I just finished my annual tune-up on my 30-YO Delta RC-33 13-inch planer. New knives. Cleaned the bed and all of the rollers, checked roller adjustments, etc. Ran 3 boards to check operation – pine, poplar, and cherry. See photo – have these odd marks on the planed side of all 3 boards. Have never seen these before. Seems that they would have to be made by either the cutter head or the outfeed roller, but these both look fine.
Would appreciate any ideas on the cause of the marks. Thanks!
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That is tear out and is quite common especially in some woods . Try reversing the feed direction for the board. A lighter cut can also help.
yes tear out make sure your new knives are really sharp
It's chip dent. This is caused by poor dust extraction where the chips get caught between knives and surface of the wood. In addition to insufficient suction, it can also be caused by too much knife extension, missing baffle or incorrect positioning of a baffle or too heavy cut.
Thanks for the input here. What do you mean by "baffle?"
I've had this machine for 30 years and have never seen this kind of marks. Wood is very dry. Knives just sharpened. Taking light cuts. 3 different woods, paying good attention to grain orientation - with same results. Have a good dust collection - Oneida SuperCell and short run to the planer.
That's why I'm baffled - why now? Keep the ideas coming! Thanks.
I should have said chip deflector, not baffle. In any event, this is a thin sheet of spring steel or plastic positioned close to the cutterhead which guides the stream of chips into the hood. If present, it usually can be adjusted relative to the cutterhead for maximum efficiency.
I am not familiar with that model so I don't know if that is the case. If there is one present and it is not positioned correctly that could contribute to the problem
Got it. Thanks. I'll check that out.
That is not tear-out. That is chip carry thru, where chips already cut by the knives are caught by the knife and brought back around to be pushed past the board, bruising the board. It happens with inadequate dust removal. Causes include wet wood (makes chips heavier and harder to extract), heavy cut, clogged pipe. Made worse by dull knives as they push the chip instead of cutting thru it. Not sure in your case why you are getting it now.
One knife installed backwards?
Try taking a heavier pass and see if it happens. That will tell you something.
Chip dent. Rollers are compressing detritus into the board.
I wanted to see the 30 YO planer and found this, worth bookmarking since you have one:
https://bullfire.net/Planer/Planer.html
Thanks, MJ. I saw that post this summer. My reaction was WOW, WOW, WOW. The guy did an incredible job overhauling the machine. Impressive undertaking and skills! My machine has been well-maintained and is in good shape.
First of all, thanks to the folks who identified this as "chip dent." That got me on the right path. I found very useful thread on the topic: https://woodweb.com/knowledge_base/Chip_Dent_in_Planed_Lumber.html
I did a lot of trial and error on the different possible causes noted in this discussion. This thread identified one possible cause as "turbulence" near the cutter head - messy air flow - that keeps the chips from clearing properly. So, I taped up a few small joints around the dust hood on the machine. Then I experimented with closing the blast gate a little at a time. With the blast gate closed halfway, the chip dents disappeared. So, in this case the cause was actually too much suction, not too little. Success!
Thanks for the update. I wouldn't have though too much suction could be a problem. I will keep this in mind as I set up a few tools that need dust collection.