PT HELP PLEASE

[dicktimber]

Today for the first time have had time to play with my JET 260 pt.
The blades are set correctly, and when I thickness parallel timber the timber is parallel and square.

When I change over to planing I have a problem.
If I pass some flat, timber with a 1mm cut I am getting a taper along the length of the wood.
The width is ok.
Over a four foot length the taper is very severe, and the blade stops cutting the wood approx half way down the length.

Now both tables look flat when they are aligned with a straight edge, although as I don't have a DTI ( dial clock) to check.
Has anyone come across this before?
OR AM I DOING SOMETHING WRONG?
I never had this problem with my Kity.

Mike

Mike

 

[OPJ]

My first thought is that your outfeed table is fractionally higher than the 'cutting circle' (highest point in knive rotation) of the knives. I assume that, as well as being tapered, the edge is also slightly convex down its length?

Most machines are set perfectly in the factory and very rarely need any work once unpack them (I don't recall wizer or any of the other Jet owners having trouble anyway).

Are you surface planing and edge-jointing after thicknessing? Might be worth lifting both tables back up and blowing away any dust and shavings that may have accumulated underneath (that can also account for alignment issues - DAMHIKT :wink.

 

[CNC Paul]

Mike,

Are the blades level with the back table ?

 

[dicktimber]

Olly,
That's exactly what I am getting tapered and convex.
The knives are just parallel with the outfeed table, not any higher..
If I higher them a tad will that cure the problem?
I always face side and face edge on the planer, then thickness afterwards.
I decided to check to see if it was a problem with the thicknesser as well, that's why I passed a pre planed square parallel piece of timber through the thicknesser, but that's ok.
So I presume it is a table problem???.
And I hold my hand up as it is an Axminster ebay buy and still under warranty.

Mike

 

[woodbloke]

It sounds to me as if the outfeed table is not parallel with the infeed. It should be higher by the doc of course, but you may find the far end of the outfeed table is a fraction higher than the one adjacent to the cutter block - Rob

 

[jlawrence]

I have a similar situation with my PT.
I'm pretty sure it will be down to me not having set it up correctly.

Popped round to screwfix this morning to get a DTI and magnetic base so I can ensure that the blades are set correctly - I'm sure I've (somewhere) a straight reference which I can use to ensure that the outfeed is set correctly.

If you run a search on google for 'woodworking jointer taper' you'll find that it's a common problem.

 

[pryally]

i also get this on my jet jpt-260 - really looking forward to you finding a solution

my infeed/outfeed table appear parallel and the outfeed table is slightly lower than the planer blades at the highest point.

i have several tapered boards now...................

 

[Nick.]

Hi Mike - tapering is something that is in the nature of a jointer I'm afraid - as per video linked below (thank's to jlawrence for pointing this one out - first time I'd seen it)

http://www.youtube.com/watch?v=5af_yZQHo8k

The taper should be minimised though as per all other comments by making sure tables are parallel and outfeed is level with top of blades etc.

Any convex cuts should not be happening and will be down to either tables out of parallel or blades too high

Will say, the video I've linked to is quite patronising - not my intention at all - (quote at end: 'just get over it' - and I love the ironic ending where they implore safety, yet your man does his tablesaw cut with no crown guard...

Hope this helps

Cheers
Nick

 

[Jake]

Hi Mike - tapering is something that is in the nature of a jointer I'm afraid - as per video linked below (thank's to jlawrence for pointing this one out - first time I'd seen it)

http://www.youtube.com/watch?v=5af_yZQHo8k

:shock:

That bloke just doesn't know what the hell he's doing.

 

[Nick.]

:shock:

That bloke just doesn't know what the hell he's doing.

hahaha - hi Jake - sort of agree when it comes to the tablesaw without the guard - I don't think this is an official Jet video? although lots of Jet / powermatic around him? His comments on the jointers capabilities are true though.

ps - Mike forgot to mention, are you changing most pressure when feeding onto the out feed table? That's the reference point to the blades - ie as soon as timber is safely past block, press on timber on outfeed bed to pull the rest past the block - that should leave no convex cuts.

Cheers
Nick

 

[jlawrence]

I honestly can't see why a jointer should produce big tapers all the time. Yes, there are times when it's bound to.
If the machine is setup right and you're using the correct technique you should be able to minimise the taper - at least I think so.

I admit I don't think I've set up my PT correctly yet. But, if I'm only taking say 0.5mm off (max) for each pass then there simply can't be a massive taper. Say I do 3 passes before I'm happy with how flat it is then the biggest difference between one end and another is 1.5mm.
What I don't understand is if I put a test piece on, and joint a straight edge I can still end up with a taper - this surely can only be down to incorrect setup or incorrect technique.
If I'm wrong I'd be very interested to learn why.

