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  1. #1
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    Thumbs up Bandsaw blade speed.

    Hi Guys,

    My wife bought me a "Titan" vertical band saw for Christmas ! I know that it is intended for wood and runs far too fast for metal. However I seem unable to find out what speed I need to use for mild steel. There seems to be lots of conflicting information, different blade types for different metals. Using SFPM for slitting saw blades suggests around 150 to 200 SFPM.

    Advice appreciated. Thanks.
    Best Regards:
    Baron J.

  2. #2
    BobL is offline Member: Blue and white apron brigade
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    I looked into this about 10 years ago and several times again since.

    Specifically for Bandsaw blades there is quite a difference depending on the band material and TPI, and the thickness and type material being cut, but otherwise I found very little conflicting info.

    Here is a chart for bimetal blades
    https://www.sawblade.com/band-saw-bl...feed-chart.cfm

  3. #3
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    Thumbs up

    Hi Bob,

    Thanks for that information, I've made a copy for future reference.

    I've taken the opportunity to take some pictures of the saw.

    28-01-2018-001.jpg
    This is the plastic cover for the top half. I uses a single screw to hold it closed. There is a peg inside that closes a switch to prevent starting if the cover is opened. The bottom door is identical but without the decal.

    28-01-2018-002.jpg 28-01-2018-004.jpg
    Both wheels are the same 9.375" inch diameter fitted with neoprene tyre.

    28-01-2018-003.jpg 28-01-2018-007.jpg
    I removed the bottom wheel so that I could measure the driving pulley diameter, which is 25.5 mm over the teeth. It is held onto the motor shaft by a left hand threaded screw. I didn't attempt to remove the pulley since it seemed very secure. There is no sign of a key, so I suspect that it is on a spline or just simply clamped against the shaft. The pulley has to come off to remove the motor, which oddly has no means of adjusting belt tension. If you look there are two nuts welded to the frame, there are no slots on the motor frame, just two bolts straight into those nuts.

    28-01-2018-005.jpg 28-01-2018-006.jpg 28-01-2018-008.jpg
    The driven wheel has a plastic toothed pulley fastened to it by three screws. This pulley is 44.5mm in diameter and is made from a plastic moulding. All the bearings in this machine are Chinese CHL 5000Z types. There are two in each wheel.

    The thought occurs to me that I should be able to fit a larger diameter pulley to this wheel and use a longer belt to slow the saw band down to a more suitable speed.

    The original saw band is 4TPI and 1/4" wide. I have bought a new saw band which is 3/8 (10mm ) wide and has 14 teeth to the inch, advertised as M42 for metal.

    So this is where I'm at for the moment.

    Thanks for looking.
    Best Regards:
    Baron J.

  4. #4
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    With a toothed belt, belt tension is not quite as critical so they can get away with not having a tensioning device.

    Michael

  5. #5
    BobL is offline Member: Blue and white apron brigade
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    From memory you'll need about 10:1 reduction in speed for MS and 20:1 for SS.
    This is quite difficult to achieve inside a BS cabinet using a single pulley replacement which is why a 3rd (speed reduction) pulley is often used.

    BJ, you might find the series of links in this post useful.
    Upright Bandsaw for cutting metal

    Another issue is band tension. MW saws use a higher tension and with most WW BS using rubber tyres on their wheels the sort of tension needed for metal sometimes ends up damaging the tyres. The tyres can of course be removed but the saw may not have enough adjustment to accomodate this.

  6. #6
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    I've seen 3 different ways of getting a wood bandsaw to the right speed.

    1. Use your lathe, put a pulley on the back end of the headstock with a belt to the bandsaw drive, use the lathe speeds and the pulley size to get the bandsaw running at the right speed.

    2. As somebody stated above, use a two or three intermediate pulleys. If you go for two pulleys they will need to be fairly big to get the right speed reductions. If you use 3 pulleys to reduce the speed they can be a lot smaller. I have seen people make pulleys out of plywood. Good writeup here https://makezine.com/2014/01/30/band...anger-reducer/

    3 Have you got access to an old drill press that you don't use any more because you now do all your drilling on a milling machine ? - One of the ones with 3 nested pulleys to give the various speed reductions - if you have then you can take the drive off the old drill press and use it to get the right speed on your bandsaw with only minor mucking about.

    4. Ive seen discussions about using a gearbox of some sort or a worm and wormwheel submerged in an oil bath but havent found anyone screaming out that they have had spectacular success using these methods

  7. #7
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    I have been thinking about varying the speed of my Band saw recently as well. Its Benchtop Ryobi HBS-100 so not sure if its worth it. Motor is only 150W.It may be time to upgrade and get a larger 14" 2 speed model at the same time.I see Rikon use 2 different sized pulleys behind the bottom wheel. Seems like a nice neat solution. Maybe hard to replicate.Also considering a 3 phase motor and VSD OR a DC motor and speed controller. ( want to maximise torque so will have to do some reading as to which is best.My Bandsaw is direct drive, so a pulley mod is more involved.Steve

  8. #8
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    Thumbs up Slowing down bandsaw to cut metal.

