Thread: Band saw tension spring ??

Originally Posted by REALOldNick

No the drawing was what I thought, but I am starting to see it's maybe quite different. Sorry I have not believed you. My only excuse is that it's most unusual.

If so, as was said a long way back before all the fingertip skin was wasted yeah I cannot see why such a heavy spring.

Those drawings are rough as, BTW. I usually use Rhino, which cost a packet but for me was outstanding as the best of the lot for logic of use and power. I became a student and bought it that way. Being the honourable twerp that I am, I actually attended the classes

OK. Your OP said 950. Given that I reckon Hafco use the mm capacity as the capacity, I was beginning to wonder....

Can you scan and put up anything that shows the mechanism in any detail?

hmmm...senility and wives. Some...QUITE some time ago I bought a 2ndhand dust extractor. I took it to bits to bring home. Went to put it together and could not find the piece of tube from the blower to the bags. It's 125mmmdiameter and 800mm long....so not a wingnut Looked and looked. Rang the guy who sold it. He is a busy man, but a really nice guy. He looked and looked.....then one day SWMBO and I were walking through the carport and she says "Is that what you have been looking for?" and there it was, plain as day. I must have laid it aside when I brought the gear in. I must have walked past it....50? times........she has had the sense to treat my humiliation as enough and not dwell on it!

So I cannot mock.

OKOK. I will stop jabbing about the spring thing , but I am really still interested in how you set tension.

Don't know much about metal cutting BSs,but I do know the band is under HUGE tension and yes they may well not have a spring.

OK. Your OP said 950. Given that I reckon Hafco use the mm capacity as the capacity, I was beginning to wonder....

I don't understand this, is it the model No I gave you,,,which is 350, which I understand to be the cut size. which is preceded by BP. Wot is OP, Pliss?

The actual tension is set by turning the knob on top of the machine which turns the threaded rod, which has two size threads on it, one for the turning knob and the other for the "nut" section which drives the attached wheel and axle upwards (as a nut is wound upwards if the bolt is held thread down). This does depress the spring...

Please pay for the merry-go-round ride at the ticket office!!!!!

OP= Original Post

"I have a Habco BP 950 band saw and it became very hard to tension the blade,...."

OK. I understand the mechanism you describe (although it seems a strange way to go about the job: you are fighting a spring that effectively does nothing more than act as a lock nut), but is there a tension gauge on the saw? As I say, once the band takes up slack, the axle should move an unreadably small distance if there is no actual tension spring between the nut and the axle. If there is a great deal of movement once the blade slack is taken up,. there is something else in play. Tension occurs in the blade _because_ it stretches so little.

Originally Posted by REALOldNick

OP= Original Post

"I have a Habco BP 950 band saw and it became very hard to tension the blade,...."

OK. I understand the mechanism you describe (although it seems a strange way to go about the job: you are fighting a spring that effectively does nothing more than act as a lock nut), but is there a tension gauge on the saw? As I say, once the band takes up slack, the axle should move an unreadably small distance if there is no actual tension spring between the nut and the axle. If there is a great deal of movement once the blade slack is taken up,. there is something else in play. Tension occurs in the blade _because_ it stretches so little.

I think so too. IF there was no thread to the top where the tension bolt goes through the pressed steel covering to the tensioning knob, would a spring be necessary then?

Remember to tension, the top wheel is wound upwards lifting and tensioning the blade. At this pint the pressure is upon the item #5 under the knob, and at this stage this is all I can see as a possible 'bouncing' point that would need a spring.

We must admit, Nick, that our discussion is purely academic now as the BS works as is. However, I see that we share and inquiring mind complication, painful ain't it?

BB

Originally Posted by Black Bear

I think so too. IF there was no thread to the top where the tension bolt goes through the pressed steel covering to the tensioning knob, would a spring be necessary then?

If that was not threaded, unless the other end of the rod was held underneath, the whole thing would not tension at all. That is unless some other method was used to secure the rod at the top. Some have used ratchet methods etc.

Originally Posted by Black Bear

Remember to tension, the top wheel is wound upwards lifting and tensioning the blade. At this pint the pressure is upon the item #5 under the knob, and at this stage this is all I can see as a possible 'bouncing' point that would need a spring.

We must admit, Nick, that our discussion is purely academic now as the BS works as is. However, I see that we share and inquiring mind complication, painful ain't it?

BB

You are correct. That is where the spring goes in most models...between the "nut" and the axle/housing.

