northwood sj270

[wrench]

we have been using this machine 10 months, (new) first month worked great with some issues, now we, along with northwood can't get saw to cut straight, replaced chain on servo to no avail. C axis or saw motor seems to be at fault. we do 20 kitchens/day, so repairing these miscuts or rerouting them to cnc is eating up our production time. we are getting software up grade soon they say, but no assurance that is answer. any one have similar problems? Or know what is fix? thanks wrench

[Dan R.]

Wrench, it is customary here to fill in your profile so that we all may know to whom we are speaking.

thanks.

[wrench]

I am maint. mech. for 20plus kitchen/day fab shop, it has not been smooth sailing by any means with this machine. cutting, calibrations, jetting/intensifier issues(KMT has been all over the repairs to their credit), Do we have a lemon or is this an issue with others?

[dustinbraudway]

Put your name in the sig line!

First of all Northwood is a first class operation. I have in all my years never heard of them leaving someone hanging. I am sure that Robby and his crew will figure it out and help you out.

[Nick]

What are the specific problems with the cut?

If the c axis is not set dead perpendicular, the blade will drag. Is the kerf wider and blade paint wearing unevenly? A out of whack C would not make cuts that have a bow in them I don't think, however play in it (is it antibacklash?) or the overall rigidity(or tightness of everything with stress on it) may cause the saw to "walk".

Try making like an 8" cut with the c axis at anything but 0, then move the saw away and spin the c, then execute the same cut again, if it goes back in kerf it just made, then the c should be fine. Or make the cut, then change the direction of the same cut so the saw spins 180* and see if it goes back into the same kerf. Stuff like that would prove the c axis is going where it should be I think.

[clhilde]

Cheap blades?

[Nick]

No way. You will see soon enough, all really good blades do is last longer and mask or make flaws in bridge saws by cutting better. You couldn't cut not straight if you tried on a CNC saw unless something was wrong. Still would like to know what specifically the cut problems are, that would help some to stab at it.

[Jqualey4130]

What are the specific problems with the cut?

If the c axis is not set dead perpendicular, the blade will drag. Is the kerf wider and blade paint wearing unevenly? A out of whack C would not make cuts that have a bow in them I don't think, however play in it (is it antibacklash?) or the overall rigidity(or tightness of everything with stress on it) may cause the saw to "walk".

Try making like an 8" cut with the c axis at anything but 0, then move the saw away and spin the c, then execute the same cut again, if it goes back in kerf it just made, then the c should be fine. Or make the cut, then change the direction of the same cut so the saw spins 180* and see if it goes back into the same kerf. Stuff like that would prove the c axis is going where it should be I think.

Or Use the pendant to put your C axis @0,0 and run a dial indicator across the blade(while moving in X w/ the pendant in jog) to see if it is out of alignment. If the Null offset of the C axis is off by more than a few thousanths, it wont cut that well.

[Nick]

If the C is not Aligned with the bridge, then the blade would drag and the cut would suck, but it would not be a curved cut or resemble a blade that walks I don't think.

Really, what Justin said to calibrate or confirm and make the saw cut the same line with the motor on one side first then then on the other side next cut and if it doesn't go in perfect it is the C.

BUT It sounds like it is not your C though since you got a new one and you mentioned a banana cut in the other forum, I don't think c being off would make a hooked cut unless it had play in it throughout the cut and the axis was "walking" from it.

[Miles]

What happened to wrench? Wrench did you find the problem? We have the same machine and have had it for about 4 months without problem. It's an awesome machine. We had the old version for 6 years and moved it to our other shop. We cut about 15 kitchens a day between the two shops, but we don't have a shop maintenance mechanic.

We have seen that when a blade loses tension and you push it hard, you can get some cuts that are barely out of square. About 1/32 from top to bottom. Bottom this is usually a blade problem caused by plunging too fast on hard materials.

