Planer Thicknesser Problems! Help

[marku]

Hi

Recently I bought some Elm timber to make a table out of, it was all waney edge and not planed. I considered paying to have it planed but then ended up buying a lurem RD30 on Ebay.

I am having trouble getting a straight board on one side before I put it through the thicknesser, it seems to always have a hollow of a couple of mm in the middle.

The boards are quite long at over 6ft and fairly heavy.

I have checked the planer tables and they seem to be straight, any ideas where I am going wrong would be great before I make any more shavings.

Am I expecting too much from the machine trying to plane boards this long?

I have been trying to plane the face not the edge as in the photo.

Thanks

Mark

 

[Glynne]

Mark
Are you pressing down as you pass the wood over the blade? If the timber is already bowed, then the planer should be taking off wood at both ends if you plane "bow down"' unless you are applying too much pressure as the middle goes over the blades. I used to do this unconsciously until Dodge put me straight and it is easier to press too hard the longer the piece of wood you are trying to straighten.

 

[custard]

Hello Mark, hopefully someone will be along who has this or a similar machine, and can give you specific advice on machine set up.

But if you're still struggling to move on with this project then I'm in Lymington on the Hampshire coast, so if that's not too far from you PM me and you can always bring the timber along to my workshop and we'll dimension it.

 

[marku]

Glynne

Thanks, we are pressing down quite hard, I didn't think that would matter as the timbers 50mm thick so maybe that's the problem.

We have been planning it with the bow up so if you laid it on a flat surface there is light under the middle of the wood, are we doing this the wrong way round?

Custard,

We are not far from you and spend quite a bit of time in the New Forest including crab fishing at Lymington with the boys so would be great to take you up on your offer, but for the meantime I will persevere until the wood becomes too thin. I really don't like to be beaten. At that stage you may find us at your door with beer tokens.

Thanks

Mark

 

[Glynne]

Hi Mark,
Just to be clear, when I say bow down, I mean that the wood would rest on its ends on a flat surface and you would have a gap underneath the middle. I would normally plane with the bow down so as you are taking thickness out of each end. Once this bottom side is flat, you thicknesser will work by taking wood off the middle until the whole piece is an even thickness. Obviously if you have a huge bow, then this won't work and you might need to think about cutting your timber.
Simplistically, try and visualise what thickness of board you could get across the whole length if you were to take a slice which would be perfectly flat and that should give you an idea if you can keep your piece the original length.
Hope that all makes sense.

 

[deema]

To eliminate the human factor, may I suggest that you plane the edge to begin with. Start off with a side which is reasonable straight, and if it has a bow, the bow is up using your terminology. As you pass the wood over the cutter press down ONLY on the wood that has passed over the blade on the outfeed table. Looking at you wood, the thickness on its edge should be sufficient to alleviate any incorrect pressure being applied. If after a couple of passes you have a nice straight board, you can be confident that the machine is working well and it's a technique problem. If this is the case, use the same technique on the face side of the board with a slight deviation. This time, only apply pressure to the first 6" of the board that have passed over the cutter, do not apply pressure anywhere else on the board. When you get to the edge of the planner outfeed table lift off the board carefully, reverse the board and repeat. This is the 'old way' to get rid of a bow, continue the process until the bow has been removed. Now plane straight through keeping pressure on the board immediately after the cutter on the outfeed table.

 

[RobinBHM]

Im assuming you mean it is bowed in the length, rather than cupped across the width? -Its sounds like that as you say you are doing with the bow up, convex fashion.

You will struggle to get the timber totally flat, because it is much longer than the surfacing bed. Any overhang can sit below the edge of table, at either end, so leaving a bow in the timber by this amount.

One way to counteract this is to set the cut to a couple of mm of less, start surfacing about a third of the way along then, raise, retract and if necessary repeat at the same end by 6inches or so. Turn around the board and surface full length. NOTE: do not attempt unless you are comfortable doing this. Make sure bridge guard is less than finger thuckness above the board, is fully across the blade (not conveniently set away from fence for dual face /edging) and do not pass hands over guard.

Even a 2" board will flex, so only use enough pressure to grip sufficiently. Clean and waxed beds with sharp cutters help reduce the pressure required.

Some boards are impossible to get flat and some will move after youve machined down to finished thickness. A 2mm bow on a 2m door stile is acceptable, as long as the bows are paired, so a slight bow may be ok for what you are doing. Thats the beauty of wood

 

[marku]

Great thanks for all the advice, I am going into work early tomorrow and I will try planing the edge first pushing down on the outfeed table, the machine seems fairly square and true, we are used to working with metal lathes and milling machines so setting up the machine is probably OK.

There doesn't seem to be any twist I'm the beds, and they all seem level square etc.

We have been pushing down on the wood on the infeed table.

I think this is a human issue, ie I have no idea what I'm doing. But that's why this Forums so good.

I will report back on my progress tomorrow, at the moment I might open a pet shop to sell all the shavings!

Thanks

Mark

 

[deema]

Hi Mark

Pushing down on the infeed table will not allow the P/T to take out the bow, and I believe is what is causing your problems. You should only ever push down on the outfeed table, and this should only be done in conjunction with thinking how the wood will have been cut by the cutter I.e. Only push down next to the cutter when you are certain that the depth of cut will have cut out any unwanted twist or bow. This then ensures a flat a true board.

