Modding the BIL mill to take the 880

[BobL]

It was really hot here today again (over 100F) but I started working on adapting the BIL mill to take the 880. Because the 880 bar bolts are further back in the saw body that the 076, the 880 needs to sit further back in the mill frame mount so the oil tank can clear the mill frame. I thought of making another mill specific to the 880. However, given I have more than enough projects on the go for the moment I figured the quickest way to get milling with the 088 is to adapt the current mill

For reference here is the 076 mount.

Two extra long bar bolts pass thru the bar, then pass thru a 1/2 ally spacer plate (to stop the chain rubbing on the mill) and then the bolts pass through the mill frame. Simple, strong and it works. One diasadvantage is the disassembly is messy and the power head and bar tend to bind and all fall apart when removing the power head from the mill.

As I said above, the 880 has a longer body so I could not use the existing bolt holes because the body protrudes and would hit the mill cross bar. However I did work out I could just move the mill back by the distance between the bolt holes so I could at least use an existing hole in the mill.

Step one
Turn one new extra length bar bolt and make a new space plate from 1/2" ally plate.

Step two
Mount bar and space plate plate to saw by the innermost bar bolt.

Step 3
Mount CS onto mill. The mounting process is much easier that for the 076 since the bar is locked to the saw by the short bolt through the spacer plate.

At X you can see how close the saw body (oil tank) is to the mill.

Also show is an existing hole (A) in the mill which will be used to bolt the spacer plate onto the mill. I may also add another bolt at B. The overhang from the space plate at C will be cut back flush with the edge of the mill mount.
The inboard dogs are not in the way but I will probably take them off to save a bit of weight.

I have one remaining problem. Mounting the 076 in this way I could not retain the chain brake as the clutch cover would not fit and so was not used. But the 880 has a more compact inboard chain brake which I would like to keep on . If I do this the chain brake handle is about 1/4" too close to the roller wheel for the brake to be released. A simple solution looks like to cut a small notch in the chain brake handle but that wheel has to be adjustable up and down the vertical so a single notch would not work.

So I will have to take the wheel off and turn off that 1/4" from the wheel - removing that wheel to do this is a PITA as the whole inboard part of the mill has to be taken dismantled to achieve this!

This mounting arrangement loses me about 1.5" of cut width, which annoys me. One solution is just to go to longer bars but I recently invested in a new 42" bar since I found the 42" bar with the 39.5" cut works really well for the majority of stuff I have cut in the past.

I will also need to make some sort of sawdust cover to stop it going all over the place. I have a couple of ideas based on AggieWB's approach.

 

[polexie]

Again a very interesting thread. Bob, it´s nice to see the whole story, from purchase, modding the mill, and of course finally the milling.

Thanks again,

Lex

 

[Brmorgan]

Bob - is that wheel on a bearing so it spins freely? If so, to turn it down you might be able to put a sanding drum in a handheld drill and hold it against the wheel to get it spinning good, and then hold a rasp against the opposite side to take material off. Just a thought, I've done similar things to shave down round wood parts in the past. But I don't know what that wheel is made out of so it may not work very well in this case.

 

[BobL]

Bob - is that wheel on a bearing so it spins freely? If so, to turn it down you might be able to put a sanding drum in a handheld drill and hold it against the wheel to get it spinning good, and then hold a rasp against the opposite side to take material off. Just a thought, I've done similar things to shave down round wood parts in the past. But I don't know what that wheel is made out of so it may not work very well in this case.

That's a very good idea but the wheel is made of teflon which is very slippery (which is why it does not need a bearing) and that makes it a bit of a pig to work. I will take the mill apart and put the wheel on my WW lathe. I can hold the inner radius using a pin chuck, wrapped in 80 grit sandpaper and use a really sharp ww chisel to to turn it back. We have great scraps of telfon and other exotic plastics in the scraps bin at work, I would use it more often if it was not difficult to work.

 

[BlueRider]

The few times I have used my 038 for milling I didn't like the way the radiated heat from the exhaust bounced back into the saw. Even the mill itself would heat up a fair bit. The exhaust ports on the 038 do difect the exhaust to the side but I always thought if I were going to mill more with the saw I would do a muffler mod.

