thicknesser snipe

[Brentingby]

Noel, i thought your description was perfect even if it missed out the diagram.

There would be a bit of additional snipe behind the front end because the outfeed roller will first ride on the front sniped area so you'll get several steps up

 

[sunnybob]

A good answer, but not one I wanted to hear.
I have also glued longer start / finish bits onto planks with very little success.
Its a disappointment to me that I cant get any better than this from the machine.

This seems to be an inherent design fault. Surely the rollers should be independantly sprung from the cutter head? That would stop the head tilting when different thicknesses were passed under it.

If there is a theoretical solution, i'm not averse to altering the machine as I have no chance of any warranty claims with it.

 

[transatlantic]

So could the solution for a newer design be to have 4 rollers? two before cutter and two behind? That way there is at least two points of contact throughout the operation?

 

[chill]

having looked at your photos again the snipe appears to be within a distance from the end in what would be an allowable amount for waste, this allows for splits and machining faults such as you`re seeing, an old adage is to keep it as long as you can for as long as you can, so hopefully cutting down on waste, when using a natural product like timber it is expected to allow a margin for waste, so its best to try to cut to length after dimensioning the other 4 sides, if you need to cut to shorter lengths before this you should make allowances for waste in your lengths, cutting over size, wood is a natural material that can at times seem as if it has a mind of its own, you maybe take more off of 1 side or it has not been seasoned incorrectly, splitting and warping can occur, unlike plastics and metals etc which are very stable, you also have to work within the tolerances of the equipment you are using, unfortunately a lunchbox thicknesser will not perform as well as an industrial thicknesser in a factory, although they are very capable within their limitations. Go to some of the sheds and look at the par stock they hold and you may well see snipe on the ends of some of the stock and this has probably been dimensioned on a fully automated line. It is good working practice to allow waste and to work within the limitations of your equipment.

 

[sunnybob]

Agreed on that, but sometimes you have to work with what you have, rather than go out and buy another dozen foot of boards just to make a garden table that you have all the offcuts already in your workshop..

On a 40 cm board, to have 10 cm wastage is just not acceptable to me.

I shall study on it.

 

[Jacob]

i think you need a new planer, or a major planer service.
The only other remedy would be to plane up a lot of material one piece after the other to make it continuous, then you'd just get snipe on first and last piece.
In the meantime I'd remove the snipe with a hand plane. It's the sort of thing which happens a lot so it's good to get into the habit.
Cutting to length after dimensioning is not a good idea unless you are talking about short bits added together up to say 1m length but no more. Or you'll end up losing thickness as you try to straighten a long board.
"keep it as long as you can for as long as you can" means use your short lengths, small pieces, of stock first, but you need to cut it to length and rip to size before you do any planing

 

[powertools]

Personally i think that you have a plainer in the lower end of the price range and are expecting it to perform as well as the machines that cost many times more.
We all need to be able to work within​ the capabilitys of the equipment we have.

 

[LancsRick]

Make your last couple of passes very shallow to minimise the effects of snipe.

 

[woodbrains]

Make your last couple of passes very shallow to minimise the effects of snipe.

Hello,

This is sound advice. This, coupled with gang feeding all the pieces in a 'train' so that you'll only get infeed snipe on the first piece and outfeed snipe on the last piece, all the pieces in between will be fine. If you make your last passes ultra fine, you should be able to minimise the snipe to within a couple of hand plane strokes. With some planning, you should be able to thickness to those few strokes thicker, and then, after the handplane, you'll end up with super smooth timber at the correct thickness.

Mike.

 

[MikeK]

The only other remedy would be to plane up a lot of material one piece after the other to make it continuous, then you'd just get snipe on first and last piece.

...gang feeding all the pieces in a 'train' so that you'll only get infeed snipe on the first piece and outfeed snipe on the last piece, all the pieces in between will be fine.

I'm not intentionally singling out any specific replies, but this seems to be a common suggestion. I must be having a dense moment because I don't understand how a train of separate unjoined boards following end to end will eliminate snipe. As soon as the trailing end of the lead board passes the infeed roller, it can rise into the blades because it is not joined or supported by the following board. The same should be true for the following board with regards to infeed snipe.

Unless I am missing something because I'm a novice woodworker, I don't see how the forces of gravity stop affecting a long unsupported board because another board is right behind it. From the thicknesser point of view, each board, whether separated by a foot or butted up to each other, are prone to the same actions as soon as only one roller is in contact. The only way I can see this working is if the friction between the two ends offsets the tendency of the board to move.

 

[Jacob]

You may be right - but on some machines (mine for instance) a sequence of boards end to end goes through as one. I guess it's all about the detail design of the inner workings.

 

[no idea]

If there is a theoretical solution, i'm not averse to altering the machine as I have no chance of any warranty claims with it.

