Bandsaw tension

[pjwillms]

Looking for advice after using the bandsaw do you nock the tension of all the time. The thing is if you forget to put the tension back on then start the machine.it could damage the blade.ty

 

[Spectric]

Looking for advice after using the bandsaw do you nock the tension of all the time. The thing is if you forget to put the tension back on then start the machine.it could damage the blade.ty

This is down to self discipline, I always take the tension of my BS400 until it is required and it has become second nature to just pull the lever down to re tension when needed as it is much better to leave the frame without the stress and the blade relaxed. This is probably more important with modern sheet metal fabricated machines than the big old beast of yesteryear which were really solid.

 

[pjwillms]

Yes I did not think of the tension on the frame ty

 

[Hypnotic Chimera]

This is down to self discipline, I always take the tension of my BS400 until it is required and it has become second nature to just pull the lever down to re tension when needed as it is much better to leave the frame without the stress and the blade relaxed. This is probably more important with modern sheet metal fabricated machines than the big old beast of yesteryear which were really solid.

I hadn't really considered this for my lately acquired cheapo.
Mine doesn't have a lever, and the tension handle is a removable plastic knob.
It's also a sheet metal frame.

Additionally, when tensioning up it does move the blade outwards on the bottom wheel (perhaps the bottom wheel needs to be adjusted on the axle angle adjustment bolts on the back of the machine?)
The tyres are also flat to my eye, with no visible curve as per the ones filmed on YouTube...

Which leaves me in a bit of a quandary.

Either I leave it tensioned and risk stretching the blade and also deforming the frame in the longer term; or I de-tension after each use and then go through a set up process before each use.

I all seems so obvious now that permanent tension is sub-optimal.

 

[Spectric]

When I was looking for a bandsaw I had the BS350 in mind and when I visited Biven Machinery to take a look I first thought how little extra space the 400 requires and a bigger table so was swayed towards it. Then chating with Dave he pointed out how much easier it is to replace the blades because the 400 has the de-tension lever. Now we know how easy it is to not change a blade even if the job requires more or less teeth and anything that can make it an easier process will mean that you are more likely to use the correct blade and get better results so this made me go for the 400 over the 350. Then in use using this tension lever you realise just how much tension is put onto the machine and being from an engineering background it just made sense not to leave it tensioned. The issue is as mentioned is that if you have to wind the tension off and back on then it is a pita especially if it effects the blade setup.

Luckily for me I can change blades and adjust tension to suit but alignment remains, both wheels are exactly in line as per snodgrass and blade runs central.

 

[pjwillms]

Thanks for that

 

[Hypnotic Chimera]

When I was looking for a bandsaw I had the BS350 in mind and when I visited Biven Machinery to take a look I first thought how little extra space the 400 requires and a bigger table so was swayed towards it. Then chating with Dave he pointed out how much easier it is to replace the blades because the 400 has the de-tension lever. Now we know how easy it is to not change a blade even if the job requires more or less teeth and anything that can make it an easier process will mean that you are more likely to use the correct blade and get better results so this made me go for the 400 over the 350. Then in use using this tension lever you realise just how much tension is put onto the machine and being from an engineering background it just made sense not to leave it tensioned. The issue is as mentioned is that if you have to wind the tension off and back on then it is a pita especially if it effects the blade setup.

Luckily for me I can change blades and adjust tension to suit but alignment remains, both wheels are exactly in line as per snodgrass and blade runs central.

Since the tyre on mine appears to be flat, not crested/curved, I've set up the blade so that the gullets track the very front edge of the tyres - such that the kerf is overhanging and doesn't chew the tyre or create unnecessary friction or even a high frequency vibration.

Being a complete novice, the tension I tried first was random but quite tight, with the blade deflection (pushing on it outwards inside the main upright) was around 3-4mm by eye before it got "very tight" on the finger. I ran the machine quickly and then opened the doors to check blade tracking. The lower wheel seemed to be slightly upwards deflected with the blade kind of in the right place at 9 and 3 o'clock (where it meets the wheel tangentially), but the kerf was overhanging off the tyre edge by maybe 2mm by eye at the bottom 6 o'clock position. This is what gave the appearance of the bottom wheel being pulled upwards out of vertical alignment (axle centre-line not horizontal, minutely deflected upwards at wheel hub).

Reducing the tension only very, very slightly (around 1/4 to 1/2 turn) remedied that lower wheel blade tracking issue but kept a decent taught-ness on the blase and it still "twangs" when plucked. So I left it there...


Just thinking out loud at this point, but maybe I need to adjust the bottom wheel centre-line. (bottom axle bearing bolt screw in, top axle bearing bolt screw out.)

 

[REB]

Looking for advice after using the bandsaw do you nock the tension of all the time. The thing is if you forget to put the tension back on then start the machine.it could damage the blade.ty

After I started my Laguna bandsaw too many times without putting the tension on the blade, I created and 3D printed this. I glued some small magnets on the back and place it on the table when tension is removed, and stick it on the upper cabinet when tension is applied.

 

[deema]

Leaving the tension on the blade decreases the life of the bearings. Bearings have a static and dynamic load characteristic, and depending on model / intended user, the mean time between failure (MTBF) for a given loading might be fairly short. @Sideways and I reverse engineered a SCM S45 bandsaw and made significant upgrades as a consequence. The thread is available on the forum.

Good practice is to remove the tension of any belts when the machine isn’t in use.

 

[pjwillms]

That's very good where did you get it from did you print it

 

[REB]

That's very good where did you get it from did you print it

As stated, I created and 3D printed it myself

 

[RobinBHM]

Looking for advice after using the bandsaw do you nock the tension of all the time. The thing is if you forget to put the tension back on then start the machine.it could damage the blade.ty

Ive never bothered with narrow bandsaw machines (IM referring to blades from 1/8" to 1")

but re-saw machines with blades from 2 1/2" to 6" need to have the tension released as all the time they are tensioned that is the same as them being in use -it alters the tension and soon they will have to be sent off for resharpening and tensioning

 

[paulm]

Never bothered taking the tension off on my Startrite machine in the last thirty years, no discernible real world issues with wheel tyres, bearings or blades, likewise my small Rexon machine.

Better for me to have the machines ready to use without the need to fiddle with settings and adjustments, especially when you just want to do a few cuts.