lucas mill blade wobble.

[scmilling]

Hi all.
Had few issues recently whilst cutting sitka spruce here in Ireland.  Its growth here is very fast leading to soft "hairy" timber,very wide growth ring gaps and lots of tensions. The grain is really raised and hairy around knots. Anyway today whilst cutting a particularly knotty and resinous sawlog noticed the planks coming off were wavy in both horizontal and vertical planes around the knots and when the blade came out of the wood it was oscillating or wobbling quite dramatically. The only way to stop this was to power down, let it stabilise and then restart. Sometimes in the cut the blade would dive down and jam. Othertimes would wander uphill. Plenty of water being used and sharp teeth and tight blade bolts so nothing out of place. Most of the time the saw was cutting really well. If I slowed right down when I saw knots approaching there would be no variation in the cut but pushing on looked like I was using a bandmill. I could see no polish or colour variation on the blade so whats goin on to make it wobble like this? Blade has probably done about 30 hours, been retipped once and is maybe halfway through the current tips. This waviness of cut has happened before but not sure whether the same blade or not.
Any other lucas millers had similar experiences?
Shaun

[Ianab]

Sounds like the blade has lost tension?

A good saw doc should be able to retension it for you.

Usuall cause is the blade getting hot, which could be caused by the stringy and resinous wood. Maybe slightly wider teeth (slightly more kerf) would improve things by giving the blade more clearance?

[longtime lurker]

When you send it to the sawdoctor to get it re tensioned see if they can put another 4 gullets on the blade, then hold those 4 tips at a couple of thou under the 5 original teeth. They need to work as strobes rather then cutters. It'll sever a lot of that hair and let the blade run a lot cooler, besides giving you a smoother finish.
Ain't going to help with knots though, all you can do is slow your feed speed down.

[scmilling]

Thanks for the help so far. Have a real problem here in Ireland regarding saw docs, as its definitely bandmill territory.  The docs I use do the re tipping only, so can't help re tensioning.  They haven't been able to suggest any who can. But im sure with perseverance I'll get there. As most of my work is with the hairy/stringy spruce I may have to look at some sort of strobe blades for the future.  Most logs aren't an issue but some are sheer hell.
The saw is the lucas 10-30, so replacement blades aint cheap. and they're big blades to start cutting extra holes in - won't this make the blade more flexible and temperamental in tough conditions?

[scmilling]

Longtime lurker.
Why 4 strobe type teeth instead of 5 ? How are these laid out on the blade. If you use one of these yourself would you be able to put up a picture or pm me. I don't see images in words too well.
Thanks
Shaun

[bandmiller2]

Scmiller, tensioning of circular saws is common in industry not just in wood working. I would look for a company that cuts aluminum extrusions for say aluminum windows and doors. Find out who services and tensions their expensive tipped saws. If no luck there look for a small company that manufactures saws. Last ditch read all you can find and tension your own, smaller saws have to be easier and less critical than large mill saws. Frank C.

[longtime lurker]

There are five teeth on the standard blade for a 10-30 Lucas. The extras go in between the existing teeth to take it up to a 9 Gullet blade. Set your five cutting teeth as per normal, then set the teeth in the new gullets undersize for length but on spec for width. The extra teeth aren't as effective as proper strobe cutters, but they will give a better finish without dropping feed speed from the combination of faster sawdust removal and raking the side of the cut twice as often.

I don't cut much wooly timber so I've only modded one blade for this, and most the time I run stellites on it with the extra pockets empty for hardwood. I'll grab a picture when I go into the mill next.

[scmilling]

Ah now I understand.
Are your stellite teeth inset with holders or brazed into place.  Been thinking of stellite for quite sometime especially after watching a guy with the only mobile dimension mill in ireland munch through one of his steel log dogs,without much major damage to any teeth.
Thanks for all replies so far.
Shaun

[sigidi]

Shaun, its a long shot but try and contact Stanley Tools over in the UK. They used to have a saw doctor school, my current doc was trained by them and what he knows is amazing. Also surely you have sawmills over there that run circle blades? Ask them who their saw doctor is.

Another way you can go with wooly timber is to use a different profile on your teeth. I wouldn't advise hacking your blades up, doesn't sound like you have saw doctors skilled enough to do it safely. Bloke down here cuts a lot of cedar which sounds a lot like your troubles and he runs a tooth profile much akin to standard teeth with hog and bevel, does a terrific job.

[longtime lurker]

Pics as requested. No teeth in the extra pockets ATM - I braise them in as required. Pockets were cut with a CNC waterjet, and obviously we took great care to keep them exactly the same so as to keep the saw balanced



  

  

 

[longtime lurker]

Ah now I understand.
Are your stellite teeth inset with holders or brazed into place.  Been thinking of stellite for quite sometime especially after watching a guy with the only mobile dimension mill in ireland munch through one of his steel log dogs,without much major damage to any teeth.
Thanks for all replies so far.
Shaun

Stellite vs TCT is one of those horses for course things. We run both here depending on what we're cutting. Each has advantages and disadvantages.

TCT ranges from softer and less wear resistant through to harder and more brittle. For saw teeth there are two standard grades used: K20 and K30. I can't tell you what the chemical composition difference is and its pretty irrelevant anyway - K20 is the most commonly used. It's the harder of the two but also more brittle so prone to chipping.
K30 is softer and requires sharpening more often but it's not as brittle so while it loses its edge quicker it doesn't tend to chip so much. My experience is that I need to retip from chipped teeth more often then I've ever had to replace them from sheer wear so I run K30, individual mileage may vary.

