Band saw cut are not straight

[handyman2020]

I am using my hands to move 2.5inch steel 304 tube into to fixed Vertical saw (something like below), which are not giving perfect straight cuts as the tube moves a bit and then its not straight cut anymore, even a simple circle cut with steel tube are something 2 degrees off.

I am looking for some very low budget options to help getting straight cuts, any type of DIY jig etc, or anything else which can help with this, I can make a simple JIG if there are few ideas to help with this issue.

its becoming very annoying and frustrating because when cuts are not straight, I have to do heaps of grinding and then it opens another can of worms



Regards

 

[rlitman]

I don't think there's a great answer to this. Bandsaw and scrollsaw blades themselves tend to not cut straight when at a perfectly square thrust angle, and the necessary angle for a straight cut will vary with tooth wear.

 

[slowtwitch73]

Easy stuff.... blade, tension, feed. Bad blades will not cut straight, blades are usually too loose, try more speed and less feed.

Not so easy stuff.. machine is not straight and needs tuning.

 

[Notgrownup]

Go through the cut slower, don’t force the cut and as above, blade tension needs to be good and tight.

 

[OccupantRJ]

Use a pipe cutter to score a line around the tube to follow while slowly rotating the tube, or use tape to create a line around it to follow, or use a wraparound to mark a line around the tube. If the tube is long enough to hang off the table, use a clamp on it to prevent unwanted rotation By holding onto the clamp. A tube in a freehand band saw seldom cuts square. I rotate all tubing while cutting if possible, and it is easier on the saw teeth. I keep an 18 wavy tooth blade on my vertical bandsaw because I cut a lot of thinner materials on it. My saw shop guy is amazed at how long the flexback blades I use will last me when I get one made up. Being the only person using a saw makes a big difference in blade life.

 

[RoninB4]

-Buy good quality blades and set the tension as posted above. Also check the alignment of the blade guides themselves with a straightedge. This is especially true for less expensive machinery from Chi-Wan where the build quality is always suspect. Blade speed is also important, cutting 300 series SS needs to be much slower than cutting regular steel. Speed for cutting SS is similar to cutting tool steel, look it up.

I've used large industrial grade vertical bandsaws for decades and getting a straight cut was often a problem. It could have been from some idiot co-worker running the blade too fast and dulling the teeth or simply waiting for someone else to put a new blade in. One idiot cut concrete garden borders and ruined a $200 blade while laughing about it.

I adopted a habit of expecting the blade to cut at an angle. I'd use a magic marker to darken the background and scribe lines for the cut so I could instantly detect the cut going astray. This is part of what machining is, the operator adapts to the machine condition. Yes it's a bit of extra work making and following the scribed lines but it ensures greater accuracy and allows you to move on to the next process with minimal trouble.

 

[OccupantRJ]

deleted

 

[alfadan]

I made a simple 90⁰ fence for the slot of my 14in vertical. Find a way to securely hold the part; cutting round stuff without a vise or something, especially tubing, can be dangerous as the blade can grab and twist it out of your hand.

 

[Rusted Nut]

Is it not cutting correctly vertical or horizontal? Blade tension, correct blade, correct speed, guides set properly, saw level, material level, align blade and stock clamp.

 

[jack stand]

The blade roller guides are the heart of a true cut. That's not discounting everything above ie; blade speed and tension, tooth count correct for the material thickness, etc.
It might take a hour or a day, but "dialing in" your saw will make it a pleasure to use and can become a real challenge that's worth the time.
Determining that the blade is square to the base or in your case, the T square and slots.

 

[kctgb]

Take your belt off and rap it around the tubing to be cut, use a wide belt if you have one. trace a line on the edge of belt and cut on line around the tubing. It's not a perfect way to get a straight line, it's a low cost way.

 

[kctgb]

If you have some time and welding skills, you could make this. I whipped this up for a welding job in the field, I had to cut a bunch of square tubing. Surprisingly it cuts very straight and it’s fully adjustable. I needed it for one job so I used scraps laying around to make it. It’s nothing more than a shoe a portable bandsaw slips into and held in place with small machine screws. I’ve had it and used it for years, my biggest expense was buying the harbor freight portable band saw. The base is made from 3/4 plywood and some scrap angle. I use C clamps to hold the material to be cut. It’s simple and basic and works. Use good blades

 

[rlitman]

If you have some time and welding skills, you could make this. I whipped this up for a welding job in the field, I had to cut a bunch of square tubing. Surprisingly it cuts very straight and it’s fully adjustable. I needed it for one job so I used scraps laying around to make it. It’s nothing more than a shoe a portable bandsaw slips into and held in place with small machine screws. I’ve had it and used it for years, my biggest expense was buying the harbor freight portable band saw. The base is made from 3/4 plywood and some scrap angle. I use C clamps to hold the material to be cut. It’s simple and basic and works. Use good blades

I really like what you did there, but I think it would work even better if you turned that wood block around, so the blade pulled your clamped parts towards the fence, rather than away from it.

