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RAS cutting woes

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Bluekingfisher

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Ladies, Gents – I have just finished building my RAS table after having the saw sit for a year to the day in the workshop.

I’ve probably over engineered the table but I’m hoping I won’t have to build another one.

Anyway, I put a new 60T negative rake blade on the saw and after much fiddling and adjusting managed to get the blade square. Howerer, when I make the cut the blade seems to snatch as it exits the cut, no matter what I cut, solid timber or MDF, ply etc last 1/2” of the top of the board has a 3 or 4 degree off square cut. The bottom of the board and the cut off piece are perfectly square?? any ideas what may be causing this?

I have checked the saw over, everything else seems to be to in line and tight with no slop???

very frustrating.

Thanks

David
 

9fingers

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Have you got BOTH the arm and the blade square to the fence? If not then this culd be the cause of the snatch
RAS can be a real PITA to set up.

Bob
 

Bluekingfisher

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Hi Bob, your telling me, its a case of which part do you set up first?? I was having a think about it last night while lying in bed (as you do) When I pulled the carriage over slowly thinking this may help I noticed the timber was charred. I'm now guessing the carriage mat not be square even though I think the arm is square to the table.

I'll do a bit more research on it. The saw is an Elu 1251 (have they now been taken over by Dewalt?) anyway I have heard there is a forum on the RAS somewhere so I may track it down if I have no success on fixing it myself.

I'm hoping you are right and it's only adjustment issues rather than something more serious.

David
 

9fingers

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I set the arm up first but using a large square and picking a tooth tip and making sure that followed the square over the whole travel.

Then I set the blade square to the fence but I can't recall the method exactly. The order in which to do the adjustments does (should?) not make any difference.

I find the arm squareness needs checking every time I adjust the height.
Good luck

Bob
 

Bluekingfisher

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Thanks Bob, as with everything else, once I am more familiar with the machine I'm sure it will become second nature to set it up. Once I have a system for checking and adjusting the I'm sure the frustrations will lesson some.

I'll take some time out tonight, get into the WS, get my framing and machinists squares out and give it another go.

Hopefully I'll crack it, I hate having something not quite right before I move onto something else.

David








David
 

OPJ

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9fingers":1hsgvecy said:
Have you got BOTH the arm and the blade square to the fence? If not then this culd be the cause of the snatch
RAS can be a real PITA to set up.

Bob
I'll second that. I've never had to adjust a DeWalt/Elu saw like this but, on an old Wadkin I've used, yes, you can adjust both the arm and the head/blade in relation to your fence. So, the saw runs parallel to the arm but, if the blade isn't set parallel to this line, it'll most likely burn and snatch at some point.

Other than that, are you certain that your fence is perfectly straight and not slightly hollow in the centre, in the area surrounding the blade? That could otherwise explain the snatching, where both halves of the timber become 'free' at the end of the cut and, because the ends are not fully supported, the movement of the blade forces them back in to the concave edge of the fence.
 

Bluekingfisher

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Hi Olly - No I think I am quite happy with the fence, I did make a point of checking that as I had to run a straight edge along the fence of the RAS and my adjacent SMS to make sure all was in line.


The more feedback I get I am convinced the blade/carriage is not parallel with the arm. The good thing about this saw is that there are plenty of dials and gauges to reference against.

Thr RAS is a usefull tool but I can see why it's popularity has waned since the arrival of the newer and more simple to set up chop saws.

David
 

studders

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9fingers":jm07nv4y said:
Have you got BOTH the arm and the blade square to the fence...

Bob
And all levelled to the Table?
And at 90deg?
And...

:)

Have you checked the bearings in the arm for any slop?
 

Doug B

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I struggled setting up mine for a while until i realised the cup washers that hold the blade were not exactly parallel, a fine skimming at an engineers later & the blade runs sweet as a nut.


cheers.
 

Bluekingfisher

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Steve, thankfully it's as tight as a drum, no slop. It looks like the saw has been very well looked after, either that or not used much.

Doug, without using a micrometer I cannot tell if the cups are parallel or not. I have done the ye ball test on the spinning blade from the front , it look true to me, of course not something you want to get too close to. I have checked the bearings on the arbour, no slop there either.

I'll try for the simple options first by checking the alignments,if that doesn't solve it I'll have to investigate the mechanical aspects.
 

Bluekingfisher

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I hope not, it's a new neg rake blade, although that doesn't mean anything.

I'm still banking on it being alignment, a kindly samaritan has offered to send me a document on setting up a RAS with that I should hopefully solve my problem.

I have a couple of older blades too so I might try them, see if they have a similar end result.
 

kirkpoore1

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Bluekingfisher":1u4191j9 said:
... Howerer, when I make the cut the blade seems to snatch as it exits the cut, no matter what I cut, solid timber or MDF, ply etc last 1/2” of the top of the board has a 3 or 4 degree off square cut. The bottom of the board and the cut off piece are perfectly square?? any ideas what may be causing this?

