Thread: How often to sharpen blades on thicknesser?

Originally Posted by Spelunx

I have never had a thicknesser before, and bought a Jet JET-JWP12 last year. I havent really used it much up until now. I have started putting through some 105mm Jarrah reeded decking.

Humm, even if you pressure wash them they could still contain grit in the reeding.

I have been really taking my time with the planing, taking off about 0.25 to .5 mm at a time.

This could be counter productive at 0.25 mm the machine is cutting in the hardened grit zone. On stuff like this or painted surfaces sometimes its better to take as much off as you can,

Before I take it back to the shop, I thought I might check in here to see if it could be the blades? Is there a rough guideline of when the blades need to be changed? ie hours of operation? amount of dust bags emptied?

There's no guideline, one gritty board can be enough to take the edge of the blades.
Even some new timber can still do some damage. Trees growing in a water stress situation can pull up dissolved silica which precipitates out and takes the edge of blades.

Unless there is a chip taken out of a blade a vibrating machine doesn't sound like blunt blades. It could be that one of the blades has moved? Does it vibrate only while cutting or just sitting there?

I do think it's time for a sharpen, but Bob's advice is pretty much spot on - especially about taking more off per pass.

It amazes me how many people think (due to nobody telling them otherwise) that by taking 10 passes at 0.5mm they're putting less wear than 5 passes at 1mm. Unless your blades are RAZOR sharp (which they won't be after the first few passes), they won't actually cut such small increments; they'll just rub the surface and go blunt even faster. If you've ever tried to take an ultra-fine cut using a hand plane with a blunt blade you'll understand what I mean. If you can't hear the motor slow down a bit when using machines, you're not using them properly. End rant.

Originally Posted by BobL

Humm, even if you pressure wash them they could still contain grit in the reeding.


This could be counter productive at 0.25 mm the machine is cutting in the hardened grit zone. On stuff like this or painted surfaces sometimes its better to take as much off as you can,



There's no guideline, one gritty board can be enough to take the edge of the blades.
Even some new timber can still do some damage. Trees growing in a water stress situation can pull up dissolved silica which precipitates out and takes the edge of blades.

Unless there is a chip taken out of a blade a vibrating machine doesn't sound like blunt blades. It could be that one of the blades has moved? Does it vibrate only while cutting or just sitting there?

0.25mm is pretty much all I can take off, more than that and it blows the overload fuse.

I checked for obvious chips out of the blades, or stuff stuck in the blades, but there was nothing there. I don't really want to change the blades, until a technician looks at it.

It is cutting evenly across the full width, i put a wide piece of pine through, and it was an even cut across the width. It only vibrates while cutting.

Originally Posted by elanjacobs

I do think it's time for a sharpen, but Bob's advice is pretty much spot on - especially about taking more off per pass.

It amazes me how many people think (due to nobody telling them otherwise) that by taking 10 passes at 0.5mm they're putting less wear than 5 passes at 1mm. Unless your blades are RAZOR sharp (which they won't be after the first few passes), they won't actually cut such small increments; they'll just rub the surface and go blunt even faster. If you've ever tried to take an ultra-fine cut using a hand plane with a blunt blade you'll understand what I mean. If you can't hear the motor slow down a bit when using machines, you're not using them properly. End rant.

So you reckon that it might be worth putting the new blades in, and seeing if the vibrations stop? I am all for taking more per cut, but between the machine vibrating itself loose, and the crank-handle shaking so much it forces itself back a quarter turn, I don't want to push it any further.

Originally Posted by Spelunx

So you reckon that it might be worth putting the new blades in, and seeing if the vibrations stop? I am all for taking more per cut, but between the machine vibrating itself loose, and the crank-handle shaking so much it forces itself back a quarter turn, I don't want to push it any further.

I think new blades will definitely help.

Jarrah puts a lot of wear on machines, so if you have a fair bit to do I'd try and find someone with something a bit more heavy-duty to run it for you, or you'll be handing over $70 for a pair of blades every 20 metres.

Originally Posted by elanjacobs

I think new blades will definitely help.

Jarrah puts a lot of wear on machines, so if you have a fair bit to do I'd try and find someone with something a bit more heavy-duty to run it for you, or you'll be handing over $70 for a pair of blades every 20 metres.