After seeing the way Andy is modding the 361 muffler I even thought about doing that to my 051 and 075 to direct the exhaust further away when the saw gets closer to the botom of the log and bounces the heat back up into the saw.

looking at that big beast and how close the muffler is to the mill I will be curious to find out if you have any heat issues.

I can see how it is a matter of principle for the chain brake but at the same time I don't see how a traditional chain brake would be of any value on a dedicated milling set up. How could the saw kick back and trip the brake? I could see how it might be a nice safty item if it could be trigered from someplace other than the tight confines of where it is located, like from one or both hand holds, or even a panic bar on the trailing edge of the mill. Don't mean to knock you Bob and I only bring it up because you are such an out of the box designer on the rest of your mill.

I know the second bolt at the power head end of the mil will bother you until you add it, but with one bolt on each end the mill can't twist or move in or out. it really isn't necessary.

I read an interview with an Aussie boat builder who set the sailing speed record, somewhare around 50 knots if I recall. he would make a part and put it on the boat and go sail if it didn't brake he would make it lighter and thinner and sail some more. he would keep doing this until the part would brake and then make the final part just a bit stronger. after his speed record he was invited to be on the Australia design team to defend the Americas Cup trophy. he eventualy resigned because they were designing on a computer and testing with computer models and he couldn't find the real world limits with a computer model. I liked this story for its out of the box kind of thinking, but still having that real world criteria of finding the real breaking limits of a design and without that the design coudn't be the best it could be.

I know what we do cant affor this kind of failure testing but at the same time we need to rememeber the words of Voltaire- don't let perfection become the enemy of good.

 

[BobL]

Thanks for the detailed feedback BlueRider, it's much appreciated

The few times I have used my 038 for milling I didn't like the way the radiated heat from the exhaust bounced back into the saw. Even the mill itself would heat up a fair bit. The exhaust ports on the 038 do difect the exhaust to the side but I always thought if I were going to mill more with the saw I would do a muffler mod.

After seeing the way Andy is modding the 361 muffler I even thought about doing that to my 051 and 075 to direct the exhaust further away when the saw gets closer to the botom of the log and bounces the heat back up into the saw.

looking at that big beast and how close the muffler is to the mill I will be curious to find out if you have any heat issues.

Yep I too have a concern about this. I think the 076 has a good exhaust location where the exhaust is directed down away from the operator. Even with the wind blowing towards the operator very little exhaust is sent back to the operator. I don't have a problem with "when the saw gets closer to the bottom of the log and bounces the heat back up into the saw." because I always lift my logs off the ground. I also very rarely place the mill on the ground - always on another log or preferably on my mobile work bench I usually take with me to the field.

While using the big Husky recently (same exhaust location as the 880) the first thing I noticed when I was using it in a slab and leaning on the top of the wrap handle with my left knee was something hot between my legs. This was of course the exhaust and on cutting long slabs it was simply not possible to do this for more than a few feet - I was worried my chaps would melt. On big logs I like to lean on the saw with my hip, same problem.

Then with the wind blowing towards the operator the exhaust would swirl up under my face shield into my face. I always try to orient the logs downwind but sometime the terrain is not conducive to this arrangement.

So in summary the exhaust location does worry me - I'd prefer not to be wearing a gas mask and melting my chaps. So some sort of a muffler mod is definitely lurking in the wind.

I can see how it is a matter of principle for the chain brake but at the same time I don't see how a traditional chain brake would be of any value on a dedicated milling set up. How could the saw kick back and trip the brake? I could see how it might be a nice safty item if it could be trigered from someplace other than the tight confines of where it is located, like from one or both hand holds, or even a panic bar on the trailing edge of the mill. Don't mean to knock you Bob and I only bring it up because you are such an out of the box designer on the rest of your mill.

No worries - any comments are good because they help me continue to weigh up the ideas around in my head.
Your comments are pretty much the way I'm thinking.

