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Post by sibejan on Apr 12, 2023 8:31:47 GMT -5
Hi,
What is your workflow when you want a dead straight cut while combining two guides?
Just ripped a sheet of 12mm birch ply (250x125cm) into 16 narrow long pieces (using a MT55 cc + Mafell F1600 and a Bosch FSN 1100) Now I noticed the cuts or not straight... (first time as far as I know). When all butted up there are no gaps, but when I turn one piece, there's a gap of 2.5mm with 10-12 pieces, with the other pieces it's less to zero. Exaggerated it looks a bit like this: (((((((( instead of |||||||||, and when turning one it looks like (((((()(
When combining, I always but the two rails, so that could be due to the unstraightness ('cause on this forum I just learned it might be better to leave a small gap in between). Unfortunately I already de-combined them, so I can't check it anymore with another F1100 if they were badly combined. Tried it with and without a gap and it seems the with the gap it's better. But when I check my combined guides, and clamp one completely, there is a little play (±1mm) possible when I firmly shift the other (with and without a gap in between the guides), but it seems to return to the original position. If I slightly move the coupled guides by hand and then fixate them, can the guides be mis-aligned?
And is it better to check guides with another long straight edge before cutting? (like I had to do with my former festool setup)
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Post by aas on Apr 12, 2023 13:04:17 GMT -5
You should leave a small gap when joining rails, but I never have - I just tighten nearest the join first - never needed to check with a straight edge.
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Post by sibejan on Apr 17, 2023 7:53:02 GMT -5
You should leave a small gap when joining rails, but I never have - I just tighten nearest the join first - never needed to check with a straight edge. I will for sure in the future. But is there nobody out there having had the same problem: not a perfect straight cut with 2 guides connected?
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Post by Knight Woodworks on Apr 17, 2023 10:53:12 GMT -5
I do butt rails together. It's been awhile since I've done full rips. Next time I do I'll have a look.
Could it be you got a bad sheet of 12mm birch? Recently I've had issues with offshore plywood moving after being ripped.
John
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Post by aas on Apr 17, 2023 12:39:27 GMT -5
Never had this problem, always cuts straight.
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Post by nanowire on May 12, 2023 3:04:35 GMT -5
When I combine two long rails I usually have a look along the edge and the slightest angle between the rails is easily visible. I find that although it is possible to connect them non-straight it takes both sloppiness and some bad luck on my part to do so.
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Post by newuser on Aug 16, 2023 22:47:47 GMT -5
Few months ago I was doing multiple cuts on 2.4m MDF then checking square with 600mm square.
Due to technique, clamp alignment, guide movement etc I found getting a ‘perfect’ square cut extremely hard and I do think the rails move very easily. Don’t have any other brand rails but heard others mention other types have a better grip. Just know that I have to pay very close attention to the saw movement as it is easy to introduce a slight nudge which will cause that deviation.
Combining rail cuts is the highest level of difficulty imo as the furthest rail will not want to perfectly follow your angle once it is connected, especially if you try and change the angle of a long run. Now I usually first set angle, hard clamp the first rail and then carefully connect the second rail while mid clamping the first to prevent any movement, then clamping the end of the connected rail.
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Post by aas on Aug 16, 2023 23:32:19 GMT -5
A couple of things to help stop rails moving...
First option - keep the non-slip beads clean. Try wiping off with alcohol, you will find the grip is hugely improved.
Second option - buy a roll of the Festool non-slip foam. There is a recess in the back of the Mafell rails that is the right size.
Joining rails is straight forward enough, tighten from the centre out. When clamping, loosely tighten one end, then position and tighten the opposite end, then come back and check and tighten the clamp for the first end. The rails don't move out of alignment once connected.
For crucial long cuts - especially mitred cuts where it is easier to introduce user error due to the saw being tilted over - add a middle of the rail clamped support. This needs to be the thickness of the rail or thinner (you can use a thicker board with just the end rebated to rail thickness). Once the rail is clamped, just touch the board up to the rail (no added pressure) then clamp on the far side of the board. Tis will stop you (the user) pushing the rail over and curving the cut.
For square cuts, invest in a decent rail square. I have an 800mm rail permanently connected to mine, if I need longer cross-cuts, I just add on rails. I use this set up doing cuts up to around 3.7m (about 12 foot) - the cuts are straight and square. In my opinion, a rail square is more important than to have than clamps.
Asides from a rail square, I also have the Mafell F-WA. I don't trust the angles marked on it to be 100% square out of habit, I set it to perfectly square with a Starrett square, checking fairly frequently. I have also used this to set angles for spiral staircase treads - a good addition to the setup if you don't have one.
Technique is key to everything. The saw, rails and a decent rail square work perfectly together. If results are variable the variation is coming from the user. In other words, if a cut is messed up - I messed the cut up.
Find a technique that works for you. You need to be pushing the saw down the rail without any lateral force, while at the same time holding the cable and hose out of the way. Try looping these around your arm, or even up your arm and around your neck if need be. Another option is to have your vac at the front of the cut behind the rail, so the hose and cable fall on the floor at the end of the cut.
Practise using the saw with either hand, some cuts will be easier with one hand over the other. In some awkward situations, you can also work from across the board so you plunge and pull the saw towards you - but please don't try this unless you are really comfortable with your skill level, and certainly don't do it on any board that might close on the cut, with or without riving knife, you have zero control over kickback.
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Post by newuser on Aug 16, 2023 23:39:47 GMT -5
Nice tips. I do use a benchdogs rail square but don’t always trust it depending on the situation. The cam locks can also score the aluminium and yet can slip without enough pressure. My favourite way to use guide rail is mounted by benchdogs, but that is often not possible + getting those holes accurate is a whole other topic.
Also a pity that mounting the rail square doesn’t also let you use a clamp on that side which I like to do with long cuts. I know other squares let you clamp like TSO?
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Post by aas on Aug 17, 2023 11:22:46 GMT -5
My rail square does allow me to use a clamp, but I've rarely used the two together.
I've never used bench dogs. I think the whole 'having a perfectly accurate table' doesn't interest me. Can you not fix the square from underneath with t-track adapters to stop it sliding?
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