J

jdmunzell

Well Known Member
Just wondering if there any secret techniques used in cutting aircraft aluminum with a bandsaw. I use a metal fine toothed blade on mine, which helps move things along, but I still get some drift off of my line that is very hard to correct. What do you guys do to prevent/minimize drifting off of the cut line?
 
Make sure the upper and lower guides are adjusted properly, this is key. Use the longest (front to back) blade your machine will take, and lower the upper guide as low as you can. Also, keep the blade at its maximum tention. Last, a new, sharp blade will cut straighter. Other than that, its just hand & eye coordination with a bit of luck :)
 
G-force said:
Make sure the upper and lower guides are adjusted properly, this is key. Use the longest (front to back) blade your machine will take, and lower the upper guide as low as you can. Also, keep the blade at its maximum tention. Last, a new, sharp blade will cut straighter. Other than that, its just hand & eye coordination with a bit of luck :)
Click to expand...

And don't cut right up to the line. Use a file or a 3M wheel, as appropriate, to finish the job.
 
It's called lead angle, Jeff...

....and it means that you cannot use a fence like you do on a tablesaw. The blades are punched and there's a slight burr on one side.

Take a piece of thin, rectangular wood like paneling and draw a straight line from one edge to the other, parallel to the edge. Then start cutting along the line until you get half way through and shut off the bandsaw while holding the piece of wood still until the blade stops. Now draw a pencil line on the table along the edge of your piece of wood. You'll now be able to see the "lead angle" of your blade...usually a few degrees off from the fore/aft grooves on the table. That is the angle that you need to make a straight cut....years of woodworking taught this.:)

Regards,
 
Band saw technique

Pierre is right, bandsaw drift is a fact of life. Takes a little practice. I worked as a cabinetmaker for years, as well as an auto mechanic, and machinist. One tip I will give you is to always "stone" the BACK SIDE of a new bandsaw blade to remove the stamping burr. Run up and tension the blade, then gently lay a stone to the rear of the running blade in an effort to round off the back of the blade equally on both sides. It just takes a little, and the results will surprise you. Also, better blades are out there, such as the Timberwolf brand, which are ground as opposed to stamped. They are more expensive for sure, but last longer. Also, a blade lubricant will really help, Boe lube stick is great, and you probably have some. You may want to try a coarser blade on your saw once you have some practice. They cut more aggressively, but last a bit longer. They don't load up with chips as fast, and run much cooler. Noisy as heck though...
Hope this helps,
Chris
 
Thanks guys for the tips. I wondered also if scoring the surface on the path you want the blade to follow would help the blade stay in the "track". What do you think?
 
I found that "metal cutting blades" are no good for aluminum. What you need is a wood cutting blade. Cuts fast and does not load up.

The quality of the blade counts, too.

Vern
 
I was using a wood cutting blade for most everything, but switched to a metal cutting blade for cutting some fairly thick stock, as I am making the flap attach brackets.
 
Vern is right. Wood cutting blades seem to work better on aluminum. The teeth are too close together on metal cutting blades and tend to load up with aluminum.
Lubricating the blade also helps the aluminum not to stick. I have an old stick of "door ease" that I coat each side of the blade with. "Pam" cooking spray works as well.
 
Also, take your time. If you try to cut to fast it will wonder around on you.

I use Boelube on my blades and have not replaced but one. (my fault for trying to cut a hinge pen)
 
Heck, I thought I was screwing up because I couldn't get the metal blades to work right! I've had the same experience - the wood blades seem to do better. I did ruin one by feeding the material in too aggressively and the blade "caught" in the work, putting a wrinkle in the blade and pretty much trashing it, it would wobble terribly after that and I replaced it.
 
It is a blade speed issue...

True metal cutting bandsaws operate between 80-200 fpm. Most of us use a wood bandsaw which operates at 400, 800, or even more fpm. Way to fast for cutting most metals. We get away with it with aluminum being a soft metal but that is where the problem of wandering comes in.
If you are using a wood band saw, follow the advice given earlier. Go slow, cut away from the line and clean up with a file, belt, or disk sander later.
 
As always when cutting soft metals like aluminum, whether drill or sawing, use high speed and minimum pressure.
 
Mel is right on (No surprise there).

What I did, and this may work for you is to cut wide of your mark and then use a bench top belt sander to remove the teeth marks and work my way down to the line. Then I would take it to the deburring wheel mounted in my drill press.

Lowes sells a 4" belt/5" disk sander for around $100. That worked great for smoothing parts. Typically I would use an 120 grit belt and a 60 grit disk.
 
