How to stiffen up a bandsaw

[muddstopper]

Well I'm stumped. I made a test cut and it was so square it was hard to catch a fingernail on the difference between the two ends. So, I decided to make a cut for a piece I needed for the project. No good, just as bad as ever. No two cuts the same. Through messing with it for today. I have about 8- 2.5in holes to drill and my drill only goes down to 250rpms. Did a test hole in a piece of scrap because I was afraid I couldnt drill it. About 15mins to cut thru, after drilling a clearance hole for the chips to fall thru. That will give me something to do while I wait on the bird to get ready for eating tomorrow.

I'll look at the roller guides later, I noticed that sliding them in and out, there seems to be a lot of slop. The back guide, (closest to the motor) doesnt have any adjustment, and it seems pretty far away from the cut piece. Might have to be back that far to clear the chips???, The other guide, I dont know, thats a long way to slide it and expect it to stay true. Metal arm is pretty flimsy. I might be able to take it off and give it a good cleaning, tighten everything back up and it be ok. Maybe add a shim or something. Enough aggravation for one day, will look at it tomorrow.

 

[BukitCase]

"Shiny enough to pass the buckit test?"

No way - straight enough, but a ways to go on "shiny"...

(You'll have to forgive the front edge of the brush bucket frame, I wasn't done yet )

On my HF saw, the roller guide castings are a bit rough but seem to stay pretty square front to back - I tend to leave the rear one set, and the front one as much as possible. I also check with a small machinist square whenever I move 'em - a 4" or 6" clamped in the vise works well for that (nearly touching the blade, look for differences in square to blade distance)

Blade roller bearings - on both of mine, one is on a lock-nutted eccentric insert, I keep 'em just loose enough to (barely) get a new blade between them, helps minimise wander. (Thinking this may be one of your problems)

My misgivings on those sliding guides is the main reason I try NOT to move them unnecessarily, and if I do the machinist squares come out afterward.

Vertical squareness can kinda be "eyeballed", but the only sure way to know is test cuts. If you can't repeat results, it almost HAS to be too much slop somewhere... Steve

 

[muddstopper]

Steve, after reading what you said about the roller guide, I put my coat back on and went back to the shop. with just a little bit of effort, I could wiggle the guide, so I decided to take if off and look at it. The guide was pretty rusty and for some reason, the aluminum guide it slid thru had washers between the block and the frame. With the washers removed, the guide bar still slid thru it easily and I could still wiggle the bar. The aluminum block didnt seem to have much wear, but the guide rod still seemed to loose to suit me. I cleaned all the rust off the bar and gave it a shot of paint. I figure the paint will help keep it from rusting again and might take a little slop out of the assembly. When it dries, I'll put it back together sometime tomorrow. Got it setting beside the wood stove, baking the paint on. The rollers all seem tight, bearing good. The assembly the bearing bolt to is cast, so no flexing there. If this dont do it, all I can think of is the beam is just to flimsy. Its just thin rectangle tube with thin flat plate welded on to hold the band wheels. I could plate it to stiffen it up some, but that would probably make the arm to heavy. Heres a few pics of the guide assemble and the one cut that was almost perfectly square, you can just barely see the edge of the steel under the square. Plus one more wedge, the byproduct of trying to get everything square.

 

[BukitCase]

Those washers look to me like a "SEP" - I bought one of those about a month ago (Stands for Somebody Else's Problem) - IOW, looks like somebody tried to fix that problem and when it didn't help, you bought it

I did the same with a HF saw (the 4x6) on CL for $100, had a beefier stand and chip tray with small coolant pump. I have my other small saw in a "phone booth" at the house (8x10 foot add-on) so there's not enough room to cut 20 foot steel down unless you want all the pieces less than about 3 feet long - I figured I could put "off road" wheels on the second saw so it was portable, and use it either for long stuff and/or 45* cuts so I'd save time compared to resetting one saw back and forth.

The saw didn't cut anywhere close to straight when I looked at it, but I thought it just wasn't set up right. Long story just a bit longer - after fiddling with it for a couple hours, I found that the saw casting (wheels and blade and motor one) was WARPED

So now I have a "parts saw", and a heavier stand with chip tray. Ended up buying a NEW 4x6 HF saw on sale, when I get time to assemble it it'll be on the heavier stand/offroad wheels, etc...

