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Author Topic: bent guide rail...  (Read 15337 times)

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Offline panelchat

  • Posts: 190
bent guide rail...
« on: August 18, 2009, 01:50 AM »
I bought a (second!) TS 55 about two months ago and had some oddball trouble doing some very easy cuts. i found that the 55" rail was bowed out at the center by about 1/16".  !  this error compounded throughout the workpieces enough to basically ruin them before i saw what was happening. i returned it and the sales guy ended up calling his service contact about it, who confirmed that on rare occasion he had encountered bent rails. i've designed/worked with extrusion profiles before and know how hard it is to get them true after they come out of the extruder- the tolerances are actually a bit on the loose side. the rail i had and the box it came in showed no signs of impact/damage whatsoever, so i'm pretty sure this component was faulty from the factory.

So i'm wondering if anyone has seen this before, even to a lesser degree, and whether or not guide rails tend to be truly dead on straight or not- for future work I hope to have the option of using a 90 degree setting to use the rail to get very square panels for jobsite built casework, basically bypassing the Martin panel saw in the shop. This won't work so well if the guide rails have any deviation.

(i got a replacement for mine but it is on a distant jobsite for a while and i haven't had time to check it out yet...)

Any experience with this?

Thanks...


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Offline Graham

  • Posts: 9
Re: bent guide rail...
« Reply #1 on: August 18, 2009, 06:35 AM »
I bought two 1.4m rails about 6 months ago and one of them has a bow in it (similar to yours).  Like you it took me a while to realise as I am a hobbyist, so not using the equipment all the time, and I was only using the second rail (attached to the first) when breaking down large sheets.  Like you I only discovered the problem when I used the bent rail for the final cut on some oak and could not work out why my peices did not fit together  cleanly.  I ended up purchasing an enginered straight edge to check it (and other things).  For info my second rail is pretty good.

Have not had a chance to discuss this with Festool or my retailer yet but my experience with Festool customer service so far  has not been great (I should point out that I am UK based)

Graham

Offline ForumMFG

  • Posts: 985
Re: bent guide rail...
« Reply #2 on: August 18, 2009, 07:03 AM »
This may seem like a stupid question but isn't the weight of the TS large enough to take the deflection out of the rail?  I notice that when I clamp a rail down on a piece of wood it bows up as well but I stopped doing it for that reason.  If you can't have any deflection what so ever while making a cut then you have to set your rail up just right which could take some time.

Offline Peter Halle

  • Global Moderator
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  • Posts: 12374
  • Remington Steele - My Third Boy
Re: bent guide rail...
« Reply #3 on: August 18, 2009, 08:06 AM »
If I read correctly, the "bend" is from side to side which would result in a deviation in width of a cut piece.  A deviation in this manner could result in a doubling of the error when two pieces are joined edge to edge.

Peter

Offline ForumMFG

  • Posts: 985
Re: bent guide rail...
« Reply #4 on: August 18, 2009, 08:07 AM »
Okay,  I thought the bend was from front to back long ways.

Offline wnagle

  • Posts: 502
Re: bent guide rail...
« Reply #5 on: August 18, 2009, 08:20 AM »
I had the long 3000 rail and after reading a post on here, I checked ant it was off too and not straight.  I hadn't used it much or checked it up to that point.  I only checked it because i had heard of a few others on here having bent rails.  Mine hangs on a nail in my shop and has never been transported or used by anyone else, so I believed it was a defect in manufacturing. 

So I mentioned it in a post here on the FOG and McFeely's saw the post, they called me and replaced it before I had a chance to ask.  When is the last time a dealer called anyone to replace a piece of defective equipment?  Especially an internet order!

Hat's off to Mcfeely's for exceptional service!!!   Then new rail came a week later, I checked it and it was straight.
Wayne

 

TS 55, CT 33 x2, ROTEX 150, RO 90, DOMINO 500Q SET, TRION PS 300, OF 1400, MFT/3, ETS 150/3, KAPEX KS 120, DOMINO XL.

Offline ForumMFG

  • Posts: 985
Re: bent guide rail...
« Reply #6 on: August 18, 2009, 08:57 AM »
Whats the best way to check it if you don't have a engineers straight edge?

Offline Dan Rush

  • Posts: 603
  • Trim carpenter
Re: bent guide rail...
« Reply #7 on: August 18, 2009, 09:13 AM »
My local tool store has a straight i-beam set up for checking levels...  really, any known flat or straight surface would work.

You could also do two long test cuts, and butt the cuts together.  Any bend in the rail would be multified by two and show up as a gap.


