Bandsaw cutting skew - HELP

[garage nut]

Found a small metal band saw at a pawn shop.

Old, but does not look like it has worked too hard.
Paid R800 for it ($70, £50 , €55)

Seems I might have found why it is so cheap. it is cutting skew in the saw axis plane.

I have watched all You Tube videos in the topic and have cleaned, deburred the slots and replaced the worn washers with thick new ones, but still...about 1.2 mm on a 50mm cut.

Any suggestions?

[dbeierl]

Get your machinist's square out. Is the blade square to the table? Does the frame swing square to the table? Is the blade tensioned enough? Too much weight on the cut? Have you tried a new blade? If the set is worn unevenly the blade can walk sideways amazingly.

[metric_taper]

A photo of the vise and bandsaw blade would be handy. So I'm guessing that the vise is not perpendicular to the blade. It should be adjustable, if not, make it adjustable. Also check the blade guides, they may not be holding the blade perpendicular to the cutting surface.

[garage nut]

1) Arm seems to be swinging square to the table. I will replace the blade with a piece of wire to take out the effect of the set of the teeth.
2) Not sure how tight the blade should be. For now it is fairly tight. How do you measure?
3) No additional weight on the blade, just the weight of the arm assembly. I have turner the spring tensioner right down.
4) I do not have any other blades apart from the one I got with the machine.
5) I took the blade guides apart and cleaned everything before re-assembling as per a YouTube suggestion.
6) Will take photo of the vice tonight.

Thanks so long

[dbeierl]

1) Arm seems to be swinging square to the table. I will replace the blade with a piece of wire to take out the effect of the set of the teeth.

Make sure also that the blade itself is square to the table. Remember that the guide rollers have to twist it, so roller clearance will have an effect.

2) Not sure how tight the blade should be. For now it is fairly tight. How do you measure?

Long ago I read 25000 psi blade tension. For a blade that's .025x0.5 inch, that would mean 625 lb/285 kg tension.

3) No additional weight on the blade, just the weight of the arm assembly. I have turner the spring tensioner right down.

Replacing the spring setup by a small hydraulic cylinder and needle valve is a good thing. With the spring, it tends to bounce at the weld, and then pretty soon it knocks a tooth off which makes the bounce worse which knocks another tooth off etc.

4) I do not have any other blades apart from the one I got with the machine.

You'll be needing some, or some blade stock and a brazing jig. And of course if it's the blade that's cutting sideways it won't stop until you change it.

[garage nut]

It seems my first task is, to get a new blade.

Currently I have a 14T blade, Is this generally the most universal blade to buy?
I will be cutting predominantly Mild Steel with the odd piece of SS or Aluminum.

The roller guides are adjusted properly. When I got the machine the previous owner did not clean them and there was evidence of wood, plastic and steel. I cleaned then and adjusted them to the blade and the whole carrier as per suggestion on You Tube. I still need to replace the rollers behind the blade as they show evidence of where the blade's back is touching them.

[natie123]

Hi Garage Nut. Have you sorted out the problem with your band saw cutting skew? I had the same problem with a saw purchased from am importer of Asian tools. I replaced the original blade with a bi-metal band saw, which made a big difference. Next time I need to replace the blade I will get a saw-sharpening shop to make up a decent blade. I also found, especially with pipe or square tubing, the saw cuts more accurately if you support it by hand to reduce the pressure on the blade (the tension cannot be adjusted on the cheapies). I want to figure out a modification to make the pressure on the blade adjustable. I will PM you with supplier details.

[metric_taper]

Garage Nut: Sorry I missed your post a few months ago. I have this same bandsaw machine.
For blade tooth density, it depends much on the thickness of the material you are cutting. If thin sheet, you want a very fine pitch blade. That goes for thin wall tubing square or round. The idea is you want at least 2 teeth in contact at any time. If the blade pitch is too course, you end up stripping teeth from the blade, as this overloads the tooth. And the harder the teeth, the more likely it is to destroy them. If the machine ever starts to hop while cutting, this ruins a blade in seconds.
Carbon steel blades are lowest cost, and general purpose for mild steel and aluminum. Stainless may require a better blade depending on hardness of the SS.