Bandsaw Blade Guide theory!

[Ttrees]

A true co-planar adjustment now

And accurate wheel alignment thereafter, don't pinch the shaft when doing adjustments,
I've wrote a bit more on that elsewhere, basically a north or a south needs loosening,
in order to adjust the east or west jacking screws.

Motor pulley depth checked, new belts can have a lump at the join to throw you off.
Need better lighting, (the camera doesn't like that)

Turned out there's no such thing as flat tires, this Centauro tire from the dealer,
was infact crowned, and the apex was 17.5mm from the front edge.

There's 1mm between the centre of the tire, and the actual crown,
which could make the difference if running extremely narrow blades,
regarding wiping out the crown, and things going wonky.

Just cuz they might appear flat at first glance, when in a circumference,
this is certainly not what the blade feels.

a thicker block as to align it with the wheels on two axis

Just a mock up shot, showing some saw plate, but what's missing here is the suitable blade installed in order to keep the
upper wheel from tipping, and the beam for making the it co-planar.
Not doing so, can wipe out the apex of the crown very quickly,
and to make note once the apex is dressed enough to be concentric, then
one can remove enough material from the tool, as not to take off any more than needed.

 

[Ttrees]

The lower wheel ain't as tricky since it's rigid, thus not needing a blade installed,
and made easier by advancing the scraper
in a pivoting fashion, using the folded lip of the chassis.
Advancement of the cutter done easily with little taps, of some sort of wedge,
turned out the old mortise holes in the scrap used for the block, was very handy.

Use some tape for yer paintjob, and ply for the floor of the machine,
if using lesser clamps, or have nice paint.

Finally running very sweetly now, phew!
Took me far too long to figure all that out.
P.S, did I say best get a Centauro CO with a foot mounted motor, so it's actually possible to align everything?

Cheerio
Tom

 

[mc281]

If you take a look on Google and type in bandsaw blade guides you will find a lot of articles and threads about which is the best bandsaw blade guides, but little if any on the theory which may explain why one might be better than another. However, one thing all agree upon for the ‘normal’ blade guides, which includes all of the bandsaw blade guide manufactures I’m aware of, is that they should not touch the blade. There is an exception, and these are ceramic blade guides. For now, we will not consider these, but will return to them later.

The point about them not touching the blade is important. In theory, bandsaw blade guides are completely useless! They arnt required, they will do nothing at all. So what have them? Well, firstly, let’s consider a bandsaw which has no blade guides. The blade is fully tensioned and tracking properly for the tyre / wheel configuration of the saw. The blade is properly tracked to a fence. The blade is band new, properly sharpened and has an equal set on the teeth on either side of the blade, so that the kerf width is even either side of the blade. We are running the saw at the correct speed, we have the right tooth pitch (TPI) and tooth geometry for the material, we are cutting. Lastly we start feeding the material, at the correct speed into the blade. What will happen? The material will be cut by the blade perfectly, it will be a straight cut without any incident or issues. This applies to all material thicknesses.

It appears that you are happy to ignore HSE guidance then?

 

[deema]

@mc281 I think the phrase your referring to in the HSE guideline is ‘They should support the blade but not grip it during cutting’. Blade guides should be as close to the blade as they can be without touching it according to HSE. They are a safety device to help prevent blade twist / breakage. If blade guides touch the blade they cause friction, heat it up, reduce blade tension and create the scenario they are there to reduce the risk of.

 

[Robbo3]

If you do a lot of bowl cutting or similar it will stress/wear one side of the teeth more and you may then struggle to cut straight lines from the fence on ripping work.

Cut one clockwise & the next anticlockwise. Hopefully all the blanks won't be too big to cut the anticlockwise ones.

 

[Robbo3]

The point about them not touching the blade is important. In theory, bandsaw blade guides are completely useless! They arnt required, they will do nothing at all. So what have them? Well, firstly, let’s consider a bandsaw which has no blade guides. The blade is fully tensioned and tracking properly for the tyre / wheel configuration of the saw. The blade is properly tracked to a fence. The blade is band new, properly sharpened and has an equal set on the teeth on either side of the blade, so that the kerf width is even either side of the blade. We are running the saw at the correct speed, we have the right tooth pitch (TPI) and tooth geometry for the material, we are cutting. Lastly we start feeding the material, at the correct speed into the blade. What will happen? The material will be cut by the blade perfectly, it will be a straight cut without any incident or issues. This applies to all material thicknesses.

EthAnswers proved this in a video posted 6 years ago
-

 

[MikeJhn]

Well that certainly blows a few myths out of the water.

