Introduction: Chainsaw Mill Build, Use & Tips N Tricks
In this instructable we will see how to make a chainsaw mill, how to use it, and discuss some tips and tricks to the hidden and mystical art of planking up fallen trees. Welcome aboard!
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We have recently had some crazy stormage here in the UK, and the number of wind felled trees about is fairly distressing. Much of these trees have fantastic timber that could be used in any number of woodworking projects, but are destined to be firewood, chipped or simply rot where they lay. A chainsaw mill is the relatively cheap and portable way to turn them into some beautiful planks.
If you know you want to build one, you can skip the rest of this intro and get stuck in to step1, or even step 2 if your quite familiar with how chainsaw mills work .
Chainsaw Mill vs Bandsaw mill?
For a long time I didn't want anything to do with chainsaw mills, seeing them as hugely inferior to a bandsaw mill. Chainsaw mills cut with a big fat chain running on a stiff metal guide bar; that gives us a number of disadvantages:
1. the kerf left by the chain (that is the amount of material removed to make a cut) is much greater for a chainsaw mill.
2. Thus it produces far more waste,
3. Cuts are much slower.
4. Chainsaw milling can be (is) hard on the saw. I use an ms440 which has a 70cc engine, this is really on the limit of what you can get away with - bigger is better, though thinner softer wood is obviously easier going. If you love your saw and hate chainsaw maintenance, this may not be for you.
But it has some plus points as well: because the chainsaw's guide bar is relatively rigid, with good technique it can be used to make very accurate, straight cuts, even on huge slabs.
So that's a like for like comparison, and in general the bandsaw wins out for sure. But like most tool choices, the circumstances, and intended use are key. So when is a Chainsaw mill better?
1. It requires much less time and money to build a chainsaw mill, so it is a good choice for hobbyists, DIY woodworkers, and people who might own a little bit of woodland.
2. They are far more mobile than a bandsaw. This means you can take your sawmill to the fallen tree almost anywhere, plank up and carry out... So ideal for restricted access, and steep hilly areas where fallen trees would otherwise be left to rot.
3. Related to that, they don't require expensive heavy duty skidding machinery, and are thus less environmentally damaging (although illegal logging with chainsaws is a different sad story). The waste timber from chainsaw milling can be easily left in situ to nourish the soil.
4. They can be used on odd shaped timber - curved logs and ones with other funky non-conforming features can be planked more easily.
Step 1: Concept
The chainsaw mill, or Alaskan mill as it is sometimes called, is pretty simple. You start with a straight reference edge atop the log you want to plank up (a ladder makes a good straight edge). The 'CS mill", that is the chainsaw mill, which is the jig attachment you build, holds the chainsaw's guide bar (GB) below and in alignment with this straight reference edge. That way you can cut a nice flat surface parallel to the straight edge. Once you have a flat cut into the log you can do the same thing but using the straight edge you just cut, rather than the ladder.
The idea for this mill was to have it very adjustable. Obviously it will be necessary to adjust the distance between the CS guidebar and the guide rails of the CS Mill, as this determines the thickness of the slabs (or in some cases beams, or posts, or whatever) you will cut.
I also wanted to be able to easily adjust the outboard end of the mill to accommodate different sized guide bars. This is a kinda future proofing - especially if your current saw isn't running the biggest guide bar it could, you are likely to want to run a bigger one in the future.
Step 2: Safety
So it goes without saying that chainsaws and their use in general is obscenely dangerous. I am going to assume you, my chainsaw wielding reader, will have a good knowledge of safe chainsaw practice (look here for a brief refresher), and here I will focus on some chainsaw mill specific safety concerns. But remember personal protective equipment (PPE)!! See the diagram of recorded accidents from US Occupational Safety and Health Administration, and and notice how the vast majority could have been avoided with proper chainsaw helmet, gloves, trousers and boots.