I hope you aren't correct! I have over 200 metres to get through..... I got told one set of blades would do that.....

i reckon a good plan sounds like to change the blades over, see if that makes a difference, and then take it back to the workshop, if it doesn't make a difference.

Originally Posted by Spelunx

I hope you aren't correct! I have over 200 metres to get through..... I got told one set of blades would do that.....

i reckon a good plan sounds like to change the blades over, see if that makes a difference, and then take it back to the workshop, if it doesn't make a difference.

200m on one set of blades? Tell him he's dreamin'
I hate to be the bearer of bad news, but you haven't got a snowball's chance

Whoever told you that either has no idea about machining or was just plain lying.

If they were carbide tipped blades you'd get it, but not steel unless you can run it in just one or two passes or your machine has enough grunt to run blunt knives (unfortunately, yours doesn't)

Originally Posted by elanjacobs

200m on one set of blades? Tell him he's dreamin'
I hate to be the bearer of bad news, but you haven't got a snowball's chance

Whoever told you that either has no idea about machining or was just plain lying.

If they were carbide tipped blades you'd get it, but not steel unless you can run it in just one or two passes or your machine has enough grunt to run blunt knives (unfortunately, yours doesn't)

Yikes! Sounds like a need to develop a better action plan.

carbide tipped blades are $70, so I can get them no problem.

i will also start washing down the timber with a high pressure hose.

Cheers!

How wide are these boards - I'm thinking 70 mm?

If the motor is cutting out at that width the blades must be very blunt.

If it vibrates only when cutting it could still be the blade position, one might be further out than the other one.

Washing tip. It's better to wash at a low angle, at a high angle the grit can be driven further into cracks etc.

Originally Posted by BobL

How wide are these boards - I'm thinking 70 mm?

If the motor is cutting out at that width the blades must be very blunt.

If it vibrates only when cutting it could still be the blade position, one might be further out than the other one.

Washing tip. It's better to wash at a low angle, at a high angle the grit can be driven further into cracks etc.

They are 105mm.

I guess the only way to establish if the blades are the problem, is to swap them with the new ones I have. Am I right in being surprised at how quickly they blunted though? I imagine there is a bit of grit on the boards, but its not like they are sitting on the ground, and I have been brushing them before I put them through the first time.

Originally Posted by Spelunx

They are 105mm.

I guess the only way to establish if the blades are the problem, is to swap them with the new ones I have. Am I right in being surprised at how quickly they blunted though? I imagine there is a bit of grit on the boards, but its not like they are sitting on the ground, and I have been brushing them before I put them through the first time.

The grit does not need to be obvious, like grains of sand, to dull the blades. Significant wear can be generated very by fine dust ground into the surface of the timber by being walked on, and especially any build up of this in the reed gaps.

Originally Posted by BobL

The grit does not need to be obvious, like grains of sand, to dull the blades. Significant wear can be generated very by fine dust ground into the surface of the timber by being walked on, and especially any build up of this in the reed gaps.

Cheers.... I didnt realise it would make such a difference.

My plan now is to swap over the blades, and run through a few pieces on the almost-completed stuff I have. If it doesnt vibrate or stall, I know it is the blades causing the problem.

If the blades are causing the issue, I dont want to use a set of blades every 20 lineal metres!

So I am thinking I might get out my electric plane, and take off 2-3mm with this, and then finish them in the thicknesser.

The other idea is run them through the Table Saw, take off 3mm, and then finish them off with the thicknesser.

I think the table saw could be easier, as some of the lengths are 5 metres, so it will be difficult to keep it flat over that length for the electric plane.

What do you reckon?

Originally Posted by Spelunx

Cheers.... I didnt realise it would make such a difference.

My plan now is to swap over the blades, and run through a few pieces on the almost-completed stuff I have. If it doesnt vibrate or stall, I know it is the blades causing the problem.

If the blades are causing the issue, I dont want to use a set of blades every 20 lineal metres!

So I am thinking I might get out my electric plane, and take off 2-3mm with this, and then finish them in the thicknesser.

The other idea is run them through the Table Saw, take off 3mm, and then finish them off with the thicknesser.

I think the table saw could be easier, as some of the lengths are 5 metres, so it will be difficult to keep it flat over that length for the electric plane.

What do you reckon?

You'll have to try things out and see what works for you.

The machine is only a toy so what do you expect?