+- Woodnet Forums (https://forums.woodnet.net)
+-- Thread: How flat does a planer bed need to be? (/showthread.php?tid=7378737)
How flat does a planer bed need to be? - DogwoodTales - 06-27-2025
I am refurbishing an old Sears-Roebuck/Belsaw planer. I checked the flatness of the flatbed/table and it's not perfectly flat.
I used a steel ruler as a straight edge (azzuming that it's straight enough for the task), resting it on the table in various directions, and I can see daylight under the edge.
Using feeler gauges it seems to be out of perfect flat between .0004 and .0006 across the width of 12.3” and up to .011 across the length of 18”.
Would you consider that flat enough for a planer, or should I seriously consider having this surface ground to get it flat or flatter?
RE: How flat does a planer bed need to be? - jteneyck - 06-27-2025
(06-27-2025, 10:24 AM)DogwoodTales Wrote: I am refurbishing an old Sears-Roebuck/Belsaw planer. I checked the flatness of the flatbed/table and it's not perfectly flat.
I used a steel ruler as a straight edge (azzuming that it's straight enough for the task), resting it on the table in various directions, and I can see daylight under the edge.
Using feeler gauges it seems to be out of perfect flat between .0004 and .0006 across the width of 12.3” and up to .011 across the length of 18”.
Would you consider that flat enough for a planer, or should I seriously consider having this surface ground to get it flat or flatter?
0.004 - 0.006 probably wouldn't bother me. I'm guessing the 0.011" over the length of the bed is from a low spot in the middle, yes? Whether or not that's a problem can be determined by measuring the thickness on boards you plane to see how consistent the thickness is down the length.
I had a Foley Belsaw planer/molder that had been used so much that it had a visual dish in the planer bed. I didn't want to spend much on it, so I filled the bed with Bondo, scraped and sanded it flat, then glued on a piece of Formica. I used it w/o issue for about 5 years until I sold it.
John
RE: How flat does a planer bed need to be? - DogwoodTales - 06-27-2025
Yes the mid point lengthwise is about .011. .010 slides under the edge without issue but the .011 is a bit tight.
I just checked it again and it seems that as the day warms up this thing gets flatter.
The dip in the middle is now about .06-.07 lengthwise and .004 max across the width.
Maybe getting it tooled would be a waste of money.
Maybe I just need to take a hair dryer to it for a few minutes before using lol
Heck the friction from planning alone might warm it up enough.
It was probably about 75-80 in the shop earlier and now it’s up to 91.