 

[kctgb]

Yes you are correct. If I did it that way I would have to rearrange the switch and electrical cord. It was meant to be a one time use down and dirty tool to get the job done. I slapped it together in two hours for the job the next day. With the fence the way it is I could cut 45 cuts I needed for the job.

 

[handyman2020]

If you have some time and welding skills, you could make this. I whipped this up for a welding job in the field, I had to cut a bunch of square tubing. Surprisingly it cuts very straight and it’s fully adjustable. I needed it for one job so I used scraps laying around to make it. It’s nothing more than a shoe a portable bandsaw slips into and held in place with small machine screws. I’ve had it and used it for years, my biggest expense was buying the harbor freight portable band saw. The base is made from 3/4 plywood and some scrap angle. I use C clamps to hold the material to be cut. It’s simple and basic and works. Use good blades

I bought the band saw red one in photo below, but it couldnt cut 90 degree supertight mandrel elbow bends so ....




so.... I bought the harborfreight convertor stand to make the bandsaw vertical as the red one above wont go vertical/high enough and I needed vertical saw to cut tubes

Universal Portable Band Saw Benchtop Stand

Amazing deals on this Universal Portable Band Saw Stand at Harbor Freight. Quality tools & low prices.

www.harborfreight.com

I removed the bottom part and made it permanently vertical, perhaps I should put it back?


Provided that I have both types of stands, stock one, which came with red saw and the harbor freight convertor/stand

what are my options to get straight cuts, even on 90 degree elbow tube

 

[kctgb]

I bought the band saw red one in photo below, but it couldnt cut 90 degree supertight mandrel elbow bends so ....




so.... I bought the harborfreight convertor stand to make the bandsaw vertical as the red one above wont go vertical/high enough and I needed vertical saw to cut tubes

Universal Portable Band Saw Benchtop Stand

Amazing deals on this Universal Portable Band Saw Stand at Harbor Freight. Quality tools & low prices.

www.harborfreight.com

I removed the bottom part and made it permanently vertical, perhaps I should put it back?


Provided that I have both types of stands, stock one, which came with red saw and the harbor freight convertor/stand

what are my options to get straight cuts, even on 90 degree elbow tube

It sounds like your problem is the saw won’t open far enough to cut the tubbing? Keep in mind the bigger the tubbing the more chance the cuts won’t be straight. On the saw I made it will open all the way. When I’m off work I’ll show you what I did to make it open and how to stop the saw from going all the way over. You may have to buy a quality horizontal band saw to cut big tubbing.

 

[handyman2020]

It sounds like your problem is the saw won’t open far enough to cut the tubbing? Keep in mind the bigger the tubbing the more chance the cuts won’t be straight. On the saw I made it will open all the way. When I’m off work I’ll show you what I did to make it open and how to stop the saw from going all the way over. You may have to buy a quality horizontal band saw to cut big tubbing.

I am not going above 3 inches of tubing for now, you think that saw is okay for upto 3 inches diamater?

 

[kctgb]

I am not going above 3 inches of tubing for now, you think that saw is okay for upto 3 inches diamater?

That’s pretty big for that small saw. Go to the HF website and see if it gives any specific measurements for cutting depth.

 

[ez-duzit]

A small, cheap bandsaw will not produce the results you need. You'll need to dress the out-of-square ends on a disc sander.

 

[kctgb]

This is how high the saw I made will lift with a stop in the back to prevent it from going all the way over. It will cut 4 inch square tubing damn near perfectly square. It’s down and dirty simple.

 

[ArcIndWeld]

I bought the band saw red one in photo below, but it couldnt cut 90 degree supertight mandrel elbow bends so ....




so.... I bought the harborfreight convertor stand to make the bandsaw vertical as the red one above wont go vertical/high enough and I needed vertical saw to cut tubes

Universal Portable Band Saw Benchtop Stand

Amazing deals on this Universal Portable Band Saw Stand at Harbor Freight. Quality tools & low prices.

www.harborfreight.com

I removed the bottom part and made it permanently vertical, perhaps I should put it back?