I'm not worried about kickback but I am a little worried about picking up and moving the mill with the running engine. I'm one of those people that applies the brake when taking more than a step or two with a running CS. Normally I perch the 67 lb mill and powerhead on the log rails, start the engine and off I go - at the end of the slab I leave the mill perched on the end of the rails and keep the engine idling for the power head to cool for 30s or so off before turning it off. The mill is thus carried with the engine off.

I normally use rails for every slab but there are occasions I don't - then I start the engine on the log and pick up the mill with the engine running walk over to the log and hold the mill up to the log and do a "no log rail" start. I would prefer to perform the walk to and from the log with the chain brake applied. I know the risks are very low because of the mill frame surrounding the chain but there you go.

Another situation I would find it useful is when the mill is "into the cut" and I having to put my hand on/near the chain (maybe to clear a big chip or dirt) with the engine running. Being able to flick the chain brake on before doing that would be good OHS practice. Another reason for all this is I find myself being asked to show others how I do things. With a long history of teaching behind me, I find things need to be explained and even exaggerated to the "average joe" for it to sink in. I really push the OHS stuff when showing people milling and as most people will use conventional mills with chain brakes it would be useful if I could practice what I preach.

Because I would not be using the brake lever as an anti-kickback device I like your suggestion of replacing the lever with something shorter. I may still do this.

I have no problems with others using a CS mill without a brake. I think the biggest risks in CS milling are in moving the logs, lumber and slab saround more than the saw.

I know the second bolt at the power head end of the mil will bother you until you add it, but with one bolt on each end the mill can't twist or move in or out. it really isn't necessary.

Agree.

I read an interview with an Aussie boat builder who set the sailing speed record, somewhare around 50 knots if I recall. he would make a part and put it on the boat and go sail if it didn't brake he would make it lighter and thinner and sail some more. he would keep doing this until the part would brake and then make the final part just a bit stronger. after his speed record he was invited to be on the Australia design team to defend the Americas Cup trophy. he eventualy resigned because they were designing on a computer and testing with computer models and he couldn't find the real world limits with a computer model. I liked this story for its out of the box kind of thinking, but still having that real world criteria of finding the real breaking limits of a design and without that the design coudn't be the best it could be.

I know what we do cant affor this kind of failure testing but at the same time we need to rememeber the words of Voltaire- don't let perfection become the enemy of good.

I agree one can go too far - I have done that more than once. One thing I know for sure my mills are far from perfect eg; some bolts are not properly located so I cannot get ring spanners around the heads, there is a surplus of weight resulting from over engineering, and do you thing I can get my aux oiler to stop leaking !!!!! no way. One time it leaked a whole pint of oil all over the inside of my van. I parked the van pointing uphill and hosed it out like a pigtruck!

 

[Brmorgan]

Because I would not be using the brake lever as an anti-kickback device I like your suggestion of replacing the lever with something shorter. I may still do this.

...

I have no problems with others using a CS mill without a brake. I think the biggest risks in CS milling are in moving the logs, lumber and slab saround more than the saw.

...

I agree one can go too far - I have done that more than once. One thing I know for sure my mills are far from perfect eg; some bolts are not properly located so I cannot get ring spanners around the heads, there is a surplus of weight resulting from over engineering, and do you thing I can get my aux oiler to stop leaking !!!!! no way. One time it leaked a whole pint of oil all over the inside of my van. I parked the van pointing uphill and hosed it out like a pigtruck!

I was about to suggest tossing or replacing the chain brake handle but didn't want to be the one to catch all the flak from the PPE nuts. :bang: Also while I think older saws look better without them, for some reason the new ones don't look right.

I'm with you on the bigger risks being in moving the wood and equipment. There have been a couple times where I almost lost control of a cant hook, which would have resulted in me being pinned by a log that I'd never move alone if that happened. Not to mention it would have likely crushed my leg(s) or worse. One was a 20' section of 28" Douglas Fir, must have weighed a ton or more. I do always keep my cellphone in my pocket just in case, but still it worries me.

