krtwood Posted June 17, 2014 Posted June 17, 2014 Working on making a woodworking band saw and I want to use the 75mm motorcycle wheels and chain for the blade. My problem is that the chain can't ride on the bare wheel because of the pin connections inside the rim. Band saws, at least smaller ones, do have rubber "tires" but they are really thin so not really visible. I'm hoping to find some other solution besides using the 88516 94.2mm racing tires. The x1681 tread looks like it could possiblly work better but i have no idea if it would fit on the wheels or how wide it is. The other treads don't seem to have a smooth side that could work. I'd be open to other ideas. I'm not ruling out using something non lego but if I can find something that works all the better. I think it would be a cool B model for a motorcycle set as there's not much else you can do with a motorcycle besides another motorcycle, but it needs about twice as much chain as a motorcycle would use. I also have to figure out what to do with the upper blade guides which need to move up and down. Larger saws may have a rack and pinion here but smaller ones just have the post slide through a hole and held in place by a screw. My non elegant solution is to just pull the pin holding a lift arm and put it back in after you move it if I can't come up with a really compact rack and pinion that doesn't have too much play that can move about 6L. Functions: Blade spins Blade tension Upper guides up/down Table tilts Doors on wheels and base Quote
Tommy Styrvoky Posted June 17, 2014 Posted June 17, 2014 (edited) Couldn't you just have the blade tensioned on the upper wheel and have the upper and lower guides on the table keep the blade forced on the edge (not the center) of the wheels. Edited June 17, 2014 by Tommy Styrvoky Quote
krtwood Posted June 17, 2014 Author Posted June 17, 2014 Couldn't you just have the blade tensioned on the upper wheel and have the upper and lower guides on the table keep the blade forced on the edge (not the center) of the wheels. It won't ride in the center no matter what. For lack of better terminology, I'm going to refer to outer and inner rims and the tire normally seats in between the two on each side. The chain is too wide to fit between the inner rims but too narrow to sit on top of them very well either because the sides of the chain are very thin. It would ride straddling the inner rim well, and the edge of the chain would be in the center of the wheel which is where it's supposed to be, if it weren't for the pin connections. The only part of the rim that is round all the way around the wheel is the outer rim, so the chain would have to be straddling the outer rim which would make half of it hanging off the edge of the wheel which isn't acceptable. Even if I find something that can wrap around the wheel I will probably have to find something to shim where the flat pin connections are to keep the chain from vibrating. The other possibility might be rubber bands in between the inner and outer rim that might build up enough of a flat area for it to ride on at the edge of the wheel, but I kind of doubt that would work and I don't have any official rubber bands to try it with. Quote
OzShan Posted June 18, 2014 Posted June 18, 2014 Got any rims from the classic technic "shock cycle" 8838? Pretty sure they are just smooth all the way round. http://lego.wikia.com/wiki/8838_Shock_Cycle Quote
krtwood Posted June 18, 2014 Author Posted June 18, 2014 Thank you for the suggestion, that would work on a little bit smaller scale. I make woodworking videos and am doing one very soon that is lego related so I thought it would be fun to have at least one lego tool and pretend it actually cuts wood. So I need a very specific capacity that it could theoretically cut and I am already pushing it on the proportions with these wheels. I got the upper section mostly worked out. There is a little more play in the wheel than I would like but I think it will work. There is very little clearance around the wheel so I think I'm going to end up just wrapping it in some thin cardboard, at least for the time being. Hey, cardboard from a lego box is an official lego part, right? ;) Quote
krtwood Posted July 14, 2014 Author Posted July 14, 2014 Here is the "finished" version, and by finished I mean where I ran out of parts and money :) I had to add a quick and dirty tracking adjustment to get the chain to stay on the wheels, basically just pushing the far end of the upper axle up. The chain would run without the cardboard around the wheels but it was vibrating all over the place. There wasn't room to use the same blade guide as above the table under it, without moving the table up another unit, so I used one end of a U joint instead. You can't really see that in the pictures. The table does tilt and locks in place at 90 degrees, though with the amount that the frame flexes under tension you have to tilt the table about 5 degrees to get it perpendicular to the chain. The fence can move and be adjusted for blade drift, which is basically the tendency of the blade to cut at a slight angle. Quote
Lundgren Posted July 14, 2014 Posted July 14, 2014 Wow I like this one ALOT! As a metal fabricator I have myself a Mössner bandsaw and this reminds me of it! :D Quote
grum64 Posted July 14, 2014 Posted July 14, 2014 Excellent build. You've got it spot on. Very nice to see something different to the plethora of, albeit brilliant, vehicles Quote
Eraman Posted July 16, 2014 Posted July 16, 2014 It is great. In hungary we sharpen wood-industry tools like bandsaw, so we know these machines and it looks like the real one Quote
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