Other than that, I agree with the others that it could be a C axis alignment problem. But I don't think it's a machine problem. Either a set up issue or a blade problem. Don't know why it would persist. Haven't seen this on our machine and haven't heard about it from others.

[Nick]

Miles, if that persists I would look further. Your cuts should be at 90 regardless the blade, and not sure about the blade losing torsion rational That is a ton. When I crashed my saw it was .3* out on the tilt axis and I didn't have that much of a variance.

Does it always do it to the side of the motor on an incline? I could see the pressure of hard cutting lifting that axis since the servo tilt is new for them more than a blade issue? I am lately of the opinion that "blades" take a lot of blame and a lot of credit for things that may or may not be the most dominating factor contributing. I think this is the case with a lot of manual older saws etc.

A blade flexing 1/32 of an inch across 1 1/4" is so unlikely to me at normal or heavy conditions, especially along the line of the least resistance. The saw should in theory have that blade "welded" in position, so that much flex from the bottom of the arbor clamp to the tip of the blade is a lot of blame for that steel to take unless you are rolling with suspect Chinese direct import blades. When I crashed my saw into the table, the blade was so almost not bent that I thought about continuing using it(it was violent) but it was only $170 for the blade so I tossed it, even cheap ones are pretty ridged.

[wrench]

Marty Roberts,Syracuse, NY
thanks guys for info, we do use zenesis II blades, our seam cuts are bananaed, and not 90,. requiring repair work by hand, we did extensive tests as you suggest to determine the cause, but our cuts after initial 4-5" are not square, out at bottom making seam fit impossible. Northwood has now informed us they will be in to upgrade chain drive to direct drive on servos, plus software. will keep you informed, thanks again

[Nick]

So it is the same cut problem Miles has, not an unstraight cut longways.... Why did they replace the c axis for that?

Northwood apparently thinks it is what I was thinking if they are re engineering the tilt axis. That should take care of it.

Miles, you need to get up on that upgrade!..........and then yell at whichever one of your guys tried to sound smart and feed you that blade torsion crap

[DavidL]

When this happens on our odler N'wood it is typically an issue with the c axis, 2x's now we have found it to be wearing within the bearing, when we see the cut not straight along the length of the cut, points to Chain.

[clhilde]

Chain???

You would think it would all be screw or gear drive. I haven't seen a chain drive since the older sawing system saws.l

[Ken Lago]

Northwood make bicycles on the side so they got a good deal on chains.

[wrench]

Marty Roberts/wrench
Stone Central,Syracuse,NY

Northwood is Sending direct drive components and upgraded software for saw and we will be down for two days next week as they install. If they knew of this problem as they apparently did why not upgrade before they sold and installed our machine? we also tried 4 step cutting (1/4" cuts) and got slightly better seams but still not perfect.They also recommended us to a blade manufacturer and buying a $600.00 blade which we did. What is that? thanks for all your info guys I really do appreciate your input and help on this, will keep you informed

[Nick]

What is that? BS . Blaming the blade and suggesting a $600 blade would highly irritate me, but I guess not as much as if that was really true and you could only use one specific blade without problems .

[Mark Lauzon]

On any saw, if you plunge cut into a seam, it will be problematic! (especially on exotic stone with hard and soft spots) I would oversize and use a seam phantom or mill on a CNC if you are truly looking for perfect seams. It is tricky to program and layout a cut batch that does not plunge into the seam. (say goodbye to tight nests if you try to avoid plunges) In my last shop we oversized all seams and milled on the CNC. I am pretty sure that would be considered a "best practice" in most high end shops.

Nick, That blade he is talking about (if it the one I am thinking of) is one Barry Brandt worked on....it is not a normal sawblade as we know it, It's designed to perform on miter cuts and be re-tipped...you are really paying for the core. If you are really curios, just give Barry a ring....I promised not to talk about it till it comes to market. (It has been a few months) I have never actually seen one....for what it's worth...the idea sounded cool.

[Nick]

On any saw, if you plunge cut into a seam, it will be problematic! (especially on exotic stone with hard and soft spots)

I dont follow why Mark?

