parallel issues

[hitandruntz]

I'm new to festool but not to carpentry. I used to be an independent trim contractor building and installing all my own product. Now I'm a union millworker working with ultra high end outfits as an installer. I got my first festools in January and put them right to work. overall I'm very happy with them and the very generous Festool community here on FOG. to get my feet wet with the tools I chose a couple of projects that would allow me to use the full arsenal of the festools Ive acquired.

First project I built were 2 home made sysports out of melamine. nothing complicated. I was very careful during the ripping process.I would rip  a quarter off one length of the sheet as a starting point, then measuring both sides then clamping and then checking again and then ripping. I repeated this process 3 times. after my rips I measured the ends of the boards and they were on the $. at this point I'm really happy and everything is pretty straight forward as it should be. next I routed a 1/4" dado referencing off the back edge with the edge guide and I'm really enjoying working with the festools. I pulled out the Lr32 and bored all the holes for the drawer slides. I went 37 mm from front edge then I measured the last hole on the actual drawer slide for the euro screw and laid it out on the box and bored those holes as well. next I used the domino for all the joinery. there was a little learning curve but nothing out of the ordinary.

Now I go to assemble and this is where I start to see issues. there were no issues with the routing, dominoing or Lr32. the problem is that the widths of my cabinet components  were different. one top was 5/32 big. at this point I thinking oops, my bad I must have a bad process. but I did check the measurement after each cut at either end of the 8' rips  and they checked out and I was satisfied. so I have a mystery on my hands. I made the adjustments and redodoed the top and went on with the project. I finished the build and am overall very happy with the results.
BTW, I calibrated the green adjustment knobs so there is no slop from saw to rail.

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I spent a bunch of time on FOG reviewing the posts about parallel ripping and different peoples processes. In between the two builds I received the parallel rip guides that use the t-track. and also I built a rack to store the guide rails on my garage door and my wife came home and opened the door and they fell out and hit the ground. my fault and I reworked the design so that cant happen again. there was no visible damage but I don't have a 9' straight edge to check it.

so now I go to start my second build which is a dresser for my daughter. its 3 cabinets with inset drawers and a door that get screwed together and is on wheels. she is gonna be going to college soon and I wanted it to be easy to move.

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my process is different this time because I have 3 sheets prefinished birch plywood stacked and clamped together. also I'm using the parallel rip guides. so I start by ripping 1/4" off of one edge. now I set the parallel guides very carefully and clamp the rail to the work piece(i do this every time).so this time I measure at both ends and the number is the same. now I check the center and I'm 3mm larger in the center. now I'm like  ???. after I cleaned up the first edge I had to rotate the guide rail 180 degrees to reference off the freshly ripped edge to use the parallel rip guides. what I'm thinking is that I don't have a straight rail. I think its out by 1.5mm. so when I rotate it 180 degrees its out by 3mm. so anyways I unclamped the rail and lifted the rail off the board to look at it and then reset it only to get the same 3mm discrepancy. I have a home made mft style table for ripping and its not perfectly flat. its crowned up in the center by 1/8. I'm thinking this isn't going to make a difference unless I'm ripping on a bevel but am not sure.  so i made the rip and the next rip (with no rotation of the guide rail) was the same width at both ends and the middle. now both sides of the rip is crowned the same way.

on with the build. routed the1/4" dado referencing off the back edge for the cab back, Lr32 54mm off front edge for the inset detail, domino joinery. all went on without a hitch. now for the assembly and the widths don't match up. I had to re cut and re dado 2 tops and got it to work.

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I have built hundreds of cabinets with traditional methods and have never had componentry widths not match up by this much. that's my only complaint and I'm not blaming festool for my issues. I'm wondering if someone else has had the same issue as me and what you did to change your process to get more accurate results.

on the upside I am extremely happy with how the tools performed in on every other level. faster.easier.smarter. is no joke. glue ready joints after every cut is a major timesaver. splinter free cuts on both sides of blade just blows me away,not only saving time and steps, but material too. crosscutting plywood has always been an issue and pretty much a total nightmare with a table saw. After full days of sawing, routing, dominoing, and sanding I had no dust on me and at the end of the day a small amount on the floor. I'm used to being covered head to toe in dust. building with the domino is such a superior way to build stuff. its so much stronger and quicker. before I was screwing everything together. personally I prefer to build fastnerless. or at least the appearance of fastnerless. it may seem a little slower but it finishes faster with out having to putty or do extra finishing to hide nail holes or screws. being able to use the router with the guide rails and the centerline on all 4 sides of the router makes it a breeze to use and am able to perform complex routes with ease compared to traditional methods. normally I would have to make a jig for everything for the router now I don't and I love it. it gives me so much confidence in the process. the Lr 32 is amazing and Ive honestly never been happier or had more confident in that aspect of cabinetmaking . just by adhering to a few simple rules of the 32mm system all the math on drawer box sizes ,door and drawer front sizes are all done for you. all you have to do is make your panels on an increment of 32mm and all the prefigured out math works like a charm(if you don't know about it check out this link)    http://www.cabsystems.com/KISSII/KIIrivDe-mail.pdf
you don't need any fancy gigs for installing drawer slides or hinges if you lay out the holy rail at the right dimensions from front edge and from the back edge. all you have to do is use euro screws and screw your hardware into your pre drilled holes. 