Try lowering the blades if there is any adjustment available on the cutter head so that it at least reduces the amount of snipe that you get.

edit - for clarity, I mean set the blades deeper into the cutter block if this is possible. This works for planer thicknessers where the snipe is caused by the blades being too high relative to the outfeed planing bed. Whilst this isn't the same on your thicknesser it should reduce the severity of the snipe.

 

[woodbrains]

The only other remedy would be to plane up a lot of material one piece after the other to make it continuous, then you'd just get snipe on first and last piece.

...gang feeding all the pieces in a 'train' so that you'll only get infeed snipe on the first piece and outfeed snipe on the last piece, all the pieces in between will be fine.

I'm not intentionally singling out any specific replies, but this seems to be a common suggestion. I must be having a dense moment because I don't understand how a train of separate unjoined boards following end to end will eliminate snipe. As soon as the trailing end of the lead board passes the infeed roller, it can rise into the blades because it is not joined or supported by the following board. The same should be true for the following board with regards to infeed snipe.

Unless I am missing something because I'm a novice woodworker, I don't see how the forces of gravity stop affecting a long unsupported board because another board is right behind it. From the thicknesser point of view, each board, whether separated by a foot or butted up to each other, are prone to the same actions as soon as only one roller is in contact. The only way I can see this working is if the friction between the two ends offsets the tendency of the board to move.

Hello,

The thicknesser cannot tell if the timber is one long piece 10 ft long or 10 pieces 1ft long when they are fed end to end. A 10 ft long piece will only get snipe at the leading end as the planer head engages and snipe at the trailing end when it disengages. The idea of gang feeding is, the operator never lets the planer disengage each piece, only the last one, when there is no timber left to keep the head engaged. It works really well, I had a Jet lunch box planer many years ago and could get excellent snipe free results. In fact they actually work better than people might assume. I could plane quite thin, bandsaws veneers with mine, when set up well.

Mike.

 

[Noel]

Bob, I mentioned earlier about a cutter head lock, you may have missed it. I think the person who designed your machine also missed it. Pity as it helps eliminate snipe.
But reading over your posts I think that you stated that despite gang loading you still get snipe on ALL the boards. Is that the case? If so I cannot understand that, it's the same as getting snipe in the middle of a board. As Mike mentioned above the machine doesn't know if it's one long length or four smaller pieces when gang loaded.

 

[Noel]

Feeding in scrap bits will never ever work.

Does for me and many others.

 

[sunnybob]

Woodbrains... I WAS gang feeding the pieces, and STILL got snipe.

Mikek.... You have missed the fact that the pieces are not long. they are 40 cm. only 15" (approx) in old money. Each piece was touching the piece in front and all were flat on the extended table before and after they left the cutter head.

 

[Fitzroy]

Take the blades out. Run a piece to just after it drops off the back roller then turn the machine off (may take a few attempts to get the timing right) then have a look to see if anything is moving? Is the wood pivoting on a certain point? Can you move the cutter head with your hand or a little leverage. May give you an idea if there is a mechanical issue.

F.

 

[sunnybob]

Fitzroy, thank you. At last, a PLAN.

 

[sunnybob]

I've started another thread because now we have a different approach to the snipe and after several pages people stop reading threads when they might be able to help..
i think I have found a problem, I need opinions from anyone with a technical bent (please, we all know the punchline to that one).

I've removed the covers from the jet thicknesser and closely observed pushing a piece of wood through, with the power disconnected.

The first roller, when it first touches the wood, the cutter head is still about 5 mm away and the roller has to be wound down quite hard to compress the spring enough for the cutter to touch the wood.
That seems logical, move on.

The cutter head does not move. Its firmly located in the main casting, theres no slack. So that rules out some suggestions that the rollers and cutter are pivoted as one unit.

The outfeed roller, now, heres where I think theres a problem. With the first roller lightly touching the wood, the last roller does not touch. theres at least a mm gap, maybe 2 mm. Admittedly when the unit is wound down enough for the cutter head to start to engage with the wood, the last roller does touch the wood, but to me that seems wrong.
After the wood has been cut, the last roller should be lower than the first, yes? to give even pressure on the thinner wood?

Mod edit- New thread merged. Please do not start another thread on the same topic.

 

[Nelsun]

I've been stirring this around in my little brain with little joy. Getting snipe on both ends of chain-fed stock would imply to me that the piece exiting has to be tilting down (to raise the tail end up towards the cutter) after passing the infeed roller. Similarly, the next piece in the chain has to be tilting slightly upwards until it hits the outfeed roller.

My first thought would be the contiboard tray is ever so slightly bowing up towards the block. Not doubting you sunnybob when you say it's flat though. I'd still try chain ganging stock through without the board and see what happens if only to eliminate the tray. Apologies if you've done that already!

Another thought would be to try, instead of putting stock through end on end, to put them through in a staggered pattern:

The idea being both rollers are always in contact with one piece at all times. It won't stop snipe on the first and last piece though.

Everyone loves a good mystery!