I plunge cut and pull the blade out of almost all our seams and you couldn't tell the ends from the middle. Just put together four 57" long seams in a slab shower in arabascato all sawcut like that and they are all perfect...well minus a little slab warpage .

If a saw has a blade at a perfect 90, goes down dead straight, goes forward dead parallel and comes up dead straight, regardless of the material it will be a straight and perfect line everytime. If it is not, the reason is in the machine setup/build, but not the blade. I can tell you from flat polishing marble that the ends of the cuts do not even have a different diamond wear to them and look the same as the middle of the cut. On our old saw that was not the case as there was a little different markings from the diamonds where it went in and out so I think that it is true with a lot of saws plunge cutting a seam could be a problem, but a CNC saw or perfectly installed manual saw it should not be.

Being on my third bridgesaw, each progressively nicer, it is obvious how blades went from being a big deal to a non factor in order of that progression, that includes "flexing" with miter cuts. I am mitering 3x faster with my current saw than old saw with the same blades and funny how the blades on my old saw would "flex" a little on miters but somehow at much faster speeds do not on the CNC saw. If a blade has no where to go becuase the force pushing on it is not greater than what is holding it there, then it goes perfect, if that force is enough to work whatever play in the machine, no matter how small, it will.

[Ken Lago]

Nick, just wait till your chain gets worn a little

[Nick]

It should be already from everyone in my life jerking it

[Mark Lauzon]

If if if....but if, in reality....You want a perfect seam every time? Mill it or dress it. I can imagine that the right saw, with the right blade, properly dressed, and under the right conditions you could get a seam that might rival something coming off a CNC machine....I see a lot of really crappy seams that were cut on saws....most as a matter of fact, not so much so with seams that were milled.

And in the case of Wrench....he is using a SawJet which combines water jet and saw cuts! Never gonna get a perfect seam that way....dress or mill.

At Venetian, they been doing miters on the CNC. That is proving to be an amazing way to get perfect miters. I almost think if I wanted to make perfect miters and it really mattered I would probably miter on a saw and then re-mill the parts on a CNC. When you mill on a CNC the polished side is down and you don't deal with big soft curves that result from the variation of thickness in the material. It matters for them since they do not install the parts. They are being shipped to big commercial jobs and the finished size has to be exact. It works amazingly well. (slow as hell tho since the parts are not being cut with a miter, 2008 sawjet does not do that trick)

[Nick]

Why would a jet share the line of a seam? I am not saying that my saw seams are better than seam phantom(although I have thought about cutting them at 89.7* ) but they are quite similar to milling them on the CNC, and if I did cut them at a .3* angle they actually might be better. All this blade dressing and blade type and blade core is all important, but a huge scapegoat for other issues. Just saying, it is amazing how the same blades on 2 different saws can yeild different results. How perfect is your blade with the bridge? Think that every 2 or 3 thousandths doesn't make for a more chipped cut? Stuff like that I think is what really matters. I do understand the perfect world/reality stuff, but if you are setting up a machine with dial indicators, machinist levels and all that crap reality can be very good, and should be expected for a real 5 axis CNC machine.

Mitering on the Router is the worst for so many reasons, mainly time, kerf, and still don't understand how to miter 1 1/2" of something fragile that way safely. I understand the accuracy for spec work, but a CNC saw with probes is beyond within reason for that kind of stuff. Mitering on the CNC is totally legit if you don't have a saw to do it or do it well, but if you miter a lot, then it would be a problem and you would need a saw.

[Mark Lauzon]

Mitering on a CNC works perfectly and chip free, it does not produce curved miters....you don't have to stop cut the miter and separate the parts with a grinder and then hand miter or double cut the part...A low dollar per hour worker can run the sawjet & CNC router, producing great product without years of experience and weird science.

I am posting a few pics that I took with my phone the last month I was consulting in the shop in Seattle so you can appreciate what I am referring to.