When setting up the saw never let the guides run against the teeth. Drift is caused by one side of the blade being sharper than the other. If you ding into one side of the blade or other or even apply more force to one side of the blade or other you're material will begin drifting away from the side having been dulled. Drift can also be caused by the set of the teeth not being equal possibly being caused by poor manufacture, blades can drift right out of the box. Any blade given enough time is going to start drifting as it becomes worn out as it's almost impossible to wear a blade out evenly. When I cut Aluminum I use a couple drops of cutting oil made for working Aluminum. Cutting Oil seems to make the blade last a lot longer.
 
Hacksaw

I've found that a hacksaw is quicker and easier to use than a bandsaw. Haven't found anything yet in my RV-9 kit for which a bandsaw is better. If I had a do-over I wouldn't buy one.

A good complement to the hacksaw is a small bench-top cutoff saw - Harbor Freight sells an inexpensive 6-inch model that works well for quickly cutting angle.

...Joe
 
Cordless

No, my hacksaw is cordless! :D

Oh, you mean the bandsaw! Yep, plugged it in, turned it on, watched the cut drift off the line with no way to correct it. Nibbled away the excess with a few more passes and used the scotchbrite wheel to grind down the excess. For the next cut I clamped the angle in the vise, cut right down the line with the hacksaw and smoothed the edge on the scotchbrite in half the time.

Now I'll admit that I've had to relearn this a few times - about every two or three months I convince myself that the bandsaw (motorized, loud, ten times the cost) must be superior to a common hacksaw. So I plug it in, turn it on, watch the cut drift off the line......

...Joe
 
A good bandsaw blade should NOT drift.

If your bandsaw always drifts the same direction, you need a new blade. Bandsaw blades have a "set" in the teeth. If the "set" gets knocked off one side it will always "drift" to one side.
 
I've only had good thing to say about my band saw. I'm using a cheap ($130) Home Depot model (Ryobi). The speed is WAYYY to fast but it does not drift. I've tried 3 blades so far and the bi-metal combinasion blade (wood & metal) gives me the best of both world.
 
dull blades

A dull blade will drift. Circular, coping, jig, band, hand or hacksaw. They all will drift if allowed to get dull. A sharp blade is safer and easier to use.
 
I use a cheap ($100) Ryobi bandsaw to cut aluminum for my plane. I use wood cutting blades (6 teeth per inch).

Initially I also had drift. The solution I found was to use a wider blade. The bandsaw came with a 1/8th inch wide blade that drifted all over. When I switched to a 3/8th inch wide blade the drift went away.

Also, to lube the bandsaw you can use a simple candle and it works well.
 
Add a speed reducer pulley to a cheap 14" made-in-China floor model bandsaw. You want to get down around 300 FPM. Run a Lenox Diemaster II, 1/2"x.025, 14-18 varitooth. What you'll have is a setup that cuts all the common airplane stuff for not much money, and blades last a long time.

Mild steel and 4130N, low feed pressure, let the teeth do their thing.

2024T3 and 4 sheet, any way you want.

Billet 6061 and the soft alloys 1100, 3003, 5052, use stick Boelube to reduce heat and eliminate chip welding (tooth clog). Sometimes I swap blades to a lower tooth count for multiple cuts in billet greater than 1", only to save overall time.

fiberglass laminate, any way you want.

Birch ply and MDO hammerforms, no problem.

To track a straight line, apply light pressure perpendicular to the blade axis. Swing the entry angle only for a contour cut or gross correction. The Diemaster tooth set is designed for contour cutting and steers easily.
 
....and here I thought it was just me. Nice to see I have plenty of company in this area, and that the problem is universal.

Back to one of my questions, has anyone tried scoring along or near the line to be cut to see if that would help keep the blade from drifting?
 
Charlie Brown

Awww, Jon, why did you have to go and post that tip to use a 3/8-inch wide blade? Now I'm gonna have to try one. I feel like Charlie Brown about to kick the football again.

...Joe
 
Cut close to the line and then belt sand up to the line. Straight edge everytime. That's why they had Burr King belt sanders all over United. By the way I love my burr king sander! :D Cutting right on the line invites trashing a part.
 
Good Blades Make the difference!

Good Blades Make the difference! Bad ones lose kerf and sharpness quickly:(


I ordered a bunch of Lenox blades from bandsawbladesdirect.com, wood and metal cutting. They are made to your specs and very reasonably priced.

My wood blade cuts through heavy aluminum effortlessly:)

I used to go through the craftsman ones every couple months, The last lenox "wood blade" (craftsmen discontinued my oldy but goody model) is still in my saw and working like new.

They do have a min order but its worth it, you will have a supply of great blades that will last you a long time.
 
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