Where is your oiler leaking from? Out of the filler hole or the drain end at the bar? It's been a while since I looked at pics of your oiler setup so I don't remember exactly what it looked like, just the general idea. I made a similar (though much more unsophisticated) oiler on the 4-stroke CSM I built a few years ago. I just used an old fire extinguisher as the tank, inverted it, drilled a hole in the bottom (now the top) and J-B welded a fitting to it as a filler cap. For the drain I just put a ball valve directly onto the extinguisher's neck with a barb fitting on the other end, and ran a hose from there down to a fitting on the bar. However I had lots of extra hose so there is a "gooseneck" section similar to your sink drain's plumbing. The oil tank has been sitting for two years untouched and still looks as full as I left it.

I think what's happening is when I shut off the ball valve, gravity siphoned the hose empty except for the gooseneck section, and this full section of hose is keeping more from siphoning out. Those ball valves create pretty much a perfect seal too, so that helps. I also put a small vent on the tank to keep it from getting either a vacuum or too much pressure from heat. Whatever the reason is, it seemed to be the part of the mill that actually worked like it was supposed to! I'm starting to get excited about rebuilding it this summer if I can't secure a bandmill. I know I can make it work this time.

 

[BobL]

Thanks for the feedback brad.
I agree the old saws do look better sans brake.
If the saw didn't have a brake it wouldn't bother me, but seeing as it does and I have to locate the saw further back in the mill frame to clear the powerhead oil tank it's no biggie to leave it there.

Where is your oiler leaking from? Out of the filler hole or the drain end at the bar?

It leaks from just about every fitting underneath the tank.

As you can see they form a bit of Christmas tree and so vibrate quite a bit.
The brass fittings are air fittings and I tried using teflon tape to seal them but the oil just seems to dissolve the tape. I then used loctite which works up until I knock one of the joints. That seems to let the vibration unlocs all the other joints and then it's drip - drip - drip again!
I'm even thinking an extra support plate and JBweld next!

 

[BlueRider]

After reading your expanation for why you want a chain brake I can understand your reasons, particularly since you have the remote mount triger and it could easily get bumped while moving the mill while it is running.

The heat issue is not an easy one. I ended up mounting the mill with an extra inch of bar between the end of the dogs and the mill when I run my 038. It helped but not enough in my opinion and you won't have that option. This is just one more little detail of why I think the 075 is actualy the perfect milling saw. If you are not running stihl HP Ultra you may wat top try a tank or two with it. it is a true low smoke oile and because it is vegitable based smells more like you are cooking than runnig a small engine. Not exactly plesant but not nearly so objectionable when you get a face full of exhaust. I still wear a respirator when there is no wind.

For sealing your oil tank you might try CA glue. it is chemical resistant and is reversable with heat.

 

[BobL]

After reading your expanation for why you want a chain brake I can understand your reasons, particularly since you have the remote mount triger and it could easily get bumped while moving the mill while it is running.

Yep that is an issue. When I first fitted the remote trigger I had it on the mill frame and the cable adjustment set firm and just picking the running mill up put tension on the cable and would start the chain going around. Even with the remote on the wrap handle I have to be conscious of the now shorter cable but if that gets hooked up on something while the engine is running the chain can take off.

The heat issue is not an easy one. I ended up mounting the mill with an extra inch of bar between the end of the dogs and the mill when I run my 038. It helped but not enough in my opinion and you won't have that option. This is just one more little detail of why I think the 075 is actualy the perfect milling saw.

I don't know about perfect, not being able to refuel while it's on its side is a bit of a pain. Then there are the small things like inboard sprocket but I agree they are great saw. I'm not going to be selling off the 076 as it will be a great back up saw to the 880.

If you are not running stihl HP Ultra you may wat top try a tank or two with it. it is a true low smoke oile and because it is vegitable based smells more like you are cooking than runnig a small engine. Not exactly plesant but not nearly so objectionable when you get a face full of exhaust. I still wear a respirator when there is no wind.

I'm lucky that where I mill is usually at least breezy, especially in the afternoons. I'll try the ultra and see how I go. I have a battery powered Triton respirator that incorporates a helmet, muffs and a face shield but have only felt the need to use it a couple of times

For sealing your oil tank you might try CA glue. it is chemical resistant and is reversable with heat.

