Parallel guides accuracy ?

[JeromeM]

@jeromem, why would having the sides tight to the piece be a problem ? Also, as far as I could tell, none of the mods that you did would seem to increase the accuracy, am I wrong ?

First point having the sides tight to the piece when the stock is long can binding so the end stops do not make complete contact on both sides. This is because the guides do not need to be at an exact 90degrees to the rail and getting them to that is not so easy. It is possible to get one guide to 90degrees and so use it an an angle guide but then the adjustment screws need to be quite tight so making removal and length adjustments less easy

There is a degree of slop in the clamping fitting that has no effect on the accuracy of repeat cuts of exactly the same width but different lengths

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here I am cutting the lids off my "2x" systainer boxes

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and as you can see it is accurate enough on 30cm and 80cm lengths to cut the tops of boxes

AFIK there is no modification that increases the accuracy of the guides themselves as they are very accurate. However that may be just semantics the modification that I made http://www.flickr.com/photos/nui-jerome/4496012364/#in/set-72157623650184949/ and the one that Wonderwino in his post http://festoolownersgroup.com/festool-tools-accessories/parallel-guide-improvements/ both make accurate setting easer. With mine you line up the back of the key with one of the cast angles with Wonderwino's you have a wider mark so could use either side.

Here is another view

 

[fshanno]

fshanno,

If your experience is the norm then I have to say I'd be a little disappointed. How would one know when or how often you'd have to recalibrate ? Maybe between sessions is enough, but it sounds like some variation could be occurring during a session as well.  Is the variability you experience in a given session  a constant amount (i.e. +1mm), or is it a proportion (say, +1mm every 20 cm) ?

At any rate, if variability of either type  is to be expected, I'd be rueing the fact that I didn't test it out before my 30-d return policy expired.

I don't think people would be happy if, say, their table saw fence varied between days.   Anyways, I'm not prepared to give up on mine yet.

Well, I'm not disappointed in the parallel guides at all.  I'm comfortable braking down $120 a sheet plywood with them. 

I just stopped worrying about fiddling with the calibration of the arms.  I did it a few times when they were new with mixed results so I gave up on trying to get perfect calibration and started doing a test rip.

The proof is in the pudding.  Starting right now, stop calibrating and leave it alone.  Make a test rip, compensate for any deviation and rip again.  I bet you'll get a perfect rip.  Or at least it will be as perfect as it can be given the nature of the stop.

Break down a full sheet and see how it goes. 

Let me add this, I do remove the arms from the guide when I'm done.  Also, I bought the guides last November and we had a cold winter and then we had a hot summer and I almost always work in a driveway. 

 

[Tinker]

RD Muller,  A great set of demos.  I am one who almost always needs to fiddle with new problems, even if the directions are written all oner it.  i appreciated that you actually showed how you had to do some fiddling to get things setup just right in some instances.  I have been hoping to afford a set of the Parallel guides for quite a while now, but something else always seems to jump to the top of the priorities list.  I had not realized just how quick and easy it is to work with them once set up and ready to go.
thanks for the input.
Tinker

 

[Tinker]

Another problem I see solved by using the parallel Guides is how easy it is to control the ultra thin pieces you are cutting.  I have been setting up backstops of sorts to capture those very thin strips from going airbourne.  Sometimes they break off at the tail end of cuts and so I make the strips longer than needed and then set up jigs for cutting to length if I am making angled corners.  It sometimes makes for quite a hastle.  You demo shows actually how easy it is to make even the thinnest slices without any hastle with breakoffs or flying pieces needing to be prevented with extra blocking.
Tinker

 

[peter halle]

Another problem I see solved by using the parallel Guides is how easy it is to control the ultra thin pieces you are cutting.  I have been setting up backstops of sorts to capture those very thin strips from going airbourne.  Sometimes they break off at the tail end of cuts and so I make the strips longer than needed and then set up jigs for cutting to length if I am making angled corners.  It sometimes makes for quite a hastle.  You demo shows actually how easy it is to make even the thinnest slices without any hastle with breakoffs or flying pieces needing to be prevented with extra blocking.
Tinker

As a result of this thread I set mine up yesterday.  It was pretty cool to be able to cut 1 mm strips.  Repeatedly.

Peter

 

[Tinker]

Same here.  As a result of RD Muller's 3 excellent vids, I have finally decided to bite the bullet and make a call to "Uncle Bob".  I have been fooling around with some quite unbelievable setups for making thin strips thinking i could avoid it. RD has broken my resistance. ???
Tinker

 

[Wonderwino]

Another use for the parallel guides is to cut tapered strips with them.  I had to cut tapered returns for windows in an old building that was not plumb or square.  I just took a depth measure at each corner, cut the returns to rough length (+1cm), then tapered them to the depth measurement.  No better way or other set of tools that could do this with ease and accuracy.  [big grin]

 

[NuggyBuggy]

As a result of this thread I set mine up yesterday.  It was pretty cool to be able to cut 1 mm strips.  Repeatedly.

Peter,

Were you able to cut your 1mm strips after zeroing your guides and then setting the stops to 1mm directly on the scale ? Or did you have to use a compensating "fudge factor" like fshanno suggests ?

terry

 

[peter halle]

I ended up going thru the process of zeroing and checking and adjusting and zeroing again...

It doesn't take that long - I was just enjoying a mind clearing day - no rush.

As RDMuller said in the video, don't do these initial steps when you are rushed or under pressure.

Peter