going out of business, and since then, the TS-55 is the saw I almost always use. The difference in weight and ease of use and setup (compared to the TS-75) offsets the decreased capacity and power most times.

I still like my TS-75 better, it's just that the TS-55 is easier to pick up and place on rails all day long because of it's lighter weight and smaller footprint.

If I could only get one, I'd get the TS-75. That said, both saws are worth every nickel and then some.

Hope this may help
 

Offline Hans Mertens

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Re: Plunge Saw Advise
« Reply #12 on: August 31, 2011, 01:33 PM »
I myself have 55 and since yesterday I bought my boss (with his money) a 75.

We've been using my 55 the last six months for making stairs, cutting a lot of Rubberwood panels 33 and 44mm thick.  The 55 with the Panther-blade, did the job but I noticed it struggled sometimes.  Been using the 75 today with a Panther-blade and there's a big difference, both in weight and power. 
The 75 has the power to be used like this all day long, but it's also heavier machine to use all day long.  I'm glad I decided for the 75 for this use, cutting solid wood panels up to 44mm but I'm equally happy with my 55 when I'm on the road and need to cut plywood and MDF.

Offline MrToolJunkie

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Re: Plunge Saw Advise
« Reply #13 on: August 31, 2011, 08:22 PM »
I have the 75 and love it -- it is perfect for working with thick hardwood.  The 55 is a great saw too and I have used it in some of the end-user classes...I like the weight, but it seems to lack power when pushing it hard whereas the 75 never seems to slow down...that is just my experience with the limited use of the 75.  Both saws cut super clean and have awesome dust collection.

Scot

Offline fdengel

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Re: Plunge Saw Advise
« Reply #14 on: September 01, 2011, 10:59 AM »
If you're making furniture, I think that less than 1.5" is what you should really be thinking about because I suspect you will use the saw at 45 degrees reasonably often.


When I was starting to think along those lines, it dawned on me that the only thing I'd be likely to cut with any frequency at an angle that was that thick would be 2x lumber, and I have a mitre saw for that.  I can't tell you the last time I tried to cut a 2x at a 45 degree angle along its length...

Offline allen r austin

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Re: Plunge Saw Advise
« Reply #15 on: September 26, 2011, 10:35 PM »
well let me put in my 2 cents worth, one is not just bigger than the other , they are for 2 different jobs.The 75 runs slower-more hp
the 55 runs faster better cut( 2 times the teeth per sec.) and last= what ever saw you get , you will want the other at some point in time.
expensive , how much did the one cost that doesn't work?

Offline Peter Halle

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Re: Plunge Saw Advise
« Reply #16 on: September 26, 2011, 10:37 PM »
Allen,

Glad to see you posting.  You have a lot to offer!

Peter
« Last Edit: October 09, 2011, 09:29 AM by Peter Halle »

Offline Festoolfootstool

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Re: Plunge Saw Advise
« Reply #17 on: October 09, 2011, 08:52 AM »
Mafell mt-55 is the tool for you.. More power, cleaner cuts
And better dust collection!!

Greets


+1 [thumbs up]
If the milk turns out to be sour, I ain't the kind of **** to drink it.......

Why do Festool accessories only have a two month guarantee here in the UK ?

Offline RL

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Re: Plunge Saw Advise
« Reply #18 on: October 12, 2011, 10:42 PM »
well let me put in my 2 cents worth, one is not just bigger than the other , they are for 2 different jobs.The 75 runs slower-more hp
the 55 runs faster better cut( 2 times the teeth per sec.) and last= what ever saw you get , you will want the other at some point in time.

Allen,

Are you just looking at the RPM when you say the TS55 runs faster? The TS55 has an RPM range of 2000-5000 and the TS75 has a range of 1350-3550 RPM, but because the diameter of the TS75's blade is 8 1/4" versus 6 1/4" for the TS55, the teeth at the edge of each saw are covering different distances for the same RPM.

Happy to stand corrected if I am wrong.

Richard.

Offline Dovetail65

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Re: Plunge Saw Advise
« Reply #19 on: October 12, 2011, 10:53 PM »
Nope, you are correct. A larger blade(larger diameter disc) has a faster tip speed(edge) for the same RPM.  I had both saws and the TS 55 does not have a better cut quality at all. Actually, I personally could not tell the difference in the cut, only the power when the wood got thicker.

