The BIL Mill Upgrade

BobL · Oct 20, 2008

Thought I start a WIP thread about the BIL Mill upgrade.

Here's some of the bits in comparison to the current mill.

The new rails are 65" (Can fit up to a 64" Bar) compared to 53" (52" bar)
The new bar is 60" compared to current 42"
Another cross bar will also be added between the rails.
The white rectangular strips are UHMWPE strips which are screwed to the bottom of the rails to act as skids.

There's not much more to it although I do plan to add an anti-bar-sag gizmo.

Here's a shot from another viewpoint.

Cheers

woodshop · Oct 20, 2008

Bob how much slicker do you think the UHMWPE strips will make it? You don't think to slick? I've used some on jigs, and often I want at least SOME resistance, but that slick plastic is like ice on ice. For some applications it goes to easy. Let us know it does here.

BobL · Oct 20, 2008

The current BIL Mill has UHMWPE strips. Initially they are a bit slippery but once that hard shine wears off they not so bad. They are as much protective strips for the ally rails as they are to reduce sliding friction on the log rails.

irishcountry · Oct 21, 2008

As always great work!! I wished you designed the measurment gauge and locking mechinism on my GB mill!! thanks for the pics

BobL · Oct 26, 2008

Here is a bit more progress with the upgrade.

I have replaced the previous rails with longer rails and added an additional cross rail.

And added an extension to the top lengthwise ally tube handle. Adding an extension is easier than carrying a whole spare tube.

It was very simple to lengthen the mill and is something that could even be done on the job if the other bar, chain and ails are available. Takes about 10 minutes to switch between bar lengths.

Here is a comparison with the existing 42" bar.

As reported elsewhere the bar sag is significant, 0.09". In this photo I have place an old ally rail on top of the bar and the gap between the bar and the rail represents the sag.

I'm working on a BIL Mill grade antisag bar device. BIL has some wild ideas which we are working on.

I have posted a similar picture elsewhere but am adding it here for completeness.

The 60" bar is a roller nose where as BIL Mill 1 outboard clamp could only handle a solid nose. The clamp has been modified with a 1/4" tensile steel bolt thru the centre of the roller nose. The clamp has steel jaws with a slot cut in it that the head and nut of the nose bolt can slide in when adjusting the chain. When complete the clamp locks the nose bolt and bar in place. I have modified all my bars to accept this arrangement.

Cutting length is 59.5"
Weight is 73 lb with a fully fueled and oiled 076.
Not exactly a light weight.

I'm not happy with the aux oiler delivery arrangement so I'm working on that at the moment.

Cheers

woodshop · Oct 26, 2008

WOW... cheers indeed. What a monster. You need to patent that thing before somebody runs with your great ideas. Yeah 73lbs is a little on the heavy side to be hefting around, but considering what it can produce, not bad at all. This is not a saw you will be using to make 1x6's. For what it does, it's really not as heavy as one might expect.

Seems as we get more an more into this we really need several csm's to be really efficient. A monster like the above for really huge slabs for solid wide natural edge table for example, and then a medium sized mill for most general work... and for smaller 8-12" dia softwoods, a small mill with a 60cc saw is plenty and would be light enough to swing around all day long.

Great pics Bob... thanks. I'm interested in that "BIL Mill grade anti sag bar device" you mentioned to solve that .09 sag. Seems like an impossible task.

DRB · Oct 26, 2008

Nice fab work BobL. I always enjoy reading your posts. Can't wait to see the saw dust fly. :chainsaw:

BobL · Oct 26, 2008

Cheers guys. Yeah it is a bit of a monster. In most situations I will be using this one with a helper. Not only because of the mill but also because of the size of the slabs it will generate. Just getting such big slabs off the log and onto the loader will be difficult. I have two candidate logs in mind for the big mill but it will be some time before I get to them.

After I finish making the anti sag device I will return to the 42" rails but install a new 42" sprocket bar, and new sprocket and chains.

BobL · Oct 27, 2008

Well I said BIL was working on a different antisagging bar devices and here is prototype A - of plan 3.

The idea is to use something to stop a long CS bar from sagging as the cut is started- once the bar is half way into the cut the bar will stay level and the antisagging device can be removed. The typical thing used is a wooden or plastic hook or lever that can be removed easily. The awkwardness comes in that a fixed length hook only works for one slab thickness and one needs a variable length hook for the different slab thicknesses.

Here is the gismo.

It's basically a magnet attached to the end of a bit of allthread which is bolted to the mill cross rail.

The magnet is from an old hard drive so it is incredibly strong. I just drilled a couple of holes in the supporting steel surround and bolted it to a piece of square ally tube.

Here the magnet is lifted well above the bar and shows the biggest gap between the bar and a straight bit of ally laying on top of the bar. The gap is 0.09". Interestingly the max gap not in the middle of the bar, its closer to the nose of the bar as the bar bolts help hold the inboard section of the bar level.
Here magnet is attached and wingnuts are adjusted to remove the gap.

