Accuracy in planing lumber

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Forum topic by oldwoodsale posted 08-18-2013 11:59 PM 1030 views 0 times favorited 5 replies Add to Favorites Watch
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21 posts in 2969 days

08-18-2013 11:59 PM

Topic tags/keywords: planer accuracy grizzly

I just got a new Grizzly 15” planer and was wondering what kind of accuracy I should expect from the unit. I put a digital gauge on the unit and I am not using the standard pointer. When I set the gauge for a thin pass like under .050 I am off by only a few thousands. If I take thicker passes above .050 and with wider boards I am off by .010. I can run it through again, but I have to reset the planer. What I mean by this is I have to unlock the bed crank it down a bit and then back to my original measurement. There seems to be flex in the planer bed caused by thicker cuts. Anyone else have this issue or should I be happy the this performance.

5 replies so far

View TCCcabinetmaker's profile


932 posts in 2350 days

#1 posted 08-19-2013 05:11 AM

most of their machines should have around a 5-7 thousandths accuracy, in this case though you should be able to do a 1/8th inch pass without any flex, if not, then something is loose in the bed and may need tightening, in which case you need someone more experienced with the particular machine to tell you what you need to adjust, as this one is not exactly one I’ve used before.

-- The mark of a good carpenter is not how few mistakes he makes, but rather how well he fixes them.

View Loren's profile


10377 posts in 3643 days

#2 posted 08-19-2013 05:27 AM

Check thickness at several points in the board. Variations
at frame corners are a bugaboo in pro cabinet work. If the
whole job is run through at once, then it’s the consistency
from part to part that matters more than repeatability on
the scale.

View unbob's profile


810 posts in 1898 days

#3 posted 08-19-2013 06:36 AM

Problems with any material cutting machines show up on light verses heavy cuts.
Due to machine/work deflection, a critical finish size is best approached in at least two cuts. First a roughing cut, then a lighter finish cut.
The depth of those cuts would vary due to the machine, and material being cut. The condition of the cutters is a factor also.

View fredj's profile


186 posts in 1813 days

#4 posted 08-19-2013 01:18 PM

All above is good advise. The flex may be due to the feed rollers or pressure bar. I don’t know your machine, but have seen that issue in other planers. Take a few pieces of the same wood that you know are the same thickness. Run one on the far left of the bed, one on the far right and compare. I tend not to trust gages and pointers and go by measurement of what comes out of the planer. It’s also a good idea to work you way back and worth across the width of the bed to ensure even wear of the cutters.

-- Fredj

View mantwi's profile


312 posts in 1891 days

#5 posted 08-19-2013 01:46 PM

I’d look at the bed rollers. I always lower them to flush with the bed and wax the bed to insure a smooth feed. The recommended bed roller height range is between .002 and .020 in my 20” planers manual, that’s a pretty wide range for the factory tech to shoot at and at the upper end flex in the board between the rollers would account for the problem. The cutter head is exerting a lot of pressure on the material. Removing the rollers from the equation should eliminate the issue.

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