Hi, I'd say probably no more than say 250/300 max. What I've done in the past is cut the boards to Aprox length then planed it out. I'd say the next project which is the triple bunk beds is going to be the longest boards I've had to deal with. I have 12ft lengths of live Edge at 8,1/4 W @ 3 and 3/4, that's what I'd like to use for the bunk beds. I can square the boards up with my TS jig but it's a lot of hand planing that lol.
I tend to build things for the grandkids like tree houses, outdoor play houses, I've done seesaws and sand boxes 4ft toyboxes that kind of stuff, I've got another 2 grandkids on the way and would like to do as much as I can for them while I still can. I'm 52 and had to retire from work due to ill health.
Cutting to length (leaving a bit of excess for final squaring up) is definitely the way to go. So those ~3.6m (12 ft; sorry I work in metric) boards will be cut down to what length prior to planing? As a rule, most furniture components don’t exceed ~2.5m in my experience. There are probably exceptions but not common. A king size bed frame will likely be less than 2.5m long. A wardrobe probably won’t be much more than ~2m tall, etc.
I have a PT with 310mm wide tables. Machines of this size tend to have a combined length of table (infeed + outfeed) in the range of 1300mm - 1500mm. Meaning that each table is 650 to 750mm long.
You will read general ballpark rules for calculating max board length relative to table length that say 2 x length of the infeed table or 1.5 x combined length of both tables. So for a machine with 1400mm long tables (700 infeed + 700 outfeed) this would give you a max board length of 1400mm - 2100mm. My machine has 1400mm tables and to be honest I think much beyond ~2000mm board length is pushing it, especially in the case of boards that have significant bow (and twist). You need skill to keep the board referencing properly on the infeed as you start the cut and referencing properly on the outfeed table as you finish the cut. The more overhang you have the harder this becomes.
You can add extension tables by drilling holes at the ends of the infeed and outfeed tables and bolting on angle iron with a piece of ply or MDF attached which is carefully leveled with the table surface. These need simple legs to stop them drooping under weight. Doing this will increase the capacity by giving you a longer flat surface to reference off at both ends of the cut. Roller stands are an alternative but these are difficult to level accurately with the tables, especially where the floor is uneven / not flat. They tend also not to be very stable, being easily knocked out of position. Extension tables are a much better bet. Some manufacturers e.g. Felder / Hammer sell proprietary extensions that fit their machines but a DIY mod isn’t difficult if you are careful.
Bear in mind that smaller machines will tend to have shorter tables. So for instance most ~250mm wide PTs have tables that are a combined length of ~1000mm to ~1200mm long. Smaller benchtop models will be shorter still. Smaller benchtop models are also inherently less stable since they don’t weigh much and have a relatively small footprint, hence are more likely to tip if the boards are too long/heavy.
Before you choose a model you need to very clear about the max length of material you plan to work with.
If you are planning on planing material for beds and that may reach lengths of 2000mm then you really want a robust floorstanding machine with long tables and extensions to give you the extra reference surface needed for stability / security.
EDIT: I did a bit of searching online and, in fact, it seems the most common advice is that boards should not exceed 2 x the total table length of the surface planer (jointer). So in my case this would mean boards not exceeding 2800mm. I have to say that I'm surprised by this as my experience is that supporting the board at the beginning and end of the cut when there is a very substantial overhang is tricky and often leads to poor results. Especially if the boards are wide and/or deep and therefore particularly heavy (I work with dense tropical timbers). If the board is bowed then this compounds the issue. I've tried roller stands and they don't do a great job (my workshop floor is not very flat). Hence my recommendation for considering table extensions to add additional support. Perhaps there are techniques for dealing with this problem that I haven't considered. Any advice would be appreciated. I have a large bed frame to make soon using reclaimed Ipê (
ebene verte as its known locally here). Given the weight of this timber I have some concerns about how best to manage the milling process. I work alone. Thanks.
