what causes a minute ripple effect when jointing kiln dried (7%) cherry.
I changed the blades and checked all adjustments including cutter to outfeed table. Even went so far as getting a new straight edge accurate to .oo1 so what gives.
the jointer is a rigid 6″ 1 year old and i did not notice this before when running wood that had a higher moisture content’
Replies
Dude,
The most likely cause is that the blades aren't cutting evenly, either they aren't all at the same height or they aren't all equally sharp. One other possibility is that you are feeding very fast, but I'd look at the blades first.
John W.
Dude
As always, i agree with John. Whenever I've had this problem, it has always been because the blades were out of alignment, or dull as heck.
Jeff
Mixing "ripple" with power tools is not recommended....
;-)
Regards,
Ken
"Do as you would be done by." C.S. Lewis
I have had the same problem, in my case one of the blades was higher than the others.
Best regards,
Ted
No straight knife planer or jointer cuts perfectly. All leave a slight "ripple" or scalloping. It is the nature of how the machine works. THese marks are usually visible at an angle when looking down the board from the end. Unfortunately we don't really know how "bad" bad is. I have noticed that cherry shows machining more than oak or maple. Dull or mis alligned blades make it worse. To remove it make a pass with a hand plane or much sand paper.
Mike
That ripple is a sure sign that one blade is set higher than the others. Check 'em again.
DR
Think about how jointers and planers cut. The cutter head is moving in a circular path. The blade enters the wood and digs deeper then shallower sort of scooping out the wood. This motion causes the scalloping you are seeing. With rotary cutting, there is no way to get a perfectly smooth surface with planers and jointers.
You can approuch smoother surfaces by being sure your knives are properly set but the best way is to use shallower cuts and increase the cuts per inch. To increase the cuts, you slow down the feed of the board. The slower you go, the smoother the surface. This is the reason for the two and three speed planers you see now days.
When it's all said and done, a machine surfaced board needs to be smoothed by either a plane, scraper or sandpaper before finishing.
Howie,
Or you need a spiral cutter head. I haven't seen any ripple with those and getting a sharp edge on a cutter is just a few minutes work to do.
Frenchy, I would think that a spiral cutting head would just give you ripples that run at an angle rather than straight across the board. It's still a scooping cutting motion and it's impossible to get a truly flat surface with a rotary motion.I don't know of any planer or jointer that gives a finish that is directly ready for finishing.Howie.........
I would like to thank all who have replied to my question .
I will be going over all of your suggestions to see if i can improve my results on this machine .
Thanks again.
Hi Metod,
You are referring to a Fixed knife Surfacer,or Supersurfacer I think. This is a Japanese baby, and I last saw one in use in Germany. They work on the same priciple as your ordinary hand plane .
They are very specialised,expensive and require regular sharpening to get good results.They are really not for the amateur, especially from the cost point of view.
A major disadvantage is that they can only take very small cuts-something like 2 or 3 thou at a time, and foreign stuff like soil, dust etc is fatal: so they cannot process lots of feet per minute, but they can give an excellent finish that does not require sanding or scraping.
It is a very Japanese thing, and no slight meant by that.
This has been a little off the main subject, in which I am interested to see that at least some people are aware of the importance of setting those blades right.
I just extracted this from my store of (useless) information
Edited 5/8/2005 1:26 am ET by mookaroid
Hey Dude,
You always will get ripple or scallopping from a rotary planing machine, by construction.
You can minimise it by1)slower feed rates 2)accurate knife setting 3)keeping the knives properly sharpened.
The theory and practice is that the more cuts per inch you can have the better. That's why a good surfacer or jointer has at least 2 knives and a fast cutter speed or a very high speed cutter head. Look at those industrial machines-you gets wot you pays for.
Is the Rigid direct drive- I mean is it possible to increase the cutter head speed?
The Rigid is belt driven .
Ill take a look to check out the clearance as for speeding it up .
I did use a jig to put in the new knives however im getting a adapter foot for my dial indicater plus a magnetic base asap. to check the accuracy of my set up .
hello again there Dude,
Re the jig you refer to: if this is one of those items supplied by the maker of the machine it is usually nothing more than an after thought, so your dial gauge will be a great help.
Also, even for jointers, most proprietory setting devices register off the cutter head, which can be mis-leading if it is not co-planar with the outfeed table-again your dial gauge will expose this.
Re the speed- don't go over board -I would say an increase of 20%would be about the limit, due to motor power and balance considerations.And it would probably better to increase the size of the motor pulley rather than decrease the diameter of the driven pulley.
Keep us posted.
The jig i have i bought myself
It is plastic and uses 2 magnets to hold it to the outfeed table while 2 more magnets hold the knife at tdc which you find before you start and mark on the fence as a reference.
I managed to get a dial indicator and a magnetic holder now im trying to find a flat foot for the indicator.
Ive seen these somewhere along the way recently but can't seem to locate them now that i need one
Recently i got a 24" steel straight edge from Lee Valley to check the tables ,its accurate to .001" wheras the aluminum one was only good to ..005" it indcated the tables were flat within .001" and on the same plane to each other within .0025 of each other
The Chinese seem not bad at machining somethings lol
Hello Dude,
That jig sounds interesting- seems to incorporate most of the things Ihave been on about.The only uncertainty/potential for variation is the question of top dead centre. I solved this by making mine so that it engaged with slot in the cutter head between the chip breaker bar and the pressure face-stopping each knife at the same position- tdc is not then critical as the out table can be adjusted within reason.Could you send a picture of your jig , even though it is now only of academic interest?
Re your foot for the tdi- it actually should be domed-like a mushroom-about 10mm or so diameter. Have you got a model engineer type friend-it is easy to make from brass.
Re the Chinese tables- the question is -"will they stay straight?".Are you referring to China or Tiawan? I have had bad experience with Chinese stuff but have a Taiwanese shaper which is excellent in every detail.
I have now hatched a plan to grind my blades, including the tungsten ones on my thicknesses, making use of the sliding table on that shaper and some other odds and ends which I have scavenged or cannibalised over the years. The only item I expect to have to buy will be a suitable diamond wheel. If their is interest,and I can learn to post short concise messages, I will put up some pictures.
Not proficient in posting pictures i will see if wife knows how.
The China i was referring to is Tawain (roc} as they like to be called.
A very interesting place to get beautiful hand carved marble and wood.
I visited a couple of factories there and have a few of them .
Here i collect Inuit art and carvings the only problem is they don"t much believe in reproduction in that their art is often one of 30 to fifty and the carvings are one of one so if you se one you like you grab it .
My main claim to fame is not woodworking as you can probally tell ,im just getting into it.
Looking at your profile i see your in New Zelland and former Magaube land very interesting opposites.
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