so basically I'm thrilled to be using these tool and have a renewed energy and excitement for woodworking but I need help to trouble shoot my parallel ripping method or not maybe its my table(i doubt it but maybe) maybe I need a new guide(i think so but maybe not). my confidence level has skyrocketed in other areas except in this area (all time low for parallel ripping) this is really the only thing I need dialed in and any help would be greatly appreciated.

My next strategy is to clean one edge and cut my next piece slightly oversized and then cut to actual size. I found a post about rips being concave and apparently humidity changes and stuff stressing out the sheet goods. I have to build one more sysport and will go  through the whole process again probably this weekend.

Thanks in advance, John

 

[tjbnwi]

Check the rail with a tight string along the edge. If it is straight, the camber in your table is causing the problem. A flat work surface is a must.

Tom

 

[dsweetser]

I cannot tell from your post if you are joining to rails together or using one long rail. If two together, before you tighten the connectors slid the saw over the joint to ensure they are straight.

 

[hitandruntz]

thanks for the replies. I am using the 2700 rail. so I am not connecting two rails together. I have a 7 ft long table and it has a slight crown to it. I centered a 6 ft level on it and i had to shim up either end 1/16 and the level was touching in the center. as far as a string line goes I'm going to have to wait for some one to be around to give me a hand or ill have to rig something up. I have an idea that ill try tomorrow with the string line. as far as having a totally flat surface goes is it really a must. mines pretty close. how did you build your rip table? and how flat is it? I would have no problem reworking my table if that was the problem.

thanks  -John

 

[tjbnwi]

No need for someone else to pull the string tight. Spring clamp the string to the flat area of the rail, pull it around the clamp boss at its mid elevation to the other end. Do it on your table with the ends shimmed level, then with the ends on the table.

My table is a torsion box, it is dead flat over 8'. Think about how flat the top is on your table saw.

Tom

 

[Nick C]

I think your rail is curved. I would deal with that before worrying about the table. One way to check. Drive a couple of finishing nails part way into a sheet of plywood, separated by a little less than the length of the rail. Position the rail so it contacts the nails, and draw a line along the edge. Next, flip the rail around and do the same thing from the other side. Now, at the nail locations the two lines are separated by the thickness of the nails. Measure the distance between the lines at the midpoint, and you should also get the nail thickness. If not, the difference is twice the straightedge error. I think 1.5mm is too much of a discrepancy if your workflow involves flipping the rail around which, as you observed, doubles the error, and gives you a panel with an "hourglass" shape. If you modify your workflow so that the rail does not get flipped around, you would at least have parallel edges, although with a slight curve. For your systainer cab, which has no fronts, this would not be an issue. Drawers would be a little bit on an issue, and inset doors could be more of a problem. Word of warning: These rails, especially the long ones, require careful handling and storage to keep them true. The aluminum allows a fair amount of flex. Which brings me to my own personal jury rig: I have an older rail that's a little banged up, and has some curve to it. I do the same thing you did, except I use a third clamp and a wood scrap to nudge the middle of the rail back where it belongs. Don't need much force either. Good luck, and enjoy your Festool arsenal.

 

[hitandruntz]

thanks for the advice. I will look further into this tomorrow.

 

[Kevin Stricker]

Couple thoughts:
  Being a long time table saw user you have probably developed the habit of pushing your workpiece towards a fence as you make a rip.  Make sure you are not pushing sideways on your TS55 as you make a cut as you will get crooked cuts.  Second, make a rip and remove the saw and push the boards back together, hopefully they come together tight.  Third when you clamp both sides of a cut make sure you are not over clamping.  Clamp your rail then look at the center of the rail and make sure it has not lifted off the plywood.  It's can be a problem if you are clamping the rail to your table over the top of a piece of foam as the foam will compress at the sides.  You do not need much clamping force to keep your rail in place.

