Chainsaw powered mini bandmill

[Brmorgan]

Has anyone ever built one of these? I know I saw pictures of a retail one once but I can't remember what it was called. Anyway, I recently came into a bit of 1/2" band stock and actually had this idea before I knew one existed. I have a couple of good 8" wheels to use.

I think this would be a kicka$$ machine. I'd still make cants with the Alaskan, but a mini bandmill capable of cutting, say, 12" wide would be so much faster to cut a bunch of 1" stock, or two-by, 6X6 beams... And it would be so much more efficient for kerf loss. Most bigger logs I cut, I lose two good boards to chain kerf.

The only real quandry I have is the best way to link the drive from the engine to the wheel shaft. I was thinking of welding an old clutch drum to the shaft, putting a sprocket on, and just using some old chain with the teeth filed off. But something tells me that a 10,000+ RPM band mill is a bad idea . I've seen big highspeed bandmills in the sawmill explode, and while the size is no comparison, I'm also not holding them in my hands. So I've been trying to figure out some sort of belt drive that wouldn't be require too much modification to the saw.

I could pretty much permanently dedicate either my 181SE (80cc) or my old Pioneer P41 (66cc, way more torque) full time to this setup, so I wouldn't really be worried about having to swap the engine off easily. What do you all think?

 

[dustytools]

They're called a Ripsaw. Woodshop and a few others here use them regularly. I think that they can be had new for around $1600.

 

[AndyR]

Yup-Ripsaw

I just got the used one I bought last fall up and running. I paid 1,300 with shipping for the ripsaw w/a really nice shape 036, 3 guide beams, and carriage unit (which I probably wont use for now).

I bought some new bearings and blades and a few spare knobs etc this past week. My unit was an older one and I opted to update it with a idler wheel tracking assembly (drill and tap one hole). Once set up , it seemed to track pretty well on it's own. I have yet to put it to work on any logs, but hope to in the next week or so. I have a big walnut and a black cherry scheduled to be removed in the next week or so.

More to answer your question, If you are good with fabrication and have the time and parts available, go for it. I think the tricky areas might be tracking and mounting the saw to the chainsaw powerhead.

I think the ripsaw blades I have might be closer to 3/4" wide...and about 3 tpi.

Andy

 

[AndyR]

The ripsaw uses a gear setup to reduce the rpms. Here's a not-so-great pic of how it's configured. It's a smaller gear that connects to the ring gear on the wheel.

 

[woodshop]

...More to answer your question, If you are good with fabrication and have the time and parts available, go for it. I think the tricky areas might be tracking and mounting the saw to the chainsaw powerhead...

I agree with Andy, most of the main structure can be fabricated IF you have a machine shop and are pretty handy with the tools in it. But the tough part would be the cast aluminum block that mates the Ripsaw to the powerhead. It has a hole going through it connecting the saw oiler output to the ring and pinion in the Ripsaw to lubricate it. Figuring out an elegant way to do that while the saw is bolted to the Ripsaw would be a tough one. I also agree that alignment would be a little tricky. In order for the Ripsaw to slice clean flat boards there has to be a good bit of tension on that blade, which if not checked and accounted for wants to twist that Ripsaw carriage and wheels out of shape. It has to be engineered such that it can take that much tension and keep that blade on track, as well a way to adjust above mentioned tension as the blade gets dull and as different species of wood demand it. Bottom line... sure it can be done, but there is a bit more to it than meets the eye, as is with many things. This has actually been discussed here in this forum before... do a search on Ripsaw and you'll find other discussion on building your own Ripsaw type mill.

 

[dancan]

Here's one for sale (not mine)
http://halifax.kijiji.ca/c-buy-and-sell-tools-equipment-RIPSAW-The-Portable-Mill-W0QQAdIdZ53328227

 

[Brmorgan]

The ripsaw uses a gear setup to reduce the rpms. Here's a not-so-great pic of how it's configured. It's a smaller gear that connects to the ring gear on the wheel.

Wow, that must be something like a 50:1 reduction. Don't think I'd need that if I used my old P41, I think it's only something like 7500 RPM anyway. I do have quite a few old small automatic transmission gears. So exactly how does the power transfer from the engine to the reducer gears? Do you have to take the clutch and everything off the crankshaft and put soemthing else on, or does it drive off the sprocket, or what?

I have no intention to buy one of these - my Alaskan does what I need and I just don't have the $$, and I plan to buy or build a fullsize bandmill in the near future whenever I find a suitable engine. It was just an idea I had, and I'm the type that would much rather build something and learn a bit at the same time than buy it, assuming it's within my realm of ability. Actually the idea came from looking at one of those little handheld electric bandsaws that a lot of plumbers and gasfitters seem to use. Materials and creativity I have in abundance, time not always so much. I have standing permission to take anything out of the scrap steel bins at the sawmill where I work, and the local steel supply sells short odd cutoffs for practically nothing. I just have a cheapo AC welder at home but it does most jobs OK, and anything it can't do I can take to work and use the big Miller for, or in the case that it's beyond my ability (aluminum for instance) the guy we contract our machining to will do small jobs under the table for a really good deal.