I am not positive, but I think: RPM X Pi X  Diameter / 60  equal tip speed.  That's from memory we need to look it up.

Which means at max rpm  the tip speeds are virtually identical(well very close). This can not be by accident.

Someone not so many years out of school can maybe verify or someone that still works in a science field.

TS 75 : 3550 *3.14*4.25 / 60 = 789.58  oops I used the radius you guys are supposed to be watching me!

TS 55 : 5000*3.14*3.125 / 60 = 817.70  oops I used the radius I guess the nub will just double then

I think this is better:

3550 *3.14*8.5 / 60 = 1579

5000*3.14*6.25 / 60 = 1635


If this is true I do not think this difference is nearly big enough make any noticeable difference at all in cut quality.

If I am way off base here just let me know and fix it, I'll change the calculations to make them correct.  :)

As a side note that big 8 1/4 blade moving at 5500 RPM produces a tip speed that is most likely dangerous. 5500 * 3.14 * 8.5 / 60 = 2446!

Think about it, the larger the circular disks diameter the faster the outer edge speed will be because it is covering more distance  during the same amount of time. So Rpm is only a good comparison for diameters of the same size.

Maybe Rick Christopherson can take a look at this and make corrections or correct the theory behind it if needed.


« Last Edit: October 13, 2011, 12:02 AM by Dovetail65 »
The one who says it can't be done should avoid interrupting the person doing it.

Offline Alex

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Re: Plunge Saw Advise
« Reply #20 on: October 13, 2011, 04:45 AM »
Dovetail, your reasoning and calculations are correct.

Only addition I'd like to make to them is that the max RPM of the TS55 is 5200 not 5000. When you enter that in the calculation you will find that a tooth on the TS75's blade runs roughly 20% faster than that of the TS55.

But is that 20% speed difference enough to make up for the number of teeth that pass a certain spot?

Because Allen is also correct when he says that double the number of teeth pass a certain spot with the TS55.

The TS55 comes with a 48 teeth blade and the TS75 with a 36 teeth blade.

Now lets assume the blade of the saw is running at full speed and the saw is not moved by the user, then for a set point on the workpiece:

with the TS55: 5200 x 48 = 249.600 teeth will pass in 1 minute.
with the TS75: 3550 x 36 = 127.800 teeth will pass in 1 minute

That means roughly double the number of teeth for the TS55.  

So the TS75's teeth move a little faster but there's only half the number of teeth of the TS55 cutting into the workpiece.

Does that mean these numbers have a huge influence on the quality of the cut? Not necessarily. As Dovetail reports from his own experience, there is little noticeable difference and I think first hand experience says more than some theoretical calculations.


 
« Last Edit: October 13, 2011, 08:14 AM by Alex »

Offline Dovetail65

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Re: Plunge Saw Advise
« Reply #21 on: October 13, 2011, 08:24 AM »
Hey I remembered something from school!

Yes, when I was using both saws they both cut flawlessly and I agree any tool needs to be used to really know. Some of these specs we read on certain tools are laughable(net necessarily Festools) and don't mean much.

I do think that maybe the TS 55 is suited to plywood or a few pieces stacked and the the TS75 suited to harder, thicker woods and gang cutting of stacks of plywood, maybe that's how they could be differentiated for different uses.

I always preferred the TS 75, that's why I sold the TS 55.  I now do see  if only cutting plywood or just a couple stacked pieces for most of the work that the TS 55 would be preferable to some.

Both always worked great for me and I never grabbed one over the other to get a better cut when I did have both. I usually just used the TS 75, so that's the one I kept.

As you point out those are the stock blades and I think the 75 is expensive so they give the cheaper less toothed blade with it, I can easily throw on a 52 tooth blade on the TS 75.

I think its better to compare the blades with the same amount of teeth which puts the 75 at a closer teeth per minute as the 55, but I do see value in comparing what initially comes with the saw. Out of all my power saws the Festool are about the only saws I did not chuck the stock blade and get a new one right off.