I hope you didn't end up with a crooked rail from the garage door incident, I thought of mounting mine there then had a vivid visualization of it hitting the concrete.  If you do have a crooked rail you should be able to compensate some by always referencing your domino off the front edge of your cabinets and leaving the back(rest) with a sloppy fit.  You may also be able to compensate some with your cutting technique.

Good luck.

 

[hitandruntz]

I'm going to check to see if the rail is bent but i am still very open to the idea that its me pushing the saw and the rail moving because of my technique. everything I've ripped so far has been very slick material. and I'm pretty sure I have been over clamping as well. I've  been tightening them pretty tight.so i will change that up as well. come to think of it the very first cuts i made were ripping 4x8 sheet of pre finished birch for my ripping/assembly table. the table I built is a torsion box with a mdf mft style top that i patterned off using my mft3 top and a top bearing 1/2" bit and some rail dogs . the torsion top has a crown to it. I didn't check it when I built it because I didn't think it was necessary, but now it kind of makes sense that it is crowned cause everything else i built is crowned as well. I'm gonna investigate the torsion box today too and measure all the widths of the individual members.

thanks for the help    -John

 

[hitandruntz]

OK, I just checked the rail with a string line and then I did the pencil line with and with out the nails and rotated the rail 180 degrees. i did the string test first but as a visual it was hard to see how much it was off but it was off the rail a just ever so slightly.so I did the pencil test with the nails and I could see it was off a tiny bit and tried to measure and it appeared to be right around +-1/64. next I did the pencil test with out the nail and I did it twice and the rail is off by a .5 pencil line. there was no gap in the pencil lines in the center of the rail the pencil line just got thicker. so at this point  I think its me pushing the saw laterally because a .5 pencil line x 2 doesn't add up to being off by 5/32. so the next build I will be extremely careful with my technique. I was being very careful with my measurements on the last builds but honestly I wasn't paying attention to lateral pressure on the saw. and again the material I used was extremely slippery.

 

[nanook]

it may be that the rail is slipping - but I doubt that a little bit.   My experience has been that the rails grip very well on their own, also I'd expect the far corner to be out if your pushing the saw sideways (maybe not 100% though if your clamping both ends - then you would see mid-rail deflection)

I wonder if clamping aggressively is not making the boards conform to the warp in the table prior to the cut and turning the straight cut into a curved cut when the boards are released?  
In terms of clamping - I really like the rapid-clamp for attaching the rail to the work surface.   Great for holding the rail in place & unlike the Festool F clamps it doesn't suck the rail right down to the board or underlying table
What about seeing if the problems persist when working on the garage floor slab? Just use some spacers or cardboard to keep the teeth off the concrete.    

 

[hitandruntz]

I am glad to report back that I just made a series of parallel cuts that were perfect. so it was totally user error. on these rips I lightly clamped the rail to the workpiece and lightly guided the saw down the rail. the parallel cuts I made were cut using 8' scraps from 8" to 12"wide that were left over from previous projects. the reason I  mention that is because  ripping out of full sheets may release certain stress due to humidity or whatever and possibly not have a straight cut. so on future projects I'm going to continue to monitor the rips I make out of full sheets to see if that was part of my problem. and also when I stack sheets to rip my parts I will handle it a little differently as well because looking back that may have something to do with my discrepancies. thanks again.

 

[Nick C]

This is an ongoing cause for concern, and has been the subject of other threads. Without that initial straight cut as a reference, it's hard to make a parallel cut or an accurate crosscut, not to mention dadoes, rows of holes, domino registration marks, etc. There are a few things going on here. The long rails are not terribly resistant to lateral forces. If the rail is true, and lateral force is applied when cutting (or routing), the rail will deflect a small amount, with the greatest deflection occurring at the midpoint. The solution is obvious: Don't apply any lateral force--it isn't necessary. There is another related issue, however. The rail must be stored and handled so as to minimize any lateral forces that would cause it to deflect, because it might take a set and become curved. The shorter rails are easy to hang vertically, but this is not practical for the long rails--which of course are the ones that are most sensitive. A possible solution can be borrowed from our machinist colleagues, who often store their long (and very expensive) straightedges on hooks or pegs that are "qualified"--i.e., they lie in a (very) straight line. A final issue is workflow-related. We frequently need to rotate the rail 180deg to make a cut parallel to our reference edge, especially when using the parallel guides. So any errors in straightness are doubled.

