Tips for accurate, repeatable cuts

[Kit B]

A couple of years ago a buddy and I went halves on a used Cook MP 32 sawmill.  In the beginning I was just happy to get the saw from one end of the log to the other.  Unfortunately, I soon realized that the boards I was milling were neither flat, nor acurrate.  So I spent a lot of time on youtube (Thanks yellowhammer, your video on sawing fast and flat was especially helpful) and on the mill learning to adjust the blade guides, properly tension the blade, paying carefull attention to each cut, etc.  I've gotten to the point where I'm cutting flat boards but I continue to have issues getting accurate dimensions.  

I've tried using the measuring tape that is attached to the mill, I've tried using a square to measure down from the top of the cant.  Despite this I'm quite frustrated that it seems like my cuts are a little off.  Measuring seems so fundamental, it's a little bit embarrasing.  I'm milling for myself now, but hope to maybe upgrade to a hydraulic mill and use the skills I'm developing now for a post-retirement gig.  

I'm wondering if folks have any tips, tricks, suggestions for getting repeatable accuracy with manuel mills.  I'm also interested in what people consider to be acceptable variance for rough cut lumber. 

[btulloh]

There are some recent threads on this topic with different ways of making repeatable dimensions. They will probably show up at the bottom in the "similar topics" list, so check that out too.

My manual mill has an indexed wheel on the height adjust crank with holes around the circumference and a locking pin to lock it after adjusting the height. I made up a cheat sheet with a hole count for my normal dimensions for framing lumber, etc.  Very repeatable and fast and works for me.  I put down someting like "3 + 5", or "4 - 6' meaning "three full revs plus 5 holes" = xxxx, and so on.  Might sound cumbersome or slow, but it's not and my dimensions are consistent from board to board and session to session. 

Just one way to do it.  Others have made improved scales and like that approach.  Lots of ways to skin the cat.

[Crusarius]

This is how I started. one tape was zeroed to the bed the other moved. this was useful in trying to make the last board a normal size.


 


Fast forward to less annoying. I put this piece of aluminum on my mill and use a 45 degree cutter to cut the grooves. the first line is 4/4 board, the second it 5/4 the third is 6/4 and the last is 8/4. each one has 1/8" built in for kerf. What I don't show it the movable pointer to replace the moving scale.

I zero the scale to the bed.  that way if I am cutting 4/4 the entire log then the last board ends up being 4/4 if I am cutting 6/4, same deal.

It is pretty easy to jump between scales most of the time. Just know you will get an odd board.

[Machinebuilder]

On my LT15 I have a magnetic scale marked like Crusarius's.
It's one of the things I bought from Woodmizer.

as I'm still learning, I set it to the top of my cant and cut down,
Maybe I would be better to set it to the bottom and have the same size all the way

[Jeff]

What kind of wood, and where was it sourced should be asked. Crooked yard trees, leaners, culls, all can lead to the logs being the culprit. Good logs make good lumber, marginal logs make ???

[YellowHammer]

Thanks for the compliments on the video.  I'm glad you find them helpful.

Accuracy of the cuts is important, as accurately and consistently produces better boards, and it also helps determine and diagnose the "health" of the mill.  Inconsistent cuts should always be investigated to see what the issue is, especially if they are unpredictable.   As people are saying, accuracy of the finished boards can be affected by the accuracy of the measured sawmill head drops, the stress of the log being sawn, and the physical flatness and trueness of the cut.

From what you are saying, the issue you are having now is the accuracy of the sawmill head drop from cut to cut?  or in other words, you want to drop 1 1/8" for example and you're not dropping that consistently?  If you want to "test" your drop accuracy, and eliminate your mill alignment and log stress, simply have a big cant on the mill, make sure the front edge is down on the mill bed and not riding up, do a drop and enter the end of the cant a quarter inch or so, back out, do another drop, enter and back out, and repeat down for the entire face of the log.  When you are done, you should be able to measure the distance between each cut and they should all be the same.  The end of the cant with the cuts should resemble and be as accurate as a ruler, will also tell you how thick your saw blade kerf is, as how accurate your dogboard will be.  You should be able to do this in a minute or so, (just keep the band running) and it will for real tell you how accurate the drops are without all the many other variables getting in the way.  It will also tell you how flat your band is relative to the bed, because if its not, you can easily see it in the dogboard.  Then, if you want to see how repeatable you are, go back up to the top, and repeat it on the same cant, and all the cuts should exactly line up with the previous ones.