I see how your calculations are correct, but I do not think that is what is most important in comparing the blades cut quality. I believe the edge speed of the blade plays a crucial role in it.  I believe(possibly incorrectly) you need to use the edge speed of each diameter blade to compare becasue the speed of the carbide passing through the wood will make a difference in cut quality. Generally, not always, in wood the faster the carbide slices through wood the smoother the cut, just as the more carbide passing through the cut produces a smoother cut. At least that is my experience in ply. I use the saw on its fastest speed to get the best quality cut in ply.  I think this idea of edge speed is why the TS 75 cuts as well as the TS 55 with a lower RPM in actual use. Well, its my thought on it anyway.
« Last Edit: October 13, 2011, 08:48 AM by Dovetail65 »
The one who says it can't be done should avoid interrupting the person doing it.

Offline JSands

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Re: Plunge Saw Advise
« Reply #22 on: October 26, 2011, 01:03 PM »
Since this thread will prob. float around for awhile.....

I will re emphasize what a few other posters mentioned....

I went with 75...glad I did.... the only reason I would buy a 55 is for.... single cut sheet goods, such as 3/4" thickness max.

The beauty of the 75 IMO it can handle 2 pieces of wood at once (certainly not overkill though, remember, these are 120V hand tools).    Festool squeezed as much power as posssible out of 120V hand tool in this saw.   And when cutting through 3/4" hardwood double stacked, the saw is at its limit, you are forced to reduce speed of cut....but its fast enough to prevent burns, so, IT WORKS!    Very impressive for making long straight cuts....

I have found, its rare I need ONE of something, two is common...to assure two identical sized pieces, I stack them make and make one cut.   This saves time, but it also ASSURES you two identical cut boards....   which is prob. more important to me, as the risk of mistakes, is quite costly in material.   NO matter how hard you try, its hard to cut to 2' x 6' pieces identical in size unless they are stacked cut.... to many variables that go askew.    This is most useful when you don't need a high precision dimension, but instead, you just want identical sized finished pieces.

so add that to your decision process.... 

the value of the TS55 is also weight, if you use an MFT, and cut thin sheets, the 75 is a bit big n heavy.... but that is non-issue for me, as anything small, I use a TS for.   So what you currently own also fits into the decision equation.     The TS75 is my sliding table saw, that folds up small and disappears...  We are not high production, so we are not cutting sheets all day, the TS75 w/ rails is really the ultimate portable Sliding TS replacement...  a well engineered and well thought-out product.

 

Offline Festoolfootstool

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Re: Plunge Saw Advise
« Reply #23 on: October 26, 2011, 01:14 PM »


Jsands

sounds like you need the parallel guides
If the milk turns out to be sour, I ain't the kind of **** to drink it.......

Why do Festool accessories only have a two month guarantee here in the UK ?

Offline JSands

  • Posts: 194
Re: Plunge Saw Advise
« Reply #24 on: October 26, 2011, 02:21 PM »
I do own the parallel guides, and they do serve a purpose but not here....

when I am ripping down a sheet or some long boards - it's one cut in the X direction, then another cut in Y dimension.....

If I have stacked sheets, I could not make all the X cuts with the parallel guides, or I would have to lift the sheet off after the X cut, move it, cut the next one, etc.  (and this assumes they are all the same X dimension)...with my system, I slide foam under two sheets layout lines, and make two cuts and have two identical pieces without moving the wood till its at final dimension.

Putting parallel guides on and off the rail would ruin the "convenience factor" of the entire cutting system for XY cuts.

I use the parallel guides when I need 2" strips, and 40 of them, its the perfect tool for that job.... or anytime you need the same width from the same board, many times, its worth setting up the parallel guides.

For me, most of my cuts are different X and or Y dimensions.... of course, sometimes I have a handful of the same dimensions such as shelves, in which case I use one of my first double stack as the measuring stick for the next ones.... ultra fast, and "almost identical dimension"....you might feel the difference with your finger when you align them, close enough for most ww tasks, specially shelves.    Anyway,  I "cut to the line",  and am assured my double stack will come out identical...now the only room for error is proper layout and assuring the bottom board does not slip, never happened yet, and when I am unsure I clamp'em...

Also, when working alone, I find it very difficult to rip 5 ft + boards through my cabinet saw.... why?   It's hard to push forward AND against the fence from behind the board.   So I often get saw marks on the board from slight changes in force, very fine, but now I need edge treatment, which also changes width... so I must account for this a bit.... with the TS75, the cuts are identical and never need treatment, although I always keep the blades sharp which helps keep the cuts ultra clean.   Now, a second person, or some jigs on the TS can change this equation a bit.... but I work alone quite often.

