The Forestry Forum

General Forestry => Sawmills and Milling => Topic started by: trimguy on November 26, 2019, 09:37:49 PM

Title: would like some advice
Post by: trimguy on November 26, 2019, 09:37:49 PM
I ordered some 10* blades.they told me the first ones I ordered were 8*, I thought the 10* would be better. I have a 13hp on a homemade mill cutting syp. I tried 3 blades,any idea what would cause this ?
(http://forestryforum.com/gallery/albums/userpics/57881/IMG_1367~0.jpg?easyrotate_cache=1574822212)
 
Title: Re: would like some advice
Post by: redbeard on November 26, 2019, 11:52:01 PM
Pushing the blade too fast comes too mind.
Also that will happen with resharpened blades that are loosing there set, due too several sharpenings.
Can you tell more about the blades your using.
10 need all the HP they can get.
Have you tried going slower in the cut?
Title: Re: would like some advice
Post by: RAYAR on November 27, 2019, 03:24:29 AM
There seems to be several possibilities here. Is your blade getting built up with sap? Also is your blade tensioned enough and what about the blade guide alignment to the to the mill bed?
Title: Re: would like some advice
Post by: kelLOGg on November 27, 2019, 06:48:24 AM
Go with a 4 band. Low power engines (like mine and yours) will cut straighter. IMO the success sawyers have with 7 and 10 is because they have more powerful engines.
Title: Re: would like some advice
Post by: YellowHammer on November 27, 2019, 06:59:09 AM
I agree, I think you should go with less hook angle, not more.  
Title: Re: would like some advice
Post by: moodnacreek on November 27, 2019, 08:23:32 AM
Sounds like the band is 'lifting' due to the 'down pressure' in the cut.
Title: Re: would like some advice
Post by: Old Greenhorn on November 27, 2019, 09:03:12 AM
I am only a year into bandsaw milling however, I do have over 45 years experience with various cutting tools on a very technical level and have studied many ultra slow motion recordings of fast cutting tools and blades in a cut to try to understand how chips are developed and cleared from a cut, where the heat goes, how coolant affects the cut, the effects of the work piece against the cutting tool, etc. Part of my full-time job is diagnosing cutting tool problems and I am pretty good at it. I work in all kinds of metal, but it applies in more than a general sense to wood also. Now having said that, I am not an expert on log milling issues. But I have had cuts like you show in your picture. 
 In order to make a flat cut you need a machine rigid enough to not yield to the cutting forces, a constant blade speed, and good chip removal with minimal heat build up. When you changed to the 10 blades, you increased the load on your machine with a more aggressive tooth. This means there will be more push back from the cut against the blade. This can cause your drive belts to slip or distort and allow the blade speed to slow down a bit, or a lot. If the frame assembly flexes at all, it can allow for a sort of harmonic wave in the blade as it passes through the log. The wider the cut, the worse it gets. The other posters above are all alluding to this. Tightening the blade more may help keep the blade straighter, slowing the cut rate will reduce some of the load on the blade, going to a lower rake angle will reduce the load also and may make the problem disappear.
 I run a 10hp manual mill with 10 blades (a rookie mistake on my part) and it is very sensitive to overloading on wide cuts (12"+), so I take my time with a slow, controlled feed and make sure blade tension, belt condition, and blade lube are all up to snuff.
 My next blade order will either be 4 or 7 degree blades, or both.
 Good Luck
Title: Re: would like some advice
Post by: Den-Den on November 27, 2019, 11:11:01 AM
Are you sure the cut was crooked or is it possible that stress warped the board AFTER the cut?
Title: Re: would like some advice
Post by: Brad_bb on November 27, 2019, 11:24:06 AM
I have the woodmizer 19hp LT15.  I can't run anything but 4 degree bands(I cut hardwood only).  Softwood may be more forgiving, but when you hit knots in softwood, you're running into very hard wood and will likely have waves.  I recommend as others have to stick to 4 degree.
Title: Re: would like some advice
Post by: trimguy on November 27, 2019, 05:14:44 PM
ok. the blades are new ,not resharpened. very little if an sap build up ,I use aspray bottle with 50% bar oil and 50% diesel fuel. its a cut on the log not a board ,so didn't warp after the fact. all my alignment I believe is good. the 8* blades I ordered after this came in today . if things go right I will get a chance  to go and cut Friday .I will double check my alignments and try the 8* blades. sounds like I neeed to order some 4* and try them.thank you every one for your help and I will update with what I find. {I noticed some people in older posts didn't , and feel it hard for others to learn if they don't know the final outcome}. Happy Thanksgiving.
Title: Re: would like some advice
Post by: LeeB on November 28, 2019, 11:11:17 AM
Barreling is caused by a greater feed speed than the blade can cut, especially in wider cuts, or at least this is what I had been taught in relation to a shop band saw. Seems likely it would translate to a mill as well. The blade in essence is deflected back in the middle portion of the cut and remains horizontal at the edges of the cut.
Title: Re: would like some advice
Post by: terrifictimbersllc on November 28, 2019, 09:05:38 PM
Thats what I see as a band gets dull. When wide slabbing I check just that way at end of each cut or with a longer straightedge. If not flat within 1/16 or less I change the band.
Title: Re: would like some advice
Post by: barbender on November 28, 2019, 10:55:22 PM
There's more to how a band performs than just the hook angle. Any 10 blades I've ever used were not very aggressive, nor do I believe that is what is causing your bowed cut. From my experience, I would be looking at band tension, proper guide down pressure, and drive belt tension.
Title: Re: would like some advice
Post by: Brad_bb on November 29, 2019, 12:23:55 AM
Here's a past post of mine regarding waves and knots and hard wood.
What we learned: waves and blade dives (http://forestryforum.com/board/index.php?topic=95719.msg1476309#msg1476309)
Title: Re: would like some advice
Post by: trimguy on November 29, 2019, 07:42:55 PM
thank you for all the responses !! my 8* blades came in and I had a chance to go back to the sawmill.i said I was going to recheck all my adjustments when I went back. having gone thru them when I was fighting with the 10* I decided not to. I just put the blade on because I was curious to know if thats what it was and really how much difference it would make. a world of difference is what it made! I dropped down 1 1/8 ,same log ,same side . perfect cut no crown no waves and with having to spray for pitch every 3-4 feet with the 10* blades , I only had to give a little squirt at the end of each 16' cut through out the whole log. thanks for all the help. still think I need to order so 4* . so any idea what I can use the 10* blades for ? these issues were with SYP.
(http://forestryforum.com/gallery/albums/userpics/57881/IMG_1375.jpg?easyrotate_cache=1575074546)
 