In terms of milling I have listed concerns in order of (what I think is) highest risk:
1. The slabs and beams you cut will be very heavy! Shifting and lifting them about is dangerous and often ill considered after the excitement and fury of cutting with a chainsaw mill. Plan route, get help, cut smaller, use machinery if necessary, don't be over ambitious!
2. Chainsaw milling isn't like normal chainsaw use. It takes a long time, and because you are cutting end grain, produces much finer dust. That means a lot of time exposed to LOUD NOISE, VIBRATIONS, DUST, and CS FUMES. Try and cut so that you are up wind of the saw, so that dust and fumes are being carried away from you on the wind. If there isn't a stiff breeze wear a dust mask - Personally I find wearing a dust mask for long periods horrid, so limit my milling to days with a nice breeze. Protect your ears - I use a combo of standard ear defenders AND foam ear plugs. This makes the whole process much more pleasant.
3. Setting up/positioning the log. They can roll and crush! Ideally you want to use a sturdy chocks (you can cut a shape into a log to use as a support). It should also be raised up off the ground or you are likely to get a bad back - but there must be no possibility whatsoever that the log will roll.
4. Prepping the log for milling / cutting off lumps and sticking out branches: if you only have one saw, you will have to take it out of the CS mill and ensure it is fitted with a standard chain (using a rip chain for anything other than rip cutting in a mill is suicide!)
5. Starting and finishing the cuts - a particularly dangerous time - the mill can be only partly supported by the log, and the whole chain is exposed. Use the straight edge for ALL cuts - more on this later.
6. Observers / pets / passers by. Ensure a clear work area and assume you won't hear a curious child approaching - be aware, use signs and cordon off the area if necessary.
7. If you have a helper it is a good idea to guard the end of the chain that sticks out the other side of the log. Also ensure they are kitted up with personal safety gear.
8. There is lots I will have missed - add in the comments please... Stay safe.
Step 3: Cut to Length/ Order Parts
After welding up my first CS mill from scrap steel, I wanted to make a different and improved version from aluminium. This has the benefits of not rusting, being lighter and therefore easier to handle, and more adjustable. I used extruded aluminium with a t-slot profile. It is very versatile stuff, and I like the way it could be re-used in other projects should I not like the results of this one.
The place I ordered the aluminium from in the UK was called KJN (they may not be the best - just the place I used). I used 40mm X 40mm profile size - which is plenty rigid and strong for this application.
Here's the lengths (letters labelled on photo). I use these labels and descriptions throughout so they might be worth jotting down.
A - 2 X 900mm - The long rails - So with this mill the most I will be able to cut is just under 1m wide. These can be scaled as needed.
B - 4 X 400mm - inner bracing
C - 2 X 500mm - the verticals
D - 2 X 100mm - the small vertical alignment pieces
E - one thin (40mm x16mm) length 900mm long, with only one t-slot - the handle (which also strengthens the structure)
Fixings (these are pricey, and quickly add up) Luckily I already had enough bolts:
4 x 40mm x 40mm Angle Bracket sets (I ended up making another of my own).
1 x 10 pack of T Slot Nut 8St M6 with Spring Ball
Step 4: Tap Threads
In order to assemble the frame, both ends of the 4 mid braces (B) need tapping with M8 threads, as does one end of the verticals (C) and the small verticals (D).
It can be quite tricky to get this just right by hand. I used the lathe to line everything up perfect and machine tap them. Obviously it can be done without, and because there are quite a number to do it may be worth making a guide or jig of some kind (or be very skilled). Either way use some WD40 or similar to lube up the tap and clear the chips often. Ensure you get rid of all the chips when your done (compressed air works well, but remember goggles!).
Step 5: Drill Hex Key Clearance Holes.
Once you have tapped your holes you can make reasonable 90 degree butt joints in this kind of profile without any specialist (read expensive) fasteners. To use standard M8 flange head bolts we need to drill a small 6.5 - 7mm hole to allow clearance for the hex/allen key. See the diagram pic which should make this clear (behold the clearance hole drawing!).