The magnet is strong enough to bend the bar out of shape upwards by nearly half an inch before it gives way

By turning the wing nuts on the all thread the height of the magnet can be adjusted to accommodate different bar heights ie different slab widths.

Of course the proof will be in the actual cutting. A couple of refinements will be needed, one is a quick release mechanism to remove the antisag device once the bar has established the level cut.

BobL · Oct 28, 2008

I picked up a selection of rare earth magnets at work today to see if I could do better than what I already had. The system I had for testing them was a nylon cord attached to the magnet at one end - thru a pulley and attached to a bucket at the other end. I fixed the pulley to the roof above my vice and attached the magnet to the vice and then added tools to the bucket. The best magnets were my original hard drive magnet and a 1" magnet both of which would support ~35 lb before letting go. I also used the same system to measure I need 5.5 lb of of upward force to remove the gap so I figure there is plenty of force left over as a holding force.

Next I decided to make a quick release mechanism to the antisag device.
Close up of brass locking rings.

4 turns of the top ring and 1-2 of the bottom and the magnet can just be levered away. Not, I suppose super quick, but good enough for a trial run.

Next a re-jig of the aux oiler.

Cheers

irishcountry · Oct 28, 2008

Sweet post!! As soon as you said anti-sag thats what I was thinking would be slick too magnets hope it works out I found a website a long time ago think if you search for herbach&rademan you should find it they have lots of surplus motors magnets and other stuff for people who tinker might be worth a look for some magnets. I forgot whats stronger rare earth or man made but they have a show here in the US called mythbusters they got ahold of some monster magnets that had tons of pull and I thought at one time I seen them as a surplus Item on that site I mentioned. Anyway your a tinkerer/inventive type might want to check it out!! Hope it comes in handy again great work thinking out of box! Thanks for the pics take care irishcountry

820wards · Oct 29, 2008

BobL said:
I picked up a selection of rare earth magnets at work today to see if I could do better than what I already had. The system I had for testing them was a nylon cord attached to the magnet at one end - thru a pulley and attached to a bucket at the other end. I fixed the pulley to the roof above my vice and attached the magnet to the vice and then added tools to the bucket. The best magnets were my original hard drive magnet and a 1" magnet both of which would support ~35 lb before letting go. I also used the same system to measure I need 5.5 lb of of upward force to remove the gap so I figure there is plenty of force left over as a holding force.

Bob,

Magnets from the back of microwave tubes are very strong too, and they have a hole in the center. I epoxy them to the back side of tuna fish cans and use them for putting screw/bolts in so I don't loose them. You darn near have to pry them off. That would also work for keeping those long milling bars from sagging. Just find a guy who repairs appliances and he'll probably have a bunch of them stuck to the walls of his repair truck.

jerry-

woodshop · Oct 29, 2008

Interesting... great post Bob. My thoughts seem to follow yours... as soon as I saw how you were doing this my mind started trying to figure out a quick release mechanism for that thing. Ya know, since it is only really pulling UP on that long bar, why does it need a brass nut or anything for that matter on the underside of where the threaded rod is positioned up top? Why wouldn't it be kinda just held there in place by the bar/magnet trying it pull it downward? Then if you design some sort of rocking mechanism down at the magnet part you could just pull on that upper threaded rod and thus "rock" that strong magnet off its position on the rod once you bury the bar halfway, barely losing a step.

Strong magnets... got one from an ancient huge floorstanding 100MB (enormous capacity in those days) hard drive that was about the size of a modern dishwasher. This three pound magnet was so strong that when I put it on my metal surfaces in the shop the ONLY way to get it off was to slide it over partially off the edge before you could pry it off.

BobL · Oct 29, 2008

woodshop said:
Interesting... great post Bob. My thoughts seem to follow yours... as soon as I saw how you were doing this my mind started trying to figure out a quick release mechanism for that thing. Ya know, since it is only really pulling UP on that long bar, why does it need a brass nut or anything for that matter on the underside of where the threaded rod is positioned up top? Why wouldn't it be kinda just held there in place by the bar/magnet trying it pull it downward?

Thanks WS - yeah I had though a drop fit would suffice as well. But after my experience with the Aux Oiler tank cap (a chunky brass screw cap) which came loose and fell on the chain and was flung into my face, everything on the mill gets locked down. I can just imagine the anti sag device some how being knocked (eg I forget its there and it falls on the chain!!!) BTW the aux oiler cap is now plastic!

Then if you design some sort of rocking mechanism down at the magnet part you could just pull on that upper threaded rod and thus "rock" that strong magnet off its position on the rod once you bury the bar halfway, barely losing a step.

To remove the magnet I drop the bottom screw half an inch and just keep turning the top screw. With the bar held in the kerf , turning the top screw easily breaks the mag bond. Then I just lift the gizmo out. I'm going to fit a bracket so it can the screw onto the mill above the rails so it's always readily available

Strong magnets... got one from an ancient huge floorstanding 100MB (enormous capacity in those days) hard drive that was about the size of a modern dishwasher. This three pound magnet was so strong that when I put it on my metal surfaces in the shop the ONLY way to get it off was to slide it over partially off the edge before you could pry it off.