Title: Re: would like some advice
Post by: YellowHammer on November 29, 2019, 07:59:24 PM
Take the 10s and regrind them to 8s or even 4s. 
Title: Re: would like some advice
Post by: 1938farmall on November 29, 2019, 08:19:45 PM
trimguy, did the original 10* blades have the same set as the new 8* blades?
Title: Re: would like some advice
Post by: Andries on November 29, 2019, 08:26:29 PM
. . . so any idea what I can use the 10* blades for ? . . . 
regrinding to 4 degree - or save them for cedar.
Title: Re: would like some advice
Post by: WV Sawmiller on November 29, 2019, 08:52:52 PM
Tulip poplar, buckeye, cedar, etc. I am slowly phasing out all but my 4 degree DH. Even softwood with knots respond better to them IMHO.
Title: Re: would like some advice
Post by: trimguy on November 29, 2019, 09:10:30 PM
I don't know about the set, I haven't checked either, I will when I get a chance. I noticed that the gullet is different from the 8* to the 10*. I guess it would be different on the 4's. if so would that also have to be ground different ? I don't sharpen my own blades. at least not yet ,I do have ideas since I seen one on here made with a radial arm saw. {don't remember who, sorry}
Title: Re: would like some advice
Post by: Southside on November 29, 2019, 11:33:58 PM
If regrinding is not a viable option then I would use them in cedar, or if you have that "suspect" log that just has to be sawn and the odds are decent of finding hidden treasure then open them up with a band that has no real other value to you, nothing to loose if by chance you do strike gold, or iron, steel, ceramic, etc. 
Title: Re: would like some advice
Post by: loghorse on November 30, 2019, 09:43:41 PM
if you use 4 degree for just red oak ,what wouid your set be?
Title: Re: would like some advice
Post by: YellowHammer on December 01, 2019, 08:31:06 AM
25 thou would be fine for a start, that's about where I set all of mine.  You can go more, you can go less, but .025" per side works fine.