My point (if there IS one) - If I were you, I'd use some of the methods I listed in post # 19 for now, and start a "kitty" for a different saw. At least now, you know a bunch more things NOT to ignore when looking for one - including the one that bit ME in the *** - a warped casting. 'bout the only way to avoid THAT one is take a couple pieces of scrap with you and MAKE them show you it can cut straight... Steve

 

[muddstopper]

Those washers look to me like a "SEP" - I bought one of those about a month ago (Stands for Somebody Else's Problem) - IOW, looks like somebody tried to fix that problem and when it didn't help, you bought it

Well I'm not so sure those washers arent part of the original design. They do extend toward middle some to hold the slide bar, but I cant see where they are necessary. The bar is thinner than the slot in the aluminum block. I aint ready to give up on it just yet. I can remake that aluminum block, make it a tad longer and tighten up the clearances. I aint got time to fool with right it now, and I'm done cutting the 8in plate, so I'll put it back together and fiddle with later. I actually think just that thin layer of paint will take out most of the slop in the guide bar. That and working on leveling out the bed, which I think is the biggest problem. If you put a straight piece of steel on the bed and it rocks, I dont think you can adjust the blade enough to get a straight cut. I think the little heating and prying on the bed helped, some, Not exactly sure how i will get it perfect. It will take some time I'm sure, but short of cutting the bed out and replacing with something heavier, it probably aint going to happen. I do have a piece of 6x8 thick wall tube that would probably work, if I decide to give it a try. The saw cuts true enough on smaller metal so I'll live with it for now. I'll make another cut tomorrow just to see how it does (I need another wedge LOL),and then roll it back in the corner.

 

[muddstopper]

Well, fiddle stiks. I put the guides back on the saw and decided to make a test cut. Thought I had everything close to being right. Saw actually cut square enough, edge to edge, but now the cut has a bow in it. I suspect feed rate as the cause. I have noticed the saw sort of drops and stops, drops and stops when its not in a piece of metal. I dont like that little gate valve that controls the speed on the little cylinder. Cant never get it adjusted the same way twice. Just wondering what kind of oil everybody has in their feed cylinder. I thought about just trying some regular motor oil or maybe some jack oil. Maybe even dextron, or should I be trying to go thicker oil instead of thin?

 

[rswyan]

Thinner rather than thicker IMHO ...

 

[aczlan]

I dont like that little gate valve that controls the speed on the little cylinder. Cant never get it adjusted the same way twice.

Might try a needle valve?

Aaron Z

 

[BukitCase]

My Jet has a "calibrated" (multi-turn, labeled 0-10) needle AND an on-off (ball valve), but the ball valve does NOT bypass the needle, it only BLOCKS it - so you can't set a slower feed speed, then "bypass" to get the saw down ready to cut quicker. Both appear to be integrated such that it'd be a pain to change, but I'd prefer a parallel "bypass" added - that's on the list at #842 at the moment

Still, at least the needle is very repeatable - it drops at the same rate every time I set it on "6", for example.

Maybe your saw has extra "goodies" in the oil that act as a "variable check valve", I've had that happen to me on a couple different pieces of gear.

It's enough to drive me crazy, but I know the wife would just accuse me of being lazy "'cause I'd only have to back up a few steps to get there" :laughing:...Steve

Yours might benefit from a flush and refill - if you do, I'd keep what comes out and try to get close to the same viscosity...

 

[muddstopper]

Actually, it has the needle valve. I plan a oil change to see if that helps. I just read a very long thread on the shoptalk forum about a carolina rebuild. The fellow bought a very used carolina similar to what I have and completely rebuilt it. Didnt like it and sold it to another member, who tinkered with it some more. Added more hp, went from 3/4hp to 1hp motor, bought some new, thinner, variable tooth blades and swears it works good. He also flipped the hydraulic cyl upside down and filled it with 90wt gear oil and claimed it helped the feed. My saw already has the 1hp motor, so I guess I will flip the cylinder and refill with 90wt and see how that works. I still think thinner oil would be better, but??? I have a ideal to stiffen up the bed by wrapping the underside with some metal and welding gussets to the top of the tray under the bed. All this needs to take a back seat for now as I have a bigger project being ignored.