 

[studders]

I honestly can't see why a jointer should produce big tapers all the time......

..... this surely can only be down to incorrect setup or incorrect technique.

I think you are right. Before I knew better, and set up my machine correctly, I assumed it came set correctly :roll: ; yet I was making some great tapers and didn't know why. After setting the tables and blade correctly the problems pretty much disappeared.

 

[dicktimber]

The kity I had did not produce tapers at all.
If it was a small, minimal taper fair enough, but this is quite severe on a 4foot length.
I will reset the blades today and report back, as they are level with the outfeed table at the moment,and I used to set the kity so that a piece of flat timber was picked up and moved about 5 mm or so when the blade was moved in an arc.
As olly says, I have a slight convex after planing, so it will reproduce the shape when passed through the thicknesser which is no good at all.

Will report back after doing more checks today.

Mike

 

[moz]

If you are getting a consistent taper on every piece of timber you try it is because the blades are too low relative to the outfeed table (or the table is too high, depeding on your point of view). What happens is that, after cutting, the piece hits and than rides up on the outfeed table until it reaches a point where it falls flat, thereby lifting the rear portion clear of the blades.

It is tempting to think that the blades need to be level with the outfeed table but they need to be fractionally higher. This is because the blades leave a minutely scalloped surface and tne outfeed table needs to be level with the high point of each scallop rather than the low point. One way of checking, with the power off, is to use a straight piece of timber with two lines scored on it, say 5mm apart (though it depends on the diameter of the block). Place the timber with the leading mark level with the edge of the outfeed table. As you rotate manually the outfeed block in a clockwise direction, this should carry the timber forward by the required amount.

If your outfeed table is not adjustable, you will need to reset you knives.

John

 

[OPJ]

On my 10" machine (AW106PT), I've set the outfeed table so that the block moves the wood by 2 or 3mm. I forget which but, I found that if I do it any more than this then I get snipe at the end of the cut.

I'd be vary wary of resetting your knives to match the outfeed table on your planer thicknesser. Whatever you do will have an effect on the accuracy of the thicknesser, since you're using the same cutter block. :? If at all possible, by all means check the knives are set correctly but then, adjust the outfeed and infeed tables to suit.

 

[moz]

I'm not familiar with the model but I just had a look at the Jet website where it describes the infeed and outfeed tables as 'adustable' so, as OPJ says, that's the way to go.

John

 

[pryally]

outfeed table not adjustable on the 'baby' jet.

 

[dicktimber]

Problem solved!!!!
I rechecked the cutter blade heights.
They were set to the height of the outfeed table.
I have now reset them a higher, and used a flat piece of wood straddling the two tables, marked the end of the outfeed table, and rotated the cutter so the wood moved about 3mm.
Then I did the same at the front end, to check the cutting blade was set parallel.
I set the depth of cut to about 1/2 mm.
Then I took a piece of pre planed stock, scribbled a pencil line down the flat face and planed it.
All the pencil mark was taken out, and produced a flat cut.
This afternoon I have stuck some hardwood through, about 6 inches wide, and have again produced flat boards.
These were slightly cupped to stat with.
It surprised me that such a small adjustment could make such a huge difference, but it does.
I thank everyone who took the time to help.
I now need to find a good EN8 HSS supplier that can grind me up a couple of sets of blades, as I have reservations about the quality of the Made in China ones that were supplied.
Thanks again
FROM AN OLD FART
Mike

 

[OPJ]

Pleased to hear you got that one sorted, Mike, but what don't you like about your blades? Is it not worth sending them off for a proper grinding? When I received my Axminster machine, I thought the knives were okay... Until I later had them back from sharpening and couldn't believe the difference! I used to use Dragon Saws though, I'm not sure who to suggest now...

 

[dicktimber]

Olly,
It looks like the blade angle has been ground too steep, and when I put some hardwood through small chips appeared.
There are different grades of HSS.
I use a company (well I used them once for new blades, and several times for re grinds) in Blackburn who specialise in planer blades...well all blades realy.
As they supply the timber industry on a comercial basis I trust them to supply HSS that isn't too brittle, so it doesn't chip, tough, but not too tough that it dulls quickly, and the angle is ground correctly...oh and that all the blades are the same size after grinding.
The last batch were very good.

They also manufacture bandsaw blades. but I don't think they do the narrow bandsaw blades we use.

I just sent off for a price for a couple of sets.
Take a look at their site

www.lancashire-saw.co.uk/

Thanks for the help!
Mike