Bandsaw seems to lack power, knowledge and help would be appreciated

[Baxidur]

Hello

I'm a mechanic by trade and need some advice about bandsaw cutting - I bought a draper bs350c for spares or repairs off fleabay as the motor wasn't working - I replaced the motor with a new 4 pole cap start 750watt motor as well as replacing all the bearings and it seems to run fine, but when I try to cut some 50mm white ash along the the grain it seems to be really lacking in power - my cut speed seems to be around 1cm/minute no matter which blade tpi or 400/800 rpm speed I use - if I go any faster my blade just bogs down and stalls the motor, Is this normal for a 750watt motor vs 50mm ash?


Thanks in advance for any replies or thoughts on this matter

 

[Jacob]

Blunt blades? Too fine a blade, should be 3 or 4tpi ish? Blade tension too low (slipping)? Blade not well aligned? Guides missing?

 

[MARK.B.]

Did you replace the cap ? when you changed the motor . drive belt slipping, blade slipping/binding/tension not right.

 

[powertools]

Hi and welcome from a retired mechanic.
It does sound to me that you are using a blade that is to fine.

 

[Stuart Moffat]

Hello

I'm a mechanic by trade and need some advice about bandsaw cutting - I bought a draper bs350c for spares or repairs off fleabay as the motor wasn't working - I replaced the motor with a new 4 pole cap start 750watt motor as well as replacing all the bearings and it seems to run fine, but when I try to cut some 50mm white ash along the the grain it seems to be really lacking in power - my cut speed seems to be around 1cm/minute no matter which blade tpi or 400/800 rpm speed I use - if I go any faster my blade just bogs down and stalls the motor, Is this normal for a 750watt motor vs 50mm ash?


Thanks in advance for any replies or thoughts on this matter

It reminds me of my early days with a bandsaw a few decades ago. I managed to put the blade on "inside out" which means it is effectively running backwards. To check, with the thing turned off, run a finger gently up and down the blade. It should bite into you skin as you go upwards, and not bite going downwards. If the blade is inverted it will bite on the dowards stroke. If that has happened, take the blade off and (with gloves on) you need to invert it so that the current outside faces inwards onto the tyre.

 

[Baxidur]

Firstly thank you all for your replies - tis appreciated!

@Jacob the saw came with 15 or so blades that seemed in good condition, tried 3, 3 skip, 4, 6 and 8 tpi all with same slow cutting speed, so after doing some research i purchased a brand new axminster 4 tpi which i tried yesterday with same result, Tension seems fine as does alignment and guides - at least the blade runs true consistently.

@MARK.B. Motor came with brand new cap already attached, is it worth running a cap test on it? Also the wiring layout/colours where different so I kind of winged it when it stalling the motor, but I thought the cap was just to bumpstart the motor? The drive belt slipping idea has some traction though *groans* sorry couldn't resist that awful pun, will look into that though , should be a fairly easy check.

@powertools as I said with Jacob I have tried various blades, but my research led me to 4tpi , would you recommend a different blade size?

@Stuart Moffat the blades teeth are pointing downwards and are cutting ok, will triple check though.

Thanks again for all the replies, seems a good community here.

 

[Phil Pascoe]

This sounds like mine. Mine stalls in long grain 25mm softwood. It has the correct new blade, perfectly set guides and a new capacitor. The bearings are fine and doesn't slow when running with no load. The tension is fine and the blade runs properly on the tyres.
The saw will rip 175mm softwood when running properly.
Sorry, OP, for the hijack, but it sounds similar.

 

[Baxidur]

Just checked and the drive belt is slipping, guess it needs to be a lot tighter than I expected, but it seems bearings are also shot on the drive belt tensioner, so I'll drop a new post here when new bearings arrive and I can crank up the tension - but my gut tells me this was the problem and that new bearings and tension will sort it, either way it needed fixing - so a big thanks goes out to @MARK.B.

@Phil Pascoe I would recommend the same check I just made - increase your feed speed until your blade bogs down and stops moving then check the fans on your motor to see if its still spinning, if it is then increase drive belt tension a bit - rinse and repeat.

 

[MARK.B.]

Happy to hear you have got it sorted . Same thing was happening to me only a few weeks ago the belt had only been on the machine from new for 17 years so i can say as a Yorkshire man - I got my money's worth out of it .

 

[EddyCurrent]

The manual for that saw says the motor is 1100 Watt input.

 

[Spectric]

As Eddy says the motor should be 1100 Watts and should it be a two pole not a 4 pole, do you think the blade speed is slow but the 4 pole gives higher torque. A case of 4 pole = 1800 RPM against 2 pole at 3600 RPM.

From my experience the blade is very critical, don't want to many teeth in the material and quality makes the difference between cutting straight and just curves.

 

[Phil Pascoe]

Just checked and the drive belt is slipping, guess it needs to be a lot tighter than I expected, but it seems bearings are also shot on the drive belt tensioner, so I'll drop a new post here when new bearings arrive and I can crank up the tension - but my gut tells me this was the problem and that new bearings and tension will sort it, either way it needed fixing - so a big thanks goes out to @MARK.B.