The only joint clearance holes you don't want to drill at this stage, are the ones that join the long rails (A) to the third inner brace (B). Where you drill these holes is dependent on your bar length - so first you need to do step 7.
Step 6: Assemble the Mill
Arrange the parts as in the pics. Check for squareness of the joints before tightening, and gradually tighten the whole assemblage.
The verticals (C), must align exactly with the small verticals (D), so that the body of the mill is kept perpendicular to the guide bar. As you see in the photos I use little pieces of hardwood, cut to the exact size of the slot to ensure this.
Step 7: Drill the Guide Bar
To do this we need to make two 8mm holes in the guide bar. This might seem like butchery, but it's not - stay calm. The GB is hard stuff, and you will need a carbide drill bit, some cutting oil, and ideally a drill press. You could probably get away with a hand held drill if it has a slow speed setting (that you usually use for screw driving).
Start by spending a while working out the best position for the bolts. If you have a Stihl Rollomatic GB - the ones with a sprocket at the nose, you want to go right in the middle (see pic). To work out the position of the in-bound hole, draw around a piece of the alu profile. Make it as close to the chainsaw powerhead as you can get it (this makes the CS mill safer with less exposed chain and more controllability). Remember to leave extra room so you can easily swap chains. This bit's important(!), make sure to allow space to adjust the guide bar so you can de-tension and remove a new chain - new ones start out a tad shorter.
To make the holes, mark with a centre punch before drilling. Make sure the guide bar is clamped firmly and has a scrap of very hard wood or mild steel underneath so you don't create a big burr as the drill bit punches through. Make sure you thoroughly clean out all the swarf - no nasty metal bits in the sprocket or groove. De-burr the holes if necessary.
Do I have to drill the guide bar?
You can go to the extra trouble of making a clamp-on system that clamps the mill onto the guide bar without the need to drill it. Lots of people do it this way, and most CS mills sold commercially do it that way. I strongly recommend against this! Here's why:
- Clamps add weight and take longer to build.
- Clamp on systems are more complicated and have more bolts that could potentially come loose.
- They take longer to attach and remove from the guide bar because you have to carefully position them while tightening the screws. In contrast bolt-through attachments self-align the mill onto the guide bar.
- Clamp-ons are usually more bulky, and take up more room. And they necessarily pinch the bar so tightly that they can't be anywhere near the nose area or they would jam up the sprocket. This means the effective cutting width of a given guide bar is much reduced.
- And lastly but importantly, clamps prevent you from quickly removing and replacing your chain, while the saw is mounted in the mill.
Step 8: Mount the Guide Bar and Add a Skid/roller
Now you have drilled the guide bar you can mark up and drill the clearance holes so you can bolt on the last inner brace (B) bit, whose position is dependent on the length of your guide bar.
Once that's done, you can use your long M8 bolts to bolt on the guide bar. To begin with you might find it easier to do this without the chain or the saw's powerhead attached. Remember to use locktite on these bolts, so they can't rattle loose.
On the inbound side, I bolted through an old rollerblade wheel. This helps the mill run smoothly along where it rubs on the nearside edge of the log. Some people also like to fit a rigid 'skid-plate' here instead of a roller. There might be some good arguments for this when the log's surface is particularly undulating, as the wheel can tend to want to roll into the dips. This causes increased forwards pressure at some points and forces you to pull the mill away from the log to make progress at other points. This is not ideal as one crucial element to getting a smooth finish is consistent cutting feed pressure. Anyway, in general I get on quite well with the rollerblade wheel, so haven't tried a rigid skid yet... Share your experiences in the comments.
Step 9: Extras - Grip, Aux Oiler, Throttle Lock
So here's some things that are not strictly essential, but will make the whole process much better.
The grip - sections of old bike innertubes fit tightly over the handle, and help reduce vibrations - Put as many as you can squeeze on over each-other.
