4 Sider and straightness

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Oneillkev
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4 Sider and straightness

Post by Oneillkev » Fri Feb 19, 2016 4:49 pm

Hi All,

I recently bought a second hand scm sintex four sider. It is brilliant but lately it seems some of the lengths are coming out more like a banana than a strait rule. I just cant figure it out. All feed roller are making contact with the timbers, i am machine mostly 1inch ash/poplar stock down to 65x22 from rough inch thick x 70 in one pass. Machine is well able but it just does not seem to be straightening as it should.

On long 2m or over 1inch stock it actually seems to cause it bend. I thought maybe I was taking to much from one face and causing an imbalance but it seems to happen even in where i do it in two passes.

Anyone had this problem before?

Kevin

Leveller2911
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Re: 4 Sider and straightness

Post by Leveller2911 » Fri Feb 19, 2016 5:18 pm

Oneillkev wrote:Hi All,

I recently bought a second hand scm sintex four sider. It is brilliant but lately it seems some of the lengths are coming out more like a banana than a strait rule. I just cant figure it out. All feed roller are making contact with the timbers, i am machine mostly 1inch ash/poplar stock down to 65x22 from rough inch thick x 70 in one pass. Machine is well able but it just does not seem to be straightening as it should.


Kevin

We have a Paloni RD240 and the first pressure roller is before the first cutter block.

The roller is adjustable so its either pressing down on the timber before it reaches the first cutter block or we pull a lever which makes the roller rise up out of the way so its not pressing down on the timber.

When you're straighening a piece of timber you have the pressure off the first roller. If its pressing down on a bowed piece of timber it won't take the bow out.



Or your timber just has a lot of tension in the grain. I had some Tulipwood recently for a kitchen and 1 1/2" thick boards were pinching the riving knife like a Scotsman hanging on to a £5 note.......

senior
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Re: 4 Sider and straightness

Post by senior » Fri Feb 19, 2016 5:45 pm

Are your blades sharp? if they are blunt the work will ride over them.
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Oneillkev
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Re: 4 Sider and straightness

Post by Oneillkev » Fri Feb 19, 2016 6:42 pm

Thanks for the replies..

Rollers...
Yes I have the first roller raised up so it is not pushing the piece down at all. It seem to straighten ok too just over half way accross the lenght then it just kicks off like a bow.

Maybe it could be tension in the timber but i have not changed my supplier at all and the timber has been pretty good coming out of it untill recent.

Blades.....
This could be an issue. Ill change over the blades and see how that goes. (should have prob done this before now)

podengo
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Re: 4 Sider and straightness

Post by podengo » Fri Feb 19, 2016 10:51 pm

I dont rely on my weinig to flatten thinner stock so generally will do one pass on a surface planer first.

The trade off with feed rollers is that they need a certain amount of pressure to grip and that pressure may flatten out a bow.

I would change knives first on head no 1, then check the knives are the correct height compared to machine bed.

Its a big ask to expect 1" stock to par down to 22mm and flatten. I buy in thicker stock sometimes for wardrobe height stiles, especially in tulip.

I assume you mean flatten rather than straighten. If straightening then thats caused by infeed fence and or in out position of fence head.

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