Offline ForumMFG

  • Posts: 985
Re: bent guide rail...
« Reply #8 on: August 18, 2009, 09:14 AM »
Thanks

Offline Michael Kellough

  • Posts: 5192
Re: bent guide rail...
« Reply #9 on: August 18, 2009, 09:44 AM »
It's very unusual for a 55" rail to be bent/bowed that much. The natural flexibility of the aluminum guide rails in minimized by the width of the extrusion but the longest rails have enough cumulative flexibility that the foam strips can hold them in a slightly bent state. (try not to leave the middle in contact with the wood when you adjust the position of one end) That's another reason (that you never really know if the rail is perfectly straight) that I prefer to edge joint pairs of boards face up, so the bend in the guide rail matches on both boards.

Offline panelchat

  • Posts: 190
Re: bent guide rail...
« Reply #10 on: August 18, 2009, 11:15 AM »
thanks for the answers so far- i checked mine initially by drawing a line on a long sheet using the backside of the rail as a ruler, then flipped it around, matched the the ends, and drew again- it resulted in a "football" shape, showing 2X the deviation. the bend was actually a bit under a 1/16", but this little bit made it semi unusable for casework.

i designed a modular RTA furniture system a few years back that was based on a proprietary extrusion profile we drew up, so i got way in to tolerances, intricacies, etc. of aluminum extrusion during design, prototyping, manufacturing. i saw that in some cases, to get extrusions to really tight tolerances you need to get in to post extrusion machining. but with a big buget, you might be able to get around this.

my main interest concerns whether or not the guide rails always do as most extrusions do- approximate a straight line with a given tolerance. if it is always a matter of degrees with these things, one could end up having a hard time continuously getting square sheet components using this system. basically is it always a matter of degrees or can you really reliably emulate a panel saw for making cabinet parts?

certainly the saw still has a zillion applications even if the rails tend to be, say, 1/64th or 0.5mm or so out of line, but it would be nice to know that QC only approves rails so straight you can really do anything with them.

(since i don't have the saw on me i haven't been able to further check all this out...)


Offline Michael Kellough

  • Posts: 5192
Re: bent guide rail...
« Reply #11 on: August 18, 2009, 12:01 PM »
thanks for the answers so far- i checked mine initially by drawing a line on a long sheet using the backside of the rail as a ruler, then flipped it around, matched the the ends, and drew again- it resulted in a "football" shape, showing 2X the deviation. the bend was actually a bit under a 1/16", but this little bit made it semi unusable for casework.

i designed a modular RTA furniture system a few years back that was based on a proprietary extrusion profile we drew up, so i got way in to tolerances, intricacies, etc. of aluminum extrusion during design, prototyping, manufacturing. i saw that in some cases, to get extrusions to really tight tolerances you need to get in to post extrusion machining. but with a big buget, you might be able to get around this.

my main interest concerns whether or not the guide rails always do as most extrusions do- approximate a straight line with a given tolerance. if it is always a matter of degrees with these things, one could end up having a hard time continuously getting square sheet components using this system. basically is it always a matter of degrees or can you really reliably emulate a panel saw for making cabinet parts?

certainly the saw still has a zillion applications even if the rails tend to be, say, 1/64th or 0.5mm or so out of line, but it would be nice to know that QC only approves rails so straight you can really do anything with them.

(since i don't have the saw on me i haven't been able to further check all this out...)



You got it. Even with machinist's straightedges "straightness" is a specification of permissible deviation per unit of length. A precision ground hardened steel rule guaranteed to be straight within .0001" deviation per inch could be off 1/100th of an inch before it even gets packed at the factory. You won't find such a tool because it's darn hard to make, nearly impossible to ship, and impractical to use without bending it.

I think Festool has a contractor crank them out and together they weed out the bad ones so we get pretty straight tools. Your bent 55" snuck by.

Even though the guide rails can't be expected to be dead straight if used carefully they'll give you straighter results than an ordinary high quality table saw, unless you've added a dead straight 6 foot fence to the table saw (and you re-rip alternate sides of the wood a few times to completely eliminate bow. The only thing better is a sliding table saw with an 8 foot + travel.

Offline cdconey

  • Posts: 97
Re: bent guide rail...
« Reply #12 on: August 18, 2009, 12:01 PM »
Whats the best way to check it if you don't have a engineers straight edge?

Pull a string tight along the length of the rail  on each side of the guide.  As long as the guide is straight, you should get a straight cut with the saw.   I received a bent rail once, out of 12 total in my Festool 'career', but it was obvious when I received it from UPS that it had been damaged.  Called up Festool, and they handled it painlessly. 


« Last Edit: August 18, 2009, 12:51 PM by cdconey »
The dangers of cut & paste.....

