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Thickness planer setup

jsdesign

Plastic
Joined
Apr 26, 2017
A friend of mine has an old industrial thickness planer, '40's - early '50's.
20 to 24". Don't remember the name, no manuale or information.
The unit ran well as received. We discovered the feed rollers were jammed in the full up (compressed) position
Disassembled, cleaned and fixed the problem and had the blades sharpened.
Question: what is the rule of thumb settings for the height of blades relative to the feed rollers.
The rollers have to compress to securely hold and feed the board before the blades start to cut and the out feed rollers still have to grip the board after the cut. So , how much should the rollers "step up" onto the board without the knives taking a cut??
 
The times I set up a planer the issue was the maximum distance the planer knives extend from the cutter head. The geometry of the cutter head to the rollers is built in. That means there is a maximum depth of cut. The answer depends on how much pressure the rollers need to bear down on the wood to keep it moving with maximum depth of cut.
 
I don't have the time to write the discourse this needs, but you should research it.

It is less the feed rolls, than the chip breaker (directly in front of the cutterhead) & the presserfoot (directly behind) that have a specific relationship to knife projection.

Depending whether your planer was a "roughing" planer, "finishing" planer, or a kind of general duty machine, the rolls could have as much as an inch or more of range. Pressure on the feed rolls is set independently of depth.

All-powered feed rolls (top and bottom) may take less pressure than top only.

Once started messing with the roll adjustments, whether powered or not, determine where you want the bed rolls for height (depends on service expected from planer, whether finishing or roughing) and make sure they are parallel, etc.

gotta run.
smt
 
I don't have the time to write the discourse this needs, but you should research it.

It is less the feed rolls, than the chip breaker (directly in front of the cutterhead) & the presserfoot (directly behind) that have a specific relationship to knife projection.

Depending whether your planer was a "roughing" planer, "finishing" planer, or a kind of general duty machine, the rolls could have as much as an inch or more of range. Pressure on the feed rolls is set independently of depth.

All-powered feed rolls (top and bottom) may take less pressure than top only.

Once started messing with the roll adjustments, whether powered or not, determine where you want the bed rolls for height (depends on service expected from planer, whether finishing or roughing) and make sure they are parallel, etc.

gotta run.
smt

Thanks for the reply.
Yes there are lots of adjustments. I didn't think to check if the bottom rollers were powered as well, will check.

No manual or knife setting gauge. Am planning to reverse engineer a setting gauge when the rollers are all set correctly.
 
I have an old American Sawmill Monarch 24" planer from that era.
As a starting point set the knives (I have a pair of magnetic knife holders from Wood craft, highly recommended)then set infeed and outfeed rollers and pressure bar even with the knives then lower the infeed rollers 1/4 turn and the outfeed 1/2 turn.

If the pressure bar stops the work, raise it a little. If you get chatter, lower it.

Good luck!
 
Thanks, that sounds like good information.
Since I don't know what the blade height is supposed to be, I was going to try that in reverse.
Crank the table up so a finished board just comes in contact with the feed rollers. Make sure the out feed rollers are a little tighter, then adjust the blades so it takes a quarter turn more to bring the knives into contact. Then make a setting gauge for the blades for the next time.
We'll see what happens.
Thanks again.
 
I always have set the in feed rollers so the marks and depressions of the serrations to be completely removed by the cutter knives. Segmented feed rollers included!

If there is compression of the wood fibers that are not cut away. That will show in the finished work.
 
I don't have the time to write the discourse this needs, but you should research it.

It is less the feed rolls, than the chip breaker (directly in front of the cutterhead) & the presserfoot (directly behind) that have a specific relationship to knife projection.

Depending whether your planer was a "roughing" planer, "finishing" planer, or a kind of general duty machine, the rolls could have as much as an inch or more of range. Pressure on the feed rolls is set independently of depth.

All-powered feed rolls (top and bottom) may take less pressure than top only.

Once started messing with the roll adjustments, whether powered or not, determine where you want the bed rolls for height (depends on service expected from planer, whether finishing or roughing) and make sure they are parallel, etc.

gotta run.
smt

Second all that

Thicknesser.gif


The out feed roller has to have just enough pressure to hold the lumber to the bed even if the underside is uneven. this means maybe 1/16 or so below the lowest point of the bottom knife extension. the in feed is less critical you can adjust it empirically for getting the balance between the best feed and finish. typically if you adjust it for the max depth of cut + a bit you are ok. look at the manual of any similar size planer with the same geometry and follow the instructions. Tweak as necessary.

dee
;-D
 
Here's where i tend to start on a planer:

The beds are often sagged, worn, or simply warped (late Parks machines, some PM's) down in the middle. This can be 1/16" on smallish planers, and sometimes "much" more on wider machines. So essentially the bed rolls provide the parallel reference. Start by surveying the flatness of the bed casting. Then you have to make a determination of whether to plane or grind the bed. Or whether to make a best case adjustment of the feed rolls to the existing bed condition.

Pick the worst end, usually infeed, and determine where you want that bed roll. Then make the outfeed parallel (absolutely no twist)

*Work up from there.

surface grinder flattens planer table - YouTube

I did not have a (metal) planer at the time we ground this PM'r's Powermatic a decade ago. Including twist, sag, and wear, it had well over a 1/16" error, I want to say over .100". Maybe Tom remembers. I never got any finish pics, either; dunno if Tom did or not.

Only thing more tedious than watching a planer run (after the first 5 minutes) is watching a surface grinder....:)

*edited: "work up from there" means that the knives (cutting circle) have to be dead parallel to the bottom feed rolls. This concept will (should) also inform how you set the bed rolls to the cylinder ("cutterhead")while working out how best to address any non-flatness in the bed. In a worst case, the knives do not have to be parallel to the cylinder, but they should be to make setting easier. If they are not, there will be problems or at least "considerations" for setting the chip breaker, presser foot, and powered/top rolls. If there is an installed knife grinder & jointer on the machine, it can be usually be adjsuted or shimmed to be parallel to the bed rols if they are not parallel to the head.

Again, though, once anything is set non-parallel with the cylinder, a whole bunch of other adjustments come into play. So while I described setting the bed rolls and working up, they should be set with thoughtful consideration of other factors, and as close to parallel to the cylinder as possible.

In any event, the planer knives do have to be parallel to the bed rolls or the machine will make different thickness boards across the width.

smt
 

Interesting, it says I modified that 7 years ago but for the life of me I can't tell you what changes I made. The process is one of Bob Vaughan's most repeated works along with band saw tire replacement. I've used his jigs and meathods on multiple planers from 12" to my big 30" Whitney with all powered feed rolls. The theory is sound but the numbers can be a little different machine to machine.

One important thing is that the infeed roll, outfeed roll, pressure bar and chip breaker are all set below the cutter head such that they hold the board before the cutterhead touches it. Without this you not only get a poor finish but it is a safety hazard in that you can get some nasty kickback.

Dan
 








 
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