Gallery, Projects and General => Neat Stuff => Topic started by: NeoTech on August 01, 2013, 01:01:39 AM

Title: Bandsaw - diy.
Post by: NeoTech on August 01, 2013, 01:01:39 AM
So i stumbled across this on another forum. Its a 24" inch bandsaw and by looking at it i figured this one isnt that too hard to construct if you got a welder and pile of scrap tubing and some spare time. I let images speak for themselves.

Finished product

Frame assembly

Tracking casters

Band tensioner

Blade guide

Seems that the casters is 6" poly urethan casters and the blade is riding on the crown. Upper right is blade tension lower left is motor drive..
Upper left and lower right is blade tracking. Im guessing he is running a bi-metal blade in this able to cut frame tubing.
He saids e he built it 25 years ago intially and still uses it to the day..

Shoutout goes to GAB or G.Barnes over at the forum for this.

Think this is gonna be my vacation project with some alu casting mixed in there. ;)
Title: Re: Bandsaw - diy.
Post by: PekkaNF on August 01, 2013, 03:50:42 AM
Good thing that people make these....however I don't like the looks of this particular design:

1) Wheels are very small (probably to make it compact and cheap), but small wheels are not a good idea with band saw. You need a lot of band tension and there is minimum recommended radius for each band saw blade thickness. I have googled couple sometimes, but forgot. I think it would be a good idea to google first some values about band saw tension/wheel diameter/durability before making too many welds. I saw once one workking band saw, that was workked hard, because the guy turns parts (Ex. lathe operator). The wheels on that one were made out trailer wheel rims (turned unnecessary parts off) and trailer wheel hubs with taper bearing.

2) The body of that saw looks weak.

Title: Re: Bandsaw - diy.
Post by: awemawson on August 01, 2013, 04:13:01 AM
My immediate reaction is that the wheel diameters are far too small, and the blade will crack from fatigue, but I may be totally wrong - it has been known  :wave:
Title: Re: Bandsaw - diy.
Post by: NeoTech on August 01, 2013, 04:25:10 AM
yeah i dont know actaully.. i have seen commercial versions with smaller wheels about 6-7" in diameter. Metal bandsaws are way slower as well. And the diameter of the wheels takes surface speed down as well..

GAB claims this saw of his has been working fo 25 years.

But i agree can be a good point to check blade tension and minimum radius.. But take into consideration the bend is less in this design than with the ones with two wheels due to the four contact points. Unless you make those two wheels really big.. I dont really have space for the height of such a machine though.. When i researched smaller bandsaws the table top models they usually have one larger wheel in the bottom then a smaller idler and only one top skateboard wheel sized upper idler. But they are made for smaller diameter bandsaw blades as well..

Need to do some more research.
Title: Re: Bandsaw - diy.
Post by: PekkaNF on August 01, 2013, 05:08:13 AM
I did consider at one point building one myself, did some research and decided to buy one small 4*6", because it will do most what I need.

I did consider 3-wheel design like this:

That design has been used commercially several times and offers pretty deep throat for it's size.

The turning radius will be always smaller on smaller wheels. Wrap angle will be less, but I think it is of smaller consequence here.

I don't mean to discourage you, on the contary.

Are you making the band saw to cut only thick pieces of metal or some other materials as well?

Title: Re: Bandsaw - diy.
Post by: NeoTech on August 01, 2013, 06:47:58 AM
Im mainly looking to making a bandsaw to cut steel and aluminium and maybe plastics.. But its mainly for being able to countouring knife blanks before grinding and milling. =)
Title: Re: Bandsaw - diy.
Post by: S. Heslop on August 01, 2013, 07:02:12 AM
If he's using thin blades, the wheel diameter shouldn't be a problem. It's a quite vertically compact design.