Offline mshull

  • Posts: 11
Re: bent guide rail...
« Reply #13 on: March 20, 2017, 05:45 PM »

Hi.    My contractor for a new house has this problem.   He and his carpenters have discovered that one of his long rails is slightly concave -- about 1/8" -- over a 8 foot span.    He asked me about it, as I a very large number of Festool tools.    I didn't believe it at first, but he was correct.   He has putting up clear 3/4" and 1/2" maple plywood for my new shop wall and the pieces were not fitting together.   Both ends were clamped, and we changed the sacrificial strip.   It was the rail.

Mark Shull
Palo Alto, CA

Online rst

  • Posts: 2582
Re: bent guide rail...
« Reply #14 on: March 20, 2017, 05:53 PM »
When I bought my recon 55 it came with rail that was out 3mm on the last third.  I called service and three days later I had a new rail.  I use 8' 2012 - 8020 extrusions to check for straight.

Offline -woodsman-

  • Posts: 75
Re: bent guide rail...
« Reply #15 on: March 28, 2017, 12:41 PM »
I had a 55" rail, bought used with a bunch of stuff, that was crowned.  I cut at straight 2' piece off and pitched the rest.  There are times when the 24" is the most used rail I have.  The same thing had happened to a co-worker, I stole his idea.

Offline Holmz

  • Posts: 4010
Re: bent guide rail...
« Reply #16 on: March 28, 2017, 04:52 PM »
Whats the best way to check it if you don't have a engineers straight edge?

Pull a string tight along the length of the rail  on each side of the guide.  As long as the guide is straight, you should get a straight cut with the saw.   I received a bent rail once, out of 12 total in my Festool 'career', but it was obvious when I received it from UPS that it had been damaged.  Called up Festool, and they handled it painlessly.

1) Cut one side
2) Then flip the rail 180 degrees in yaw, and cut the other.
3) Then measure the width of the remaining piece.

If it is hour glass or barrel shaped, then the rail is bowed

Offline Bob D.

  • Posts: 2041
Re: bent guide rail...
« Reply #17 on: April 14, 2017, 07:26 PM »
Okay,  I thought the bend was from front to back long ways.

If it was a piece of wood it would be called a hook I believe. At least that's how I read the OP's description.

I found this thread while looking to see if anyone had ever reported a damaged MFT rail. When I opened my
MFT shipping carton (which had a nice big hole in the side, looked like the shippers had made the hole so they
could grab the box and drag it) the rail which comes with the MFT I found had a slight ding in the far end at the
hinge, and the near end the top T-track is bent as can be seen in the photos below. I was able to bend it back
carefully and the ding at the far end took some quick work with a fine cut file to remove the ding which would
have caused the saw to hang up as it passed. Unfortunately I can't check to see of the saw will ride the rail
smoothly as I received the wrong model saw and returned it today. Waiting for the TSC 55 Airstream to arrive
in the next couple days. WAs hoping to have it all this weekend since I will be very busy over the next 5 weeks
and not much time to play with new toys, I mean tools.  [smile]
-----
It's a table saw, do you know where your fingers are?

Offline paultickle

  • Posts: 2
Re: bent guide rail...
« Reply #18 on: January 08, 2021, 02:53 AM »
I have a 2.7m festool rail that is not cutting perfectly straight. It definitely bows out in the middle by approximately 1mm. I have attached an image of 2 freshly cut edges butted together and clamped lightly in the middle. You can see that the far ends of the board do not meet up by at least 1mm. This is really frustrating and is not good enough for my purposes.

Is this a normal level of error that I should expect from this rail? I have contacted festool and am waiting for a response.


Offline newellj

  • Posts: 13
Re: bent guide rail...
« Reply #19 on: April 22, 2021, 12:03 PM »
I put a 48" Veritas machinist's straight edge on a pair of LR32 rails (perfect) and the rail that came with an MFT/3 table.  The MFT/3 rail had an odd potential error.  One side of the raised section was perfect, but the side that was toward the cut was somewhat bowed.  That seems like an unlikely situation.  It's hard to get good contact with the trimmed splinter guard.  That one will need a cut to test whether it's bowed.

Offline mino

  • Posts: 378
Re: bent guide rail...
« Reply #20 on: April 22, 2021, 01:04 PM »
I bought a (second!) TS 55 about two months ago and had some oddball trouble doing some very easy cuts. i found that the 55" rail was bowed out at the center by about 1/16".  !
...

The rail you got was clearly faulty. Such a deviation is NOT OK nor normal. Even for a used rail.

Hard to say if it was damaged on transport or slipped through a QA check.