@Phil Pascoe I would recommend the same check I just made - increase your feed speed until your blade bogs down and stops moving then check the fans on your motor to see if its still spinning, if it is then increase drive belt tension a bit - rinse and repeat.

Thanks for the suggestion - I'll check that.

Loose drive belt. The one thing it didn't occur to me to check.. Thank you.

 

[EddyCurrent]

The motor on my Startrite is a two capacitor, start and run motor. I don't know what the original Draper motor was but there is quite a difference in performance between a start only motor and a start/run motor.

 

[Baxidur]

@MARK.B. Well as a Lancashire man myself I just checked the year of manufacture - 2007 and the belt looks worn enough to be original - so expect a post in 4 years letting you know that the belt is still going strong and that I beat you

@EddyCurrent True - not sure if it has been changed out in the past or if draper was cutting corners but the motor drive wheel was 14mm ID and the smallest 1100w drive shaft I could find was 24mm, as it was with the 750watt 19mm drive shaft I had to take the drive wheel to the lathe to get it to fit and there wasn't enough meat on it to take it out to 24mm really um'd and ah'd before going with the 750watt motor but I would have had to replace the motor - drive wheel - band wheel and drive belt adding a few hundred to the project which I couldn't really justify

@Spectric Where did you find that it should be 2 Pole? the motor on it was 4 pole and I checked the turn ratios by taping the bandblade and doing a full revolution whilst checking turns on motor with the calc coming out at around 1400rpm for the motor.

@Phil Pascoe Glad to hear it - Still waiting on my bearings, has it made a big difference?

 

[Spectric]

Where did you find that it should be 2 Pole?

No I asked whether it should be a two pole,

and should it be a two pole not a 4 pole

If you had thought the blade was running slow this could be a reason. But at least you know the problem is that sliping drive belt. As someone mentioned they do need quiet a bit of tension to prevent slipping and is because the motor pulley is often a small diameter with little angle of lap.

 

[Baxidur]

@Spectric My apologies, its come on beer o'clock and I misread your post - and it makes sense about the drive belt tension vs motor pulley diameter, I was leaving some slack in the pulley as I didn't want to damage the belt, is some slippage acceptable if I over feed? or should I be aiming for tight enough that it stalls the motor if I overfeed?

 

[Phil Pascoe]

@Phil Pascoe Glad to hear it - Still waiting on my bearings, has it made a big difference?

A huge difference, I'm just peed off I didn't think to check something so elementary.

 

[MARK.B.]

One little tip is to pay close attention to the underside/inside of the belt as it ages , I vac out the inside of the cabinet often as the dust extraction is and pass a cursory glance over the belt and to be honest it has always looked OK . It was only after it had failed and was now laid out flat without tension that I noticed that the underside/inside outer layer was Badly worn/frayed/cracked and so weak i could pull pieces away with little effort . Couple of pics showing the wear and where it failed for those that like me always like to see pics . A quick check now will take little if any effort or time but could save you load's of time and effort ,if you think of the ordering/waiting on delivery (Sending it back coz ya got fat digits and wonky eyes and click the wrong one ) Waiting on another delivery and then to add insult to injury The circlip pliers that you will in all probability need to remove the lower wheel will not be where you were so bloomin sure they would be . It was around this time that my Good Lady popped her head into the workshop doorway and smiling sweetly handed me a and offered to have a look around ,barely holding it together at this point I sarcastically said " go right ahead let me know when you fed up looking " and with a loud Hurumph i sat down turning my back on her as I slurped noisily at my coffee . Only two or three minutes had passed before sickly sweet word's " Are these what you are looking for dear " were whispered in close proximity to my left lughole while over my right shoulder appeared the offending item . She never said another word just gave me " The Look " and softly closed the door on her way out. Now Gentlemen believe me when i tell you " The Look " was enough to send a shiver down my spine and i may just have peed a little . In the last 40 plus years " The Look " has been used to devastating effect and it's not because i know that it will not end well for me, for that is a forgone conclusion . It's the not knowing WHEN she will seek her " Pound of Flesh that really gets to me .
Please just take a look guy's and save yourself all of the above.

P.S. If you do not hear from me again You know who it was

 

[Spectric]

I believe it is a multi Vee / poly vee belt, the same as the FEAD belt on most automotive applications and they do not like slipping, this can quickly damage the belt. The setup looks very similar to the Record bandsaws with the ability to have one of two speeds by moving the belt onto the other pulleys.

Only cheap to replace so maybe worth having a spare Draper BS350C Bandsaw Drive Belt

It is interesting to note that for the Record BS350 you have a choice of std quality or a premium Contitech belt.

 

[Spectric]

Forgot to add that once setup with no belt slippage you should find it very hard to stall the blade if you are not over feeding and have the right blade with not to many teeth in the material. A rule of thumb I picked up was to always ensure that you have at least three teeth in the material being cut but no more than ten.