We have some really serious magnets at work in our mass spectrometer. The biggest weights 6 tons, draws 70 A and is water cooled. When operating it is recommended people stay 3 ft away from in or it can do some serious damage to anyone holding a piece of magnetic material eg it will drive a steel tool into your hand if it happens to get in between the magnet and hand. The funniest thing is key rings spontaneously trying to get out through pockets.

woodshop · Oct 29, 2008

BobL said:
Thanks WS - yeah I had though a drop fit would suffice as well. But after my experience with the Aux Oiler tank cap (a chunky brass screw cap) which came loose and fell on the chain and was flung into my face, everything on the mill gets locked down. I can just imagine the anti sag device some how being knocked (eg I forget its there and it falls on the chain!!!) .

Makes sense... yeah kinda forgot you have a moving chain there going on... sheeeeesh. With something that vibrates as much as a csm, anything that CAN move or fall in a certain direction eventually will at some point.

BobL · Oct 29, 2008

Thanks for the tip Jerry.

What's happening to your mill?

820wards said:
BobL said:

Magnets from the back of microwave tubes are very strong too, and they have a hole in the center. I epoxy them to the back side of tuna fish cans and use them for putting screw/bolts in so I don't loose them. You darn near have to pry them off. That would also work for keeping those long milling bars from sagging. Just find a guy who repairs appliances and he'll probably have a bunch of them stuck to the walls of his repair truck.

jerry-

Click to expand...

820wards · Oct 30, 2008

BobL said:
Thanks for the tip Jerry.

What's happening to your mill?

Hi Bob,

Since retiring last September I have been in the remodel mode on the house. I hurt my shoulder a couple of months back so that really set me back. As for the mill I just picked up a throttle cable that will work quite well. I used a bicycle brake handle for the throttle, something similar to yours. After that I only need to plumb the oil lines for the bar and make my exhaust pipe. Seems like I would have plenty of time to do these few things to get started milling, but it's just not happening yet. I also play drums in a band and we have been rehearsing and playing a lot of gigs that has occupied much of my time. I promise I will get back to the mill.

You have been doing a great job on your mill and with a 52" bar, wow, you must have some pretty big trees there down under.

jerry-

BobL · Oct 30, 2008

820wards said:
Since retiring last September I have been in the remodel mode on the house. I hurt my shoulder a couple of months back so that really set me back. As for the mill I just picked up a throttle cable that will work quite well. I used a bicycle brake handle for the throttle, something similar to yours. After that I only need to plumb the oil lines for the bar and make my exhaust pipe. Seems like I would have plenty of time to do these few things to get started milling, but it's just not happening yet. I also play drums in a band and we have been rehearsing and playing a lot of gigs that has occupied much of my time. I promise I will get back to the mill.

Sounds like a busy life - better than the other way around I reckon. I too have sore shoulders (bursitis). Doctor says I shouldn't be doing any heavy lifting at all but I notice I feel better after a day with the mill so I keep going back for more.

You have been doing a great job on your mill and with a 52" bar, wow, you must have some pretty big trees there down under.

It's a 60" bar (it's actually a bit longer that that) with 59" of cut - that nose holding system I worked really does wonders for cutting length.

Re: big trees. I'll still be mainly using the 42" bar to cut most stuff. I have 2 logs that will need the longer bar but hope to eventually get hold of some more.

Anyway looking forward to seeing your finished mill sometime.

BobL · Oct 30, 2008

remote aux oil control

This is no biggie even though it has taken me several evenings to sort out.

When stopping midway along a slab, eg to refuel, I can't just reach across the log to turn the aux oil off so I have to walk around the long.

This is because my aux oil talk is down low and the taps are underneath it like this.

With a longer bar the problem is only going to get get worse.

What often happens is the walk around the log to turn off the oiler becomes a PITA so I often just let it drip while I make a quick adjustment, then I forget it's on and I get distracted doing something else and before long half the aux oil tank has emptied itself onto the ground. Here is my solution.

Old bike gear change lever.

Connect cable to modified tap and spring mechanism.

Even though I have a needle valve installed for fine flow control the click gear lever also seems to provide reasonably reproducible flow control as well!

BobL · Nov 3, 2008

Medium BIL mill was able to be moved around easily on a sack trolley like this.

But with the new rails on BIL Mill 2, the trolley is too small. I was going to extend this trolley or make a new one but as I like to lift the whole mill and trolley into my van as one, BIL Mill 2 plus trolley was just getting too heavy so here is my solution.

The wheels are from the old trolley and are bolted onto the ends of the rails. Net effect is the new mill plus wheels is lighter than the old mill plus trolley.
Funny dog leg axle mounts are so I can use the same axle as on the trolley.

What colour should I paint it?

Cheers

The BIL Mill Upgrade

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