The auxiliary oiler - if you're cutting anything over about 50cm, I would recommend an aux oiler. This puts chain oil at the nose of the GB, which is good as a lot of the oil delivered by the saw's on board oiler get's flicked off as the chain makes the sharp 180 degree turn at very high speeds. I use cheap, more environmentally friendly, canola/veg oil in the aux oiler - it works well. For that matter I use it in the saw too, but always make sure to finish the day with a tank or two of proper bar oil (I use Stihl bio-plus), which will flush out the veg oil and won't form hard deposits like veg oil does if you leave it a few weeks. If you're interested in the aux oiler, just ask and I will add more photos & details on the FE facebook page.
Throttle lock - It helps a lot to be able to grip the CS mill in both hands without having to reach down to the saw's throttle. Hence the throttle lock is extremely useful. I use a simple zip tie, which can be slid on and off the throttle. Only use it when you have gone a good way into the cut, and disengage well in advance of finishing a slab.
Step 10: Milling Check List
Items needed Check-list:
- 440 Chainsaw and milling frame
- Tape measure
- Ladder and clamping 2x4"s
- Two precise 2 x 4" spacers for setting up the mill (or whatever size spacers I need)
- Mill Tool kit (hex key to adjust mill height bolts, cordless drill to attach ladder screws, screws, wedges, spare CS chain, scrench, and a few other bits, see the video below).
- Chain sharpening kit for big saw
- Small chainsaw & chain sharpener
- Stihl Chain oil & veg oil
- Fuel mix
- Chainsaw gloves, face shield, ear plugs and CS trousers
- Axe (sharp foresters axe - don't be caught without)
- Tarp/waterproof cover (to throw over kit in case of heavy rain)
- Water (for drinking)
- Clean paintbrush (I use this to clean the dust around the fuel and oil caps before opening to re-fill - very useful).
Step 11: Setup the Straight Edge
To make the initial straight cut you need something straight for the CS mill to follow. There are lots of things you could use for this. People use steel 'unistrut' rails, lengths of straight planed timber, you name it - anything straight. I found my dad's aluminium ladder pretty perfect, and a good compromise between rigidity and weight.
Whatever you use, the chances are you will need to support or attach it to the log in several places. Just the two ends is not sufficient (unless you're milling a short log), as the guide will bow where unsupported. The more contact between the ladder and the log you can get the better! That's easy with straight logs, but more interesting ones can be a challenge.
The end of the ladder is bolted to a length of 2x4 and that's screwed into the end of the log. I also further screw the ladder down through wedges and into the log for the first cut. Make absolutely sure the screws are NOT long enough to be hit by the chain when it makes the first cut. Double check this after setting the height.
Try and make sure the straight edge has a good overlap at the beginning and end of the log - that will make starting and finishing the cut much easier and safer.
Positioning the Log
If you possibly can, raise the log up off the ground - you don't want to be on your knees or bent over the whole time. Also, think slope! Having a slope down the length of the log in the direction you are going to cut helps a lot. Because getting a smooth finish is all about maintaining a consistent mill feed force. So by using gravity to help feed the CS mill we not only do less work, (because the weight of the mill and the tendency of a nice sharp chain to self-feed will be enough) but also achieve effortless consistent feed pressure.
Step 12: Making the First Cut!
1. Check the saw is fully fuelled and has plenty of chain oil - you don't want to stop mid slab to re-fuel.
2. With the saw mounted in the mill, resting on the ground, start it up.
3. With the chain brake on, carry the CS mill to the straight edge and place it on just like you did in the 'dry run'.
4. If you have one, set the aux oiler to deliver at a steady rate.
5. If everything's stable, take the chain brake off, ease the saw on to wide open throttle (WOT) as you start the cut.
6. Guide the mill into the cut. It shouldn't need pushing or much effort, if it does something isn't right, stop and check things over.
7. Concentrate on keeping even pressure on the mill rails so they stay down flat on the straight edge.
8. After about a foot or so into the cut, slide on the throttle lock to maintain WOT.
9. You can now adjust your grip to be better in control of the CS mill. Maintain even pressure.
10. After about 3 - 4ft into the cut, take a wedge from your pocket. Ensure you can control the mill with one hand (it is essential to have the throttle locked or you can't - you may not be able to anyway depending on your particular circumstances, if not just stop). If you can maintain even pressure on the mill, reach behind you and pop a wedge in the kerf - this will stop the top slab pinching the chain.