Even going a step further..... I no longer edge join long boards on my 12" joiner, (again 4ft range and longer)...Instead, I lay the rail where it needs to be,  and a "single" cut, faster, perfect edge (vs. tons of swipes on the joiner)  ..... then, draw a few width lines, mark long rip line, set rail, and cut.   Now two identical sized boards of perfect rip dimension ....  its the easiest method I have used.... no more changing joiner blades from edge joining, which wears the blade near the fence, making face joining uneven.   The rails solve this problem as well.... sort of "joiner blade savers"...   :-)   Much of the hard wood I buy, needs a lot of edge joining...getting rid of that swipe, swipe, swipe task has saved my wrists, arms, shoulders, etc. as some of these long boards can weigh 40+ lbs...

Thanks for caring Festool  :-)


   
IMO, I don't think the Festool rail system is marketing well....it can do so much, but many people never think of many of the applications.... luckily I learned from a few Festool employees... who are more than helpful.   This tips have simplified, improved, sped-up,  and have reduced potential for errors in my workflow....  Kudos to Festool tools, AND Festool employees, in this case, its a mix of a great tools and great application of the tools which requires some education....and no, I have not drank the Green Kool Aide... I have lots of tools from many different makers.... When Festool is the right tool for the job, I buy it, use it..... 



Offline JSands

  • Posts: 194
Re: Plunge Saw Advise
« Reply #25 on: October 30, 2011, 11:29 PM »
to make my position complete...I left this out...

when making long cuts, IMO, a single long rail is imperative to assure straightness....
while you can join rails, the cuts are not assured straight, as even when you set them to a long straight edge, they move when handled often, and only a slight movement can throw off your straightness....which is what makes the system so great...  this is important, and at $300 for a long rail, it sure adds to the costs, but now you will always have extremely straight cuts.   Of course, this is best in a shop, as these long rails can be cumbersome to bring to a job site...

Offline Ken Nagrod

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Re: Plunge Saw Advise
« Reply #26 on: October 30, 2011, 11:40 PM »
I haven't had any problems keeping joined rails straight.  There's definitely an extra time factor in checking the joined rail combo for every cut, but it works fine.  I know with the longer FS3000 and FS5000 rails, it's more difficult to get a perfectly straight cut out of them because the aluminum extrusions are so long and allowable tolerances are a factor.  As an example, how many of you have the FS3000 and know that it's 1/32" out in the middle.  That's within Festool's tolerance, yet when you cut a sheet of ply down the 8' length twice per cutoff, your piece is now 1/16" narrower in the middle than at the ends.  Does that matter?  That's for you and maybe your customer to decide.

Offline JSands

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Re: Plunge Saw Advise
« Reply #27 on: November 01, 2011, 11:20 PM »
Valid point Ken...   

I prob. got lucky with my long rails, as they are out way less than a 64th over 8ft....  never bothered to check how much, as that is pretty darn good....but at the same time, others can get long rails that are further out, but yet, still within Festool Tolerances...   where did you get this Festool "tolerance value"  ?

My problem with joining rails was, during multiple cuts, it appears that if one person sets the rail on-end too hard, it would rock the connection just a tad, but when that connection is in the middle, it can throw the cut off dramatically...   I found myself constantly checking to see if the rails moved....    A lot of this comes down to, who is doing the work....if its just "you" and you  "as a Festoolian" are constantly aware of these issues, chances of errors are less likely.  If you get a crew started, and then turn it over to them, it seems few care as much as us about these details...  more probability of errors...


Offline Ken Nagrod

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Re: Plunge Saw Advise
« Reply #28 on: November 01, 2011, 11:39 PM »
David McGibbon at Festool told me they were in acceptable tolerance at 1/32" out.

Offline Tom Bellemare

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Re: Plunge Saw Advise
« Reply #29 on: November 02, 2011, 12:34 AM »
If I take a 3-meter long, thin piece of aluminum, it is going to flex.

If that piece of aluminum has various structural components that will also help keep it aligned, I might be able to make a straight line over 3 meters with that tool...