My newest, most convenient, and (of course) expensive solution is to connect a pair of the 55" (1400mm) rails for 8' rips. Like many, I got one with my saw. I bought another one with the holes. When I connect the rails, I confirm the straightness at the connection point with an alignment tool, called a Straight Align, that's made specifically for this purpose. This eliminates any misalignment right at the midpoint of the cut. The tool is quick--after I clamp the rails, I double check. Every time. This adds just a few seconds to the setup, but it allows me to rip with confidence, even when flipping the rail, and I don't have to deal with long, unwieldy rails. The Straight Align is about $100. It's made by Betterley Industries in Blaine, MN. Contact is 800-871-7516, or email@betterleytools.com. They also make a very nice setup gage system, called the UniGage, which is worth checking out.

 

[greg mann]

It is good to be getting some clarity here, and even though there was a report in the other thread that 1.5mm bow is within Festool's specification, I think it is important to evaluate workflow. When it is reasonably practical the easiest way to avoid thes issues is to work with shorter stock before the longest straight cuts are made. Why fret over an 8' cut if the stock will wind up at 4', or even 2'?

That said, I think 1.5mm over 8 or 10 feet is problematic. One poster indicated they took most of the error out of their rail with a little gentle persuasion. You can argue that it should not be necessary but what is your argument if you damage a rail that had been perfect? I think hearing more about the tweaking process would be really useful for those of us who wind up in the unenviable position of having a rail that needs tweaking and can't work around it, whether it came that way in the first place or we made it that way by accident.

 

[hitandruntz]

just to clarify, I didn't have to tweak the rail at all. when I did the pencil test the pencil mark at center of the rail was off by 1/2 of a .5 pencil line which I can definitely work with. Once I saw that I grabbed some scrap 8' pieces and cleaned up one edge then rotated the rail 180 degrees and lightly clamped and made sure there was no lateral pressure when I operated the saw. and the rips were perfectly parallel. which is a huge relief to me. I'm glad I got to the bottom of it and with the proper care taken I can definitely achieve parallel cuts with the equipment I have. so my issues were most likely an accumulation of errors that made my rip widths inconsistent. If I were to find that my rail was bent then I was going to cut it in half  and join the two together and start the investigation all over. If I was willing to accept 1.5mm discrepancies  in 8'  I wouldn't have invested all this money in festool. I could get those results with a wood straight edge and a skil saw. But I have made the commitment to change my tools over to the festool system and I trust that the system works. trust is a huge deal for me when it comes to tools. If I cant trust them I might as well get rid of them and get something that I do trust.  when my first build had issues i didn't panic and I changed up my process a little bit and watched things a little closer but when my second build had the same issues it was time to ask for help. and I'm glad I did.

I'm not sure I want to change the order I process material though. Ive always ripped then crosscut. It has saved me  a lot time generally making the least amount of  cuts. I would rather exhaust every effort to fix my issues than change my routine. if  I couldn't fix my problem then I guess I would have to change the workflow.

one thing that's going to be hard for me to change is going to be not putting the extra pressure on the saw. When I started framing I used a skil saw and I held on to it like my life depended on it. so if it jumped it wouldn't jump back onto me or out of my hand. actually I hold every power tool like that with the death grip. so it feels very foreign to me to not put extra pressure on on a tool. so there is definitely some learning curve and that's what I'm going through.

 

[Kevin Stricker]

I'm glad you got to the bottom of your problem, my recommendations were based on my own experiences making thousands of cuts and plenty of mistakes.  Festool may be "Smarter" but there is still a learning curve, how many other tool companies need ongoing "end user training" after all?

There is no reason to change your process, you have it right.  Also the idea that two joined rails is better than a long one is what the guy without a 3000 rail says.  We are generally the source of error in our woodworking(speaking from experience here) the fewer cuts and measurements the better chance we have of having things work out.  Why crosscut then make several similar rips each with the potential to introduce human error.  This process only makes sense if you are cross cutting, then taking your pieces to the table saw to make your rips.

One other thing, when working with prefinished ply and melamine slow your cut rate WAY down.  Slow cuts make much more of a difference in cut quality than any other variable( blade, plunge depth, etc.). This also helps give you a straighter cut, think about walking the dog.  Your goal is to use the least amount of force on the saw, just plunge and walk, making sure hoses and cords are not a problem.  Save the speed rips for sheathing and subfloor.

 

[hitandruntz]

thanks Kevin, I'm very relieved that it was user error. thanks for the tip about slowing down the rate of cut as I was not aware of this. I want the highest quality cut I can get so  I will keep this in mind in the future. rushing through the steps doesn't save any time if your cuts are inaccurate and have to do extra steps to fix whatever errors you have made.