Thread: Horizontal Bandsaws

I agree with Grahame and is the way I have always done it. You can do the same with RHS as well, use v blocks to support it and cut diagonally.

The few bands bandsaw blade sites I've looked at suggest to maximise blade life, swarf clearance and hence cut speed, eliminate or minimise as many long flat section contacts as possible and size teeth to the thinnest profile part of the cut.

All this means.
- angle should be presented as a pyramid profile
- SHS as a diamond.
- I beam should be cut as an H rather than than an I, as the H only has one flat section of contact and I has two.
- flatbar should be vertical.

The other methods work OK, they just take a bit longer

Perhaps the blade manufacturers are more concerned with blade life, whereas the saw manufacturer is more concerned with safety, so recommends the most secure way of holding the stock. There must be some reason why they recommend exactly the opposite to each other. I can see how the pyramid mounting of the angle would place the angle under spring tension, possibly resulting in it letting go if enough cutting force is applied.

So I just cut some angle using both methods. The pyramid method certainly results in a less aggressive cut. That method will do me.

Originally Posted by jack620

Perhaps the blade manufacturers are more concerned with blade life, whereas the saw manufacturer is more concerned with safety, so recommends the most secure way of holding the stock. There must be some reason why they recommend exactly the opposite to each other. I can see how the pyramid mounting of the angle would place the angle under spring tension, possibly resulting in it letting go if enough cutting force is applied.

Do you mean enough force to break the angle along the spine? I doubt that the vices on this small saws can do that.

I reckon the pyramid mount might be safer than the other, which can more easily rotate the workpiece if the vice is not secured.

It would not surprise me if the Chinese saw manufacturers took the mounting charts from elsewhere and misinterpreted the recommendations.

Originally Posted by BobL

Do you mean enough force to break the angle along the spine?

No, I meant the angle might pop out of the vice. Having just tried it, I don't think that is a risk.

Originally Posted by BobL

It would not surprise me if the Chinese saw manufacturers took the mounting charts from elsewhere and misinterpreted the recommendations.

Me either.

I've found that cutting thin flat bar >4 mm, vibrates the metal as there's not enough support either side of the cut. Also when younger, been told to cut flat bar horizontally because of this. Have seen coldsaw blades break where people cut thin material on the vertical.
Makes you wonder the logic behind some of the advise in to what to believe, as some recommendations contradict one another?
Kryn

Originally Posted by KBs PensNmore

Makes you wonder the logic behind some of the advise in to what to believe, as some recommendations contradict one another? Kryn

In the end run ,one has to tryout what works the best.

I can tell you for a fact that angle section- toe up heel down can make the blade, jump, catch, come off the drive pulleys, jam in the guides and make the blade FUBAR.

My suspicion is that the thin upright leg moves/vibratates under the push of the blade.

Pyramid style, never a problem!
Flat bar takes less time to cut in the vertical than the horizontal.

For thin flat section, hold it in a sandwich of two thicker plates to stop vibration. Remember the three teeth in the cut rule.

Grahame

Originally Posted by KBs PensNmore

I've found that cutting thin flat bar >4 mm, vibrates the metal as there's not enough support either side of the cut. Also when younger, been told to cut flat bar horizontally because of this. Have seen coldsaw blades break where people cut thin material on the vertical.
Makes you wonder the logic behind some of the advise in to what to believe, as some recommendations contradict one another?
Kryn

A long time ago when I first got my saw I ripped teeth off a good bimetal blade cutting thin flat bar vertical. I have never cut it vertical again.
With thin RHS etc I stand and support the saw from going down to fast, this is where a hydraulic cylinder is needed the most.

Originally Posted by Dave J

A long time ago when I first got my saw I ripped teeth off a good bimetal blade cutting thin flat bar vertical.

See the three tooth rule.

As a high school student and later as an apprentice I was instructed about the 3 tooth rule relative to manual hacksaws.
It is of no surprise that it applies to bandsaw blades as well.

“To calculate total tooth engagement, add the width of both side walls. It should follow a minimum of 3 and a maximum of 24.
To determine the number of teeth in a cut with variable pitch saw blades and a bar stock, use the average of the pitch and multiply it by the bar stock size.”

https://bandsawblog.com/the-three-tooth-rule-2/



“ Manufacturers recommend that at least three teeth and no more than 25 always be in contact with the workpiece. Within that range, shock levels are tolerable, the pressure on each tooth is enough to ensure penetration of the workpiece, and there are enough gullets to carry away the chips produced by sawing.”

https://www.thefabricator.com/articl...chine-settings

It seems perfectly reasonable but harder to implement for we home DIY ers ie -works well in production but not so at home circumstances due to widely varied one off cuts.

Grahame

Yes that's why it ripped teeth off cutting 3mm flat bar standing vertical. So the diagrams above only apply to thicker material, or a super fine blade.

Sorry Grahame, accidentally clicked the wrong button, was supposed to be "Thanks for the Picture" Dam fat fingers
Kryn

I added extension jaws to the vice today. Just some 10x65 MS flat bar. Seems this is quite a common mod. The jack screw is just an M10 bolt. I can now cut small pieces of stock.

The aluminium plate on the moveable jaw is to keep the jaw in the correct location, as it has a very long slot which I found useless. The copper shims keeps the jaw from tilting back when tightened. I'll come up with something permanent later. Maybe some set screws in the back edge of the jaw.

I found I only needed a back jaw extension because the front jaw can slide right over in its slot and a front jaw extension just robs jaw width capacity
A longer jack screw is also really worth having

Like this.



As a recent PM email suggested, for mild steel there is also the possibility of tacking a short or complex shaped work pieces onto a longer bit of stock and holding that in the jaws.

I'm still mulling over the longer jack screw Bob. I figure I can just slip a piece of stock in between the jaws and use the 50mm bolt to take up the difference. Would save a lot of winding.

Another method I've seen for holding small pieces is to bolt a small milling vice to a piece of plate. The plate gets held in the saw vice and the workpiece in the milling vice. I have a little Myford vice I might press into action.

Do you find your saw's vice jaw kicks back and out of parallel when tightened?