Tom

Offline JSands

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Re: Plunge Saw Advise
« Reply #30 on: November 02, 2011, 11:50 AM »
1/32" over what distance?

Also, the rails "rail" or "hump" is a good, but not perfect, means to keep the rail straight.... Of course, within the limits of the real world practical use for what they were intended for... ya have to treat these rails gentle...

I think Festool designers were balancing weight considerations vs. rigidity.     
« Last Edit: November 02, 2011, 12:01 PM by JSands »

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Offline Ken Nagrod

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Re: Plunge Saw Advise
« Reply #31 on: November 02, 2011, 07:33 PM »
We were discussing the FS 3000 and FS 5000 guide rails.  You'd have to ask him about the acceptable tolerance on the shorter length rails.

Offline JSands

  • Posts: 194
Re: Plunge Saw Advise
« Reply #32 on: November 02, 2011, 07:58 PM »
so on the 3000,  1/32nd / 10ft is 1/320th, or .003" per ft, decent....

on the 5000,  .002" per ft.... even better.... 

from my experience, they are prob. closer to 1/64th...

Problem is, my Starett Straight edge (the longest straight edge I own) is only 6ft...
hard to find a suitable reference edge...


Offline Ken Nagrod

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Re: Plunge Saw Advise
« Reply #33 on: November 02, 2011, 08:01 PM »
David was saying that 1/32" variance over those longer lengths is acceptable from the aluminum extrusion process.  He didn't state what the tolerance was exactly.  A spec like that might have to come from Germany.

Offline Tom Bellemare

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Re: Plunge Saw Advise
« Reply #34 on: November 02, 2011, 08:46 PM »
1/32" is 31 thousandths and change. That's not much over a long distance, especially if the object being measured is not milled.

I have designed a lot of metal parts where +/- 15 thousandths was the default tolerance for machining. I wouldn't consider 30 thousandths to be out of consideration for a 4' extrusion.

Absolute dimension definitions help the manufacturer and the designer meet the requirements of the tasks for which something is intended. Using that method, the overall requirements are defined and the mfr. is allowed more leash. If David is referring to an absolute dimensional requirement, it makes sense that the length of the rail doesn't matter.

My experience with Festool Guide Rails is that they are really accurate if used properly and never abused prior to use. As I stated in a previous post, I can bend aluminum. If the rail, which has a sticky strip component on the bottom, is place on the work piece under stress, it can be crooked. The key, even with shorter rails, is to relieve all stresses as they are placed on the work piece.


Tom

Offline Ken Nagrod

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Re: Plunge Saw Advise
« Reply #35 on: November 02, 2011, 08:52 PM »
1/32" is 31 thousandths and change. That's not much over a long distance, especially if the object being measured is not milled.

I have designed a lot of metal parts where +/- 15 thousandths was the default tolerance for machining. I wouldn't consider 30 thousandths to be out of consideration for a 4' extrusion.

Absolute dimension definitions help the manufacturer and the designer meet the requirements of the tasks for which something is intended. Using that method, the overall requirements are defined and the mfr. is allowed more leash. If David is referring to an absolute dimensional requirement, it makes sense that the length of the rail doesn't matter.

My experience with Festool Guide Rails is that they are really accurate if used properly and never abused prior to use. As I stated in a previous post, I can bend aluminum. If the rail, which has a sticky strip component on the bottom, is place on the work piece under stress, it can be crooked. The key, even with shorter rails, is to relieve all stresses as they are placed on the work piece.

Tom

Who's gonna pay for all that therapy or should I play one of those crashing waves cd's for my guide rails?

Offline Tom Bellemare

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Re: Plunge Saw Advise
« Reply #36 on: November 02, 2011, 08:55 PM »
Go to Hawaii...


Tom

Offline andvari

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Re: Plunge Saw Advise
« Reply #37 on: November 02, 2011, 10:17 PM »

A 12' straight edge for checking runway flatness goes for $1500 or so. It is spec'ed +/- 0.012" Maybe with one of these you could get the straightness you are looking for.