Provided that I have both types of stands, stock one, which came with red saw and the harbor freight convertor/stand

what are my options to get straight cuts, even on 90 degree elbow tube

The only way ive found to get good tubing cuts on a portband is a saw guide like ones from Techsouth. Ive done tons of sanitary tubing that way. That being said for cutting elbows I would get one of those holding jigs and use that as a cut guide in a horizontal saw. TICON makes a fancy $$ one or you can get some 3dprinted ones relatively cheap on ebay/etsy and such

 

[PCustoms]

Good belt or large disc sander tuned up will give perfect flat faces, and can be used to clean up square of angled cuts.

 

[handyman2020]

Good belt or large disc sander tuned up will give perfect flat faces, and can be used to clean up square of angled cuts.

I have this but it takes forever with 30 grit on 2.5inch steel tube 304 when the cuts from bandsaw above are not great.

I will look a used disc sander online on craigslist etc.

 

[handyman2020]

DEWALT Portable Band Saw Blade, 44-7/8-Inch, .020-Inch, 24 TPI, 3-Pack (DW3984)

this is the blade I have on that portable band saw,

​

should I get other type of blade to see better results?

 

[ez-duzit]

I have this...

That is only a toy. Not up to the job.

 

[Wiz02]

I don't know if this trick (not hack - hate that corruption of the meaning of hack) will work for a band saw, but a hose clamp provides a straight cutting guide for a hack saw when cutting tubing.

 

[PCustoms]

I have this but it takes forever with 30 grit on 2.5inch steel tube 304 when the cuts from bandsaw above are not great.

I will look a used disc sander online on craigslist etc.

That is only a toy. Not up to the job.

I have a Craftsman unit, I think half horsepower. I've put a lot of one by one and 2x2 tubing through it it's barely up to the task, but when I've got it set up correctly you can really make a nice square joint

 

[ez-duzit]

This is what you want at a minimum: Rockwell/Delta 12" disc/6" x 48" belt. IIRC I paid $350 for it, used.

 

[cannuck]

I am using my hands to move 2.5inch steel 304 tube into to fixed Vertical saw (something like below), which are not giving perfect straight cuts as the tube moves a bit and then its not straight cut anymore, even a simple circle cut with steel tube are something 2 degrees off.

I am looking for some very low budget options to help getting straight cuts, any type of DIY jig etc, or anything else which can help with this, I can make a simple JIG if there are few ideas to help with this issue.

its becoming very annoying and frustrating because when cuts are not straight, I have to do heaps of grinding and then it opens another can of worms



Regards

If that is the saw you are using, why are you in verticle mode instead of clamping in vise for a horizontal cut????

If you need dead square, as already mentioned use the correct tool (i.e. pipe/tube rolling cutter) and deburr the ID. If you want to use the saw, you need to start with the finest pitch, highest quality blade you can get. Stainless can be a proper PITA to cut, so you need LOW speed and flood of correct coolant. The next problem is blade width. Narrow blades do not track straight very well, but you are pretty much stuck with what you've got. Next issue is saw setup (as again has been mentioned). Before attempting any cut, you need to look carefully at your guide roller bearings (or square blade guides in older/larger saws). Take ALL of the clearance out of blade guides. Use a pieced of square tubing and do a test cut, First, get your vice square to the blade (if it is adjustable). Then do a horizontal cut in the vice and flip it 180 over and cut a slim slice from the opposite side. "Steer" with blade "twist" adjustment until the little offcut slices are exactly same dimension (i.e. dead square). Even with a 3/4" or 1" saw blade, this takes a bit of time and care and even then you will be lucky to keep it within a couple degrees. I should have mentioned: extend your blade guide to close the gap so tube just fits between guides. Getting dead square cuts from a bandsaw is not easy. Trying to do it freehand is almost impossible.

When I need dead square on short blanks of round stuff I will offcut with bandsaw and leave 0.050" or so to square up in lathe. To do in vertical mode, you need a sliding, adjustable feed guide (there is probably a slot in your table to do this. If you just want as close to square as practically possible, use pipe cutter instead. There we are, right back where I started.

 

[PCustoms]

This is what you want at a minimum: Rockwell/Delta 12" disc/6" x 48" belt. IIRC I paid $350 for it, used.

That's a nice sander to shoot for, but getting hard to find especially at that price!