I actually found some other "350" models from different makers....well different sellers same factory probably . I was _still_ trying to make sure that the setup was correct as you described. It is.

But yeah wanting to delve can be a right pain, for others as well as me.

Moving right along.....This BS has 2 speeds, 300 and 1000 MPM Q: Would there be any use for the 1000MPM, or what are the uses for...?

BB

IMO the 1000 mpm (about 3200 fpm, which is the common benchmark still) is the _most_ useful...pretty much standard for wood. What is usually more important is the blade width and teeth per inch, when cutting different woods.

300..???? Maybe Ok for thick hardwoods, although I would say more like 500+ would have been better. So if you are sawing a large piece of old hardwood, especially ripping, with a blade that has too few (EDIT: SORRY too _many_) teeth and is not chewing away happily, I would be lowering the speed to reduce heat and possibly even speed the cut, stopping the motor from bogging down.

300 is NOT for metal....maybe brass etc? Not sure. Steel is more like 30 mpm or less, to cut all sorts, Al is fine at wood cutting speeds and I have found you get less chatter....mmmm...300 is the upper for mild steel in thinner sections IMO. Say 3mm thick? The main trouble is heat in the cut, softening the blade's temper. EDIT: and you need b bimetal blades for steel.

Just OOI, to cut thin steel you can actually ramp the speed up and either accept a buggered blade, or use the _back_ of the blade to cut the steel, by simply softening it with heat and melting your way through. I have tried it, but the saw was not really set up for it. Clear wood shavings first

Originally Posted by REALOldNick

IMO the 1000 mpm (about 3200 fpm, which is the common benchmark still) is the _most_ useful...pretty much standard for wood. What is usually more important is the blade width and teeth per inch, when cutting different woods.

300..???? Maybe Ok for thick hardwoods, although I would say more like 500+ would have been better. So if you are sawing a large piece of old hardwood, especially ripping, with a blade that has too few (EDIT: SORRY too _many_) teeth and is not chewing away happily, I would be lowering the speed to reduce heat and possibly even speed the cut, stopping the motor from bogging down.

300 is NOT for metal....maybe brass etc? Not sure. Steel is more like 30 mpm or less, to cut all sorts, Al is fine at wood cutting speeds and I have found you get less chatter....mmmm...300 is the upper for mild steel in thinner sections IMO. Say 3mm thick? The main trouble is heat in the cut, softening the blade's temper. EDIT: and you need b bimetal blades for steel.

Just OOI, to cut thin steel you can actually ramp the speed up and either accept a buggered blade, or use the _back_ of the blade to cut the steel, by simply softening it with heat and melting your way through. I have tried it, but the saw was not really set up for it. Clear wood shavings first

Thanks, nick, as you can see I am very much the novice on band saws. AS a matter of fact, the bloke that sold it to me said I am using 1000mpm, and for my purpose to stay on that speed.

Your explanations add greatly to my learning, and I appreciate that.

BB

Nurries.

I really reckon you need to start learning about and looking at blades. I do not know what came with the saw, or what your aims are, but the right blade can make a huge difference. Also sharp blades. the right blade will cut better and last longer.

I reckon the single biggest thing I can say right now is "wander"...blade wander. The sharpest blade and the best set up saw can still wander, if the blade is set a bit more one side than the other, or not as sharp one side. This can be out of the shop, or because something happened while you were sawing....DAMHIKT! It takes very little to cause enormous grief. It's probably the single most frustrating thing about a BS. You set your fence up perfectly, the blade is all nice and snug, and then you try a cut and the wood will either dive into the fence, pushing the blade out (bad) or keep wandering away from the fence (still but not as bad). As soon as this happens, ......stop the saw ......and then retrieve the work piece! As long as you are sure the saw is right, you need to calibrate the blade. IIRC (The Book is elsewhere ATM), draw a straight line parallel to a good edge, then without a fence, carefully cut along that line. When you are happy that you are following the line accurately for a few inches, again stop the saw and remove the piece, or even leave it exactly where it is. Measure the angle between the fence reference and the reference edge of the board or the line you drew, and that is what to set the fence for for that blade. Nice straight pieces of bunnings 2*1 pine become useful: over a short distance even they can have a straight edge! Or if you have a hand plane or router you can create one with care.

Here, Mark Duginske talks of actually not using a fence at all! You use a round pin or point that is set up so that you draw your cut line and use the _pin_ to maintain the distance, just slightly rotating the work piece horizontally to follow the line. It works! With practice it is actually very easy.