I am pretty sure such a rail would not pass a QA - unless something was missed by someone.
The Festool FS/2 series seem to have a pretty high accuracy standard. All rails I saw were within 0.2 mm (0.01") across the length when stress-free checked against a DIN Class 0 straight edge (deviation <0.05mm).


EDIT:
Important point is where you check - there reference surface is the "inner" vertical surface of the inner "rib" which is where the saw slides. The back side of the rail is not guaranteed /or needed/ to be parallel with that reference surface nor is it supposed to be an exact distance from it within the same rail.
This is why the accuracy of the TSO self-guiding connectors is limited - the ribs are not guaranteed to be exact same distance between two rails while the parallel-ness of the reference surface with the back side is usually fine, but not always. One of my rails has one end 0.1 mm "wider" compared to the other end.

This does not affect the cut precision, but is important to keep in mind when checking straightness ... as there is only one way to check it correctly.

EDIT2: added quote as the reply was to OP primarily
« Last Edit: April 23, 2021, 07:26 AM by mino »
The Machine does not have a brain. Use Yours!
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
AGC 18@AGC 125 flange, BHC 18, C 12, CTM 36, DRC 18/4, PSC 420, RS 200, TSC 55
Protool: AGP 125, VCP 260
Narex: EDH 82, EFH 36@LR32, EVP 13 H-2CA, S 57 A
My Precious: 376, 376, 376 holy, 632, 1016 holy, 1400 holy, 2520, GECKO, GRS 16 PE, GRS 16 PE

Offline newellj

  • Posts: 13
Re: bent guide rail...
« Reply #21 on: April 22, 2021, 03:10 PM »
The rail you got was clearly faulty. Such a deviation is NOT OK nor normal. Even for a used rail.

Hard to say if it was damaged on transport or slipped through a QA check.

I am pretty sure such a rail would not pass a QA - unless something was missed by someone.
The Festool FS/2 series seem to have a pretty high accuracy standard. All rails I saw were within 0.2 mm (0.01") across the length when stress-free checked against a DIN Class 0 straight edge (deviation <0.05mm).


EDIT:
Important point is where you check - there reference surface is the "inner" vertical surface of the inner "rib" which is where the saw slides. The back side of the rail is not guaranteed /or needed/ to be parallel with that reference surface nor is it supposed to be an exact distance from it within the same rail.
This is why the accuracy of the TSO self-guiding connectors is limited - the ribs are not guaranteed to be exact same distance between two rails while the parallel-ness of the reference surface with the back side is usually fine, but not always. One of my rails has one end 0.1 mm "wider" compared to the other end.

This does not affect the cut precision, but is important to keep in mind when checking straightness ... as there is only one way to check it correctly.

I was wondering about which was the reference edge.  Thanks for your post.  On the MFT/3 rail I mentioned, the reference side is nearly perfect; it's the other (outside) edge that's somewhat curved.

I know nothing about extruding aluminum but it seems a little odd that one side would be laser-straight and the other bowed?

Offline mino

  • Posts: 378
Re: bent guide rail...
« Reply #22 on: April 23, 2021, 04:34 AM »
I was wondering about which was the reference edge.  Thanks for your post.  On the MFT/3 rail I mentioned, the reference side is nearly perfect; it's the other (outside) edge that's somewhat curved.

I know nothing about extruding aluminum but it seems a little odd that one side would be laser-straight and the other bowed?
The big problem with extrusions is thermal stress during making - it is hard to maintain consistent thickness across the piece for this reason. You can however force/make a part which will have one surface straight with (most) imperfections "moved" to the other surfaces via post-extrusion cold pressing. You cannot really improve the thickness variance as easily without a milling step - which can negatively affect temperature stability with thin material in turn so is better to avoid it.

Just to confirm, by "inner" I meant the surface pointing to the center of the whole rail - i.e. the one closest to the splinter guard/cut line.
« Last Edit: April 23, 2021, 04:36 AM by mino »
The Machine does not have a brain. Use Yours!
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
AGC 18@AGC 125 flange, BHC 18, C 12, CTM 36, DRC 18/4, PSC 420, RS 200, TSC 55
Protool: AGP 125, VCP 260
Narex: EDH 82, EFH 36@LR32, EVP 13 H-2CA, S 57 A
My Precious: 376, 376, 376 holy, 632, 1016 holy, 1400 holy, 2520, GECKO, GRS 16 PE, GRS 16 PE

Offline newellj

  • Posts: 13
Re: bent guide rail...
« Reply #23 on: April 23, 2021, 06:32 AM »

Just to confirm, by "inner" I meant the surface pointing to the center of the whole rail - i.e. the one closest to the splinter guard/cut line.

Interesting and thanks, yes, that's how I understood your post - and that is the surface that was straight on the rail in question.