Andy, I wouldn't mind seeing a picture of that idler tension system if possible - I was thinking of using a small (1" dia. or so) idler wheel to tension the blade on the top return. I would still have the tail wheel movable to take up most of the tension and use the idler to make small adjustments. I would also build two 3-bearing tracking assemblies like those found on woodworking bandsaws and have them on the bottom, one on each side of the cant. Ideally I think the one on the side away from the engine should be movable to keep it as close to the cant as possible to prevent blade wandering, also like on woodworking saws. As for the wheels themselves, are they "toed in" (tilted) a bit like on a full-blown bandmill, or are they straight and only one adjusted slightly to track the blade?

Also, exactly what is the saw's oiler being used for on these? I know water or very lightweight oil is useful for cooling bandsaws but I've never heard of using chain oil. Or does it all go to oiling the reduction gears and/or wheel bearings? As for mounting the engine, I was just planning on using a piece of 3" X 1/2" steel bar stock or something similar and machining holes to fit the mount profile of the saw I decided to use. Then I could weld or braze a small hose fitting over the oiler hole and send the hose wherever the oil needed to go. It would be even easier to use a really old saw (like my Pioneer 1450, if I ever get it running) that has the visible external oiler lines - just disconnect or cut it and put the hose directly onto there.

Thanks for the help, and sorry for all the questions but all the safety guarding on these make most photos rather uninformative. Google isn't helping too much either except for a bit of info on the actual Ripsaw machines, not for building your own. I read one guy's experience somewhere on the internet and he said he was getting 1' of cut, 8" wide, in about 5 seconds with only a 60cc saw. Not sure what kind of wood, but that's about as fast as my 090 in 6" Pine, and would be much more fuel and waste efficient. I figure if I can make this work it'll make building a big bandmill a lot easier.

 

[scottr]

The gear ratio that the Ripsaw uses is 11:1. The bands are a special silicone steel to be used on the small 10" bandwheels. You might want to talk to some band experts about your 1/2" band stock for wheel recomendations. How many teeth per inch is this 1/2" band stock? The Ripsaw website has some good drawings for parts illustration.

 

[Brmorgan]

I have no idea what type of steel this band is, but I believe it's 1/2" 4tpi. It's only enough to make two, MAYBE three bands so it's not like I'd be saving a ton of money by using it. I do have a few dozen feet of 1-1/4" 1TPI band somewhere but it's used and a bit rusty and just a BIT too big . There is a shop in a city a few hours away that I've ordered good Silicon Steel bands for my woodworking saw from and I think they'll custom make other lengths too.

 

[scottr]

The last bands that I ordered were silicon steel from Hakansson Saw Blades from East Elgin, ILL. 3/4" .025" 3TPI . To answer your oiling question on the Ripsaw, the oiler is turned to the minimum setting because it is only used to oil the drive gears.

 

[AndyR]

Here's a pic of the idler tracking mechanism with a little bit of my scrawl along beside it. It's really a simple design. The drive wheel also has a tracking mechanism. It pushes the drive wheel in the same left right horizontal direction. It's just a threaded allen bolt w/set screw mounted in a block that is attached to the front cover of the drive side of the unit.

Sounds like you have a lot more experience with this kind of stuff than I do. Give it a little thought before you assemble it and I'm sure you'll be able to come up with something (maybe even better).

As others have mentioned I would give some serious thought to the bands you will need to use. This thing cranks at a pretty good pace and the ripsaw bands I bought seem pretty substantial.

And definitely do a search on this forum for ripsaw. It'll give you a good overview of how the thing works at least.

As a side note, the manufacturer contact person for the Ripsaw has been great to deal with. I sent an email with pics of my machine and got back a lot of helpful info and just plain good service. Something that makes me want to give them my return business.

Good luck and let us know how it goes.
Andy

 

[woodshop]

... So exactly how does the power transfer from the engine to the reducer gears? Do you have to take the clutch and everything off the crankshaft and put soemthing else on, or does it drive off the sprocket, or what?

The Ripsaw mates to the powerhead via a standard spur sprocket, which can be gotten at any saw shop or online from places like Baileys. One comes with the Ripsaw, which is why you need to tell them what kind of saw you will be using when you order.

One concern I would have with your idler wheel idea for tracking and tension, would be building something small and compact enough that wouldn't get in the way of the saw going down that log or cant. Weight would be another concern. The Ripsaw with a pro 60cc saw is about 50lbs, which is about max for me after swinging it around all day. Anything heavier would limit use for guys like me.

 

[scottr]

To add to what woodshop said, the drive hub has pins that mate the spur sprocket and the other side of the shaft has the sprocket that turns the large gear that is bolted to the drive wheel.

 

[Brmorgan]

To add to what woodshop said, the drive hub has pins that mate the spur sprocket and the other side of the shaft has the sprocket that turns the large gear that is bolted to the drive wheel.

So am I wrong in assuming that would require a Stihl with an inboard clutch?

 

[scottr]

You're not wrong, it does take a inboard clutch. Have you looked at the owners manual that you can download from the ripsaw.com website?