TS55, Domino 500, Domino Assortment, OF1400, CT36+Boom Arm, T12+3, FS3000, Parallel Guides, RO 90, ETS 150/3, Domino XL, Domiplate, LS130, RTS Guide Stop, CMS-GE, Carvex 420

Offline JSands

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Re: Plunge Saw Advise
« Reply #38 on: November 02, 2011, 10:56 PM »
>  A 12' straight edge for checking runway flatness goes for $1500 or so. It is spec'ed +/- 0.012" Maybe with one of these you could get the straightness you are looking for.

           
                      Not sure who you were responding to....but if it was me, as I wrote above, I am more than happy with my 64th over 8ft, for the cost of the rail, ya can't ask for more in ww......  possible you were responding to another poster, or did not read the thread....

But I am curious of the straight edge you refer to of that length and cost?   Got a link?   
My guess is, at 12' it would be hard to keep the straight edge "straight" as just the weight of it alone would make it change dimension a bit...?

Offline RL

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Re: Plunge Saw Advise
« Reply #39 on: November 02, 2011, 11:15 PM »
Piqued my interest so I did a search on the subject...

http://www.concentric.net/~Petsch/Runway/RunwayStraighEdge.htm


Offline JSands

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Re: Plunge Saw Advise
« Reply #40 on: November 02, 2011, 11:31 PM »
Great find Richard!   thx for posting, very interesting web page...

>  0.012-inch maximum deviation over 144 inches


that breaks down to about a thou per ft....  darn good considering the length... and tremendous light weight...  for 12ft, 25 lbs at 1x4" dimension.... 

at $1700 delivered, shows the value of Festool long rails...



Offline Ken Nagrod

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Re: Plunge Saw Advise
« Reply #41 on: November 02, 2011, 11:47 PM »
I'm getting one.  I'm going to check everything under the sun.

Offline JSands

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Re: Plunge Saw Advise
« Reply #42 on: November 03, 2011, 09:34 AM »
in forums, its hard to extrapolate humor / sarcasm....

are you really getting one, if so, for what?

gotta admit, it is a cool find....can't think of any ww applications I do that would justify that price....
but if I had one, or access to one, I would prob. start checking stuff just for curiosity....

Offline wooden

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Re: Plunge Saw Advise
« Reply #43 on: November 03, 2011, 10:25 AM »
I'm getting one.  I'm going to check everything under the sun.

My friend has an SCMI jointer.  Beds are literally large enough to land a jumbo jet and flatter than lake Avalon on a windless day.

I was shocked to learn that my 2x10 lumber is out by 2548 inches over 8 feet of length!!!!!!!!!

Offline greg mann

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Re: Plunge Saw Advise
« Reply #44 on: November 03, 2011, 11:16 AM »
There was a 'discussion' over on Sawmill Creek about router table flatness and the term +/-.002 was invoked by router guru Pat Warner. I posted a comment that flatness should not be described as a +/- tolerance as it adds confusion to the discussion. The same is true for straightness, perpendicularity, parallelism, roundness, cylindricity, and so on. In all cases where one is describing a geometric form tolerance, zero represents perfection and the deviation is always described as a positive value. Why does it matter? Well, when one says +/-.002 do they mean .002 total variation (supposedly either plus or minus) or .004 total (from one extreme to the other)?

As an example, one can describe straightness more accurately by saying a rail is .010 out-of-flat in a concave or convex condition, or, that the rail is .010 OOF in both (snake shaped).  Then, there can be a discussion about which condition may be more desirable and when. In the case of a router table I would suspect that being convex, with the area immediately surrounding the bit being the highest spot, would be the most desirable form of deviation. For a rail it probably makes little difference, with one case being better sometimes and the other case being better on another occasion.

I asked Pat to clarify what he meant but so far I did not get a direct answer. He did say that his RT was flat within .002 within a 10 inch circle around his bit, so I am going to interpret that to mean he thinks a flatness within .002 total is acceptable. If that is the case, and he wants to continue to use +/- terminology, then he should at least change his description to +/- .001. How much clearer might it be to just say .002 total variation?
Greg Mann
Oakland, Michigan

Offline greg mann

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Re: Plunge Saw Advise
« Reply #45 on: November 03, 2011, 11:17 AM »
1/32" is 31 thousandths and change. That's not much over a long distance, especially if the object being measured is not milled.

I have designed a lot of metal parts where +/- 15 thousandths was the default tolerance for machining. I wouldn't consider 30 thousandths to be out of consideration for a 4' extrusion.