This is very easy to do on a hydraulic mill with a good networks, but not so easy on a manual, or a manual setworks.        

[Kit B]

Thanks for all the reply's!  It'll be a couple of weeks till I can get back to sawing, but I'll report back when I do.

[moodnacreek]

In sawing logs into lumber everything is an issue like the style of blade, hardness of log, frost, sap, slope of grain etc. It is a constant struggle. If your last board is about the same as the others you are doing good.

[Old Greenhorn]

This is probably a minor point bordering on the useless but on my manual I have a cable system which controls the head height and I believe this is inferior to the system you have on your machine. There is some slop and shimmy on mine. So each time I drop to the next board, I drop below it and lift back up to the mark I want. This helped me a lot. It eliminates any slop in the system and puts even upward pressure on the lift.
 In fact, the Accuset system on the LT50 I run also drops below and lifts up to each mark, so there may be something to this. OTOH perhaps you already do this and are still having issues. In any event, you have already gotten good suggestions from very knowledgeable folks before I stuck my nose in. Carry on and best of luck.

[jpassardi]

Machinebuilder mentioned the magnetic scale Woodmizer offers with multiple graduations accounting for kerf. You may want to order one. They're reasonably priced.

[KenMac]

Cook's also provides scales for the MP32 and would be the route I'd take to be certain they would fit the structure there.

[SawyerTed]

Simple stuff seems to cause me more grief than big stuff.  These are a few random thoughts.  

The indicator for the scale got loose on my Lt35 and caused my boards to vary.  It would jiggle around.  Tightening it helped.  

Keeping my eye level/position relative to the indicator on the scale consistent when adjusting the blade height.  Aka stand in the same place. 

Mr Old Greenhorn's advice on going below and adjusting up to the desired blade height is sound.  

Don't underestimate housekeeping- keeping bed rails and bunks clean.  Check wheels/cam followers etc to ensure sawdust, trash and pitch aren't accumulating.  

Experience will begin to guide you the more you saw.  

[Nebraska]

 

 

Magnetic scale from Vallee sawmills, the original pointer sitting at the one inch line left a lot to be desired.  I welded a 2 inch finish nail to extend it farther across the scale. It works reasonably well. I will skip the picture as my weld looks like chicken poop. I was out of acetylene and it would've been much better than my old stick welder all the way down. I like this scale better than the cooks magnetic ones as that is what came with the mill.

[YellowHammer]

Despite this I'm quite frustrated that it seems like my cuts are a little off.  Measuring seems so fundamental, it's a little bit embarrasing.  I'm milling for myself now, but hope to maybe upgrade to a hydraulic mill and use the skills I'm developing now for a post-retirement gig.

This is a good mindset.  Get it right, work on it and take pride in your skills.  If it was easy, everyone would do it.

I'll tell you a little story.  When I first started custom milling for others more than a few years ago, the first question I would get from a potential new customer is whether I had a circle mill or a band mill.  When I said I had a band mill, more than one customer would just walk away.  I was new, I didn't have a reputation, and finally, I asked one old timer why people were like that, and he said "Ain't nobody with a band mill can cut straight wood."  

So right then, I found my first real niche into the business, which, surprisingly enough, was pretty basic and still a tenet of our business today.  Cut flat wood and don't ruin logs.  Your business has grown a little since that first LT-15, but it still has the same basic fundamentals that separate us from many others.  Cut Flat Wood.

Many on this Forum absolute top notch sawyers, and that's why I like it here, I'm always learning here myself because these guys are good.  It's refreshing to hear you want to be the best you can also, and great to see the kind of input from all the guys here.  I would assume you watched all of my "Sawing Straight" video, so I guess you saw the "Robert's Rant" at the end.  My wife says I can get a little too intense in those rants, some folks say they are funny because they can tell it has struck a nerve with me, and both are true.  Whether you are a professional or a hobbiest, strive to do the best you can.  There's not enough of that these days, and it will set you apart and put you ahead.  Just my preaching a little.