Stellite is totally different to TCT. Again theres a whole range of alloys and I dont do the chemical composition stuff. There are two big pluses with stellite teeth. The first is that they are more abrasion resistant then TCT. We have half a dozen species that we mill that have a tendancy to have very high silica content in the wood. Under those conditions stellite will out cut TCT hands down. It wont hold as sharp an edge as TCT but it will hold its edge a lot longer in those conditions. The other is that stellite is more corrosion resistant and with some species the combination of heat+sap takes the edge off TCT quick in timber that should cut like butter.

But unless you're cutting either abrasive or acidic species then TCT is a winner every time, particularly on the likes of a Lucas where theres not a whole lot of teeth to sharpen anyway.

Ain't no saw teeth that like steel dogs though. :D

[scmilling]

Thanks for your response.
Its really great to have a good review of the advantages or otherwise of the various tooth types.  Likewise to you most of my tooth problems are down to chips and fractures, but my saw doc who doesn't tension, does re tipping and profile grinding very well and cheaply.  I may ask if he will supply the k30 grades and experiment with them for a while. But  I still need to get a tensioning doc organised.
Thanks for the pics and the explanations . They're all a great help to relatively new millers.
Circle mills just aren't that popular in western europe in comparison to bandmills, so the experienced millers are few on the ground and the saw docs who would have once been relatively common  are retired or lost, hence my difficulty in getting help.
Many thanks to forestry forum

[scmilling]

Sigidi ( in particular) but others too.
I'm using the blades as supplied by lucas/central saws , and have had retipping and grinding done to the same profile.  I do note that the newer and hence broader the teeth ,the better they cope with the stringy/hairy spruce, that is my most common type. A newly tipped blade never has the same problems. But after a few sharpens they start to occur
You say try different profiles and mention hog and bevel , these arent terms that my saw doc here recognises and is looking for degrees of grind in various planes. Can you give me a spec on these so I can get him to  grind outside of what I've asked him to do previously. 
Regarding my blade wandering and wobbling troubles I strongly believe as you guys suggest that this one particular blade is out of tension. Have found some circle blade docs up in the north of Ireland, whixh is a different country(!!!) who should be able to help me out, though shipping could cost severely esp with current exchange rates. As I'm still less than a year learning on what isn't a popular mill type I'll probably be asking stupid questions for quite some time. Please bear with me .
Thanks
Shaun

[sigidi]

Shaun, I'll look into the angles for ya.

On the spruce, does the blade have trouble when cutting through the bark in the top and bottom thirds of the log? Down here I find Ironbark bark in the top and bottom third of the log tends to build up and can throw the blade off the horizontal. So to counter this, when cutting through the bark, I make sure I only do about and inch to two inch cut so the bark is cut and then I can cut up to 5" of timber once the bark is cut, but if you try 5" cut running through the bark and into the log, you get problems. Its to do with the different 'size' cut each side of the blade has to cut.

Ya know Lucas do an great tipping jig, if most if your trouble is chipped teeth, might be good to invest in a tipping jig and then you can throw a new tip on here and there whenever you need?

[scmilling]

Thanks for the reply Allen.
Yeah what you've said does have the ring of familiarity to it. I often find myself dropping down a 16th" and using the blade as a planer shortly after opening the log and again  more frequently in the last 1/4 . I'd put it down to the hairy grain rising up and gripping the blade combined with tensions coming out of the wood. I wouldn't have considered the bark on the spruce to be particularly tough but perhaps its simply the differential between the two textures. Certainly most of my problems occur when cutting down a log as I start off removing just a thin skin of bark, but as the girth increases I'm obviously taking out a much larger section of bark and timber. I'll experiment with your method.
Does it make a difference which direction the log is cut, though often there isn't too much I can do about it when the client has piled the logs in whatever mix of orientations suited him on the day.!

[sigidi]

Shaun, butt first or head first doesn't seem to be a problem, I have a preference for having the head of the log at the far end from the operator, but that's just me. I also have my tailer work behind me, so I cut verticle first, then horizontal.

Do yaself a favor, draw a circle (log) now draw a line around the spot you would open the log and stop this line about half way into the log ( cause you have a model 10 and probably take this cut around 4" horizontally, at a guess) now draw another line parallel, but about the thickness of the saw underneath it. Finish it at the middle of the log like the first line. This is basically the kerf of your blade right? Now measure the length of the top line and the bottom line......

The bottom of your blade is taking out what could be 5mm more timber than the top of your blade, doing this the full length of a log could easily end up throwing the blade off - even more so if the blade needs tensioning.

If you do exactly the same kerf drawing around the middle of the log, you'll see both top and bottom of blade cut the same amount of timber, hence why there isn't as much trouble. A badly tensioned blade will hold a better line through the middle,  not as well through top and bottom of log, but not as well as a properly tensioned blade. The tension in the blade helps it to hold its line in these kind of scenarios.

[scmilling]

Thanks again Allen.
I'm wiser today than I was yesterday .
It makes such common sense when thought about, shame I don't use it more often.  I'll try to change the way I deal with bark edges to get the best from the saw.
Regarding my lost tension blade I've finally been put in touch with the saw doc at one of the largest commercial timber plants here ( having been told by another guy that there was no way he'd do outside work ! ) , he's going to take my blade on his way home monday evening and sort it out hopefully.
Yeah I keep considering the the tipping jig, but its one of those extra costs that seem to keep mounting up. Its expensive enough just getting service parts from the agent in UK.  Also if I get the jig then I need to get a gas and torch kit, and a supply of tips ........ the list just runs away.

[sigidi]

Good news, let us know how ya go with the doc