I have the same in as this (pic stolen from NUTTSGT thread)

 

[ez-duzit]

...Stainless can be a proper PITA to cut, so you need LOW speed and flood of correct coolant...

Flood coolant is practical on a production machine but, for this one cut, all you need is stick lube. However he will never produce excellent results with that cheap bandsaw. For any real accuracy you want a heavy duty machine similar to this one on the left.

 

[PCustoms]

Flood coolant is practical on a production machine but, for this one cut, all you need is stick lube. However he will never produce excellent results with that cheap bandsaw. For any real accuracy you want a heavy duty machine similar to this one on the left.

OP can't possibly make his exhaust unless he buys a CNC tube laser obviously.

BTW irish spring makes an acceptable stick lube that can be bought on a Sunday in almost any store

 

[M.Brane]

My little old Central Machinery saw makes straight cuts no problem as long as the blade is good. Only took a few cuts with a fresh blade to dial it in. A bit of Tap Magic makes nice chips, and helps the blades last.

 

[kctgb]

My little old Central Machinery saw makes straight cuts no problem as long as the blade is good. Only took a few cuts with a fresh blade to dial it in. A bit of Tap Magic makes nice chips, and helps the blades last.

Those little bandsaws are pretty good for home use. It takes a little time to adjust everything but they cut straight. Make sure it’s on a perfectly level floor.

 

[jack stand]

DEWALT Portable Band Saw Blade, 44-7/8-Inch, .020-Inch, 24 TPI, 3-Pack (DW3984)​

​

this is the blade I have on that portable band saw,​

​

​

should I get other type of blade to see better results?

Band Saw Blade Teeth Per Inch (TPI) Chart

TPI is arguably the most important decision when selecting a band saw blade. Use Dakin-Flathers bandsaw teeth per inch chart for optimum performance.

www.dakin-flathers.com

Is your saw purpose built for metal cutting?
A wood cutting saw turns much faster than a metal saw.

 

[cannuck]

Here is a DoAll wheel for those who might wonder what a range of blade speeds and materials are needed for every cutting job.

Steve Summers on Instagram: "Got a speed chart for the DoAll saw! 🥳 A awesome viewer of my YouTube channel Joe Maloney had a old saw he wasn't going to repair and donated its chart to the cause. Old machines can be organ donors too ya know! This cha

761 likes, 41 comments - stevesummers80 on July 23, 2021: "Got a speed chart for the DoAll saw! 🥳 A awesome viewer of my YouTube channel Joe Maloney had a old saw he wasn't going to repair and donated its chart to the cause. Old machines can be organ donors too ya know! This chart is perfect...

www.instagram.com

 

[handyman2020]

Band Saw Blade Teeth Per Inch (TPI) Chart

TPI is arguably the most important decision when selecting a band saw blade. Use Dakin-Flathers bandsaw teeth per inch chart for optimum performance.

www.dakin-flathers.com

Is your saw purpose built for metal cutting?
A wood cutting saw turns much faster than a metal saw.

Band Saw Blade Teeth Per Inch (TPI) Chart

TPI is arguably the most important decision when selecting a band saw blade. Use Dakin-Flathers bandsaw teeth per inch chart for optimum performance.

www.dakin-flathers.com

Is your saw purpose built for metal cutting?
A wood cutting saw turns much faster than a metal saw.

yes, its bi metal

 

[handyman2020]

This is what you want at a minimum: Rockwell/Delta 12" disc/6" x 48" belt. IIRC I paid $350 for it, used.

Its a dream to get that for $350 where I am located. I would have already if I could


what you do think about evolution chop saw, seems to be making amazing cut, have a look at video

 

[ez-duzit]

Buy a real bandsaw.

 

[cannuck]

what you do think about evolution chop saw, seems to be making amazing cut, have a look at video

If you are cutting relatively small stuff (angle, flat, small channel) the Evo is a good bet. If you need to cut big stuff (S and W beams, big square and rectangular tubing) a horizontal band is really needed (I have a 7 x 10 that is most useful, but old saw with swivelling vice - DO NOT recommend that - get one with swivelling cutting head). If you need to cut really big stuff (such a trimming pieces off of a assembled part) you need a portaband or monster vertical (I have a pair of Marvel 8s to do that when I get big shop up). For hand feeding, though, you need a dedicated vertical (I just scored a 12 x 16 DoAll to replace the little vertical I have used for years. So: as you can see, no one saw does it all, but IMHO the basic saw for a home shop should be a mid sized, swivelling head exactly as shown in ezduzit's post #31.