What am I doing wrong? planer/thicknesser? Crates a bow :(

[sitefive]

Recently bought a metabo hc260 planer , but I'm having a trouble trying to square up the material if it's longer than 1metre.
It always creates a bow in the middle of the wood to the inside on both sides, I realize the beds aren't really long of the planer but I try to hold really tight so it doesnt moves at all but still it creates a bow in the middle like this:

What can I possibly do to get normal results and without the damn bow?
Thanks.

 

[Billy Flitch]

Hi, often this happens when the blades have been replaced in the machine and they are not correctly alined. If you have the instructions for the machine study the section that deals with the replacement of blades. HTH.

 

[OM99]

From previous post on here it sounds like you have tightened your cutter blade too much.

but someone with more experience can provide more info though.

Oli

 

[sitefive]

the machine is new, haven't touched the cutter blades at all to be honest. Could they be set incorectly straight from the factory?
Btw does this have anything to do because of the beds are too short? I did passed through it yesterday just 1.20m ''long'' beams and i was positive they didnt moved at all when I passed them through.

 

[OM99]

most likely you blades are set wrong from factory. get a straight edge against the blades to check them. even if just one of them is overtightened it will cause a bow to be created.

Length of the beds would not cause a bow.

 

[blackrodd]

More information needed, as in timber size that you are trying to straighten.
If it's 20-25mm thick, you need a lighter touch or the timber stock will just get planed as you will just follow the existing shape.
Have you checked the setting of the cutters? First, UNPLUG the planer,If you don't have a supplied setting jig and handbook, Level the two beds and do Just a quick check with a straight piece of timber that the timber carries about 2, or 3mm when the cutters are rotated,using pencil lines on the bed ends to check.
Do this on the left, centre and right on both cutters, if not, that's likely the problem
You should always follow the hollow side down principle, on flat side and edge, after loads of experience, I can straighten the "round" side as no doubt can many others on here.
For a good answer some pics would be very helpful in you're explanation and for the advise to be to the point.
Regards Rodders

ps, does any member live nearby?

 

[sitefive]

how exactly you would check with the straightedge?
says in the manual:
-place straightedge over outfeed table and cutterblock
-turn cutterblock by hand one turn against the direction of feed
-the planer knives are set correctly if the straight edge is moved forward 4-6mm by the turning cutterblock

Did that and it's turning by about that 6mm in all places, and the blades seems set very evenly to me.

The timber is plenty massive , 20cm x 5cm so can't really bend it by hand.

 

[blackrodd]

how exactly you would check with the straightedge?
says in the manual:
-place straightedge over outfeed table and cutterblock
-turn cutterblock by hand one turn against the direction of feed
-the planer knives are set correctly if the straight edge is moved forward 4-6mm by the turning cutterblock

Did that and it's turning by about that 6mm in all places, and the blades seems set very evenly to me.

If that's the case, (Above), some pics of the timber you are using will be helpful, and see where the problems may be that you have experienced.
Its probably down to needing some straightening and planing time to hone the skills needed.
8x2, in old money should be a doddle to straighten, are you using the cupped, hollow side down?
Regards Rodders

 

[RobinBHM]

Just to clarify, is this across the width of the board or down the length?

 

[sitefive]

btw when checking with the straight edge, should you Place the straight edge only on the outfeed table so its paralel with the outfeed table+a bit over cutterblock and try to turn than to see if it moves those few mm, or you should place the straightedge on both infeed/outfeed table so it really isn't paralel to anything. when placing the straight edge over the both infeed/outfeed table the cutterblock moved the straightedge by the few mm it needed, but when you placed the straightedge only paralel to the outfeed table+ cutterblock it didn't moved it at all!
not sure which is the correct way?

 

[blackrodd]

As in my first post, level both beds, infeed and outfeed both parallell, and check with a timber straight edge, as you're book said 5-6mm,
Mine I do at 2-3mm.
Rodders

 

[Andy RV]

It sounds like your knives are level to the tables, the amount it drags your straight edge will depend on the height of the tables. The outfeed table should be set very slightly, and I do mean very slightly, below the knife, it only just catches your straight edge. The infeed table is set to the depth of cut which you desire.

It sounds to me like your tables are not aligned. i.e. flat to each other. I'd say they are probably tapering up towards the middle.

You can check your table alignment with a long straight edge and feeler blades. I'm not familiar with the machine so I do not know if any adjustment is available, if it not you'll have to shim to correct the error.

 

[Andy RV]

Or perhaps your outfeed table is too low?.......

 

[sitefive]

well just re-set the knives so they are at the proper height as stated in manual, seems like they weren't set right from factory :twisted: re-tightened the screws so they aren't very tight , but the problem is still here!
I do not believe that this is fault with the material I'm planing as I have had tried with at least 30different thickness/length boards and it crates the bow for all of them.

It's not a large bow, maybe a 2mm bow over 1.5metre length but you can't join 2 pieces together if there is a damn hole in the middle of them!

Also there is no height adjustment for the outfeed table, only for the infeed table.

 

[wallace]

I had this problem when I first got a planer, and I was told I was creating a sprung joint which is good if your joining boards. But not good if you want a straight edge. Maybe its your technique?

 

[custard]

well just re-set the knives so they are at the proper height as stated in manual, seems like they weren't set right from factory :twisted: re-tightened the screws so they aren't very tight , but the problem is still here!
I do not believe that this is fault with the material I'm planing as I have had tried with at least 30different thickness/length boards and it crates the bow for all of them.