 

[pulleyt]

EthAnswers proved this in a video posted 6 years ago
-

I'd back up the demonstration in the video. I've been very happy with the resawing using the jig I made and the conclusion I came to is that a slow feed rate is possibly the most important factor in avoiding blade drift.

 

[Spectric]

I came to is that a slow feed rate is possibly the most important factor in avoiding blade drift.

The issue with a bandsaw is that you need a wider range of different blades to suit the material and changing a blade is not a five minute job so people try to get away with the blade fitted which causes issues, a lesson many learn like myself the hardway. You need the right number of teeth in the material to get a decent cut otherwise you get wander, like any cutting tool you need to keep the cut clear of waste so with lots of teeth and a large thickness it just clogs up. Also a sharp blade, once dull they need changing and quality blades as many blades supplied with a machine are hopeless, here Record blades fit this category well and using decent blades changed my BS400 completely.

 

[Phil Pascoe]

I've never understood the the manufacturers saving pence by putting cheap blades on expensive machices.

 

[MikeJhn]

Price point and accountants budgets.

 

[Phil Pascoe]

A few pence on a machine costing several hundred quid or more? Strange thinking to me.

 

[MikeJhn]

The issue with a bandsaw is that you need a wider range of different blades to suit the material and changing a blade is not a five minute job so people try to get away with the blade fitted which causes issues, a lesson many learn like myself the hardway. You need the right number of teeth in the material to get a decent cut otherwise you get wander, like any cutting tool you need to keep the cut clear of waste so with lots of teeth and a large thickness it just clogs up. Also a sharp blade, once dull they need changing and quality blades as many blades supplied with a machine are hopeless, here Record blades fit this category well and using decent blades changed my BS400 completely.

Most of us are inherently lazy, we come to a point in making something in the workshop and get the idea that we need to cut something on the bandsaw, but its the wrong blade, but the one fitted will do, I know I have done that, own up the rest of you.

 

[MikeJhn]

A few pence on a machine costing several hundred quid or more? Strange thinking to me.

Obviously not an accountant, but someone that has to think for a living.

 

[Phil Pascoe]

Most of us are inherently lazy, we come to a point in making something in the workshop and get the idea that we need to cut something on the bandsaw, but its the wrong blade, but the one fitted will do, I know I have done that, own up the rest of you.

Not too guilty.

 

[Terry - Somerset]

Obviously not an accountant, but someone that has to think for a living.

Even accountants (of which I was one) may recognise the attraction of being able to market a machine for which reviews consistently praised the quality of the blade included.

The clear benefits - (a) it represents a competitive advantage, (b) the brand reputation is enhanced when the buyer switches on the machine and it works properly, and (c) the additional cost is more than justified by the increased number of machines sold.

The policy of fitting poor blades may be an engineering decision based on the proposition that (a) if a couple of blades are supplied, they may not be the ones needed, and (b) an engineer would regard the blades as consumables to be replaced anyway.

 

[Richard_C]

Cut one clockwise & the next anticlockwise. Hopefully all the blanks won't be too big to cut the anticlockwise ones.

Unless you are preparing blanks to look nice for sale there is no need to make them round. Just cut a load of tangents so you have a hexagon, octagon or almost anything. No need to change to a narrow blade, faster, easier, no 'set' on the teeth.

Anyway, after 2 years with my small hobby Bandsaw, Axi 1950, I had my first big bang blade weld failure. Odd as it was an undemanding cut. "Whassthat" I thought as I hit the stop button. Column right down to the workpiece and all contained in the machine so fine, just made me jump.

Now I have a 2m long very floppy saw, must be useful for something, surely? Perhaps not, into the metal recycle. Unless....

 

[MikeJhn]

Handles on either end, a two man saw as used to be used in saw pits, just down the road near Sittinbourne there is a "Sawpit Lane"

 

[Phil Pascoe]

Unless you are preparing blanks to look nice for sale there is no need to make them round. Just cut a load of tangents so you have a hexagon, octagon or almost anything ...

Except we're often trying to use the maximum capacity of the lathe so he blank needs to be round.

 

[Robbo3]

The issue with a bandsaw is that you need a wider range of different blades to suit the material and changing a blade is not a five minute job so people try to get away with the blade fitted which causes issues, a lesson many learn like myself the hardway. You need the right number of teeth in the material to get a decent cut otherwise you get wander, like any cutting tool you need to keep the cut clear of waste so with lots of teeth and a large thickness it just clogs up. Also a sharp blade, once dull they need changing and quality blades as many blades supplied with a machine are hopeless, here Record blades fit this category well and using decent blades changed my BS400 completely.

Agreed. But it can be done if you take it slowly.
This is a 300mm cut with a 6tpi blade where I was too lazy to change the blade for just this one cut.