Thanks for that info.

I turned down the white wheel on the mill and added that additional mount hole on the BIL mill last night. The chain brake now activates and the power head is very firm on the mill. The 880 sits firmer than the 076 which had a much smaller adapter plate and so the powerhead could rock slightly from side to side. To get around this with the 076 I had to add another connect bolt between saw and mill frame so I used the brake handle mount point on the top of the saw.

Next I have to make a sprocket cover of some sort

 

[DRB]

Bob you have mounted your saw in a similar way to how I mounted my 088 to my stationary carriage mill with an adapter plate in place of the cover. I find that this also stiffens the bar so it does not flex as much with weight of the engine hanging off the mill.

I have yet to build a sprocket chain cover. I kind of like how the sawdust is thrown straight back away from were I walk beside the carriage instead of piling up right were I walk. Maybe some kind of chain catcher is in order instead?

 

[BobL]

Bob you have mounted your saw in a similar way to how I mounted my 088 to my stationary carriage mill with an adapter plate in place of the cover. I find that this also stiffens the bar so it does not flex as much with weight of the engine hanging off the mill.

I don't have a problem with bar flex resulting from the weight of the powerhead, as my powerhead is mounted direct to the mill at the bar bolts. What I'm hoping is the longeradapter plate will reduce bar sag on my longer (60") bar. What size bar do you use?

I have yet to build a sprocket chain cover. I kind of like how the sawdust is thrown straight back away from were I walk beside the carriage instead of piling up right were I walk. Maybe some kind of chain catcher is in order instead?

Yeah the cover I made for the 076 drops the sawdust straight at my feet. With the 3120 it shoots the sawdust out further sideways, about 6 - 12" more away from the log, meaning I was not walking on the sawdust.

For the 880 I plan to make a stubby cover to shoot the sawdust out more like the Husky than the 076.

Cheers
Bob

 

[BIG JAKE]

Nice thread Bob. On the 076 cover plate and the sawdust issue you could have utilized the existing case as the throw chute. In other words, just mount the plexiglass to the bolt hole in the case to upper left of sprocket cover. You'd have to cut the bottom half of your cover mount off but you get the idea. If you're worried about strength to prevent something coming out sideways at you, you could extend a bracket outside the saw case and maintain the chute angle. It might not make enough difference in where the sawdust gets thrown to walk across the street over, but then again it might. Just a thought. Nice work

 

[DRB]

I only have a 36" bar on my 088. I am not sure how this plate will help for sag on a 60" bar? I have to opposite problem the weight of the power head makes the bar bow up. When I changed the mounting to a plate set up it did seem to help with this. When I bought my mill and saw it was not really set up how I would have built it but it was to good a deal for me to pass up. If I had of designed it I would have mounted the power head to the adjuster instead of to the bar to the adjuster. I will have to live with its limitations for now. The deal did get me a 088 thou.

Looking forward to seeing your cover design

 

[BobL]

Here are some simplified views of the saws and part of the mill, looking at it from the operators side.

The mill is the dark grey, the adapter plates are the light blue.

The top diagram is the saw alone

The middle diagram is how the 076 is arranged on the BIL mill. (I know it doesn't look like an 076 but it's purely representational) The 076 power head is shorter than the 088 and so the 076 can sit closer to the mill uprights. The inherent design of this mill prevents upward bowing and suppresses sag, even for 42" bars and even though the adapter adapter plate is short. However, for a 60" bar I get 0.09" sag at the 42" mark of the bar - NB: the greatest sag is not at the mid point (30") but 12" further out indicating the adapter plate and mill design are proving some support

The lower diagram shows the 088. The body is longer so it sits further away from the mill. To accommodate this a longer adapter plate is used. The position of the power head now acts more like a counter weight to the bar and will tend to lift the bar in the middle. In addition the adapted plate is longer providing even more support. I don't known what this transfers to in terms of sag because I have not tried it with my 60" bars yet!

I have to opposite problem the weight of the power head makes the bar bow up.

