Acceptable guide rail tolerance

[mouppe]

My 55" guide rail has a convex front edge which leads to a concave dip in cut wood at the worst point of about 0.005", or about 0.2mm. This is acceptable to me, although it is definitely noticeable. When I lay a straight edge on the cut edge the gap is clearly there, and I know it is due to the guide rail and not tension in the wood because it happens every time.

Does Festool have published tolerances for the guide rails as I have available for my straight edges and precision squares? I would be interested to know whether my guide rail is within the accepted tolerance limit, and what the tolerances would be for longer guide rails. I am looking to buy a longer rail but would be concerned if the edge is less straight than my current rail over its longer length. A number of my other Festools such as my OF1400 have micro adjustments down to 0.1mm which is less than the error I am seeing on my guide rail, so clearly we are in the realm of Festool's precision. By way of reference, this error is outside the tolerances of my straight edges, precision squares, hand planes etc.

Richard.

 

[greg mann]

Richard,

80/20 quotes their straightness tolerance at .0125" per foot of length. While I know they do much better, that still equates to .056" over 55 inches. That would be totally unacceptable in a guiderail but your .005" is only one tenth of the 80/20 standard. As an aside, how do you know just how good your straightedge is, and what is the stated tolerance for it?

When all is said and done, I think .005 is not much to worry about, and I would also expect a longer rail to not be any worse.

 

[jonny round boy]

I've noticed this with my 1400 rail. If I straight-edge 2 pieces of MDF and then put them edge-to-edge, there's a noticeable gap in the centre. I've not measured it, but at a guess I'd say it's maybe 0.25-0.5mm gap across a joint 1200 wide. Not too wide to close up when clamping. It's only ever been a problem once, and it was quickly & easily solved with a block plane.

I thought at the time I'd put a taught length of thin cotton along it & see what it was like, but I never got around to it.

I don't have any problem with my 800 rail, though.

 

[thender]

My 55" guide rail has a convex front edge which leads to a concave dip in cut wood at the worst point of about 0.005", or about 0.2mm. This is acceptable to me, although it is definitely noticeable. When I lay a straight edge on the cut edge the gap is clearly there, and I know it is due to the guide rail and not tension in the wood because it happens every time.

A 0.005" gap is only slightly larger than the thickness of one sheet of ordinary copy paper. 

Over a 55" rail that is extremely good. 

-TH

 

[mouppe]

Richard,

80/20 quotes their straightness tolerance at .0125" per foot of length. While I know they do much better, that still equates to .056" over 55 inches. That would be totally unacceptable in a guiderail but your .005" is only one tenth of the 80/20 standard. As an aside, how do you know just how good your straightedge is, and what is the stated tolerance for it?

When all is said and done, I think .005 is not much to worry about, and I would also expect a longer rail to not be any worse.

One of my 36" straight edges is flat to within 0.0015" and the other is 0.001". I checked my guiderail with both sides of the straight edges so I know the error is more with the guiderail. As I said in my original post, I am not concerned with the 55" but whether the gap will be significantly more with a longer guide rail. Also I was curious to know what the official Festool tolerances were.

 

[BobKovacs]

I've got to ask- are you guys building watches or space shuttles with these rails?  Those are about the only scenarios where I can imagine a 0.2mm variance being an issue.  This is woodworking we're talking about, right????

 

[Corwin]

I've got to ask- are you guys building watches or space shuttles with these rails?  Those are about the only scenarios where I can imagine a 0.2mm variance being an issue.  This is woodworking we're talking about, right????

Did you read the opening post?  

My 55" guide rail has a convex front edge which leads to a concave dip in cut wood at the worst point of about 0.005", or about 0.2mm. This is acceptable to me, although it is definitely noticeable. When I lay a straight edge on the cut edge the gap is clearly there, and I know it is due to the guide rail and not tension in the wood because it happens every time.

Does Festool have published tolerances for the guide rails as I have available for my straight edges and precision squares? I would be interested to know whether my guide rail is within the accepted tolerance limit, and what the tolerances would be for longer guide rails. I am looking to buy a longer rail but would be concerned if the edge is less straight than my current rail over its longer length. A number of my other Festools such as my OF1400 have micro adjustments down to 0.1mm which is less than the error I am seeing on my guide rail, so clearly we are in the realm of Festool's precision. By way of reference, this error is outside the tolerances of my straight edges, precision squares, hand planes etc.

Richard.

Seems reasonable to me for Richard to ask this question.

 

[BobKovacs]

Did you read the opening post?  

I did.  I was scratching my head on the while acceptable, it's still "noticeable" part.  "Noticeable" how- by using a high-powered laser straightedge and a micrometer to measure it?  I can't imagine a 0.2mm variation being "noticeable" in a woodworking project to 99.9% of the population- especially considering that seasonal movement of the wood could easily far exceed that amount.  Even with the longer rail mentioned in the original post, the same degree of variation would still be minute- especially over the longer length.  I'm just trying to understand the types of projects y'all are doing where this would even become a question in the first place.

 

[mouppe]

Did you read the opening post?  

I did.  I was scratching my head on the while acceptable, it's still "noticeable" part.  "Noticeable" how- by using a high-powered laser straightedge and a micrometer to measure it?  I can't imagine a 0.2mm variation being "noticeable" in a woodworking project to 99.9% of the population- especially considering that seasonal movement of the wood could easily far exceed that amount.  Even with the longer rail mentioned in the original post, the same degree of variation would still be minute- especially over the longer length.   I'm just trying to understand the types of projects y'all are doing where this would even become a question in the first place.

Bob,

It is noticeable by using the traditional methods of holding the edge up to the light against a straight edge. The same method that you use to check a hand plane for square. As I said, to me the gap is noticeable but acceptable and I wouldn't want it to be any larger on a longer rail. I was also trying to understand whether my edge is outside of Festool's tolerances.

When you set up your jointer, did you use a straight edge? Did you use a good square on the MFT setup or to make sure your table saw blade is perpendicular to the table? The error I am talking about is visible, and I presume you would have adjusted your setup to remove it. The problem with the guide rail being out is that milling the lumber is the first stage in any project. I know right from the outset that my wood is not straight and that error is compounded as I add shelves, doors,  joints etc. There is a micro-adjustment dial on several festools of 0.1mm. If it was not important to some people it wouldn't be there.

 

[grobin]

Certainly a less noticeable variant would be better but it will only bite if you are making wider boards out of narrow boards and that's what a joiner is for.

 

[counterfix]

i believe that the plate your showing is diffrant from the giude plate adapter as i've had this same issue i say this when i looked through the accesory kit  i think there was one thats recested so the bushing it self fits in it. there is a plate with a hole that can
hold a giude bushing but some of them have that blank space at the bottom of the bushing that causes slop.
i will be at the shop later today and take a pic of the plate or maybe someone has the of 2200 acc kit handy and can check

 

[Dixon Peer]

I would think it best in any event to take the work to the jointer before glue up.