I have checked the saw over, everything else seems to be to in line and tight with no slop???

very frustrating.

Thanks

David
David, I've read this several times trying to envision what's going on. Are you saying that the bottom edge of the board you are cutting comes out right, but the last 1/2" of the top edge is off? Here's what I'm envisioning:
rascut.jpg

Exaggerated, of course, and assuming the board is on the right and the offcut is on the left.

Does it matter how wide a board you're cross-cutting? Does it do it differently if, instead of holding with your right and cutting with your left, you hold with your left hand (the piece left of the blade) and cut with your right? Got any pictures of the result?

Anyway, since your fence is right, I think your best bet is to verify that the blade is cutting parallel to te arm. I still don't see why this would affect only part of the cut, unless the snatching is pulling the blade to the right on the exit. Maybe the arm pivot or the head pivot (vertical axis) aren't locked down all the way.

Kirk
 

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Bluekingfisher

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Gents, all - I would just like to thank everyone who offered help and advice on my troubles with my new, at least new to me RAS. I now have it all sorted out thanks in chief to the assistance of those on this forum.

For those interested in the cause of the problem, it was really a 4 fold issue, due mainly to my enthusiasm and neglect of reading in detail the operators manual. I have now had the opportunity to read and digest the workings of this rather intricate and often complex machine.

The faults were all down to misalignment of the blade across the relevant axis, i.e. perindicular to the table, square to the fence and in line with the carriage, which I have established is known as "heeling" Another of my faults was to use a framing square, this I found was not quite accurate enough when I doubled checked it all again with a carpenters bench square. I have the tolerances so close now it's not worth worrying about.

The other issue which I overlooked was the blade itself. It was a new 60T negative rake blade so I therefore naturally assumed it would be nothing to do with the blade. I was wrong, after getting the saw set up (with the framing square) I made a test cut, I still had the snipe at the end of the cut, that's when I used the more accurate bench square and found small varients. Again, I adjusted and made the cut, still the snipe at the end of the board. I was by now turning the air blue and pulling my hair out. I took the blade out of my SMS and fired it up...bingo, spot on.

I now have a machine ready for work but what a bear setting it up, too many levers, cams, springs, allen bolts and screws to work with. Now that I have it square I won't be doing anything other than making square cuts....life is too short.

Thanks again all, much appreciated.

David
 

9fingers

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David,

Do you know what the difference is between your two blades? presumably both have negative rake.

I too have both a mitre saw and a RAS and was considering getting rid of the mitre saw or more correctly not replacing it when it eventually dies (cheap Titan brand with bits breaking etc)
But I will keep the RAS set at 90 degrees and possibly with a dado head in for the same reasons that you cite and look for a replacement mitre saw when the time comes.

Bob
 

studders

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There's a little trick I learned for quickly making sure the Arm/Blade returns to spot on 90 deg.
Rout out a strip from the table and replace it with a sacrificial piece of hardwood. Once the saw is set up dead on 90 make a cross cut about 10mm deep into it. Now, if you move the arm to a different angle all you need to do is check that, when returned to 90, it follows the same cut.
Easies. :)
 

Bluekingfisher

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Morning Bob - The new blade inserted in the RAS is a negative rake blade, it has "For Mitre and RAS only" stamped on the blade. I bought it a year or two ago it's been in storage since then, perhaps it has warpped slightly?? although when I eye balled it while on the saw it showed no evidence of wobble.

I think I paid about £30 for it, so not a high end blade. The SMS is an Erbauer from Screwfix, I'm actually very pleased with it but the blade again is the one that came with the saw although gives a good enough cut for my wood butchery. When I'm ready to build finer things I will treat myself to a quality blade, CMT, Forrest or the like.

I only intend to rough cut with the RAS so only need somthing of average quality as long as the cut is straight. The RAS, when I bought it came with a CMT Dado stack fitted although only the two outer blades and a chipper, giving a 9mm cut. I'll use these for making finger joints on the TS.

I couldn't do without the SMS now, setting up angled cuts on the RAS would be a nightmare.

David
 

9fingers

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Thanks David,
I had not considered that the blade might be imperfect and wondered if it was to do with rake & clearance angles or perhaps chip limiters such as freud use a lot.

Bob
 

Bluekingfisher

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Studders - great tip. I actually have a a 40mm thick table top with a 9mm sacrificial MDF board screwed on top of that. When I replace it I'll make the scaricial top in three sections, the middle one being in line with the blades travel.

Thanks again.

David
 

Bluekingfisher

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Bob - I know you only get what you pay for, but the thought of paying £80-£100 for a blade makes me shiver, still, Christmas is coming, I may start dropping a few hints.

David
 
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