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By Satinseat
#1335407
My old, mid 90's draper bd250 bandsaw works fine BUT the blade won't stay on the top wheel any more. Seems the front edge of the rim has been worn down so the blade runs forward (doesn't help that the tyre is convex, not flat) and off the wheel.
Tried draper but politely told the model is no longer supported. Asked for alternative fix ideas but was ignored.
Hope someone here has some positive ideas to fix this old lady.
Thanks ian :?:
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By Lazurus
#1335408
Does adjusting the tracking help, is coplanar. I am sure you could put new rubber in the wheel just need ti find a sutable profile of rubber strip perhaps:?
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By MikeG.
#1335416
Satinseat wrote:........(doesn't help that the tyre is convex, not flat) .......


It does help, actually. This is a design feature. Crown on belt wheels is important for keeping the band on, counter-intuitively.

You'll have an adjustment wheel/ knob on the outside of the cabinet at the back, behind the upper wheel. Fiddle with this a bit and see if it helps. It should actually cure this problem.
Last edited by MikeG. on 10 Feb 2020, 13:34, edited 1 time in total.
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By marcros
#1335430
fiddle with the wheel/knob very slowly. A small adjustment can make a huge difference on some models and throw the blade off the other side.

I dont know the model, but start with a an eighth or a quarter of a turn rather than a couple of turns.
By Satinseat
#1335438
Thanks, always assumed the back knob was a locking function for the top tension knob.
I'll give it another look.
By sunnybob
#1335442
25 years old and youve never had to adjust the tracking? :shock: :shock:

usually, (on MOST bandsaws), the blade teeth will be just in front of the crown of the wheel for the best results.
The rear knob tilts the top wheel fore or back to achieve this. DO NOT try to adjust the bottom wheel, that way leads to disaster!!!!
make sure you have slackened off all the guides first, or the blade will run back between then and squash all the teeth flat, killing the blade.
By heimlaga
#1335467
At the front edge and center of the rubber tyre wears more than the back edge you may some day need to recrown the tyres when the tracking adjuster cannot make the blade track anymore. That is done using a wooden sanding block and sandpaper. You use a temporary drive belt instead of the blade to decrease the risk of running the saw with the doors open.
By worn thumbs
#1335481
I might be making some wrong assumptions here.If you thought the second knob was for locking the tension mechanism,have you ever actually changed the blade?
If its an elderly blade,it might just have developed a crack or two and this sometimes encourages the blade to move.Before doing anything significant you should disconnect the machine from the electricity supply.At which point you can slowly rotate the wheels by hand while you look for a crack or cracks.If you find any its game over for the blade and you bin it.

If the blade appears undamaged or you need to fit a new one,you will have to track it anyway.As has been mentioned you need the thrust wheels and guides out of the way while you get the blade centred.With tension on the blade you slowly rotate the wheels and adjust the tracking knob until the blade is running at the centre of the top wheel.Once correct you re-position the thrust wheels and guides and close the machine.Then re-connect the electricity supply and press the green button.All should be well and you can try a cut in a piece of scrap-don't forget to keep the top guard down low just in case the weld is imperfect and lets go early on.
By Satinseat
#1335523
Thanks for all the help. Makes a lot of sense.
I'll try these suggestions, hopefully they will help.
I've changed the blade lots of times. Always fully tightening the back nut, thinking it was to secure the wheel. But now makes sense why it would wobble without tightening.
At least son had a good laugh when I told him about tracking. He's a field service engineer for a food machinery manufacturer and knows all about tra ck (homer) ing.
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By Alexam
#1337094
Lots of things to learn when starting with a bandsaw. I hope this will be of some help to you :-
BANDSAW TUNING - UNPLUGED
BEFORE TUNING - ensure that the bandsaw is set up on a level plane and bolted, or clamped down to prevent movement. If this is a modern or used machine, ensure that it is cleaned completely and that all moving parts are free and not blocked or stiffened by a build up of sawdust etc.
Check that the condition of both upper and lower wheel tyres and that both are in good order. Should a tyre need replacement, then replace the pair and not just one tyre.
CO-PLANER - this is a term meaning that with the blade attached at normal tension and with no contact by the guides or thrust bearing on the blade, both wheels are in line with a straight edge when stationary or turned by hand. If wheels are not in line, adjustments can be made by inserting a washer or shim behind the lower wheel if required to bring it into line.
In reality, wheels are more likely not to be in co-planer, as manufacturers often set up their machinery to run efficiently and allow for a slight offset to allow for various width blades. Co-planer is not an essential point as correct tuning will show and if your bandsaw wheels are not in line, you should not treat this as so desperately important.
When tuning your machine, a major factor is the top wheel adjustment that will allow the tilting of the top wheel so that the blade can position/seat itself in the correct place on the tyre.
TIRE - BLADE POSITION. One of the most important factors of tuning is getting this right. The adjustment for tilting the top wheel will move the blade towards the front or the back of the tyre. If guides and trust bearings are near the blade during initial tuning, you can damage the blade teeth.
Turning the wheels by hand helps, but once the motor has started, the blade position can change, so be aware not to close in the guides and bearings until after the blade seating has been carried out.
BLADES - Blade tension varies with different width blades. Adjust the tension until the blade can be moved to the side by gently pressing your finger on it whilst stationary. Movement should be about 1/16" - 1/8".
Some bandsaws will have a guide or gauge for tension settings of different width blades, but these are only an approximate 'guide' and cannot be relied upon for complete accuracy.
GUIDES & THRUST BEARINGS - Often upper and lower guides and thrust bearings are fitted, although there are other devices for maintaining the blade position, whilst allowing the blade to move more freely than with guides and thrust bearings.
However, you should check the condition of the guides and thrust bearings above and below the table. They should all be clean and able to move as required if touched by the blade when running or if turned the wheels by hand.
Some guided have blocks of various composition, or bearing guides either side of the blade and depending on condition, may need replacing. Consider the composition of the blocks, or bearings, as other types may be available and may improve the overall tuning of the bandsaw.
Guides should be set just short of touching the blade when it is moving. Manually turning the wheels whenever an adjustment is made is an essential part of tuning your bandsaw.
Similarly with the upper and lower thrust bearing, at the back of the blade, these should be set so that they do not rotate when the blade moves, unless under pressure from cutting.
TURNING ON - CONNECTING POWER - After making the above adjustments, switch on very briefly and switch off again, Check to see that the blade is not hitting the guides when running, before operating the machine at full stretch.
AFTER INITIAL BLADE TUNING - Once the above has been checked, it is time to check that the cut of timber is square. Test this by making a light, shallow cut on a block of wood, then turning the wood over 180 degrees and check that the blade fits the first cut accurately. If it does not, then the table is not square to the blade and needs adjustment. Use an engineer's square to check alignment of the blade in vertical n horizontal planes.
SAW TABLE - Ensure that this is clean and can be moved easily when required. Make sure that the blade does not make contact with any part of the table or insert when running. If a fence is fitted, ensure that it moves freely and is secure when in use and check this with the engineers square.
CHANGING CUT HEIGHT AND BLADES - Each time the height level for cutting thin or thicker stock takes place, or the blade is changed, the guides and bearings will need to be checked.
If a wide or narrow blade has been set up correctly and then a change in blade size will require the guide and bearing settings to be changed. Start the tuning process again if changing blades.
By Satinseat
#1337109
Appreciate this. Took to bits, like utube video. Set up like this as best as I could. Seems blade now stays on wheels but wants to keep cutting to the left and not straight. Keep on trying!!!