thicknesser snipe

[sunnybob]

I'm very upset that I cant get rid of the snipe on my jet thicknesser.

heres what I got today, this board is 95 mm wide.

Now before I get a lot of replies telling me my tables are misaligned, heres what I've done. Ive taken them both off and put a long flat contiboard tray fully supported.
Like this

I even ran a scrap piece through first and butted this right up behind the scrap.
Anyone have any further suggestion please?

 

[Beau]

Slight over support the exiting piece of wood so slightly lifting it in relation to the block as it ends the cut, very slight though.

 

[pcb1962]

Worth watching Steve Maskery's video if you haven't already

 

[RobinBHM]

Its hard to prevent snip as there is always a tendency for the board to bounce a bit at the end of the cut, even with a perfectly set machine.

I would always advocate making your pieces overlength so the snipe can be cut off

 

[sunnybob]

Steves video focuses on the tables. I have removed them from the equation altogether.

This snipe is appearing on BOTH ends of the wood, even when I pass several pieces through butted up to each other. I think I need to talk to axminster.

 

[ColeyS1]

Slight over support the exiting piece of wood so slightly lifting it in relation to the block as it ends the cut, very slight though.

+1 and the infeed side of it aswell by the sounds of it. Is there a way you can adjust the rollers so they're pushing down a bit more ?

 

[Steve Maskery]

I'd say it was UNDERsupport, not oversupport.

 

[Jacob]

Don't know about your machine but might be spring pressure. Sometimes they get sawdust packed in around and stop working so well. Could be worth having a look at the housings - mirror torch etc? Lift the rollers by putting in a bit of timber (switched off!) and cramping the table up or down with the adjuster.

 

[dzj]

" ...Is there a way you can adjust the rollers so they're pushing down a bit more ?"

Yeah, looks like one roller is not pushing down as hard as the other.
As Jacob recommends, check for dust in the housings.

 

[Noel]

It's lunch box planer (40+ yr old design) and snipe is part of the package although the cutter carriage head lock is designed to help reduce snipe and with the longer infeed/outfeed board you have on it will also help, although might be an idea to make it more rigid. As suggested make your boards slightly longer. Or just use extra small pieces of similar stock ahead of the board and straight after it. Some suggest lifting the stock slightly as it enters and exits the machine but not sure it's worth it. Not sure there's much point in contacting Axminster but might be interesting what they say.
Another option is to use a couple of small batons with lugs (to stop them being fed in) that the cutter head will rest on as it cuts, these are placed each side of the head. The head is supported so there is no "wobble" as the timber enters and exits.

 

[rafezetter]

IIRC Matthias Wandel had an issue with a lunchbox planer and added wood stops to do similar to the lugs idea Djz mentions, lets see if I can find it.. turns out its the lugs system not just blocks.

https://www.youtube.com/watch?v=XdDo3OEtjhc -

 

[chill]

Hi Bob,
you may need to use some support on both the infeed and outfeed sides of the thicknesser dependent on the lengths you are thicknessing. I have roller stands set up both sides of my sheppach p/t this reduces the chance of any wobble or inadvertent dipping as you feed in and guide out your timber and I get very little if any noticeable snipe, you do need to increase their height every time you raise the table though, its good practice to always prepare stock with an allowance at each end for wastage, hth,
Chris

+ 1 for Coley, Beau and Steve Maskery

 

[sunnybob]

All good advice, but I've watched all those videos and built accordingly.
That conti board extension is laid flat to the bottom of the thicknesser. It has under supports both sides and full length, custom fitted to make contact with the top of the cabinet. The planer is bolted down to stop any movement. you could dance on that board without it sagging.

the piece in the picture (I got the width wrong) is only 95 mm x 400 mm long.
I fed in a scrap piece first and then fed three of those 400 mm lengths in by pushing each one hard to the one in front. Then another piece of scrap.

Each of the three pieces shows snipe.

i dont know what else to try.