11. Continue and repeat step 10 as necessary.
12. When you're about a foot from the end, release the throttle lock. Be ready to control the CS Mill as it exits the cut, and the top slab becomes separate. If necessary stop at this point and clamp or screw the slab to the log back at the beginning of the cut (with a wedge in place) - do this if there is any chance of the slab you are cutting sliding when it separates off from the log (if your log is on much of a slope you NEED to do this, or have another way to prevent the top slab moving).
13. Exit the cut. Release throttle and engage the chain brake. Put the mill and saw safely aside and leave to idle (cool down a bit), don't cut the engine immediately after working the saw hard like that. Meanwhile move the slab and stack out the way, get help if required.
You have just made your first slab, hooray!
Step 13: Subsequent Boards
I have recently changed the way I do subsequent cuts. I now simply replace the straight edge/ladder on the flat cut surface, and repeat the process described in step 12. Previously I took the ladder off, and used the freshly cut edge as a guide. Why the change?
Put simply starting and finishing the cut is much easier and safer with the straight edge. Because it overlaps the ends of the log, you can rest the CS mill fully on the ladder, and if the overlap is sufficient you can remove any possible danger of kickback. Yes, it's a little bit more hassle, but it's well worth doing. Without the guide/ladder you have to start the cut with less than half the CS mill in contact with your flat guiding surface - this makes it much more unstable. Don't get me wrong, it's possible to do it without the guide, but starting and finishing without is by far the most dangerous part of the operation, and if a few extra minutes of setup eliminate this risk...
Using the guide seems to have an additional benefit in that it reduces vibrations to the mills handle. This is because the mill is adjusted higher up the verticals (), which seems to mean the vibrations have further to travel from the guide bar to the mill frame. In practice this makes a big difference in vibration levels - cutting a thin board without the ladder, say 1" for example, means the mill frame is only 1" from the chain and vibrations are significant. Using the ladder the mill is about 4 1/2" away from the source of vibration and the vibes are much reduced = operator comfort and less harsh wear on mill assembly.
Step 14: Troubleshooting & Cutting Tips
Quality of cut problems:
Don't seasaw the CS mill through the cut - it doesn't help with cutting speed and causes a gouged finish.
Don't stop or start part way through a slab if you can help it. If you mill without an assistant that means you need (and trust me it makes the whole experience a lot better) a lock on the throttle. I use a very simple zip tie that slides up and onto the throttle. That way you can hold the mill in a more comfortable position, and you can take one hand off for short periods without stopping,to put wedges in the saw kerf.
Slow progress problems:
You will know if the saw isn't cutting well because you will have to push on the mill to make progress. If things are working right you really shouldn't need to do much, the chain will feed itself into the log. Your job will be to 'guide' the mill along.
The most likely reason for slow cutting is a dull chain. If your cutting thick long hardwood slabs expect to swap over or sharpen the chain between each cut! A quick touch up with the file is all it needs - so it is usually quicker to file a number of times before changing the chain.
Bark or no?
De-barking the outbound side of the log helps prevent blunting, but takes quite a bit of time. Personally I only bother with the bark on the far side of the log - it's the stuff that will get pulled right through the cut. And I only bother with it if I suspect it has been on the ground, as it is much more likely to have small stones, sand or mud embedded in it. If you are worried about insect attack on your timber, you may as well remove it at this stage, as you will want it gone before you stack it to dry anyway. A lot of people using the FE workshop like the look of natural edged slabs, so I tend to risk it and keep the bark when I think it's clean.
