Bandsaw question, optimal location of the lower blade guides?

[Dennis Aspö]

The lower blade guides on my saw are rather primitive to say the least:
https://farm8.staticflickr.com/7503/15890430156_f0b9c4a65f_b.jpg

There are only side guides and no thrust bearing on the back like most saws would have, even most vintage saws. The whole guide assembly is placed rather far down too in my opinion. Looking carefully at other designs it seems they have the lower assembly further up. It makes sense to me, the less distance between the upper and lower guides, the better tracking you ought to have, right? I'm thinking of trying to make a better set of guides from wood and mount on a riser block to get it closer to the underside of the table. The videos of Matthias Wandels bandsaw build has given me lots to go on when it comes to building one and it looks like a very simple construction. Question is if it's worth it?

[Rod Sheridan]

At least they're easy to reach.

I find some of the more modern saws have them located so close to the underside of the table that you need a squirrel with a mechanical engineering degree to adjust them.

I wouldn't actually worry too much about no rear guide on the bottom, I've run a saw with no guides on occasion.................Regards, Rod.

[John TenEyck]

I think the question behind your question is "How well does the saw cut now?" If it cuts straight then why fool around with something that's not an issue? Simple is good if it works. Now if it won't cut straight, and you've run down all the usual suspects related to alignment and the blade with no resolution, then it's worth pursuing a new set of guides.

John

[Dennis Aspö]

Yeah I haven't tried resawing anything large yet, small things it cuts okay.

Though while we're at it, anyone know a cheap way to measure bandsaw speed? I am beginning to wonder if the aftermarket motor my saw came with, isn't too fast after all. Motor has no plate so I can't say how fast it is.

[Dan Cameron]

Yeah I haven't tried resawing anything large yet, small things it cuts okay.

Though while we're at it, anyone know a cheap way to measure bandsaw speed? I am beginning to wonder if the aftermarket motor my saw came with, isn't too fast after all. Motor has no plate so I can't say how fast it is.

Put some white paint on a section of blade, count number of revolutions in a minute, measure blade length, and do the math.

[Dennis Aspö]

I figured that'd move way way too fast for me to count. I'll give it a try I suppose.

[Lee Reep]

This is a "must watch" video for anyone with questions on setting up bandsaws. I had issues with drifting and getting decent resawing results until I watched this video. Alex covers bearings, blade placement, and tensioning. I also am really impressed with the Carter guide he uses for narrow blades to allow more "scrolling" type of cutting. With it, you get rid of the lower blade guides. I'd love to have a second, larger bandsaw dedicated to resawing, and use this single guide on my Powermatic 14" bandsaw. He has been doing this awhile. Beware, though, he moves so fast on his demos I was convinced he was going to cut off a finger or two ... :eek:

https://www.youtube.com/watch?v=wGbZqWac0jU

[Judson Green]

How about a revolution counter? Check out amazon.

[Dennis Aspö]

OK I painted the bandsaw blade white in a spot, then I used my DSLR camera and recorded it running and went through it frame by frame in virtualDub. Got these results:

00:06:006 blade movement starts

00:07:341 white is spotted
00:07:925 and again

.58 seconds for a lap, still spooling up to full speed however.

00:10:260
00:10:469

Now a lap takes about .2 seconds

00:19:770
00:19:937

.167 seconds

00:33:242
00:33:408

.166 seconds, this is more or less the end speed.

Now my blade length is 4445 millimeters or 4.45 meters and that means the speed of the blade is around 26,7 meters per second or 88 feet per second. This translates to about 5280 feet per minute. I've heard 25-26m/s as being a good speed for a modern bandsaw of equivalent size so perhaps I am near optimal speed anyway.

I tried the SFPM calculation which is (Motor RPM X Motor Pulley Diameter / Driven Pulley Diameter X Band Saw Wheel Diameter X 3.1416 / 12) and I put 1 for both pulley diameters as I have a direct drive saw. Going backwards with that my motor ought to be around 840rpm. Strange speed, figured it'd be either 700 or 900 RPM. But perhaps inaccuracies in my measuring method are to blame.

[Rick Moyer]

At least they're easy to reach.

I find some of the more modern saws have them located so close to the underside of the table that you need a squirrel with a mechanical engineering degree to adjust them.

I wouldn't actually worry too much about no rear guide on the bottom, I've run a saw with no guides on occasion.................Regards, Rod.
Thanks Rod, made me laugh when I needed too.

[Myk Rian]

Yeah I haven't tried resawing anything large yet, small things it cuts okay.

Though while we're at it, anyone know a cheap way to measure bandsaw speed? I am beginning to wonder if the aftermarket motor my saw came with, isn't too fast after all. Motor has no plate so I can't say how fast it is.
Harbor freight has a nice fpm/rpm meter.

[Judson Green]

Motor rpms, what might be on the name plate, are based on no load. Even though you're not cutting something there is still quite a load on the motor.

Any idea the HP of this motor?

[Dennis Aspö]

No HF in Finland, we got "Biltema", "Clas Ohlson", "K-rauta", and "Motonet". And more yet. Still I don't think I'm gonna bother with that now, the cheapest laser rpm meters where almost 40 euros. This was free and I think it was accurate enough.

[Dennis Aspö]

Motor rpms, what might be on the name plate, are based on no load. Even though you're not cutting something there is still quite a load on the motor.

Any idea the HP of this motor?

It's too bad the plate is missing, or it's positioned so it's on the underside and taking it off to check would mean removing the wheel and having to rezero the lower wheel all over. Based on the contactor to the motor it's rated for a 5kw motor at 400 volts. I am not an electrician so I am not really sure what all of it means. I mean there's some labels indicating star-delta but I don't think the motor uses that and I thought star delta was a manually controlled start anyway.