Planer thicknesser technique - flattening boards

[Orion801]

Hi all,

I've been trying to flatten some boards today on my planer/thicknesser (a Record PT260X) and have been having some troubles. I'm finding that the boards are forming quite a severe wedge shape. The leading edge seems to be being planed at a bit of an angle, so when I put pressure on it on the outfeed table, it's lifting the back of the board up. I've tried feeding the wood in both ways round and trying both faces but, even if I don't start off with this angled reference at the leading edge, it seems to form after a few passes. Obviously if I keep going I'll end up with a flat board but with no where near enough thickness left at the leading edge, as the flat face will be at such a different angle to how it started.

I think the problem is down to my technique, but I'm not quite sure what it could be. My general process is the following:
- Set the in-feed table to a fairly shallow cut (usually 1mm or less)
- Set the guard to cover the entire cutter block, with the height set a couple of mm higher than the stock that I'm using
- Place the stock face down on the in-feed table and, applying light pressure start to feed this towards the cutter block
- Once an inch or so of stock is showing on the outfeed table, apply moderate pressure to this and pull the wood through

This has worked well for me for the most part, but usually I've been using significantly narrower boards. The one I'm currently trying to flatten is about 250mm wide, whereas others have been less than or equal to 150mm or so.

In terms of machine set up, I haven't given it a thorough checkover yet, but have checked the height of the blades and they seem to be correct and consistent across the width of the cutter block. Everything else I can think of with the set-up was set at the factory and has been fine for all the other boards I've used it on. I want to make sure there's nothing obviously wrong with my technique before starting to blame the tools!

Any guidance would be appreciated, I've had a search through the forums here, and on google, but can't really find anything that explains a solution to the issue I've got beyond setting blade height which I'm fairly confident is correct.

 

[RobinBHM]

If the board has the bow so the concave face is down, it shouldnt be possible to lift the board at the rear end.

Dont pull the work through as soon as enough appears past the guard. Keep working through with light pressure on front and rear table so you are referencing off both tables. If you have a bit of end snipe and push down hard on the outfeed table, the tapered cut will soon develop.

If the board is quite bowed and linger than the tables, take a few inches off each end before doing a full pass. Only do this if your are happy to reverse the board safely, generally only ok if the board is long enough that gravity will make it tip up to the guard.

If you are still experiencing fade out, which is a very common issue with surface planers, then you will need to methodically work through;

Technique.
Check cutters are only a few thou higher than infeed table.
Rear and front tables are parallel.

Note cutters to low or too high can both produce fade out!

If boards are awkward shape, twisted or multiple bows, reversing for each pass can help

 

[Orion801]

Thanks very much for the tips. I'll try passing more through before putting pressure on the outfeed table.

In this case, as I've already tried flipping the board over and turning it round, I don't have a bow as such. It's just thicker in the middle now than at the edges, with both faces being convex. Although being quite wide, it's not a particularly long board (about 350mm). I don't know if this makes things better or worse though.

I'll have another go later and let you know how I get on.

 

[Steve Maskery]

Both faces are convex? Then I think you are going to struggle somewhat, because you don't have any firm point off which to reference.

Can you get one face flat (ish) with a handplane first? That would help.

 

[RobinBHM]

A board 350mm long by 250mm wide and convex both sides is your problem

I personally wouldnt attempt to flatten such a short board.

You could just do it under the thicknesser, use a thick off cut of ply, batten front and back then use some spacers front and back to support the board where its convex and ideally a blob of hot melt glur or some screws through the bottom of the ply if the board is overlength enough.2or 3 light passes will get you flat.

 

[sunnybob]

at 350mm long your trying to swim uphill. Thicknessers just arent made to take boards that small.
The snipe at each end will destroy it.
Get a board at least a metre long, find two pieces of scrap wood very slightly thicker than your desired piece.
Hot Glue them to the big board with yours in the middle, and then pass through the machine.
Or make yourself a router sled and save the thicknesser for full length rough sawn timber.


I see robin beat me by 3 minutes.

 

[deema]

Personally I wouldn't ever go near my planner or thicknesser with such a short board. The double board technique is a possible solution, however if you have a hand plane, by the time you have set up the sleds etc, you will be enjoying a nice cup of tea after finishing flattening it with hand planes.

 

[Orion801]

Thanks for all the help guys. I've managed to get this board flat now, mainly through handplaning. Once it was sitting reasonably flat I ran it over the surface planer a couple of times to finish it off.

Out of interest, you've all said 350mm is significantly shorter than you'd use a surface planer for. For narrower boards I've personally not had any problems with this before, although I have to be fairly careful with my knife adjustment and only take small amounts of material off on each pass to avoid snipe or tear-out. What sort of lengths would you generally recommend as a minimum? Is there any reason that I've not considered as to why I shouldn't to use the surface planer on shorter lengths if the board is convex and sits on the table OK?

 

[sunnybob]

Do you not suffer the thin ends known as snipe? this can often be 5 cm or more on either end.
I dont even try on any length less than one metre.
i find the thicknesser brilliant for smoothing sawn boards to allow finer cuts on bandsaw or mitre saw.

 

[Orion801]

Hi Sunnybob. Snipe seems to be extremely sensitive to knife height adjustment on my machine, but once I've taken the time to fine-tune this adjustment I don't really see any. I have seen it a couple of times but, so far, have always been able to adjust it out.

 

[mbartlett99]

A lot of people commented on technique but you haven't mentioned if this is a new issue or not. Have you checked your tables are parallel - easy for them to get knocked out when you flip the tables.

 

[Steve Maskery]

Snipe on surface planers is due to knives being higher than they should be WRT the outfeed table.
Snipe when thicknessing is down to poor technique.

See here for an explanation.

 

[morturn]

Check your tables set up and make sure that the infeed and out feed are parallel as this is the most common cause of a tapered finish.

There are some adjustment screws on the gibbs to do this; You will need a decent straight edge. If you make an adjustment, then check the blade height afterwards.

Don’t ever move your planer thickness around by pulling the tables.

I have never had a problem planning wood 350mm long, but would not go too much shorter.

 

[memzey]

I have a rough rule of thumb that anything shorter than 2' gets planed by hand.

 

[sunnybob]

Steve, thanks for that, yet another learning curve for me. The thicknesser is the newest of my toys (ooops, tools) and I have not fully got to grips with it yet.
I have the "lunchbox" type, and tried very hard to get both in and out tables flush with the centre platform when I first got it, but it looks like I need to do that again.
I do run 2.5 metre planks through it, so i shall have to work out some extended supports too.

 

[memzey]

I was running 7' boards through my planer thicknesser today funnily enough. I needed the roller stands when planing but just walked round to the other side of the machine to support the board when thicknessing.

 

[sunnybob]

Just found a neat little clip about short boards in a thicknesser...
http://3.bp.blogspot.com/-PM6SMGKhcrc/V ... planer.jpg

 

[andersonec]

If the board has the bow so the concave face is down, it shouldnt be possible to lift the board at the rear end.

Dont pull the work through as soon as enough appears past the guard. Keep working through with light pressure on front and rear table so you are referencing off both tables.

The pressure on the timber must be on the out-feed table once there is enough material past the blade to apply a hold with your pads. If both tables are only a fraction out of parallel then as you press on both tables and feed the timber it will rock and you will end up with a convex piece of wood, all downward pressure must be applied to the 'out-feed table only' it will only reference off that one table and then you will have a nice straight piece.

Andy