[Old Greenhorn]

Testify Brother Robert! 8)

[barbender]

FWIW, Brother Robert's testifying motivated me to finally get a BGAT from WM and check my my guide rollers. I had noticed after watching Robert's video, where he pointed out the "rooster tail" should come straight out, that mine was going up a bit. Yep, my guides were tilted up in the front, they're right on now👍

[barbender]

When I pulled that new tool out of the box, it had a sticker on it that said "LTBGAT" I thought at first it was a to for checking or affirming gender😂

[beenthere]

Did you pass the test?   8)

[kelLOGg]

I have had an MP32 for twenty years and once I learned proper tensioning I have been very pleased with the accuracy. 

I made my own magnetic moveable scales and, while not as accurate as set works they do very well - if I remind myself of parallax error. I make sure my eyes are at the same height as the indicator needle by dropping my head a few inches to be at the same level as the needle. 

[moodnacreek]

'Ain't nobody with a band mill that can cut straight wood'.  There used to be a lot of circle sawmills that where just as bad.  Thicker saws are more forgiving especially in easy logs. But the reason for that statement was because at that time portable bands had just come out and the new owners had not learned or quit yet.

[YellowHammer]

Yeah, it kind of dates me a little.  

Just two weeks ago a guy drove up and I noticed he had a bunch of boards already loaded in the back of his truck, which is kind of unusual to show up to a sawmill with wood.  

So he started complaining that he had some boards sawn by another local band miller and the boards were real wavy, basically to the point of being unusable.  I looked at them and agreed, because they were a true mess.  He asked me if there was anything I could do about them, and I said "Yeah, laugh politely and I suggest you don't bring him any more logs."

[jpassardi]

When I pulled that new tool out of the box, it had a sticker on it that said "LTBGAT" I thought at first it was a to for checking or affirming gender😂

;D Barbender: that one gave me a laugh!
You have drank today's liberal Kool Aid... Did the test results surprise you?           Sorry, couldn't resist.
Seriously though, their simple BGAT is worth the 20 or so bucks.

[Wolfgang Rother]

Hi in my Video at 3min 40 i explain how i change the hightsystem the way i do it. It`s in millimeter but u can change it easy to inch.
Frontier OS 31, Blockbandsäge, Sawmill - YouTube

[Gere Flewelling]

I have an MP32 mill and have had good success once I modified the mill to fit me.  I am 6'-2'' tall and found it was necessary to modify the scale pointer height to fit my line of sight.  I cut a couple of pieces of 1/8" angle iron and welded them to the top of the frame holding the magnetic scales.  I also relocated the pointer wire line up so I am looking level across it without bending down.

You can see the weld in the second photo showing how much I raised the scales and pointer.   

 
This keeps the distance that the saw moves very consistent on each cut.  I also found that the magnetic scale caused me to always have to cut a thin shim off the bottom board when sawing 4/4 lumber.  If I moved the scale down to eliminate that shim it then it affected the actual inch scale showing how many inches the saw was off the bed.  I ended up cutting the magnetic scale vertically separating the inch scale from the 4/4 scale.  I then put the magnetic scale back onto the frame being careful to align the inch scale to the distance the saw was from the bed.  This  way I know what thickness I am sawing when cutting posts and special cuts.  I then put the rest of the magnetic scale back on lining the 4/4 scale to where my lowest cut on the mill is.  This eliminated the need to cut a shim off the last board every when sawing boards  and framing lumber.


 You can see how much I adjusted the scales by the "stop" variations at the top.  This has worked out very well for me on this mill.  I also have learned when cutting the each first slab on the first two sides to always line up the cut on the 4/4 scale to help me keep cuts consistent when rotating the log for final cuts.  When I am looking to cut a specific sized post that requires a centered pith. I decide where I want the post to come out of the log and make a mark on the log.  I line up the closest 4/4 cut mark and then count backward on the scale until I get up to where I want to make the slab cut.  This has helped me be as consistent and efficient as possible when sawing in my opinion.  This works well as long as the blades are sharp and guide rolls are properly adjusted.  I do find I need to roll logs after making a few cuts if I notice any tension in the boards coming off.
Note: I did purchase a new inch-4/4 magnetic scale before I cut one lengthwise just in case it didn't work.  I haven't seen the need to use it yet.
This modification is likely specific to this model of mill and this specific scale, but I suspect it might make you MP-32 do a better and more consistent job as well.

[Crusarius]

I forgot, on my aluminum scale I also added an adhesive tape measure, so I have what gere has for an exact measurement off the bed and the cut scales.