Yep - this is an advantage of the mill mounting to the bar method for longer bars. I heard the bar levels out when the bar reaches about 52" and stays fairly straight until 60" and after that the bar sags

When I changed the mounting to a plate set up it did seem to help with this.
When I bought my mill and saw it was not really set up how I would have built it but it was to good a deal for me to pass up. If I had of designed it I would have mounted the power head to the adjuster instead of to the bar to the adjuster. I will have to live with its limitations for now. The deal did get me a 088 thou.

A very good reason to do it!

Looking forward to seeing your cover design

I've look at what AggieWoodbutcher did and it will probably be similar or a half version thereof.

Currently I am still mucking about with the 088 adapted plate.

 

[BobL]

Nice thread Bob. On the 076 cover plate and the sawdust issue you could have utilized the existing case as the throw chute. In other words, just mount the plexiglass to the bolt hole in the case to upper left of sprocket cover. You'd have to cut the bottom half of your cover mount off but you get the idea. If you're worried about strength to prevent something coming out sideways at you, you could extend a bracket outside the saw case and maintain the chute angle. It might not make enough difference in where the sawdust gets thrown to walk across the street over, but then again it might. Just a thought. Nice work

Cheers BJ. My current 076 clutch and brake cover attach to the saw using threaded holes in the 076 saw body that are just not there on the 088 so I will need a new design. I really just want a deflector more than a cover - something like aggie wood butcher has but I want to be able to remove the chain without removing the saw from the mill which is what I can do on the 076.

 

[BobL]

880 BIL mill throttle

The first BIL mill remote throttle looked like this


Then it looked like this


Now, following a kernel dropped by Woodshop it looks like this!


Yep - it's a motorcycle throttle complete with remote kill switch and a throttle lock.

Yes the red grip clashes violently with Stihl orange but I think that is a good thing - it says watch out!

What I wanted was something that was not completely permanent because there would be occasions when I might wish to remove the remote throttle and use the 880 as a regular saw.

The throttle cost $20 from a MC wrecker. Finding a suitable linking point on the 880 proved very tricky and I tried many different combinations. Essentially all the exposed and accessible actions are "push" whereas cables need a "pull" and these are all blocked by the airfilter/carby housing and I did not really want to mangle a lot of plastic to get this working. Finally after staring and fiddling for hours I located a point under/above the trigger.

To access this point I had to get inside the top of the trigger. I unscrewed the trigger cover on the handle unclipped the top trigger linkage, and cut a small slit with a hacksaw and drilled a hole at the top of the trigger so the cable an lug can sit so.



The cable follows the pathway show to the ally bracket which supports the main cable adjustment as show. The bracket is held in place by a 3 mm allen bolt that passes through the housing and has a nyloc on the other side.


The regular trigger is still very accessible

Here is the cable bracket in better lighting. The cable passes thru a grommeted hole in the handle underneath the saw and over to the handle/


Here you can see the remote kill switch wiring which utilizes a small audio plug and connects in parallel with the kill switch inside the airfilter/carby area. The mini audio plug was used so that the remote throttle could easily be removed if required.

 

[BobL]

Remote throttle part 2

Another top view.


The knurled brass knob is the throttle lock. I made a small brass block with a 5 mm threaded hole that sits in a convenient recess inside the throttle and drilled a hole in the alloy throttle housing so that the threaded hole could be accessed externally . The throttle lock is basically a 5mm screw that passes thru the ally housing and threads into the brass block and bites into the throttle holding it in place. I will probably replace the knob with a lever although the knob is quite easy to use as the throttle setting can be held with the palm heel while the fingers lock the throttle.


The action is very short - about 1/8 turn to go WOT. The wrist action is also reversed from a MC - one has to roll the wrist forward. I thought it might be awkward especially as I have ridden a MC for many years. However, being the left hand it feels quite natural.

The kill switch is conveniently located and accessible - better than haveing to reach down and fumble for the switch near the regular trigger.


And here is the whole mill shot.


Thanks for the idea Woodshop!

Next - the clutch cover.

Cheers

 

[catman963]

Wow!! That is awesome!! Very nice setup there!!

 

[Rockfarmer]

That is really cool Bob !!