Of course for freehand work this is not important.

I have had more fun with a BS than any other shop tool I have ever owned. It is fluid and you interact with it. So it may take a little more concentration, but I just found it pleasant to use and immensely versatile.It is a heck of a lot safer then a TS or planer, but I used to find myself mesmerised by the line I was cutting, so do not just keep pushing until you push into the blades! I found that push sticks were very awkward on freehand curves etc. However you won't shatter you finger as you do in a TS, or remove it in a million tiny pieces as in planer. So at least it may be stitched back on!

The Bandsaw Handbook is probably worth shelling out for. IMO the guy is a bit rabid about the BS and does stuff that should be done by other tools, but it does show that if you have to have one tool, and are prepares to be a bit inventive and patient, just for the heck of it, the BS is probably that tool. It's not a bad read, but mainly for me it the go-to if I got stuck and did not want to wait for a forum reply (actually there _were_ no forums back then

I have built chairs, tables, rock band bass cabinets, boat hatches....crikey I am getting a bit emotional just remembering

Just got mine new one out of the crate and set up today!: sans table, but running, aligned and nearly ready. I actually have this conversation to thank for kicking my bum into gear and making me do it! So thanks. Earl would call it karma I guess!

BTW. Part of that thing with the delving is that I cannot drive a car without working out how every bit works...it comes in useful sometimes and is better than "ignorance is bliss"...but sometimes maybe I should just use the car to get me from A to B.....I dunno.
However it ,makes my life interesting!

Then we get to the Chinese CURSE "may you live in interesting times"........

Thank you for your attention Nick, you are obviously one who uses tools adn knows the tools you use.

I have not had this second hand BS for very long, and I am also in the situation of having the previous owner just a couple of doors from where I live. He too, is somwhat like you are in knowledge and willingness to share that knowledge.

Something I invented: It is good to have friends, it is more gooda to have good friends.

I am fortunate in that position with Tom the engineer, and Ray the woodie and now you join the ranks of those that I will listen too for my own benefit.

I have come across the wander thing, Ray who sold me the BS has given me over $130 of blades. Together we recently purchased a 20mm and a 5/16" blade. One for each of us, mine cost $15,00 ea. at 2440mm
Ray trimmed the smaller blade by lightly de-burring the back of the blade so that it could corner to its maximum ability without catching.

I have got into the habit of changing blades, even for one cut, rather than cut with an inappropriate blade that may damage in incorrect usage.

Again Thank you, I will read your information again later.

BB

OK. All good.

Well....just spent the last 2:30 hours or so setting up and tuning the new BS. Not bad. I am not sure if there is a "reviews" section, but I will post my 1st impressions.

So I am worn out from lifting, bending, shifting, bending, thinking and concentrating, have achieved exactly bugger all except pieces of wood that are smaller than they were before and increasingly straight and square, and I feel as happy as I have felt for a long time. For all my talk, I had really almost forgotten how much I love using the BS.

I remember now. Every now and then I used to get a cheap piece of pine and slice 2mm pieces off the end, just because I could

Originally Posted by REALOldNick

Well....just spent the last 2:30 hours or so setting up and tuning the new BS. Not bad. I am not sure if there is a "reviews" section, but I will post my 1st impressions.

So I am worn out from lifting, bending, shifting, bending, thinking and concentrating, have achieved exactly bugger all except pieces of wood that are smaller than they were before and increasingly straight and square, and I feel as happy as I have felt for a long time. For all my talk, I had really almost forgotten how much I love using the BS.

I remember now. Every now and then I used to get a cheap piece of pine and slice 2mm pieces off the end, just because I could

I know you are tired Nick but I think this post is a dedicated Band saw post, so your review might suit this place.

Thinking about how much the 'little woman' controls the amount of sawdust you may inhale, a mate of mine told me that his missus has a perfect way of getting attention for herself, it goes like this: When the lady wants attention she says to him "You do a couple of things for me and then we can go and have a look around "Toy World" at Bunnings"

I am slowly falling for my BS even to the point of cutting up dog bones.

Yeah I might as well post to this forum section. Just putting my thoughts in order.

HAH! I am lucky that way. I dither more than SWMBO about toys. In fact I dither so much I think I get allowed to buy things just to shut me up!

Yep. Dog bones for sure. My girl loves a nice split marrow bone off a cow. They take some cutting, but the BS is the way to go. Only trouble is cleanup after....I do tend to try to buy them split from the butcher, to avoid that.