One of the things i'm planning to build in the near future is a Matthias Wandel ( style bandsaw, but without easy access to a planer thicknesser i'm considering making the frame from welded box section, although that might become quite pricey so i'm still thinking about it.
Title: Re: Bandsaw - diy.
Post by: S. Heslop on August 01, 2013, 07:27:38 AM
How thick is the material you're going to be cutting? A thicker (and wider!) blade allows for more tension and beam strength to try prevent it from deflecting when cutting through very thick materials, 12 inch slabs of hardwood kind of thick, but if you're only planning to rough cut thin stock there's no reason why a thin wheel and blade would be a problem, but it'd give the saw less versatility.
Title: Re: Bandsaw - diy.
Post by: NeoTech on August 01, 2013, 10:58:55 AM
thickets blade stock i use is 6mm A1, and the more common is 4mm D2 and some O1  (AISI standards).. So its not that thick.. And then of course i could cut tubing, pipe and sheets on that thing.. I dont expect to cut 200mm thicj slabs of steel on it anyway.. =)
Title: Re: Bandsaw - diy.
Post by: vtsteam on August 01, 2013, 11:08:49 AM
I have 3 band saws, one of which I built. They are the usual 4x6 metal cutting Chinese mfg type, A 24" home built bandsaw mill for lumber making, and a 3 wheel Duplicarver 24" throat bandsaw that I have owned for 32 years. I once owned a 28" cast iron vertical bandsaw made by American Sawmill Machinery Company, which I used in my boatshop

Definitely blade life is reduced on multi wheel band saws used for cutting wood. Why is wood worse? Because the blade speed is higher by a big factor. Why are multi wheel saws worse -- two reasons. They have smaller wheels, AND they are seen as bigger saws. Bigger saws are used on heavier stock. Heavier stock implies thicker and wider blades. Thicker and wider blades fatigue faster. Metal fatigue is what kills the blades much more quickly than any other cause in a multi wheel band saw.

Would I trade my multi-wheel 24" saw for another two wheel band saw? No. Why? Because I can move it into a boat and do joinery there, rather than hopping into and out of a hull to make my cuts with a more massive two wheel wide throat saw. It is compact. That is its only advantage.

Shortly after I bought my saw, the manufacturer spent a lot of money to send out, at cost, a speed reducer for the saw, because the rate of blade breakage was so severe that customers were returning them left and right. I believe that Duplicarver may be out of business now -- possibly long since gone. Not sure.

Speed reduction helps, but it's not a particularly good way to solve the problem. Kind of a band-aidapproach.I also buy relatively thin and narrow (3/8") blades for it (actually, I have a roll of blade stock, and silver solder bands now.)

The wheels are 8-1/4" diameter. Ideally, for wood cutting, bandsaw wheels should be 12 for good blade life and a good range of blade widths. Six inches seems like a very small diameter, to me. I suppose a 4 wheel might be better than a 3 if the angle of the turn is less (90 deg vs 120 deg), but I don't know the answer to that. Radius and the number of flexes would seem to me the real determinant to metal fatigue. As soon as a crack starts, you're done.

A multi wheel saw shows its greatest advantage if it is portable, I think. So a 4 wheel, to me looks bulkier and heavier than a 3 wheel. Seems to me, different ready made wheels could have been chosen with a little more diameter, and a 3 wheeler produced. They don't have to be solid wheels, by the way. My big sawmill uses pneumatic trailer tires and wheels.

Anyway just my experience here, yours may and will vary -- and our purposes and usage are/were probably different. Hope it helps.

EDIT: just saw further down the thread where you say the main usage is cutting steel and aluminum and making knife blanks -- so wood cutting isn't much of a concern. I would say that wheel diameter is far less of a concern with a slow turning metal cutting blade compared to wood cutting. Although I do wonder why such a large saw was wanted then.  Maybe you also want to mill wood for handle blanks from timber?
Title: Re: Bandsaw - diy.
Post by: NeoTech on August 01, 2013, 11:27:29 AM
It seems like i should cast the wheels for this thing myself. Would be easier to get larger sized wheels that way.. Or just weld them up from rolled steel.

But yeah a 24" throated version is what will work best for me, i can make it so it fit my ceiling height (180cm) and it can be easily rolled to the side standing on casters..
Title: Re: Bandsaw - diy.
Post by: AR1911 on August 30, 2013, 10:29:00 PM
My vertical bandsaw is one of the ubiquitous 14" wood saws.  Actually, mine is a 1990 Jet variant Wood/Metal, though the minimum speed was only suitable for aluminum. By substituting a 60 RPM gearmotor for the original 1725 RPM motor, and eliminating the step pulleys, I got to 110 FPM for less than $150. Works great.  That same saw is sold at HF and most other import tool dealers.