There are various different chain choices when it come to milling, and there's lots of different views about which is best. A dedicated rip chain has a top plate angle from 0-15 degrees, compared to normal chains which are usually 30-35 degrees. In my experience rip chains cut about the same speed and produce a slightly better finish (less gouges), but are more fussy when it comes to sharpness. They really want to wander as soon as they get dull. When using a rip chain, if it gets dull, even right near the end of a slab, you pretty much have to stop, sharpen or change the chain, and re-start. Standard chains have the advantage that they can be used for cross cutting and other operations safely, and seem much more tolerant when not completely sharp. In general I think I would recommend using a good quality standard chain, especially if you're just starting out.
More important than the type of chain is keeping it properly sharpened, and having the rakers filed to the correct height.
When you have to stop and start?
Despite best efforts, sometimes we inevitably need to stop mid cut to refuel, sharpen the chain, or sort out some other problem. This will likely cause gouges in the finish, but they can be minimised by starting slowly. Don't go WOT straight off and drive into the cut, instead ease the throttle on gently as you steadily re-start the cut.
Step 15: Storing & Stacking
- It takes about 1 year to dry an inch of thickness (this varies lots on the conditions, but can be used to give a rough idea)
- Add stickers ideally of the same kind of wood between boards (if not the same wood, use dry light coloured wood to avoid staining). They should be at least 1" thick for wide slabs to allow good airflow through the stack. 3/4" is ok for narrower boards.
- Space stickers at 400mm in hardwood. You can push this to 600mm if the slabs are 2"thick. I think its best to be safe here, and even if you start a stack with 2" board you may want to add thinner on top (see next point).
- Make sure the stickers are placed one directly above the other, and above the base supports - this keeps the force from the stack acting directly down on the stickers, and not working to deform the boards.
- 'Air dried' wood comes to a moisture content of about 14 to 20 %. If it is to be made into furniture, of other things that need to be 'stable' indoors, it needs either 'kiln drying', or taking inside a month or so before beginning the project.
- Solar kilns are good (check out this one on instructables). Drying kilns that use lots of energy keeping warm = thumbs down.
- Remove sawdust before stacking slabs.
- Mark the slabs with a date and a tree name (e.g. "Ash River Bank" so you can easily pick boards that came from the same tree - and its cool to have the full story of wood when we have a finished furniture project).
Step 16: Cutting Wood
Our world desperately needs more trees! Big trees grow slowly. A century of life giving growth can be killed in a relative heartbeat with a chainsaw. Why this instructable then?
Because using timber to make certain things makes sense from both an environmental and aesthetic perspective. Sustainably managed woodland actually seems to have a higher chance of staying woodland (rather than being cleared for crops or real-estate) when it is managed, maintained and used by people. This instructable is aimed at individuals who want to do something from a wind fallen tree in their or their neighbours back yard. Taking something from tree to finished project can be very satisfying, and help us remain in touch with where the 'stuff' that sustains us comes from.
What I am trying to say is, please don't cut live trees down purely to make boards! Protect our mature trees, for they sustain life on this planet.
Here are some sources of wood I envision this chainsaw mill being suited for:
Wind felled trees. This can be a good source as they sometimes need clearing as they cause an obstruction. If luck is in your favour, you can arrange with you neighbours 'clear up' wind felled trees, doing them a favour and getting some nice slabs in return.
Logs washed up on beaches and riversides.
Other reclaimed sources: beams, old telegraph poles and sleepers, and other sawmill 'waste' can sometimes be used, and could be just right for your project.
Discarded stumps and roots - you might go through a number of chain sharpening sessions, but commercial bandsaw millers avoid them for that reason. See this page for some awesome artsy examples of stuff made from discarded roots.
Interesting curved branches and forks that would be too difficult and awkward for conventional millers to bother with can make just the right part of a project (see photos).
Most of the photos in this instructable are of trees that came from a hedge restoration project I was doing - groups of big trees close together were shading out the understorey, so some of them were taken out. Lot's more saplings were planted for each one removed. Here's an example of some nice window sills we made from milled ash from this project. There's always examples of our latest exciting projects and ideas on the Flowering Elbow facebook page and if video's your thing give me some youtube love and subscribe to my channel.