 

[Steve Maskery]

Bob, did you watch my video all the way through or just the bfirst bit on surface planing? The answer to all your problems is there.
Pushing one hard after the other will never work because it doesn't stop the board that is just finishing from sagging. When only one roller is engaging and the centre of gravity of the board is beyond the table you have to hold the board level. If you don't it will drop, push the tail end up into the cutter block and you get your snipe.
Watch the video again.

 

[Noel]

All good advice, but I've watched all those videos and built accordingly.
That conti board extension is laid flat to the bottom of the thicknesser. It has under supports both sides and full length, custom fitted to make contact with the top of the cabinet. The planer is bolted down to stop any movement. you could dance on that board without it sagging.

the piece in the picture (I got the width wrong) is only 95 mm x 400 mm long.
I fed in a scrap piece first and then fed three of those 400 mm lengths in by pushing each one hard to the one in front. Then another piece of scrap.

Each of the three pieces shows snipe.

i dont know what else to try.

Were the scrap bits the same dimensions as the stock? Otherwise you are essentially saying that the cutter head is taking gouges out of the middle of the stock as each bit passes. Not sure that is possible. The whole idea of using the scrap pieces and feeding all in at once is basically to lengthen the bit you are planing/thicknessing so only snipe at start and end, therefore only on the waste bits.

 

[Noel]

Bob, did you watch my video all the way through or just the bfirst bit on surface planing? The answer to all your problems is there.
Pushing one hard after the other will never work because it doesn't stop the board that is just finishing from sagging. When only one roller is engaging and the centre of gravity of the board is beyond the table you have to hold the board level. If you don't it will drop, push the tail end up into the cutter block and you get your snipe.
Watch the video again.

Steve, on the lunch box type of it doesn't work that way. Sag has nothing to do with it. Reason for snipe is that one roller only has pressure on it at the start and at the end. With pressure only on one roller the cutter carriage swings slightly with the result that the cutter head drops, resulting in a gouge at the start/end.

 

[Steve Maskery]

Feeding in scrap bits will never ever work.

 

[sunnybob]

Steve, the pieces are only 40 cm long. once theyre inside the machine, no way I can lift an end.

Noel, yes, the scrap pieces were offcuts of the same plank.


Havent had a lot of success with this machine right from the start so I've just involved axminster for their opinions, so keep it clean lads, they have the link to this thread.

 

[Brentingby]

Bob, your flat table isn't going to solve the problem of the cutter head assembly tilting at the start and end of the cut. The basic geometry of the planer. When the work enters under the infeed roller, the head gets tilted a bit which means the cutter is lower than the infeed roller. When the work gets to the outfeed roller, the head lifts up and is more level. Then, as the work stops supporting the infeed roller the head tilts down the other way creating snipe on the tail end of the board. It doesn't matter how flat you make the table, it won't change what happens to the head. A lock on the head can reduce the snipe but probably will never eliminate it.

On an old planer, it could be that bushings are worn enough to allow the head to tilt more than it did when it was new.

The solution is to either start with a longer piece of wood knowing you're sacrificing the ends or run additional leading and trailing pieces that are of the same thickness as the stock. some people lightly tack longer pieces on the sides of the stock to support the head at each end.

 

[Noel]

Bob, your flat table isn't going to solve the problem of the cutter head assembly tilting at the start and end of the cut. The basic geometry of the planer. When the work enters under the infeed roller, the head gets tilted a bit which means the cutter is lower than the infeed roller. When the work gets to the outfeed roller, the head lifts up and is more level. Then, as the work stops supporting the infeed roller the head tilts down the other way creating snipe on the tail end of the board. It doesn't matter how flat you make the table, it won't change what happens to the head. A lock on the head can reduce the snipe but probably will never eliminate it.

On an old planer, it could be that bushings are worn enough to allow the head to tilt more than it did when it was new.

The solution is to either start with a longer piece of wood knowing you're sacrificing the ends or run additional leading and trailing pieces that are of the same thickness as the stock. some people lightly tack longer pieces on the sides of the stock to support the head at each end.

Exactly. As I said but with better grammar and a diagram. Part and parcel of a lunch box planer. Although no idea how snipe can appear during the cut.