It's not a large bow, maybe a 2mm bow over 1.5metre length but you can't join 2 pieces together if there is a damn hole in the middle of them!

Also there is no height adjustment for the outfeed table, only for the infeed table.

You're a difficult man to advise.

You performed the straight edge test and said everything worked according to the specifications, which suggests the knives were correctly set.

-the planer knives are set correctly if the straight edge is moved forward 4-6mm by the turning cutterblock

Did that and it's turning by about that 6mm in all places, and the blades seems set very evenly to me.

Then you ignore those results and decide to re-set the knives yourself, and now conclude the knives weren't originally set right after all.

That was probably a mistake. You're not very experienced and setting knives isn't the easiest job in the world, so I wouldn't be at all confident that you've improved matters. However, what's done is done. You should now double check all your knife settings, then do some more research, sleep on it, and re-check them all again! Only after going through a long, patient process like that can you begin to be reasonably confident that the knives are indeed correctly set.

Then you should start where you should have begun in the first place, by examining your technique. You might think that planing on a machine is simple and doesn't need much thought. But it does, you need to follow a careful and consistent routine. The hollow in the centre could easily have been caused by taking too deep a cut and failing to keep sufficient downward pressure reasonably close to the cutter block at the beginning and end of the cut. Or by pressing down too hard on a bowed board. A useful trick during set up is to scribble all over a board with pencil to see where you're actually cutting away material. You only have a fairly short period of time to get this sorted, because before long the knives will start to lose their sharp edge, which will change the characteristics of the planer completely and make set up more difficult. So if things aren't going well don't keep banging more timber across in the hope it will all magically sort itself out. Stop, think, and plan your next step.

Once you're absolutely confident that those two stages have been carefully followed then, and only then, is it time to start considering table alignment. But under no circumstances should you start messing with that until you are 100% positive that your technique is correct and the knives are correctly set, otherwise you'll just get yourself into a complete mess.

 

[sitefive]

wise words well at first I had no idea how to check the blades,and was checking them in the incorrect way ,however after even more research and couple of Youtube videos I could safely say that they were infact not set properly, Setting them and aligning was total nightmare,however after half an hour fiddling they seemed perfect and what they should have been in first place.
It actually improved the Finish after setting the blades ,which I now think are correct, became much more smoother ,before that they were doing only half-decent job and the finish in no way resembled a finish you can get from a planer.

I do take only 1mm at time to not waste too much timber, However now I suspect that there is something wrong with the outfeed table and its sagging a little bit towards the centre where the cutter blade is.however there is no adjustment whatsover for that

 

[sitefive]

well Just wanted to go do some shims under the outfeed table--- but than I just saw these little black grub screws which I think adjusts the angle of the outfeed table by a tiny tiny little bits which I suspected could be wrong.

if anyone have this machine or one of its clones maybe can tell what they are for? they do seem to adjust the table angle by a little bit but maybe they are not for that purpose?
If the blades weren't set fully correct from the factory than maybe the table also is a bit off from factory.

 

[custard]

I do take only 1mm at time to not waste too much timber, However now I suspect that there is something wrong with the outfeed table and its sagging a little bit towards the centre where the cutter blade is.however there is no adjustment whatsover for that

Couple of points.

Actually a 1mm planing cut is quite heavy, once the knives have dulled down a bit you'd actually find it fairly difficult to keep a reasonably hard piece of timber flat on the table with a 1mm planing cut (a 1mm thicknesing cut is a different story). Aim for 0.5mm planing cuts until you've had more practise (remember, that's still about ten times thicker than an average hand plane cut).

I'm still not convinced the time has arrived for playing with the table settings, do you have access to a really good quality spirit level or a straight edge with which to check table alignment? It's far better to be able to check the alignment rather than just make blind adjustments in the hope you'll get it right.

But if you're determined to have a go then ask yourself how you could keep a written record of all your adjustments and reverse them if necessary? Don't lock yourself into the conclusion that the outfeed table is dipping towards the cutter block, maybe it's the infeed table, maybe it's dipping away from the cutter block, maybe it's dipping only on one side? You need to plan a series of tests, making small adjustments (don't forget shims are easily removed to put yourself back to the original settings) and then checking the results on timber at each stage. Write it all down then think about what these experiments are telling you.

 

[blackrodd]

Don't forget to tighten those screws!
By using the wooden straight edge, (400mm will do) and setting the cutters to "carry" the timber 2-3mm (4-6mm, in your're handbook, you say) , and with the beds parallel to each other, that will give you the correct clearances for the cutter block and out feed table set up to work correctly.
Go on the HSE site and soak up everything said on there and hopefully avoid any accidents, Is Peter Sefton near you for some training?
You just need the technique and good safety practices to follow on for you to be in planer heaven.


If I have timber with a 2mm bow, then I set the infeed bed to 1mm and "drop" the timber at the centre, and plane from nothing in the centre, to 1mm off at the end, check, and do it again.
Turn the timber round, and "drop" the timber on, and repeat.
I don't think you should be doing this yourself, without some training, as it means either pulling the bridge guard back giving access, with the cutters awaiting any slight mistake, or holding the timber stock in place, above the cutters, guard in place, and start the planer and then "drop" on.
I'm not sure what's on u tube New Brit Workshop perhaps, He's done several reviews on the planer.
This may be covered in a Steve Maskery vid, too.
HTH Regards Rodders