Tom

Tom gets what I mean.  ;D
Greg Mann
Oakland, Michigan

Offline Alex

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Re: Plunge Saw Advise
« Reply #46 on: November 03, 2011, 12:39 PM »
Well, when one says +/-.002 do they mean .002 total variation (supposedly either plus or minus) or .004 total (from one extreme to the other)?

+/-.002 means it can be .002 in either one direction or the other, so a possible total of .004.

Offline JSands

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Re: Plunge Saw Advise
« Reply #47 on: November 03, 2011, 04:09 PM »
Gregs point is, for flatness, its simply a given value from flat.....

Thicknesses are +/- tolerance values...

router table flatness matters.... I have done lots of edge working that never comes out as perfect as I would like...the reason is, the flat piece takes on the unevenness of the table...
when something is critical, I use a trim router, as the base is over a small area of the piece being routed....

Offline Ken Nagrod

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Re: Plunge Saw Advise
« Reply #48 on: November 03, 2011, 06:53 PM »
in forums, its hard to extrapolate humor / sarcasm....

are you really getting one, if so, for what?

gotta admit, it is a cool find....can't think of any ww applications I do that would justify that price....
but if I had one, or access to one, I would prob. start checking stuff just for curiosity....

Sarcasm.  If I had one, I'd most likely go nuts finding imperfections in everything.  [big grin]

I don't understand what's so hard about understanding what tolerance means? [unsure]  Alex gets it.

I've seen tolerances also expressed in something like this manner:  +0.002" / -0.006".     When the deviation is the same in both directions, then there's no need to write +0.002" / -0.002" instead it's expressed simply as +/- 0.002".
« Last Edit: November 03, 2011, 07:00 PM by Ken Nagrod »

Offline pugilato

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Re: Plunge Saw Advise
« Reply #49 on: November 03, 2011, 08:12 PM »
you should try the mean +/- one standard deviation of the population of measurements, which is a typical measure of uncertainty.  That's when it starts getting fun...

Offline greg mann

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Re: Plunge Saw Advise
« Reply #50 on: November 03, 2011, 11:43 PM »

A 12' straight edge for checking runway flatness goes for $1500 or so. It is spec'ed +/- 0.012" Maybe with one of these you could get the straightness you are looking for.



Well, here ya go. Andvari references a runway flatness gauge and says it is spec'd at plus or minus .012".  Not so. The actual tolerance of the gauge is .012 TOTAL, which is, of course, half as much deviation. My guess is that making a runway flat to .125" per 12 feet is an order of magnitude more difficult than .250" per 12 feet.

All I am suggesting is that we clarify what these values really mean when we use them. When we say plus or minus are we really implying the total deviation or are we just being careless? The difference is not insignificant. Like the difference between one inch and two.

Greg Mann
Oakland, Michigan

Offline greg mann

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Re: Plunge Saw Advise
« Reply #51 on: November 03, 2011, 11:54 PM »
Well, when one says +/-.002 do they mean .002 total variation (supposedly either plus or minus) or .004 total (from one extreme to the other)?

+/-.002 means it can be .002 in either one direction or the other, so a possible total of .004.

This is true when you are referencing size, like diameter or thickness, but it is not helpful for geometric features where perfection is represented by zero deviation. Without special clarification, such as concave or convex, in which either would be described as a plus value, tolerances of form are always uni-directional. In your example, Alex, the tolerance should be described as .004. If it is used to describe straightness.
Greg Mann
Oakland, Michigan

Offline Tom Bellemare

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Re: Plunge Saw Advise
« Reply #52 on: November 04, 2011, 12:21 AM »
Greg:

I'm not sure a GD&T discussion is valuable here... or maybe it is.


Tom

Offline JSands

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Re: Plunge Saw Advise
« Reply #53 on: November 04, 2011, 12:52 AM »
Greg is nutz on.....


Offline Ken Nagrod

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Re: Plunge Saw Advise
« Reply #54 on: November 04, 2011, 01:16 AM »
Ok, I just fixed it.  Greg is now banned from all woodworking forums and anything that uses the word "wood".  All he'll see is an empty vortex on his screen.  Now everyone else can relax.  We are back at DEFCON 5.  [cool]