    Hi Guys,

    Having issues with trying to confirm what the machine handbook says and what I'm measuring. Both the handbook and printed on the motor label, says speed 11.6 Mt sec, the motor rpm is not mentioned. Now the wheels on this bandsaw are 9.375" inches diameter over the tyres, having measured the speed of the wheel with an optical tachometer at 250 rpm,

    I get Pi X 9.375" = 29.5" X 250 rpm = 7366" inches per minute, or 614' feet per minute, X 12 X 25.4 = millimetres / 1000 = 187.1 SMM. (surface metres minute) which is nowhere near 11.6 Mt sec. I cannot reconcile these two speeds. Either way it seems that I need to get down to about 60 or 65 SMM to cut mild steel, a reduction factor of nearly three.

    Somehow it seems wrong
    Best Regards:
    Baron J.

  9. #9
    BobL is offline Member: Blue and white apron brigade
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    614 fpm is very slow for cutting wood.

    11.6 m/s = 2300 fpm which seems a bit closer to the mark
    ( FWIW Most BS use 3000 fpm and even that is a long way from the optimum for cutting wood of 5000 fpm)

    It could just be a slow saw.

  10. #10
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    Hi Bob,

    I've measured the wheel rpm several times and always get a figure around 250 rpm. It fluctuates a bit 10 rpm up or down. I had expected to measure much more than that. It makes me wonder if that is why the supplied blade was 4 TPI.

    I'm looking at borrowing a mechanical tacho to confirm the rpm.

    More later.
    Best Regards:
    Baron J.

  11. #11
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    John, if you put a mark on the blade, the tacho will measure the rpm of that and as you know the circumference of it, working out the linear speed should be a doddle.

    Michael

  12. #12
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    Something not yet mentioned is the availability of Sub -1/2" steel cutting bandsaw blades. Its all good down to 1/2" but below that the suppliers of the different brands just don't list anything in their catalogues.

    Perhaps someone will have a source?

    On a different note, about Steamingbill's comment on the worm drive.The brass worm wheel can be destroyed by the wrong oil. There's a sulphur free oil that should be used as the worm wheel can end up like a piece of swiss cheese from sulphur bearing oil. It was a tip I found on the yahoo bandsaw 6 x4 bandsaw group page.

    Grahame

  13. #13
    BobL is offline Member: Blue and white apron brigade
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    Sticking the photos into Photoshop and using the Wheel diameter of 9.375", I calculate the motor pulley diameter to be around 0.9" and wheel pulley to be 1.9" in diameter which is about 2:1. If so, the motor is running only at 500 rpm which is unusual.

    If the motor is doing 1440 rpm then the wheel should be doing 720 rpm or 170 m/min which is much closer to the 187 m/min spec referred to above.

    Optical tachos are notorious for measuring too fast but I have never heard of them measuring too slow.
    If you add two pieces of reflective tape to the wheel the displayed RPM should double, if not you know you have an added reflection registering as an extra rev.

  14. #14
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    Hi Guys, Grahame, Bob, Michael,

    Grahame: There is a guy not too far away from me that makes up band saw blades, he can supply from 6 mm, 10mm and 13 mm right up to 150 mm bands. I told him that I wanted a band with a width of 10 mm and 14 teeth to the inch, 62" inches long. Which he supplied me with. However whilst the blade supplied fits and runs just fine, it needs a lot more tension than the 6 mm wide blade that the machine came with. I discovered that the blade thickness is twice that of the original, so he is going to get some blade material that is thinner and make me another one.

    Bob: The motor pulley diameter is 25.5 mm over the top of the teeth and the driven pulley is 44.5 mm in diameter over the top of the teeth. As near as I can ascertain the motor seems to run at about 1380 rpm, but the reading jumps about all over the place. Thank you for the prompt about reflective tape. I'll try that tomorrow and see if things improve.

    Michael: I should have thought of that and didn't. You are quite right that would give me the speed directly.

    I'll be back with some more info !

    Thanks Guys, your help is much appreciated.
    Best Regards:
    Baron J.

  15. #15
    BobL is offline Member: Blue and white apron brigade
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    Quote Originally Posted by BaronJ View Post
    The motor pulley diameter is 25.5 mm over the top of the teeth and the driven pulley is 44.5 mm in diameter over the top of the teeth. As near as I can ascertain the motor seems to run at about 1380 rpm, but the reading jumps about all over the place. Thank you for the prompt about reflective tape. I'll try that tomorrow and see if things improve.
    This works out to 729 rpm (my estimate was 720) so there is a factor 3 discrepancy from your tachometer reading.

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