I use a scrub plane initially to flatten down the wood before using the P/T if it's badly out. I find this easier and enables me to take off the high spots easier. If it's badly bowed or twisted I use a chalk line to set a datum, and then use a scrub to get the wood roughly flat. It can be both difficult and increase the chances of kick back to try and remove excessive bow / twist from a board on a P/T. If you haven't a scrub plane, an ebay / car boot sourced no 4.5 or 5 is ideal, open up the mouth of the plane as much as possible and curve the blade significantl (top of a yoguart pot makes a good template). No worries about sole flatness, blade finess or any other setup, any old plane can be made into a scrub no matter how tatty it is.

 

[marku]

Hi

Thanks for all the help, this was definitely a case of us having no idea what we where doing.

We had another go this morning keeping, the pressure on the out feed table and had a lot more success. We are still not 100% but we do have some usable timber that would only take a little tweaking with a hand plane.

I think the other problem is the weight and size of the timber compared to the machine we are using, I think it is on the limit and this is affecting the results.

Luckily the chap I bought the planer off also was selling some hand planes which I bought so its off to sharpen the No7 for a bit of finishing, I might also try making a scrub plane from the number 5 1/2.

Great forum for help, I would off been making a lot more shavings and a very small table without the advice.

Regards

Mark

 

[RogerS]

I would also make a temporary outfeed extension. I simply modified my Sedgwick by tapping a couple of threads in the end of the outfeed table to take a couple of small bolts..6mm IIRC maybe only 5mm. The extension table is simply a thick bit of MDF, a bit of aluminium angle at the end drilled to match the bolt spacing in the end of the outfeed table and then the holes opened out to slots so I can easily drop the extension table over the two small bolts screwed into the end of the outfeed table. The other end of the extension has a simple hinge and a bit of wood that drops down vertically. Doesn't need to be mega-strong, just enough to help keep the length of your stock level.

 

[marku]

Roger

We where talking about making the tables longer today but thought that it wouldn't work, so very interesting that your system is successful.

I think we might give this a go, I suppose that it has to be extremely flat to work.

Mark

 

[paulm]

Sounds like you're having fun Mark !

Look forwards to seeing some more pics !

Cheers, Paul

 

[RogerS]

Roger

We where talking about making the tables longer today but thought that it wouldn't work, so very interesting that your system is successful.

I think we might give this a go, I suppose that it has to be extremely flat to work.

Mark

Not really. Your outfeed table is the reference surface. When I put mine in place, I just whack a long spirit level along it and check that the furthest point is level with the outfeed table.

 

[deema]

If the problem is that you are still bowed after the PT, you can extend the tables, but you will need to extend both the infeed and outfeed tables. Using this method the tables must be long enough for the majority of the board to be on both tables as it passes over the cutter. However, as you start the cut, unless the end of the board is on the infeed table you will start to produce a tapered board, the initial cut will be thick, and as the board comes onto the infeed table the bow will lift the board up causing the taper to form. You can continue to extend the taper until the board is flat on one face, however you risk loosing a lot of timber.

The traditional method, used on short tables is to plane both ends as I tried to describe earlier. You plane to the end of the outfeed table, take the wood off the planer, turn it around and repeat the process. This takes down either end of the board at the same rate reducing the curvature until you get to the point where the cutter does not stop cutting. Usually you take a fairly aggressive cut to reduce the amount if taper produced.

This is why I find the trusty scrub plane the better solution, it's less dangerous, the modern methods do not advocate the method I have described as taking the wood off the PT necessitates exposing the spinning cutters. I find that I can adjust the board in a couple of minutes by hand in less time than it takes on the PT and also produce the maximum thickness of useable timber.

Long thin boards are almost impossible to flatten properly on a PT without first doing some hand planing. If the weight of the board causes the board to sag when placed in a flat surface then the PT cannot successfully flatten it. The method to use is to place the board in its side, chalk band mark the board and then do most if the flattening by hand using a scrub plane. You place the board on its edge to prevent its weight affecting the natural bow. Once the board is sufficiently flat that you would move from a scrub plane to say a no 6 you can the use the PT to finish it off.

 

[marku]

Hi,

This hasn't been going well, I think we have several problems but the biggest is the weight and size of the timber some of the pieces are 12" wide and 2 1/2" thick by 7ft long. They are very difficult to handle on the machine.

For this reason we have come up with another plan which I saw in a woodwork magazine a few years ago.

This may or may not work but I think its worth a try, we are going to use a router to on a sled up and down two parallel beams.
Hopefully this will work more like our milling machine, moving the cutter rather than the wood, I didn't get much done at work today as we where quite busy. But there is a picture of progress so far.

Hopefully by holding the wood still using some screws at the ends life will be easier. We will obviously have to make sure we don't twist the boards when we fix them down.

Does anyone have any ideas of the largest router bit available that might work or has anyone tried this method before?

I don't mind using hand tools but this elm is not easy to get through with a hand plane and I am very short of time at the moment so if we can speed things up its a bonus.

Paul, I'm not having much fun with this one, more frustration!

Mark

 

[RogerS]

That size timber is nothing out of the ordinary and you have a good sized planer. Have you tried the outfeed table extension yet? If not then that is where you problem lies. A roller support to give some support on the infeed table would also help.